[PATCH V2 RESEND] mm: Define default value for FIRST_USER_ADDRESS

* [PATCH V2 RESEND] mm: Define default value for FIRST_USER_ADDRESS
@ 2021-05-10  3:02 Anshuman Khandual
  2021-05-23 22:32 ` Palmer Dabbelt
  0 siblings, 1 reply; 2+ messages in thread
From: Anshuman Khandual @ 2021-05-10  3:02 UTC (permalink / raw)
  To: linux-mm, akpm
  Cc: Anshuman Khandual, Richard Henderson, Vineet Gupta,
	Catalin Marinas, Will Deacon, Guo Ren, Brian Cain,
	Geert Uytterhoeven, Michal Simek, Thomas Bogendoerfer,
	Ley Foon Tan, Jonas Bonn, Stefan Kristiansson, Stafford Horne,
	James E.J. Bottomley, Michael Ellerman, Christophe Leroy,
	Paul Walmsley, Palmer Dabbelt, Heiko Carstens, Yoshinori Sato,
	David S. Miller, Jeff Dike, Thomas Gleixner, Chris Zankel,
	linux-arch, linux-kernel

Currently most platforms define FIRST_USER_ADDRESS as 0UL duplication the
same code all over. Instead just define a generic default value (i.e 0UL)
for FIRST_USER_ADDRESS and let the platforms override when required. This
makes it much cleaner with reduced code.

The default FIRST_USER_ADDRESS here would be skipped in <linux/pgtable.h>
when the given platform overrides its value via <asm/pgtable.h>.

Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> #m68k
Acked-by: Guo Ren <guoren@kernel.org>               #csky
Acked-by: Stafford Horne <shorne@gmail.com>         #openrisc
Acked-by: Catalin Marinas <catalin.marinas@arm.com> #arm64
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
This applies on v5.13-rc1 and has been boot tested on arm64 platform.
But has been cross compiled on multiple other platforms.

Changes in V2:

- Dropped ARCH_HAS_FIRST_USER_ADDRESS construct

Changes in V1:

https://patchwork.kernel.org/project/linux-mm/patch/1618368899-20311-1-git-send-email-anshuman.khandual@arm.com/

 arch/alpha/include/asm/pgtable.h             | 1 -
 arch/arc/include/asm/pgtable.h               | 6 ------
 arch/arm64/include/asm/pgtable.h             | 2 --
 arch/csky/include/asm/pgtable.h              | 1 -
 arch/hexagon/include/asm/pgtable.h           | 3 ---
 arch/ia64/include/asm/pgtable.h              | 1 -
 arch/m68k/include/asm/pgtable_mm.h           | 1 -
 arch/microblaze/include/asm/pgtable.h        | 2 --
 arch/mips/include/asm/pgtable-32.h           | 1 -
 arch/mips/include/asm/pgtable-64.h           | 1 -
 arch/nios2/include/asm/pgtable.h             | 2 --
 arch/openrisc/include/asm/pgtable.h          | 1 -
 arch/parisc/include/asm/pgtable.h            | 2 --
 arch/powerpc/include/asm/book3s/pgtable.h    | 1 -
 arch/powerpc/include/asm/nohash/32/pgtable.h | 1 -
 arch/powerpc/include/asm/nohash/64/pgtable.h | 2 --
 arch/riscv/include/asm/pgtable.h             | 2 --
 arch/s390/include/asm/pgtable.h              | 2 --
 arch/sh/include/asm/pgtable.h                | 2 --
 arch/sparc/include/asm/pgtable_32.h          | 1 -
 arch/sparc/include/asm/pgtable_64.h          | 3 ---
 arch/um/include/asm/pgtable-2level.h         | 1 -
 arch/um/include/asm/pgtable-3level.h         | 1 -
 arch/x86/include/asm/pgtable_types.h         | 2 --
 arch/xtensa/include/asm/pgtable.h            | 1 -
 include/linux/pgtable.h                      | 9 +++++++++
 26 files changed, 9 insertions(+), 43 deletions(-)

diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
index 8d856c62e22a..1a2fb0dc905b 100644
--- a/arch/alpha/include/asm/pgtable.h
+++ b/arch/alpha/include/asm/pgtable.h
@@ -46,7 +46,6 @@ struct vm_area_struct;
 #define PTRS_PER_PMD	(1UL << (PAGE_SHIFT-3))
 #define PTRS_PER_PGD	(1UL << (PAGE_SHIFT-3))
 #define USER_PTRS_PER_PGD	(TASK_SIZE / PGDIR_SIZE)
-#define FIRST_USER_ADDRESS	0UL
 
 /* Number of pointers that fit on a page:  this will go away. */
 #define PTRS_PER_PAGE	(1UL << (PAGE_SHIFT-3))
diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h
index 163641726a2b..a9fabfb70664 100644
--- a/arch/arc/include/asm/pgtable.h
+++ b/arch/arc/include/asm/pgtable.h
@@ -228,12 +228,6 @@
  */
 #define	USER_PTRS_PER_PGD	(TASK_SIZE / PGDIR_SIZE)
 
-/*
- * No special requirements for lowest virtual address we permit any user space
- * mapping to be mapped at.
- */
-#define FIRST_USER_ADDRESS      0UL
-
 
 /****************************************************************
  * Bucket load of VM Helpers
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 0b10204e72fc..25f5c04b43ce 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -26,8 +26,6 @@
 
 #define vmemmap			((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))
 
-#define FIRST_USER_ADDRESS	0UL
-
 #ifndef __ASSEMBLY__
 
 #include <asm/cmpxchg.h>
diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgtable.h
index 0d60367b6bfa..151607ed5158 100644
--- a/arch/csky/include/asm/pgtable.h
+++ b/arch/csky/include/asm/pgtable.h
@@ -14,7 +14,6 @@
 #define PGDIR_MASK		(~(PGDIR_SIZE-1))
 
 #define USER_PTRS_PER_PGD	(PAGE_OFFSET/PGDIR_SIZE)
-#define FIRST_USER_ADDRESS	0UL
 
 /*
  * C-SKY is two-level paging structure:
diff --git a/arch/hexagon/include/asm/pgtable.h b/arch/hexagon/include/asm/pgtable.h
index dbb22b80b8c4..e4979508cddf 100644
--- a/arch/hexagon/include/asm/pgtable.h
+++ b/arch/hexagon/include/asm/pgtable.h
@@ -155,9 +155,6 @@ extern unsigned long _dflt_cache_att;
 
 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];  /* located in head.S */
 
-/* Seems to be zero even in architectures where the zero page is firewalled? */
-#define FIRST_USER_ADDRESS 0UL
-
 /*  HUGETLB not working currently  */
 #ifdef CONFIG_HUGETLB_PAGE
 #define pte_mkhuge(pte) __pte((pte_val(pte) & ~0x3) | HVM_HUGEPAGE_SIZE)
diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index d765fd948fae..3f5dbbd8b9d8 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -128,7 +128,6 @@
 #define PTRS_PER_PGD_SHIFT	PTRS_PER_PTD_SHIFT
 #define PTRS_PER_PGD		(1UL << PTRS_PER_PGD_SHIFT)
 #define USER_PTRS_PER_PGD	(5*PTRS_PER_PGD/8)	/* regions 0-4 are user regions */
-#define FIRST_USER_ADDRESS	0UL
 
 /*
  * All the normal masks have the "page accessed" bits on, as any time
diff --git a/arch/m68k/include/asm/pgtable_mm.h b/arch/m68k/include/asm/pgtable_mm.h
index aca22c2c1ee2..143ba7de9bda 100644
--- a/arch/m68k/include/asm/pgtable_mm.h
+++ b/arch/m68k/include/asm/pgtable_mm.h
@@ -72,7 +72,6 @@
 #define PTRS_PER_PGD	128
 #endif
 #define USER_PTRS_PER_PGD	(TASK_SIZE/PGDIR_SIZE)
-#define FIRST_USER_ADDRESS	0UL
 
 /* Virtual address region for use by kernel_map() */
 #ifdef CONFIG_SUN3
diff --git a/arch/microblaze/include/asm/pgtable.h b/arch/microblaze/include/asm/pgtable.h
index 9ae8d2c17dd5..71cd547655d9 100644
--- a/arch/microblaze/include/asm/pgtable.h
+++ b/arch/microblaze/include/asm/pgtable.h
@@ -25,8 +25,6 @@ extern int mem_init_done;
 #include <asm/mmu.h>
 #include <asm/page.h>
 
-#define FIRST_USER_ADDRESS	0UL
-
 extern unsigned long va_to_phys(unsigned long address);
 extern pte_t *va_to_pte(unsigned long address);
 
diff --git a/arch/mips/include/asm/pgtable-32.h b/arch/mips/include/asm/pgtable-32.h
index 6c0532d7b211..95df9c293d8d 100644
--- a/arch/mips/include/asm/pgtable-32.h
+++ b/arch/mips/include/asm/pgtable-32.h
@@ -93,7 +93,6 @@ extern int add_temporary_entry(unsigned long entrylo0, unsigned long entrylo1,
 #endif
 
 #define USER_PTRS_PER_PGD	(0x80000000UL/PGDIR_SIZE)
-#define FIRST_USER_ADDRESS	0UL
 
 #define VMALLOC_START	  MAP_BASE
 
diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h
index 1e7d6ce9d8d6..046465906c82 100644
--- a/arch/mips/include/asm/pgtable-64.h
+++ b/arch/mips/include/asm/pgtable-64.h
@@ -137,7 +137,6 @@
 #define PTRS_PER_PTE	((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))
 
 #define USER_PTRS_PER_PGD       ((TASK_SIZE64 / PGDIR_SIZE)?(TASK_SIZE64 / PGDIR_SIZE):1)
-#define FIRST_USER_ADDRESS	0UL
 
 /*
  * TLB refill handlers also map the vmalloc area into xuseg.  Avoid
diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/pgtable.h
index 2600d76c310c..4a995fa628ee 100644
--- a/arch/nios2/include/asm/pgtable.h
+++ b/arch/nios2/include/asm/pgtable.h
@@ -24,8 +24,6 @@
 #include <asm/pgtable-bits.h>
 #include <asm-generic/pgtable-nopmd.h>
 
-#define FIRST_USER_ADDRESS	0UL
-
 #define VMALLOC_START		CONFIG_NIOS2_KERNEL_MMU_REGION_BASE
 #define VMALLOC_END		(CONFIG_NIOS2_KERNEL_REGION_BASE - 1)
 
diff --git a/arch/openrisc/include/asm/pgtable.h b/arch/openrisc/include/asm/pgtable.h
index 9425bedab4fc..4ac591c9ca33 100644
--- a/arch/openrisc/include/asm/pgtable.h
+++ b/arch/openrisc/include/asm/pgtable.h
@@ -73,7 +73,6 @@ extern void paging_init(void);
  */
 
 #define USER_PTRS_PER_PGD       (TASK_SIZE/PGDIR_SIZE)
-#define FIRST_USER_ADDRESS      0UL
 
 /*
  * Kernels own virtual memory area.
diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h
index 39017210dbf0..7f33c29764cc 100644
--- a/arch/parisc/include/asm/pgtable.h
+++ b/arch/parisc/include/asm/pgtable.h
@@ -171,8 +171,6 @@ static inline void purge_tlb_entries(struct mm_struct *mm, unsigned long addr)
  * pgd entries used up by user/kernel:
  */
 
-#define FIRST_USER_ADDRESS	0UL
-
 /* NB: The tlb miss handlers make certain assumptions about the order */
 /*     of the following bits, so be careful (One example, bits 25-31  */
 /*     are moved together in one instruction).                        */
diff --git a/arch/powerpc/include/asm/book3s/pgtable.h b/arch/powerpc/include/asm/book3s/pgtable.h
index 0e1263455d73..ad130e15a126 100644
--- a/arch/powerpc/include/asm/book3s/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/pgtable.h
@@ -8,7 +8,6 @@
 #include <asm/book3s/32/pgtable.h>
 #endif
 
-#define FIRST_USER_ADDRESS	0UL
 #ifndef __ASSEMBLY__
 /* Insert a PTE, top-level function is out of line. It uses an inline
  * low level function in the respective pgtable-* files
diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
index 96522f7f0618..f06ae00f2a65 100644
--- a/arch/powerpc/include/asm/nohash/32/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
@@ -54,7 +54,6 @@ extern int icache_44x_need_flush;
 #define PGD_MASKED_BITS		0
 
 #define USER_PTRS_PER_PGD	(TASK_SIZE / PGDIR_SIZE)
-#define FIRST_USER_ADDRESS	0UL
 
 #define pte_ERROR(e) \
 	pr_err("%s:%d: bad pte %llx.\n", __FILE__, __LINE__, \
diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
index 57cd3892bfe0..53fbfdfac93d 100644
--- a/arch/powerpc/include/asm/nohash/64/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
@@ -12,8 +12,6 @@
 #include <asm/barrier.h>
 #include <asm/asm-const.h>
 
-#define FIRST_USER_ADDRESS	0UL
-
 /*
  * Size of EA range mapped by our pagetables.
  */
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 9469f464e71a..286870765b49 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -537,8 +537,6 @@ void setup_bootmem(void);
 void paging_init(void);
 void misc_mem_init(void);
 
-#define FIRST_USER_ADDRESS  0
-
 /*
  * ZERO_PAGE is a global shared page that is always zero,
  * used for zero-mapped memory areas, etc.
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 29c7ecd5ad1d..4ee49bb98f34 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -65,8 +65,6 @@ extern unsigned long zero_page_mask;
 
 /* TODO: s390 cannot support io_remap_pfn_range... */
 
-#define FIRST_USER_ADDRESS  0UL
-
 #define pte_ERROR(e) \
 	printk("%s:%d: bad pte %p.\n", __FILE__, __LINE__, (void *) pte_val(e))
 #define pmd_ERROR(e) \
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 27751e9470df..d7ddb1ec86a0 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -59,8 +59,6 @@ static inline unsigned long long neff_sign_extend(unsigned long val)
 /* Entries per level */
 #define PTRS_PER_PTE	(PAGE_SIZE / (1 << PTE_MAGNITUDE))
 
-#define FIRST_USER_ADDRESS	0UL
-
 #define PHYS_ADDR_MASK29		0x1fffffff
 #define PHYS_ADDR_MASK32		0xffffffff
 
diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h
index a5cf79c149fe..0888bda245f5 100644
--- a/arch/sparc/include/asm/pgtable_32.h
+++ b/arch/sparc/include/asm/pgtable_32.h
@@ -48,7 +48,6 @@ unsigned long __init bootmem_init(unsigned long *pages_avail);
 #define PTRS_PER_PMD    	64
 #define PTRS_PER_PGD    	256
 #define USER_PTRS_PER_PGD	PAGE_OFFSET / PGDIR_SIZE
-#define FIRST_USER_ADDRESS	0UL
 #define PTE_SIZE		(PTRS_PER_PTE*4)
 
 #define PAGE_NONE	SRMMU_PAGE_NONE
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 550d3904de65..57460b7ada7b 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -95,9 +95,6 @@ bool kern_addr_valid(unsigned long addr);
 #define PTRS_PER_PUD	(1UL << PUD_BITS)
 #define PTRS_PER_PGD	(1UL << PGDIR_BITS)
 
-/* Kernel has a separate 44bit address space. */
-#define FIRST_USER_ADDRESS	0UL
-
 #define pmd_ERROR(e)							\
 	pr_err("%s:%d: bad pmd %p(%016lx) seen at (%pS)\n",		\
 	       __FILE__, __LINE__, &(e), pmd_val(e), __builtin_return_address(0))
diff --git a/arch/um/include/asm/pgtable-2level.h b/arch/um/include/asm/pgtable-2level.h
index 32106d31e4ab..8256ecc5b919 100644
--- a/arch/um/include/asm/pgtable-2level.h
+++ b/arch/um/include/asm/pgtable-2level.h
@@ -23,7 +23,6 @@
 #define PTRS_PER_PTE	1024
 #define USER_PTRS_PER_PGD ((TASK_SIZE + (PGDIR_SIZE - 1)) / PGDIR_SIZE)
 #define PTRS_PER_PGD	1024
-#define FIRST_USER_ADDRESS	0UL
 
 #define pte_ERROR(e) \
         printk("%s:%d: bad pte %p(%08lx).\n", __FILE__, __LINE__, &(e), \
diff --git a/arch/um/include/asm/pgtable-3level.h b/arch/um/include/asm/pgtable-3level.h
index 7e6a4180db9d..9289a86643a9 100644
--- a/arch/um/include/asm/pgtable-3level.h
+++ b/arch/um/include/asm/pgtable-3level.h
@@ -41,7 +41,6 @@
 #endif
 
 #define USER_PTRS_PER_PGD ((TASK_SIZE + (PGDIR_SIZE - 1)) / PGDIR_SIZE)
-#define FIRST_USER_ADDRESS	0UL
 
 #define pte_ERROR(e) \
         printk("%s:%d: bad pte %p(%016lx).\n", __FILE__, __LINE__, &(e), \
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index f24d7ef8fffa..40497a9020c6 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -7,8 +7,6 @@
 
 #include <asm/page_types.h>
 
-#define FIRST_USER_ADDRESS	0UL
-
 #define _PAGE_BIT_PRESENT	0	/* is present */
 #define _PAGE_BIT_RW		1	/* writeable */
 #define _PAGE_BIT_USER		2	/* userspace addressable */
diff --git a/arch/xtensa/include/asm/pgtable.h b/arch/xtensa/include/asm/pgtable.h
index d7fc45c920c2..bd5aeb795567 100644
--- a/arch/xtensa/include/asm/pgtable.h
+++ b/arch/xtensa/include/asm/pgtable.h
@@ -59,7 +59,6 @@
 #define PTRS_PER_PGD		1024
 #define PGD_ORDER		0
 #define USER_PTRS_PER_PGD	(TASK_SIZE/PGDIR_SIZE)
-#define FIRST_USER_ADDRESS	0UL
 #define FIRST_USER_PGD_NR	(FIRST_USER_ADDRESS >> PGDIR_SHIFT)
 
 #ifdef CONFIG_MMU
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 46b13780c2c8..1bed8b82e59d 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -28,6 +28,15 @@
 #define USER_PGTABLES_CEILING	0UL
 #endif
 
+/*
+ * This defines the first usable user address. Platforms
+ * can override its value with custom FIRST_USER_ADDRESS
+ * defined in their respective <asm/pgtable.h>.
+ */
+#ifndef FIRST_USER_ADDRESS
+#define FIRST_USER_ADDRESS	0UL
+#endif
+
 /*
  * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
  *
-- 
2.20.1


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