RFC: switch the remaining architectures to use generic GUP

RFC: switch the remaining architectures to use generic GUP

[Christoph Hellwig]

Hi Linus and maintainers,

below is a series to switch mips, sh and sparc64 to use the generic
GUP code so that we only have one codebase to touch for further
improvements to this code.  I don't have hardware for any of these
architectures, and generally no clue about their page table
management, so handle with care.  But it at least survives a
basic defconfig compile test..

RFC: switch the remaining architectures to use generic GUP

[Christoph Hellwig]

Hi Linus and maintainers,

below is a series to switch mips, sh and sparc64 to use the generic
GUP code so that we only have one codebase to touch for further
improvements to this code.  I don't have hardware for any of these
architectures, and generally no clue about their page table
management, so handle with care.  But it at least survives a
basic defconfig compile test..

[PATCH 1/6] MIPS: use the generic get_user_pages_fast code

[Christoph Hellwig]

The mips code is mostly equivalent to the generic one, minus various
bugfixes and one and a half arch overrides that this patch adds to
pgtable.h.

Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has
pte_special and pte_mkspecial implemented and used in the existing
gup code.  They are no-op stubs, though which makes me a little unsure
if this is really right thing to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/Kconfig               |   2 +
 arch/mips/include/asm/pgtable.h |  30 ++++
 arch/mips/mm/Makefile           |   1 -
 arch/mips/mm/gup.c              | 303 --------------------------------
 4 files changed, 32 insertions(+), 304 deletions(-)
 delete mode 100644 arch/mips/mm/gup.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 70d3200476bf..53a103cdc352 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,6 +6,7 @@ config MIPS
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_UPROBES
@@ -55,6 +56,7 @@ config MIPS
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
+	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 4ccb465ef3f2..a6fd98563837 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -20,6 +20,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 #include <asm/pgtable-bits.h>
+#include <asm/cpu-features.h>
 
 struct mm_struct;
 struct vm_area_struct;
@@ -651,4 +652,33 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
  */
 #define pgtable_cache_init()	do { } while (0)
 
+static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+{
+	unsigned long len = (unsigned long)nr_pages << PAGE_SHIFT;
+	unsigned long end = start + len;
+
+	return !cpu_has_dc_aliases && end >= start;
+}
+#define gup_fast_permitted gup_fast_permitted
+
+#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	pte_t pte;
+
+retry:
+	pte.pte_low = ptep->pte_low;
+	smp_rmb();
+	pte.pte_high = ptep->pte_high;
+	smp_rmb();
+	if (unlikely(pte.pte_low != ptep->pte_low))
+		goto retry;
+
+	return pte;
+}
+#define gup_get_pte gup_get_pte
+#endif
+
+static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
+
 #endif /* _ASM_PGTABLE_H */
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index f34d7ff5eb60..1e8d335025d7 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -7,7 +7,6 @@ obj-y				+= cache.o
 obj-y				+= context.o
 obj-y				+= extable.o
 obj-y				+= fault.o
-obj-y				+= gup.o
 obj-y				+= init.o
 obj-y				+= mmap.o
 obj-y				+= page.o
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
deleted file mode 100644
index 4c2b4483683c..000000000000
--- a/arch/mips/mm/gup.c
+++ /dev/null
@@ -1,303 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for MIPS
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- * Copyright (C) 2011 Ralf Baechle
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <linux/swap.h>
-#include <linux/hugetlb.h>
-
-#include <asm/cpu-features.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#else
-	return READ_ONCE(*ptep);
-#endif
-}
-
-static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t *ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if (!pte_present(pte) ||
-		    pte_special(pte) || (write && !pte_write(pte))) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		SetPageReferenced(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	pte_unmap(ptep - 1);
-	return 1;
-}
-
-static inline void get_head_page_multiple(struct page *page, int nr)
-{
-	VM_BUG_ON(page != compound_head(page));
-	VM_BUG_ON(page_count(page) = 0);
-	page_ref_add(page, nr);
-	SetPageReferenced(page);
-}
-
-static int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pmd;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_huge(pmd))) {
-			if (!gup_huge_pmd(pmd, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pte_range(pmd, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pud;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_huge(pud))) {
-			if (!gup_huge_pud(pud, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pmd_range(pud, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch
-	 * size will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the page and take a ref on it.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int ret, nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start || cpu_has_dc_aliases)
-		goto slow_irqon;
-
-	/* XXX: batch / limit 'nr' */
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-slow:
-	local_irq_enable();
-
-slow_irqon:
-	/* Try to get the remaining pages with get_user_pages */
-	start += nr << PAGE_SHIFT;
-	pages += nr;
-
-	ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
-				      pages, gup_flags);
-
-	/* Have to be a bit careful with return values */
-	if (nr > 0) {
-		if (ret < 0)
-			ret = nr;
-		else
-			ret += nr;
-	}
-	return ret;
-}
-- 
2.20.1

[PATCH 1/6] MIPS: use the generic get_user_pages_fast code

[Christoph Hellwig]

The mips code is mostly equivalent to the generic one, minus various
bugfixes and one and a half arch overrides that this patch adds to
pgtable.h.

Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has
pte_special and pte_mkspecial implemented and used in the existing
gup code.  They are no-op stubs, though which makes me a little unsure
if this is really right thing to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/Kconfig               |   2 +
 arch/mips/include/asm/pgtable.h |  30 ++++
 arch/mips/mm/Makefile           |   1 -
 arch/mips/mm/gup.c              | 303 --------------------------------
 4 files changed, 32 insertions(+), 304 deletions(-)
 delete mode 100644 arch/mips/mm/gup.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 70d3200476bf..53a103cdc352 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,6 +6,7 @@ config MIPS
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_UPROBES
@@ -55,6 +56,7 @@ config MIPS
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
+	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 4ccb465ef3f2..a6fd98563837 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -20,6 +20,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 #include <asm/pgtable-bits.h>
+#include <asm/cpu-features.h>
 
 struct mm_struct;
 struct vm_area_struct;
@@ -651,4 +652,33 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
  */
 #define pgtable_cache_init()	do { } while (0)
 
+static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+{
+	unsigned long len = (unsigned long)nr_pages << PAGE_SHIFT;
+	unsigned long end = start + len;
+
+	return !cpu_has_dc_aliases && end >= start;
+}
+#define gup_fast_permitted gup_fast_permitted
+
+#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	pte_t pte;
+
+retry:
+	pte.pte_low = ptep->pte_low;
+	smp_rmb();
+	pte.pte_high = ptep->pte_high;
+	smp_rmb();
+	if (unlikely(pte.pte_low != ptep->pte_low))
+		goto retry;
+
+	return pte;
+}
+#define gup_get_pte gup_get_pte
+#endif
+
+static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
+
 #endif /* _ASM_PGTABLE_H */
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index f34d7ff5eb60..1e8d335025d7 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -7,7 +7,6 @@ obj-y				+= cache.o
 obj-y				+= context.o
 obj-y				+= extable.o
 obj-y				+= fault.o
-obj-y				+= gup.o
 obj-y				+= init.o
 obj-y				+= mmap.o
 obj-y				+= page.o
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
deleted file mode 100644
index 4c2b4483683c..000000000000
--- a/arch/mips/mm/gup.c
+++ /dev/null
@@ -1,303 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for MIPS
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- * Copyright (C) 2011 Ralf Baechle
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <linux/swap.h>
-#include <linux/hugetlb.h>
-
-#include <asm/cpu-features.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#else
-	return READ_ONCE(*ptep);
-#endif
-}
-
-static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t *ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if (!pte_present(pte) ||
-		    pte_special(pte) || (write && !pte_write(pte))) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		SetPageReferenced(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	pte_unmap(ptep - 1);
-	return 1;
-}
-
-static inline void get_head_page_multiple(struct page *page, int nr)
-{
-	VM_BUG_ON(page != compound_head(page));
-	VM_BUG_ON(page_count(page) == 0);
-	page_ref_add(page, nr);
-	SetPageReferenced(page);
-}
-
-static int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pmd;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_huge(pmd))) {
-			if (!gup_huge_pmd(pmd, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pte_range(pmd, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pud;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_huge(pud))) {
-			if (!gup_huge_pud(pud, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pmd_range(pud, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch
-	 * size will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the page and take a ref on it.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int ret, nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start || cpu_has_dc_aliases)
-		goto slow_irqon;
-
-	/* XXX: batch / limit 'nr' */
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-slow:
-	local_irq_enable();
-
-slow_irqon:
-	/* Try to get the remaining pages with get_user_pages */
-	start += nr << PAGE_SHIFT;
-	pages += nr;
-
-	ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
-				      pages, gup_flags);
-
-	/* Have to be a bit careful with return values */
-	if (nr > 0) {
-		if (ret < 0)
-			ret = nr;
-		else
-			ret += nr;
-	}
-	return ret;
-}
-- 
2.20.1

[PATCH 2/6] sh: add a missing pud_page definition

[Christoph Hellwig]

sh oddly enough had pud_page_vaddr, but not pud_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/include/asm/pgtable-3level.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 7d8587eb65ff..8ff6fb6b4d19 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -37,6 +37,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 {
 	return pud_val(pud);
 }
+#define pud_page(pud)		virt_to_page((void *)pud_page_vaddr(pud))
 
 #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
-- 
2.20.1

[PATCH 2/6] sh: add a missing pud_page definition

[Christoph Hellwig]

sh oddly enough had pud_page_vaddr, but not pud_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/include/asm/pgtable-3level.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 7d8587eb65ff..8ff6fb6b4d19 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -37,6 +37,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 {
 	return pud_val(pud);
 }
+#define pud_page(pud)		virt_to_page((void *)pud_page_vaddr(pud))
 
 #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
-- 
2.20.1

[PATCH 3/6] sh: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sh code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/Kconfig               |   1 +
 arch/sh/include/asm/pgtable.h |  85 +++++++++++
 arch/sh/mm/Makefile           |   2 +-
 arch/sh/mm/gup.c              | 277 ----------------------------------
 4 files changed, 87 insertions(+), 278 deletions(-)
 delete mode 100644 arch/sh/mm/gup.c

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index b77f512bb176..2fd8c12ca128 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,6 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
+	select HAVE_GENERIC_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 3587103afe59..d3c177144f90 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -149,6 +149,91 @@ extern void paging_init(void);
 extern void page_table_range_init(unsigned long start, unsigned long end,
 				  pgd_t *pgd);
 
+static inline bool __pte_access_permitted(pte_t pte, u64 prot)
+{
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) = prot;
+}
+
+#ifdef CONFIG_X2TLB
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	/*
+	 * With get_user_pages_fast, we walk down the pagetables without
+	 * taking any locks.  For this we would like to load the pointers
+	 * atomically, but that is not possible with 64-bit PTEs.  What
+	 * we do have is the guarantee that a pte will only either go
+	 * from not present to present, or present to not present or both
+	 * -- it will not switch to a completely different present page
+	 * without a TLB flush in between; something that we are blocking
+	 * by holding interrupts off.
+	 *
+	 * Setting ptes from not present to present goes:
+	 * ptep->pte_high = h;
+	 * smp_wmb();
+	 * ptep->pte_low = l;
+	 *
+	 * And present to not present goes:
+	 * ptep->pte_low = 0;
+	 * smp_wmb();
+	 * ptep->pte_high = 0;
+	 *
+	 * We must ensure here that the load of pte_low sees l iff pte_high
+	 * sees h. We load pte_high *after* loading pte_low, which ensures we
+	 * don't see an older value of pte_high.  *Then* we recheck pte_low,
+	 * which ensures that we haven't picked up a changed pte high. We might
+	 * have got rubbish values from pte_low and pte_high, but we are
+	 * guaranteed that pte_low will not have the present bit set *unless*
+	 * it is 'l'. And get_user_pages_fast only operates on present ptes, so
+	 * we're safe.
+	 *
+	 * gup_get_pte should not be used or copied outside gup.c without being
+	 * very careful -- it does not atomically load the pte or anything that
+	 * is likely to be useful for you.
+	 */
+	pte_t pte;
+
+retry:
+	pte.pte_low = ptep->pte_low;
+	smp_rmb();
+	pte.pte_high = ptep->pte_high;
+	smp_rmb();
+	if (unlikely(pte.pte_low != ptep->pte_low))
+		goto retry;
+
+	return pte;
+}
+#define gup_get_pte gup_get_pte
+
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT;
+
+	prot |= _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
+	if (write)
+		prot |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
+	return __pte_access_permitted(pte, prot);
+}
+#elif defined(CONFIG_SUPERH64)
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
+
+	if (write)
+		prot |= _PAGE_WRITE;
+	return __pte_access_permitted(pte, prot);
+}
+#else
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER;
+
+	if (write)
+		prot |= _PAGE_RW;
+	return __pte_access_permitted(pte, prot);
+#endif
+
+#define pte_access_permitted pte_access_permitted
+
 /* arch/sh/mm/mmap.c */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index fbe5e79751b3..5051b38fd5b6 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -17,7 +17,7 @@ cacheops-$(CONFIG_CPU_SHX3)		+= cache-shx3.o
 obj-y			+= $(cacheops-y)
 
 mmu-y			:= nommu.o extable_32.o
-mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o gup.o ioremap.o kmap.o \
+mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o ioremap.o kmap.o \
 			   pgtable.o tlbex_$(BITS).o tlbflush_$(BITS).o
 
 obj-y			+= $(mmu-y)
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c
deleted file mode 100644
index 277c882f7489..000000000000
--- a/arch/sh/mm/gup.c
+++ /dev/null
@@ -1,277 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for SuperH
- *
- * Copyright (C) 2009 - 2010  Paul Mundt
- *
- * Cloned from the x86 and PowerPC versions, by:
- *
- *	Copyright (C) 2008 Nick Piggin
- *	Copyright (C) 2008 Novell Inc.
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#ifndef CONFIG_X2TLB
-	return READ_ONCE(*ptep);
-#else
-	/*
-	 * With get_user_pages_fast, we walk down the pagetables without
-	 * taking any locks.  For this we would like to load the pointers
-	 * atomically, but that is not possible with 64-bit PTEs.  What
-	 * we do have is the guarantee that a pte will only either go
-	 * from not present to present, or present to not present or both
-	 * -- it will not switch to a completely different present page
-	 * without a TLB flush in between; something that we are blocking
-	 * by holding interrupts off.
-	 *
-	 * Setting ptes from not present to present goes:
-	 * ptep->pte_high = h;
-	 * smp_wmb();
-	 * ptep->pte_low = l;
-	 *
-	 * And present to not present goes:
-	 * ptep->pte_low = 0;
-	 * smp_wmb();
-	 * ptep->pte_high = 0;
-	 *
-	 * We must ensure here that the load of pte_low sees l iff pte_high
-	 * sees h. We load pte_high *after* loading pte_low, which ensures we
-	 * don't see an older value of pte_high.  *Then* we recheck pte_low,
-	 * which ensures that we haven't picked up a changed pte high. We might
-	 * have got rubbish values from pte_low and pte_high, but we are
-	 * guaranteed that pte_low will not have the present bit set *unless*
-	 * it is 'l'. And get_user_pages_fast only operates on present ptes, so
-	 * we're safe.
-	 *
-	 * gup_get_pte should not be used or copied outside gup.c without being
-	 * very careful -- it does not atomically load the pte or anything that
-	 * is likely to be useful for you.
-	 */
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#endif
-}
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	u64 mask, result;
-	pte_t *ptep;
-
-#ifdef CONFIG_X2TLB
-	result = _PAGE_PRESENT | _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
-	if (write)
-		result |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
-#elif defined(CONFIG_SUPERH64)
-	result = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
-	if (write)
-		result |= _PAGE_WRITE;
-#else
-	result = _PAGE_PRESENT | _PAGE_USER;
-	if (write)
-		result |= _PAGE_RW;
-#endif
-
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if ((pte_val(pte) & mask) != result) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		__flush_anon_page(page, addr);
-		flush_dcache_page(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-	pte_unmap(ptep - 1);
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (!gup_pte_range(pmd, addr, next, write, pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start)
-		goto slow_irqon;
-
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-slow_irqon:
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

[PATCH 3/6] sh: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sh code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/Kconfig               |   1 +
 arch/sh/include/asm/pgtable.h |  85 +++++++++++
 arch/sh/mm/Makefile           |   2 +-
 arch/sh/mm/gup.c              | 277 ----------------------------------
 4 files changed, 87 insertions(+), 278 deletions(-)
 delete mode 100644 arch/sh/mm/gup.c

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index b77f512bb176..2fd8c12ca128 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,6 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
+	select HAVE_GENERIC_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 3587103afe59..d3c177144f90 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -149,6 +149,91 @@ extern void paging_init(void);
 extern void page_table_range_init(unsigned long start, unsigned long end,
 				  pgd_t *pgd);
 
+static inline bool __pte_access_permitted(pte_t pte, u64 prot)
+{
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot;
+}
+
+#ifdef CONFIG_X2TLB
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	/*
+	 * With get_user_pages_fast, we walk down the pagetables without
+	 * taking any locks.  For this we would like to load the pointers
+	 * atomically, but that is not possible with 64-bit PTEs.  What
+	 * we do have is the guarantee that a pte will only either go
+	 * from not present to present, or present to not present or both
+	 * -- it will not switch to a completely different present page
+	 * without a TLB flush in between; something that we are blocking
+	 * by holding interrupts off.
+	 *
+	 * Setting ptes from not present to present goes:
+	 * ptep->pte_high = h;
+	 * smp_wmb();
+	 * ptep->pte_low = l;
+	 *
+	 * And present to not present goes:
+	 * ptep->pte_low = 0;
+	 * smp_wmb();
+	 * ptep->pte_high = 0;
+	 *
+	 * We must ensure here that the load of pte_low sees l iff pte_high
+	 * sees h. We load pte_high *after* loading pte_low, which ensures we
+	 * don't see an older value of pte_high.  *Then* we recheck pte_low,
+	 * which ensures that we haven't picked up a changed pte high. We might
+	 * have got rubbish values from pte_low and pte_high, but we are
+	 * guaranteed that pte_low will not have the present bit set *unless*
+	 * it is 'l'. And get_user_pages_fast only operates on present ptes, so
+	 * we're safe.
+	 *
+	 * gup_get_pte should not be used or copied outside gup.c without being
+	 * very careful -- it does not atomically load the pte or anything that
+	 * is likely to be useful for you.
+	 */
+	pte_t pte;
+
+retry:
+	pte.pte_low = ptep->pte_low;
+	smp_rmb();
+	pte.pte_high = ptep->pte_high;
+	smp_rmb();
+	if (unlikely(pte.pte_low != ptep->pte_low))
+		goto retry;
+
+	return pte;
+}
+#define gup_get_pte gup_get_pte
+
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT;
+
+	prot |= _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
+	if (write)
+		prot |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
+	return __pte_access_permitted(pte, prot);
+}
+#elif defined(CONFIG_SUPERH64)
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
+
+	if (write)
+		prot |= _PAGE_WRITE;
+	return __pte_access_permitted(pte, prot);
+}
+#else
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER;
+
+	if (write)
+		prot |= _PAGE_RW;
+	return __pte_access_permitted(pte, prot);
+#endif
+
+#define pte_access_permitted pte_access_permitted
+
 /* arch/sh/mm/mmap.c */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index fbe5e79751b3..5051b38fd5b6 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -17,7 +17,7 @@ cacheops-$(CONFIG_CPU_SHX3)		+= cache-shx3.o
 obj-y			+= $(cacheops-y)
 
 mmu-y			:= nommu.o extable_32.o
-mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o gup.o ioremap.o kmap.o \
+mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o ioremap.o kmap.o \
 			   pgtable.o tlbex_$(BITS).o tlbflush_$(BITS).o
 
 obj-y			+= $(mmu-y)
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c
deleted file mode 100644
index 277c882f7489..000000000000
--- a/arch/sh/mm/gup.c
+++ /dev/null
@@ -1,277 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for SuperH
- *
- * Copyright (C) 2009 - 2010  Paul Mundt
- *
- * Cloned from the x86 and PowerPC versions, by:
- *
- *	Copyright (C) 2008 Nick Piggin
- *	Copyright (C) 2008 Novell Inc.
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#ifndef CONFIG_X2TLB
-	return READ_ONCE(*ptep);
-#else
-	/*
-	 * With get_user_pages_fast, we walk down the pagetables without
-	 * taking any locks.  For this we would like to load the pointers
-	 * atomically, but that is not possible with 64-bit PTEs.  What
-	 * we do have is the guarantee that a pte will only either go
-	 * from not present to present, or present to not present or both
-	 * -- it will not switch to a completely different present page
-	 * without a TLB flush in between; something that we are blocking
-	 * by holding interrupts off.
-	 *
-	 * Setting ptes from not present to present goes:
-	 * ptep->pte_high = h;
-	 * smp_wmb();
-	 * ptep->pte_low = l;
-	 *
-	 * And present to not present goes:
-	 * ptep->pte_low = 0;
-	 * smp_wmb();
-	 * ptep->pte_high = 0;
-	 *
-	 * We must ensure here that the load of pte_low sees l iff pte_high
-	 * sees h. We load pte_high *after* loading pte_low, which ensures we
-	 * don't see an older value of pte_high.  *Then* we recheck pte_low,
-	 * which ensures that we haven't picked up a changed pte high. We might
-	 * have got rubbish values from pte_low and pte_high, but we are
-	 * guaranteed that pte_low will not have the present bit set *unless*
-	 * it is 'l'. And get_user_pages_fast only operates on present ptes, so
-	 * we're safe.
-	 *
-	 * gup_get_pte should not be used or copied outside gup.c without being
-	 * very careful -- it does not atomically load the pte or anything that
-	 * is likely to be useful for you.
-	 */
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#endif
-}
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	u64 mask, result;
-	pte_t *ptep;
-
-#ifdef CONFIG_X2TLB
-	result = _PAGE_PRESENT | _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
-	if (write)
-		result |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
-#elif defined(CONFIG_SUPERH64)
-	result = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
-	if (write)
-		result |= _PAGE_WRITE;
-#else
-	result = _PAGE_PRESENT | _PAGE_USER;
-	if (write)
-		result |= _PAGE_RW;
-#endif
-
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if ((pte_val(pte) & mask) != result) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		__flush_anon_page(page, addr);
-		flush_dcache_page(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-	pte_unmap(ptep - 1);
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (!gup_pte_range(pmd, addr, next, write, pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start)
-		goto slow_irqon;
-
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-slow_irqon:
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

[PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Christoph Hellwig]

This will allow sparc64 to override its ADI tags for
get_user_pages and get_user_pages_fast.  I have no idea why this
is not required for plain old get_user_pages, but it keeps the
existing sparc64 behavior.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index f173fcbaf1b2..1c21ecfbf38b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2117,6 +2117,10 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
 	} while (pgdp++, addr = next, addr != end);
 }
 
+#ifndef gup_fixup_start_addr
+#define gup_fixup_start_addr(start)	(start)
+#endif
+
 #ifndef gup_fast_permitted
 /*
  * Check if it's allowed to use __get_user_pages_fast() for the range, or
@@ -2145,7 +2149,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	unsigned long flags;
 	int nr = 0;
 
-	start &= PAGE_MASK;
+	start = gup_fixup_start_addr(start) & PAGE_MASK;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
@@ -2218,7 +2222,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
-	start &= PAGE_MASK;
+	start = gup_fixup_start_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
-- 
2.20.1

[PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Christoph Hellwig]

This will allow sparc64 to override its ADI tags for
get_user_pages and get_user_pages_fast.  I have no idea why this
is not required for plain old get_user_pages, but it keeps the
existing sparc64 behavior.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index f173fcbaf1b2..1c21ecfbf38b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2117,6 +2117,10 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
 	} while (pgdp++, addr = next, addr != end);
 }
 
+#ifndef gup_fixup_start_addr
+#define gup_fixup_start_addr(start)	(start)
+#endif
+
 #ifndef gup_fast_permitted
 /*
  * Check if it's allowed to use __get_user_pages_fast() for the range, or
@@ -2145,7 +2149,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	unsigned long flags;
 	int nr = 0;
 
-	start &= PAGE_MASK;
+	start = gup_fixup_start_addr(start) & PAGE_MASK;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
@@ -2218,7 +2222,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
-	start &= PAGE_MASK;
+	start = gup_fixup_start_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
-- 
2.20.1

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Linus Torvalds]

[ Adding Khalid, who added the sparc64 code ]

On Sat, May 25, 2019 at 6:32 AM Christoph Hellwig <hch@lst.de> wrote:
>
> This will allow sparc64 to override its ADI tags for
> get_user_pages and get_user_pages_fast.  I have no idea why this
> is not required for plain old get_user_pages, but it keeps the
> existing sparc64 behavior.

This is actually generic. ARM64 has tagged pointers too. Right now the
system call interfaces are all supposed to mask off the tags, but
there's been noise about having the kernel understand them.

That said:

> +#ifndef gup_fixup_start_addr
> +#define gup_fixup_start_addr(start)    (start)
> +#endif

I'd rather name this much more specifically (ie make it very much
about "clean up pointer tags") and I'm also not clear on why sparc64
actually wants this. I thought the sparc64 rules were the same as the
(current) arm64 rules: any addresses passed to the kernel have to be
the non-tagged ones.

As you say, nothing *else* in the kernel does that address cleanup,
why should get_user_pages_fast() do it?

David? Khalid? Why does sparc64 actually need this? It looks like the
generic get_user_pages() doesn't do it.

                Linus

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Linus Torvalds]

[ Adding Khalid, who added the sparc64 code ]

On Sat, May 25, 2019 at 6:32 AM Christoph Hellwig <hch@lst.de> wrote:
>
> This will allow sparc64 to override its ADI tags for
> get_user_pages and get_user_pages_fast.  I have no idea why this
> is not required for plain old get_user_pages, but it keeps the
> existing sparc64 behavior.

This is actually generic. ARM64 has tagged pointers too. Right now the
system call interfaces are all supposed to mask off the tags, but
there's been noise about having the kernel understand them.

That said:

> +#ifndef gup_fixup_start_addr
> +#define gup_fixup_start_addr(start)    (start)
> +#endif

I'd rather name this much more specifically (ie make it very much
about "clean up pointer tags") and I'm also not clear on why sparc64
actually wants this. I thought the sparc64 rules were the same as the
(current) arm64 rules: any addresses passed to the kernel have to be
the non-tagged ones.

As you say, nothing *else* in the kernel does that address cleanup,
why should get_user_pages_fast() do it?

David? Khalid? Why does sparc64 actually need this? It looks like the
generic get_user_pages() doesn't do it.

                Linus

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Linus Torvalds]

[ Adding Khalid, who added the sparc64 code ]

On Sat, May 25, 2019 at 6:32 AM Christoph Hellwig <hch@lst.de> wrote:
>
> This will allow sparc64 to override its ADI tags for
> get_user_pages and get_user_pages_fast.  I have no idea why this
> is not required for plain old get_user_pages, but it keeps the
> existing sparc64 behavior.

This is actually generic. ARM64 has tagged pointers too. Right now the
system call interfaces are all supposed to mask off the tags, but
there's been noise about having the kernel understand them.

That said:

> +#ifndef gup_fixup_start_addr
> +#define gup_fixup_start_addr(start)    (start)
> +#endif

I'd rather name this much more specifically (ie make it very much
about "clean up pointer tags") and I'm also not clear on why sparc64
actually wants this. I thought the sparc64 rules were the same as the
(current) arm64 rules: any addresses passed to the kernel have to be
the non-tagged ones.

As you say, nothing *else* in the kernel does that address cleanup,
why should get_user_pages_fast() do it?

David? Khalid? Why does sparc64 actually need this? It looks like the
generic get_user_pages() doesn't do it.

                Linus

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Khalid Aziz]

On 5/25/19 11:05 AM, Linus Torvalds wrote:
> [ Adding Khalid, who added the sparc64 code ]
> 
> On Sat, May 25, 2019 at 6:32 AM Christoph Hellwig <hch@lst.de> wrote:
>>
>> This will allow sparc64 to override its ADI tags for
>> get_user_pages and get_user_pages_fast.  I have no idea why this
>> is not required for plain old get_user_pages, but it keeps the
>> existing sparc64 behavior.
> 
> This is actually generic. ARM64 has tagged pointers too. Right now the
> system call interfaces are all supposed to mask off the tags, but
> there's been noise about having the kernel understand them.
> 
> That said:
> 
>> +#ifndef gup_fixup_start_addr
>> +#define gup_fixup_start_addr(start)    (start)
>> +#endif
> 
> I'd rather name this much more specifically (ie make it very much
> about "clean up pointer tags") and I'm also not clear on why sparc64
> actually wants this. I thought the sparc64 rules were the same as the
> (current) arm64 rules: any addresses passed to the kernel have to be
> the non-tagged ones.
> 
> As you say, nothing *else* in the kernel does that address cleanup,
> why should get_user_pages_fast() do it?
> 
> David? Khalid? Why does sparc64 actually need this? It looks like the
> generic get_user_pages() doesn't do it.
> 


There is another discussion going on about tagged pointers on ARM64 and
intersection with sparc64 code. I agree there is a generic need to mask
off tags for kernel use now that ARM64 is also looking into supporting
memory tagging. The need comes from sparc64 not storing tagged address
in VMAs. It is not practical to store tagged addresses in VMAs because
manipulation of address tags is done entirely in userspace on sparc64.
Userspace is free to change tags on an address range at any time without
involving kernel and constantly rotating tags is actually a security
feature even. This makes it impractical for kernel to try to keep up
with constantly changing tagged addresses in VMAs. Untagged addresses in
VMAs means any find_vma() and brethren calls need to be passed an
untagged address.

On sparc64, my intent was to support address tagging for dynamically
allocated data buffers only (malloc, mmap and shm specifically) and not
for any generic system calls which limited the scope and amount of
untagging needed in the kernel. ARM64 is working to add transparent
tagged address support at C library level. Adding tagged addresses to C
library requires every possible call into kernel to either handle tagged
addresses or untag address at some point. Andrey found out it is not as
easy as untagging addresses in functions that search through vma.
Callers of find_vma() and others tend to do address arithmetic on the
address stored in vma that is returned. This requires a more complex
solution than just stripping tags in vma lookup routines.

Since untagging addresses is a generic need required for far more than
gup, I prefer the way Andrey wrote it -
<https://patchwork.kernel.org/patch/10923637/>

--
Khalid

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Khalid Aziz]

On 5/25/19 11:05 AM, Linus Torvalds wrote:
> [ Adding Khalid, who added the sparc64 code ]
> 
> On Sat, May 25, 2019 at 6:32 AM Christoph Hellwig <hch@lst.de> wrote:
>>
>> This will allow sparc64 to override its ADI tags for
>> get_user_pages and get_user_pages_fast.  I have no idea why this
>> is not required for plain old get_user_pages, but it keeps the
>> existing sparc64 behavior.
> 
> This is actually generic. ARM64 has tagged pointers too. Right now the
> system call interfaces are all supposed to mask off the tags, but
> there's been noise about having the kernel understand them.
> 
> That said:
> 
>> +#ifndef gup_fixup_start_addr
>> +#define gup_fixup_start_addr(start)    (start)
>> +#endif
> 
> I'd rather name this much more specifically (ie make it very much
> about "clean up pointer tags") and I'm also not clear on why sparc64
> actually wants this. I thought the sparc64 rules were the same as the
> (current) arm64 rules: any addresses passed to the kernel have to be
> the non-tagged ones.
> 
> As you say, nothing *else* in the kernel does that address cleanup,
> why should get_user_pages_fast() do it?
> 
> David? Khalid? Why does sparc64 actually need this? It looks like the
> generic get_user_pages() doesn't do it.
> 


There is another discussion going on about tagged pointers on ARM64 and
intersection with sparc64 code. I agree there is a generic need to mask
off tags for kernel use now that ARM64 is also looking into supporting
memory tagging. The need comes from sparc64 not storing tagged address
in VMAs. It is not practical to store tagged addresses in VMAs because
manipulation of address tags is done entirely in userspace on sparc64.
Userspace is free to change tags on an address range at any time without
involving kernel and constantly rotating tags is actually a security
feature even. This makes it impractical for kernel to try to keep up
with constantly changing tagged addresses in VMAs. Untagged addresses in
VMAs means any find_vma() and brethren calls need to be passed an
untagged address.

On sparc64, my intent was to support address tagging for dynamically
allocated data buffers only (malloc, mmap and shm specifically) and not
for any generic system calls which limited the scope and amount of
untagging needed in the kernel. ARM64 is working to add transparent
tagged address support at C library level. Adding tagged addresses to C
library requires every possible call into kernel to either handle tagged
addresses or untag address at some point. Andrey found out it is not as
easy as untagging addresses in functions that search through vma.
Callers of find_vma() and others tend to do address arithmetic on the
address stored in vma that is returned. This requires a more complex
solution than just stripping tags in vma lookup routines.

Since untagging addresses is a generic need required for far more than
gup, I prefer the way Andrey wrote it -
<https://patchwork.kernel.org/patch/10923637/>

--
Khalid

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Christoph Hellwig]

On Tue, May 28, 2019 at 09:57:25AM -0600, Khalid Aziz wrote:
> Since untagging addresses is a generic need required for far more than
> gup, I prefer the way Andrey wrote it -
> <https://patchwork.kernel.org/patch/10923637/>

Linus, what do you think of picking up that trivial prep patch for
5.2?  That way the arm64 and get_user_pages series can progress
independently for 5.3.

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Christoph Hellwig]

On Tue, May 28, 2019 at 09:57:25AM -0600, Khalid Aziz wrote:
> Since untagging addresses is a generic need required for far more than
> gup, I prefer the way Andrey wrote it -
> <https://patchwork.kernel.org/patch/10923637/>

Linus, what do you think of picking up that trivial prep patch for
5.2?  That way the arm64 and get_user_pages series can progress
independently for 5.3.

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Catalin Marinas]

Hi Christoph,

On Sat, 25 May 2019 at 14:33, Christoph Hellwig <hch@lst.de> wrote:
> diff --git a/mm/gup.c b/mm/gup.c
> index f173fcbaf1b2..1c21ecfbf38b 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2117,6 +2117,10 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>         } while (pgdp++, addr = next, addr != end);
>  }
>
> +#ifndef gup_fixup_start_addr
> +#define gup_fixup_start_addr(start)    (start)
> +#endif

As you pointed out in a subsequent reply, we could use the
untagged_addr() macro from Andrey (or a shorter "untag_addr" if you
want it to look like a verb).

>  #ifndef gup_fast_permitted
>  /*
>   * Check if it's allowed to use __get_user_pages_fast() for the range, or
> @@ -2145,7 +2149,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>         unsigned long flags;
>         int nr = 0;
>
> -       start &= PAGE_MASK;
> +       start = gup_fixup_start_addr(start) & PAGE_MASK;
>         len = (unsigned long) nr_pages << PAGE_SHIFT;
>         end = start + len;
>
> @@ -2218,7 +2222,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
>         unsigned long addr, len, end;
>         int nr = 0, ret = 0;
>
> -       start &= PAGE_MASK;
> +       start = gup_fixup_start_addr(start) & PAGE_MASK;
>         addr = start;
>         len = (unsigned long) nr_pages << PAGE_SHIFT;
>         end = start + len;

In Andrey's patch [1] we don't fix __get_user_pages_fast(), only
__get_user_pages() as it needs to do a find_vma() search. I wonder
whether this is actually necessary for the *_fast() versions. If the
top byte is non-zero (i.e. tagged address), 'end' would also have the
same tag. The page table macros like pgd_index() and pgd_addr_end()
already take care of masking out the top bits (at least for arm64)
since they need to work on kernel address with the top bits all 1. So
gup_pgd_range() should cope with tagged addresses already.

[1] https://lore.kernel.org/lkml/d234cd71774f35229bdfc0a793c34d6712b73093.1557160186.git.andreyknvl@google.com/

-- 
Catalin

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Catalin Marinas]

Hi Christoph,

On Sat, 25 May 2019 at 14:33, Christoph Hellwig <hch@lst.de> wrote:
> diff --git a/mm/gup.c b/mm/gup.c
> index f173fcbaf1b2..1c21ecfbf38b 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2117,6 +2117,10 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>         } while (pgdp++, addr = next, addr != end);
>  }
>
> +#ifndef gup_fixup_start_addr
> +#define gup_fixup_start_addr(start)    (start)
> +#endif

As you pointed out in a subsequent reply, we could use the
untagged_addr() macro from Andrey (or a shorter "untag_addr" if you
want it to look like a verb).

>  #ifndef gup_fast_permitted
>  /*
>   * Check if it's allowed to use __get_user_pages_fast() for the range, or
> @@ -2145,7 +2149,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>         unsigned long flags;
>         int nr = 0;
>
> -       start &= PAGE_MASK;
> +       start = gup_fixup_start_addr(start) & PAGE_MASK;
>         len = (unsigned long) nr_pages << PAGE_SHIFT;
>         end = start + len;
>
> @@ -2218,7 +2222,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
>         unsigned long addr, len, end;
>         int nr = 0, ret = 0;
>
> -       start &= PAGE_MASK;
> +       start = gup_fixup_start_addr(start) & PAGE_MASK;
>         addr = start;
>         len = (unsigned long) nr_pages << PAGE_SHIFT;
>         end = start + len;

In Andrey's patch [1] we don't fix __get_user_pages_fast(), only
__get_user_pages() as it needs to do a find_vma() search. I wonder
whether this is actually necessary for the *_fast() versions. If the
top byte is non-zero (i.e. tagged address), 'end' would also have the
same tag. The page table macros like pgd_index() and pgd_addr_end()
already take care of masking out the top bits (at least for arm64)
since they need to work on kernel address with the top bits all 1. So
gup_pgd_range() should cope with tagged addresses already.

[1] https://lore.kernel.org/lkml/d234cd71774f35229bdfc0a793c34d6712b73093.1557160186.git.andreyknvl@google.com/

-- 
Catalin

Re: [PATCH 4/6] mm: add a gup_fixup_start_addr hook

[Catalin Marinas]

Hi Christoph,

On Sat, 25 May 2019 at 14:33, Christoph Hellwig <hch@lst.de> wrote:
> diff --git a/mm/gup.c b/mm/gup.c
> index f173fcbaf1b2..1c21ecfbf38b 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2117,6 +2117,10 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>         } while (pgdp++, addr = next, addr != end);
>  }
>
> +#ifndef gup_fixup_start_addr
> +#define gup_fixup_start_addr(start)    (start)
> +#endif

As you pointed out in a subsequent reply, we could use the
untagged_addr() macro from Andrey (or a shorter "untag_addr" if you
want it to look like a verb).

>  #ifndef gup_fast_permitted
>  /*
>   * Check if it's allowed to use __get_user_pages_fast() for the range, or
> @@ -2145,7 +2149,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>         unsigned long flags;
>         int nr = 0;
>
> -       start &= PAGE_MASK;
> +       start = gup_fixup_start_addr(start) & PAGE_MASK;
>         len = (unsigned long) nr_pages << PAGE_SHIFT;
>         end = start + len;
>
> @@ -2218,7 +2222,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
>         unsigned long addr, len, end;
>         int nr = 0, ret = 0;
>
> -       start &= PAGE_MASK;
> +       start = gup_fixup_start_addr(start) & PAGE_MASK;
>         addr = start;
>         len = (unsigned long) nr_pages << PAGE_SHIFT;
>         end = start + len;

In Andrey's patch [1] we don't fix __get_user_pages_fast(), only
__get_user_pages() as it needs to do a find_vma() search. I wonder
whether this is actually necessary for the *_fast() versions. If the
top byte is non-zero (i.e. tagged address), 'end' would also have the
same tag. The page table macros like pgd_index() and pgd_addr_end()
already take care of masking out the top bits (at least for arm64)
since they need to work on kernel address with the top bits all 1. So
gup_pgd_range() should cope with tagged addresses already.

[1] https://lore.kernel.org/lkml/d234cd71774f35229bdfc0a793c34d6712b73093.1557160186.git.andreyknvl@google.com/

-- 
Catalin

[PATCH 5/6] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sparc64 code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/Kconfig                  |   1 +
 arch/sparc/include/asm/pgtable_64.h |  40 ++++
 arch/sparc/mm/Makefile              |   2 +-
 arch/sparc/mm/gup.c                 | 340 ----------------------------
 4 files changed, 42 insertions(+), 341 deletions(-)
 delete mode 100644 arch/sparc/mm/gup.c

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 26ab6f5bbaaf..22435471f942 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,6 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
+	select HAVE_GENERIC_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 22500c3be7a9..753d1417bae1 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1075,6 +1075,46 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 }
 #define io_remap_pfn_range io_remap_pfn_range 
 
+static inline unsigned long gup_fixup_start_addr(unsigned long start)
+{
+	if (adi_capable()) {
+		long addr = start;
+
+		/* If userspace has passed a versioned address, kernel
+		 * will not find it in the VMAs since it does not store
+		 * the version tags in the list of VMAs. Storing version
+		 * tags in list of VMAs is impractical since they can be
+		 * changed any time from userspace without dropping into
+		 * kernel. Any address search in VMAs will be done with
+		 * non-versioned addresses. Ensure the ADI version bits
+		 * are dropped here by sign extending the last bit before
+		 * ADI bits. IOMMU does not implement version tags.
+		 */
+		return (addr << (long)adi_nbits()) >> (long)adi_nbits();
+	}
+
+	return start;
+}
+#define gup_fixup_start_addr gup_fixup_start_addr
+
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot;
+
+	if (tlb_type = hypervisor) {
+		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
+		if (prot)
+			prot |= _PAGE_WRITE_4V;
+	} else {
+		prot = _PAGE_PRESENT_4U | _PAGE_P_4U;
+		if (write)
+			prot |= _PAGE_WRITE_4U;
+	}
+
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) = prot;
+}
+#define pte_access_permitted pte_access_permitted
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
diff --git a/arch/sparc/mm/Makefile b/arch/sparc/mm/Makefile
index d39075b1e3b7..b078205b70e0 100644
--- a/arch/sparc/mm/Makefile
+++ b/arch/sparc/mm/Makefile
@@ -5,7 +5,7 @@
 asflags-y := -ansi
 ccflags-y := -Werror
 
-obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o gup.o
+obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o
 obj-y                   += fault_$(BITS).o
 obj-y                   += init_$(BITS).o
 obj-$(CONFIG_SPARC32)   += extable.o srmmu.o iommu.o io-unit.o
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
deleted file mode 100644
index 1e770a517d4a..000000000000
--- a/arch/sparc/mm/gup.c
+++ /dev/null
@@ -1,340 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for sparc, cribbed from powerpc
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- */
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/pagemap.h>
-#include <linux/rwsem.h>
-#include <asm/pgtable.h>
-#include <asm/adi.h>
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long mask, result;
-	pte_t *ptep;
-
-	if (tlb_type = hypervisor) {
-		result = _PAGE_PRESENT_4V|_PAGE_P_4V;
-		if (write)
-			result |= _PAGE_WRITE_4V;
-	} else {
-		result = _PAGE_PRESENT_4U|_PAGE_P_4U;
-		if (write)
-			result |= _PAGE_WRITE_4U;
-	}
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_kernel(&pmd, addr);
-	do {
-		struct page *page, *head;
-		pte_t pte = *ptep;
-
-		if ((pte_val(pte) & mask) != result)
-			return 0;
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-		/* The hugepage case is simplified on sparc64 because
-		 * we encode the sub-page pfn offsets into the
-		 * hugepage PTEs.  We could optimize this in the future
-		 * use page_cache_add_speculative() for the hugepage case.
-		 */
-		page = pte_page(pte);
-		head = compound_head(page);
-		if (!page_cache_get_speculative(head))
-			return 0;
-		if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-			put_page(head);
-			return 0;
-		}
-
-		pages[*nr] = page;
-		(*nr)++;
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pmd_val(pmd) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pmd_write(pmd))
-		return 0;
-
-	refs = 0;
-	page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pud_val(pud) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pud_write(pud))
-		return 0;
-
-	refs = 0;
-	page = pud_page(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pud_val(pud) != pud_val(*pudp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_large(pmd))) {
-			if (!gup_huge_pmd(pmdp, pmd, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pte_range(pmd, addr, next, write,
-					  pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_large(pud))) {
-			if (!gup_huge_pud(pudp, pud, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next, flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implement version tags.
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implements version tags,
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch size
-	 * will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables from being freed on sparc.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the the page and take a ref on it.
-	 */
-	local_irq_disable();
-
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

[PATCH 5/6] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sparc64 code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/Kconfig                  |   1 +
 arch/sparc/include/asm/pgtable_64.h |  40 ++++
 arch/sparc/mm/Makefile              |   2 +-
 arch/sparc/mm/gup.c                 | 340 ----------------------------
 4 files changed, 42 insertions(+), 341 deletions(-)
 delete mode 100644 arch/sparc/mm/gup.c

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 26ab6f5bbaaf..22435471f942 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,6 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
+	select HAVE_GENERIC_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 22500c3be7a9..753d1417bae1 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1075,6 +1075,46 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 }
 #define io_remap_pfn_range io_remap_pfn_range 
 
+static inline unsigned long gup_fixup_start_addr(unsigned long start)
+{
+	if (adi_capable()) {
+		long addr = start;
+
+		/* If userspace has passed a versioned address, kernel
+		 * will not find it in the VMAs since it does not store
+		 * the version tags in the list of VMAs. Storing version
+		 * tags in list of VMAs is impractical since they can be
+		 * changed any time from userspace without dropping into
+		 * kernel. Any address search in VMAs will be done with
+		 * non-versioned addresses. Ensure the ADI version bits
+		 * are dropped here by sign extending the last bit before
+		 * ADI bits. IOMMU does not implement version tags.
+		 */
+		return (addr << (long)adi_nbits()) >> (long)adi_nbits();
+	}
+
+	return start;
+}
+#define gup_fixup_start_addr gup_fixup_start_addr
+
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot;
+
+	if (tlb_type == hypervisor) {
+		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
+		if (prot)
+			prot |= _PAGE_WRITE_4V;
+	} else {
+		prot = _PAGE_PRESENT_4U | _PAGE_P_4U;
+		if (write)
+			prot |= _PAGE_WRITE_4U;
+	}
+
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot;
+}
+#define pte_access_permitted pte_access_permitted
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
diff --git a/arch/sparc/mm/Makefile b/arch/sparc/mm/Makefile
index d39075b1e3b7..b078205b70e0 100644
--- a/arch/sparc/mm/Makefile
+++ b/arch/sparc/mm/Makefile
@@ -5,7 +5,7 @@
 asflags-y := -ansi
 ccflags-y := -Werror
 
-obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o gup.o
+obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o
 obj-y                   += fault_$(BITS).o
 obj-y                   += init_$(BITS).o
 obj-$(CONFIG_SPARC32)   += extable.o srmmu.o iommu.o io-unit.o
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
deleted file mode 100644
index 1e770a517d4a..000000000000
--- a/arch/sparc/mm/gup.c
+++ /dev/null
@@ -1,340 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for sparc, cribbed from powerpc
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- */
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/pagemap.h>
-#include <linux/rwsem.h>
-#include <asm/pgtable.h>
-#include <asm/adi.h>
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long mask, result;
-	pte_t *ptep;
-
-	if (tlb_type == hypervisor) {
-		result = _PAGE_PRESENT_4V|_PAGE_P_4V;
-		if (write)
-			result |= _PAGE_WRITE_4V;
-	} else {
-		result = _PAGE_PRESENT_4U|_PAGE_P_4U;
-		if (write)
-			result |= _PAGE_WRITE_4U;
-	}
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_kernel(&pmd, addr);
-	do {
-		struct page *page, *head;
-		pte_t pte = *ptep;
-
-		if ((pte_val(pte) & mask) != result)
-			return 0;
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-		/* The hugepage case is simplified on sparc64 because
-		 * we encode the sub-page pfn offsets into the
-		 * hugepage PTEs.  We could optimize this in the future
-		 * use page_cache_add_speculative() for the hugepage case.
-		 */
-		page = pte_page(pte);
-		head = compound_head(page);
-		if (!page_cache_get_speculative(head))
-			return 0;
-		if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-			put_page(head);
-			return 0;
-		}
-
-		pages[*nr] = page;
-		(*nr)++;
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pmd_val(pmd) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pmd_write(pmd))
-		return 0;
-
-	refs = 0;
-	page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pud_val(pud) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pud_write(pud))
-		return 0;
-
-	refs = 0;
-	page = pud_page(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pud_val(pud) != pud_val(*pudp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_large(pmd))) {
-			if (!gup_huge_pmd(pmdp, pmd, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pte_range(pmd, addr, next, write,
-					  pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_large(pud))) {
-			if (!gup_huge_pud(pudp, pud, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next, flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implement version tags.
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implements version tags,
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch size
-	 * will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables from being freed on sparc.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the the page and take a ref on it.
-	 */
-	local_irq_disable();
-
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

Re: [PATCH 5/6] sparc64: use the generic get_user_pages_fast code

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Sat, 25 May 2019 15:32:02 +0200

> The sparc64 code is mostly equivalent to the generic one, minus various
> bugfixes and two arch overrides that this patch adds to pgtable.h.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Acked-by: David S. Miller <davem@davemloft.net>

Re: [PATCH 5/6] sparc64: use the generic get_user_pages_fast code

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Sat, 25 May 2019 15:32:02 +0200

> The sparc64 code is mostly equivalent to the generic one, minus various
> bugfixes and two arch overrides that this patch adds to pgtable.h.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Acked-by: David S. Miller <davem@davemloft.net>

[PATCH 6/6] mm: don't allow non-generic get_user_pages_fast implementations

[Christoph Hellwig]

Add an explicit ifdef instead of the weak functions for the stubs
so that we can't let new get_user_pages_fast implementation slip in.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/util.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/mm/util.c b/mm/util.c
index 91682a2090ee..74ae737ffd95 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -300,6 +300,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 }
 #endif
 
+#ifndef CONFIG_HAVE_GENERIC_GUP
 /*
  * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
  * back to the regular GUP.
@@ -308,8 +309,8 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
  * If the architecture does not support this function, simply return with no
  * pages pinned.
  */
-int __weak __get_user_pages_fast(unsigned long start,
-				 int nr_pages, int write, struct page **pages)
+int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
+		struct page **pages)
 {
 	return 0;
 }
@@ -339,13 +340,13 @@ EXPORT_SYMBOL_GPL(__get_user_pages_fast);
  * requested. If nr_pages is 0 or negative, returns 0. If no pages
  * were pinned, returns -errno.
  */
-int __weak get_user_pages_fast(unsigned long start,
-				int nr_pages, unsigned int gup_flags,
-				struct page **pages)
+int get_user_pages_fast(unsigned long start, int nr_pages,
+		unsigned int gup_flags, struct page **pages)
 {
 	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
 }
 EXPORT_SYMBOL_GPL(get_user_pages_fast);
+#endif /* !CONFIG_HAVE_GENERIC_GUP */
 
 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,
-- 
2.20.1

[PATCH 6/6] mm: don't allow non-generic get_user_pages_fast implementations

[Christoph Hellwig]

Add an explicit ifdef instead of the weak functions for the stubs
so that we can't let new get_user_pages_fast implementation slip in.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/util.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/mm/util.c b/mm/util.c
index 91682a2090ee..74ae737ffd95 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -300,6 +300,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 }
 #endif
 
+#ifndef CONFIG_HAVE_GENERIC_GUP
 /*
  * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
  * back to the regular GUP.
@@ -308,8 +309,8 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
  * If the architecture does not support this function, simply return with no
  * pages pinned.
  */
-int __weak __get_user_pages_fast(unsigned long start,
-				 int nr_pages, int write, struct page **pages)
+int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
+		struct page **pages)
 {
 	return 0;
 }
@@ -339,13 +340,13 @@ EXPORT_SYMBOL_GPL(__get_user_pages_fast);
  * requested. If nr_pages is 0 or negative, returns 0. If no pages
  * were pinned, returns -errno.
  */
-int __weak get_user_pages_fast(unsigned long start,
-				int nr_pages, unsigned int gup_flags,
-				struct page **pages)
+int get_user_pages_fast(unsigned long start, int nr_pages,
+		unsigned int gup_flags, struct page **pages)
 {
 	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
 }
 EXPORT_SYMBOL_GPL(get_user_pages_fast);
+#endif /* !CONFIG_HAVE_GENERIC_GUP */
 
 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,
-- 
2.20.1

Re: RFC: switch the remaining architectures to use generic GUP

[Linus Torvalds]

Looks good to me apart from the question about sparc64 (that you also
raised) and requesting that interface to be re-named if it is really
needed.

Let's just do it (but presumably for 5.3), and any architecture that
doesn't react to this and gets broken because it wasn't tested can get
fixed up later when/if they notice.

              Linus

Re: RFC: switch the remaining architectures to use generic GUP

[Linus Torvalds]

Looks good to me apart from the question about sparc64 (that you also
raised) and requesting that interface to be re-named if it is really
needed.

Let's just do it (but presumably for 5.3), and any architecture that
doesn't react to this and gets broken because it wasn't tested can get
fixed up later when/if they notice.

              Linus

Re: RFC: switch the remaining architectures to use generic GUP

[Linus Torvalds]

Looks good to me apart from the question about sparc64 (that you also
raised) and requesting that interface to be re-named if it is really
needed.

Let's just do it (but presumably for 5.3), and any architecture that
doesn't react to this and gets broken because it wasn't tested can get
fixed up later when/if they notice.

              Linus

Re: RFC: switch the remaining architectures to use generic GUP

[Christoph Hellwig]

On Sat, May 25, 2019 at 10:07:32AM -0700, Linus Torvalds wrote:
> Looks good to me apart from the question about sparc64 (that you also
> raised) and requesting that interface to be re-named if it is really
> needed.
> 
> Let's just do it (but presumably for 5.3), and any architecture that
> doesn't react to this and gets broken because it wasn't tested can get
> fixed up later when/if they notice.

FYI, my compile testing was very basic and a few issues showed up
from the build bot later on.  I'll keep the branch here uptodate
for now:

	http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/generic-gup

and won't resend until we make progress on the pointer tagging
thing.  I've also got a few follow on patches on top, so they might
be ready by then as well.

Re: RFC: switch the remaining architectures to use generic GUP

[Christoph Hellwig]

On Sat, May 25, 2019 at 10:07:32AM -0700, Linus Torvalds wrote:
> Looks good to me apart from the question about sparc64 (that you also
> raised) and requesting that interface to be re-named if it is really
> needed.
> 
> Let's just do it (but presumably for 5.3), and any architecture that
> doesn't react to this and gets broken because it wasn't tested can get
> fixed up later when/if they notice.

FYI, my compile testing was very basic and a few issues showed up
from the build bot later on.  I'll keep the branch here uptodate
for now:

	http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/generic-gup

and won't resend until we make progress on the pointer tagging
thing.  I've also got a few follow on patches on top, so they might
be ready by then as well.

RFC: switch the remaining architectures to use generic GUP v2

[Christoph Hellwig]

Hi Linus and maintainers,

below is a series to switch mips, sh and sparc64 to use the generic
GUP code so that we only have one codebase to touch for further
improvements to this code.  I don't have hardware for any of these
architectures, and generally no clue about their page table
management, so handle with care.

Changes since v1:
 - fix various issues found by the build bot
 - cherry pick and use the untagged_addr helper form Andrey
 - add various refactoring patches to share more code over architectures
 - move the powerpc hugepd code to mm/gup.c and sync it with the generic
   hup semantics

RFC: switch the remaining architectures to use generic GUP v2

[Christoph Hellwig]

Hi Linus and maintainers,

below is a series to switch mips, sh and sparc64 to use the generic
GUP code so that we only have one codebase to touch for further
improvements to this code.  I don't have hardware for any of these
architectures, and generally no clue about their page table
management, so handle with care.

Changes since v1:
 - fix various issues found by the build bot
 - cherry pick and use the untagged_addr helper form Andrey
 - add various refactoring patches to share more code over architectures
 - move the powerpc hugepd code to mm/gup.c and sync it with the generic
   hup semantics

RFC: switch the remaining architectures to use generic GUP v2

[Christoph Hellwig]

Hi Linus and maintainers,

below is a series to switch mips, sh and sparc64 to use the generic
GUP code so that we only have one codebase to touch for further
improvements to this code.  I don't have hardware for any of these
architectures, and generally no clue about their page table
management, so handle with care.

Changes since v1:
 - fix various issues found by the build bot
 - cherry pick and use the untagged_addr helper form Andrey
 - add various refactoring patches to share more code over architectures
 - move the powerpc hugepd code to mm/gup.c and sync it with the generic
   hup semantics

[PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Christoph Hellwig]

From: Andrey Konovalov <andreyknvl@google.com>

To allow arm64 syscalls to accept tagged pointers from userspace, we must
untag them when they are passed to the kernel. Since untagging is done in
generic parts of the kernel, the untagged_addr macro needs to be defined
for all architectures.

Define it as a noop for architectures other than arm64.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e8834ac32b7..949d43e9c0b6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 
+#ifndef untagged_addr
+#define untagged_addr(addr) (addr)
+#endif
+
 #ifndef __pa_symbol
 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 #endif
-- 
2.20.1

[PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Christoph Hellwig]

From: Andrey Konovalov <andreyknvl@google.com>

To allow arm64 syscalls to accept tagged pointers from userspace, we must
untag them when they are passed to the kernel. Since untagging is done in
generic parts of the kernel, the untagged_addr macro needs to be defined
for all architectures.

Define it as a noop for architectures other than arm64.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e8834ac32b7..949d43e9c0b6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 
+#ifndef untagged_addr
+#define untagged_addr(addr) (addr)
+#endif
+
 #ifndef __pa_symbol
 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 #endif
-- 
2.20.1

[PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Christoph Hellwig]

From: Andrey Konovalov <andreyknvl@google.com>

To allow arm64 syscalls to accept tagged pointers from userspace, we must
untag them when they are passed to the kernel. Since untagging is done in
generic parts of the kernel, the untagged_addr macro needs to be defined
for all architectures.

Define it as a noop for architectures other than arm64.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e8834ac32b7..949d43e9c0b6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 
+#ifndef untagged_addr
+#define untagged_addr(addr) (addr)
+#endif
+
 #ifndef __pa_symbol
 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 #endif
-- 
2.20.1

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Khalid Aziz]

On 6/1/19 1:49 AM, Christoph Hellwig wrote:
> From: Andrey Konovalov <andreyknvl@google.com>
> 
> To allow arm64 syscalls to accept tagged pointers from userspace, we must
> untag them when they are passed to the kernel. Since untagging is done in
> generic parts of the kernel, the untagged_addr macro needs to be defined
> for all architectures.
> 
> Define it as a noop for architectures other than arm64.

Could you reword above sentence? We are already starting off with
untagged_addr() not being no-op for arm64 and sparc64. It will expand
further potentially. So something more along the lines of "Define it as
noop for architectures that do not support memory tagging". The first
paragraph in the log can also be rewritten to be not specific to arm64.

--
Khalid

> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/linux/mm.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834ac32b7..949d43e9c0b6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
>  #include <asm/pgtable.h>
>  #include <asm/processor.h>
>  
> +#ifndef untagged_addr
> +#define untagged_addr(addr) (addr)
> +#endif
> +
>  #ifndef __pa_symbol
>  #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
>  #endif
> 

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Khalid Aziz]

On 6/1/19 1:49 AM, Christoph Hellwig wrote:
> From: Andrey Konovalov <andreyknvl@google.com>
> 
> To allow arm64 syscalls to accept tagged pointers from userspace, we must
> untag them when they are passed to the kernel. Since untagging is done in
> generic parts of the kernel, the untagged_addr macro needs to be defined
> for all architectures.
> 
> Define it as a noop for architectures other than arm64.

Could you reword above sentence? We are already starting off with
untagged_addr() not being no-op for arm64 and sparc64. It will expand
further potentially. So something more along the lines of "Define it as
noop for architectures that do not support memory tagging". The first
paragraph in the log can also be rewritten to be not specific to arm64.

--
Khalid

> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/linux/mm.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834ac32b7..949d43e9c0b6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
>  #include <asm/pgtable.h>
>  #include <asm/processor.h>
>  
> +#ifndef untagged_addr
> +#define untagged_addr(addr) (addr)
> +#endif
> +
>  #ifndef __pa_symbol
>  #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
>  #endif
> 

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Khalid Aziz]

On 6/1/19 1:49 AM, Christoph Hellwig wrote:
> From: Andrey Konovalov <andreyknvl@google.com>
> 
> To allow arm64 syscalls to accept tagged pointers from userspace, we must
> untag them when they are passed to the kernel. Since untagging is done in
> generic parts of the kernel, the untagged_addr macro needs to be defined
> for all architectures.
> 
> Define it as a noop for architectures other than arm64.

Could you reword above sentence? We are already starting off with
untagged_addr() not being no-op for arm64 and sparc64. It will expand
further potentially. So something more along the lines of "Define it as
noop for architectures that do not support memory tagging". The first
paragraph in the log can also be rewritten to be not specific to arm64.

--
Khalid

> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/linux/mm.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834ac32b7..949d43e9c0b6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
>  #include <asm/pgtable.h>
>  #include <asm/processor.h>
>  
> +#ifndef untagged_addr
> +#define untagged_addr(addr) (addr)
> +#endif
> +
>  #ifndef __pa_symbol
>  #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
>  #endif
> 

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Christoph Hellwig]

On Mon, Jun 03, 2019 at 09:16:08AM -0600, Khalid Aziz wrote:
> Could you reword above sentence? We are already starting off with
> untagged_addr() not being no-op for arm64 and sparc64. It will expand
> further potentially. So something more along the lines of "Define it as
> noop for architectures that do not support memory tagging". The first
> paragraph in the log can also be rewritten to be not specific to arm64.

Well, as of this patch this actually is a no-op for everyone.

Linus, what do you think of applying this patch (maybe with a slightly
fixed up commit log) to 5.2-rc so that we remove a cross dependency
between the series?

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Christoph Hellwig]

On Mon, Jun 03, 2019 at 09:16:08AM -0600, Khalid Aziz wrote:
> Could you reword above sentence? We are already starting off with
> untagged_addr() not being no-op for arm64 and sparc64. It will expand
> further potentially. So something more along the lines of "Define it as
> noop for architectures that do not support memory tagging". The first
> paragraph in the log can also be rewritten to be not specific to arm64.

Well, as of this patch this actually is a no-op for everyone.

Linus, what do you think of applying this patch (maybe with a slightly
fixed up commit log) to 5.2-rc so that we remove a cross dependency
between the series?

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Christoph Hellwig]

On Mon, Jun 03, 2019 at 09:16:08AM -0600, Khalid Aziz wrote:
> Could you reword above sentence? We are already starting off with
> untagged_addr() not being no-op for arm64 and sparc64. It will expand
> further potentially. So something more along the lines of "Define it as
> noop for architectures that do not support memory tagging". The first
> paragraph in the log can also be rewritten to be not specific to arm64.

Well, as of this patch this actually is a no-op for everyone.

Linus, what do you think of applying this patch (maybe with a slightly
fixed up commit log) to 5.2-rc so that we remove a cross dependency
between the series?

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Andrey Konovalov]

On Tue, Jun 4, 2019 at 9:27 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Jun 03, 2019 at 09:16:08AM -0600, Khalid Aziz wrote:
> > Could you reword above sentence? We are already starting off with
> > untagged_addr() not being no-op for arm64 and sparc64. It will expand
> > further potentially. So something more along the lines of "Define it as
> > noop for architectures that do not support memory tagging". The first
> > paragraph in the log can also be rewritten to be not specific to arm64.
>
> Well, as of this patch this actually is a no-op for everyone.
>
> Linus, what do you think of applying this patch (maybe with a slightly
> fixed up commit log) to 5.2-rc so that we remove a cross dependency
> between the series?

(I have adjusted the patch description and have just sent it out
separately from the series).

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Andrey Konovalov]

On Tue, Jun 4, 2019 at 9:27 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Jun 03, 2019 at 09:16:08AM -0600, Khalid Aziz wrote:
> > Could you reword above sentence? We are already starting off with
> > untagged_addr() not being no-op for arm64 and sparc64. It will expand
> > further potentially. So something more along the lines of "Define it as
> > noop for architectures that do not support memory tagging". The first
> > paragraph in the log can also be rewritten to be not specific to arm64.
>
> Well, as of this patch this actually is a no-op for everyone.
>
> Linus, what do you think of applying this patch (maybe with a slightly
> fixed up commit log) to 5.2-rc so that we remove a cross dependency
> between the series?

(I have adjusted the patch description and have just sent it out
separately from the series).

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Andrey Konovalov]

On Tue, Jun 4, 2019 at 9:27 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Jun 03, 2019 at 09:16:08AM -0600, Khalid Aziz wrote:
> > Could you reword above sentence? We are already starting off with
> > untagged_addr() not being no-op for arm64 and sparc64. It will expand
> > further potentially. So something more along the lines of "Define it as
> > noop for architectures that do not support memory tagging". The first
> > paragraph in the log can also be rewritten to be not specific to arm64.
>
> Well, as of this patch this actually is a no-op for everyone.
>
> Linus, what do you think of applying this patch (maybe with a slightly
> fixed up commit log) to 5.2-rc so that we remove a cross dependency
> between the series?

(I have adjusted the patch description and have just sent it out
separately from the series).

Re: [PATCH 01/16] uaccess: add untagged_addr definition for other arches

[Andrey Konovalov]

On Tue, Jun 4, 2019 at 9:27 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Jun 03, 2019 at 09:16:08AM -0600, Khalid Aziz wrote:
> > Could you reword above sentence? We are already starting off with
> > untagged_addr() not being no-op for arm64 and sparc64. It will expand
> > further potentially. So something more along the lines of "Define it as
> > noop for architectures that do not support memory tagging". The first
> > paragraph in the log can also be rewritten to be not specific to arm64.
>
> Well, as of this patch this actually is a no-op for everyone.
>
> Linus, what do you think of applying this patch (maybe with a slightly
> fixed up commit log) to 5.2-rc so that we remove a cross dependency
> between the series?

(I have adjusted the patch description and have just sent it out
separately from the series).

[PATCH 02/16] mm: use untagged_addr() for get_user_pages_fast addresses

[Christoph Hellwig]

This will allow sparc64 to override its ADI tags for
get_user_pages and get_user_pages_fast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index f173fcbaf1b2..9775f7675653 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2145,7 +2145,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	unsigned long flags;
 	int nr = 0;
 
-	start &= PAGE_MASK;
+	start = untagged_addr(start) & PAGE_MASK;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
@@ -2218,7 +2218,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
-	start &= PAGE_MASK;
+	start = untagged_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
-- 
2.20.1

[PATCH 02/16] mm: use untagged_addr() for get_user_pages_fast addresses

[Christoph Hellwig]

This will allow sparc64 to override its ADI tags for
get_user_pages and get_user_pages_fast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index f173fcbaf1b2..9775f7675653 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2145,7 +2145,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	unsigned long flags;
 	int nr = 0;
 
-	start &= PAGE_MASK;
+	start = untagged_addr(start) & PAGE_MASK;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
@@ -2218,7 +2218,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
-	start &= PAGE_MASK;
+	start = untagged_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
-- 
2.20.1

[PATCH 02/16] mm: use untagged_addr() for get_user_pages_fast addresses

[Christoph Hellwig]

This will allow sparc64 to override its ADI tags for
get_user_pages and get_user_pages_fast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index f173fcbaf1b2..9775f7675653 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2145,7 +2145,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	unsigned long flags;
 	int nr = 0;
 
-	start &= PAGE_MASK;
+	start = untagged_addr(start) & PAGE_MASK;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
@@ -2218,7 +2218,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
-	start &= PAGE_MASK;
+	start = untagged_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
-- 
2.20.1

[PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

Pass in the already calculated end value instead of recomputing it, and
leave the end > start check in the callers instead of duplicating them
in the arch code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/s390/include/asm/pgtable.h   |  8 +-------
 arch/x86/include/asm/pgtable_64.h |  8 +-------
 mm/gup.c                          | 17 +++++++----------
 3 files changed, 9 insertions(+), 24 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 9f0195d5fa16..9b274fcaacb6 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1270,14 +1270,8 @@ static inline pte_t *pte_offset(pmd_t *pmd, unsigned long address)
 #define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
 #define pte_unmap(pte) do { } while (0)
 
-static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+static inline bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (end < start)
-		return false;
 	return end <= current->mm->context.asce_limit;
 }
 #define gup_fast_permitted gup_fast_permitted
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 0bb566315621..4990d26dfc73 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -259,14 +259,8 @@ extern void init_extra_mapping_uc(unsigned long phys, unsigned long size);
 extern void init_extra_mapping_wb(unsigned long phys, unsigned long size);
 
 #define gup_fast_permitted gup_fast_permitted
-static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+static inline bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long)nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (end < start)
-		return false;
 	if (end >> __VIRTUAL_MASK_SHIFT)
 		return false;
 	return true;
diff --git a/mm/gup.c b/mm/gup.c
index 9775f7675653..e7566f5ff9cf 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2122,13 +2122,9 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
  * Check if it's allowed to use __get_user_pages_fast() for the range, or
  * we need to fall back to the slow version:
  */
-bool gup_fast_permitted(unsigned long start, int nr_pages)
+static bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	return end >= start;
+	return true;
 }
 #endif
 
@@ -2149,6 +2145,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
+	if (end < start)
+		return 0;
 	if (unlikely(!access_ok((void __user *)start, len)))
 		return 0;
 
@@ -2164,7 +2162,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	 * block IPIs that come from THPs splitting.
 	 */
 
-	if (gup_fast_permitted(start, nr_pages)) {
+	if (gup_fast_permitted(start, end)) {
 		local_irq_save(flags);
 		gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
 		local_irq_restore(flags);
@@ -2223,13 +2221,12 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
-	if (nr_pages <= 0)
+	if (end < start)
 		return 0;
-
 	if (unlikely(!access_ok((void __user *)start, len)))
 		return -EFAULT;
 
-	if (gup_fast_permitted(start, nr_pages)) {
+	if (gup_fast_permitted(start, end)) {
 		local_irq_disable();
 		gup_pgd_range(addr, end, gup_flags, pages, &nr);
 		local_irq_enable();
-- 
2.20.1

[PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

Pass in the already calculated end value instead of recomputing it, and
leave the end > start check in the callers instead of duplicating them
in the arch code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/s390/include/asm/pgtable.h   |  8 +-------
 arch/x86/include/asm/pgtable_64.h |  8 +-------
 mm/gup.c                          | 17 +++++++----------
 3 files changed, 9 insertions(+), 24 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 9f0195d5fa16..9b274fcaacb6 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1270,14 +1270,8 @@ static inline pte_t *pte_offset(pmd_t *pmd, unsigned long address)
 #define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
 #define pte_unmap(pte) do { } while (0)
 
-static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+static inline bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (end < start)
-		return false;
 	return end <= current->mm->context.asce_limit;
 }
 #define gup_fast_permitted gup_fast_permitted
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 0bb566315621..4990d26dfc73 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -259,14 +259,8 @@ extern void init_extra_mapping_uc(unsigned long phys, unsigned long size);
 extern void init_extra_mapping_wb(unsigned long phys, unsigned long size);
 
 #define gup_fast_permitted gup_fast_permitted
-static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+static inline bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long)nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (end < start)
-		return false;
 	if (end >> __VIRTUAL_MASK_SHIFT)
 		return false;
 	return true;
diff --git a/mm/gup.c b/mm/gup.c
index 9775f7675653..e7566f5ff9cf 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2122,13 +2122,9 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
  * Check if it's allowed to use __get_user_pages_fast() for the range, or
  * we need to fall back to the slow version:
  */
-bool gup_fast_permitted(unsigned long start, int nr_pages)
+static bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	return end >= start;
+	return true;
 }
 #endif
 
@@ -2149,6 +2145,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
+	if (end < start)
+		return 0;
 	if (unlikely(!access_ok((void __user *)start, len)))
 		return 0;
 
@@ -2164,7 +2162,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	 * block IPIs that come from THPs splitting.
 	 */
 
-	if (gup_fast_permitted(start, nr_pages)) {
+	if (gup_fast_permitted(start, end)) {
 		local_irq_save(flags);
 		gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
 		local_irq_restore(flags);
@@ -2223,13 +2221,12 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
-	if (nr_pages <= 0)
+	if (end < start)
 		return 0;
-
 	if (unlikely(!access_ok((void __user *)start, len)))
 		return -EFAULT;
 
-	if (gup_fast_permitted(start, nr_pages)) {
+	if (gup_fast_permitted(start, end)) {
 		local_irq_disable();
 		gup_pgd_range(addr, end, gup_flags, pages, &nr);
 		local_irq_enable();
-- 
2.20.1

[PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

Pass in the already calculated end value instead of recomputing it, and
leave the end > start check in the callers instead of duplicating them
in the arch code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/s390/include/asm/pgtable.h   |  8 +-------
 arch/x86/include/asm/pgtable_64.h |  8 +-------
 mm/gup.c                          | 17 +++++++----------
 3 files changed, 9 insertions(+), 24 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 9f0195d5fa16..9b274fcaacb6 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1270,14 +1270,8 @@ static inline pte_t *pte_offset(pmd_t *pmd, unsigned long address)
 #define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
 #define pte_unmap(pte) do { } while (0)
 
-static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+static inline bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (end < start)
-		return false;
 	return end <= current->mm->context.asce_limit;
 }
 #define gup_fast_permitted gup_fast_permitted
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 0bb566315621..4990d26dfc73 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -259,14 +259,8 @@ extern void init_extra_mapping_uc(unsigned long phys, unsigned long size);
 extern void init_extra_mapping_wb(unsigned long phys, unsigned long size);
 
 #define gup_fast_permitted gup_fast_permitted
-static inline bool gup_fast_permitted(unsigned long start, int nr_pages)
+static inline bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long)nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (end < start)
-		return false;
 	if (end >> __VIRTUAL_MASK_SHIFT)
 		return false;
 	return true;
diff --git a/mm/gup.c b/mm/gup.c
index 9775f7675653..e7566f5ff9cf 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2122,13 +2122,9 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
  * Check if it's allowed to use __get_user_pages_fast() for the range, or
  * we need to fall back to the slow version:
  */
-bool gup_fast_permitted(unsigned long start, int nr_pages)
+static bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	unsigned long len, end;
-
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	return end >= start;
+	return true;
 }
 #endif
 
@@ -2149,6 +2145,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
+	if (end < start)
+		return 0;
 	if (unlikely(!access_ok((void __user *)start, len)))
 		return 0;
 
@@ -2164,7 +2162,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	 * block IPIs that come from THPs splitting.
 	 */
 
-	if (gup_fast_permitted(start, nr_pages)) {
+	if (gup_fast_permitted(start, end)) {
 		local_irq_save(flags);
 		gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
 		local_irq_restore(flags);
@@ -2223,13 +2221,12 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
 
-	if (nr_pages <= 0)
+	if (end < start)
 		return 0;
-
 	if (unlikely(!access_ok((void __user *)start, len)))
 		return -EFAULT;
 
-	if (gup_fast_permitted(start, nr_pages)) {
+	if (gup_fast_permitted(start, end)) {
 		local_irq_disable();
 		gup_pgd_range(addr, end, gup_flags, pages, &nr);
 		local_irq_enable();
-- 
2.20.1

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Pass in the already calculated end value instead of recomputing it, and
> leave the end > start check in the callers instead of duplicating them
> in the arch code.

Good cleanup, except it's wrong.

> -       if (nr_pages <= 0)
> +       if (end < start)
>                 return 0;

You moved the overflow test to generic code - good.

You removed the sign and zero test on nr_pages - bad.

The zero test in particular is _important_ - the GUP range operators
know and depend on the fact that they are passed a non-empty range.

The sign test it less so, but is definitely appropriate. It might be
even better to check that the "<< PAGE_SHIFT" doesn't overflow in
"long", of course, but with callers being supposed to be trusted, the
sign test at least checks for stupid underflow issues.

So at the very least that "(end < start)" needs to be "(end <start)", but honestly, I think the sign of the nr_pages should be
continued to be checked.

                      Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Pass in the already calculated end value instead of recomputing it, and
> leave the end > start check in the callers instead of duplicating them
> in the arch code.

Good cleanup, except it's wrong.

> -       if (nr_pages <= 0)
> +       if (end < start)
>                 return 0;

You moved the overflow test to generic code - good.

You removed the sign and zero test on nr_pages - bad.

The zero test in particular is _important_ - the GUP range operators
know and depend on the fact that they are passed a non-empty range.

The sign test it less so, but is definitely appropriate. It might be
even better to check that the "<< PAGE_SHIFT" doesn't overflow in
"long", of course, but with callers being supposed to be trusted, the
sign test at least checks for stupid underflow issues.

So at the very least that "(end < start)" needs to be "(end <=
start)", but honestly, I think the sign of the nr_pages should be
continued to be checked.

                      Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Pass in the already calculated end value instead of recomputing it, and
> leave the end > start check in the callers instead of duplicating them
> in the arch code.

Good cleanup, except it's wrong.

> -       if (nr_pages <= 0)
> +       if (end < start)
>                 return 0;

You moved the overflow test to generic code - good.

You removed the sign and zero test on nr_pages - bad.

The zero test in particular is _important_ - the GUP range operators
know and depend on the fact that they are passed a non-empty range.

The sign test it less so, but is definitely appropriate. It might be
even better to check that the "<< PAGE_SHIFT" doesn't overflow in
"long", of course, but with callers being supposed to be trusted, the
sign test at least checks for stupid underflow issues.

So at the very least that "(end < start)" needs to be "(end <=
start)", but honestly, I think the sign of the nr_pages should be
continued to be checked.

                      Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Pass in the already calculated end value instead of recomputing it, and
> leave the end > start check in the callers instead of duplicating them
> in the arch code.

Good cleanup, except it's wrong.

> -       if (nr_pages <= 0)
> +       if (end < start)
>                 return 0;

You moved the overflow test to generic code - good.

You removed the sign and zero test on nr_pages - bad.

The zero test in particular is _important_ - the GUP range operators
know and depend on the fact that they are passed a non-empty range.

The sign test it less so, but is definitely appropriate. It might be
even better to check that the "<< PAGE_SHIFT" doesn't overflow in
"long", of course, but with callers being supposed to be trusted, the
sign test at least checks for stupid underflow issues.

So at the very least that "(end < start)" needs to be "(end <=
start)", but honestly, I think the sign of the nr_pages should be
continued to be checked.

                      Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

On Sat, Jun 01, 2019 at 09:14:17AM -0700, Linus Torvalds wrote:
> On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > Pass in the already calculated end value instead of recomputing it, and
> > leave the end > start check in the callers instead of duplicating them
> > in the arch code.
> 
> Good cleanup, except it's wrong.
> 
> > -       if (nr_pages <= 0)
> > +       if (end < start)
> >                 return 0;
> 
> You moved the overflow test to generic code - good.
> 
> You removed the sign and zero test on nr_pages - bad.

I only removed a duplicate of it.  The full (old) code in
get_user_pages_fast() looks like this:

	if (nr_pages <= 0)
		return 0;

	if (unlikely(!access_ok((void __user *)start, len)))
		return -EFAULT;

	if (gup_fast_permitted(start, nr_pages)) {

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

On Sat, Jun 01, 2019 at 09:14:17AM -0700, Linus Torvalds wrote:
> On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > Pass in the already calculated end value instead of recomputing it, and
> > leave the end > start check in the callers instead of duplicating them
> > in the arch code.
> 
> Good cleanup, except it's wrong.
> 
> > -       if (nr_pages <= 0)
> > +       if (end < start)
> >                 return 0;
> 
> You moved the overflow test to generic code - good.
> 
> You removed the sign and zero test on nr_pages - bad.

I only removed a duplicate of it.  The full (old) code in
get_user_pages_fast() looks like this:

	if (nr_pages <= 0)
		return 0;

	if (unlikely(!access_ok((void __user *)start, len)))
		return -EFAULT;

	if (gup_fast_permitted(start, nr_pages)) {

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

On Sat, Jun 01, 2019 at 09:14:17AM -0700, Linus Torvalds wrote:
> On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > Pass in the already calculated end value instead of recomputing it, and
> > leave the end > start check in the callers instead of duplicating them
> > in the arch code.
> 
> Good cleanup, except it's wrong.
> 
> > -       if (nr_pages <= 0)
> > +       if (end < start)
> >                 return 0;
> 
> You moved the overflow test to generic code - good.
> 
> You removed the sign and zero test on nr_pages - bad.

I only removed a duplicate of it.  The full (old) code in
get_user_pages_fast() looks like this:

	if (nr_pages <= 0)
		return 0;

	if (unlikely(!access_ok((void __user *)start, len)))
		return -EFAULT;

	if (gup_fast_permitted(start, nr_pages)) {

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 12:41 AM Christoph Hellwig <hch@lst.de> wrote:
>
> I only removed a duplicate of it.

I don't see any remaining cases.

> The full (old) code in get_user_pages_fast() looks like this:
>
>         if (nr_pages <= 0)
>                 return 0;
>
>         if (unlikely(!access_ok((void __user *)start, len)))
>                 return -EFAULT;
>
>         if (gup_fast_permitted(start, nr_pages)) {

Yes, and that code was correct.

The new code has no test at all for "nr_pages = 0", afaik.

                 Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 12:41 AM Christoph Hellwig <hch@lst.de> wrote:
>
> I only removed a duplicate of it.

I don't see any remaining cases.

> The full (old) code in get_user_pages_fast() looks like this:
>
>         if (nr_pages <= 0)
>                 return 0;
>
>         if (unlikely(!access_ok((void __user *)start, len)))
>                 return -EFAULT;
>
>         if (gup_fast_permitted(start, nr_pages)) {

Yes, and that code was correct.

The new code has no test at all for "nr_pages == 0", afaik.

                 Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 12:41 AM Christoph Hellwig <hch@lst.de> wrote:
>
> I only removed a duplicate of it.

I don't see any remaining cases.

> The full (old) code in get_user_pages_fast() looks like this:
>
>         if (nr_pages <= 0)
>                 return 0;
>
>         if (unlikely(!access_ok((void __user *)start, len)))
>                 return -EFAULT;
>
>         if (gup_fast_permitted(start, nr_pages)) {

Yes, and that code was correct.

The new code has no test at all for "nr_pages == 0", afaik.

                 Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 12:41 AM Christoph Hellwig <hch@lst.de> wrote:
>
> I only removed a duplicate of it.

I don't see any remaining cases.

> The full (old) code in get_user_pages_fast() looks like this:
>
>         if (nr_pages <= 0)
>                 return 0;
>
>         if (unlikely(!access_ok((void __user *)start, len)))
>                 return -EFAULT;
>
>         if (gup_fast_permitted(start, nr_pages)) {

Yes, and that code was correct.

The new code has no test at all for "nr_pages == 0", afaik.

                 Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 9:08 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> The new code has no test at all for "nr_pages = 0", afaik.

Note that it really is important to check for that, because right now we do

        if (gup_fast_permitted(start, nr_pages)) {
                local_irq_save(flags);
                gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
                local_irq_restore(flags);
        }

and that gup_pgd_range() function *depends* on the range being
non-zero, and does

        pgdp = pgd_offset(current->mm, addr);
        do {
                pgd_t pgd = READ_ONCE(*pgdp);
...
        } while (pgdp++, addr = next, addr != end);

Note how a zero range would turn into an infinite range here.

And the only check for 0 was that

        if (nr_pages <= 0)
                return 0;

in get_user_pages_fast() that you removed.

(Admittedly, it would be much better to have that check in
__get_user_pages_fast() itself, because we do have callers that call
the double-underscore version)

Now, I sincerely hope that we don't have anybody that passes in a zero
nr_pages (or a negative one), but we do actually have a comment saying
it's ok.

Note that the check for "if (end < start)" not only does not check for
0, it also doesn't really check for negative. It checks for
_overflow_. Admittedly most negative values would be expected to
overflow, but it's still a very different issue.

Maybe you added the check for negative somewhere else (in another
patch), but I don't see it.

                Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 9:08 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> The new code has no test at all for "nr_pages == 0", afaik.

Note that it really is important to check for that, because right now we do

        if (gup_fast_permitted(start, nr_pages)) {
                local_irq_save(flags);
                gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
                local_irq_restore(flags);
        }

and that gup_pgd_range() function *depends* on the range being
non-zero, and does

        pgdp = pgd_offset(current->mm, addr);
        do {
                pgd_t pgd = READ_ONCE(*pgdp);
...
        } while (pgdp++, addr = next, addr != end);

Note how a zero range would turn into an infinite range here.

And the only check for 0 was that

        if (nr_pages <= 0)
                return 0;

in get_user_pages_fast() that you removed.

(Admittedly, it would be much better to have that check in
__get_user_pages_fast() itself, because we do have callers that call
the double-underscore version)

Now, I sincerely hope that we don't have anybody that passes in a zero
nr_pages (or a negative one), but we do actually have a comment saying
it's ok.

Note that the check for "if (end < start)" not only does not check for
0, it also doesn't really check for negative. It checks for
_overflow_. Admittedly most negative values would be expected to
overflow, but it's still a very different issue.

Maybe you added the check for negative somewhere else (in another
patch), but I don't see it.

                Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 9:08 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> The new code has no test at all for "nr_pages == 0", afaik.

Note that it really is important to check for that, because right now we do

        if (gup_fast_permitted(start, nr_pages)) {
                local_irq_save(flags);
                gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
                local_irq_restore(flags);
        }

and that gup_pgd_range() function *depends* on the range being
non-zero, and does

        pgdp = pgd_offset(current->mm, addr);
        do {
                pgd_t pgd = READ_ONCE(*pgdp);
...
        } while (pgdp++, addr = next, addr != end);

Note how a zero range would turn into an infinite range here.

And the only check for 0 was that

        if (nr_pages <= 0)
                return 0;

in get_user_pages_fast() that you removed.

(Admittedly, it would be much better to have that check in
__get_user_pages_fast() itself, because we do have callers that call
the double-underscore version)

Now, I sincerely hope that we don't have anybody that passes in a zero
nr_pages (or a negative one), but we do actually have a comment saying
it's ok.

Note that the check for "if (end < start)" not only does not check for
0, it also doesn't really check for negative. It checks for
_overflow_. Admittedly most negative values would be expected to
overflow, but it's still a very different issue.

Maybe you added the check for negative somewhere else (in another
patch), but I don't see it.

                Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Linus Torvalds]

On Mon, Jun 3, 2019 at 9:08 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> The new code has no test at all for "nr_pages == 0", afaik.

Note that it really is important to check for that, because right now we do

        if (gup_fast_permitted(start, nr_pages)) {
                local_irq_save(flags);
                gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
                local_irq_restore(flags);
        }

and that gup_pgd_range() function *depends* on the range being
non-zero, and does

        pgdp = pgd_offset(current->mm, addr);
        do {
                pgd_t pgd = READ_ONCE(*pgdp);
...
        } while (pgdp++, addr = next, addr != end);

Note how a zero range would turn into an infinite range here.

And the only check for 0 was that

        if (nr_pages <= 0)
                return 0;

in get_user_pages_fast() that you removed.

(Admittedly, it would be much better to have that check in
__get_user_pages_fast() itself, because we do have callers that call
the double-underscore version)

Now, I sincerely hope that we don't have anybody that passes in a zero
nr_pages (or a negative one), but we do actually have a comment saying
it's ok.

Note that the check for "if (end < start)" not only does not check for
0, it also doesn't really check for negative. It checks for
_overflow_. Admittedly most negative values would be expected to
overflow, but it's still a very different issue.

Maybe you added the check for negative somewhere else (in another
patch), but I don't see it.

                Linus

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

On Mon, Jun 03, 2019 at 10:02:10AM -0700, Linus Torvalds wrote:
> On Mon, Jun 3, 2019 at 9:08 AM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > The new code has no test at all for "nr_pages = 0", afaik.
> 
> Note that it really is important to check for that, because right now we do

True.  The 0 check got lost.  I'll make sure we do the right thing for
the next version.

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

On Mon, Jun 03, 2019 at 10:02:10AM -0700, Linus Torvalds wrote:
> On Mon, Jun 3, 2019 at 9:08 AM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > The new code has no test at all for "nr_pages == 0", afaik.
> 
> Note that it really is important to check for that, because right now we do

True.  The 0 check got lost.  I'll make sure we do the right thing for
the next version.

Re: [PATCH 03/16] mm: simplify gup_fast_permitted

[Christoph Hellwig]

On Mon, Jun 03, 2019 at 10:02:10AM -0700, Linus Torvalds wrote:
> On Mon, Jun 3, 2019 at 9:08 AM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > The new code has no test at all for "nr_pages == 0", afaik.
> 
> Note that it really is important to check for that, because right now we do

True.  The 0 check got lost.  I'll make sure we do the right thing for
the next version.

[PATCH 04/16] mm: lift the x86_32 PAE version of gup_get_pte to common code

[Christoph Hellwig]

The split low/high access is the only non-READ_ONCE version of
gup_get_pte that did show up in the various arch implemenations.
Lift it to common code and drop the ifdef based arch override.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/Kconfig                      |  1 +
 arch/x86/include/asm/pgtable-3level.h | 47 ------------------------
 arch/x86/kvm/mmu.c                    |  2 +-
 mm/Kconfig                            |  3 ++
 mm/gup.c                              | 51 ++++++++++++++++++++++++---
 5 files changed, 52 insertions(+), 52 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2bbbd4d1ba31..7cd53cc59f0f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -121,6 +121,7 @@ config X86
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select GENERIC_TIME_VSYSCALL
+	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
 	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
 	select HAVE_ACPI_APEI			if ACPI
 	select HAVE_ACPI_APEI_NMI		if ACPI
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index f8b1ad2c3828..e3633795fb22 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -285,53 +285,6 @@ static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
 #define __pte_to_swp_entry(pte)	(__swp_entry(__pteval_swp_type(pte), \
 					     __pteval_swp_offset(pte)))
 
-#define gup_get_pte gup_get_pte
-/*
- * WARNING: only to be used in the get_user_pages_fast() implementation.
- *
- * With get_user_pages_fast(), we walk down the pagetables without taking
- * any locks.  For this we would like to load the pointers atomically,
- * but that is not possible (without expensive cmpxchg8b) on PAE.  What
- * we do have is the guarantee that a PTE will only either go from not
- * present to present, or present to not present or both -- it will not
- * switch to a completely different present page without a TLB flush in
- * between; something that we are blocking by holding interrupts off.
- *
- * Setting ptes from not present to present goes:
- *
- *   ptep->pte_high = h;
- *   smp_wmb();
- *   ptep->pte_low = l;
- *
- * And present to not present goes:
- *
- *   ptep->pte_low = 0;
- *   smp_wmb();
- *   ptep->pte_high = 0;
- *
- * We must ensure here that the load of pte_low sees 'l' iff pte_high
- * sees 'h'. We load pte_high *after* loading pte_low, which ensures we
- * don't see an older value of pte_high.  *Then* we recheck pte_low,
- * which ensures that we haven't picked up a changed pte high. We might
- * have gotten rubbish values from pte_low and pte_high, but we are
- * guaranteed that pte_low will not have the present bit set *unless*
- * it is 'l'. Because get_user_pages_fast() only operates on present ptes
- * we're safe.
- */
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-	pte_t pte;
-
-	do {
-		pte.pte_low = ptep->pte_low;
-		smp_rmb();
-		pte.pte_high = ptep->pte_high;
-		smp_rmb();
-	} while (unlikely(pte.pte_low != ptep->pte_low));
-
-	return pte;
-}
-
 #include <asm/pgtable-invert.h>
 
 #endif /* _ASM_X86_PGTABLE_3LEVEL_H */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1e9ba81accba..3f7cd11168f9 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -653,7 +653,7 @@ static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
 
 /*
  * The idea using the light way get the spte on x86_32 guest is from
- * gup_get_pte(arch/x86/mm/gup.c).
+ * gup_get_pte (mm/gup.c).
  *
  * An spte tlb flush may be pending, because kvm_set_pte_rmapp
  * coalesces them and we are running out of the MMU lock.  Therefore
diff --git a/mm/Kconfig b/mm/Kconfig
index f0c76ba47695..fe51f104a9e0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -762,6 +762,9 @@ config GUP_BENCHMARK
 
 	  See tools/testing/selftests/vm/gup_benchmark.c
 
+config GUP_GET_PTE_LOW_HIGH
+	bool
+
 config ARCH_HAS_PTE_SPECIAL
 	bool
 
diff --git a/mm/gup.c b/mm/gup.c
index e7566f5ff9cf..a86d65cd7051 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1683,17 +1683,60 @@ struct page *get_dump_page(unsigned long addr)
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
 #ifdef CONFIG_HAVE_GENERIC_GUP
+#ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
+/*
+ * WARNING: only to be used in the get_user_pages_fast() implementation.
+ *
+ * With get_user_pages_fast(), we walk down the pagetables without taking any
+ * locks.  For this we would like to load the pointers atomically, but sometimes
+ * that is not possible (e.g. without expensive cmpxchg8b on x86_32 PAE).  What
+ * we do have is the guarantee that a PTE will only either go from not present
+ * to present, or present to not present or both -- it will not switch to a
+ * completely different present page without a TLB flush in between; something
+ * that we are blocking by holding interrupts off.
+ *
+ * Setting ptes from not present to present goes:
+ *
+ *   ptep->pte_high = h;
+ *   smp_wmb();
+ *   ptep->pte_low = l;
+ *
+ * And present to not present goes:
+ *
+ *   ptep->pte_low = 0;
+ *   smp_wmb();
+ *   ptep->pte_high = 0;
+ *
+ * We must ensure here that the load of pte_low sees 'l' IFF pte_high sees 'h'.
+ * We load pte_high *after* loading pte_low, which ensures we don't see an older
+ * value of pte_high.  *Then* we recheck pte_low, which ensures that we haven't
+ * picked up a changed pte high. We might have gotten rubbish values from
+ * pte_low and pte_high, but we are guaranteed that pte_low will not have the
+ * present bit set *unless* it is 'l'. Because get_user_pages_fast() only
+ * operates on present ptes we're safe.
+ */
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	pte_t pte;
 
-#ifndef gup_get_pte
+	do {
+		pte.pte_low = ptep->pte_low;
+		smp_rmb();
+		pte.pte_high = ptep->pte_high;
+		smp_rmb();
+	} while (unlikely(pte.pte_low != ptep->pte_low));
+
+	return pte;
+}
+#else /* CONFIG_GUP_GET_PTE_LOW_HIGH */
 /*
- * We assume that the PTE can be read atomically. If this is not the case for
- * your architecture, please provide the helper.
+ * We require that the PTE can be read atomically.
  */
 static inline pte_t gup_get_pte(pte_t *ptep)
 {
 	return READ_ONCE(*ptep);
 }
-#endif
+#endif /* CONFIG_GUP_GET_PTE_LOW_HIGH */
 
 static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)
 {
-- 
2.20.1

[PATCH 04/16] mm: lift the x86_32 PAE version of gup_get_pte to common code

[Christoph Hellwig]

The split low/high access is the only non-READ_ONCE version of
gup_get_pte that did show up in the various arch implemenations.
Lift it to common code and drop the ifdef based arch override.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/Kconfig                      |  1 +
 arch/x86/include/asm/pgtable-3level.h | 47 ------------------------
 arch/x86/kvm/mmu.c                    |  2 +-
 mm/Kconfig                            |  3 ++
 mm/gup.c                              | 51 ++++++++++++++++++++++++---
 5 files changed, 52 insertions(+), 52 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2bbbd4d1ba31..7cd53cc59f0f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -121,6 +121,7 @@ config X86
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select GENERIC_TIME_VSYSCALL
+	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
 	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
 	select HAVE_ACPI_APEI			if ACPI
 	select HAVE_ACPI_APEI_NMI		if ACPI
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index f8b1ad2c3828..e3633795fb22 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -285,53 +285,6 @@ static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
 #define __pte_to_swp_entry(pte)	(__swp_entry(__pteval_swp_type(pte), \
 					     __pteval_swp_offset(pte)))
 
-#define gup_get_pte gup_get_pte
-/*
- * WARNING: only to be used in the get_user_pages_fast() implementation.
- *
- * With get_user_pages_fast(), we walk down the pagetables without taking
- * any locks.  For this we would like to load the pointers atomically,
- * but that is not possible (without expensive cmpxchg8b) on PAE.  What
- * we do have is the guarantee that a PTE will only either go from not
- * present to present, or present to not present or both -- it will not
- * switch to a completely different present page without a TLB flush in
- * between; something that we are blocking by holding interrupts off.
- *
- * Setting ptes from not present to present goes:
- *
- *   ptep->pte_high = h;
- *   smp_wmb();
- *   ptep->pte_low = l;
- *
- * And present to not present goes:
- *
- *   ptep->pte_low = 0;
- *   smp_wmb();
- *   ptep->pte_high = 0;
- *
- * We must ensure here that the load of pte_low sees 'l' iff pte_high
- * sees 'h'. We load pte_high *after* loading pte_low, which ensures we
- * don't see an older value of pte_high.  *Then* we recheck pte_low,
- * which ensures that we haven't picked up a changed pte high. We might
- * have gotten rubbish values from pte_low and pte_high, but we are
- * guaranteed that pte_low will not have the present bit set *unless*
- * it is 'l'. Because get_user_pages_fast() only operates on present ptes
- * we're safe.
- */
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-	pte_t pte;
-
-	do {
-		pte.pte_low = ptep->pte_low;
-		smp_rmb();
-		pte.pte_high = ptep->pte_high;
-		smp_rmb();
-	} while (unlikely(pte.pte_low != ptep->pte_low));
-
-	return pte;
-}
-
 #include <asm/pgtable-invert.h>
 
 #endif /* _ASM_X86_PGTABLE_3LEVEL_H */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1e9ba81accba..3f7cd11168f9 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -653,7 +653,7 @@ static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
 
 /*
  * The idea using the light way get the spte on x86_32 guest is from
- * gup_get_pte(arch/x86/mm/gup.c).
+ * gup_get_pte (mm/gup.c).
  *
  * An spte tlb flush may be pending, because kvm_set_pte_rmapp
  * coalesces them and we are running out of the MMU lock.  Therefore
diff --git a/mm/Kconfig b/mm/Kconfig
index f0c76ba47695..fe51f104a9e0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -762,6 +762,9 @@ config GUP_BENCHMARK
 
 	  See tools/testing/selftests/vm/gup_benchmark.c
 
+config GUP_GET_PTE_LOW_HIGH
+	bool
+
 config ARCH_HAS_PTE_SPECIAL
 	bool
 
diff --git a/mm/gup.c b/mm/gup.c
index e7566f5ff9cf..a86d65cd7051 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1683,17 +1683,60 @@ struct page *get_dump_page(unsigned long addr)
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
 #ifdef CONFIG_HAVE_GENERIC_GUP
+#ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
+/*
+ * WARNING: only to be used in the get_user_pages_fast() implementation.
+ *
+ * With get_user_pages_fast(), we walk down the pagetables without taking any
+ * locks.  For this we would like to load the pointers atomically, but sometimes
+ * that is not possible (e.g. without expensive cmpxchg8b on x86_32 PAE).  What
+ * we do have is the guarantee that a PTE will only either go from not present
+ * to present, or present to not present or both -- it will not switch to a
+ * completely different present page without a TLB flush in between; something
+ * that we are blocking by holding interrupts off.
+ *
+ * Setting ptes from not present to present goes:
+ *
+ *   ptep->pte_high = h;
+ *   smp_wmb();
+ *   ptep->pte_low = l;
+ *
+ * And present to not present goes:
+ *
+ *   ptep->pte_low = 0;
+ *   smp_wmb();
+ *   ptep->pte_high = 0;
+ *
+ * We must ensure here that the load of pte_low sees 'l' IFF pte_high sees 'h'.
+ * We load pte_high *after* loading pte_low, which ensures we don't see an older
+ * value of pte_high.  *Then* we recheck pte_low, which ensures that we haven't
+ * picked up a changed pte high. We might have gotten rubbish values from
+ * pte_low and pte_high, but we are guaranteed that pte_low will not have the
+ * present bit set *unless* it is 'l'. Because get_user_pages_fast() only
+ * operates on present ptes we're safe.
+ */
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	pte_t pte;
 
-#ifndef gup_get_pte
+	do {
+		pte.pte_low = ptep->pte_low;
+		smp_rmb();
+		pte.pte_high = ptep->pte_high;
+		smp_rmb();
+	} while (unlikely(pte.pte_low != ptep->pte_low));
+
+	return pte;
+}
+#else /* CONFIG_GUP_GET_PTE_LOW_HIGH */
 /*
- * We assume that the PTE can be read atomically. If this is not the case for
- * your architecture, please provide the helper.
+ * We require that the PTE can be read atomically.
  */
 static inline pte_t gup_get_pte(pte_t *ptep)
 {
 	return READ_ONCE(*ptep);
 }
-#endif
+#endif /* CONFIG_GUP_GET_PTE_LOW_HIGH */
 
 static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)
 {
-- 
2.20.1

[PATCH 04/16] mm: lift the x86_32 PAE version of gup_get_pte to common code

[Christoph Hellwig]

The split low/high access is the only non-READ_ONCE version of
gup_get_pte that did show up in the various arch implemenations.
Lift it to common code and drop the ifdef based arch override.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/Kconfig                      |  1 +
 arch/x86/include/asm/pgtable-3level.h | 47 ------------------------
 arch/x86/kvm/mmu.c                    |  2 +-
 mm/Kconfig                            |  3 ++
 mm/gup.c                              | 51 ++++++++++++++++++++++++---
 5 files changed, 52 insertions(+), 52 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2bbbd4d1ba31..7cd53cc59f0f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -121,6 +121,7 @@ config X86
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select GENERIC_TIME_VSYSCALL
+	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
 	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
 	select HAVE_ACPI_APEI			if ACPI
 	select HAVE_ACPI_APEI_NMI		if ACPI
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index f8b1ad2c3828..e3633795fb22 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -285,53 +285,6 @@ static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
 #define __pte_to_swp_entry(pte)	(__swp_entry(__pteval_swp_type(pte), \
 					     __pteval_swp_offset(pte)))
 
-#define gup_get_pte gup_get_pte
-/*
- * WARNING: only to be used in the get_user_pages_fast() implementation.
- *
- * With get_user_pages_fast(), we walk down the pagetables without taking
- * any locks.  For this we would like to load the pointers atomically,
- * but that is not possible (without expensive cmpxchg8b) on PAE.  What
- * we do have is the guarantee that a PTE will only either go from not
- * present to present, or present to not present or both -- it will not
- * switch to a completely different present page without a TLB flush in
- * between; something that we are blocking by holding interrupts off.
- *
- * Setting ptes from not present to present goes:
- *
- *   ptep->pte_high = h;
- *   smp_wmb();
- *   ptep->pte_low = l;
- *
- * And present to not present goes:
- *
- *   ptep->pte_low = 0;
- *   smp_wmb();
- *   ptep->pte_high = 0;
- *
- * We must ensure here that the load of pte_low sees 'l' iff pte_high
- * sees 'h'. We load pte_high *after* loading pte_low, which ensures we
- * don't see an older value of pte_high.  *Then* we recheck pte_low,
- * which ensures that we haven't picked up a changed pte high. We might
- * have gotten rubbish values from pte_low and pte_high, but we are
- * guaranteed that pte_low will not have the present bit set *unless*
- * it is 'l'. Because get_user_pages_fast() only operates on present ptes
- * we're safe.
- */
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-	pte_t pte;
-
-	do {
-		pte.pte_low = ptep->pte_low;
-		smp_rmb();
-		pte.pte_high = ptep->pte_high;
-		smp_rmb();
-	} while (unlikely(pte.pte_low != ptep->pte_low));
-
-	return pte;
-}
-
 #include <asm/pgtable-invert.h>
 
 #endif /* _ASM_X86_PGTABLE_3LEVEL_H */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1e9ba81accba..3f7cd11168f9 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -653,7 +653,7 @@ static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
 
 /*
  * The idea using the light way get the spte on x86_32 guest is from
- * gup_get_pte(arch/x86/mm/gup.c).
+ * gup_get_pte (mm/gup.c).
  *
  * An spte tlb flush may be pending, because kvm_set_pte_rmapp
  * coalesces them and we are running out of the MMU lock.  Therefore
diff --git a/mm/Kconfig b/mm/Kconfig
index f0c76ba47695..fe51f104a9e0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -762,6 +762,9 @@ config GUP_BENCHMARK
 
 	  See tools/testing/selftests/vm/gup_benchmark.c
 
+config GUP_GET_PTE_LOW_HIGH
+	bool
+
 config ARCH_HAS_PTE_SPECIAL
 	bool
 
diff --git a/mm/gup.c b/mm/gup.c
index e7566f5ff9cf..a86d65cd7051 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1683,17 +1683,60 @@ struct page *get_dump_page(unsigned long addr)
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
 #ifdef CONFIG_HAVE_GENERIC_GUP
+#ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
+/*
+ * WARNING: only to be used in the get_user_pages_fast() implementation.
+ *
+ * With get_user_pages_fast(), we walk down the pagetables without taking any
+ * locks.  For this we would like to load the pointers atomically, but sometimes
+ * that is not possible (e.g. without expensive cmpxchg8b on x86_32 PAE).  What
+ * we do have is the guarantee that a PTE will only either go from not present
+ * to present, or present to not present or both -- it will not switch to a
+ * completely different present page without a TLB flush in between; something
+ * that we are blocking by holding interrupts off.
+ *
+ * Setting ptes from not present to present goes:
+ *
+ *   ptep->pte_high = h;
+ *   smp_wmb();
+ *   ptep->pte_low = l;
+ *
+ * And present to not present goes:
+ *
+ *   ptep->pte_low = 0;
+ *   smp_wmb();
+ *   ptep->pte_high = 0;
+ *
+ * We must ensure here that the load of pte_low sees 'l' IFF pte_high sees 'h'.
+ * We load pte_high *after* loading pte_low, which ensures we don't see an older
+ * value of pte_high.  *Then* we recheck pte_low, which ensures that we haven't
+ * picked up a changed pte high. We might have gotten rubbish values from
+ * pte_low and pte_high, but we are guaranteed that pte_low will not have the
+ * present bit set *unless* it is 'l'. Because get_user_pages_fast() only
+ * operates on present ptes we're safe.
+ */
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	pte_t pte;
 
-#ifndef gup_get_pte
+	do {
+		pte.pte_low = ptep->pte_low;
+		smp_rmb();
+		pte.pte_high = ptep->pte_high;
+		smp_rmb();
+	} while (unlikely(pte.pte_low != ptep->pte_low));
+
+	return pte;
+}
+#else /* CONFIG_GUP_GET_PTE_LOW_HIGH */
 /*
- * We assume that the PTE can be read atomically. If this is not the case for
- * your architecture, please provide the helper.
+ * We require that the PTE can be read atomically.
  */
 static inline pte_t gup_get_pte(pte_t *ptep)
 {
 	return READ_ONCE(*ptep);
 }
-#endif
+#endif /* CONFIG_GUP_GET_PTE_LOW_HIGH */
 
 static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)
 {
-- 
2.20.1

[PATCH 05/16] MIPS: use the generic get_user_pages_fast code

[Christoph Hellwig]

The mips code is mostly equivalent to the generic one, minus various
bugfixes and an arch override for gup_fast_permitted.

Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has
pte_special and pte_mkspecial implemented and used in the existing
gup code.  They are no-op stubs, though which makes me a little unsure
if this is really right thing to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/Kconfig               |   3 +
 arch/mips/include/asm/pgtable.h |   3 +
 arch/mips/mm/Makefile           |   1 -
 arch/mips/mm/gup.c              | 303 --------------------------------
 4 files changed, 6 insertions(+), 304 deletions(-)
 delete mode 100644 arch/mips/mm/gup.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 70d3200476bf..64108a2a16d4 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,6 +6,7 @@ config MIPS
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_UPROBES
@@ -34,6 +35,7 @@ config MIPS
 	select GENERIC_SCHED_CLOCK if !CAVIUM_OCTEON_SOC
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
+	select GUP_GET_PTE_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
 	select HANDLE_DOMAIN_IRQ
 	select HAVE_ARCH_COMPILER_H
 	select HAVE_ARCH_JUMP_LABEL
@@ -55,6 +57,7 @@ config MIPS
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
+	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 4ccb465ef3f2..7d27194e3b45 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -20,6 +20,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 #include <asm/pgtable-bits.h>
+#include <asm/cpu-features.h>
 
 struct mm_struct;
 struct vm_area_struct;
@@ -626,6 +627,8 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+#define gup_fast_permitted(start, end)	(!cpu_has_dc_aliases)
+
 #include <asm-generic/pgtable.h>
 
 /*
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index f34d7ff5eb60..1e8d335025d7 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -7,7 +7,6 @@ obj-y				+= cache.o
 obj-y				+= context.o
 obj-y				+= extable.o
 obj-y				+= fault.o
-obj-y				+= gup.o
 obj-y				+= init.o
 obj-y				+= mmap.o
 obj-y				+= page.o
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
deleted file mode 100644
index 4c2b4483683c..000000000000
--- a/arch/mips/mm/gup.c
+++ /dev/null
@@ -1,303 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for MIPS
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- * Copyright (C) 2011 Ralf Baechle
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <linux/swap.h>
-#include <linux/hugetlb.h>
-
-#include <asm/cpu-features.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#else
-	return READ_ONCE(*ptep);
-#endif
-}
-
-static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t *ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if (!pte_present(pte) ||
-		    pte_special(pte) || (write && !pte_write(pte))) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		SetPageReferenced(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	pte_unmap(ptep - 1);
-	return 1;
-}
-
-static inline void get_head_page_multiple(struct page *page, int nr)
-{
-	VM_BUG_ON(page != compound_head(page));
-	VM_BUG_ON(page_count(page) = 0);
-	page_ref_add(page, nr);
-	SetPageReferenced(page);
-}
-
-static int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pmd;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_huge(pmd))) {
-			if (!gup_huge_pmd(pmd, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pte_range(pmd, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pud;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_huge(pud))) {
-			if (!gup_huge_pud(pud, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pmd_range(pud, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch
-	 * size will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the page and take a ref on it.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int ret, nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start || cpu_has_dc_aliases)
-		goto slow_irqon;
-
-	/* XXX: batch / limit 'nr' */
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-slow:
-	local_irq_enable();
-
-slow_irqon:
-	/* Try to get the remaining pages with get_user_pages */
-	start += nr << PAGE_SHIFT;
-	pages += nr;
-
-	ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
-				      pages, gup_flags);
-
-	/* Have to be a bit careful with return values */
-	if (nr > 0) {
-		if (ret < 0)
-			ret = nr;
-		else
-			ret += nr;
-	}
-	return ret;
-}
-- 
2.20.1

[PATCH 05/16] MIPS: use the generic get_user_pages_fast code

[Christoph Hellwig]

The mips code is mostly equivalent to the generic one, minus various
bugfixes and an arch override for gup_fast_permitted.

Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has
pte_special and pte_mkspecial implemented and used in the existing
gup code.  They are no-op stubs, though which makes me a little unsure
if this is really right thing to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/Kconfig               |   3 +
 arch/mips/include/asm/pgtable.h |   3 +
 arch/mips/mm/Makefile           |   1 -
 arch/mips/mm/gup.c              | 303 --------------------------------
 4 files changed, 6 insertions(+), 304 deletions(-)
 delete mode 100644 arch/mips/mm/gup.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 70d3200476bf..64108a2a16d4 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,6 +6,7 @@ config MIPS
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_UPROBES
@@ -34,6 +35,7 @@ config MIPS
 	select GENERIC_SCHED_CLOCK if !CAVIUM_OCTEON_SOC
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
+	select GUP_GET_PTE_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
 	select HANDLE_DOMAIN_IRQ
 	select HAVE_ARCH_COMPILER_H
 	select HAVE_ARCH_JUMP_LABEL
@@ -55,6 +57,7 @@ config MIPS
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
+	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 4ccb465ef3f2..7d27194e3b45 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -20,6 +20,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 #include <asm/pgtable-bits.h>
+#include <asm/cpu-features.h>
 
 struct mm_struct;
 struct vm_area_struct;
@@ -626,6 +627,8 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+#define gup_fast_permitted(start, end)	(!cpu_has_dc_aliases)
+
 #include <asm-generic/pgtable.h>
 
 /*
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index f34d7ff5eb60..1e8d335025d7 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -7,7 +7,6 @@ obj-y				+= cache.o
 obj-y				+= context.o
 obj-y				+= extable.o
 obj-y				+= fault.o
-obj-y				+= gup.o
 obj-y				+= init.o
 obj-y				+= mmap.o
 obj-y				+= page.o
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
deleted file mode 100644
index 4c2b4483683c..000000000000
--- a/arch/mips/mm/gup.c
+++ /dev/null
@@ -1,303 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for MIPS
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- * Copyright (C) 2011 Ralf Baechle
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <linux/swap.h>
-#include <linux/hugetlb.h>
-
-#include <asm/cpu-features.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#else
-	return READ_ONCE(*ptep);
-#endif
-}
-
-static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t *ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if (!pte_present(pte) ||
-		    pte_special(pte) || (write && !pte_write(pte))) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		SetPageReferenced(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	pte_unmap(ptep - 1);
-	return 1;
-}
-
-static inline void get_head_page_multiple(struct page *page, int nr)
-{
-	VM_BUG_ON(page != compound_head(page));
-	VM_BUG_ON(page_count(page) == 0);
-	page_ref_add(page, nr);
-	SetPageReferenced(page);
-}
-
-static int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pmd;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_huge(pmd))) {
-			if (!gup_huge_pmd(pmd, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pte_range(pmd, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pud;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_huge(pud))) {
-			if (!gup_huge_pud(pud, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pmd_range(pud, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch
-	 * size will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the page and take a ref on it.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int ret, nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start || cpu_has_dc_aliases)
-		goto slow_irqon;
-
-	/* XXX: batch / limit 'nr' */
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-slow:
-	local_irq_enable();
-
-slow_irqon:
-	/* Try to get the remaining pages with get_user_pages */
-	start += nr << PAGE_SHIFT;
-	pages += nr;
-
-	ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
-				      pages, gup_flags);
-
-	/* Have to be a bit careful with return values */
-	if (nr > 0) {
-		if (ret < 0)
-			ret = nr;
-		else
-			ret += nr;
-	}
-	return ret;
-}
-- 
2.20.1

[PATCH 05/16] MIPS: use the generic get_user_pages_fast code

[Christoph Hellwig]

The mips code is mostly equivalent to the generic one, minus various
bugfixes and an arch override for gup_fast_permitted.

Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has
pte_special and pte_mkspecial implemented and used in the existing
gup code.  They are no-op stubs, though which makes me a little unsure
if this is really right thing to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/Kconfig               |   3 +
 arch/mips/include/asm/pgtable.h |   3 +
 arch/mips/mm/Makefile           |   1 -
 arch/mips/mm/gup.c              | 303 --------------------------------
 4 files changed, 6 insertions(+), 304 deletions(-)
 delete mode 100644 arch/mips/mm/gup.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 70d3200476bf..64108a2a16d4 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,6 +6,7 @@ config MIPS
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_UPROBES
@@ -34,6 +35,7 @@ config MIPS
 	select GENERIC_SCHED_CLOCK if !CAVIUM_OCTEON_SOC
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
+	select GUP_GET_PTE_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
 	select HANDLE_DOMAIN_IRQ
 	select HAVE_ARCH_COMPILER_H
 	select HAVE_ARCH_JUMP_LABEL
@@ -55,6 +57,7 @@ config MIPS
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
+	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 4ccb465ef3f2..7d27194e3b45 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -20,6 +20,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 #include <asm/pgtable-bits.h>
+#include <asm/cpu-features.h>
 
 struct mm_struct;
 struct vm_area_struct;
@@ -626,6 +627,8 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+#define gup_fast_permitted(start, end)	(!cpu_has_dc_aliases)
+
 #include <asm-generic/pgtable.h>
 
 /*
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index f34d7ff5eb60..1e8d335025d7 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -7,7 +7,6 @@ obj-y				+= cache.o
 obj-y				+= context.o
 obj-y				+= extable.o
 obj-y				+= fault.o
-obj-y				+= gup.o
 obj-y				+= init.o
 obj-y				+= mmap.o
 obj-y				+= page.o
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
deleted file mode 100644
index 4c2b4483683c..000000000000
--- a/arch/mips/mm/gup.c
+++ /dev/null
@@ -1,303 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for MIPS
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- * Copyright (C) 2011 Ralf Baechle
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <linux/swap.h>
-#include <linux/hugetlb.h>
-
-#include <asm/cpu-features.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#else
-	return READ_ONCE(*ptep);
-#endif
-}
-
-static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t *ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if (!pte_present(pte) ||
-		    pte_special(pte) || (write && !pte_write(pte))) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		SetPageReferenced(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	pte_unmap(ptep - 1);
-	return 1;
-}
-
-static inline void get_head_page_multiple(struct page *page, int nr)
-{
-	VM_BUG_ON(page != compound_head(page));
-	VM_BUG_ON(page_count(page) == 0);
-	page_ref_add(page, nr);
-	SetPageReferenced(page);
-}
-
-static int gup_huge_pmd(pmd_t pmd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pmd;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_huge(pmd))) {
-			if (!gup_huge_pmd(pmd, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pte_range(pmd, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t pud, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	pte_t pte = *(pte_t *)&pud;
-	struct page *head, *page;
-	int refs;
-
-	if (write && !pte_write(pte))
-		return 0;
-	/* hugepages are never "special" */
-	VM_BUG_ON(pte_special(pte));
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	get_head_page_multiple(head, refs);
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_huge(pud))) {
-			if (!gup_huge_pud(pud, addr, next, write, pages,nr))
-				return 0;
-		} else {
-			if (!gup_pmd_range(pud, addr, next, write, pages,nr))
-				return 0;
-		}
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch
-	 * size will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the page and take a ref on it.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int ret, nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start || cpu_has_dc_aliases)
-		goto slow_irqon;
-
-	/* XXX: batch / limit 'nr' */
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-slow:
-	local_irq_enable();
-
-slow_irqon:
-	/* Try to get the remaining pages with get_user_pages */
-	start += nr << PAGE_SHIFT;
-	pages += nr;
-
-	ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
-				      pages, gup_flags);
-
-	/* Have to be a bit careful with return values */
-	if (nr > 0) {
-		if (ret < 0)
-			ret = nr;
-		else
-			ret += nr;
-	}
-	return ret;
-}
-- 
2.20.1

[PATCH 06/16] sh: add the missing pud_page definition

[Christoph Hellwig]

sh only had pud_page_vaddr, but not pud_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/include/asm/pgtable-3level.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 7d8587eb65ff..8ff6fb6b4d19 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -37,6 +37,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 {
 	return pud_val(pud);
 }
+#define pud_page(pud)		virt_to_page((void *)pud_page_vaddr(pud))
 
 #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
-- 
2.20.1

[PATCH 06/16] sh: add the missing pud_page definition

[Christoph Hellwig]

sh only had pud_page_vaddr, but not pud_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/include/asm/pgtable-3level.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 7d8587eb65ff..8ff6fb6b4d19 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -37,6 +37,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 {
 	return pud_val(pud);
 }
+#define pud_page(pud)		virt_to_page((void *)pud_page_vaddr(pud))
 
 #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
-- 
2.20.1

[PATCH 06/16] sh: add the missing pud_page definition

[Christoph Hellwig]

sh only had pud_page_vaddr, but not pud_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/include/asm/pgtable-3level.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 7d8587eb65ff..8ff6fb6b4d19 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -37,6 +37,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 {
 	return pud_val(pud);
 }
+#define pud_page(pud)		virt_to_page((void *)pud_page_vaddr(pud))
 
 #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
-- 
2.20.1

[PATCH 07/16] sh: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sh code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/Kconfig               |   2 +
 arch/sh/include/asm/pgtable.h |  37 +++++
 arch/sh/mm/Makefile           |   2 +-
 arch/sh/mm/gup.c              | 277 ----------------------------------
 4 files changed, 40 insertions(+), 278 deletions(-)
 delete mode 100644 arch/sh/mm/gup.c

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index b77f512bb176..6fddfc3c9710 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,6 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
+	select HAVE_GENERIC_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
@@ -63,6 +64,7 @@ config SUPERH
 config SUPERH32
 	def_bool "$(ARCH)" = "sh"
 	select ARCH_32BIT_OFF_T
+	select GUP_GET_PTE_LOW_HIGH if X2TLB
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_IOREMAP_PROT if MMU && !X2TLB
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 3587103afe59..9085d1142fa3 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -149,6 +149,43 @@ extern void paging_init(void);
 extern void page_table_range_init(unsigned long start, unsigned long end,
 				  pgd_t *pgd);
 
+static inline bool __pte_access_permitted(pte_t pte, u64 prot)
+{
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) = prot;
+}
+
+#ifdef CONFIG_X2TLB
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT;
+
+	prot |= _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
+	if (write)
+		prot |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
+	return __pte_access_permitted(pte, prot);
+}
+#elif defined(CONFIG_SUPERH64)
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
+
+	if (write)
+		prot |= _PAGE_WRITE;
+	return __pte_access_permitted(pte, prot);
+}
+#else
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER;
+
+	if (write)
+		prot |= _PAGE_RW;
+	return __pte_access_permitted(pte, prot);
+}
+#endif
+
+#define pte_access_permitted pte_access_permitted
+
 /* arch/sh/mm/mmap.c */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index fbe5e79751b3..5051b38fd5b6 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -17,7 +17,7 @@ cacheops-$(CONFIG_CPU_SHX3)		+= cache-shx3.o
 obj-y			+= $(cacheops-y)
 
 mmu-y			:= nommu.o extable_32.o
-mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o gup.o ioremap.o kmap.o \
+mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o ioremap.o kmap.o \
 			   pgtable.o tlbex_$(BITS).o tlbflush_$(BITS).o
 
 obj-y			+= $(mmu-y)
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c
deleted file mode 100644
index 277c882f7489..000000000000
--- a/arch/sh/mm/gup.c
+++ /dev/null
@@ -1,277 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for SuperH
- *
- * Copyright (C) 2009 - 2010  Paul Mundt
- *
- * Cloned from the x86 and PowerPC versions, by:
- *
- *	Copyright (C) 2008 Nick Piggin
- *	Copyright (C) 2008 Novell Inc.
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#ifndef CONFIG_X2TLB
-	return READ_ONCE(*ptep);
-#else
-	/*
-	 * With get_user_pages_fast, we walk down the pagetables without
-	 * taking any locks.  For this we would like to load the pointers
-	 * atomically, but that is not possible with 64-bit PTEs.  What
-	 * we do have is the guarantee that a pte will only either go
-	 * from not present to present, or present to not present or both
-	 * -- it will not switch to a completely different present page
-	 * without a TLB flush in between; something that we are blocking
-	 * by holding interrupts off.
-	 *
-	 * Setting ptes from not present to present goes:
-	 * ptep->pte_high = h;
-	 * smp_wmb();
-	 * ptep->pte_low = l;
-	 *
-	 * And present to not present goes:
-	 * ptep->pte_low = 0;
-	 * smp_wmb();
-	 * ptep->pte_high = 0;
-	 *
-	 * We must ensure here that the load of pte_low sees l iff pte_high
-	 * sees h. We load pte_high *after* loading pte_low, which ensures we
-	 * don't see an older value of pte_high.  *Then* we recheck pte_low,
-	 * which ensures that we haven't picked up a changed pte high. We might
-	 * have got rubbish values from pte_low and pte_high, but we are
-	 * guaranteed that pte_low will not have the present bit set *unless*
-	 * it is 'l'. And get_user_pages_fast only operates on present ptes, so
-	 * we're safe.
-	 *
-	 * gup_get_pte should not be used or copied outside gup.c without being
-	 * very careful -- it does not atomically load the pte or anything that
-	 * is likely to be useful for you.
-	 */
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#endif
-}
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	u64 mask, result;
-	pte_t *ptep;
-
-#ifdef CONFIG_X2TLB
-	result = _PAGE_PRESENT | _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
-	if (write)
-		result |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
-#elif defined(CONFIG_SUPERH64)
-	result = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
-	if (write)
-		result |= _PAGE_WRITE;
-#else
-	result = _PAGE_PRESENT | _PAGE_USER;
-	if (write)
-		result |= _PAGE_RW;
-#endif
-
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if ((pte_val(pte) & mask) != result) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		__flush_anon_page(page, addr);
-		flush_dcache_page(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-	pte_unmap(ptep - 1);
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (!gup_pte_range(pmd, addr, next, write, pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start)
-		goto slow_irqon;
-
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-slow_irqon:
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

[PATCH 07/16] sh: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sh code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/Kconfig               |   2 +
 arch/sh/include/asm/pgtable.h |  37 +++++
 arch/sh/mm/Makefile           |   2 +-
 arch/sh/mm/gup.c              | 277 ----------------------------------
 4 files changed, 40 insertions(+), 278 deletions(-)
 delete mode 100644 arch/sh/mm/gup.c

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index b77f512bb176..6fddfc3c9710 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,6 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
+	select HAVE_GENERIC_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
@@ -63,6 +64,7 @@ config SUPERH
 config SUPERH32
 	def_bool "$(ARCH)" = "sh"
 	select ARCH_32BIT_OFF_T
+	select GUP_GET_PTE_LOW_HIGH if X2TLB
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_IOREMAP_PROT if MMU && !X2TLB
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 3587103afe59..9085d1142fa3 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -149,6 +149,43 @@ extern void paging_init(void);
 extern void page_table_range_init(unsigned long start, unsigned long end,
 				  pgd_t *pgd);
 
+static inline bool __pte_access_permitted(pte_t pte, u64 prot)
+{
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot;
+}
+
+#ifdef CONFIG_X2TLB
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT;
+
+	prot |= _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
+	if (write)
+		prot |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
+	return __pte_access_permitted(pte, prot);
+}
+#elif defined(CONFIG_SUPERH64)
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
+
+	if (write)
+		prot |= _PAGE_WRITE;
+	return __pte_access_permitted(pte, prot);
+}
+#else
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER;
+
+	if (write)
+		prot |= _PAGE_RW;
+	return __pte_access_permitted(pte, prot);
+}
+#endif
+
+#define pte_access_permitted pte_access_permitted
+
 /* arch/sh/mm/mmap.c */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index fbe5e79751b3..5051b38fd5b6 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -17,7 +17,7 @@ cacheops-$(CONFIG_CPU_SHX3)		+= cache-shx3.o
 obj-y			+= $(cacheops-y)
 
 mmu-y			:= nommu.o extable_32.o
-mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o gup.o ioremap.o kmap.o \
+mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o ioremap.o kmap.o \
 			   pgtable.o tlbex_$(BITS).o tlbflush_$(BITS).o
 
 obj-y			+= $(mmu-y)
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c
deleted file mode 100644
index 277c882f7489..000000000000
--- a/arch/sh/mm/gup.c
+++ /dev/null
@@ -1,277 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for SuperH
- *
- * Copyright (C) 2009 - 2010  Paul Mundt
- *
- * Cloned from the x86 and PowerPC versions, by:
- *
- *	Copyright (C) 2008 Nick Piggin
- *	Copyright (C) 2008 Novell Inc.
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#ifndef CONFIG_X2TLB
-	return READ_ONCE(*ptep);
-#else
-	/*
-	 * With get_user_pages_fast, we walk down the pagetables without
-	 * taking any locks.  For this we would like to load the pointers
-	 * atomically, but that is not possible with 64-bit PTEs.  What
-	 * we do have is the guarantee that a pte will only either go
-	 * from not present to present, or present to not present or both
-	 * -- it will not switch to a completely different present page
-	 * without a TLB flush in between; something that we are blocking
-	 * by holding interrupts off.
-	 *
-	 * Setting ptes from not present to present goes:
-	 * ptep->pte_high = h;
-	 * smp_wmb();
-	 * ptep->pte_low = l;
-	 *
-	 * And present to not present goes:
-	 * ptep->pte_low = 0;
-	 * smp_wmb();
-	 * ptep->pte_high = 0;
-	 *
-	 * We must ensure here that the load of pte_low sees l iff pte_high
-	 * sees h. We load pte_high *after* loading pte_low, which ensures we
-	 * don't see an older value of pte_high.  *Then* we recheck pte_low,
-	 * which ensures that we haven't picked up a changed pte high. We might
-	 * have got rubbish values from pte_low and pte_high, but we are
-	 * guaranteed that pte_low will not have the present bit set *unless*
-	 * it is 'l'. And get_user_pages_fast only operates on present ptes, so
-	 * we're safe.
-	 *
-	 * gup_get_pte should not be used or copied outside gup.c without being
-	 * very careful -- it does not atomically load the pte or anything that
-	 * is likely to be useful for you.
-	 */
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#endif
-}
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	u64 mask, result;
-	pte_t *ptep;
-
-#ifdef CONFIG_X2TLB
-	result = _PAGE_PRESENT | _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
-	if (write)
-		result |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
-#elif defined(CONFIG_SUPERH64)
-	result = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
-	if (write)
-		result |= _PAGE_WRITE;
-#else
-	result = _PAGE_PRESENT | _PAGE_USER;
-	if (write)
-		result |= _PAGE_RW;
-#endif
-
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if ((pte_val(pte) & mask) != result) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		__flush_anon_page(page, addr);
-		flush_dcache_page(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-	pte_unmap(ptep - 1);
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (!gup_pte_range(pmd, addr, next, write, pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start)
-		goto slow_irqon;
-
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-slow_irqon:
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

[PATCH 07/16] sh: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sh code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/Kconfig               |   2 +
 arch/sh/include/asm/pgtable.h |  37 +++++
 arch/sh/mm/Makefile           |   2 +-
 arch/sh/mm/gup.c              | 277 ----------------------------------
 4 files changed, 40 insertions(+), 278 deletions(-)
 delete mode 100644 arch/sh/mm/gup.c

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index b77f512bb176..6fddfc3c9710 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,6 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
+	select HAVE_GENERIC_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
@@ -63,6 +64,7 @@ config SUPERH
 config SUPERH32
 	def_bool "$(ARCH)" = "sh"
 	select ARCH_32BIT_OFF_T
+	select GUP_GET_PTE_LOW_HIGH if X2TLB
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_IOREMAP_PROT if MMU && !X2TLB
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 3587103afe59..9085d1142fa3 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -149,6 +149,43 @@ extern void paging_init(void);
 extern void page_table_range_init(unsigned long start, unsigned long end,
 				  pgd_t *pgd);
 
+static inline bool __pte_access_permitted(pte_t pte, u64 prot)
+{
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot;
+}
+
+#ifdef CONFIG_X2TLB
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT;
+
+	prot |= _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
+	if (write)
+		prot |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
+	return __pte_access_permitted(pte, prot);
+}
+#elif defined(CONFIG_SUPERH64)
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
+
+	if (write)
+		prot |= _PAGE_WRITE;
+	return __pte_access_permitted(pte, prot);
+}
+#else
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot = _PAGE_PRESENT | _PAGE_USER;
+
+	if (write)
+		prot |= _PAGE_RW;
+	return __pte_access_permitted(pte, prot);
+}
+#endif
+
+#define pte_access_permitted pte_access_permitted
+
 /* arch/sh/mm/mmap.c */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index fbe5e79751b3..5051b38fd5b6 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -17,7 +17,7 @@ cacheops-$(CONFIG_CPU_SHX3)		+= cache-shx3.o
 obj-y			+= $(cacheops-y)
 
 mmu-y			:= nommu.o extable_32.o
-mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o gup.o ioremap.o kmap.o \
+mmu-$(CONFIG_MMU)	:= extable_$(BITS).o fault.o ioremap.o kmap.o \
 			   pgtable.o tlbex_$(BITS).o tlbflush_$(BITS).o
 
 obj-y			+= $(mmu-y)
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c
deleted file mode 100644
index 277c882f7489..000000000000
--- a/arch/sh/mm/gup.c
+++ /dev/null
@@ -1,277 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for SuperH
- *
- * Copyright (C) 2009 - 2010  Paul Mundt
- *
- * Cloned from the x86 and PowerPC versions, by:
- *
- *	Copyright (C) 2008 Nick Piggin
- *	Copyright (C) 2008 Novell Inc.
- */
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/highmem.h>
-#include <asm/pgtable.h>
-
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
-#ifndef CONFIG_X2TLB
-	return READ_ONCE(*ptep);
-#else
-	/*
-	 * With get_user_pages_fast, we walk down the pagetables without
-	 * taking any locks.  For this we would like to load the pointers
-	 * atomically, but that is not possible with 64-bit PTEs.  What
-	 * we do have is the guarantee that a pte will only either go
-	 * from not present to present, or present to not present or both
-	 * -- it will not switch to a completely different present page
-	 * without a TLB flush in between; something that we are blocking
-	 * by holding interrupts off.
-	 *
-	 * Setting ptes from not present to present goes:
-	 * ptep->pte_high = h;
-	 * smp_wmb();
-	 * ptep->pte_low = l;
-	 *
-	 * And present to not present goes:
-	 * ptep->pte_low = 0;
-	 * smp_wmb();
-	 * ptep->pte_high = 0;
-	 *
-	 * We must ensure here that the load of pte_low sees l iff pte_high
-	 * sees h. We load pte_high *after* loading pte_low, which ensures we
-	 * don't see an older value of pte_high.  *Then* we recheck pte_low,
-	 * which ensures that we haven't picked up a changed pte high. We might
-	 * have got rubbish values from pte_low and pte_high, but we are
-	 * guaranteed that pte_low will not have the present bit set *unless*
-	 * it is 'l'. And get_user_pages_fast only operates on present ptes, so
-	 * we're safe.
-	 *
-	 * gup_get_pte should not be used or copied outside gup.c without being
-	 * very careful -- it does not atomically load the pte or anything that
-	 * is likely to be useful for you.
-	 */
-	pte_t pte;
-
-retry:
-	pte.pte_low = ptep->pte_low;
-	smp_rmb();
-	pte.pte_high = ptep->pte_high;
-	smp_rmb();
-	if (unlikely(pte.pte_low != ptep->pte_low))
-		goto retry;
-
-	return pte;
-#endif
-}
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	u64 mask, result;
-	pte_t *ptep;
-
-#ifdef CONFIG_X2TLB
-	result = _PAGE_PRESENT | _PAGE_EXT(_PAGE_EXT_KERN_READ | _PAGE_EXT_USER_READ);
-	if (write)
-		result |= _PAGE_EXT(_PAGE_EXT_KERN_WRITE | _PAGE_EXT_USER_WRITE);
-#elif defined(CONFIG_SUPERH64)
-	result = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
-	if (write)
-		result |= _PAGE_WRITE;
-#else
-	result = _PAGE_PRESENT | _PAGE_USER;
-	if (write)
-		result |= _PAGE_RW;
-#endif
-
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_map(&pmd, addr);
-	do {
-		pte_t pte = gup_get_pte(ptep);
-		struct page *page;
-
-		if ((pte_val(pte) & mask) != result) {
-			pte_unmap(ptep);
-			return 0;
-		}
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
-		get_page(page);
-		__flush_anon_page(page, addr);
-		flush_dcache_page(page);
-		pages[*nr] = page;
-		(*nr)++;
-
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-	pte_unmap(ptep - 1);
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (!gup_pte_range(pmd, addr, next, write, pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-			int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	unsigned long flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-	if (unlikely(!access_ok((void __user *)start, len)))
-		return 0;
-
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables and pages from being freed.
-	 */
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * Attempt to pin user pages in memory without taking mm->mmap_sem.
- * If not successful, it will fall back to taking the lock and
- * calling get_user_pages().
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-
-	end = start + len;
-	if (end < start)
-		goto slow_irqon;
-
-	local_irq_disable();
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-slow_irqon:
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

[PATCH 08/16] sparc64: add the missing pgd_page definition

[Christoph Hellwig]

sparc64 only had pgd_page_vaddr, but not pgd_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/include/asm/pgtable_64.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 22500c3be7a9..dcf970e82262 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -861,6 +861,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 #define pud_clear(pudp)			(pud_val(*(pudp)) = 0UL)
 #define pgd_page_vaddr(pgd)		\
 	((unsigned long) __va(pgd_val(pgd)))
+#define pgd_page(pgd)			virt_to_page(__va(pgd_val(pgd)))
 #define pgd_present(pgd)		(pgd_val(pgd) != 0U)
 #define pgd_clear(pgdp)			(pgd_val(*(pgdp)) = 0UL)
 
-- 
2.20.1

[PATCH 08/16] sparc64: add the missing pgd_page definition

[Christoph Hellwig]

sparc64 only had pgd_page_vaddr, but not pgd_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/include/asm/pgtable_64.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 22500c3be7a9..dcf970e82262 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -861,6 +861,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 #define pud_clear(pudp)			(pud_val(*(pudp)) = 0UL)
 #define pgd_page_vaddr(pgd)		\
 	((unsigned long) __va(pgd_val(pgd)))
+#define pgd_page(pgd)			virt_to_page(__va(pgd_val(pgd)))
 #define pgd_present(pgd)		(pgd_val(pgd) != 0U)
 #define pgd_clear(pgdp)			(pgd_val(*(pgdp)) = 0UL)
 
-- 
2.20.1

[PATCH 08/16] sparc64: add the missing pgd_page definition

[Christoph Hellwig]

sparc64 only had pgd_page_vaddr, but not pgd_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/include/asm/pgtable_64.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 22500c3be7a9..dcf970e82262 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -861,6 +861,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 #define pud_clear(pudp)			(pud_val(*(pudp)) = 0UL)
 #define pgd_page_vaddr(pgd)		\
 	((unsigned long) __va(pgd_val(pgd)))
+#define pgd_page(pgd)			virt_to_page(__va(pgd_val(pgd)))
 #define pgd_present(pgd)		(pgd_val(pgd) != 0U)
 #define pgd_clear(pgdp)			(pgd_val(*(pgdp)) = 0UL)
 
-- 
2.20.1

Re: [PATCH 08/16] sparc64: add the missing pgd_page definition

[Linus Torvalds]

Both sparc64 and sh had this pattern, but now that I look at it more
closely, I think your version is wrong, or at least nonoptimal.

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> +#define pgd_page(pgd)                  virt_to_page(__va(pgd_val(pgd)))

Going through the virtual address is potentially very inefficient, and
might in some cases just be wrong (ie it's definitely wrong for
HIGHMEM style setups).

It would likely be much better to go through the physical address and
use "pfn_to_page()". I realize that we don't have a "pgd to physical",
but neither do we really have a "pgd to virtual", and your
"__va(pgd_val(x))" thing is not at allguaranteed to work. You're
basically assuming that "pgd_val(x)" is the physical address, which is
likely not entirely incorrect, but it should be checked by the
architecture people.

The pgd value could easily have high bits with meaning, which would
also potentially screw up the __va(x) model.

So I thgink this would be better done with

     #define pgd_page(pgd)    pfn_to_page(pgd_pfn(pgd))

where that "pgd_pfn()" would need to be a new (but likely very
trivial) function. That's what we do for pte_pfn().

IOW, it would likely end up something like

  #define pgd_to_pfn(pgd) (pgd_val(x) >> PFN_PGD_SHIFT)

David?

                  Linus

Re: [PATCH 08/16] sparc64: add the missing pgd_page definition

[Linus Torvalds]

Both sparc64 and sh had this pattern, but now that I look at it more
closely, I think your version is wrong, or at least nonoptimal.

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> +#define pgd_page(pgd)                  virt_to_page(__va(pgd_val(pgd)))

Going through the virtual address is potentially very inefficient, and
might in some cases just be wrong (ie it's definitely wrong for
HIGHMEM style setups).

It would likely be much better to go through the physical address and
use "pfn_to_page()". I realize that we don't have a "pgd to physical",
but neither do we really have a "pgd to virtual", and your
"__va(pgd_val(x))" thing is not at allguaranteed to work. You're
basically assuming that "pgd_val(x)" is the physical address, which is
likely not entirely incorrect, but it should be checked by the
architecture people.

The pgd value could easily have high bits with meaning, which would
also potentially screw up the __va(x) model.

So I thgink this would be better done with

     #define pgd_page(pgd)    pfn_to_page(pgd_pfn(pgd))

where that "pgd_pfn()" would need to be a new (but likely very
trivial) function. That's what we do for pte_pfn().

IOW, it would likely end up something like

  #define pgd_to_pfn(pgd) (pgd_val(x) >> PFN_PGD_SHIFT)

David?

                  Linus

Re: [PATCH 08/16] sparc64: add the missing pgd_page definition

[Linus Torvalds]

Both sparc64 and sh had this pattern, but now that I look at it more
closely, I think your version is wrong, or at least nonoptimal.

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> +#define pgd_page(pgd)                  virt_to_page(__va(pgd_val(pgd)))

Going through the virtual address is potentially very inefficient, and
might in some cases just be wrong (ie it's definitely wrong for
HIGHMEM style setups).

It would likely be much better to go through the physical address and
use "pfn_to_page()". I realize that we don't have a "pgd to physical",
but neither do we really have a "pgd to virtual", and your
"__va(pgd_val(x))" thing is not at allguaranteed to work. You're
basically assuming that "pgd_val(x)" is the physical address, which is
likely not entirely incorrect, but it should be checked by the
architecture people.

The pgd value could easily have high bits with meaning, which would
also potentially screw up the __va(x) model.

So I thgink this would be better done with

     #define pgd_page(pgd)    pfn_to_page(pgd_pfn(pgd))

where that "pgd_pfn()" would need to be a new (but likely very
trivial) function. That's what we do for pte_pfn().

IOW, it would likely end up something like

  #define pgd_to_pfn(pgd) (pgd_val(x) >> PFN_PGD_SHIFT)

David?

                  Linus

Re: [PATCH 08/16] sparc64: add the missing pgd_page definition

[Linus Torvalds]

Both sparc64 and sh had this pattern, but now that I look at it more
closely, I think your version is wrong, or at least nonoptimal.

On Sat, Jun 1, 2019 at 12:50 AM Christoph Hellwig <hch@lst.de> wrote:
>
> +#define pgd_page(pgd)                  virt_to_page(__va(pgd_val(pgd)))

Going through the virtual address is potentially very inefficient, and
might in some cases just be wrong (ie it's definitely wrong for
HIGHMEM style setups).

It would likely be much better to go through the physical address and
use "pfn_to_page()". I realize that we don't have a "pgd to physical",
but neither do we really have a "pgd to virtual", and your
"__va(pgd_val(x))" thing is not at allguaranteed to work. You're
basically assuming that "pgd_val(x)" is the physical address, which is
likely not entirely incorrect, but it should be checked by the
architecture people.

The pgd value could easily have high bits with meaning, which would
also potentially screw up the __va(x) model.

So I thgink this would be better done with

     #define pgd_page(pgd)    pfn_to_page(pgd_pfn(pgd))

where that "pgd_pfn()" would need to be a new (but likely very
trivial) function. That's what we do for pte_pfn().

IOW, it would likely end up something like

  #define pgd_to_pfn(pgd) (pgd_val(x) >> PFN_PGD_SHIFT)

David?

                  Linus

Re: [PATCH 08/16] sparc64: add the missing pgd_page definition

[Christoph Hellwig]

On Sat, Jun 01, 2019 at 09:28:54AM -0700, Linus Torvalds wrote:
> Both sparc64 and sh had this pattern, but now that I look at it more
> closely, I think your version is wrong, or at least nonoptimal.

I bet it is.  Then again these symbols are just required for the code
to compile, as neither sparc64 nor sh actually use the particular
variant of huge pages we need it for.  Then again even actually dead
code should better be not too buggy if it isn't just a stub.

> So I thgink this would be better done with
> 
>      #define pgd_page(pgd)    pfn_to_page(pgd_pfn(pgd))
> 
> where that "pgd_pfn()" would need to be a new (but likely very
> trivial) function. That's what we do for pte_pfn().
> 
> IOW, it would likely end up something like
> 
>   #define pgd_to_pfn(pgd) (pgd_val(x) >> PFN_PGD_SHIFT)

True.  I guess it would be best if we could get most if not all
architectures to use common versions of these macros so that we have
the issue settled once.

Re: [PATCH 08/16] sparc64: add the missing pgd_page definition

[Christoph Hellwig]

On Sat, Jun 01, 2019 at 09:28:54AM -0700, Linus Torvalds wrote:
> Both sparc64 and sh had this pattern, but now that I look at it more
> closely, I think your version is wrong, or at least nonoptimal.

I bet it is.  Then again these symbols are just required for the code
to compile, as neither sparc64 nor sh actually use the particular
variant of huge pages we need it for.  Then again even actually dead
code should better be not too buggy if it isn't just a stub.

> So I thgink this would be better done with
> 
>      #define pgd_page(pgd)    pfn_to_page(pgd_pfn(pgd))
> 
> where that "pgd_pfn()" would need to be a new (but likely very
> trivial) function. That's what we do for pte_pfn().
> 
> IOW, it would likely end up something like
> 
>   #define pgd_to_pfn(pgd) (pgd_val(x) >> PFN_PGD_SHIFT)

True.  I guess it would be best if we could get most if not all
architectures to use common versions of these macros so that we have
the issue settled once.

Re: [PATCH 08/16] sparc64: add the missing pgd_page definition

[Christoph Hellwig]

On Sat, Jun 01, 2019 at 09:28:54AM -0700, Linus Torvalds wrote:
> Both sparc64 and sh had this pattern, but now that I look at it more
> closely, I think your version is wrong, or at least nonoptimal.

I bet it is.  Then again these symbols are just required for the code
to compile, as neither sparc64 nor sh actually use the particular
variant of huge pages we need it for.  Then again even actually dead
code should better be not too buggy if it isn't just a stub.

> So I thgink this would be better done with
> 
>      #define pgd_page(pgd)    pfn_to_page(pgd_pfn(pgd))
> 
> where that "pgd_pfn()" would need to be a new (but likely very
> trivial) function. That's what we do for pte_pfn().
> 
> IOW, it would likely end up something like
> 
>   #define pgd_to_pfn(pgd) (pgd_val(x) >> PFN_PGD_SHIFT)

True.  I guess it would be best if we could get most if not all
architectures to use common versions of these macros so that we have
the issue settled once.

[PATCH 09/16] sparc64: define untagged_addr()

[Christoph Hellwig]

Add a helper to untag a user pointer.  This is needed for ADI support
in get_user_pages_fast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/include/asm/pgtable_64.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index dcf970e82262..a93eca29e85a 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1076,6 +1076,28 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 }
 #define io_remap_pfn_range io_remap_pfn_range 
 
+static inline unsigned long untagged_addr(unsigned long start)
+{
+	if (adi_capable()) {
+		long addr = start;
+
+		/* If userspace has passed a versioned address, kernel
+		 * will not find it in the VMAs since it does not store
+		 * the version tags in the list of VMAs. Storing version
+		 * tags in list of VMAs is impractical since they can be
+		 * changed any time from userspace without dropping into
+		 * kernel. Any address search in VMAs will be done with
+		 * non-versioned addresses. Ensure the ADI version bits
+		 * are dropped here by sign extending the last bit before
+		 * ADI bits. IOMMU does not implement version tags.
+		 */
+		return (addr << (long)adi_nbits()) >> (long)adi_nbits();
+	}
+
+	return start;
+}
+#define untagged_addr untagged_addr
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
-- 
2.20.1

[PATCH 09/16] sparc64: define untagged_addr()

[Christoph Hellwig]

Add a helper to untag a user pointer.  This is needed for ADI support
in get_user_pages_fast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/include/asm/pgtable_64.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index dcf970e82262..a93eca29e85a 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1076,6 +1076,28 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 }
 #define io_remap_pfn_range io_remap_pfn_range 
 
+static inline unsigned long untagged_addr(unsigned long start)
+{
+	if (adi_capable()) {
+		long addr = start;
+
+		/* If userspace has passed a versioned address, kernel
+		 * will not find it in the VMAs since it does not store
+		 * the version tags in the list of VMAs. Storing version
+		 * tags in list of VMAs is impractical since they can be
+		 * changed any time from userspace without dropping into
+		 * kernel. Any address search in VMAs will be done with
+		 * non-versioned addresses. Ensure the ADI version bits
+		 * are dropped here by sign extending the last bit before
+		 * ADI bits. IOMMU does not implement version tags.
+		 */
+		return (addr << (long)adi_nbits()) >> (long)adi_nbits();
+	}
+
+	return start;
+}
+#define untagged_addr untagged_addr
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
-- 
2.20.1

[PATCH 09/16] sparc64: define untagged_addr()

[Christoph Hellwig]

Add a helper to untag a user pointer.  This is needed for ADI support
in get_user_pages_fast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/include/asm/pgtable_64.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index dcf970e82262..a93eca29e85a 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1076,6 +1076,28 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 }
 #define io_remap_pfn_range io_remap_pfn_range 
 
+static inline unsigned long untagged_addr(unsigned long start)
+{
+	if (adi_capable()) {
+		long addr = start;
+
+		/* If userspace has passed a versioned address, kernel
+		 * will not find it in the VMAs since it does not store
+		 * the version tags in the list of VMAs. Storing version
+		 * tags in list of VMAs is impractical since they can be
+		 * changed any time from userspace without dropping into
+		 * kernel. Any address search in VMAs will be done with
+		 * non-versioned addresses. Ensure the ADI version bits
+		 * are dropped here by sign extending the last bit before
+		 * ADI bits. IOMMU does not implement version tags.
+		 */
+		return (addr << (long)adi_nbits()) >> (long)adi_nbits();
+	}
+
+	return start;
+}
+#define untagged_addr untagged_addr
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
-- 
2.20.1

[PATCH 10/16] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sparc64 code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/Kconfig                  |   1 +
 arch/sparc/include/asm/pgtable_64.h |  18 ++
 arch/sparc/mm/Makefile              |   2 +-
 arch/sparc/mm/gup.c                 | 340 ----------------------------
 4 files changed, 20 insertions(+), 341 deletions(-)
 delete mode 100644 arch/sparc/mm/gup.c

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 26ab6f5bbaaf..22435471f942 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,6 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
+	select HAVE_GENERIC_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index a93eca29e85a..2301ab5250e4 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
 }
 #define untagged_addr untagged_addr
 
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot;
+
+	if (tlb_type = hypervisor) {
+		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
+		if (prot)
+			prot |= _PAGE_WRITE_4V;
+	} else {
+		prot = _PAGE_PRESENT_4U | _PAGE_P_4U;
+		if (write)
+			prot |= _PAGE_WRITE_4U;
+	}
+
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) = prot;
+}
+#define pte_access_permitted pte_access_permitted
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
diff --git a/arch/sparc/mm/Makefile b/arch/sparc/mm/Makefile
index d39075b1e3b7..b078205b70e0 100644
--- a/arch/sparc/mm/Makefile
+++ b/arch/sparc/mm/Makefile
@@ -5,7 +5,7 @@
 asflags-y := -ansi
 ccflags-y := -Werror
 
-obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o gup.o
+obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o
 obj-y                   += fault_$(BITS).o
 obj-y                   += init_$(BITS).o
 obj-$(CONFIG_SPARC32)   += extable.o srmmu.o iommu.o io-unit.o
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
deleted file mode 100644
index 1e770a517d4a..000000000000
--- a/arch/sparc/mm/gup.c
+++ /dev/null
@@ -1,340 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for sparc, cribbed from powerpc
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- */
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/pagemap.h>
-#include <linux/rwsem.h>
-#include <asm/pgtable.h>
-#include <asm/adi.h>
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long mask, result;
-	pte_t *ptep;
-
-	if (tlb_type = hypervisor) {
-		result = _PAGE_PRESENT_4V|_PAGE_P_4V;
-		if (write)
-			result |= _PAGE_WRITE_4V;
-	} else {
-		result = _PAGE_PRESENT_4U|_PAGE_P_4U;
-		if (write)
-			result |= _PAGE_WRITE_4U;
-	}
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_kernel(&pmd, addr);
-	do {
-		struct page *page, *head;
-		pte_t pte = *ptep;
-
-		if ((pte_val(pte) & mask) != result)
-			return 0;
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-		/* The hugepage case is simplified on sparc64 because
-		 * we encode the sub-page pfn offsets into the
-		 * hugepage PTEs.  We could optimize this in the future
-		 * use page_cache_add_speculative() for the hugepage case.
-		 */
-		page = pte_page(pte);
-		head = compound_head(page);
-		if (!page_cache_get_speculative(head))
-			return 0;
-		if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-			put_page(head);
-			return 0;
-		}
-
-		pages[*nr] = page;
-		(*nr)++;
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pmd_val(pmd) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pmd_write(pmd))
-		return 0;
-
-	refs = 0;
-	page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pud_val(pud) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pud_write(pud))
-		return 0;
-
-	refs = 0;
-	page = pud_page(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pud_val(pud) != pud_val(*pudp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_large(pmd))) {
-			if (!gup_huge_pmd(pmdp, pmd, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pte_range(pmd, addr, next, write,
-					  pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_large(pud))) {
-			if (!gup_huge_pud(pudp, pud, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next, flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implement version tags.
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implements version tags,
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch size
-	 * will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables from being freed on sparc.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the the page and take a ref on it.
-	 */
-	local_irq_disable();
-
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

Re: [PATCH 10/16] sparc64: use the generic get_user_pages_fast code

[Hillf Danton]

Hi Christoph 

On Sat,  1 Jun 2019 09:49:53 +0200 Christoph Hellwig wrote:
> 
> diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> index a93eca29e85a..2301ab5250e4 100644
> --- a/arch/sparc/include/asm/pgtable_64.h
> +++ b/arch/sparc/include/asm/pgtable_64.h
> @@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
>  }
>  #define untagged_addr untagged_addr
>  
> +static inline bool pte_access_permitted(pte_t pte, bool write)
> +{
> +	u64 prot;
> +
> +	if (tlb_type == hypervisor) {
> +		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
> +		if (prot)

Feel free to correct me if I misread or miss anything.
It looks like a typo: s/prot/write/, as checking _PAGE_PRESENT_4V and
_PAGE_P_4V makes prot always have _PAGE_WRITE_4V set, regardless of write.

> +			prot |= _PAGE_WRITE_4V;
> +	} else {
> +		prot = _PAGE_PRESENT_4U | _PAGE_P_4U;
> +		if (write)
> +			prot |= _PAGE_WRITE_4U;
> +	}
> +
> +	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot;
> +}
> +#define pte_access_permitted pte_access_permitted
> +
>  #include <asm/tlbflush.h>
>  #include <asm-generic/pgtable.h>

BR
Hillf

[PATCH 10/16] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sparc64 code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/Kconfig                  |   1 +
 arch/sparc/include/asm/pgtable_64.h |  18 ++
 arch/sparc/mm/Makefile              |   2 +-
 arch/sparc/mm/gup.c                 | 340 ----------------------------
 4 files changed, 20 insertions(+), 341 deletions(-)
 delete mode 100644 arch/sparc/mm/gup.c

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 26ab6f5bbaaf..22435471f942 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,6 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
+	select HAVE_GENERIC_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index a93eca29e85a..2301ab5250e4 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
 }
 #define untagged_addr untagged_addr
 
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot;
+
+	if (tlb_type == hypervisor) {
+		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
+		if (prot)
+			prot |= _PAGE_WRITE_4V;
+	} else {
+		prot = _PAGE_PRESENT_4U | _PAGE_P_4U;
+		if (write)
+			prot |= _PAGE_WRITE_4U;
+	}
+
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot;
+}
+#define pte_access_permitted pte_access_permitted
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
diff --git a/arch/sparc/mm/Makefile b/arch/sparc/mm/Makefile
index d39075b1e3b7..b078205b70e0 100644
--- a/arch/sparc/mm/Makefile
+++ b/arch/sparc/mm/Makefile
@@ -5,7 +5,7 @@
 asflags-y := -ansi
 ccflags-y := -Werror
 
-obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o gup.o
+obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o
 obj-y                   += fault_$(BITS).o
 obj-y                   += init_$(BITS).o
 obj-$(CONFIG_SPARC32)   += extable.o srmmu.o iommu.o io-unit.o
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
deleted file mode 100644
index 1e770a517d4a..000000000000
--- a/arch/sparc/mm/gup.c
+++ /dev/null
@@ -1,340 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for sparc, cribbed from powerpc
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- */
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/pagemap.h>
-#include <linux/rwsem.h>
-#include <asm/pgtable.h>
-#include <asm/adi.h>
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long mask, result;
-	pte_t *ptep;
-
-	if (tlb_type == hypervisor) {
-		result = _PAGE_PRESENT_4V|_PAGE_P_4V;
-		if (write)
-			result |= _PAGE_WRITE_4V;
-	} else {
-		result = _PAGE_PRESENT_4U|_PAGE_P_4U;
-		if (write)
-			result |= _PAGE_WRITE_4U;
-	}
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_kernel(&pmd, addr);
-	do {
-		struct page *page, *head;
-		pte_t pte = *ptep;
-
-		if ((pte_val(pte) & mask) != result)
-			return 0;
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-		/* The hugepage case is simplified on sparc64 because
-		 * we encode the sub-page pfn offsets into the
-		 * hugepage PTEs.  We could optimize this in the future
-		 * use page_cache_add_speculative() for the hugepage case.
-		 */
-		page = pte_page(pte);
-		head = compound_head(page);
-		if (!page_cache_get_speculative(head))
-			return 0;
-		if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-			put_page(head);
-			return 0;
-		}
-
-		pages[*nr] = page;
-		(*nr)++;
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pmd_val(pmd) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pmd_write(pmd))
-		return 0;
-
-	refs = 0;
-	page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pud_val(pud) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pud_write(pud))
-		return 0;
-
-	refs = 0;
-	page = pud_page(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pud_val(pud) != pud_val(*pudp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_large(pmd))) {
-			if (!gup_huge_pmd(pmdp, pmd, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pte_range(pmd, addr, next, write,
-					  pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_large(pud))) {
-			if (!gup_huge_pud(pudp, pud, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next, flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implement version tags.
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implements version tags,
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch size
-	 * will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables from being freed on sparc.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the the page and take a ref on it.
-	 */
-	local_irq_disable();
-
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

[PATCH 10/16] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

The sparc64 code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/Kconfig                  |   1 +
 arch/sparc/include/asm/pgtable_64.h |  18 ++
 arch/sparc/mm/Makefile              |   2 +-
 arch/sparc/mm/gup.c                 | 340 ----------------------------
 4 files changed, 20 insertions(+), 341 deletions(-)
 delete mode 100644 arch/sparc/mm/gup.c

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 26ab6f5bbaaf..22435471f942 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,6 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
+	select HAVE_GENERIC_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index a93eca29e85a..2301ab5250e4 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
 }
 #define untagged_addr untagged_addr
 
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	u64 prot;
+
+	if (tlb_type == hypervisor) {
+		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
+		if (prot)
+			prot |= _PAGE_WRITE_4V;
+	} else {
+		prot = _PAGE_PRESENT_4U | _PAGE_P_4U;
+		if (write)
+			prot |= _PAGE_WRITE_4U;
+	}
+
+	return (pte_val(pte) & (prot | _PAGE_SPECIAL)) == prot;
+}
+#define pte_access_permitted pte_access_permitted
+
 #include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
diff --git a/arch/sparc/mm/Makefile b/arch/sparc/mm/Makefile
index d39075b1e3b7..b078205b70e0 100644
--- a/arch/sparc/mm/Makefile
+++ b/arch/sparc/mm/Makefile
@@ -5,7 +5,7 @@
 asflags-y := -ansi
 ccflags-y := -Werror
 
-obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o gup.o
+obj-$(CONFIG_SPARC64)   += ultra.o tlb.o tsb.o
 obj-y                   += fault_$(BITS).o
 obj-y                   += init_$(BITS).o
 obj-$(CONFIG_SPARC32)   += extable.o srmmu.o iommu.o io-unit.o
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
deleted file mode 100644
index 1e770a517d4a..000000000000
--- a/arch/sparc/mm/gup.c
+++ /dev/null
@@ -1,340 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Lockless get_user_pages_fast for sparc, cribbed from powerpc
- *
- * Copyright (C) 2008 Nick Piggin
- * Copyright (C) 2008 Novell Inc.
- */
-
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/vmstat.h>
-#include <linux/pagemap.h>
-#include <linux/rwsem.h>
-#include <asm/pgtable.h>
-#include <asm/adi.h>
-
-/*
- * The performance critical leaf functions are made noinline otherwise gcc
- * inlines everything into a single function which results in too much
- * register pressure.
- */
-static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long mask, result;
-	pte_t *ptep;
-
-	if (tlb_type == hypervisor) {
-		result = _PAGE_PRESENT_4V|_PAGE_P_4V;
-		if (write)
-			result |= _PAGE_WRITE_4V;
-	} else {
-		result = _PAGE_PRESENT_4U|_PAGE_P_4U;
-		if (write)
-			result |= _PAGE_WRITE_4U;
-	}
-	mask = result | _PAGE_SPECIAL;
-
-	ptep = pte_offset_kernel(&pmd, addr);
-	do {
-		struct page *page, *head;
-		pte_t pte = *ptep;
-
-		if ((pte_val(pte) & mask) != result)
-			return 0;
-		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-		/* The hugepage case is simplified on sparc64 because
-		 * we encode the sub-page pfn offsets into the
-		 * hugepage PTEs.  We could optimize this in the future
-		 * use page_cache_add_speculative() for the hugepage case.
-		 */
-		page = pte_page(pte);
-		head = compound_head(page);
-		if (!page_cache_get_speculative(head))
-			return 0;
-		if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-			put_page(head);
-			return 0;
-		}
-
-		pages[*nr] = page;
-		(*nr)++;
-	} while (ptep++, addr += PAGE_SIZE, addr != end);
-
-	return 1;
-}
-
-static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pmd_val(pmd) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pmd_write(pmd))
-		return 0;
-
-	refs = 0;
-	page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,
-			unsigned long end, int write, struct page **pages,
-			int *nr)
-{
-	struct page *head, *page;
-	int refs;
-
-	if (!(pud_val(pud) & _PAGE_VALID))
-		return 0;
-
-	if (write && !pud_write(pud))
-		return 0;
-
-	refs = 0;
-	page = pud_page(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	head = compound_head(page);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pud_val(pud) != pud_val(*pudp))) {
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pmd_t *pmdp;
-
-	pmdp = pmd_offset(&pud, addr);
-	do {
-		pmd_t pmd = *pmdp;
-
-		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
-			return 0;
-		if (unlikely(pmd_large(pmd))) {
-			if (!gup_huge_pmd(pmdp, pmd, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pte_range(pmd, addr, next, write,
-					  pages, nr))
-			return 0;
-	} while (pmdp++, addr = next, addr != end);
-
-	return 1;
-}
-
-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
-		int write, struct page **pages, int *nr)
-{
-	unsigned long next;
-	pud_t *pudp;
-
-	pudp = pud_offset(&pgd, addr);
-	do {
-		pud_t pud = *pudp;
-
-		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
-			return 0;
-		if (unlikely(pud_large(pud))) {
-			if (!gup_huge_pud(pudp, pud, addr, next,
-					  write, pages, nr))
-				return 0;
-		} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
-			return 0;
-	} while (pudp++, addr = next, addr != end);
-
-	return 1;
-}
-
-/*
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
-			  struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next, flags;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implement version tags.
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	local_irq_save(flags);
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			break;
-		if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
-			break;
-	} while (pgdp++, addr = next, addr != end);
-	local_irq_restore(flags);
-
-	return nr;
-}
-
-int get_user_pages_fast(unsigned long start, int nr_pages,
-			unsigned int gup_flags, struct page **pages)
-{
-	struct mm_struct *mm = current->mm;
-	unsigned long addr, len, end;
-	unsigned long next;
-	pgd_t *pgdp;
-	int nr = 0;
-
-#ifdef CONFIG_SPARC64
-	if (adi_capable()) {
-		long addr = start;
-
-		/* If userspace has passed a versioned address, kernel
-		 * will not find it in the VMAs since it does not store
-		 * the version tags in the list of VMAs. Storing version
-		 * tags in list of VMAs is impractical since they can be
-		 * changed any time from userspace without dropping into
-		 * kernel. Any address search in VMAs will be done with
-		 * non-versioned addresses. Ensure the ADI version bits
-		 * are dropped here by sign extending the last bit before
-		 * ADI bits. IOMMU does not implements version tags,
-		 */
-		addr = (addr << (long)adi_nbits()) >> (long)adi_nbits();
-		start = addr;
-	}
-#endif
-	start &= PAGE_MASK;
-	addr = start;
-	len = (unsigned long) nr_pages << PAGE_SHIFT;
-	end = start + len;
-
-	/*
-	 * XXX: batch / limit 'nr', to avoid large irq off latency
-	 * needs some instrumenting to determine the common sizes used by
-	 * important workloads (eg. DB2), and whether limiting the batch size
-	 * will decrease performance.
-	 *
-	 * It seems like we're in the clear for the moment. Direct-IO is
-	 * the main guy that batches up lots of get_user_pages, and even
-	 * they are limited to 64-at-a-time which is not so many.
-	 */
-	/*
-	 * This doesn't prevent pagetable teardown, but does prevent
-	 * the pagetables from being freed on sparc.
-	 *
-	 * So long as we atomically load page table pointers versus teardown,
-	 * we can follow the address down to the the page and take a ref on it.
-	 */
-	local_irq_disable();
-
-	pgdp = pgd_offset(mm, addr);
-	do {
-		pgd_t pgd = *pgdp;
-
-		next = pgd_addr_end(addr, end);
-		if (pgd_none(pgd))
-			goto slow;
-		if (!gup_pud_range(pgd, addr, next, gup_flags & FOLL_WRITE,
-				   pages, &nr))
-			goto slow;
-	} while (pgdp++, addr = next, addr != end);
-
-	local_irq_enable();
-
-	VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-	return nr;
-
-	{
-		int ret;
-
-slow:
-		local_irq_enable();
-
-		/* Try to get the remaining pages with get_user_pages */
-		start += nr << PAGE_SHIFT;
-		pages += nr;
-
-		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, pages,
-			gup_flags);
-
-		/* Have to be a bit careful with return values */
-		if (nr > 0) {
-			if (ret < 0)
-				ret = nr;
-			else
-				ret += nr;
-		}
-
-		return ret;
-	}
-}
-- 
2.20.1

Re: [PATCH 10/16] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

On Sun, Jun 02, 2019 at 03:39:48PM +0800, Hillf Danton wrote:
> 
> Hi Christoph 
> 
> On Sat,  1 Jun 2019 09:49:53 +0200 Christoph Hellwig wrote:
> > 
> > diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> > index a93eca29e85a..2301ab5250e4 100644
> > --- a/arch/sparc/include/asm/pgtable_64.h
> > +++ b/arch/sparc/include/asm/pgtable_64.h
> > @@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
> >  }
> >  #define untagged_addr untagged_addr
> >  
> > +static inline bool pte_access_permitted(pte_t pte, bool write)
> > +{
> > +	u64 prot;
> > +
> > +	if (tlb_type = hypervisor) {
> > +		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
> > +		if (prot)
> 
> Feel free to correct me if I misread or miss anything.
> It looks like a typo: s/prot/write/, as checking _PAGE_PRESENT_4V and
> _PAGE_P_4V makes prot always have _PAGE_WRITE_4V set, regardless of write.

True, the if prot should be if write.

Re: [PATCH 10/16] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

On Sun, Jun 02, 2019 at 03:39:48PM +0800, Hillf Danton wrote:
> 
> Hi Christoph 
> 
> On Sat,  1 Jun 2019 09:49:53 +0200 Christoph Hellwig wrote:
> > 
> > diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> > index a93eca29e85a..2301ab5250e4 100644
> > --- a/arch/sparc/include/asm/pgtable_64.h
> > +++ b/arch/sparc/include/asm/pgtable_64.h
> > @@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
> >  }
> >  #define untagged_addr untagged_addr
> >  
> > +static inline bool pte_access_permitted(pte_t pte, bool write)
> > +{
> > +	u64 prot;
> > +
> > +	if (tlb_type == hypervisor) {
> > +		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
> > +		if (prot)
> 
> Feel free to correct me if I misread or miss anything.
> It looks like a typo: s/prot/write/, as checking _PAGE_PRESENT_4V and
> _PAGE_P_4V makes prot always have _PAGE_WRITE_4V set, regardless of write.

True, the if prot should be if write.

Re: [PATCH 10/16] sparc64: use the generic get_user_pages_fast code

[Christoph Hellwig]

On Sun, Jun 02, 2019 at 03:39:48PM +0800, Hillf Danton wrote:
> 
> Hi Christoph 
> 
> On Sat,  1 Jun 2019 09:49:53 +0200 Christoph Hellwig wrote:
> > 
> > diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> > index a93eca29e85a..2301ab5250e4 100644
> > --- a/arch/sparc/include/asm/pgtable_64.h
> > +++ b/arch/sparc/include/asm/pgtable_64.h
> > @@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
> >  }
> >  #define untagged_addr untagged_addr
> >  
> > +static inline bool pte_access_permitted(pte_t pte, bool write)
> > +{
> > +	u64 prot;
> > +
> > +	if (tlb_type == hypervisor) {
> > +		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
> > +		if (prot)
> 
> Feel free to correct me if I misread or miss anything.
> It looks like a typo: s/prot/write/, as checking _PAGE_PRESENT_4V and
> _PAGE_P_4V makes prot always have _PAGE_WRITE_4V set, regardless of write.

True, the if prot should be if write.

[PATCH 11/16] mm: rename CONFIG_HAVE_GENERIC_GUP to CONFIG_HAVE_FAST_GUP

[Christoph Hellwig]

We only support the generic GUP now, so rename the config option to
be more clear, and always use the mm/Kconfig definition of the
symbol and select it from the arch Kconfigs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/Kconfig     | 5 +----
 arch/arm64/Kconfig   | 4 +---
 arch/mips/Kconfig    | 2 +-
 arch/powerpc/Kconfig | 2 +-
 arch/s390/Kconfig    | 2 +-
 arch/sh/Kconfig      | 2 +-
 arch/sparc/Kconfig   | 2 +-
 arch/x86/Kconfig     | 4 +---
 mm/Kconfig           | 2 +-
 mm/gup.c             | 4 ++--
 10 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8869742a85df..3879a3e2c511 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -73,6 +73,7 @@ config ARM
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP if ARM_LPAE
 	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
 	select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG
 	select HAVE_FUNCTION_TRACER if !XIP_KERNEL
@@ -1596,10 +1597,6 @@ config ARCH_SELECT_MEMORY_MODEL
 config HAVE_ARCH_PFN_VALID
 	def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM
 
-config HAVE_GENERIC_GUP
-	def_bool y
-	depends on ARM_LPAE
-
 config HIGHMEM
 	bool "High Memory Support"
 	depends on MMU
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 697ea0510729..4a6ee3e92757 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -140,6 +140,7 @@ config ARM64
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
@@ -262,9 +263,6 @@ config GENERIC_CALIBRATE_DELAY
 config ZONE_DMA32
 	def_bool y
 
-config HAVE_GENERIC_GUP
-	def_bool y
-
 config ARCH_ENABLE_MEMORY_HOTPLUG
 	def_bool y
 
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 64108a2a16d4..b1e42f0e4ed0 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -54,10 +54,10 @@ config MIPS
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
-	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8c1c636308c8..992a04796e56 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -185,12 +185,12 @@ config PPC
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS	if MPROFILE_KERNEL
 	select HAVE_EBPF_JIT			if PPC64
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS	if !(CPU_LITTLE_ENDIAN && POWER7_CPU)
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
 	select HAVE_GCC_PLUGINS			if GCC_VERSION >= 50200   # plugin support on gcc <= 5.1 is buggy on PPC
-	select HAVE_GENERIC_GUP
 	select HAVE_HW_BREAKPOINT		if PERF_EVENTS && (PPC_BOOK3S || PPC_8xx)
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 109243fdb6ec..aaff0376bf53 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -137,6 +137,7 @@ config S390
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
+	select HAVE_FAST_GUP
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_FENTRY
 	select HAVE_FTRACE_MCOUNT_RECORD
@@ -144,7 +145,6 @@ config S390
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_GCC_PLUGINS
-	select HAVE_GENERIC_GUP
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZ4
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 6fddfc3c9710..56712f3c9838 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,7 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
-	select HAVE_GENERIC_GUP
+	select HAVE_FAST_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 22435471f942..659232b760e1 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,7 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
-	select HAVE_GENERIC_GUP if SPARC64
+	select HAVE_FAST_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7cd53cc59f0f..44500e0ed630 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -157,6 +157,7 @@ config X86
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_EISA
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP
 	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
@@ -2874,9 +2875,6 @@ config HAVE_ATOMIC_IOMAP
 config X86_DEV_DMA_OPS
 	bool
 
-config HAVE_GENERIC_GUP
-	def_bool y
-
 source "drivers/firmware/Kconfig"
 
 source "arch/x86/kvm/Kconfig"
diff --git a/mm/Kconfig b/mm/Kconfig
index fe51f104a9e0..98dffb0f2447 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -132,7 +132,7 @@ config HAVE_MEMBLOCK_NODE_MAP
 config HAVE_MEMBLOCK_PHYS_MAP
 	bool
 
-config HAVE_GENERIC_GUP
+config HAVE_FAST_GUP
 	bool
 
 config ARCH_KEEP_MEMBLOCK
diff --git a/mm/gup.c b/mm/gup.c
index a86d65cd7051..a24f52292c7f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1650,7 +1650,7 @@ struct page *get_dump_page(unsigned long addr)
 #endif /* CONFIG_ELF_CORE */
 
 /*
- * Generic Fast GUP
+ * Fast GUP
  *
  * get_user_pages_fast attempts to pin user pages by walking the page
  * tables directly and avoids taking locks. Thus the walker needs to be
@@ -1682,7 +1682,7 @@ struct page *get_dump_page(unsigned long addr)
  *
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
-#ifdef CONFIG_HAVE_GENERIC_GUP
+#ifdef CONFIG_HAVE_FAST_GUP
 #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
 /*
  * WARNING: only to be used in the get_user_pages_fast() implementation.
-- 
2.20.1

[PATCH 11/16] mm: rename CONFIG_HAVE_GENERIC_GUP to CONFIG_HAVE_FAST_GUP

[Christoph Hellwig]

We only support the generic GUP now, so rename the config option to
be more clear, and always use the mm/Kconfig definition of the
symbol and select it from the arch Kconfigs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/Kconfig     | 5 +----
 arch/arm64/Kconfig   | 4 +---
 arch/mips/Kconfig    | 2 +-
 arch/powerpc/Kconfig | 2 +-
 arch/s390/Kconfig    | 2 +-
 arch/sh/Kconfig      | 2 +-
 arch/sparc/Kconfig   | 2 +-
 arch/x86/Kconfig     | 4 +---
 mm/Kconfig           | 2 +-
 mm/gup.c             | 4 ++--
 10 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8869742a85df..3879a3e2c511 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -73,6 +73,7 @@ config ARM
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP if ARM_LPAE
 	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
 	select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG
 	select HAVE_FUNCTION_TRACER if !XIP_KERNEL
@@ -1596,10 +1597,6 @@ config ARCH_SELECT_MEMORY_MODEL
 config HAVE_ARCH_PFN_VALID
 	def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM
 
-config HAVE_GENERIC_GUP
-	def_bool y
-	depends on ARM_LPAE
-
 config HIGHMEM
 	bool "High Memory Support"
 	depends on MMU
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 697ea0510729..4a6ee3e92757 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -140,6 +140,7 @@ config ARM64
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
@@ -262,9 +263,6 @@ config GENERIC_CALIBRATE_DELAY
 config ZONE_DMA32
 	def_bool y
 
-config HAVE_GENERIC_GUP
-	def_bool y
-
 config ARCH_ENABLE_MEMORY_HOTPLUG
 	def_bool y
 
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 64108a2a16d4..b1e42f0e4ed0 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -54,10 +54,10 @@ config MIPS
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
-	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8c1c636308c8..992a04796e56 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -185,12 +185,12 @@ config PPC
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS	if MPROFILE_KERNEL
 	select HAVE_EBPF_JIT			if PPC64
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS	if !(CPU_LITTLE_ENDIAN && POWER7_CPU)
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
 	select HAVE_GCC_PLUGINS			if GCC_VERSION >= 50200   # plugin support on gcc <= 5.1 is buggy on PPC
-	select HAVE_GENERIC_GUP
 	select HAVE_HW_BREAKPOINT		if PERF_EVENTS && (PPC_BOOK3S || PPC_8xx)
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 109243fdb6ec..aaff0376bf53 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -137,6 +137,7 @@ config S390
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
+	select HAVE_FAST_GUP
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_FENTRY
 	select HAVE_FTRACE_MCOUNT_RECORD
@@ -144,7 +145,6 @@ config S390
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_GCC_PLUGINS
-	select HAVE_GENERIC_GUP
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZ4
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 6fddfc3c9710..56712f3c9838 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,7 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
-	select HAVE_GENERIC_GUP
+	select HAVE_FAST_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 22435471f942..659232b760e1 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,7 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
-	select HAVE_GENERIC_GUP if SPARC64
+	select HAVE_FAST_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7cd53cc59f0f..44500e0ed630 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -157,6 +157,7 @@ config X86
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_EISA
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP
 	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
@@ -2874,9 +2875,6 @@ config HAVE_ATOMIC_IOMAP
 config X86_DEV_DMA_OPS
 	bool
 
-config HAVE_GENERIC_GUP
-	def_bool y
-
 source "drivers/firmware/Kconfig"
 
 source "arch/x86/kvm/Kconfig"
diff --git a/mm/Kconfig b/mm/Kconfig
index fe51f104a9e0..98dffb0f2447 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -132,7 +132,7 @@ config HAVE_MEMBLOCK_NODE_MAP
 config HAVE_MEMBLOCK_PHYS_MAP
 	bool
 
-config HAVE_GENERIC_GUP
+config HAVE_FAST_GUP
 	bool
 
 config ARCH_KEEP_MEMBLOCK
diff --git a/mm/gup.c b/mm/gup.c
index a86d65cd7051..a24f52292c7f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1650,7 +1650,7 @@ struct page *get_dump_page(unsigned long addr)
 #endif /* CONFIG_ELF_CORE */
 
 /*
- * Generic Fast GUP
+ * Fast GUP
  *
  * get_user_pages_fast attempts to pin user pages by walking the page
  * tables directly and avoids taking locks. Thus the walker needs to be
@@ -1682,7 +1682,7 @@ struct page *get_dump_page(unsigned long addr)
  *
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
-#ifdef CONFIG_HAVE_GENERIC_GUP
+#ifdef CONFIG_HAVE_FAST_GUP
 #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
 /*
  * WARNING: only to be used in the get_user_pages_fast() implementation.
-- 
2.20.1

[PATCH 11/16] mm: rename CONFIG_HAVE_GENERIC_GUP to CONFIG_HAVE_FAST_GUP

[Christoph Hellwig]

We only support the generic GUP now, so rename the config option to
be more clear, and always use the mm/Kconfig definition of the
symbol and select it from the arch Kconfigs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/Kconfig     | 5 +----
 arch/arm64/Kconfig   | 4 +---
 arch/mips/Kconfig    | 2 +-
 arch/powerpc/Kconfig | 2 +-
 arch/s390/Kconfig    | 2 +-
 arch/sh/Kconfig      | 2 +-
 arch/sparc/Kconfig   | 2 +-
 arch/x86/Kconfig     | 4 +---
 mm/Kconfig           | 2 +-
 mm/gup.c             | 4 ++--
 10 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8869742a85df..3879a3e2c511 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -73,6 +73,7 @@ config ARM
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP if ARM_LPAE
 	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
 	select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG
 	select HAVE_FUNCTION_TRACER if !XIP_KERNEL
@@ -1596,10 +1597,6 @@ config ARCH_SELECT_MEMORY_MODEL
 config HAVE_ARCH_PFN_VALID
 	def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM
 
-config HAVE_GENERIC_GUP
-	def_bool y
-	depends on ARM_LPAE
-
 config HIGHMEM
 	bool "High Memory Support"
 	depends on MMU
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 697ea0510729..4a6ee3e92757 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -140,6 +140,7 @@ config ARM64
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
@@ -262,9 +263,6 @@ config GENERIC_CALIBRATE_DELAY
 config ZONE_DMA32
 	def_bool y
 
-config HAVE_GENERIC_GUP
-	def_bool y
-
 config ARCH_ENABLE_MEMORY_HOTPLUG
 	def_bool y
 
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 64108a2a16d4..b1e42f0e4ed0 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -54,10 +54,10 @@ config MIPS
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
-	select HAVE_GENERIC_GUP
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8c1c636308c8..992a04796e56 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -185,12 +185,12 @@ config PPC
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS	if MPROFILE_KERNEL
 	select HAVE_EBPF_JIT			if PPC64
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS	if !(CPU_LITTLE_ENDIAN && POWER7_CPU)
+	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
 	select HAVE_GCC_PLUGINS			if GCC_VERSION >= 50200   # plugin support on gcc <= 5.1 is buggy on PPC
-	select HAVE_GENERIC_GUP
 	select HAVE_HW_BREAKPOINT		if PERF_EVENTS && (PPC_BOOK3S || PPC_8xx)
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 109243fdb6ec..aaff0376bf53 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -137,6 +137,7 @@ config S390
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
+	select HAVE_FAST_GUP
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_FENTRY
 	select HAVE_FTRACE_MCOUNT_RECORD
@@ -144,7 +145,6 @@ config S390
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_GCC_PLUGINS
-	select HAVE_GENERIC_GUP
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZ4
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 6fddfc3c9710..56712f3c9838 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,7 +14,7 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
-	select HAVE_GENERIC_GUP
+	select HAVE_FAST_GUP
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 22435471f942..659232b760e1 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -28,7 +28,7 @@ config SPARC
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
-	select HAVE_GENERIC_GUP if SPARC64
+	select HAVE_FAST_GUP if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7cd53cc59f0f..44500e0ed630 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -157,6 +157,7 @@ config X86
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_EISA
 	select HAVE_EXIT_THREAD
+	select HAVE_FAST_GUP
 	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
@@ -2874,9 +2875,6 @@ config HAVE_ATOMIC_IOMAP
 config X86_DEV_DMA_OPS
 	bool
 
-config HAVE_GENERIC_GUP
-	def_bool y
-
 source "drivers/firmware/Kconfig"
 
 source "arch/x86/kvm/Kconfig"
diff --git a/mm/Kconfig b/mm/Kconfig
index fe51f104a9e0..98dffb0f2447 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -132,7 +132,7 @@ config HAVE_MEMBLOCK_NODE_MAP
 config HAVE_MEMBLOCK_PHYS_MAP
 	bool
 
-config HAVE_GENERIC_GUP
+config HAVE_FAST_GUP
 	bool
 
 config ARCH_KEEP_MEMBLOCK
diff --git a/mm/gup.c b/mm/gup.c
index a86d65cd7051..a24f52292c7f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1650,7 +1650,7 @@ struct page *get_dump_page(unsigned long addr)
 #endif /* CONFIG_ELF_CORE */
 
 /*
- * Generic Fast GUP
+ * Fast GUP
  *
  * get_user_pages_fast attempts to pin user pages by walking the page
  * tables directly and avoids taking locks. Thus the walker needs to be
@@ -1682,7 +1682,7 @@ struct page *get_dump_page(unsigned long addr)
  *
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
-#ifdef CONFIG_HAVE_GENERIC_GUP
+#ifdef CONFIG_HAVE_FAST_GUP
 #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
 /*
  * WARNING: only to be used in the get_user_pages_fast() implementation.
-- 
2.20.1

[PATCH 12/16] mm: consolidate the get_user_pages* implementations

[Christoph Hellwig]

Always build mm/gup.c, and move the nommu versions and replace the
separate stubs for various functions by the default ones, with the _fast
version always falling back to the slow path because gup_fast_permitted
always returns false now if HAVE_FAST_GUP is not set, and we use the
nommu version of __get_user_pages while keeping all the wrappers common.

This also ensures the new put_user_pages* helpers are available for
nommu, as those are currently missing, which would create a problem as
soon as we actually grew users for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/Kconfig  |   1 +
 mm/Makefile |   4 +-
 mm/gup.c    | 476 +++++++++++++++++++++++++++++-----------------------
 mm/nommu.c  |  88 ----------
 mm/util.c   |  47 ------
 5 files changed, 269 insertions(+), 347 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 98dffb0f2447..5c41409557da 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -133,6 +133,7 @@ config HAVE_MEMBLOCK_PHYS_MAP
 	bool
 
 config HAVE_FAST_GUP
+	depends on MMU
 	bool
 
 config ARCH_KEEP_MEMBLOCK
diff --git a/mm/Makefile b/mm/Makefile
index ac5e5ba78874..dc0746ca1109 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -22,7 +22,7 @@ KCOV_INSTRUMENT_mmzone.o := n
 KCOV_INSTRUMENT_vmstat.o := n
 
 mmu-y			:= nommu.o
-mmu-$(CONFIG_MMU)	:= gup.o highmem.o memory.o mincore.o \
+mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
 			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
 			   msync.o page_vma_mapped.o pagewalk.o \
 			   pgtable-generic.o rmap.o vmalloc.o
@@ -39,7 +39,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
 			   mm_init.o mmu_context.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   debug.o $(mmu-y)
+			   debug.o gup.o $(mmu-y)
 
 # Give 'page_alloc' its own module-parameter namespace
 page-alloc-y := page_alloc.o
diff --git a/mm/gup.c b/mm/gup.c
index a24f52292c7f..c8da7764de9c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -134,6 +134,7 @@ void put_user_pages(struct page **pages, unsigned long npages)
 }
 EXPORT_SYMBOL(put_user_pages);
 
+#ifdef CONFIG_MMU
 static struct page *no_page_table(struct vm_area_struct *vma,
 		unsigned int flags)
 {
@@ -1099,86 +1100,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 	return pages_done;
 }
 
-/*
- * We can leverage the VM_FAULT_RETRY functionality in the page fault
- * paths better by using either get_user_pages_locked() or
- * get_user_pages_unlocked().
- *
- * get_user_pages_locked() is suitable to replace the form:
- *
- *      down_read(&mm->mmap_sem);
- *      do_something()
- *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
- *
- *  to:
- *
- *      int locked = 1;
- *      down_read(&mm->mmap_sem);
- *      do_something()
- *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
- *      if (locked)
- *          up_read(&mm->mmap_sem);
- */
-long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			   unsigned int gup_flags, struct page **pages,
-			   int *locked)
-{
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-
-	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, NULL, locked,
-				       gup_flags | FOLL_TOUCH);
-}
-EXPORT_SYMBOL(get_user_pages_locked);
-
-/*
- * get_user_pages_unlocked() is suitable to replace the form:
- *
- *      down_read(&mm->mmap_sem);
- *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
- *
- *  with:
- *
- *      get_user_pages_unlocked(tsk, mm, ..., pages);
- *
- * It is functionally equivalent to get_user_pages_fast so
- * get_user_pages_fast should be used instead if specific gup_flags
- * (e.g. FOLL_FORCE) are not required.
- */
-long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     struct page **pages, unsigned int gup_flags)
-{
-	struct mm_struct *mm = current->mm;
-	int locked = 1;
-	long ret;
-
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-
-	down_read(&mm->mmap_sem);
-	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
-				      &locked, gup_flags | FOLL_TOUCH);
-	if (locked)
-		up_read(&mm->mmap_sem);
-	return ret;
-}
-EXPORT_SYMBOL(get_user_pages_unlocked);
-
 /*
  * get_user_pages_remote() - pin user pages in memory
  * @tsk:	the task_struct to use for page fault accounting, or
@@ -1255,6 +1176,199 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
+/**
+ * populate_vma_page_range() -  populate a range of pages in the vma.
+ * @vma:   target vma
+ * @start: start address
+ * @end:   end address
+ * @nonblocking:
+ *
+ * This takes care of mlocking the pages too if VM_LOCKED is set.
+ *
+ * return 0 on success, negative error code on error.
+ *
+ * vma->vm_mm->mmap_sem must be held.
+ *
+ * If @nonblocking is NULL, it may be held for read or write and will
+ * be unperturbed.
+ *
+ * If @nonblocking is non-NULL, it must held for read only and may be
+ * released.  If it's released, *@nonblocking will be set to 0.
+ */
+long populate_vma_page_range(struct vm_area_struct *vma,
+		unsigned long start, unsigned long end, int *nonblocking)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long nr_pages = (end - start) / PAGE_SIZE;
+	int gup_flags;
+
+	VM_BUG_ON(start & ~PAGE_MASK);
+	VM_BUG_ON(end   & ~PAGE_MASK);
+	VM_BUG_ON_VMA(start < vma->vm_start, vma);
+	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+
+	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
+	if (vma->vm_flags & VM_LOCKONFAULT)
+		gup_flags &= ~FOLL_POPULATE;
+	/*
+	 * We want to touch writable mappings with a write fault in order
+	 * to break COW, except for shared mappings because these don't COW
+	 * and we would not want to dirty them for nothing.
+	 */
+	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) = VM_WRITE)
+		gup_flags |= FOLL_WRITE;
+
+	/*
+	 * We want mlock to succeed for regions that have any permissions
+	 * other than PROT_NONE.
+	 */
+	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
+		gup_flags |= FOLL_FORCE;
+
+	/*
+	 * We made sure addr is within a VMA, so the following will
+	 * not result in a stack expansion that recurses back here.
+	 */
+	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
+				NULL, NULL, nonblocking);
+}
+
+/*
+ * __mm_populate - populate and/or mlock pages within a range of address space.
+ *
+ * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
+ * flags. VMAs must be already marked with the desired vm_flags, and
+ * mmap_sem must not be held.
+ */
+int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long end, nstart, nend;
+	struct vm_area_struct *vma = NULL;
+	int locked = 0;
+	long ret = 0;
+
+	end = start + len;
+
+	for (nstart = start; nstart < end; nstart = nend) {
+		/*
+		 * We want to fault in pages for [nstart; end) address range.
+		 * Find first corresponding VMA.
+		 */
+		if (!locked) {
+			locked = 1;
+			down_read(&mm->mmap_sem);
+			vma = find_vma(mm, nstart);
+		} else if (nstart >= vma->vm_end)
+			vma = vma->vm_next;
+		if (!vma || vma->vm_start >= end)
+			break;
+		/*
+		 * Set [nstart; nend) to intersection of desired address
+		 * range with the first VMA. Also, skip undesirable VMA types.
+		 */
+		nend = min(end, vma->vm_end);
+		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
+			continue;
+		if (nstart < vma->vm_start)
+			nstart = vma->vm_start;
+		/*
+		 * Now fault in a range of pages. populate_vma_page_range()
+		 * double checks the vma flags, so that it won't mlock pages
+		 * if the vma was already munlocked.
+		 */
+		ret = populate_vma_page_range(vma, nstart, nend, &locked);
+		if (ret < 0) {
+			if (ignore_errors) {
+				ret = 0;
+				continue;	/* continue at next VMA */
+			}
+			break;
+		}
+		nend = nstart + ret * PAGE_SIZE;
+		ret = 0;
+	}
+	if (locked)
+		up_read(&mm->mmap_sem);
+	return ret;	/* 0 or negative error code */
+}
+
+/**
+ * get_dump_page() - pin user page in memory while writing it to core dump
+ * @addr: user address
+ *
+ * Returns struct page pointer of user page pinned for dump,
+ * to be freed afterwards by put_page().
+ *
+ * Returns NULL on any kind of failure - a hole must then be inserted into
+ * the corefile, to preserve alignment with its headers; and also returns
+ * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
+ * allowing a hole to be left in the corefile to save diskspace.
+ *
+ * Called without mmap_sem, but after all other threads have been killed.
+ */
+#ifdef CONFIG_ELF_CORE
+struct page *get_dump_page(unsigned long addr)
+{
+	struct vm_area_struct *vma;
+	struct page *page;
+
+	if (__get_user_pages(current, current->mm, addr, 1,
+			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
+			     NULL) < 1)
+		return NULL;
+	flush_cache_page(vma, addr, page_to_pfn(page));
+	return page;
+}
+#endif /* CONFIG_ELF_CORE */
+
+#else /* CONFIG_MMU */
+static long __get_user_pages_locked(struct task_struct *tsk,
+		struct mm_struct *mm, unsigned long start,
+		unsigned long nr_pages, struct page **pages,
+		struct vm_area_struct **vmas, int *locked,
+		unsigned int foll_flags)
+{
+	struct vm_area_struct *vma;
+	unsigned long vm_flags;
+	int i;
+
+	/* calculate required read or write permissions.
+	 * If FOLL_FORCE is set, we only require the "MAY" flags.
+	 */
+	vm_flags  = (foll_flags & FOLL_WRITE) ?
+			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
+	vm_flags &= (foll_flags & FOLL_FORCE) ?
+			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
+
+	for (i = 0; i < nr_pages; i++) {
+		vma = find_vma(mm, start);
+		if (!vma)
+			goto finish_or_fault;
+
+		/* protect what we can, including chardevs */
+		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
+		    !(vm_flags & vma->vm_flags))
+			goto finish_or_fault;
+
+		if (pages) {
+			pages[i] = virt_to_page(start);
+			if (pages[i])
+				get_page(pages[i]);
+		}
+		if (vmas)
+			vmas[i] = vma;
+		start = (start + PAGE_SIZE) & PAGE_MASK;
+	}
+
+	return i;
+
+finish_or_fault:
+	return i ? : -EFAULT;
+}
+#endif /* !CONFIG_MMU */
+
 #if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
 static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
 {
@@ -1416,7 +1530,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
 {
 	return nr_pages;
 }
-#endif
+#endif /* CONFIG_CMA */
 
 /*
  * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
@@ -1502,152 +1616,85 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 }
 EXPORT_SYMBOL(get_user_pages);
 
-/**
- * populate_vma_page_range() -  populate a range of pages in the vma.
- * @vma:   target vma
- * @start: start address
- * @end:   end address
- * @nonblocking:
- *
- * This takes care of mlocking the pages too if VM_LOCKED is set.
+/*
+ * We can leverage the VM_FAULT_RETRY functionality in the page fault
+ * paths better by using either get_user_pages_locked() or
+ * get_user_pages_unlocked().
  *
- * return 0 on success, negative error code on error.
+ * get_user_pages_locked() is suitable to replace the form:
  *
- * vma->vm_mm->mmap_sem must be held.
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
  *
- * If @nonblocking is NULL, it may be held for read or write and will
- * be unperturbed.
+ *  to:
  *
- * If @nonblocking is non-NULL, it must held for read only and may be
- * released.  If it's released, *@nonblocking will be set to 0.
+ *      int locked = 1;
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
+ *      if (locked)
+ *          up_read(&mm->mmap_sem);
  */
-long populate_vma_page_range(struct vm_area_struct *vma,
-		unsigned long start, unsigned long end, int *nonblocking)
+long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
+			   unsigned int gup_flags, struct page **pages,
+			   int *locked)
 {
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long nr_pages = (end - start) / PAGE_SIZE;
-	int gup_flags;
-
-	VM_BUG_ON(start & ~PAGE_MASK);
-	VM_BUG_ON(end   & ~PAGE_MASK);
-	VM_BUG_ON_VMA(start < vma->vm_start, vma);
-	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
-
-	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
-	if (vma->vm_flags & VM_LOCKONFAULT)
-		gup_flags &= ~FOLL_POPULATE;
-	/*
-	 * We want to touch writable mappings with a write fault in order
-	 * to break COW, except for shared mappings because these don't COW
-	 * and we would not want to dirty them for nothing.
-	 */
-	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) = VM_WRITE)
-		gup_flags |= FOLL_WRITE;
-
 	/*
-	 * We want mlock to succeed for regions that have any permissions
-	 * other than PROT_NONE.
+	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
+	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
+	 * vmas.  As there are no users of this flag in this call we simply
+	 * disallow this option for now.
 	 */
-	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
-		gup_flags |= FOLL_FORCE;
+	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+		return -EINVAL;
 
-	/*
-	 * We made sure addr is within a VMA, so the following will
-	 * not result in a stack expansion that recurses back here.
-	 */
-	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
-				NULL, NULL, nonblocking);
+	return __get_user_pages_locked(current, current->mm, start, nr_pages,
+				       pages, NULL, locked,
+				       gup_flags | FOLL_TOUCH);
 }
+EXPORT_SYMBOL(get_user_pages_locked);
 
 /*
- * __mm_populate - populate and/or mlock pages within a range of address space.
+ * get_user_pages_unlocked() is suitable to replace the form:
  *
- * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
- * flags. VMAs must be already marked with the desired vm_flags, and
- * mmap_sem must not be held.
+ *      down_read(&mm->mmap_sem);
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
+ *
+ *  with:
+ *
+ *      get_user_pages_unlocked(tsk, mm, ..., pages);
+ *
+ * It is functionally equivalent to get_user_pages_fast so
+ * get_user_pages_fast should be used instead if specific gup_flags
+ * (e.g. FOLL_FORCE) are not required.
  */
-int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
+long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
+			     struct page **pages, unsigned int gup_flags)
 {
 	struct mm_struct *mm = current->mm;
-	unsigned long end, nstart, nend;
-	struct vm_area_struct *vma = NULL;
-	int locked = 0;
-	long ret = 0;
+	int locked = 1;
+	long ret;
 
-	end = start + len;
+	/*
+	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
+	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
+	 * vmas.  As there are no users of this flag in this call we simply
+	 * disallow this option for now.
+	 */
+	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+		return -EINVAL;
 
-	for (nstart = start; nstart < end; nstart = nend) {
-		/*
-		 * We want to fault in pages for [nstart; end) address range.
-		 * Find first corresponding VMA.
-		 */
-		if (!locked) {
-			locked = 1;
-			down_read(&mm->mmap_sem);
-			vma = find_vma(mm, nstart);
-		} else if (nstart >= vma->vm_end)
-			vma = vma->vm_next;
-		if (!vma || vma->vm_start >= end)
-			break;
-		/*
-		 * Set [nstart; nend) to intersection of desired address
-		 * range with the first VMA. Also, skip undesirable VMA types.
-		 */
-		nend = min(end, vma->vm_end);
-		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
-			continue;
-		if (nstart < vma->vm_start)
-			nstart = vma->vm_start;
-		/*
-		 * Now fault in a range of pages. populate_vma_page_range()
-		 * double checks the vma flags, so that it won't mlock pages
-		 * if the vma was already munlocked.
-		 */
-		ret = populate_vma_page_range(vma, nstart, nend, &locked);
-		if (ret < 0) {
-			if (ignore_errors) {
-				ret = 0;
-				continue;	/* continue at next VMA */
-			}
-			break;
-		}
-		nend = nstart + ret * PAGE_SIZE;
-		ret = 0;
-	}
+	down_read(&mm->mmap_sem);
+	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
+				      &locked, gup_flags | FOLL_TOUCH);
 	if (locked)
 		up_read(&mm->mmap_sem);
-	return ret;	/* 0 or negative error code */
-}
-
-/**
- * get_dump_page() - pin user page in memory while writing it to core dump
- * @addr: user address
- *
- * Returns struct page pointer of user page pinned for dump,
- * to be freed afterwards by put_page().
- *
- * Returns NULL on any kind of failure - a hole must then be inserted into
- * the corefile, to preserve alignment with its headers; and also returns
- * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
- * allowing a hole to be left in the corefile to save diskspace.
- *
- * Called without mmap_sem, but after all other threads have been killed.
- */
-#ifdef CONFIG_ELF_CORE
-struct page *get_dump_page(unsigned long addr)
-{
-	struct vm_area_struct *vma;
-	struct page *page;
-
-	if (__get_user_pages(current, current->mm, addr, 1,
-			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
-			     NULL) < 1)
-		return NULL;
-	flush_cache_page(vma, addr, page_to_pfn(page));
-	return page;
+	return ret;
 }
-#endif /* CONFIG_ELF_CORE */
+EXPORT_SYMBOL(get_user_pages_unlocked);
 
 /*
  * Fast GUP
@@ -1682,7 +1729,7 @@ struct page *get_dump_page(unsigned long addr)
  *
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
-#ifdef CONFIG_HAVE_FAST_GUP
+#if defined(CONFIG_MMU) && defined(CONFIG_HAVE_FAST_GUP)
 #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
 /*
  * WARNING: only to be used in the get_user_pages_fast() implementation.
@@ -2159,6 +2206,12 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
 			return;
 	} while (pgdp++, addr = next, addr != end);
 }
+#else
+static inline void gup_pgd_range(unsigned long addr, unsigned long end,
+		unsigned int flags, struct page **pages, int *nr)
+{
+}
+#endif /* CONFIG_HAVE_FAST_GUP */
 
 #ifndef gup_fast_permitted
 /*
@@ -2167,7 +2220,7 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
  */
 static bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	return true;
+	return IS_ENABLED(CONFIG_HAVE_FAST_GUP) ? true : false;
 }
 #endif
 
@@ -2176,6 +2229,9 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
  * the regular GUP.
  * Note a difference with get_user_pages_fast: this always returns the
  * number of pages pinned, 0 if no pages were pinned.
+ *
+ * If the architecture does not support this function, simply return with no
+ * pages pinned.
  */
 int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			  struct page **pages)
@@ -2213,6 +2269,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 
 	return nr;
 }
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);
 
 static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
 				   unsigned int gup_flags, struct page **pages)
@@ -2295,5 +2352,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 
 	return ret;
 }
-
-#endif /* CONFIG_HAVE_GENERIC_GUP */
+EXPORT_SYMBOL_GPL(get_user_pages_fast);
diff --git a/mm/nommu.c b/mm/nommu.c
index d8c02fbe03b5..07165ad2e548 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -111,94 +111,6 @@ unsigned int kobjsize(const void *objp)
 	return PAGE_SIZE << compound_order(page);
 }
 
-static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-		      unsigned long start, unsigned long nr_pages,
-		      unsigned int foll_flags, struct page **pages,
-		      struct vm_area_struct **vmas, int *nonblocking)
-{
-	struct vm_area_struct *vma;
-	unsigned long vm_flags;
-	int i;
-
-	/* calculate required read or write permissions.
-	 * If FOLL_FORCE is set, we only require the "MAY" flags.
-	 */
-	vm_flags  = (foll_flags & FOLL_WRITE) ?
-			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
-	vm_flags &= (foll_flags & FOLL_FORCE) ?
-			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
-
-	for (i = 0; i < nr_pages; i++) {
-		vma = find_vma(mm, start);
-		if (!vma)
-			goto finish_or_fault;
-
-		/* protect what we can, including chardevs */
-		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
-		    !(vm_flags & vma->vm_flags))
-			goto finish_or_fault;
-
-		if (pages) {
-			pages[i] = virt_to_page(start);
-			if (pages[i])
-				get_page(pages[i]);
-		}
-		if (vmas)
-			vmas[i] = vma;
-		start = (start + PAGE_SIZE) & PAGE_MASK;
-	}
-
-	return i;
-
-finish_or_fault:
-	return i ? : -EFAULT;
-}
-
-/*
- * get a list of pages in an address range belonging to the specified process
- * and indicate the VMA that covers each page
- * - this is potentially dodgy as we may end incrementing the page count of a
- *   slab page or a secondary page from a compound page
- * - don't permit access to VMAs that don't support it, such as I/O mappings
- */
-long get_user_pages(unsigned long start, unsigned long nr_pages,
-		    unsigned int gup_flags, struct page **pages,
-		    struct vm_area_struct **vmas)
-{
-	return __get_user_pages(current, current->mm, start, nr_pages,
-				gup_flags, pages, vmas, NULL);
-}
-EXPORT_SYMBOL(get_user_pages);
-
-long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			    unsigned int gup_flags, struct page **pages,
-			    int *locked)
-{
-	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
-}
-EXPORT_SYMBOL(get_user_pages_locked);
-
-static long __get_user_pages_unlocked(struct task_struct *tsk,
-			struct mm_struct *mm, unsigned long start,
-			unsigned long nr_pages, struct page **pages,
-			unsigned int gup_flags)
-{
-	long ret;
-	down_read(&mm->mmap_sem);
-	ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
-				NULL, NULL);
-	up_read(&mm->mmap_sem);
-	return ret;
-}
-
-long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     struct page **pages, unsigned int gup_flags)
-{
-	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 pages, gup_flags);
-}
-EXPORT_SYMBOL(get_user_pages_unlocked);
-
 /**
  * follow_pfn - look up PFN at a user virtual address
  * @vma: memory mapping
diff --git a/mm/util.c b/mm/util.c
index 91682a2090ee..d58f5b0eb669 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -300,53 +300,6 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 }
 #endif
 
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- * If the architecture does not support this function, simply return with no
- * pages pinned.
- */
-int __weak __get_user_pages_fast(unsigned long start,
-				 int nr_pages, int write, struct page **pages)
-{
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__get_user_pages_fast);
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * get_user_pages_fast provides equivalent functionality to get_user_pages,
- * operating on current and current->mm, with force=0 and vma=NULL. However
- * unlike get_user_pages, it must be called without mmap_sem held.
- *
- * get_user_pages_fast may take mmap_sem and page table locks, so no
- * assumptions can be made about lack of locking. get_user_pages_fast is to be
- * implemented in a way that is advantageous (vs get_user_pages()) when the
- * user memory area is already faulted in and present in ptes. However if the
- * pages have to be faulted in, it may turn out to be slightly slower so
- * callers need to carefully consider what to use. On many architectures,
- * get_user_pages_fast simply falls back to get_user_pages.
- *
- * Return: number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int __weak get_user_pages_fast(unsigned long start,
-				int nr_pages, unsigned int gup_flags,
-				struct page **pages)
-{
-	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
-}
-EXPORT_SYMBOL_GPL(get_user_pages_fast);
-
 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,
 	unsigned long flag, unsigned long pgoff)
-- 
2.20.1

[PATCH 12/16] mm: consolidate the get_user_pages* implementations

[Christoph Hellwig]

Always build mm/gup.c, and move the nommu versions and replace the
separate stubs for various functions by the default ones, with the _fast
version always falling back to the slow path because gup_fast_permitted
always returns false now if HAVE_FAST_GUP is not set, and we use the
nommu version of __get_user_pages while keeping all the wrappers common.

This also ensures the new put_user_pages* helpers are available for
nommu, as those are currently missing, which would create a problem as
soon as we actually grew users for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/Kconfig  |   1 +
 mm/Makefile |   4 +-
 mm/gup.c    | 476 +++++++++++++++++++++++++++++-----------------------
 mm/nommu.c  |  88 ----------
 mm/util.c   |  47 ------
 5 files changed, 269 insertions(+), 347 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 98dffb0f2447..5c41409557da 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -133,6 +133,7 @@ config HAVE_MEMBLOCK_PHYS_MAP
 	bool
 
 config HAVE_FAST_GUP
+	depends on MMU
 	bool
 
 config ARCH_KEEP_MEMBLOCK
diff --git a/mm/Makefile b/mm/Makefile
index ac5e5ba78874..dc0746ca1109 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -22,7 +22,7 @@ KCOV_INSTRUMENT_mmzone.o := n
 KCOV_INSTRUMENT_vmstat.o := n
 
 mmu-y			:= nommu.o
-mmu-$(CONFIG_MMU)	:= gup.o highmem.o memory.o mincore.o \
+mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
 			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
 			   msync.o page_vma_mapped.o pagewalk.o \
 			   pgtable-generic.o rmap.o vmalloc.o
@@ -39,7 +39,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
 			   mm_init.o mmu_context.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   debug.o $(mmu-y)
+			   debug.o gup.o $(mmu-y)
 
 # Give 'page_alloc' its own module-parameter namespace
 page-alloc-y := page_alloc.o
diff --git a/mm/gup.c b/mm/gup.c
index a24f52292c7f..c8da7764de9c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -134,6 +134,7 @@ void put_user_pages(struct page **pages, unsigned long npages)
 }
 EXPORT_SYMBOL(put_user_pages);
 
+#ifdef CONFIG_MMU
 static struct page *no_page_table(struct vm_area_struct *vma,
 		unsigned int flags)
 {
@@ -1099,86 +1100,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 	return pages_done;
 }
 
-/*
- * We can leverage the VM_FAULT_RETRY functionality in the page fault
- * paths better by using either get_user_pages_locked() or
- * get_user_pages_unlocked().
- *
- * get_user_pages_locked() is suitable to replace the form:
- *
- *      down_read(&mm->mmap_sem);
- *      do_something()
- *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
- *
- *  to:
- *
- *      int locked = 1;
- *      down_read(&mm->mmap_sem);
- *      do_something()
- *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
- *      if (locked)
- *          up_read(&mm->mmap_sem);
- */
-long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			   unsigned int gup_flags, struct page **pages,
-			   int *locked)
-{
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-
-	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, NULL, locked,
-				       gup_flags | FOLL_TOUCH);
-}
-EXPORT_SYMBOL(get_user_pages_locked);
-
-/*
- * get_user_pages_unlocked() is suitable to replace the form:
- *
- *      down_read(&mm->mmap_sem);
- *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
- *
- *  with:
- *
- *      get_user_pages_unlocked(tsk, mm, ..., pages);
- *
- * It is functionally equivalent to get_user_pages_fast so
- * get_user_pages_fast should be used instead if specific gup_flags
- * (e.g. FOLL_FORCE) are not required.
- */
-long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     struct page **pages, unsigned int gup_flags)
-{
-	struct mm_struct *mm = current->mm;
-	int locked = 1;
-	long ret;
-
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-
-	down_read(&mm->mmap_sem);
-	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
-				      &locked, gup_flags | FOLL_TOUCH);
-	if (locked)
-		up_read(&mm->mmap_sem);
-	return ret;
-}
-EXPORT_SYMBOL(get_user_pages_unlocked);
-
 /*
  * get_user_pages_remote() - pin user pages in memory
  * @tsk:	the task_struct to use for page fault accounting, or
@@ -1255,6 +1176,199 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
+/**
+ * populate_vma_page_range() -  populate a range of pages in the vma.
+ * @vma:   target vma
+ * @start: start address
+ * @end:   end address
+ * @nonblocking:
+ *
+ * This takes care of mlocking the pages too if VM_LOCKED is set.
+ *
+ * return 0 on success, negative error code on error.
+ *
+ * vma->vm_mm->mmap_sem must be held.
+ *
+ * If @nonblocking is NULL, it may be held for read or write and will
+ * be unperturbed.
+ *
+ * If @nonblocking is non-NULL, it must held for read only and may be
+ * released.  If it's released, *@nonblocking will be set to 0.
+ */
+long populate_vma_page_range(struct vm_area_struct *vma,
+		unsigned long start, unsigned long end, int *nonblocking)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long nr_pages = (end - start) / PAGE_SIZE;
+	int gup_flags;
+
+	VM_BUG_ON(start & ~PAGE_MASK);
+	VM_BUG_ON(end   & ~PAGE_MASK);
+	VM_BUG_ON_VMA(start < vma->vm_start, vma);
+	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+
+	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
+	if (vma->vm_flags & VM_LOCKONFAULT)
+		gup_flags &= ~FOLL_POPULATE;
+	/*
+	 * We want to touch writable mappings with a write fault in order
+	 * to break COW, except for shared mappings because these don't COW
+	 * and we would not want to dirty them for nothing.
+	 */
+	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
+		gup_flags |= FOLL_WRITE;
+
+	/*
+	 * We want mlock to succeed for regions that have any permissions
+	 * other than PROT_NONE.
+	 */
+	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
+		gup_flags |= FOLL_FORCE;
+
+	/*
+	 * We made sure addr is within a VMA, so the following will
+	 * not result in a stack expansion that recurses back here.
+	 */
+	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
+				NULL, NULL, nonblocking);
+}
+
+/*
+ * __mm_populate - populate and/or mlock pages within a range of address space.
+ *
+ * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
+ * flags. VMAs must be already marked with the desired vm_flags, and
+ * mmap_sem must not be held.
+ */
+int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long end, nstart, nend;
+	struct vm_area_struct *vma = NULL;
+	int locked = 0;
+	long ret = 0;
+
+	end = start + len;
+
+	for (nstart = start; nstart < end; nstart = nend) {
+		/*
+		 * We want to fault in pages for [nstart; end) address range.
+		 * Find first corresponding VMA.
+		 */
+		if (!locked) {
+			locked = 1;
+			down_read(&mm->mmap_sem);
+			vma = find_vma(mm, nstart);
+		} else if (nstart >= vma->vm_end)
+			vma = vma->vm_next;
+		if (!vma || vma->vm_start >= end)
+			break;
+		/*
+		 * Set [nstart; nend) to intersection of desired address
+		 * range with the first VMA. Also, skip undesirable VMA types.
+		 */
+		nend = min(end, vma->vm_end);
+		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
+			continue;
+		if (nstart < vma->vm_start)
+			nstart = vma->vm_start;
+		/*
+		 * Now fault in a range of pages. populate_vma_page_range()
+		 * double checks the vma flags, so that it won't mlock pages
+		 * if the vma was already munlocked.
+		 */
+		ret = populate_vma_page_range(vma, nstart, nend, &locked);
+		if (ret < 0) {
+			if (ignore_errors) {
+				ret = 0;
+				continue;	/* continue at next VMA */
+			}
+			break;
+		}
+		nend = nstart + ret * PAGE_SIZE;
+		ret = 0;
+	}
+	if (locked)
+		up_read(&mm->mmap_sem);
+	return ret;	/* 0 or negative error code */
+}
+
+/**
+ * get_dump_page() - pin user page in memory while writing it to core dump
+ * @addr: user address
+ *
+ * Returns struct page pointer of user page pinned for dump,
+ * to be freed afterwards by put_page().
+ *
+ * Returns NULL on any kind of failure - a hole must then be inserted into
+ * the corefile, to preserve alignment with its headers; and also returns
+ * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
+ * allowing a hole to be left in the corefile to save diskspace.
+ *
+ * Called without mmap_sem, but after all other threads have been killed.
+ */
+#ifdef CONFIG_ELF_CORE
+struct page *get_dump_page(unsigned long addr)
+{
+	struct vm_area_struct *vma;
+	struct page *page;
+
+	if (__get_user_pages(current, current->mm, addr, 1,
+			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
+			     NULL) < 1)
+		return NULL;
+	flush_cache_page(vma, addr, page_to_pfn(page));
+	return page;
+}
+#endif /* CONFIG_ELF_CORE */
+
+#else /* CONFIG_MMU */
+static long __get_user_pages_locked(struct task_struct *tsk,
+		struct mm_struct *mm, unsigned long start,
+		unsigned long nr_pages, struct page **pages,
+		struct vm_area_struct **vmas, int *locked,
+		unsigned int foll_flags)
+{
+	struct vm_area_struct *vma;
+	unsigned long vm_flags;
+	int i;
+
+	/* calculate required read or write permissions.
+	 * If FOLL_FORCE is set, we only require the "MAY" flags.
+	 */
+	vm_flags  = (foll_flags & FOLL_WRITE) ?
+			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
+	vm_flags &= (foll_flags & FOLL_FORCE) ?
+			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
+
+	for (i = 0; i < nr_pages; i++) {
+		vma = find_vma(mm, start);
+		if (!vma)
+			goto finish_or_fault;
+
+		/* protect what we can, including chardevs */
+		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
+		    !(vm_flags & vma->vm_flags))
+			goto finish_or_fault;
+
+		if (pages) {
+			pages[i] = virt_to_page(start);
+			if (pages[i])
+				get_page(pages[i]);
+		}
+		if (vmas)
+			vmas[i] = vma;
+		start = (start + PAGE_SIZE) & PAGE_MASK;
+	}
+
+	return i;
+
+finish_or_fault:
+	return i ? : -EFAULT;
+}
+#endif /* !CONFIG_MMU */
+
 #if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
 static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
 {
@@ -1416,7 +1530,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
 {
 	return nr_pages;
 }
-#endif
+#endif /* CONFIG_CMA */
 
 /*
  * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
@@ -1502,152 +1616,85 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 }
 EXPORT_SYMBOL(get_user_pages);
 
-/**
- * populate_vma_page_range() -  populate a range of pages in the vma.
- * @vma:   target vma
- * @start: start address
- * @end:   end address
- * @nonblocking:
- *
- * This takes care of mlocking the pages too if VM_LOCKED is set.
+/*
+ * We can leverage the VM_FAULT_RETRY functionality in the page fault
+ * paths better by using either get_user_pages_locked() or
+ * get_user_pages_unlocked().
  *
- * return 0 on success, negative error code on error.
+ * get_user_pages_locked() is suitable to replace the form:
  *
- * vma->vm_mm->mmap_sem must be held.
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
  *
- * If @nonblocking is NULL, it may be held for read or write and will
- * be unperturbed.
+ *  to:
  *
- * If @nonblocking is non-NULL, it must held for read only and may be
- * released.  If it's released, *@nonblocking will be set to 0.
+ *      int locked = 1;
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
+ *      if (locked)
+ *          up_read(&mm->mmap_sem);
  */
-long populate_vma_page_range(struct vm_area_struct *vma,
-		unsigned long start, unsigned long end, int *nonblocking)
+long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
+			   unsigned int gup_flags, struct page **pages,
+			   int *locked)
 {
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long nr_pages = (end - start) / PAGE_SIZE;
-	int gup_flags;
-
-	VM_BUG_ON(start & ~PAGE_MASK);
-	VM_BUG_ON(end   & ~PAGE_MASK);
-	VM_BUG_ON_VMA(start < vma->vm_start, vma);
-	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
-
-	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
-	if (vma->vm_flags & VM_LOCKONFAULT)
-		gup_flags &= ~FOLL_POPULATE;
-	/*
-	 * We want to touch writable mappings with a write fault in order
-	 * to break COW, except for shared mappings because these don't COW
-	 * and we would not want to dirty them for nothing.
-	 */
-	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
-		gup_flags |= FOLL_WRITE;
-
 	/*
-	 * We want mlock to succeed for regions that have any permissions
-	 * other than PROT_NONE.
+	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
+	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
+	 * vmas.  As there are no users of this flag in this call we simply
+	 * disallow this option for now.
 	 */
-	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
-		gup_flags |= FOLL_FORCE;
+	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+		return -EINVAL;
 
-	/*
-	 * We made sure addr is within a VMA, so the following will
-	 * not result in a stack expansion that recurses back here.
-	 */
-	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
-				NULL, NULL, nonblocking);
+	return __get_user_pages_locked(current, current->mm, start, nr_pages,
+				       pages, NULL, locked,
+				       gup_flags | FOLL_TOUCH);
 }
+EXPORT_SYMBOL(get_user_pages_locked);
 
 /*
- * __mm_populate - populate and/or mlock pages within a range of address space.
+ * get_user_pages_unlocked() is suitable to replace the form:
  *
- * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
- * flags. VMAs must be already marked with the desired vm_flags, and
- * mmap_sem must not be held.
+ *      down_read(&mm->mmap_sem);
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
+ *
+ *  with:
+ *
+ *      get_user_pages_unlocked(tsk, mm, ..., pages);
+ *
+ * It is functionally equivalent to get_user_pages_fast so
+ * get_user_pages_fast should be used instead if specific gup_flags
+ * (e.g. FOLL_FORCE) are not required.
  */
-int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
+long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
+			     struct page **pages, unsigned int gup_flags)
 {
 	struct mm_struct *mm = current->mm;
-	unsigned long end, nstart, nend;
-	struct vm_area_struct *vma = NULL;
-	int locked = 0;
-	long ret = 0;
+	int locked = 1;
+	long ret;
 
-	end = start + len;
+	/*
+	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
+	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
+	 * vmas.  As there are no users of this flag in this call we simply
+	 * disallow this option for now.
+	 */
+	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+		return -EINVAL;
 
-	for (nstart = start; nstart < end; nstart = nend) {
-		/*
-		 * We want to fault in pages for [nstart; end) address range.
-		 * Find first corresponding VMA.
-		 */
-		if (!locked) {
-			locked = 1;
-			down_read(&mm->mmap_sem);
-			vma = find_vma(mm, nstart);
-		} else if (nstart >= vma->vm_end)
-			vma = vma->vm_next;
-		if (!vma || vma->vm_start >= end)
-			break;
-		/*
-		 * Set [nstart; nend) to intersection of desired address
-		 * range with the first VMA. Also, skip undesirable VMA types.
-		 */
-		nend = min(end, vma->vm_end);
-		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
-			continue;
-		if (nstart < vma->vm_start)
-			nstart = vma->vm_start;
-		/*
-		 * Now fault in a range of pages. populate_vma_page_range()
-		 * double checks the vma flags, so that it won't mlock pages
-		 * if the vma was already munlocked.
-		 */
-		ret = populate_vma_page_range(vma, nstart, nend, &locked);
-		if (ret < 0) {
-			if (ignore_errors) {
-				ret = 0;
-				continue;	/* continue at next VMA */
-			}
-			break;
-		}
-		nend = nstart + ret * PAGE_SIZE;
-		ret = 0;
-	}
+	down_read(&mm->mmap_sem);
+	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
+				      &locked, gup_flags | FOLL_TOUCH);
 	if (locked)
 		up_read(&mm->mmap_sem);
-	return ret;	/* 0 or negative error code */
-}
-
-/**
- * get_dump_page() - pin user page in memory while writing it to core dump
- * @addr: user address
- *
- * Returns struct page pointer of user page pinned for dump,
- * to be freed afterwards by put_page().
- *
- * Returns NULL on any kind of failure - a hole must then be inserted into
- * the corefile, to preserve alignment with its headers; and also returns
- * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
- * allowing a hole to be left in the corefile to save diskspace.
- *
- * Called without mmap_sem, but after all other threads have been killed.
- */
-#ifdef CONFIG_ELF_CORE
-struct page *get_dump_page(unsigned long addr)
-{
-	struct vm_area_struct *vma;
-	struct page *page;
-
-	if (__get_user_pages(current, current->mm, addr, 1,
-			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
-			     NULL) < 1)
-		return NULL;
-	flush_cache_page(vma, addr, page_to_pfn(page));
-	return page;
+	return ret;
 }
-#endif /* CONFIG_ELF_CORE */
+EXPORT_SYMBOL(get_user_pages_unlocked);
 
 /*
  * Fast GUP
@@ -1682,7 +1729,7 @@ struct page *get_dump_page(unsigned long addr)
  *
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
-#ifdef CONFIG_HAVE_FAST_GUP
+#if defined(CONFIG_MMU) && defined(CONFIG_HAVE_FAST_GUP)
 #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
 /*
  * WARNING: only to be used in the get_user_pages_fast() implementation.
@@ -2159,6 +2206,12 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
 			return;
 	} while (pgdp++, addr = next, addr != end);
 }
+#else
+static inline void gup_pgd_range(unsigned long addr, unsigned long end,
+		unsigned int flags, struct page **pages, int *nr)
+{
+}
+#endif /* CONFIG_HAVE_FAST_GUP */
 
 #ifndef gup_fast_permitted
 /*
@@ -2167,7 +2220,7 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
  */
 static bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	return true;
+	return IS_ENABLED(CONFIG_HAVE_FAST_GUP) ? true : false;
 }
 #endif
 
@@ -2176,6 +2229,9 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
  * the regular GUP.
  * Note a difference with get_user_pages_fast: this always returns the
  * number of pages pinned, 0 if no pages were pinned.
+ *
+ * If the architecture does not support this function, simply return with no
+ * pages pinned.
  */
 int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			  struct page **pages)
@@ -2213,6 +2269,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 
 	return nr;
 }
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);
 
 static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
 				   unsigned int gup_flags, struct page **pages)
@@ -2295,5 +2352,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 
 	return ret;
 }
-
-#endif /* CONFIG_HAVE_GENERIC_GUP */
+EXPORT_SYMBOL_GPL(get_user_pages_fast);
diff --git a/mm/nommu.c b/mm/nommu.c
index d8c02fbe03b5..07165ad2e548 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -111,94 +111,6 @@ unsigned int kobjsize(const void *objp)
 	return PAGE_SIZE << compound_order(page);
 }
 
-static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-		      unsigned long start, unsigned long nr_pages,
-		      unsigned int foll_flags, struct page **pages,
-		      struct vm_area_struct **vmas, int *nonblocking)
-{
-	struct vm_area_struct *vma;
-	unsigned long vm_flags;
-	int i;
-
-	/* calculate required read or write permissions.
-	 * If FOLL_FORCE is set, we only require the "MAY" flags.
-	 */
-	vm_flags  = (foll_flags & FOLL_WRITE) ?
-			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
-	vm_flags &= (foll_flags & FOLL_FORCE) ?
-			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
-
-	for (i = 0; i < nr_pages; i++) {
-		vma = find_vma(mm, start);
-		if (!vma)
-			goto finish_or_fault;
-
-		/* protect what we can, including chardevs */
-		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
-		    !(vm_flags & vma->vm_flags))
-			goto finish_or_fault;
-
-		if (pages) {
-			pages[i] = virt_to_page(start);
-			if (pages[i])
-				get_page(pages[i]);
-		}
-		if (vmas)
-			vmas[i] = vma;
-		start = (start + PAGE_SIZE) & PAGE_MASK;
-	}
-
-	return i;
-
-finish_or_fault:
-	return i ? : -EFAULT;
-}
-
-/*
- * get a list of pages in an address range belonging to the specified process
- * and indicate the VMA that covers each page
- * - this is potentially dodgy as we may end incrementing the page count of a
- *   slab page or a secondary page from a compound page
- * - don't permit access to VMAs that don't support it, such as I/O mappings
- */
-long get_user_pages(unsigned long start, unsigned long nr_pages,
-		    unsigned int gup_flags, struct page **pages,
-		    struct vm_area_struct **vmas)
-{
-	return __get_user_pages(current, current->mm, start, nr_pages,
-				gup_flags, pages, vmas, NULL);
-}
-EXPORT_SYMBOL(get_user_pages);
-
-long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			    unsigned int gup_flags, struct page **pages,
-			    int *locked)
-{
-	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
-}
-EXPORT_SYMBOL(get_user_pages_locked);
-
-static long __get_user_pages_unlocked(struct task_struct *tsk,
-			struct mm_struct *mm, unsigned long start,
-			unsigned long nr_pages, struct page **pages,
-			unsigned int gup_flags)
-{
-	long ret;
-	down_read(&mm->mmap_sem);
-	ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
-				NULL, NULL);
-	up_read(&mm->mmap_sem);
-	return ret;
-}
-
-long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     struct page **pages, unsigned int gup_flags)
-{
-	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 pages, gup_flags);
-}
-EXPORT_SYMBOL(get_user_pages_unlocked);
-
 /**
  * follow_pfn - look up PFN at a user virtual address
  * @vma: memory mapping
diff --git a/mm/util.c b/mm/util.c
index 91682a2090ee..d58f5b0eb669 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -300,53 +300,6 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 }
 #endif
 
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- * If the architecture does not support this function, simply return with no
- * pages pinned.
- */
-int __weak __get_user_pages_fast(unsigned long start,
-				 int nr_pages, int write, struct page **pages)
-{
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__get_user_pages_fast);
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * get_user_pages_fast provides equivalent functionality to get_user_pages,
- * operating on current and current->mm, with force=0 and vma=NULL. However
- * unlike get_user_pages, it must be called without mmap_sem held.
- *
- * get_user_pages_fast may take mmap_sem and page table locks, so no
- * assumptions can be made about lack of locking. get_user_pages_fast is to be
- * implemented in a way that is advantageous (vs get_user_pages()) when the
- * user memory area is already faulted in and present in ptes. However if the
- * pages have to be faulted in, it may turn out to be slightly slower so
- * callers need to carefully consider what to use. On many architectures,
- * get_user_pages_fast simply falls back to get_user_pages.
- *
- * Return: number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int __weak get_user_pages_fast(unsigned long start,
-				int nr_pages, unsigned int gup_flags,
-				struct page **pages)
-{
-	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
-}
-EXPORT_SYMBOL_GPL(get_user_pages_fast);
-
 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,
 	unsigned long flag, unsigned long pgoff)
-- 
2.20.1

[PATCH 12/16] mm: consolidate the get_user_pages* implementations

[Christoph Hellwig]

Always build mm/gup.c, and move the nommu versions and replace the
separate stubs for various functions by the default ones, with the _fast
version always falling back to the slow path because gup_fast_permitted
always returns false now if HAVE_FAST_GUP is not set, and we use the
nommu version of __get_user_pages while keeping all the wrappers common.

This also ensures the new put_user_pages* helpers are available for
nommu, as those are currently missing, which would create a problem as
soon as we actually grew users for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/Kconfig  |   1 +
 mm/Makefile |   4 +-
 mm/gup.c    | 476 +++++++++++++++++++++++++++++-----------------------
 mm/nommu.c  |  88 ----------
 mm/util.c   |  47 ------
 5 files changed, 269 insertions(+), 347 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 98dffb0f2447..5c41409557da 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -133,6 +133,7 @@ config HAVE_MEMBLOCK_PHYS_MAP
 	bool
 
 config HAVE_FAST_GUP
+	depends on MMU
 	bool
 
 config ARCH_KEEP_MEMBLOCK
diff --git a/mm/Makefile b/mm/Makefile
index ac5e5ba78874..dc0746ca1109 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -22,7 +22,7 @@ KCOV_INSTRUMENT_mmzone.o := n
 KCOV_INSTRUMENT_vmstat.o := n
 
 mmu-y			:= nommu.o
-mmu-$(CONFIG_MMU)	:= gup.o highmem.o memory.o mincore.o \
+mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
 			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
 			   msync.o page_vma_mapped.o pagewalk.o \
 			   pgtable-generic.o rmap.o vmalloc.o
@@ -39,7 +39,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
 			   mm_init.o mmu_context.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   debug.o $(mmu-y)
+			   debug.o gup.o $(mmu-y)
 
 # Give 'page_alloc' its own module-parameter namespace
 page-alloc-y := page_alloc.o
diff --git a/mm/gup.c b/mm/gup.c
index a24f52292c7f..c8da7764de9c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -134,6 +134,7 @@ void put_user_pages(struct page **pages, unsigned long npages)
 }
 EXPORT_SYMBOL(put_user_pages);
 
+#ifdef CONFIG_MMU
 static struct page *no_page_table(struct vm_area_struct *vma,
 		unsigned int flags)
 {
@@ -1099,86 +1100,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 	return pages_done;
 }
 
-/*
- * We can leverage the VM_FAULT_RETRY functionality in the page fault
- * paths better by using either get_user_pages_locked() or
- * get_user_pages_unlocked().
- *
- * get_user_pages_locked() is suitable to replace the form:
- *
- *      down_read(&mm->mmap_sem);
- *      do_something()
- *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
- *
- *  to:
- *
- *      int locked = 1;
- *      down_read(&mm->mmap_sem);
- *      do_something()
- *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
- *      if (locked)
- *          up_read(&mm->mmap_sem);
- */
-long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			   unsigned int gup_flags, struct page **pages,
-			   int *locked)
-{
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-
-	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, NULL, locked,
-				       gup_flags | FOLL_TOUCH);
-}
-EXPORT_SYMBOL(get_user_pages_locked);
-
-/*
- * get_user_pages_unlocked() is suitable to replace the form:
- *
- *      down_read(&mm->mmap_sem);
- *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
- *
- *  with:
- *
- *      get_user_pages_unlocked(tsk, mm, ..., pages);
- *
- * It is functionally equivalent to get_user_pages_fast so
- * get_user_pages_fast should be used instead if specific gup_flags
- * (e.g. FOLL_FORCE) are not required.
- */
-long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     struct page **pages, unsigned int gup_flags)
-{
-	struct mm_struct *mm = current->mm;
-	int locked = 1;
-	long ret;
-
-	/*
-	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
-	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
-	 * vmas.  As there are no users of this flag in this call we simply
-	 * disallow this option for now.
-	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
-		return -EINVAL;
-
-	down_read(&mm->mmap_sem);
-	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
-				      &locked, gup_flags | FOLL_TOUCH);
-	if (locked)
-		up_read(&mm->mmap_sem);
-	return ret;
-}
-EXPORT_SYMBOL(get_user_pages_unlocked);
-
 /*
  * get_user_pages_remote() - pin user pages in memory
  * @tsk:	the task_struct to use for page fault accounting, or
@@ -1255,6 +1176,199 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
+/**
+ * populate_vma_page_range() -  populate a range of pages in the vma.
+ * @vma:   target vma
+ * @start: start address
+ * @end:   end address
+ * @nonblocking:
+ *
+ * This takes care of mlocking the pages too if VM_LOCKED is set.
+ *
+ * return 0 on success, negative error code on error.
+ *
+ * vma->vm_mm->mmap_sem must be held.
+ *
+ * If @nonblocking is NULL, it may be held for read or write and will
+ * be unperturbed.
+ *
+ * If @nonblocking is non-NULL, it must held for read only and may be
+ * released.  If it's released, *@nonblocking will be set to 0.
+ */
+long populate_vma_page_range(struct vm_area_struct *vma,
+		unsigned long start, unsigned long end, int *nonblocking)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long nr_pages = (end - start) / PAGE_SIZE;
+	int gup_flags;
+
+	VM_BUG_ON(start & ~PAGE_MASK);
+	VM_BUG_ON(end   & ~PAGE_MASK);
+	VM_BUG_ON_VMA(start < vma->vm_start, vma);
+	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+
+	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
+	if (vma->vm_flags & VM_LOCKONFAULT)
+		gup_flags &= ~FOLL_POPULATE;
+	/*
+	 * We want to touch writable mappings with a write fault in order
+	 * to break COW, except for shared mappings because these don't COW
+	 * and we would not want to dirty them for nothing.
+	 */
+	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
+		gup_flags |= FOLL_WRITE;
+
+	/*
+	 * We want mlock to succeed for regions that have any permissions
+	 * other than PROT_NONE.
+	 */
+	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
+		gup_flags |= FOLL_FORCE;
+
+	/*
+	 * We made sure addr is within a VMA, so the following will
+	 * not result in a stack expansion that recurses back here.
+	 */
+	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
+				NULL, NULL, nonblocking);
+}
+
+/*
+ * __mm_populate - populate and/or mlock pages within a range of address space.
+ *
+ * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
+ * flags. VMAs must be already marked with the desired vm_flags, and
+ * mmap_sem must not be held.
+ */
+int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long end, nstart, nend;
+	struct vm_area_struct *vma = NULL;
+	int locked = 0;
+	long ret = 0;
+
+	end = start + len;
+
+	for (nstart = start; nstart < end; nstart = nend) {
+		/*
+		 * We want to fault in pages for [nstart; end) address range.
+		 * Find first corresponding VMA.
+		 */
+		if (!locked) {
+			locked = 1;
+			down_read(&mm->mmap_sem);
+			vma = find_vma(mm, nstart);
+		} else if (nstart >= vma->vm_end)
+			vma = vma->vm_next;
+		if (!vma || vma->vm_start >= end)
+			break;
+		/*
+		 * Set [nstart; nend) to intersection of desired address
+		 * range with the first VMA. Also, skip undesirable VMA types.
+		 */
+		nend = min(end, vma->vm_end);
+		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
+			continue;
+		if (nstart < vma->vm_start)
+			nstart = vma->vm_start;
+		/*
+		 * Now fault in a range of pages. populate_vma_page_range()
+		 * double checks the vma flags, so that it won't mlock pages
+		 * if the vma was already munlocked.
+		 */
+		ret = populate_vma_page_range(vma, nstart, nend, &locked);
+		if (ret < 0) {
+			if (ignore_errors) {
+				ret = 0;
+				continue;	/* continue at next VMA */
+			}
+			break;
+		}
+		nend = nstart + ret * PAGE_SIZE;
+		ret = 0;
+	}
+	if (locked)
+		up_read(&mm->mmap_sem);
+	return ret;	/* 0 or negative error code */
+}
+
+/**
+ * get_dump_page() - pin user page in memory while writing it to core dump
+ * @addr: user address
+ *
+ * Returns struct page pointer of user page pinned for dump,
+ * to be freed afterwards by put_page().
+ *
+ * Returns NULL on any kind of failure - a hole must then be inserted into
+ * the corefile, to preserve alignment with its headers; and also returns
+ * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
+ * allowing a hole to be left in the corefile to save diskspace.
+ *
+ * Called without mmap_sem, but after all other threads have been killed.
+ */
+#ifdef CONFIG_ELF_CORE
+struct page *get_dump_page(unsigned long addr)
+{
+	struct vm_area_struct *vma;
+	struct page *page;
+
+	if (__get_user_pages(current, current->mm, addr, 1,
+			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
+			     NULL) < 1)
+		return NULL;
+	flush_cache_page(vma, addr, page_to_pfn(page));
+	return page;
+}
+#endif /* CONFIG_ELF_CORE */
+
+#else /* CONFIG_MMU */
+static long __get_user_pages_locked(struct task_struct *tsk,
+		struct mm_struct *mm, unsigned long start,
+		unsigned long nr_pages, struct page **pages,
+		struct vm_area_struct **vmas, int *locked,
+		unsigned int foll_flags)
+{
+	struct vm_area_struct *vma;
+	unsigned long vm_flags;
+	int i;
+
+	/* calculate required read or write permissions.
+	 * If FOLL_FORCE is set, we only require the "MAY" flags.
+	 */
+	vm_flags  = (foll_flags & FOLL_WRITE) ?
+			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
+	vm_flags &= (foll_flags & FOLL_FORCE) ?
+			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
+
+	for (i = 0; i < nr_pages; i++) {
+		vma = find_vma(mm, start);
+		if (!vma)
+			goto finish_or_fault;
+
+		/* protect what we can, including chardevs */
+		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
+		    !(vm_flags & vma->vm_flags))
+			goto finish_or_fault;
+
+		if (pages) {
+			pages[i] = virt_to_page(start);
+			if (pages[i])
+				get_page(pages[i]);
+		}
+		if (vmas)
+			vmas[i] = vma;
+		start = (start + PAGE_SIZE) & PAGE_MASK;
+	}
+
+	return i;
+
+finish_or_fault:
+	return i ? : -EFAULT;
+}
+#endif /* !CONFIG_MMU */
+
 #if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
 static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
 {
@@ -1416,7 +1530,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
 {
 	return nr_pages;
 }
-#endif
+#endif /* CONFIG_CMA */
 
 /*
  * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
@@ -1502,152 +1616,85 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 }
 EXPORT_SYMBOL(get_user_pages);
 
-/**
- * populate_vma_page_range() -  populate a range of pages in the vma.
- * @vma:   target vma
- * @start: start address
- * @end:   end address
- * @nonblocking:
- *
- * This takes care of mlocking the pages too if VM_LOCKED is set.
+/*
+ * We can leverage the VM_FAULT_RETRY functionality in the page fault
+ * paths better by using either get_user_pages_locked() or
+ * get_user_pages_unlocked().
  *
- * return 0 on success, negative error code on error.
+ * get_user_pages_locked() is suitable to replace the form:
  *
- * vma->vm_mm->mmap_sem must be held.
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
  *
- * If @nonblocking is NULL, it may be held for read or write and will
- * be unperturbed.
+ *  to:
  *
- * If @nonblocking is non-NULL, it must held for read only and may be
- * released.  If it's released, *@nonblocking will be set to 0.
+ *      int locked = 1;
+ *      down_read(&mm->mmap_sem);
+ *      do_something()
+ *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
+ *      if (locked)
+ *          up_read(&mm->mmap_sem);
  */
-long populate_vma_page_range(struct vm_area_struct *vma,
-		unsigned long start, unsigned long end, int *nonblocking)
+long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
+			   unsigned int gup_flags, struct page **pages,
+			   int *locked)
 {
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long nr_pages = (end - start) / PAGE_SIZE;
-	int gup_flags;
-
-	VM_BUG_ON(start & ~PAGE_MASK);
-	VM_BUG_ON(end   & ~PAGE_MASK);
-	VM_BUG_ON_VMA(start < vma->vm_start, vma);
-	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
-
-	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
-	if (vma->vm_flags & VM_LOCKONFAULT)
-		gup_flags &= ~FOLL_POPULATE;
-	/*
-	 * We want to touch writable mappings with a write fault in order
-	 * to break COW, except for shared mappings because these don't COW
-	 * and we would not want to dirty them for nothing.
-	 */
-	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
-		gup_flags |= FOLL_WRITE;
-
 	/*
-	 * We want mlock to succeed for regions that have any permissions
-	 * other than PROT_NONE.
+	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
+	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
+	 * vmas.  As there are no users of this flag in this call we simply
+	 * disallow this option for now.
 	 */
-	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
-		gup_flags |= FOLL_FORCE;
+	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+		return -EINVAL;
 
-	/*
-	 * We made sure addr is within a VMA, so the following will
-	 * not result in a stack expansion that recurses back here.
-	 */
-	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
-				NULL, NULL, nonblocking);
+	return __get_user_pages_locked(current, current->mm, start, nr_pages,
+				       pages, NULL, locked,
+				       gup_flags | FOLL_TOUCH);
 }
+EXPORT_SYMBOL(get_user_pages_locked);
 
 /*
- * __mm_populate - populate and/or mlock pages within a range of address space.
+ * get_user_pages_unlocked() is suitable to replace the form:
  *
- * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
- * flags. VMAs must be already marked with the desired vm_flags, and
- * mmap_sem must not be held.
+ *      down_read(&mm->mmap_sem);
+ *      get_user_pages(tsk, mm, ..., pages, NULL);
+ *      up_read(&mm->mmap_sem);
+ *
+ *  with:
+ *
+ *      get_user_pages_unlocked(tsk, mm, ..., pages);
+ *
+ * It is functionally equivalent to get_user_pages_fast so
+ * get_user_pages_fast should be used instead if specific gup_flags
+ * (e.g. FOLL_FORCE) are not required.
  */
-int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
+long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
+			     struct page **pages, unsigned int gup_flags)
 {
 	struct mm_struct *mm = current->mm;
-	unsigned long end, nstart, nend;
-	struct vm_area_struct *vma = NULL;
-	int locked = 0;
-	long ret = 0;
+	int locked = 1;
+	long ret;
 
-	end = start + len;
+	/*
+	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
+	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
+	 * vmas.  As there are no users of this flag in this call we simply
+	 * disallow this option for now.
+	 */
+	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+		return -EINVAL;
 
-	for (nstart = start; nstart < end; nstart = nend) {
-		/*
-		 * We want to fault in pages for [nstart; end) address range.
-		 * Find first corresponding VMA.
-		 */
-		if (!locked) {
-			locked = 1;
-			down_read(&mm->mmap_sem);
-			vma = find_vma(mm, nstart);
-		} else if (nstart >= vma->vm_end)
-			vma = vma->vm_next;
-		if (!vma || vma->vm_start >= end)
-			break;
-		/*
-		 * Set [nstart; nend) to intersection of desired address
-		 * range with the first VMA. Also, skip undesirable VMA types.
-		 */
-		nend = min(end, vma->vm_end);
-		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
-			continue;
-		if (nstart < vma->vm_start)
-			nstart = vma->vm_start;
-		/*
-		 * Now fault in a range of pages. populate_vma_page_range()
-		 * double checks the vma flags, so that it won't mlock pages
-		 * if the vma was already munlocked.
-		 */
-		ret = populate_vma_page_range(vma, nstart, nend, &locked);
-		if (ret < 0) {
-			if (ignore_errors) {
-				ret = 0;
-				continue;	/* continue at next VMA */
-			}
-			break;
-		}
-		nend = nstart + ret * PAGE_SIZE;
-		ret = 0;
-	}
+	down_read(&mm->mmap_sem);
+	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
+				      &locked, gup_flags | FOLL_TOUCH);
 	if (locked)
 		up_read(&mm->mmap_sem);
-	return ret;	/* 0 or negative error code */
-}
-
-/**
- * get_dump_page() - pin user page in memory while writing it to core dump
- * @addr: user address
- *
- * Returns struct page pointer of user page pinned for dump,
- * to be freed afterwards by put_page().
- *
- * Returns NULL on any kind of failure - a hole must then be inserted into
- * the corefile, to preserve alignment with its headers; and also returns
- * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
- * allowing a hole to be left in the corefile to save diskspace.
- *
- * Called without mmap_sem, but after all other threads have been killed.
- */
-#ifdef CONFIG_ELF_CORE
-struct page *get_dump_page(unsigned long addr)
-{
-	struct vm_area_struct *vma;
-	struct page *page;
-
-	if (__get_user_pages(current, current->mm, addr, 1,
-			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
-			     NULL) < 1)
-		return NULL;
-	flush_cache_page(vma, addr, page_to_pfn(page));
-	return page;
+	return ret;
 }
-#endif /* CONFIG_ELF_CORE */
+EXPORT_SYMBOL(get_user_pages_unlocked);
 
 /*
  * Fast GUP
@@ -1682,7 +1729,7 @@ struct page *get_dump_page(unsigned long addr)
  *
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
-#ifdef CONFIG_HAVE_FAST_GUP
+#if defined(CONFIG_MMU) && defined(CONFIG_HAVE_FAST_GUP)
 #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
 /*
  * WARNING: only to be used in the get_user_pages_fast() implementation.
@@ -2159,6 +2206,12 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
 			return;
 	} while (pgdp++, addr = next, addr != end);
 }
+#else
+static inline void gup_pgd_range(unsigned long addr, unsigned long end,
+		unsigned int flags, struct page **pages, int *nr)
+{
+}
+#endif /* CONFIG_HAVE_FAST_GUP */
 
 #ifndef gup_fast_permitted
 /*
@@ -2167,7 +2220,7 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
  */
 static bool gup_fast_permitted(unsigned long start, unsigned long end)
 {
-	return true;
+	return IS_ENABLED(CONFIG_HAVE_FAST_GUP) ? true : false;
 }
 #endif
 
@@ -2176,6 +2229,9 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
  * the regular GUP.
  * Note a difference with get_user_pages_fast: this always returns the
  * number of pages pinned, 0 if no pages were pinned.
+ *
+ * If the architecture does not support this function, simply return with no
+ * pages pinned.
  */
 int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			  struct page **pages)
@@ -2213,6 +2269,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 
 	return nr;
 }
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);
 
 static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
 				   unsigned int gup_flags, struct page **pages)
@@ -2295,5 +2352,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 
 	return ret;
 }
-
-#endif /* CONFIG_HAVE_GENERIC_GUP */
+EXPORT_SYMBOL_GPL(get_user_pages_fast);
diff --git a/mm/nommu.c b/mm/nommu.c
index d8c02fbe03b5..07165ad2e548 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -111,94 +111,6 @@ unsigned int kobjsize(const void *objp)
 	return PAGE_SIZE << compound_order(page);
 }
 
-static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-		      unsigned long start, unsigned long nr_pages,
-		      unsigned int foll_flags, struct page **pages,
-		      struct vm_area_struct **vmas, int *nonblocking)
-{
-	struct vm_area_struct *vma;
-	unsigned long vm_flags;
-	int i;
-
-	/* calculate required read or write permissions.
-	 * If FOLL_FORCE is set, we only require the "MAY" flags.
-	 */
-	vm_flags  = (foll_flags & FOLL_WRITE) ?
-			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
-	vm_flags &= (foll_flags & FOLL_FORCE) ?
-			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
-
-	for (i = 0; i < nr_pages; i++) {
-		vma = find_vma(mm, start);
-		if (!vma)
-			goto finish_or_fault;
-
-		/* protect what we can, including chardevs */
-		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
-		    !(vm_flags & vma->vm_flags))
-			goto finish_or_fault;
-
-		if (pages) {
-			pages[i] = virt_to_page(start);
-			if (pages[i])
-				get_page(pages[i]);
-		}
-		if (vmas)
-			vmas[i] = vma;
-		start = (start + PAGE_SIZE) & PAGE_MASK;
-	}
-
-	return i;
-
-finish_or_fault:
-	return i ? : -EFAULT;
-}
-
-/*
- * get a list of pages in an address range belonging to the specified process
- * and indicate the VMA that covers each page
- * - this is potentially dodgy as we may end incrementing the page count of a
- *   slab page or a secondary page from a compound page
- * - don't permit access to VMAs that don't support it, such as I/O mappings
- */
-long get_user_pages(unsigned long start, unsigned long nr_pages,
-		    unsigned int gup_flags, struct page **pages,
-		    struct vm_area_struct **vmas)
-{
-	return __get_user_pages(current, current->mm, start, nr_pages,
-				gup_flags, pages, vmas, NULL);
-}
-EXPORT_SYMBOL(get_user_pages);
-
-long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			    unsigned int gup_flags, struct page **pages,
-			    int *locked)
-{
-	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
-}
-EXPORT_SYMBOL(get_user_pages_locked);
-
-static long __get_user_pages_unlocked(struct task_struct *tsk,
-			struct mm_struct *mm, unsigned long start,
-			unsigned long nr_pages, struct page **pages,
-			unsigned int gup_flags)
-{
-	long ret;
-	down_read(&mm->mmap_sem);
-	ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
-				NULL, NULL);
-	up_read(&mm->mmap_sem);
-	return ret;
-}
-
-long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     struct page **pages, unsigned int gup_flags)
-{
-	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 pages, gup_flags);
-}
-EXPORT_SYMBOL(get_user_pages_unlocked);
-
 /**
  * follow_pfn - look up PFN at a user virtual address
  * @vma: memory mapping
diff --git a/mm/util.c b/mm/util.c
index 91682a2090ee..d58f5b0eb669 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -300,53 +300,6 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 }
 #endif
 
-/*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- * If the architecture does not support this function, simply return with no
- * pages pinned.
- */
-int __weak __get_user_pages_fast(unsigned long start,
-				 int nr_pages, int write, struct page **pages)
-{
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__get_user_pages_fast);
-
-/**
- * get_user_pages_fast() - pin user pages in memory
- * @start:	starting user address
- * @nr_pages:	number of pages from start to pin
- * @gup_flags:	flags modifying pin behaviour
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_pages long.
- *
- * get_user_pages_fast provides equivalent functionality to get_user_pages,
- * operating on current and current->mm, with force=0 and vma=NULL. However
- * unlike get_user_pages, it must be called without mmap_sem held.
- *
- * get_user_pages_fast may take mmap_sem and page table locks, so no
- * assumptions can be made about lack of locking. get_user_pages_fast is to be
- * implemented in a way that is advantageous (vs get_user_pages()) when the
- * user memory area is already faulted in and present in ptes. However if the
- * pages have to be faulted in, it may turn out to be slightly slower so
- * callers need to carefully consider what to use. On many architectures,
- * get_user_pages_fast simply falls back to get_user_pages.
- *
- * Return: number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- */
-int __weak get_user_pages_fast(unsigned long start,
-				int nr_pages, unsigned int gup_flags,
-				struct page **pages)
-{
-	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
-}
-EXPORT_SYMBOL_GPL(get_user_pages_fast);
-
 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,
 	unsigned long flag, unsigned long pgoff)
-- 
2.20.1

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[John Hubbard]

On 6/1/19 12:49 AM, Christoph Hellwig wrote:
> Always build mm/gup.c, and move the nommu versions and replace the
> separate stubs for various functions by the default ones, with the _fast
> version always falling back to the slow path because gup_fast_permitted
> always returns false now if HAVE_FAST_GUP is not set, and we use the
> nommu version of __get_user_pages while keeping all the wrappers common.
> 
> This also ensures the new put_user_pages* helpers are available for
> nommu, as those are currently missing, which would create a problem as
> soon as we actually grew users for it.
> 

Hi Christoph,

Thanks for fixing up the nommu case. And the patchset overall is a huge
relief to see, because I'd filed those arches under the "despair" category
for the gup conversions. :)

I started reviewing this one patch, and it's kind of messy figuring out 
if the code motion preserves everything because of
all the consolidation from other places, plus having to move things in
and out of the ifdef blocks.  So I figured I'd check and see if this is
going to make it past RFC status soon, and if it's going before or after
Ira's recent RFC ("RDMA/FS DAX truncate proposal").


thanks,
-- 
John Hubbard
NVIDIA

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  mm/Kconfig  |   1 +
>  mm/Makefile |   4 +-
>  mm/gup.c    | 476 +++++++++++++++++++++++++++++-----------------------
>  mm/nommu.c  |  88 ----------
>  mm/util.c   |  47 ------
>  5 files changed, 269 insertions(+), 347 deletions(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 98dffb0f2447..5c41409557da 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -133,6 +133,7 @@ config HAVE_MEMBLOCK_PHYS_MAP
>  	bool
>  
>  config HAVE_FAST_GUP
> +	depends on MMU
>  	bool
>  
>  config ARCH_KEEP_MEMBLOCK
> diff --git a/mm/Makefile b/mm/Makefile
> index ac5e5ba78874..dc0746ca1109 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -22,7 +22,7 @@ KCOV_INSTRUMENT_mmzone.o := n
>  KCOV_INSTRUMENT_vmstat.o := n
>  
>  mmu-y			:= nommu.o
> -mmu-$(CONFIG_MMU)	:= gup.o highmem.o memory.o mincore.o \
> +mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
>  			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
>  			   msync.o page_vma_mapped.o pagewalk.o \
>  			   pgtable-generic.o rmap.o vmalloc.o
> @@ -39,7 +39,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
>  			   mm_init.o mmu_context.o percpu.o slab_common.o \
>  			   compaction.o vmacache.o \
>  			   interval_tree.o list_lru.o workingset.o \
> -			   debug.o $(mmu-y)
> +			   debug.o gup.o $(mmu-y)
>  
>  # Give 'page_alloc' its own module-parameter namespace
>  page-alloc-y := page_alloc.o
> diff --git a/mm/gup.c b/mm/gup.c
> index a24f52292c7f..c8da7764de9c 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -134,6 +134,7 @@ void put_user_pages(struct page **pages, unsigned long npages)
>  }
>  EXPORT_SYMBOL(put_user_pages);
>  
> +#ifdef CONFIG_MMU
>  static struct page *no_page_table(struct vm_area_struct *vma,
>  		unsigned int flags)
>  {
> @@ -1099,86 +1100,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
>  	return pages_done;
>  }
>  
> -/*
> - * We can leverage the VM_FAULT_RETRY functionality in the page fault
> - * paths better by using either get_user_pages_locked() or
> - * get_user_pages_unlocked().
> - *
> - * get_user_pages_locked() is suitable to replace the form:
> - *
> - *      down_read(&mm->mmap_sem);
> - *      do_something()
> - *      get_user_pages(tsk, mm, ..., pages, NULL);
> - *      up_read(&mm->mmap_sem);
> - *
> - *  to:
> - *
> - *      int locked = 1;
> - *      down_read(&mm->mmap_sem);
> - *      do_something()
> - *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
> - *      if (locked)
> - *          up_read(&mm->mmap_sem);
> - */
> -long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> -			   unsigned int gup_flags, struct page **pages,
> -			   int *locked)
> -{
> -	/*
> -	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> -	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> -	 * vmas.  As there are no users of this flag in this call we simply
> -	 * disallow this option for now.
> -	 */
> -	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> -		return -EINVAL;
> -
> -	return __get_user_pages_locked(current, current->mm, start, nr_pages,
> -				       pages, NULL, locked,
> -				       gup_flags | FOLL_TOUCH);
> -}
> -EXPORT_SYMBOL(get_user_pages_locked);
> -
> -/*
> - * get_user_pages_unlocked() is suitable to replace the form:
> - *
> - *      down_read(&mm->mmap_sem);
> - *      get_user_pages(tsk, mm, ..., pages, NULL);
> - *      up_read(&mm->mmap_sem);
> - *
> - *  with:
> - *
> - *      get_user_pages_unlocked(tsk, mm, ..., pages);
> - *
> - * It is functionally equivalent to get_user_pages_fast so
> - * get_user_pages_fast should be used instead if specific gup_flags
> - * (e.g. FOLL_FORCE) are not required.
> - */
> -long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> -			     struct page **pages, unsigned int gup_flags)
> -{
> -	struct mm_struct *mm = current->mm;
> -	int locked = 1;
> -	long ret;
> -
> -	/*
> -	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> -	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> -	 * vmas.  As there are no users of this flag in this call we simply
> -	 * disallow this option for now.
> -	 */
> -	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> -		return -EINVAL;
> -
> -	down_read(&mm->mmap_sem);
> -	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
> -				      &locked, gup_flags | FOLL_TOUCH);
> -	if (locked)
> -		up_read(&mm->mmap_sem);
> -	return ret;
> -}
> -EXPORT_SYMBOL(get_user_pages_unlocked);
> -
>  /*
>   * get_user_pages_remote() - pin user pages in memory
>   * @tsk:	the task_struct to use for page fault accounting, or
> @@ -1255,6 +1176,199 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
>  }
>  EXPORT_SYMBOL(get_user_pages_remote);
>  
> +/**
> + * populate_vma_page_range() -  populate a range of pages in the vma.
> + * @vma:   target vma
> + * @start: start address
> + * @end:   end address
> + * @nonblocking:
> + *
> + * This takes care of mlocking the pages too if VM_LOCKED is set.
> + *
> + * return 0 on success, negative error code on error.
> + *
> + * vma->vm_mm->mmap_sem must be held.
> + *
> + * If @nonblocking is NULL, it may be held for read or write and will
> + * be unperturbed.
> + *
> + * If @nonblocking is non-NULL, it must held for read only and may be
> + * released.  If it's released, *@nonblocking will be set to 0.
> + */
> +long populate_vma_page_range(struct vm_area_struct *vma,
> +		unsigned long start, unsigned long end, int *nonblocking)
> +{
> +	struct mm_struct *mm = vma->vm_mm;
> +	unsigned long nr_pages = (end - start) / PAGE_SIZE;
> +	int gup_flags;
> +
> +	VM_BUG_ON(start & ~PAGE_MASK);
> +	VM_BUG_ON(end   & ~PAGE_MASK);
> +	VM_BUG_ON_VMA(start < vma->vm_start, vma);
> +	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
> +	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> +
> +	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
> +	if (vma->vm_flags & VM_LOCKONFAULT)
> +		gup_flags &= ~FOLL_POPULATE;
> +	/*
> +	 * We want to touch writable mappings with a write fault in order
> +	 * to break COW, except for shared mappings because these don't COW
> +	 * and we would not want to dirty them for nothing.
> +	 */
> +	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) = VM_WRITE)
> +		gup_flags |= FOLL_WRITE;
> +
> +	/*
> +	 * We want mlock to succeed for regions that have any permissions
> +	 * other than PROT_NONE.
> +	 */
> +	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
> +		gup_flags |= FOLL_FORCE;
> +
> +	/*
> +	 * We made sure addr is within a VMA, so the following will
> +	 * not result in a stack expansion that recurses back here.
> +	 */
> +	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
> +				NULL, NULL, nonblocking);
> +}
> +
> +/*
> + * __mm_populate - populate and/or mlock pages within a range of address space.
> + *
> + * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
> + * flags. VMAs must be already marked with the desired vm_flags, and
> + * mmap_sem must not be held.
> + */
> +int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> +{
> +	struct mm_struct *mm = current->mm;
> +	unsigned long end, nstart, nend;
> +	struct vm_area_struct *vma = NULL;
> +	int locked = 0;
> +	long ret = 0;
> +
> +	end = start + len;
> +
> +	for (nstart = start; nstart < end; nstart = nend) {
> +		/*
> +		 * We want to fault in pages for [nstart; end) address range.
> +		 * Find first corresponding VMA.
> +		 */
> +		if (!locked) {
> +			locked = 1;
> +			down_read(&mm->mmap_sem);
> +			vma = find_vma(mm, nstart);
> +		} else if (nstart >= vma->vm_end)
> +			vma = vma->vm_next;
> +		if (!vma || vma->vm_start >= end)
> +			break;
> +		/*
> +		 * Set [nstart; nend) to intersection of desired address
> +		 * range with the first VMA. Also, skip undesirable VMA types.
> +		 */
> +		nend = min(end, vma->vm_end);
> +		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
> +			continue;
> +		if (nstart < vma->vm_start)
> +			nstart = vma->vm_start;
> +		/*
> +		 * Now fault in a range of pages. populate_vma_page_range()
> +		 * double checks the vma flags, so that it won't mlock pages
> +		 * if the vma was already munlocked.
> +		 */
> +		ret = populate_vma_page_range(vma, nstart, nend, &locked);
> +		if (ret < 0) {
> +			if (ignore_errors) {
> +				ret = 0;
> +				continue;	/* continue at next VMA */
> +			}
> +			break;
> +		}
> +		nend = nstart + ret * PAGE_SIZE;
> +		ret = 0;
> +	}
> +	if (locked)
> +		up_read(&mm->mmap_sem);
> +	return ret;	/* 0 or negative error code */
> +}
> +
> +/**
> + * get_dump_page() - pin user page in memory while writing it to core dump
> + * @addr: user address
> + *
> + * Returns struct page pointer of user page pinned for dump,
> + * to be freed afterwards by put_page().
> + *
> + * Returns NULL on any kind of failure - a hole must then be inserted into
> + * the corefile, to preserve alignment with its headers; and also returns
> + * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
> + * allowing a hole to be left in the corefile to save diskspace.
> + *
> + * Called without mmap_sem, but after all other threads have been killed.
> + */
> +#ifdef CONFIG_ELF_CORE
> +struct page *get_dump_page(unsigned long addr)
> +{
> +	struct vm_area_struct *vma;
> +	struct page *page;
> +
> +	if (__get_user_pages(current, current->mm, addr, 1,
> +			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
> +			     NULL) < 1)
> +		return NULL;
> +	flush_cache_page(vma, addr, page_to_pfn(page));
> +	return page;
> +}
> +#endif /* CONFIG_ELF_CORE */
> +
> +#else /* CONFIG_MMU */
> +static long __get_user_pages_locked(struct task_struct *tsk,
> +		struct mm_struct *mm, unsigned long start,
> +		unsigned long nr_pages, struct page **pages,
> +		struct vm_area_struct **vmas, int *locked,
> +		unsigned int foll_flags)
> +{
> +	struct vm_area_struct *vma;
> +	unsigned long vm_flags;
> +	int i;
> +
> +	/* calculate required read or write permissions.
> +	 * If FOLL_FORCE is set, we only require the "MAY" flags.
> +	 */
> +	vm_flags  = (foll_flags & FOLL_WRITE) ?
> +			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
> +	vm_flags &= (foll_flags & FOLL_FORCE) ?
> +			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
> +
> +	for (i = 0; i < nr_pages; i++) {
> +		vma = find_vma(mm, start);
> +		if (!vma)
> +			goto finish_or_fault;
> +
> +		/* protect what we can, including chardevs */
> +		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
> +		    !(vm_flags & vma->vm_flags))
> +			goto finish_or_fault;
> +
> +		if (pages) {
> +			pages[i] = virt_to_page(start);
> +			if (pages[i])
> +				get_page(pages[i]);
> +		}
> +		if (vmas)
> +			vmas[i] = vma;
> +		start = (start + PAGE_SIZE) & PAGE_MASK;
> +	}
> +
> +	return i;
> +
> +finish_or_fault:
> +	return i ? : -EFAULT;
> +}
> +#endif /* !CONFIG_MMU */
> +
>  #if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
>  static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
>  {
> @@ -1416,7 +1530,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
>  {
>  	return nr_pages;
>  }
> -#endif
> +#endif /* CONFIG_CMA */
>  
>  /*
>   * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
> @@ -1502,152 +1616,85 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
>  }
>  EXPORT_SYMBOL(get_user_pages);
>  
> -/**
> - * populate_vma_page_range() -  populate a range of pages in the vma.
> - * @vma:   target vma
> - * @start: start address
> - * @end:   end address
> - * @nonblocking:
> - *
> - * This takes care of mlocking the pages too if VM_LOCKED is set.
> +/*
> + * We can leverage the VM_FAULT_RETRY functionality in the page fault
> + * paths better by using either get_user_pages_locked() or
> + * get_user_pages_unlocked().
>   *
> - * return 0 on success, negative error code on error.
> + * get_user_pages_locked() is suitable to replace the form:
>   *
> - * vma->vm_mm->mmap_sem must be held.
> + *      down_read(&mm->mmap_sem);
> + *      do_something()
> + *      get_user_pages(tsk, mm, ..., pages, NULL);
> + *      up_read(&mm->mmap_sem);
>   *
> - * If @nonblocking is NULL, it may be held for read or write and will
> - * be unperturbed.
> + *  to:
>   *
> - * If @nonblocking is non-NULL, it must held for read only and may be
> - * released.  If it's released, *@nonblocking will be set to 0.
> + *      int locked = 1;
> + *      down_read(&mm->mmap_sem);
> + *      do_something()
> + *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
> + *      if (locked)
> + *          up_read(&mm->mmap_sem);
>   */
> -long populate_vma_page_range(struct vm_area_struct *vma,
> -		unsigned long start, unsigned long end, int *nonblocking)
> +long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> +			   unsigned int gup_flags, struct page **pages,
> +			   int *locked)
>  {
> -	struct mm_struct *mm = vma->vm_mm;
> -	unsigned long nr_pages = (end - start) / PAGE_SIZE;
> -	int gup_flags;
> -
> -	VM_BUG_ON(start & ~PAGE_MASK);
> -	VM_BUG_ON(end   & ~PAGE_MASK);
> -	VM_BUG_ON_VMA(start < vma->vm_start, vma);
> -	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
> -	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> -
> -	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
> -	if (vma->vm_flags & VM_LOCKONFAULT)
> -		gup_flags &= ~FOLL_POPULATE;
> -	/*
> -	 * We want to touch writable mappings with a write fault in order
> -	 * to break COW, except for shared mappings because these don't COW
> -	 * and we would not want to dirty them for nothing.
> -	 */
> -	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) = VM_WRITE)
> -		gup_flags |= FOLL_WRITE;
> -
>  	/*
> -	 * We want mlock to succeed for regions that have any permissions
> -	 * other than PROT_NONE.
> +	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> +	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> +	 * vmas.  As there are no users of this flag in this call we simply
> +	 * disallow this option for now.
>  	 */
> -	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
> -		gup_flags |= FOLL_FORCE;
> +	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> +		return -EINVAL;
>  
> -	/*
> -	 * We made sure addr is within a VMA, so the following will
> -	 * not result in a stack expansion that recurses back here.
> -	 */
> -	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
> -				NULL, NULL, nonblocking);
> +	return __get_user_pages_locked(current, current->mm, start, nr_pages,
> +				       pages, NULL, locked,
> +				       gup_flags | FOLL_TOUCH);
>  }
> +EXPORT_SYMBOL(get_user_pages_locked);
>  
>  /*
> - * __mm_populate - populate and/or mlock pages within a range of address space.
> + * get_user_pages_unlocked() is suitable to replace the form:
>   *
> - * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
> - * flags. VMAs must be already marked with the desired vm_flags, and
> - * mmap_sem must not be held.
> + *      down_read(&mm->mmap_sem);
> + *      get_user_pages(tsk, mm, ..., pages, NULL);
> + *      up_read(&mm->mmap_sem);
> + *
> + *  with:
> + *
> + *      get_user_pages_unlocked(tsk, mm, ..., pages);
> + *
> + * It is functionally equivalent to get_user_pages_fast so
> + * get_user_pages_fast should be used instead if specific gup_flags
> + * (e.g. FOLL_FORCE) are not required.
>   */
> -int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> +long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> +			     struct page **pages, unsigned int gup_flags)
>  {
>  	struct mm_struct *mm = current->mm;
> -	unsigned long end, nstart, nend;
> -	struct vm_area_struct *vma = NULL;
> -	int locked = 0;
> -	long ret = 0;
> +	int locked = 1;
> +	long ret;
>  
> -	end = start + len;
> +	/*
> +	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> +	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> +	 * vmas.  As there are no users of this flag in this call we simply
> +	 * disallow this option for now.
> +	 */
> +	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> +		return -EINVAL;
>  
> -	for (nstart = start; nstart < end; nstart = nend) {
> -		/*
> -		 * We want to fault in pages for [nstart; end) address range.
> -		 * Find first corresponding VMA.
> -		 */
> -		if (!locked) {
> -			locked = 1;
> -			down_read(&mm->mmap_sem);
> -			vma = find_vma(mm, nstart);
> -		} else if (nstart >= vma->vm_end)
> -			vma = vma->vm_next;
> -		if (!vma || vma->vm_start >= end)
> -			break;
> -		/*
> -		 * Set [nstart; nend) to intersection of desired address
> -		 * range with the first VMA. Also, skip undesirable VMA types.
> -		 */
> -		nend = min(end, vma->vm_end);
> -		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
> -			continue;
> -		if (nstart < vma->vm_start)
> -			nstart = vma->vm_start;
> -		/*
> -		 * Now fault in a range of pages. populate_vma_page_range()
> -		 * double checks the vma flags, so that it won't mlock pages
> -		 * if the vma was already munlocked.
> -		 */
> -		ret = populate_vma_page_range(vma, nstart, nend, &locked);
> -		if (ret < 0) {
> -			if (ignore_errors) {
> -				ret = 0;
> -				continue;	/* continue at next VMA */
> -			}
> -			break;
> -		}
> -		nend = nstart + ret * PAGE_SIZE;
> -		ret = 0;
> -	}
> +	down_read(&mm->mmap_sem);
> +	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
> +				      &locked, gup_flags | FOLL_TOUCH);
>  	if (locked)
>  		up_read(&mm->mmap_sem);
> -	return ret;	/* 0 or negative error code */
> -}
> -
> -/**
> - * get_dump_page() - pin user page in memory while writing it to core dump
> - * @addr: user address
> - *
> - * Returns struct page pointer of user page pinned for dump,
> - * to be freed afterwards by put_page().
> - *
> - * Returns NULL on any kind of failure - a hole must then be inserted into
> - * the corefile, to preserve alignment with its headers; and also returns
> - * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
> - * allowing a hole to be left in the corefile to save diskspace.
> - *
> - * Called without mmap_sem, but after all other threads have been killed.
> - */
> -#ifdef CONFIG_ELF_CORE
> -struct page *get_dump_page(unsigned long addr)
> -{
> -	struct vm_area_struct *vma;
> -	struct page *page;
> -
> -	if (__get_user_pages(current, current->mm, addr, 1,
> -			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
> -			     NULL) < 1)
> -		return NULL;
> -	flush_cache_page(vma, addr, page_to_pfn(page));
> -	return page;
> +	return ret;
>  }
> -#endif /* CONFIG_ELF_CORE */
> +EXPORT_SYMBOL(get_user_pages_unlocked);
>  
>  /*
>   * Fast GUP
> @@ -1682,7 +1729,7 @@ struct page *get_dump_page(unsigned long addr)
>   *
>   * This code is based heavily on the PowerPC implementation by Nick Piggin.
>   */
> -#ifdef CONFIG_HAVE_FAST_GUP
> +#if defined(CONFIG_MMU) && defined(CONFIG_HAVE_FAST_GUP)
>  #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
>  /*
>   * WARNING: only to be used in the get_user_pages_fast() implementation.
> @@ -2159,6 +2206,12 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>  			return;
>  	} while (pgdp++, addr = next, addr != end);
>  }
> +#else
> +static inline void gup_pgd_range(unsigned long addr, unsigned long end,
> +		unsigned int flags, struct page **pages, int *nr)
> +{
> +}
> +#endif /* CONFIG_HAVE_FAST_GUP */
>  
>  #ifndef gup_fast_permitted
>  /*
> @@ -2167,7 +2220,7 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>   */
>  static bool gup_fast_permitted(unsigned long start, unsigned long end)
>  {
> -	return true;
> +	return IS_ENABLED(CONFIG_HAVE_FAST_GUP) ? true : false;
>  }
>  #endif
>  
> @@ -2176,6 +2229,9 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
>   * the regular GUP.
>   * Note a difference with get_user_pages_fast: this always returns the
>   * number of pages pinned, 0 if no pages were pinned.
> + *
> + * If the architecture does not support this function, simply return with no
> + * pages pinned.
>   */
>  int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  			  struct page **pages)
> @@ -2213,6 +2269,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  
>  	return nr;
>  }
> +EXPORT_SYMBOL_GPL(__get_user_pages_fast);
>  
>  static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
>  				   unsigned int gup_flags, struct page **pages)
> @@ -2295,5 +2352,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
>  
>  	return ret;
>  }
> -
> -#endif /* CONFIG_HAVE_GENERIC_GUP */
> +EXPORT_SYMBOL_GPL(get_user_pages_fast);
> diff --git a/mm/nommu.c b/mm/nommu.c
> index d8c02fbe03b5..07165ad2e548 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -111,94 +111,6 @@ unsigned int kobjsize(const void *objp)
>  	return PAGE_SIZE << compound_order(page);
>  }
>  
> -static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> -		      unsigned long start, unsigned long nr_pages,
> -		      unsigned int foll_flags, struct page **pages,
> -		      struct vm_area_struct **vmas, int *nonblocking)
> -{
> -	struct vm_area_struct *vma;
> -	unsigned long vm_flags;
> -	int i;
> -
> -	/* calculate required read or write permissions.
> -	 * If FOLL_FORCE is set, we only require the "MAY" flags.
> -	 */
> -	vm_flags  = (foll_flags & FOLL_WRITE) ?
> -			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
> -	vm_flags &= (foll_flags & FOLL_FORCE) ?
> -			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
> -
> -	for (i = 0; i < nr_pages; i++) {
> -		vma = find_vma(mm, start);
> -		if (!vma)
> -			goto finish_or_fault;
> -
> -		/* protect what we can, including chardevs */
> -		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
> -		    !(vm_flags & vma->vm_flags))
> -			goto finish_or_fault;
> -
> -		if (pages) {
> -			pages[i] = virt_to_page(start);
> -			if (pages[i])
> -				get_page(pages[i]);
> -		}
> -		if (vmas)
> -			vmas[i] = vma;
> -		start = (start + PAGE_SIZE) & PAGE_MASK;
> -	}
> -
> -	return i;
> -
> -finish_or_fault:
> -	return i ? : -EFAULT;
> -}
> -
> -/*
> - * get a list of pages in an address range belonging to the specified process
> - * and indicate the VMA that covers each page
> - * - this is potentially dodgy as we may end incrementing the page count of a
> - *   slab page or a secondary page from a compound page
> - * - don't permit access to VMAs that don't support it, such as I/O mappings
> - */
> -long get_user_pages(unsigned long start, unsigned long nr_pages,
> -		    unsigned int gup_flags, struct page **pages,
> -		    struct vm_area_struct **vmas)
> -{
> -	return __get_user_pages(current, current->mm, start, nr_pages,
> -				gup_flags, pages, vmas, NULL);
> -}
> -EXPORT_SYMBOL(get_user_pages);
> -
> -long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> -			    unsigned int gup_flags, struct page **pages,
> -			    int *locked)
> -{
> -	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
> -}
> -EXPORT_SYMBOL(get_user_pages_locked);
> -
> -static long __get_user_pages_unlocked(struct task_struct *tsk,
> -			struct mm_struct *mm, unsigned long start,
> -			unsigned long nr_pages, struct page **pages,
> -			unsigned int gup_flags)
> -{
> -	long ret;
> -	down_read(&mm->mmap_sem);
> -	ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
> -				NULL, NULL);
> -	up_read(&mm->mmap_sem);
> -	return ret;
> -}
> -
> -long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> -			     struct page **pages, unsigned int gup_flags)
> -{
> -	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
> -					 pages, gup_flags);
> -}
> -EXPORT_SYMBOL(get_user_pages_unlocked);
> -
>  /**
>   * follow_pfn - look up PFN at a user virtual address
>   * @vma: memory mapping
> diff --git a/mm/util.c b/mm/util.c
> index 91682a2090ee..d58f5b0eb669 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -300,53 +300,6 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>  }
>  #endif
>  
> -/*
> - * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
> - * back to the regular GUP.
> - * Note a difference with get_user_pages_fast: this always returns the
> - * number of pages pinned, 0 if no pages were pinned.
> - * If the architecture does not support this function, simply return with no
> - * pages pinned.
> - */
> -int __weak __get_user_pages_fast(unsigned long start,
> -				 int nr_pages, int write, struct page **pages)
> -{
> -	return 0;
> -}
> -EXPORT_SYMBOL_GPL(__get_user_pages_fast);
> -
> -/**
> - * get_user_pages_fast() - pin user pages in memory
> - * @start:	starting user address
> - * @nr_pages:	number of pages from start to pin
> - * @gup_flags:	flags modifying pin behaviour
> - * @pages:	array that receives pointers to the pages pinned.
> - *		Should be at least nr_pages long.
> - *
> - * get_user_pages_fast provides equivalent functionality to get_user_pages,
> - * operating on current and current->mm, with force=0 and vma=NULL. However
> - * unlike get_user_pages, it must be called without mmap_sem held.
> - *
> - * get_user_pages_fast may take mmap_sem and page table locks, so no
> - * assumptions can be made about lack of locking. get_user_pages_fast is to be
> - * implemented in a way that is advantageous (vs get_user_pages()) when the
> - * user memory area is already faulted in and present in ptes. However if the
> - * pages have to be faulted in, it may turn out to be slightly slower so
> - * callers need to carefully consider what to use. On many architectures,
> - * get_user_pages_fast simply falls back to get_user_pages.
> - *
> - * Return: number of pages pinned. This may be fewer than the number
> - * requested. If nr_pages is 0 or negative, returns 0. If no pages
> - * were pinned, returns -errno.
> - */
> -int __weak get_user_pages_fast(unsigned long start,
> -				int nr_pages, unsigned int gup_flags,
> -				struct page **pages)
> -{
> -	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
> -}
> -EXPORT_SYMBOL_GPL(get_user_pages_fast);
> -
>  unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
>  	unsigned long len, unsigned long prot,
>  	unsigned long flag, unsigned long pgoff)
> 

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[John Hubbard]

On 6/1/19 12:49 AM, Christoph Hellwig wrote:
> Always build mm/gup.c, and move the nommu versions and replace the
> separate stubs for various functions by the default ones, with the _fast
> version always falling back to the slow path because gup_fast_permitted
> always returns false now if HAVE_FAST_GUP is not set, and we use the
> nommu version of __get_user_pages while keeping all the wrappers common.
> 
> This also ensures the new put_user_pages* helpers are available for
> nommu, as those are currently missing, which would create a problem as
> soon as we actually grew users for it.
> 

Hi Christoph,

Thanks for fixing up the nommu case. And the patchset overall is a huge
relief to see, because I'd filed those arches under the "despair" category
for the gup conversions. :)

I started reviewing this one patch, and it's kind of messy figuring out 
if the code motion preserves everything because of
all the consolidation from other places, plus having to move things in
and out of the ifdef blocks.  So I figured I'd check and see if this is
going to make it past RFC status soon, and if it's going before or after
Ira's recent RFC ("RDMA/FS DAX truncate proposal").


thanks,
-- 
John Hubbard
NVIDIA

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  mm/Kconfig  |   1 +
>  mm/Makefile |   4 +-
>  mm/gup.c    | 476 +++++++++++++++++++++++++++++-----------------------
>  mm/nommu.c  |  88 ----------
>  mm/util.c   |  47 ------
>  5 files changed, 269 insertions(+), 347 deletions(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 98dffb0f2447..5c41409557da 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -133,6 +133,7 @@ config HAVE_MEMBLOCK_PHYS_MAP
>  	bool
>  
>  config HAVE_FAST_GUP
> +	depends on MMU
>  	bool
>  
>  config ARCH_KEEP_MEMBLOCK
> diff --git a/mm/Makefile b/mm/Makefile
> index ac5e5ba78874..dc0746ca1109 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -22,7 +22,7 @@ KCOV_INSTRUMENT_mmzone.o := n
>  KCOV_INSTRUMENT_vmstat.o := n
>  
>  mmu-y			:= nommu.o
> -mmu-$(CONFIG_MMU)	:= gup.o highmem.o memory.o mincore.o \
> +mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
>  			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
>  			   msync.o page_vma_mapped.o pagewalk.o \
>  			   pgtable-generic.o rmap.o vmalloc.o
> @@ -39,7 +39,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
>  			   mm_init.o mmu_context.o percpu.o slab_common.o \
>  			   compaction.o vmacache.o \
>  			   interval_tree.o list_lru.o workingset.o \
> -			   debug.o $(mmu-y)
> +			   debug.o gup.o $(mmu-y)
>  
>  # Give 'page_alloc' its own module-parameter namespace
>  page-alloc-y := page_alloc.o
> diff --git a/mm/gup.c b/mm/gup.c
> index a24f52292c7f..c8da7764de9c 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -134,6 +134,7 @@ void put_user_pages(struct page **pages, unsigned long npages)
>  }
>  EXPORT_SYMBOL(put_user_pages);
>  
> +#ifdef CONFIG_MMU
>  static struct page *no_page_table(struct vm_area_struct *vma,
>  		unsigned int flags)
>  {
> @@ -1099,86 +1100,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
>  	return pages_done;
>  }
>  
> -/*
> - * We can leverage the VM_FAULT_RETRY functionality in the page fault
> - * paths better by using either get_user_pages_locked() or
> - * get_user_pages_unlocked().
> - *
> - * get_user_pages_locked() is suitable to replace the form:
> - *
> - *      down_read(&mm->mmap_sem);
> - *      do_something()
> - *      get_user_pages(tsk, mm, ..., pages, NULL);
> - *      up_read(&mm->mmap_sem);
> - *
> - *  to:
> - *
> - *      int locked = 1;
> - *      down_read(&mm->mmap_sem);
> - *      do_something()
> - *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
> - *      if (locked)
> - *          up_read(&mm->mmap_sem);
> - */
> -long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> -			   unsigned int gup_flags, struct page **pages,
> -			   int *locked)
> -{
> -	/*
> -	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> -	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> -	 * vmas.  As there are no users of this flag in this call we simply
> -	 * disallow this option for now.
> -	 */
> -	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> -		return -EINVAL;
> -
> -	return __get_user_pages_locked(current, current->mm, start, nr_pages,
> -				       pages, NULL, locked,
> -				       gup_flags | FOLL_TOUCH);
> -}
> -EXPORT_SYMBOL(get_user_pages_locked);
> -
> -/*
> - * get_user_pages_unlocked() is suitable to replace the form:
> - *
> - *      down_read(&mm->mmap_sem);
> - *      get_user_pages(tsk, mm, ..., pages, NULL);
> - *      up_read(&mm->mmap_sem);
> - *
> - *  with:
> - *
> - *      get_user_pages_unlocked(tsk, mm, ..., pages);
> - *
> - * It is functionally equivalent to get_user_pages_fast so
> - * get_user_pages_fast should be used instead if specific gup_flags
> - * (e.g. FOLL_FORCE) are not required.
> - */
> -long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> -			     struct page **pages, unsigned int gup_flags)
> -{
> -	struct mm_struct *mm = current->mm;
> -	int locked = 1;
> -	long ret;
> -
> -	/*
> -	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> -	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> -	 * vmas.  As there are no users of this flag in this call we simply
> -	 * disallow this option for now.
> -	 */
> -	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> -		return -EINVAL;
> -
> -	down_read(&mm->mmap_sem);
> -	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
> -				      &locked, gup_flags | FOLL_TOUCH);
> -	if (locked)
> -		up_read(&mm->mmap_sem);
> -	return ret;
> -}
> -EXPORT_SYMBOL(get_user_pages_unlocked);
> -
>  /*
>   * get_user_pages_remote() - pin user pages in memory
>   * @tsk:	the task_struct to use for page fault accounting, or
> @@ -1255,6 +1176,199 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
>  }
>  EXPORT_SYMBOL(get_user_pages_remote);
>  
> +/**
> + * populate_vma_page_range() -  populate a range of pages in the vma.
> + * @vma:   target vma
> + * @start: start address
> + * @end:   end address
> + * @nonblocking:
> + *
> + * This takes care of mlocking the pages too if VM_LOCKED is set.
> + *
> + * return 0 on success, negative error code on error.
> + *
> + * vma->vm_mm->mmap_sem must be held.
> + *
> + * If @nonblocking is NULL, it may be held for read or write and will
> + * be unperturbed.
> + *
> + * If @nonblocking is non-NULL, it must held for read only and may be
> + * released.  If it's released, *@nonblocking will be set to 0.
> + */
> +long populate_vma_page_range(struct vm_area_struct *vma,
> +		unsigned long start, unsigned long end, int *nonblocking)
> +{
> +	struct mm_struct *mm = vma->vm_mm;
> +	unsigned long nr_pages = (end - start) / PAGE_SIZE;
> +	int gup_flags;
> +
> +	VM_BUG_ON(start & ~PAGE_MASK);
> +	VM_BUG_ON(end   & ~PAGE_MASK);
> +	VM_BUG_ON_VMA(start < vma->vm_start, vma);
> +	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
> +	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> +
> +	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
> +	if (vma->vm_flags & VM_LOCKONFAULT)
> +		gup_flags &= ~FOLL_POPULATE;
> +	/*
> +	 * We want to touch writable mappings with a write fault in order
> +	 * to break COW, except for shared mappings because these don't COW
> +	 * and we would not want to dirty them for nothing.
> +	 */
> +	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
> +		gup_flags |= FOLL_WRITE;
> +
> +	/*
> +	 * We want mlock to succeed for regions that have any permissions
> +	 * other than PROT_NONE.
> +	 */
> +	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
> +		gup_flags |= FOLL_FORCE;
> +
> +	/*
> +	 * We made sure addr is within a VMA, so the following will
> +	 * not result in a stack expansion that recurses back here.
> +	 */
> +	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
> +				NULL, NULL, nonblocking);
> +}
> +
> +/*
> + * __mm_populate - populate and/or mlock pages within a range of address space.
> + *
> + * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
> + * flags. VMAs must be already marked with the desired vm_flags, and
> + * mmap_sem must not be held.
> + */
> +int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> +{
> +	struct mm_struct *mm = current->mm;
> +	unsigned long end, nstart, nend;
> +	struct vm_area_struct *vma = NULL;
> +	int locked = 0;
> +	long ret = 0;
> +
> +	end = start + len;
> +
> +	for (nstart = start; nstart < end; nstart = nend) {
> +		/*
> +		 * We want to fault in pages for [nstart; end) address range.
> +		 * Find first corresponding VMA.
> +		 */
> +		if (!locked) {
> +			locked = 1;
> +			down_read(&mm->mmap_sem);
> +			vma = find_vma(mm, nstart);
> +		} else if (nstart >= vma->vm_end)
> +			vma = vma->vm_next;
> +		if (!vma || vma->vm_start >= end)
> +			break;
> +		/*
> +		 * Set [nstart; nend) to intersection of desired address
> +		 * range with the first VMA. Also, skip undesirable VMA types.
> +		 */
> +		nend = min(end, vma->vm_end);
> +		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
> +			continue;
> +		if (nstart < vma->vm_start)
> +			nstart = vma->vm_start;
> +		/*
> +		 * Now fault in a range of pages. populate_vma_page_range()
> +		 * double checks the vma flags, so that it won't mlock pages
> +		 * if the vma was already munlocked.
> +		 */
> +		ret = populate_vma_page_range(vma, nstart, nend, &locked);
> +		if (ret < 0) {
> +			if (ignore_errors) {
> +				ret = 0;
> +				continue;	/* continue at next VMA */
> +			}
> +			break;
> +		}
> +		nend = nstart + ret * PAGE_SIZE;
> +		ret = 0;
> +	}
> +	if (locked)
> +		up_read(&mm->mmap_sem);
> +	return ret;	/* 0 or negative error code */
> +}
> +
> +/**
> + * get_dump_page() - pin user page in memory while writing it to core dump
> + * @addr: user address
> + *
> + * Returns struct page pointer of user page pinned for dump,
> + * to be freed afterwards by put_page().
> + *
> + * Returns NULL on any kind of failure - a hole must then be inserted into
> + * the corefile, to preserve alignment with its headers; and also returns
> + * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
> + * allowing a hole to be left in the corefile to save diskspace.
> + *
> + * Called without mmap_sem, but after all other threads have been killed.
> + */
> +#ifdef CONFIG_ELF_CORE
> +struct page *get_dump_page(unsigned long addr)
> +{
> +	struct vm_area_struct *vma;
> +	struct page *page;
> +
> +	if (__get_user_pages(current, current->mm, addr, 1,
> +			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
> +			     NULL) < 1)
> +		return NULL;
> +	flush_cache_page(vma, addr, page_to_pfn(page));
> +	return page;
> +}
> +#endif /* CONFIG_ELF_CORE */
> +
> +#else /* CONFIG_MMU */
> +static long __get_user_pages_locked(struct task_struct *tsk,
> +		struct mm_struct *mm, unsigned long start,
> +		unsigned long nr_pages, struct page **pages,
> +		struct vm_area_struct **vmas, int *locked,
> +		unsigned int foll_flags)
> +{
> +	struct vm_area_struct *vma;
> +	unsigned long vm_flags;
> +	int i;
> +
> +	/* calculate required read or write permissions.
> +	 * If FOLL_FORCE is set, we only require the "MAY" flags.
> +	 */
> +	vm_flags  = (foll_flags & FOLL_WRITE) ?
> +			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
> +	vm_flags &= (foll_flags & FOLL_FORCE) ?
> +			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
> +
> +	for (i = 0; i < nr_pages; i++) {
> +		vma = find_vma(mm, start);
> +		if (!vma)
> +			goto finish_or_fault;
> +
> +		/* protect what we can, including chardevs */
> +		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
> +		    !(vm_flags & vma->vm_flags))
> +			goto finish_or_fault;
> +
> +		if (pages) {
> +			pages[i] = virt_to_page(start);
> +			if (pages[i])
> +				get_page(pages[i]);
> +		}
> +		if (vmas)
> +			vmas[i] = vma;
> +		start = (start + PAGE_SIZE) & PAGE_MASK;
> +	}
> +
> +	return i;
> +
> +finish_or_fault:
> +	return i ? : -EFAULT;
> +}
> +#endif /* !CONFIG_MMU */
> +
>  #if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
>  static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
>  {
> @@ -1416,7 +1530,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
>  {
>  	return nr_pages;
>  }
> -#endif
> +#endif /* CONFIG_CMA */
>  
>  /*
>   * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
> @@ -1502,152 +1616,85 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
>  }
>  EXPORT_SYMBOL(get_user_pages);
>  
> -/**
> - * populate_vma_page_range() -  populate a range of pages in the vma.
> - * @vma:   target vma
> - * @start: start address
> - * @end:   end address
> - * @nonblocking:
> - *
> - * This takes care of mlocking the pages too if VM_LOCKED is set.
> +/*
> + * We can leverage the VM_FAULT_RETRY functionality in the page fault
> + * paths better by using either get_user_pages_locked() or
> + * get_user_pages_unlocked().
>   *
> - * return 0 on success, negative error code on error.
> + * get_user_pages_locked() is suitable to replace the form:
>   *
> - * vma->vm_mm->mmap_sem must be held.
> + *      down_read(&mm->mmap_sem);
> + *      do_something()
> + *      get_user_pages(tsk, mm, ..., pages, NULL);
> + *      up_read(&mm->mmap_sem);
>   *
> - * If @nonblocking is NULL, it may be held for read or write and will
> - * be unperturbed.
> + *  to:
>   *
> - * If @nonblocking is non-NULL, it must held for read only and may be
> - * released.  If it's released, *@nonblocking will be set to 0.
> + *      int locked = 1;
> + *      down_read(&mm->mmap_sem);
> + *      do_something()
> + *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
> + *      if (locked)
> + *          up_read(&mm->mmap_sem);
>   */
> -long populate_vma_page_range(struct vm_area_struct *vma,
> -		unsigned long start, unsigned long end, int *nonblocking)
> +long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> +			   unsigned int gup_flags, struct page **pages,
> +			   int *locked)
>  {
> -	struct mm_struct *mm = vma->vm_mm;
> -	unsigned long nr_pages = (end - start) / PAGE_SIZE;
> -	int gup_flags;
> -
> -	VM_BUG_ON(start & ~PAGE_MASK);
> -	VM_BUG_ON(end   & ~PAGE_MASK);
> -	VM_BUG_ON_VMA(start < vma->vm_start, vma);
> -	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
> -	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> -
> -	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
> -	if (vma->vm_flags & VM_LOCKONFAULT)
> -		gup_flags &= ~FOLL_POPULATE;
> -	/*
> -	 * We want to touch writable mappings with a write fault in order
> -	 * to break COW, except for shared mappings because these don't COW
> -	 * and we would not want to dirty them for nothing.
> -	 */
> -	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
> -		gup_flags |= FOLL_WRITE;
> -
>  	/*
> -	 * We want mlock to succeed for regions that have any permissions
> -	 * other than PROT_NONE.
> +	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> +	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> +	 * vmas.  As there are no users of this flag in this call we simply
> +	 * disallow this option for now.
>  	 */
> -	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
> -		gup_flags |= FOLL_FORCE;
> +	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> +		return -EINVAL;
>  
> -	/*
> -	 * We made sure addr is within a VMA, so the following will
> -	 * not result in a stack expansion that recurses back here.
> -	 */
> -	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
> -				NULL, NULL, nonblocking);
> +	return __get_user_pages_locked(current, current->mm, start, nr_pages,
> +				       pages, NULL, locked,
> +				       gup_flags | FOLL_TOUCH);
>  }
> +EXPORT_SYMBOL(get_user_pages_locked);
>  
>  /*
> - * __mm_populate - populate and/or mlock pages within a range of address space.
> + * get_user_pages_unlocked() is suitable to replace the form:
>   *
> - * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
> - * flags. VMAs must be already marked with the desired vm_flags, and
> - * mmap_sem must not be held.
> + *      down_read(&mm->mmap_sem);
> + *      get_user_pages(tsk, mm, ..., pages, NULL);
> + *      up_read(&mm->mmap_sem);
> + *
> + *  with:
> + *
> + *      get_user_pages_unlocked(tsk, mm, ..., pages);
> + *
> + * It is functionally equivalent to get_user_pages_fast so
> + * get_user_pages_fast should be used instead if specific gup_flags
> + * (e.g. FOLL_FORCE) are not required.
>   */
> -int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> +long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> +			     struct page **pages, unsigned int gup_flags)
>  {
>  	struct mm_struct *mm = current->mm;
> -	unsigned long end, nstart, nend;
> -	struct vm_area_struct *vma = NULL;
> -	int locked = 0;
> -	long ret = 0;
> +	int locked = 1;
> +	long ret;
>  
> -	end = start + len;
> +	/*
> +	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> +	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> +	 * vmas.  As there are no users of this flag in this call we simply
> +	 * disallow this option for now.
> +	 */
> +	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> +		return -EINVAL;
>  
> -	for (nstart = start; nstart < end; nstart = nend) {
> -		/*
> -		 * We want to fault in pages for [nstart; end) address range.
> -		 * Find first corresponding VMA.
> -		 */
> -		if (!locked) {
> -			locked = 1;
> -			down_read(&mm->mmap_sem);
> -			vma = find_vma(mm, nstart);
> -		} else if (nstart >= vma->vm_end)
> -			vma = vma->vm_next;
> -		if (!vma || vma->vm_start >= end)
> -			break;
> -		/*
> -		 * Set [nstart; nend) to intersection of desired address
> -		 * range with the first VMA. Also, skip undesirable VMA types.
> -		 */
> -		nend = min(end, vma->vm_end);
> -		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
> -			continue;
> -		if (nstart < vma->vm_start)
> -			nstart = vma->vm_start;
> -		/*
> -		 * Now fault in a range of pages. populate_vma_page_range()
> -		 * double checks the vma flags, so that it won't mlock pages
> -		 * if the vma was already munlocked.
> -		 */
> -		ret = populate_vma_page_range(vma, nstart, nend, &locked);
> -		if (ret < 0) {
> -			if (ignore_errors) {
> -				ret = 0;
> -				continue;	/* continue at next VMA */
> -			}
> -			break;
> -		}
> -		nend = nstart + ret * PAGE_SIZE;
> -		ret = 0;
> -	}
> +	down_read(&mm->mmap_sem);
> +	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
> +				      &locked, gup_flags | FOLL_TOUCH);
>  	if (locked)
>  		up_read(&mm->mmap_sem);
> -	return ret;	/* 0 or negative error code */
> -}
> -
> -/**
> - * get_dump_page() - pin user page in memory while writing it to core dump
> - * @addr: user address
> - *
> - * Returns struct page pointer of user page pinned for dump,
> - * to be freed afterwards by put_page().
> - *
> - * Returns NULL on any kind of failure - a hole must then be inserted into
> - * the corefile, to preserve alignment with its headers; and also returns
> - * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
> - * allowing a hole to be left in the corefile to save diskspace.
> - *
> - * Called without mmap_sem, but after all other threads have been killed.
> - */
> -#ifdef CONFIG_ELF_CORE
> -struct page *get_dump_page(unsigned long addr)
> -{
> -	struct vm_area_struct *vma;
> -	struct page *page;
> -
> -	if (__get_user_pages(current, current->mm, addr, 1,
> -			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
> -			     NULL) < 1)
> -		return NULL;
> -	flush_cache_page(vma, addr, page_to_pfn(page));
> -	return page;
> +	return ret;
>  }
> -#endif /* CONFIG_ELF_CORE */
> +EXPORT_SYMBOL(get_user_pages_unlocked);
>  
>  /*
>   * Fast GUP
> @@ -1682,7 +1729,7 @@ struct page *get_dump_page(unsigned long addr)
>   *
>   * This code is based heavily on the PowerPC implementation by Nick Piggin.
>   */
> -#ifdef CONFIG_HAVE_FAST_GUP
> +#if defined(CONFIG_MMU) && defined(CONFIG_HAVE_FAST_GUP)
>  #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
>  /*
>   * WARNING: only to be used in the get_user_pages_fast() implementation.
> @@ -2159,6 +2206,12 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>  			return;
>  	} while (pgdp++, addr = next, addr != end);
>  }
> +#else
> +static inline void gup_pgd_range(unsigned long addr, unsigned long end,
> +		unsigned int flags, struct page **pages, int *nr)
> +{
> +}
> +#endif /* CONFIG_HAVE_FAST_GUP */
>  
>  #ifndef gup_fast_permitted
>  /*
> @@ -2167,7 +2220,7 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>   */
>  static bool gup_fast_permitted(unsigned long start, unsigned long end)
>  {
> -	return true;
> +	return IS_ENABLED(CONFIG_HAVE_FAST_GUP) ? true : false;
>  }
>  #endif
>  
> @@ -2176,6 +2229,9 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
>   * the regular GUP.
>   * Note a difference with get_user_pages_fast: this always returns the
>   * number of pages pinned, 0 if no pages were pinned.
> + *
> + * If the architecture does not support this function, simply return with no
> + * pages pinned.
>   */
>  int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  			  struct page **pages)
> @@ -2213,6 +2269,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  
>  	return nr;
>  }
> +EXPORT_SYMBOL_GPL(__get_user_pages_fast);
>  
>  static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
>  				   unsigned int gup_flags, struct page **pages)
> @@ -2295,5 +2352,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
>  
>  	return ret;
>  }
> -
> -#endif /* CONFIG_HAVE_GENERIC_GUP */
> +EXPORT_SYMBOL_GPL(get_user_pages_fast);
> diff --git a/mm/nommu.c b/mm/nommu.c
> index d8c02fbe03b5..07165ad2e548 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -111,94 +111,6 @@ unsigned int kobjsize(const void *objp)
>  	return PAGE_SIZE << compound_order(page);
>  }
>  
> -static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> -		      unsigned long start, unsigned long nr_pages,
> -		      unsigned int foll_flags, struct page **pages,
> -		      struct vm_area_struct **vmas, int *nonblocking)
> -{
> -	struct vm_area_struct *vma;
> -	unsigned long vm_flags;
> -	int i;
> -
> -	/* calculate required read or write permissions.
> -	 * If FOLL_FORCE is set, we only require the "MAY" flags.
> -	 */
> -	vm_flags  = (foll_flags & FOLL_WRITE) ?
> -			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
> -	vm_flags &= (foll_flags & FOLL_FORCE) ?
> -			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
> -
> -	for (i = 0; i < nr_pages; i++) {
> -		vma = find_vma(mm, start);
> -		if (!vma)
> -			goto finish_or_fault;
> -
> -		/* protect what we can, including chardevs */
> -		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
> -		    !(vm_flags & vma->vm_flags))
> -			goto finish_or_fault;
> -
> -		if (pages) {
> -			pages[i] = virt_to_page(start);
> -			if (pages[i])
> -				get_page(pages[i]);
> -		}
> -		if (vmas)
> -			vmas[i] = vma;
> -		start = (start + PAGE_SIZE) & PAGE_MASK;
> -	}
> -
> -	return i;
> -
> -finish_or_fault:
> -	return i ? : -EFAULT;
> -}
> -
> -/*
> - * get a list of pages in an address range belonging to the specified process
> - * and indicate the VMA that covers each page
> - * - this is potentially dodgy as we may end incrementing the page count of a
> - *   slab page or a secondary page from a compound page
> - * - don't permit access to VMAs that don't support it, such as I/O mappings
> - */
> -long get_user_pages(unsigned long start, unsigned long nr_pages,
> -		    unsigned int gup_flags, struct page **pages,
> -		    struct vm_area_struct **vmas)
> -{
> -	return __get_user_pages(current, current->mm, start, nr_pages,
> -				gup_flags, pages, vmas, NULL);
> -}
> -EXPORT_SYMBOL(get_user_pages);
> -
> -long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> -			    unsigned int gup_flags, struct page **pages,
> -			    int *locked)
> -{
> -	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
> -}
> -EXPORT_SYMBOL(get_user_pages_locked);
> -
> -static long __get_user_pages_unlocked(struct task_struct *tsk,
> -			struct mm_struct *mm, unsigned long start,
> -			unsigned long nr_pages, struct page **pages,
> -			unsigned int gup_flags)
> -{
> -	long ret;
> -	down_read(&mm->mmap_sem);
> -	ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
> -				NULL, NULL);
> -	up_read(&mm->mmap_sem);
> -	return ret;
> -}
> -
> -long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> -			     struct page **pages, unsigned int gup_flags)
> -{
> -	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
> -					 pages, gup_flags);
> -}
> -EXPORT_SYMBOL(get_user_pages_unlocked);
> -
>  /**
>   * follow_pfn - look up PFN at a user virtual address
>   * @vma: memory mapping
> diff --git a/mm/util.c b/mm/util.c
> index 91682a2090ee..d58f5b0eb669 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -300,53 +300,6 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>  }
>  #endif
>  
> -/*
> - * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
> - * back to the regular GUP.
> - * Note a difference with get_user_pages_fast: this always returns the
> - * number of pages pinned, 0 if no pages were pinned.
> - * If the architecture does not support this function, simply return with no
> - * pages pinned.
> - */
> -int __weak __get_user_pages_fast(unsigned long start,
> -				 int nr_pages, int write, struct page **pages)
> -{
> -	return 0;
> -}
> -EXPORT_SYMBOL_GPL(__get_user_pages_fast);
> -
> -/**
> - * get_user_pages_fast() - pin user pages in memory
> - * @start:	starting user address
> - * @nr_pages:	number of pages from start to pin
> - * @gup_flags:	flags modifying pin behaviour
> - * @pages:	array that receives pointers to the pages pinned.
> - *		Should be at least nr_pages long.
> - *
> - * get_user_pages_fast provides equivalent functionality to get_user_pages,
> - * operating on current and current->mm, with force=0 and vma=NULL. However
> - * unlike get_user_pages, it must be called without mmap_sem held.
> - *
> - * get_user_pages_fast may take mmap_sem and page table locks, so no
> - * assumptions can be made about lack of locking. get_user_pages_fast is to be
> - * implemented in a way that is advantageous (vs get_user_pages()) when the
> - * user memory area is already faulted in and present in ptes. However if the
> - * pages have to be faulted in, it may turn out to be slightly slower so
> - * callers need to carefully consider what to use. On many architectures,
> - * get_user_pages_fast simply falls back to get_user_pages.
> - *
> - * Return: number of pages pinned. This may be fewer than the number
> - * requested. If nr_pages is 0 or negative, returns 0. If no pages
> - * were pinned, returns -errno.
> - */
> -int __weak get_user_pages_fast(unsigned long start,
> -				int nr_pages, unsigned int gup_flags,
> -				struct page **pages)
> -{
> -	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
> -}
> -EXPORT_SYMBOL_GPL(get_user_pages_fast);
> -
>  unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
>  	unsigned long len, unsigned long prot,
>  	unsigned long flag, unsigned long pgoff)
> 

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[John Hubbard]

On 6/1/19 12:49 AM, Christoph Hellwig wrote:
> Always build mm/gup.c, and move the nommu versions and replace the
> separate stubs for various functions by the default ones, with the _fast
> version always falling back to the slow path because gup_fast_permitted
> always returns false now if HAVE_FAST_GUP is not set, and we use the
> nommu version of __get_user_pages while keeping all the wrappers common.
> 
> This also ensures the new put_user_pages* helpers are available for
> nommu, as those are currently missing, which would create a problem as
> soon as we actually grew users for it.
> 

Hi Christoph,

Thanks for fixing up the nommu case. And the patchset overall is a huge
relief to see, because I'd filed those arches under the "despair" category
for the gup conversions. :)

I started reviewing this one patch, and it's kind of messy figuring out 
if the code motion preserves everything because of
all the consolidation from other places, plus having to move things in
and out of the ifdef blocks.  So I figured I'd check and see if this is
going to make it past RFC status soon, and if it's going before or after
Ira's recent RFC ("RDMA/FS DAX truncate proposal").


thanks,
-- 
John Hubbard
NVIDIA

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  mm/Kconfig  |   1 +
>  mm/Makefile |   4 +-
>  mm/gup.c    | 476 +++++++++++++++++++++++++++++-----------------------
>  mm/nommu.c  |  88 ----------
>  mm/util.c   |  47 ------
>  5 files changed, 269 insertions(+), 347 deletions(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 98dffb0f2447..5c41409557da 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -133,6 +133,7 @@ config HAVE_MEMBLOCK_PHYS_MAP
>  	bool
>  
>  config HAVE_FAST_GUP
> +	depends on MMU
>  	bool
>  
>  config ARCH_KEEP_MEMBLOCK
> diff --git a/mm/Makefile b/mm/Makefile
> index ac5e5ba78874..dc0746ca1109 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -22,7 +22,7 @@ KCOV_INSTRUMENT_mmzone.o := n
>  KCOV_INSTRUMENT_vmstat.o := n
>  
>  mmu-y			:= nommu.o
> -mmu-$(CONFIG_MMU)	:= gup.o highmem.o memory.o mincore.o \
> +mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
>  			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
>  			   msync.o page_vma_mapped.o pagewalk.o \
>  			   pgtable-generic.o rmap.o vmalloc.o
> @@ -39,7 +39,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
>  			   mm_init.o mmu_context.o percpu.o slab_common.o \
>  			   compaction.o vmacache.o \
>  			   interval_tree.o list_lru.o workingset.o \
> -			   debug.o $(mmu-y)
> +			   debug.o gup.o $(mmu-y)
>  
>  # Give 'page_alloc' its own module-parameter namespace
>  page-alloc-y := page_alloc.o
> diff --git a/mm/gup.c b/mm/gup.c
> index a24f52292c7f..c8da7764de9c 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -134,6 +134,7 @@ void put_user_pages(struct page **pages, unsigned long npages)
>  }
>  EXPORT_SYMBOL(put_user_pages);
>  
> +#ifdef CONFIG_MMU
>  static struct page *no_page_table(struct vm_area_struct *vma,
>  		unsigned int flags)
>  {
> @@ -1099,86 +1100,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
>  	return pages_done;
>  }
>  
> -/*
> - * We can leverage the VM_FAULT_RETRY functionality in the page fault
> - * paths better by using either get_user_pages_locked() or
> - * get_user_pages_unlocked().
> - *
> - * get_user_pages_locked() is suitable to replace the form:
> - *
> - *      down_read(&mm->mmap_sem);
> - *      do_something()
> - *      get_user_pages(tsk, mm, ..., pages, NULL);
> - *      up_read(&mm->mmap_sem);
> - *
> - *  to:
> - *
> - *      int locked = 1;
> - *      down_read(&mm->mmap_sem);
> - *      do_something()
> - *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
> - *      if (locked)
> - *          up_read(&mm->mmap_sem);
> - */
> -long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> -			   unsigned int gup_flags, struct page **pages,
> -			   int *locked)
> -{
> -	/*
> -	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> -	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> -	 * vmas.  As there are no users of this flag in this call we simply
> -	 * disallow this option for now.
> -	 */
> -	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> -		return -EINVAL;
> -
> -	return __get_user_pages_locked(current, current->mm, start, nr_pages,
> -				       pages, NULL, locked,
> -				       gup_flags | FOLL_TOUCH);
> -}
> -EXPORT_SYMBOL(get_user_pages_locked);
> -
> -/*
> - * get_user_pages_unlocked() is suitable to replace the form:
> - *
> - *      down_read(&mm->mmap_sem);
> - *      get_user_pages(tsk, mm, ..., pages, NULL);
> - *      up_read(&mm->mmap_sem);
> - *
> - *  with:
> - *
> - *      get_user_pages_unlocked(tsk, mm, ..., pages);
> - *
> - * It is functionally equivalent to get_user_pages_fast so
> - * get_user_pages_fast should be used instead if specific gup_flags
> - * (e.g. FOLL_FORCE) are not required.
> - */
> -long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> -			     struct page **pages, unsigned int gup_flags)
> -{
> -	struct mm_struct *mm = current->mm;
> -	int locked = 1;
> -	long ret;
> -
> -	/*
> -	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> -	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> -	 * vmas.  As there are no users of this flag in this call we simply
> -	 * disallow this option for now.
> -	 */
> -	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> -		return -EINVAL;
> -
> -	down_read(&mm->mmap_sem);
> -	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
> -				      &locked, gup_flags | FOLL_TOUCH);
> -	if (locked)
> -		up_read(&mm->mmap_sem);
> -	return ret;
> -}
> -EXPORT_SYMBOL(get_user_pages_unlocked);
> -
>  /*
>   * get_user_pages_remote() - pin user pages in memory
>   * @tsk:	the task_struct to use for page fault accounting, or
> @@ -1255,6 +1176,199 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
>  }
>  EXPORT_SYMBOL(get_user_pages_remote);
>  
> +/**
> + * populate_vma_page_range() -  populate a range of pages in the vma.
> + * @vma:   target vma
> + * @start: start address
> + * @end:   end address
> + * @nonblocking:
> + *
> + * This takes care of mlocking the pages too if VM_LOCKED is set.
> + *
> + * return 0 on success, negative error code on error.
> + *
> + * vma->vm_mm->mmap_sem must be held.
> + *
> + * If @nonblocking is NULL, it may be held for read or write and will
> + * be unperturbed.
> + *
> + * If @nonblocking is non-NULL, it must held for read only and may be
> + * released.  If it's released, *@nonblocking will be set to 0.
> + */
> +long populate_vma_page_range(struct vm_area_struct *vma,
> +		unsigned long start, unsigned long end, int *nonblocking)
> +{
> +	struct mm_struct *mm = vma->vm_mm;
> +	unsigned long nr_pages = (end - start) / PAGE_SIZE;
> +	int gup_flags;
> +
> +	VM_BUG_ON(start & ~PAGE_MASK);
> +	VM_BUG_ON(end   & ~PAGE_MASK);
> +	VM_BUG_ON_VMA(start < vma->vm_start, vma);
> +	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
> +	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> +
> +	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
> +	if (vma->vm_flags & VM_LOCKONFAULT)
> +		gup_flags &= ~FOLL_POPULATE;
> +	/*
> +	 * We want to touch writable mappings with a write fault in order
> +	 * to break COW, except for shared mappings because these don't COW
> +	 * and we would not want to dirty them for nothing.
> +	 */
> +	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
> +		gup_flags |= FOLL_WRITE;
> +
> +	/*
> +	 * We want mlock to succeed for regions that have any permissions
> +	 * other than PROT_NONE.
> +	 */
> +	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
> +		gup_flags |= FOLL_FORCE;
> +
> +	/*
> +	 * We made sure addr is within a VMA, so the following will
> +	 * not result in a stack expansion that recurses back here.
> +	 */
> +	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
> +				NULL, NULL, nonblocking);
> +}
> +
> +/*
> + * __mm_populate - populate and/or mlock pages within a range of address space.
> + *
> + * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
> + * flags. VMAs must be already marked with the desired vm_flags, and
> + * mmap_sem must not be held.
> + */
> +int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> +{
> +	struct mm_struct *mm = current->mm;
> +	unsigned long end, nstart, nend;
> +	struct vm_area_struct *vma = NULL;
> +	int locked = 0;
> +	long ret = 0;
> +
> +	end = start + len;
> +
> +	for (nstart = start; nstart < end; nstart = nend) {
> +		/*
> +		 * We want to fault in pages for [nstart; end) address range.
> +		 * Find first corresponding VMA.
> +		 */
> +		if (!locked) {
> +			locked = 1;
> +			down_read(&mm->mmap_sem);
> +			vma = find_vma(mm, nstart);
> +		} else if (nstart >= vma->vm_end)
> +			vma = vma->vm_next;
> +		if (!vma || vma->vm_start >= end)
> +			break;
> +		/*
> +		 * Set [nstart; nend) to intersection of desired address
> +		 * range with the first VMA. Also, skip undesirable VMA types.
> +		 */
> +		nend = min(end, vma->vm_end);
> +		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
> +			continue;
> +		if (nstart < vma->vm_start)
> +			nstart = vma->vm_start;
> +		/*
> +		 * Now fault in a range of pages. populate_vma_page_range()
> +		 * double checks the vma flags, so that it won't mlock pages
> +		 * if the vma was already munlocked.
> +		 */
> +		ret = populate_vma_page_range(vma, nstart, nend, &locked);
> +		if (ret < 0) {
> +			if (ignore_errors) {
> +				ret = 0;
> +				continue;	/* continue at next VMA */
> +			}
> +			break;
> +		}
> +		nend = nstart + ret * PAGE_SIZE;
> +		ret = 0;
> +	}
> +	if (locked)
> +		up_read(&mm->mmap_sem);
> +	return ret;	/* 0 or negative error code */
> +}
> +
> +/**
> + * get_dump_page() - pin user page in memory while writing it to core dump
> + * @addr: user address
> + *
> + * Returns struct page pointer of user page pinned for dump,
> + * to be freed afterwards by put_page().
> + *
> + * Returns NULL on any kind of failure - a hole must then be inserted into
> + * the corefile, to preserve alignment with its headers; and also returns
> + * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
> + * allowing a hole to be left in the corefile to save diskspace.
> + *
> + * Called without mmap_sem, but after all other threads have been killed.
> + */
> +#ifdef CONFIG_ELF_CORE
> +struct page *get_dump_page(unsigned long addr)
> +{
> +	struct vm_area_struct *vma;
> +	struct page *page;
> +
> +	if (__get_user_pages(current, current->mm, addr, 1,
> +			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
> +			     NULL) < 1)
> +		return NULL;
> +	flush_cache_page(vma, addr, page_to_pfn(page));
> +	return page;
> +}
> +#endif /* CONFIG_ELF_CORE */
> +
> +#else /* CONFIG_MMU */
> +static long __get_user_pages_locked(struct task_struct *tsk,
> +		struct mm_struct *mm, unsigned long start,
> +		unsigned long nr_pages, struct page **pages,
> +		struct vm_area_struct **vmas, int *locked,
> +		unsigned int foll_flags)
> +{
> +	struct vm_area_struct *vma;
> +	unsigned long vm_flags;
> +	int i;
> +
> +	/* calculate required read or write permissions.
> +	 * If FOLL_FORCE is set, we only require the "MAY" flags.
> +	 */
> +	vm_flags  = (foll_flags & FOLL_WRITE) ?
> +			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
> +	vm_flags &= (foll_flags & FOLL_FORCE) ?
> +			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
> +
> +	for (i = 0; i < nr_pages; i++) {
> +		vma = find_vma(mm, start);
> +		if (!vma)
> +			goto finish_or_fault;
> +
> +		/* protect what we can, including chardevs */
> +		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
> +		    !(vm_flags & vma->vm_flags))
> +			goto finish_or_fault;
> +
> +		if (pages) {
> +			pages[i] = virt_to_page(start);
> +			if (pages[i])
> +				get_page(pages[i]);
> +		}
> +		if (vmas)
> +			vmas[i] = vma;
> +		start = (start + PAGE_SIZE) & PAGE_MASK;
> +	}
> +
> +	return i;
> +
> +finish_or_fault:
> +	return i ? : -EFAULT;
> +}
> +#endif /* !CONFIG_MMU */
> +
>  #if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
>  static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
>  {
> @@ -1416,7 +1530,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
>  {
>  	return nr_pages;
>  }
> -#endif
> +#endif /* CONFIG_CMA */
>  
>  /*
>   * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
> @@ -1502,152 +1616,85 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
>  }
>  EXPORT_SYMBOL(get_user_pages);
>  
> -/**
> - * populate_vma_page_range() -  populate a range of pages in the vma.
> - * @vma:   target vma
> - * @start: start address
> - * @end:   end address
> - * @nonblocking:
> - *
> - * This takes care of mlocking the pages too if VM_LOCKED is set.
> +/*
> + * We can leverage the VM_FAULT_RETRY functionality in the page fault
> + * paths better by using either get_user_pages_locked() or
> + * get_user_pages_unlocked().
>   *
> - * return 0 on success, negative error code on error.
> + * get_user_pages_locked() is suitable to replace the form:
>   *
> - * vma->vm_mm->mmap_sem must be held.
> + *      down_read(&mm->mmap_sem);
> + *      do_something()
> + *      get_user_pages(tsk, mm, ..., pages, NULL);
> + *      up_read(&mm->mmap_sem);
>   *
> - * If @nonblocking is NULL, it may be held for read or write and will
> - * be unperturbed.
> + *  to:
>   *
> - * If @nonblocking is non-NULL, it must held for read only and may be
> - * released.  If it's released, *@nonblocking will be set to 0.
> + *      int locked = 1;
> + *      down_read(&mm->mmap_sem);
> + *      do_something()
> + *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
> + *      if (locked)
> + *          up_read(&mm->mmap_sem);
>   */
> -long populate_vma_page_range(struct vm_area_struct *vma,
> -		unsigned long start, unsigned long end, int *nonblocking)
> +long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> +			   unsigned int gup_flags, struct page **pages,
> +			   int *locked)
>  {
> -	struct mm_struct *mm = vma->vm_mm;
> -	unsigned long nr_pages = (end - start) / PAGE_SIZE;
> -	int gup_flags;
> -
> -	VM_BUG_ON(start & ~PAGE_MASK);
> -	VM_BUG_ON(end   & ~PAGE_MASK);
> -	VM_BUG_ON_VMA(start < vma->vm_start, vma);
> -	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
> -	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> -
> -	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
> -	if (vma->vm_flags & VM_LOCKONFAULT)
> -		gup_flags &= ~FOLL_POPULATE;
> -	/*
> -	 * We want to touch writable mappings with a write fault in order
> -	 * to break COW, except for shared mappings because these don't COW
> -	 * and we would not want to dirty them for nothing.
> -	 */
> -	if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
> -		gup_flags |= FOLL_WRITE;
> -
>  	/*
> -	 * We want mlock to succeed for regions that have any permissions
> -	 * other than PROT_NONE.
> +	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> +	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> +	 * vmas.  As there are no users of this flag in this call we simply
> +	 * disallow this option for now.
>  	 */
> -	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
> -		gup_flags |= FOLL_FORCE;
> +	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> +		return -EINVAL;
>  
> -	/*
> -	 * We made sure addr is within a VMA, so the following will
> -	 * not result in a stack expansion that recurses back here.
> -	 */
> -	return __get_user_pages(current, mm, start, nr_pages, gup_flags,
> -				NULL, NULL, nonblocking);
> +	return __get_user_pages_locked(current, current->mm, start, nr_pages,
> +				       pages, NULL, locked,
> +				       gup_flags | FOLL_TOUCH);
>  }
> +EXPORT_SYMBOL(get_user_pages_locked);
>  
>  /*
> - * __mm_populate - populate and/or mlock pages within a range of address space.
> + * get_user_pages_unlocked() is suitable to replace the form:
>   *
> - * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
> - * flags. VMAs must be already marked with the desired vm_flags, and
> - * mmap_sem must not be held.
> + *      down_read(&mm->mmap_sem);
> + *      get_user_pages(tsk, mm, ..., pages, NULL);
> + *      up_read(&mm->mmap_sem);
> + *
> + *  with:
> + *
> + *      get_user_pages_unlocked(tsk, mm, ..., pages);
> + *
> + * It is functionally equivalent to get_user_pages_fast so
> + * get_user_pages_fast should be used instead if specific gup_flags
> + * (e.g. FOLL_FORCE) are not required.
>   */
> -int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> +long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> +			     struct page **pages, unsigned int gup_flags)
>  {
>  	struct mm_struct *mm = current->mm;
> -	unsigned long end, nstart, nend;
> -	struct vm_area_struct *vma = NULL;
> -	int locked = 0;
> -	long ret = 0;
> +	int locked = 1;
> +	long ret;
>  
> -	end = start + len;
> +	/*
> +	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
> +	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
> +	 * vmas.  As there are no users of this flag in this call we simply
> +	 * disallow this option for now.
> +	 */
> +	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
> +		return -EINVAL;
>  
> -	for (nstart = start; nstart < end; nstart = nend) {
> -		/*
> -		 * We want to fault in pages for [nstart; end) address range.
> -		 * Find first corresponding VMA.
> -		 */
> -		if (!locked) {
> -			locked = 1;
> -			down_read(&mm->mmap_sem);
> -			vma = find_vma(mm, nstart);
> -		} else if (nstart >= vma->vm_end)
> -			vma = vma->vm_next;
> -		if (!vma || vma->vm_start >= end)
> -			break;
> -		/*
> -		 * Set [nstart; nend) to intersection of desired address
> -		 * range with the first VMA. Also, skip undesirable VMA types.
> -		 */
> -		nend = min(end, vma->vm_end);
> -		if (vma->vm_flags & (VM_IO | VM_PFNMAP))
> -			continue;
> -		if (nstart < vma->vm_start)
> -			nstart = vma->vm_start;
> -		/*
> -		 * Now fault in a range of pages. populate_vma_page_range()
> -		 * double checks the vma flags, so that it won't mlock pages
> -		 * if the vma was already munlocked.
> -		 */
> -		ret = populate_vma_page_range(vma, nstart, nend, &locked);
> -		if (ret < 0) {
> -			if (ignore_errors) {
> -				ret = 0;
> -				continue;	/* continue at next VMA */
> -			}
> -			break;
> -		}
> -		nend = nstart + ret * PAGE_SIZE;
> -		ret = 0;
> -	}
> +	down_read(&mm->mmap_sem);
> +	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
> +				      &locked, gup_flags | FOLL_TOUCH);
>  	if (locked)
>  		up_read(&mm->mmap_sem);
> -	return ret;	/* 0 or negative error code */
> -}
> -
> -/**
> - * get_dump_page() - pin user page in memory while writing it to core dump
> - * @addr: user address
> - *
> - * Returns struct page pointer of user page pinned for dump,
> - * to be freed afterwards by put_page().
> - *
> - * Returns NULL on any kind of failure - a hole must then be inserted into
> - * the corefile, to preserve alignment with its headers; and also returns
> - * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
> - * allowing a hole to be left in the corefile to save diskspace.
> - *
> - * Called without mmap_sem, but after all other threads have been killed.
> - */
> -#ifdef CONFIG_ELF_CORE
> -struct page *get_dump_page(unsigned long addr)
> -{
> -	struct vm_area_struct *vma;
> -	struct page *page;
> -
> -	if (__get_user_pages(current, current->mm, addr, 1,
> -			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
> -			     NULL) < 1)
> -		return NULL;
> -	flush_cache_page(vma, addr, page_to_pfn(page));
> -	return page;
> +	return ret;
>  }
> -#endif /* CONFIG_ELF_CORE */
> +EXPORT_SYMBOL(get_user_pages_unlocked);
>  
>  /*
>   * Fast GUP
> @@ -1682,7 +1729,7 @@ struct page *get_dump_page(unsigned long addr)
>   *
>   * This code is based heavily on the PowerPC implementation by Nick Piggin.
>   */
> -#ifdef CONFIG_HAVE_FAST_GUP
> +#if defined(CONFIG_MMU) && defined(CONFIG_HAVE_FAST_GUP)
>  #ifdef CONFIG_GUP_GET_PTE_LOW_HIGH
>  /*
>   * WARNING: only to be used in the get_user_pages_fast() implementation.
> @@ -2159,6 +2206,12 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>  			return;
>  	} while (pgdp++, addr = next, addr != end);
>  }
> +#else
> +static inline void gup_pgd_range(unsigned long addr, unsigned long end,
> +		unsigned int flags, struct page **pages, int *nr)
> +{
> +}
> +#endif /* CONFIG_HAVE_FAST_GUP */
>  
>  #ifndef gup_fast_permitted
>  /*
> @@ -2167,7 +2220,7 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>   */
>  static bool gup_fast_permitted(unsigned long start, unsigned long end)
>  {
> -	return true;
> +	return IS_ENABLED(CONFIG_HAVE_FAST_GUP) ? true : false;
>  }
>  #endif
>  
> @@ -2176,6 +2229,9 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
>   * the regular GUP.
>   * Note a difference with get_user_pages_fast: this always returns the
>   * number of pages pinned, 0 if no pages were pinned.
> + *
> + * If the architecture does not support this function, simply return with no
> + * pages pinned.
>   */
>  int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  			  struct page **pages)
> @@ -2213,6 +2269,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  
>  	return nr;
>  }
> +EXPORT_SYMBOL_GPL(__get_user_pages_fast);
>  
>  static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
>  				   unsigned int gup_flags, struct page **pages)
> @@ -2295,5 +2352,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
>  
>  	return ret;
>  }
> -
> -#endif /* CONFIG_HAVE_GENERIC_GUP */
> +EXPORT_SYMBOL_GPL(get_user_pages_fast);
> diff --git a/mm/nommu.c b/mm/nommu.c
> index d8c02fbe03b5..07165ad2e548 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -111,94 +111,6 @@ unsigned int kobjsize(const void *objp)
>  	return PAGE_SIZE << compound_order(page);
>  }
>  
> -static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> -		      unsigned long start, unsigned long nr_pages,
> -		      unsigned int foll_flags, struct page **pages,
> -		      struct vm_area_struct **vmas, int *nonblocking)
> -{
> -	struct vm_area_struct *vma;
> -	unsigned long vm_flags;
> -	int i;
> -
> -	/* calculate required read or write permissions.
> -	 * If FOLL_FORCE is set, we only require the "MAY" flags.
> -	 */
> -	vm_flags  = (foll_flags & FOLL_WRITE) ?
> -			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
> -	vm_flags &= (foll_flags & FOLL_FORCE) ?
> -			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
> -
> -	for (i = 0; i < nr_pages; i++) {
> -		vma = find_vma(mm, start);
> -		if (!vma)
> -			goto finish_or_fault;
> -
> -		/* protect what we can, including chardevs */
> -		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
> -		    !(vm_flags & vma->vm_flags))
> -			goto finish_or_fault;
> -
> -		if (pages) {
> -			pages[i] = virt_to_page(start);
> -			if (pages[i])
> -				get_page(pages[i]);
> -		}
> -		if (vmas)
> -			vmas[i] = vma;
> -		start = (start + PAGE_SIZE) & PAGE_MASK;
> -	}
> -
> -	return i;
> -
> -finish_or_fault:
> -	return i ? : -EFAULT;
> -}
> -
> -/*
> - * get a list of pages in an address range belonging to the specified process
> - * and indicate the VMA that covers each page
> - * - this is potentially dodgy as we may end incrementing the page count of a
> - *   slab page or a secondary page from a compound page
> - * - don't permit access to VMAs that don't support it, such as I/O mappings
> - */
> -long get_user_pages(unsigned long start, unsigned long nr_pages,
> -		    unsigned int gup_flags, struct page **pages,
> -		    struct vm_area_struct **vmas)
> -{
> -	return __get_user_pages(current, current->mm, start, nr_pages,
> -				gup_flags, pages, vmas, NULL);
> -}
> -EXPORT_SYMBOL(get_user_pages);
> -
> -long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> -			    unsigned int gup_flags, struct page **pages,
> -			    int *locked)
> -{
> -	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
> -}
> -EXPORT_SYMBOL(get_user_pages_locked);
> -
> -static long __get_user_pages_unlocked(struct task_struct *tsk,
> -			struct mm_struct *mm, unsigned long start,
> -			unsigned long nr_pages, struct page **pages,
> -			unsigned int gup_flags)
> -{
> -	long ret;
> -	down_read(&mm->mmap_sem);
> -	ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages,
> -				NULL, NULL);
> -	up_read(&mm->mmap_sem);
> -	return ret;
> -}
> -
> -long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> -			     struct page **pages, unsigned int gup_flags)
> -{
> -	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
> -					 pages, gup_flags);
> -}
> -EXPORT_SYMBOL(get_user_pages_unlocked);
> -
>  /**
>   * follow_pfn - look up PFN at a user virtual address
>   * @vma: memory mapping
> diff --git a/mm/util.c b/mm/util.c
> index 91682a2090ee..d58f5b0eb669 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -300,53 +300,6 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>  }
>  #endif
>  
> -/*
> - * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
> - * back to the regular GUP.
> - * Note a difference with get_user_pages_fast: this always returns the
> - * number of pages pinned, 0 if no pages were pinned.
> - * If the architecture does not support this function, simply return with no
> - * pages pinned.
> - */
> -int __weak __get_user_pages_fast(unsigned long start,
> -				 int nr_pages, int write, struct page **pages)
> -{
> -	return 0;
> -}
> -EXPORT_SYMBOL_GPL(__get_user_pages_fast);
> -
> -/**
> - * get_user_pages_fast() - pin user pages in memory
> - * @start:	starting user address
> - * @nr_pages:	number of pages from start to pin
> - * @gup_flags:	flags modifying pin behaviour
> - * @pages:	array that receives pointers to the pages pinned.
> - *		Should be at least nr_pages long.
> - *
> - * get_user_pages_fast provides equivalent functionality to get_user_pages,
> - * operating on current and current->mm, with force=0 and vma=NULL. However
> - * unlike get_user_pages, it must be called without mmap_sem held.
> - *
> - * get_user_pages_fast may take mmap_sem and page table locks, so no
> - * assumptions can be made about lack of locking. get_user_pages_fast is to be
> - * implemented in a way that is advantageous (vs get_user_pages()) when the
> - * user memory area is already faulted in and present in ptes. However if the
> - * pages have to be faulted in, it may turn out to be slightly slower so
> - * callers need to carefully consider what to use. On many architectures,
> - * get_user_pages_fast simply falls back to get_user_pages.
> - *
> - * Return: number of pages pinned. This may be fewer than the number
> - * requested. If nr_pages is 0 or negative, returns 0. If no pages
> - * were pinned, returns -errno.
> - */
> -int __weak get_user_pages_fast(unsigned long start,
> -				int nr_pages, unsigned int gup_flags,
> -				struct page **pages)
> -{
> -	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
> -}
> -EXPORT_SYMBOL_GPL(get_user_pages_fast);
> -
>  unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
>  	unsigned long len, unsigned long prot,
>  	unsigned long flag, unsigned long pgoff)
> 

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[Christoph Hellwig]

On Wed, Jun 05, 2019 at 11:01:17PM -0700, John Hubbard wrote:
> I started reviewing this one patch, and it's kind of messy figuring out 
> if the code motion preserves everything because of
> all the consolidation from other places, plus having to move things in
> and out of the ifdef blocks.  So I figured I'd check and see if this is
> going to make it past RFC status soon, and if it's going before or after
> Ira's recent RFC ("RDMA/FS DAX truncate proposal").

I don't like the huge moves either, but I can't really think of any
better way to do it.  Proposals welcome, though.

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[Christoph Hellwig]

On Wed, Jun 05, 2019 at 11:01:17PM -0700, John Hubbard wrote:
> I started reviewing this one patch, and it's kind of messy figuring out 
> if the code motion preserves everything because of
> all the consolidation from other places, plus having to move things in
> and out of the ifdef blocks.  So I figured I'd check and see if this is
> going to make it past RFC status soon, and if it's going before or after
> Ira's recent RFC ("RDMA/FS DAX truncate proposal").

I don't like the huge moves either, but I can't really think of any
better way to do it.  Proposals welcome, though.

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[Christoph Hellwig]

On Wed, Jun 05, 2019 at 11:01:17PM -0700, John Hubbard wrote:
> I started reviewing this one patch, and it's kind of messy figuring out 
> if the code motion preserves everything because of
> all the consolidation from other places, plus having to move things in
> and out of the ifdef blocks.  So I figured I'd check and see if this is
> going to make it past RFC status soon, and if it's going before or after
> Ira's recent RFC ("RDMA/FS DAX truncate proposal").

I don't like the huge moves either, but I can't really think of any
better way to do it.  Proposals welcome, though.

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[John Hubbard]

On 6/5/19 11:20 PM, Christoph Hellwig wrote:
> On Wed, Jun 05, 2019 at 11:01:17PM -0700, John Hubbard wrote:
>> I started reviewing this one patch, and it's kind of messy figuring out
>> if the code motion preserves everything because of
>> all the consolidation from other places, plus having to move things in
>> and out of the ifdef blocks.  So I figured I'd check and see if this is
>> going to make it past RFC status soon, and if it's going before or after
>> Ira's recent RFC ("RDMA/FS DAX truncate proposal").
> 
> I don't like the huge moves either, but I can't really think of any
> better way to do it.  Proposals welcome, though.
> 

One way would be to do it in two patches:

1) Move the code into gup.c, maybe at the bottom. Surround each function
or group of functions by whatever ifdefs they need.

2) Move code out of the bottom of gup.c, into the final location.

...but I'm not certain that will be that much better. In the spirit of
not creating gratuitous work for others, I could try it out and send
out something if it looks like it's noticeably easier to verify/review.

thanks,
-- 
John Hubbard
NVIDIA

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[John Hubbard]

On 6/5/19 11:20 PM, Christoph Hellwig wrote:
> On Wed, Jun 05, 2019 at 11:01:17PM -0700, John Hubbard wrote:
>> I started reviewing this one patch, and it's kind of messy figuring out
>> if the code motion preserves everything because of
>> all the consolidation from other places, plus having to move things in
>> and out of the ifdef blocks.  So I figured I'd check and see if this is
>> going to make it past RFC status soon, and if it's going before or after
>> Ira's recent RFC ("RDMA/FS DAX truncate proposal").
> 
> I don't like the huge moves either, but I can't really think of any
> better way to do it.  Proposals welcome, though.
> 

One way would be to do it in two patches:

1) Move the code into gup.c, maybe at the bottom. Surround each function
or group of functions by whatever ifdefs they need.

2) Move code out of the bottom of gup.c, into the final location.

...but I'm not certain that will be that much better. In the spirit of
not creating gratuitous work for others, I could try it out and send
out something if it looks like it's noticeably easier to verify/review.

thanks,
-- 
John Hubbard
NVIDIA

Re: [PATCH 12/16] mm: consolidate the get_user_pages* implementations

[John Hubbard]

On 6/5/19 11:20 PM, Christoph Hellwig wrote:
> On Wed, Jun 05, 2019 at 11:01:17PM -0700, John Hubbard wrote:
>> I started reviewing this one patch, and it's kind of messy figuring out
>> if the code motion preserves everything because of
>> all the consolidation from other places, plus having to move things in
>> and out of the ifdef blocks.  So I figured I'd check and see if this is
>> going to make it past RFC status soon, and if it's going before or after
>> Ira's recent RFC ("RDMA/FS DAX truncate proposal").
> 
> I don't like the huge moves either, but I can't really think of any
> better way to do it.  Proposals welcome, though.
> 

One way would be to do it in two patches:

1) Move the code into gup.c, maybe at the bottom. Surround each function
or group of functions by whatever ifdefs they need.

2) Move code out of the bottom of gup.c, into the final location.

...but I'm not certain that will be that much better. In the spirit of
not creating gratuitous work for others, I could try it out and send
out something if it looks like it's noticeably easier to verify/review.

thanks,
-- 
John Hubbard
NVIDIA

[PATCH 13/16] mm: validate get_user_pages_fast flags

[Christoph Hellwig]

We can only deal with FOLL_WRITE and/or FOLL_LONGTERM in
get_user_pages_fast, so reject all other flags.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index c8da7764de9c..53b50c63ba51 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2316,6 +2316,9 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
+	if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM)))
+		return -EINVAL;
+
 	start = untagged_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
-- 
2.20.1

[PATCH 13/16] mm: validate get_user_pages_fast flags

[Christoph Hellwig]

We can only deal with FOLL_WRITE and/or FOLL_LONGTERM in
get_user_pages_fast, so reject all other flags.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index c8da7764de9c..53b50c63ba51 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2316,6 +2316,9 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
+	if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM)))
+		return -EINVAL;
+
 	start = untagged_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
-- 
2.20.1

[PATCH 13/16] mm: validate get_user_pages_fast flags

[Christoph Hellwig]

We can only deal with FOLL_WRITE and/or FOLL_LONGTERM in
get_user_pages_fast, so reject all other flags.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index c8da7764de9c..53b50c63ba51 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2316,6 +2316,9 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	unsigned long addr, len, end;
 	int nr = 0, ret = 0;
 
+	if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM)))
+		return -EINVAL;
+
 	start = untagged_addr(start) & PAGE_MASK;
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
-- 
2.20.1

[PATCH 14/16] mm: move the powerpc hugepd code to mm/gup.c

[Christoph Hellwig]

While only powerpc supports the hugepd case, the code is pretty
generic and I'd like to keep all GUP internals in one place.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/Kconfig          |  1 +
 arch/powerpc/mm/hugetlbpage.c | 72 ------------------------------
 include/linux/hugetlb.h       | 18 --------
 mm/Kconfig                    | 10 +++++
 mm/gup.c                      | 82 +++++++++++++++++++++++++++++++++++
 5 files changed, 93 insertions(+), 90 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 992a04796e56..4f1b00979cde 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -125,6 +125,7 @@ config PPC
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_KCOV
+	select ARCH_HAS_HUGEPD			if HUGETLB_PAGE
 	select ARCH_HAS_MMIOWB			if PPC64
 	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_HAS_PMEM_API                if PPC64
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index b5d92dc32844..51716c11d0fb 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -511,13 +511,6 @@ struct page *follow_huge_pd(struct vm_area_struct *vma,
 	return page;
 }
 
-static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
-				      unsigned long sz)
-{
-	unsigned long __boundary = (addr + sz) & ~(sz-1);
-	return (__boundary - 1 < end - 1) ? __boundary : end;
-}
-
 #ifdef CONFIG_PPC_MM_SLICES
 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 					unsigned long len, unsigned long pgoff,
@@ -665,68 +658,3 @@ void flush_dcache_icache_hugepage(struct page *page)
 		}
 	}
 }
-
-static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
-		       unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long pte_end;
-	struct page *head, *page;
-	pte_t pte;
-	int refs;
-
-	pte_end = (addr + sz) & ~(sz-1);
-	if (pte_end < end)
-		end = pte_end;
-
-	pte = READ_ONCE(*ptep);
-
-	if (!pte_access_permitted(pte, write))
-		return 0;
-
-	/* hugepages are never "special" */
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-
-	page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-		/* Could be optimized better */
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned int pdshift,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	pte_t *ptep;
-	unsigned long sz = 1UL << hugepd_shift(hugepd);
-	unsigned long next;
-
-	ptep = hugepte_offset(hugepd, addr, pdshift);
-	do {
-		next = hugepte_addr_end(addr, end, sz);
-		if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
-			return 0;
-	} while (ptep++, addr = next, addr != end);
-
-	return 1;
-}
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index edf476c8cfb9..0f91761e2c53 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -16,29 +16,11 @@ struct user_struct;
 struct mmu_gather;
 
 #ifndef is_hugepd
-/*
- * Some architectures requires a hugepage directory format that is
- * required to support multiple hugepage sizes. For example
- * a4fe3ce76 "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
- * introduced the same on powerpc. This allows for a more flexible hugepage
- * pagetable layout.
- */
 typedef struct { unsigned long pd; } hugepd_t;
 #define is_hugepd(hugepd) (0)
 #define __hugepd(x) ((hugepd_t) { (x) })
-static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-			      unsigned pdshift, unsigned long end,
-			      int write, struct page **pages, int *nr)
-{
-	return 0;
-}
-#else
-extern int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-		       unsigned pdshift, unsigned long end,
-		       int write, struct page **pages, int *nr);
 #endif
 
-
 #ifdef CONFIG_HUGETLB_PAGE
 
 #include <linux/mempolicy.h>
diff --git a/mm/Kconfig b/mm/Kconfig
index 5c41409557da..44be3f01a2b2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -769,4 +769,14 @@ config GUP_GET_PTE_LOW_HIGH
 config ARCH_HAS_PTE_SPECIAL
 	bool
 
+#
+# Some architectures require a special hugepage directory format that is
+# required to support multiple hugepage sizes. For example a4fe3ce76
+# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
+# introduced it on powerpc.  This allows for a more flexible hugepage
+# pagetable layouts.
+#
+config ARCH_HAS_HUGEPD
+	bool
+
 endmenu
diff --git a/mm/gup.c b/mm/gup.c
index 53b50c63ba51..e03c7e6b1422 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1966,6 +1966,88 @@ static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
 }
 #endif
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
+static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
+				      unsigned long sz)
+{
+	unsigned long __boundary = (addr + sz) & ~(sz-1);
+	return (__boundary - 1 < end - 1) ? __boundary : end;
+}
+
+static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
+		       unsigned long end, int write, struct page **pages, int *nr)
+{
+	unsigned long pte_end;
+	struct page *head, *page;
+	pte_t pte;
+	int refs;
+
+	pte_end = (addr + sz) & ~(sz-1);
+	if (pte_end < end)
+		end = pte_end;
+
+	pte = READ_ONCE(*ptep);
+
+	if (!pte_access_permitted(pte, write))
+		return 0;
+
+	/* hugepages are never "special" */
+	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+
+	refs = 0;
+	head = pte_page(pte);
+
+	page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
+	do {
+		VM_BUG_ON(compound_head(page) != head);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
+		/* Could be optimized better */
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+
+	return 1;
+}
+
+static int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+		unsigned int pdshift, unsigned long end, int write,
+		struct page **pages, int *nr)
+{
+	pte_t *ptep;
+	unsigned long sz = 1UL << hugepd_shift(hugepd);
+	unsigned long next;
+
+	ptep = hugepte_offset(hugepd, addr, pdshift);
+	do {
+		next = hugepte_addr_end(addr, end, sz);
+		if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
+			return 0;
+	} while (ptep++, addr = next, addr != end);
+
+	return 1;
+}
+#else
+static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+		unsigned pdshift, unsigned long end, int write,
+		struct page **pages, int *nr)
+{
+	return 0;
+}
+#endif /* CONFIG_ARCH_HAS_HUGEPD */
+
 static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		unsigned long end, unsigned int flags, struct page **pages, int *nr)
 {
-- 
2.20.1

[PATCH 14/16] mm: move the powerpc hugepd code to mm/gup.c

[Christoph Hellwig]

While only powerpc supports the hugepd case, the code is pretty
generic and I'd like to keep all GUP internals in one place.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/Kconfig          |  1 +
 arch/powerpc/mm/hugetlbpage.c | 72 ------------------------------
 include/linux/hugetlb.h       | 18 --------
 mm/Kconfig                    | 10 +++++
 mm/gup.c                      | 82 +++++++++++++++++++++++++++++++++++
 5 files changed, 93 insertions(+), 90 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 992a04796e56..4f1b00979cde 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -125,6 +125,7 @@ config PPC
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_KCOV
+	select ARCH_HAS_HUGEPD			if HUGETLB_PAGE
 	select ARCH_HAS_MMIOWB			if PPC64
 	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_HAS_PMEM_API                if PPC64
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index b5d92dc32844..51716c11d0fb 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -511,13 +511,6 @@ struct page *follow_huge_pd(struct vm_area_struct *vma,
 	return page;
 }
 
-static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
-				      unsigned long sz)
-{
-	unsigned long __boundary = (addr + sz) & ~(sz-1);
-	return (__boundary - 1 < end - 1) ? __boundary : end;
-}
-
 #ifdef CONFIG_PPC_MM_SLICES
 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 					unsigned long len, unsigned long pgoff,
@@ -665,68 +658,3 @@ void flush_dcache_icache_hugepage(struct page *page)
 		}
 	}
 }
-
-static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
-		       unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long pte_end;
-	struct page *head, *page;
-	pte_t pte;
-	int refs;
-
-	pte_end = (addr + sz) & ~(sz-1);
-	if (pte_end < end)
-		end = pte_end;
-
-	pte = READ_ONCE(*ptep);
-
-	if (!pte_access_permitted(pte, write))
-		return 0;
-
-	/* hugepages are never "special" */
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-
-	page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-		/* Could be optimized better */
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned int pdshift,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	pte_t *ptep;
-	unsigned long sz = 1UL << hugepd_shift(hugepd);
-	unsigned long next;
-
-	ptep = hugepte_offset(hugepd, addr, pdshift);
-	do {
-		next = hugepte_addr_end(addr, end, sz);
-		if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
-			return 0;
-	} while (ptep++, addr = next, addr != end);
-
-	return 1;
-}
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index edf476c8cfb9..0f91761e2c53 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -16,29 +16,11 @@ struct user_struct;
 struct mmu_gather;
 
 #ifndef is_hugepd
-/*
- * Some architectures requires a hugepage directory format that is
- * required to support multiple hugepage sizes. For example
- * a4fe3ce76 "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
- * introduced the same on powerpc. This allows for a more flexible hugepage
- * pagetable layout.
- */
 typedef struct { unsigned long pd; } hugepd_t;
 #define is_hugepd(hugepd) (0)
 #define __hugepd(x) ((hugepd_t) { (x) })
-static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-			      unsigned pdshift, unsigned long end,
-			      int write, struct page **pages, int *nr)
-{
-	return 0;
-}
-#else
-extern int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-		       unsigned pdshift, unsigned long end,
-		       int write, struct page **pages, int *nr);
 #endif
 
-
 #ifdef CONFIG_HUGETLB_PAGE
 
 #include <linux/mempolicy.h>
diff --git a/mm/Kconfig b/mm/Kconfig
index 5c41409557da..44be3f01a2b2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -769,4 +769,14 @@ config GUP_GET_PTE_LOW_HIGH
 config ARCH_HAS_PTE_SPECIAL
 	bool
 
+#
+# Some architectures require a special hugepage directory format that is
+# required to support multiple hugepage sizes. For example a4fe3ce76
+# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
+# introduced it on powerpc.  This allows for a more flexible hugepage
+# pagetable layouts.
+#
+config ARCH_HAS_HUGEPD
+	bool
+
 endmenu
diff --git a/mm/gup.c b/mm/gup.c
index 53b50c63ba51..e03c7e6b1422 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1966,6 +1966,88 @@ static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
 }
 #endif
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
+static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
+				      unsigned long sz)
+{
+	unsigned long __boundary = (addr + sz) & ~(sz-1);
+	return (__boundary - 1 < end - 1) ? __boundary : end;
+}
+
+static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
+		       unsigned long end, int write, struct page **pages, int *nr)
+{
+	unsigned long pte_end;
+	struct page *head, *page;
+	pte_t pte;
+	int refs;
+
+	pte_end = (addr + sz) & ~(sz-1);
+	if (pte_end < end)
+		end = pte_end;
+
+	pte = READ_ONCE(*ptep);
+
+	if (!pte_access_permitted(pte, write))
+		return 0;
+
+	/* hugepages are never "special" */
+	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+
+	refs = 0;
+	head = pte_page(pte);
+
+	page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
+	do {
+		VM_BUG_ON(compound_head(page) != head);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
+		/* Could be optimized better */
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+
+	return 1;
+}
+
+static int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+		unsigned int pdshift, unsigned long end, int write,
+		struct page **pages, int *nr)
+{
+	pte_t *ptep;
+	unsigned long sz = 1UL << hugepd_shift(hugepd);
+	unsigned long next;
+
+	ptep = hugepte_offset(hugepd, addr, pdshift);
+	do {
+		next = hugepte_addr_end(addr, end, sz);
+		if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
+			return 0;
+	} while (ptep++, addr = next, addr != end);
+
+	return 1;
+}
+#else
+static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+		unsigned pdshift, unsigned long end, int write,
+		struct page **pages, int *nr)
+{
+	return 0;
+}
+#endif /* CONFIG_ARCH_HAS_HUGEPD */
+
 static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		unsigned long end, unsigned int flags, struct page **pages, int *nr)
 {
-- 
2.20.1

[PATCH 14/16] mm: move the powerpc hugepd code to mm/gup.c

[Christoph Hellwig]

While only powerpc supports the hugepd case, the code is pretty
generic and I'd like to keep all GUP internals in one place.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/Kconfig          |  1 +
 arch/powerpc/mm/hugetlbpage.c | 72 ------------------------------
 include/linux/hugetlb.h       | 18 --------
 mm/Kconfig                    | 10 +++++
 mm/gup.c                      | 82 +++++++++++++++++++++++++++++++++++
 5 files changed, 93 insertions(+), 90 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 992a04796e56..4f1b00979cde 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -125,6 +125,7 @@ config PPC
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_KCOV
+	select ARCH_HAS_HUGEPD			if HUGETLB_PAGE
 	select ARCH_HAS_MMIOWB			if PPC64
 	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_HAS_PMEM_API                if PPC64
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index b5d92dc32844..51716c11d0fb 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -511,13 +511,6 @@ struct page *follow_huge_pd(struct vm_area_struct *vma,
 	return page;
 }
 
-static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
-				      unsigned long sz)
-{
-	unsigned long __boundary = (addr + sz) & ~(sz-1);
-	return (__boundary - 1 < end - 1) ? __boundary : end;
-}
-
 #ifdef CONFIG_PPC_MM_SLICES
 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 					unsigned long len, unsigned long pgoff,
@@ -665,68 +658,3 @@ void flush_dcache_icache_hugepage(struct page *page)
 		}
 	}
 }
-
-static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
-		       unsigned long end, int write, struct page **pages, int *nr)
-{
-	unsigned long pte_end;
-	struct page *head, *page;
-	pte_t pte;
-	int refs;
-
-	pte_end = (addr + sz) & ~(sz-1);
-	if (pte_end < end)
-		end = pte_end;
-
-	pte = READ_ONCE(*ptep);
-
-	if (!pte_access_permitted(pte, write))
-		return 0;
-
-	/* hugepages are never "special" */
-	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-	refs = 0;
-	head = pte_page(pte);
-
-	page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
-	do {
-		VM_BUG_ON(compound_head(page) != head);
-		pages[*nr] = page;
-		(*nr)++;
-		page++;
-		refs++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	if (!page_cache_add_speculative(head, refs)) {
-		*nr -= refs;
-		return 0;
-	}
-
-	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
-		/* Could be optimized better */
-		*nr -= refs;
-		while (refs--)
-			put_page(head);
-		return 0;
-	}
-
-	return 1;
-}
-
-int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned int pdshift,
-		unsigned long end, int write, struct page **pages, int *nr)
-{
-	pte_t *ptep;
-	unsigned long sz = 1UL << hugepd_shift(hugepd);
-	unsigned long next;
-
-	ptep = hugepte_offset(hugepd, addr, pdshift);
-	do {
-		next = hugepte_addr_end(addr, end, sz);
-		if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
-			return 0;
-	} while (ptep++, addr = next, addr != end);
-
-	return 1;
-}
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index edf476c8cfb9..0f91761e2c53 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -16,29 +16,11 @@ struct user_struct;
 struct mmu_gather;
 
 #ifndef is_hugepd
-/*
- * Some architectures requires a hugepage directory format that is
- * required to support multiple hugepage sizes. For example
- * a4fe3ce76 "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
- * introduced the same on powerpc. This allows for a more flexible hugepage
- * pagetable layout.
- */
 typedef struct { unsigned long pd; } hugepd_t;
 #define is_hugepd(hugepd) (0)
 #define __hugepd(x) ((hugepd_t) { (x) })
-static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-			      unsigned pdshift, unsigned long end,
-			      int write, struct page **pages, int *nr)
-{
-	return 0;
-}
-#else
-extern int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-		       unsigned pdshift, unsigned long end,
-		       int write, struct page **pages, int *nr);
 #endif
 
-
 #ifdef CONFIG_HUGETLB_PAGE
 
 #include <linux/mempolicy.h>
diff --git a/mm/Kconfig b/mm/Kconfig
index 5c41409557da..44be3f01a2b2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -769,4 +769,14 @@ config GUP_GET_PTE_LOW_HIGH
 config ARCH_HAS_PTE_SPECIAL
 	bool
 
+#
+# Some architectures require a special hugepage directory format that is
+# required to support multiple hugepage sizes. For example a4fe3ce76
+# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
+# introduced it on powerpc.  This allows for a more flexible hugepage
+# pagetable layouts.
+#
+config ARCH_HAS_HUGEPD
+	bool
+
 endmenu
diff --git a/mm/gup.c b/mm/gup.c
index 53b50c63ba51..e03c7e6b1422 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1966,6 +1966,88 @@ static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
 }
 #endif
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
+static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
+				      unsigned long sz)
+{
+	unsigned long __boundary = (addr + sz) & ~(sz-1);
+	return (__boundary - 1 < end - 1) ? __boundary : end;
+}
+
+static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
+		       unsigned long end, int write, struct page **pages, int *nr)
+{
+	unsigned long pte_end;
+	struct page *head, *page;
+	pte_t pte;
+	int refs;
+
+	pte_end = (addr + sz) & ~(sz-1);
+	if (pte_end < end)
+		end = pte_end;
+
+	pte = READ_ONCE(*ptep);
+
+	if (!pte_access_permitted(pte, write))
+		return 0;
+
+	/* hugepages are never "special" */
+	VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+
+	refs = 0;
+	head = pte_page(pte);
+
+	page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
+	do {
+		VM_BUG_ON(compound_head(page) != head);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
+		/* Could be optimized better */
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+
+	return 1;
+}
+
+static int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+		unsigned int pdshift, unsigned long end, int write,
+		struct page **pages, int *nr)
+{
+	pte_t *ptep;
+	unsigned long sz = 1UL << hugepd_shift(hugepd);
+	unsigned long next;
+
+	ptep = hugepte_offset(hugepd, addr, pdshift);
+	do {
+		next = hugepte_addr_end(addr, end, sz);
+		if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
+			return 0;
+	} while (ptep++, addr = next, addr != end);
+
+	return 1;
+}
+#else
+static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+		unsigned pdshift, unsigned long end, int write,
+		struct page **pages, int *nr)
+{
+	return 0;
+}
+#endif /* CONFIG_ARCH_HAS_HUGEPD */
+
 static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		unsigned long end, unsigned int flags, struct page **pages, int *nr)
 {
-- 
2.20.1

[PATCH 15/16] mm: switch gup_hugepte to use try_get_compound_head

[Christoph Hellwig]

This applies the overflow fixes from 8fde12ca79aff
("mm: prevent get_user_pages() from overflowing page refcount")
to the powerpc hugepd code and brings it back in sync with the
other GUP cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index e03c7e6b1422..6090044227f1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2006,7 +2006,8 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
-	if (!page_cache_add_speculative(head, refs)) {
+	head = try_get_compound_head(head, refs);
+	if (!head) {
 		*nr -= refs;
 		return 0;
 	}
-- 
2.20.1

[PATCH 15/16] mm: switch gup_hugepte to use try_get_compound_head

[Christoph Hellwig]

This applies the overflow fixes from 8fde12ca79aff
("mm: prevent get_user_pages() from overflowing page refcount")
to the powerpc hugepd code and brings it back in sync with the
other GUP cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index e03c7e6b1422..6090044227f1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2006,7 +2006,8 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
-	if (!page_cache_add_speculative(head, refs)) {
+	head = try_get_compound_head(head, refs);
+	if (!head) {
 		*nr -= refs;
 		return 0;
 	}
-- 
2.20.1

[PATCH 15/16] mm: switch gup_hugepte to use try_get_compound_head

[Christoph Hellwig]

This applies the overflow fixes from 8fde12ca79aff
("mm: prevent get_user_pages() from overflowing page refcount")
to the powerpc hugepd code and brings it back in sync with the
other GUP cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index e03c7e6b1422..6090044227f1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2006,7 +2006,8 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
-	if (!page_cache_add_speculative(head, refs)) {
+	head = try_get_compound_head(head, refs);
+	if (!head) {
 		*nr -= refs;
 		return 0;
 	}
-- 
2.20.1

[PATCH 16/16] mm: mark the page referenced in gup_hugepte

[Christoph Hellwig]

All other get_user_page_fast cases mark the page referenced, so do
this here as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/gup.c b/mm/gup.c
index 6090044227f1..d1fc008de292 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2020,6 +2020,7 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 		return 0;
 	}
 
+	SetPageReferenced(head);
 	return 1;
 }
 
-- 
2.20.1

[PATCH 16/16] mm: mark the page referenced in gup_hugepte

[Christoph Hellwig]

All other get_user_page_fast cases mark the page referenced, so do
this here as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/gup.c b/mm/gup.c
index 6090044227f1..d1fc008de292 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2020,6 +2020,7 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 		return 0;
 	}
 
+	SetPageReferenced(head);
 	return 1;
 }
 
-- 
2.20.1

[PATCH 16/16] mm: mark the page referenced in gup_hugepte

[Christoph Hellwig]

All other get_user_page_fast cases mark the page referenced, so do
this here as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/gup.c b/mm/gup.c
index 6090044227f1..d1fc008de292 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2020,6 +2020,7 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 		return 0;
 	}
 
+	SetPageReferenced(head);
 	return 1;
 }
 
-- 
2.20.1

Re: RFC: switch the remaining architectures to use generic GUP v2

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Sat,  1 Jun 2019 09:49:43 +0200

> below is a series to switch mips, sh and sparc64 to use the generic
> GUP code so that we only have one codebase to touch for further
> improvements to this code.  I don't have hardware for any of these
> architectures, and generally no clue about their page table
> management, so handle with care.
> 
> Changes since v1:
>  - fix various issues found by the build bot
>  - cherry pick and use the untagged_addr helper form Andrey
>  - add various refactoring patches to share more code over architectures
>  - move the powerpc hugepd code to mm/gup.c and sync it with the generic
>    hup semantics

I will today look seriously at the sparc64 stuff wrt. tagged pointers.

Re: RFC: switch the remaining architectures to use generic GUP v2

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Sat,  1 Jun 2019 09:49:43 +0200

> below is a series to switch mips, sh and sparc64 to use the generic
> GUP code so that we only have one codebase to touch for further
> improvements to this code.  I don't have hardware for any of these
> architectures, and generally no clue about their page table
> management, so handle with care.
> 
> Changes since v1:
>  - fix various issues found by the build bot
>  - cherry pick and use the untagged_addr helper form Andrey
>  - add various refactoring patches to share more code over architectures
>  - move the powerpc hugepd code to mm/gup.c and sync it with the generic
>    hup semantics

I will today look seriously at the sparc64 stuff wrt. tagged pointers.

Re: RFC: switch the remaining architectures to use generic GUP v2

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Sat,  1 Jun 2019 09:49:43 +0200

> below is a series to switch mips, sh and sparc64 to use the generic
> GUP code so that we only have one codebase to touch for further
> improvements to this code.  I don't have hardware for any of these
> architectures, and generally no clue about their page table
> management, so handle with care.
> 
> Changes since v1:
>  - fix various issues found by the build bot
>  - cherry pick and use the untagged_addr helper form Andrey
>  - add various refactoring patches to share more code over architectures
>  - move the powerpc hugepd code to mm/gup.c and sync it with the generic
>    hup semantics

I will today look seriously at the sparc64 stuff wrt. tagged pointers.