[PATCH 0/2] arm: add early_ioremap support

[PATCH 0/2] arm: add early_ioremap support

[Leif Lindholm]

early_ioremap()/early_memremap() create temporary virtual mappings
in the fixmap region during boot time. Part of the support now exists
in core code, but depends on the generic fixmap support.

This set converts arm to use the generic fixmap support, and adds the
architecture-specific part of early_ioremap support.

The fixmap/kmap changes in 3.15 complicated things slightly compared
to previous iterations of these patches - this version works around
that by introducing local macros in arm/mm/highmem.c.

Tested on TC2 and software models, with/without LPAE.

Mark Salter (2):
  arm: use generic fixmap.h
  arm: add early_ioremap support

 arch/arm/Kconfig              |   11 ++++++
 arch/arm/include/asm/Kbuild   |    1 +
 arch/arm/include/asm/fixmap.h |   45 +++++++++++++--------
 arch/arm/include/asm/io.h     |    1 +
 arch/arm/kernel/setup.c       |    3 ++
 arch/arm/mm/Makefile          |    1 +
 arch/arm/mm/early_ioremap.c   |   86 +++++++++++++++++++++++++++++++++++++++++
 arch/arm/mm/highmem.c         |   13 ++++---
 arch/arm/mm/init.c            |    2 +-
 arch/arm/mm/mmu.c             |    2 +
 10 files changed, 143 insertions(+), 22 deletions(-)
 create mode 100644 arch/arm/mm/early_ioremap.c

-- 
1.7.10.4

[PATCH 1/2] arm: use generic fixmap.h

[Leif Lindholm]

From: Mark Salter <msalter@redhat.com>

ARM is different from other architectures in that fixmap pages are
indexed with a positive offset from FIXADDR_START. Other architectures
index with a negative offset from FIXADDR_TOP. In order to use the
generic fixmap.h definitions, this patch redefines FIXADDR_TOP to be
inclusive of the useable range. That is, FIXADDR_TOP is the virtual
address of the topmost fixed page. The newly defined FIXADDR_END is
the first virtual address past the fixed mappings.

The patch also introduces local helper macros in highmem.c to reverse
the iteration order of fixmap pages.

Signed-off-by: Mark Salter <msalter@redhat.com>
[Rebased to 3.16-rc4, reverse kmap fixmap traversal]
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
---
 arch/arm/include/asm/fixmap.h |   45 ++++++++++++++++++++++++++---------------
 arch/arm/mm/highmem.c         |   13 +++++++-----
 arch/arm/mm/init.c            |    2 +-
 3 files changed, 38 insertions(+), 22 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 74124b0..8992431 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -1,28 +1,41 @@
 #ifndef _ASM_FIXMAP_H
 #define _ASM_FIXMAP_H
 
+#include <asm/pgtable.h>
+
 #define FIXADDR_START		0xffc00000UL
-#define FIXADDR_TOP		0xffe00000UL
-#define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
+#define FIXADDR_END		0xffe00000UL
+#define FIXADDR_SIZE		(FIXADDR_END - FIXADDR_START)
+#define FIXADDR_TOP		(FIXADDR_END - PAGE_SIZE)
 
 #define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
 
-#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
-#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
+enum fixed_addresses {
+	FIX_KMAP_BEGIN,
+	FIX_KMAP_END = FIX_KMAP_NR_PTES - 1,
+	__end_of_fixed_addresses
+};
+
+/*
+ * Temporary boot-time mappings, used by early_ioremap(),
+ * before ioremap() is functional.
+ *
+ * (P)re-using the last pmd of the FIXADDR region, which is used for
+ * highmem later on, and statically aligned to 1MB.
+ * Growing down from FIXADDR_TOP
+ */
+#define NR_FIX_BTMAPS		32
+#define FIX_BTMAPS_SLOTS	(PTRS_PER_PTE / NR_FIX_BTMAPS)
+#define TOTAL_FIX_BTMAPS	(NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
+#define FIX_BTMAP_END		FIX_KMAP_BEGIN
+#define FIX_BTMAP_BEGIN		(FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1)
 
-extern void __this_fixmap_does_not_exist(void);
+#define FIXMAP_PAGE_NORMAL (L_PTE_MT_WRITEBACK | L_PTE_YOUNG | L_PTE_PRESENT)
+#define FIXMAP_PAGE_IO (L_PTE_MT_DEV_NONSHARED | L_PTE_YOUNG | L_PTE_PRESENT)
 
-static inline unsigned long fix_to_virt(const unsigned int idx)
-{
-	if (idx >= FIX_KMAP_NR_PTES)
-		__this_fixmap_does_not_exist();
-	return __fix_to_virt(idx);
-}
+extern void __early_set_fixmap(enum fixed_addresses idx,
+			       phys_addr_t phys, pgprot_t flags);
 
-static inline unsigned int virt_to_fix(const unsigned long vaddr)
-{
-	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
-	return __virt_to_fix(vaddr);
-}
+#include <asm-generic/fixmap.h>
 
 #endif
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index 45aeaac..3c59cdf 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -20,16 +20,19 @@
 
 pte_t *fixmap_page_table;
 
+#define __kmap_fix_to_virt(x)	(__fix_to_virt(FIX_KMAP_NR_PTES - 1 - (x)))
+#define __kmap_virt_to_fix(x)	(FIX_KMAP_NR_PTES - 1 - __fix_to_virt(x))
+
 static inline void set_fixmap_pte(int idx, pte_t pte)
 {
-	unsigned long vaddr = __fix_to_virt(idx);
+	unsigned long vaddr = __kmap_fix_to_virt(idx);
 	set_pte_ext(fixmap_page_table + idx, pte, 0);
 	local_flush_tlb_kernel_page(vaddr);
 }
 
 static inline pte_t get_fixmap_pte(unsigned long vaddr)
 {
-	unsigned long idx = __virt_to_fix(vaddr);
+	unsigned long idx = __kmap_virt_to_fix(vaddr);
 	return *(fixmap_page_table + idx);
 }
 
@@ -78,7 +81,7 @@ void *kmap_atomic(struct page *page)
 	type = kmap_atomic_idx_push();
 
 	idx = type + KM_TYPE_NR * smp_processor_id();
-	vaddr = __fix_to_virt(idx);
+	vaddr = __kmap_fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
 	/*
 	 * With debugging enabled, kunmap_atomic forces that entry to 0.
@@ -109,7 +112,7 @@ void __kunmap_atomic(void *kvaddr)
 		if (cache_is_vivt())
 			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 #ifdef CONFIG_DEBUG_HIGHMEM
-		BUG_ON(vaddr != __fix_to_virt(idx));
+		BUG_ON(vaddr != __kmap_fix_to_virt(idx));
 		set_fixmap_pte(idx, __pte(0));
 #else
 		(void) idx;  /* to kill a warning */
@@ -132,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR * smp_processor_id();
-	vaddr = __fix_to_virt(idx);
+	vaddr = __kmap_fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
 	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
 #endif
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 659c75d..ad82c05 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -570,7 +570,7 @@ void __init mem_init(void)
 			MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
 			MLK(ITCM_OFFSET, (unsigned long) itcm_end),
 #endif
-			MLK(FIXADDR_START, FIXADDR_TOP),
+			MLK(FIXADDR_START, FIXADDR_END),
 			MLM(VMALLOC_START, VMALLOC_END),
 			MLM(PAGE_OFFSET, (unsigned long)high_memory),
 #ifdef CONFIG_HIGHMEM
-- 
1.7.10.4

[PATCH 2/2] arm: add early_ioremap support

[Leif Lindholm]

From: Mark Salter <msalter@redhat.com>

This patch uses the generic early_ioremap code to implement
early_ioremap for ARM. The ARM-specific bits come mostly from
an earlier patch from Leif Lindholm <leif.lindholm@linaro.org>
here:

  https://lkml.org/lkml/2013/10/3/279

Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
CC: linux-arm-kernel at lists.infradead.org
CC: Russell King <linux@arm.linux.org.uk>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm/Kconfig            |   11 ++++++
 arch/arm/include/asm/Kbuild |    1 +
 arch/arm/include/asm/io.h   |    1 +
 arch/arm/kernel/setup.c     |    3 ++
 arch/arm/mm/Makefile        |    1 +
 arch/arm/mm/early_ioremap.c |   86 +++++++++++++++++++++++++++++++++++++++++++
 arch/arm/mm/mmu.c           |    2 +
 7 files changed, 105 insertions(+)
 create mode 100644 arch/arm/mm/early_ioremap.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 245058b..04b8f8a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1800,6 +1800,17 @@ config UACCESS_WITH_MEMCPY
 	  However, if the CPU data cache is using a write-allocate mode,
 	  this option is unlikely to provide any performance gain.
 
+config EARLY_IOREMAP
+	depends on MMU
+	bool "Provide early_ioremap() support for kernel initialization."
+	select GENERIC_EARLY_IOREMAP
+	help
+	  Provide a mechanism for kernel initialisation code to temporarily
+	  map, in a highmem-agnostic way, memory pages in before ioremap()
+	  and friends are available (before paging_init() has run). It uses
+	  the same virtual memory range as kmap so all early mappings must
+	  be unmapped before paging_init() is called.
+
 config SECCOMP
 	bool
 	prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index f5a3576..0bc5a02 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -4,6 +4,7 @@ generic-y += auxvec.h
 generic-y += bitsperlong.h
 generic-y += cputime.h
 generic-y += current.h
+generic-y += early_ioremap.h
 generic-y += emergency-restart.h
 generic-y += errno.h
 generic-y += exec.h
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 3d23418..7b8a981 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -28,6 +28,7 @@
 #include <asm/byteorder.h>
 #include <asm/memory.h>
 #include <asm-generic/pci_iomap.h>
+#include <asm/early_ioremap.h>
 #include <xen/xen.h>
 
 /*
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 8a16ee5..aa2621a 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -36,6 +36,7 @@
 #include <asm/cpu.h>
 #include <asm/cputype.h>
 #include <asm/elf.h>
+#include <asm/io.h>
 #include <asm/procinfo.h>
 #include <asm/psci.h>
 #include <asm/sections.h>
@@ -894,6 +895,8 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
+	early_ioremap_init();
+
 	early_paging_init(mdesc, lookup_processor_type(read_cpuid_id()));
 	setup_dma_zone(mdesc);
 	sanity_check_meminfo();
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 91da64d..1c8ce752 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_ARM_PTDUMP)	+= dump.o
 obj-$(CONFIG_MODULES)		+= proc-syms.o
 
 obj-$(CONFIG_ALIGNMENT_TRAP)	+= alignment.o
+obj-$(CONFIG_EARLY_IOREMAP)	+= early_ioremap.o
 obj-$(CONFIG_HIGHMEM)		+= highmem.o
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
 
diff --git a/arch/arm/mm/early_ioremap.c b/arch/arm/mm/early_ioremap.c
new file mode 100644
index 0000000..1013109
--- /dev/null
+++ b/arch/arm/mm/early_ioremap.c
@@ -0,0 +1,86 @@
+/*
+ * early_ioremap() support for ARM
+ *
+ * Based on existing support in arch/x86/mm/ioremap.c
+ *
+ * Restrictions: currently only functional before paging_init()
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+
+#include <asm/fixmap.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+#include <asm/mach/map.h>
+
+static pte_t bm_pte[PTRS_PER_PTE] __aligned(PTE_HWTABLE_SIZE) __initdata;
+
+static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
+{
+	unsigned int index = pgd_index(addr);
+	pgd_t *pgd = cpu_get_pgd() + index;
+	pud_t *pud = pud_offset(pgd, addr);
+	pmd_t *pmd = pmd_offset(pud, addr);
+
+	return pmd;
+}
+
+static inline pte_t * __init early_ioremap_pte(unsigned long addr)
+{
+	return &bm_pte[pte_index(addr)];
+}
+
+void __init early_ioremap_init(void)
+{
+	pmd_t *pmd;
+
+	pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
+	pmd_populate_kernel(NULL, pmd, bm_pte);
+
+	if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
+		WARN_ON(1);
+		pr_warn("pmd %p != %p\n",
+			pmd, early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END)));
+		pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
+			fix_to_virt(FIX_BTMAP_BEGIN));
+		pr_warn("fix_to_virt(FIX_BTMAP_END):   %08lx\n",
+			fix_to_virt(FIX_BTMAP_END));
+		pr_warn("FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
+		pr_warn("FIX_BTMAP_BEGIN:     %d\n", FIX_BTMAP_BEGIN);
+	}
+
+	early_ioremap_setup();
+}
+
+void __init __early_set_fixmap(enum fixed_addresses idx,
+			       phys_addr_t phys, pgprot_t flags)
+{
+	unsigned long addr = __fix_to_virt(idx);
+	pte_t *pte;
+	u64 desc;
+
+	if (idx > FIX_KMAP_END) {
+		BUG();
+		return;
+	}
+	pte = early_ioremap_pte(addr);
+
+	if (pgprot_val(flags))
+		set_pte_at(NULL, addr, pte,
+			   pfn_pte(phys >> PAGE_SHIFT, flags));
+	else
+		pte_clear(NULL, addr, pte);
+	flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+	desc = *pte;
+}
+
+void __init
+early_ioremap_shutdown(void)
+{
+	pmd_t *pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
+
+	pmd_clear(pmd);
+}
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index ab14b79..608dc36 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -36,6 +36,7 @@
 #include <asm/mach/map.h>
 #include <asm/mach/pci.h>
 #include <asm/fixmap.h>
+#include <asm/early_ioremap.h>
 
 #include "mm.h"
 #include "tcm.h"
@@ -1474,6 +1475,7 @@ void __init paging_init(const struct machine_desc *mdesc)
 {
 	void *zero_page;
 
+	early_ioremap_reset();
 	build_mem_type_table();
 	prepare_page_table();
 	map_lowmem();
-- 
1.7.10.4

[PATCH 0/2] arm: add early_ioremap support

[Russell King - ARM Linux]

On Wed, Jul 09, 2014 at 10:39:50AM +0100, Leif Lindholm wrote:
> early_ioremap()/early_memremap() create temporary virtual mappings
> in the fixmap region during boot time. Part of the support now exists
> in core code, but depends on the generic fixmap support.

Does this mean that the changes upon which this patch depends are
already merged in mainline, or are they queued in some other tree?

Thanks.

-- 
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.

[PATCH 0/2] arm: add early_ioremap support

[Will Deacon]

On Wed, Jul 09, 2014 at 10:39:50AM +0100, Leif Lindholm wrote:
> early_ioremap()/early_memremap() create temporary virtual mappings
> in the fixmap region during boot time. Part of the support now exists
> in core code, but depends on the generic fixmap support.
> 
> This set converts arm to use the generic fixmap support, and adds the
> architecture-specific part of early_ioremap support.
> 
> The fixmap/kmap changes in 3.15 complicated things slightly compared
> to previous iterations of these patches - this version works around
> that by introducing local macros in arm/mm/highmem.c.
> 
> Tested on TC2 and software models, with/without LPAE.
> 
> Mark Salter (2):
>   arm: use generic fixmap.h
>   arm: add early_ioremap support

Curious: why are you sending these patches instead of Mark?

Will

[PATCH 2/2] arm: add early_ioremap support

[Russell King - ARM Linux]

On Wed, Jul 09, 2014 at 10:39:52AM +0100, Leif Lindholm wrote:
> +config EARLY_IOREMAP
> +	depends on MMU
> +	bool "Provide early_ioremap() support for kernel initialization."
> +	select GENERIC_EARLY_IOREMAP

Nit: please order as bool, then depends, then select.

> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index 8a16ee5..aa2621a 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -36,6 +36,7 @@
>  #include <asm/cpu.h>
>  #include <asm/cputype.h>
>  #include <asm/elf.h>
> +#include <asm/io.h>

Please always use linux/io.h in preference to asm/io.h.

> +static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
> +{
> +	unsigned int index = pgd_index(addr);
> +	pgd_t *pgd = cpu_get_pgd() + index;

What is the reasoning for using cpu_get_pgd() ?  Is there some specific
reason you want to read from the hardware register rather than using
the pgd_offset_k() macro here?

> +void __init
> +early_ioremap_shutdown(void)

Nit: should be a single line.

The rest of the patch looks fine, thanks.

-- 
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.

[PATCH 0/2] arm: add early_ioremap support

[Leif Lindholm]

On Wed, Jul 09, 2014 at 10:42:42AM +0100, Russell King - ARM Linux wrote:
> On Wed, Jul 09, 2014 at 10:39:50AM +0100, Leif Lindholm wrote:
> > early_ioremap()/early_memremap() create temporary virtual mappings
> > in the fixmap region during boot time. Part of the support now exists
> > in core code, but depends on the generic fixmap support.
> 
> Does this mean that the changes upon which this patch depends are
> already merged in mainline, or are they queued in some other tree?

Yes, they went into 3.15.

/
    Leif

[PATCH 0/2] arm: add early_ioremap support

[Leif Lindholm]

On Wed, Jul 09, 2014 at 10:47:30AM +0100, Will Deacon wrote:
> On Wed, Jul 09, 2014 at 10:39:50AM +0100, Leif Lindholm wrote:
> > early_ioremap()/early_memremap() create temporary virtual mappings
> > in the fixmap region during boot time. Part of the support now exists
> > in core code, but depends on the generic fixmap support.
> > 
> > This set converts arm to use the generic fixmap support, and adds the
> > architecture-specific part of early_ioremap support.
> > 
> > The fixmap/kmap changes in 3.15 complicated things slightly compared
> > to previous iterations of these patches - this version works around
> > that by introducing local macros in arm/mm/highmem.c.
> > 
> > Tested on TC2 and software models, with/without LPAE.
> > 
> > Mark Salter (2):
> >   arm: use generic fixmap.h
> >   arm: add early_ioremap support
> 
> Curious: why are you sending these patches instead of Mark?

Well, it used to form part of the larger UEFI patchset, which I'm
still marshalling the 32-bit parts of (and which will follow later,
but I will treat them separately from here on).
Also, I did the hacky rework to Mark's original patches for the kmap
changes.

/
    Leif

[PATCH 2/2] arm: add early_ioremap support

[Leif Lindholm]

Hi Russell,

On Wed, Jul 09, 2014 at 10:49:26AM +0100, Russell King - ARM Linux wrote:
> On Wed, Jul 09, 2014 at 10:39:52AM +0100, Leif Lindholm wrote:
> > +config EARLY_IOREMAP
> > +	depends on MMU
> > +	bool "Provide early_ioremap() support for kernel initialization."
> > +	select GENERIC_EARLY_IOREMAP
> 
> Nit: please order as bool, then depends, then select.

Fixed in attached.

> > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> > index 8a16ee5..aa2621a 100644
> > --- a/arch/arm/kernel/setup.c
> > +++ b/arch/arm/kernel/setup.c
> > @@ -36,6 +36,7 @@
> >  #include <asm/cpu.h>
> >  #include <asm/cputype.h>
> >  #include <asm/elf.h>
> > +#include <asm/io.h>
> 
> Please always use linux/io.h in preference to asm/io.h.

Fixed in attached.
 
> > +static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
> > +{
> > +	unsigned int index = pgd_index(addr);
> > +	pgd_t *pgd = cpu_get_pgd() + index;
> 
> What is the reasoning for using cpu_get_pgd() ?  Is there some specific
> reason you want to read from the hardware register rather than using
> the pgd_offset_k() macro here?

No, merely picked the wrong interface, and it seemed to work.
Fixed in attached.

> > +void __init
> > +early_ioremap_shutdown(void)
> 
> Nit: should be a single line.

Fixed in attached.
 
> The rest of the patch looks fine, thanks.

Thank you for your comments.

/
    Leif

>From 6937e88fc0bc62e125d891889334b6659f2efd28 Mon Sep 17 00:00:00 2001
From: Mark Salter <msalter@redhat.com>
Date: Wed, 27 Nov 2013 10:21:11 -0500
Subject: [PATCH 2/2] arm: add early_ioremap support

This patch uses the generic early_ioremap code to implement
early_ioremap for ARM. The ARM-specific bits come mostly from
an earlier patch from Leif Lindholm <leif.lindholm@linaro.org>
here:

  https://lkml.org/lkml/2013/10/3/279

Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
CC: linux-arm-kernel at lists.infradead.org
CC: Russell King <linux@arm.linux.org.uk>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm/Kconfig            |   11 ++++++
 arch/arm/include/asm/Kbuild |    1 +
 arch/arm/include/asm/io.h   |    1 +
 arch/arm/kernel/setup.c     |    3 ++
 arch/arm/mm/Makefile        |    1 +
 arch/arm/mm/early_ioremap.c |   84 +++++++++++++++++++++++++++++++++++++++++++
 arch/arm/mm/mmu.c           |    2 ++
 7 files changed, 103 insertions(+)
 create mode 100644 arch/arm/mm/early_ioremap.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 245058b..5ddafaf 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1800,6 +1800,17 @@ config UACCESS_WITH_MEMCPY
 	  However, if the CPU data cache is using a write-allocate mode,
 	  this option is unlikely to provide any performance gain.
 
+config EARLY_IOREMAP
+	bool "Provide early_ioremap() support for kernel initialization."
+	depends on MMU
+	select GENERIC_EARLY_IOREMAP
+	help
+	  Provide a mechanism for kernel initialisation code to temporarily
+	  map, in a highmem-agnostic way, memory pages in before ioremap()
+	  and friends are available (before paging_init() has run). It uses
+	  the same virtual memory range as kmap so all early mappings must
+	  be unmapped before paging_init() is called.
+
 config SECCOMP
 	bool
 	prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index f5a3576..0bc5a02 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -4,6 +4,7 @@ generic-y += auxvec.h
 generic-y += bitsperlong.h
 generic-y += cputime.h
 generic-y += current.h
+generic-y += early_ioremap.h
 generic-y += emergency-restart.h
 generic-y += errno.h
 generic-y += exec.h
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 3d23418..7b8a981 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -28,6 +28,7 @@
 #include <asm/byteorder.h>
 #include <asm/memory.h>
 #include <asm-generic/pci_iomap.h>
+#include <asm/early_ioremap.h>
 #include <xen/xen.h>
 
 /*
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 8a16ee5..b1f397c 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -30,6 +30,7 @@
 #include <linux/bug.h>
 #include <linux/compiler.h>
 #include <linux/sort.h>
+#include <linux/io.h>
 
 #include <asm/unified.h>
 #include <asm/cp15.h>
@@ -894,6 +895,8 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
+	early_ioremap_init();
+
 	early_paging_init(mdesc, lookup_processor_type(read_cpuid_id()));
 	setup_dma_zone(mdesc);
 	sanity_check_meminfo();
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 91da64d..1c8ce752 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_ARM_PTDUMP)	+= dump.o
 obj-$(CONFIG_MODULES)		+= proc-syms.o
 
 obj-$(CONFIG_ALIGNMENT_TRAP)	+= alignment.o
+obj-$(CONFIG_EARLY_IOREMAP)	+= early_ioremap.o
 obj-$(CONFIG_HIGHMEM)		+= highmem.o
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
 
diff --git a/arch/arm/mm/early_ioremap.c b/arch/arm/mm/early_ioremap.c
new file mode 100644
index 0000000..6444454
--- /dev/null
+++ b/arch/arm/mm/early_ioremap.c
@@ -0,0 +1,84 @@
+/*
+ * early_ioremap() support for ARM
+ *
+ * Based on existing support in arch/x86/mm/ioremap.c
+ *
+ * Restrictions: currently only functional before paging_init()
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+
+#include <asm/fixmap.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+#include <asm/mach/map.h>
+
+static pte_t bm_pte[PTRS_PER_PTE] __aligned(PTE_HWTABLE_SIZE) __initdata;
+
+static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
+{
+	pgd_t *pgd = pgd_offset_k(addr);
+	pud_t *pud = pud_offset(pgd, addr);
+	pmd_t *pmd = pmd_offset(pud, addr);
+
+	return pmd;
+}
+
+static inline pte_t * __init early_ioremap_pte(unsigned long addr)
+{
+	return &bm_pte[pte_index(addr)];
+}
+
+void __init early_ioremap_init(void)
+{
+	pmd_t *pmd;
+
+	pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
+	pmd_populate_kernel(NULL, pmd, bm_pte);
+
+	if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
+		WARN_ON(1);
+		pr_warn("pmd %p != %p\n",
+			pmd, early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END)));
+		pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
+			fix_to_virt(FIX_BTMAP_BEGIN));
+		pr_warn("fix_to_virt(FIX_BTMAP_END):   %08lx\n",
+			fix_to_virt(FIX_BTMAP_END));
+		pr_warn("FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
+		pr_warn("FIX_BTMAP_BEGIN:     %d\n", FIX_BTMAP_BEGIN);
+	}
+
+	early_ioremap_setup();
+}
+
+void __init __early_set_fixmap(enum fixed_addresses idx,
+			       phys_addr_t phys, pgprot_t flags)
+{
+	unsigned long addr = __fix_to_virt(idx);
+	pte_t *pte;
+	u64 desc;
+
+	if (idx > FIX_KMAP_END) {
+		BUG();
+		return;
+	}
+	pte = early_ioremap_pte(addr);
+
+	if (pgprot_val(flags))
+		set_pte_at(NULL, addr, pte,
+			   pfn_pte(phys >> PAGE_SHIFT, flags));
+	else
+		pte_clear(NULL, addr, pte);
+	flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+	desc = *pte;
+}
+
+void __init early_ioremap_shutdown(void)
+{
+	pmd_t *pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
+
+	pmd_clear(pmd);
+}
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index ab14b79..608dc36 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -36,6 +36,7 @@
 #include <asm/mach/map.h>
 #include <asm/mach/pci.h>
 #include <asm/fixmap.h>
+#include <asm/early_ioremap.h>
 
 #include "mm.h"
 #include "tcm.h"
@@ -1474,6 +1475,7 @@ void __init paging_init(const struct machine_desc *mdesc)
 {
 	void *zero_page;
 
+	early_ioremap_reset();
 	build_mem_type_table();
 	prepare_page_table();
 	map_lowmem();
-- 
1.7.10.4

[PATCH 1/2] arm: use generic fixmap.h

[Mark Salter]

On Wed, 2014-07-09 at 10:39 +0100, Leif Lindholm wrote:
> From: Mark Salter <msalter@redhat.com>
> 
> ARM is different from other architectures in that fixmap pages are
> indexed with a positive offset from FIXADDR_START. Other architectures
> index with a negative offset from FIXADDR_TOP. In order to use the
> generic fixmap.h definitions, this patch redefines FIXADDR_TOP to be
> inclusive of the useable range. That is, FIXADDR_TOP is the virtual
> address of the topmost fixed page. The newly defined FIXADDR_END is
> the first virtual address past the fixed mappings.
> 
> The patch also introduces local helper macros in highmem.c to reverse
> the iteration order of fixmap pages.
> 
> Signed-off-by: Mark Salter <msalter@redhat.com>
> [Rebased to 3.16-rc4, reverse kmap fixmap traversal]
> Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
> ---
>  arch/arm/include/asm/fixmap.h |   45 ++++++++++++++++++++++++++---------------
>  arch/arm/mm/highmem.c         |   13 +++++++-----
>  arch/arm/mm/init.c            |    2 +-
>  3 files changed, 38 insertions(+), 22 deletions(-)
> 
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index 74124b0..8992431 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -1,28 +1,41 @@
>  #ifndef _ASM_FIXMAP_H
>  #define _ASM_FIXMAP_H
>  
> +#include <asm/pgtable.h>
> +
>  #define FIXADDR_START		0xffc00000UL
> -#define FIXADDR_TOP		0xffe00000UL
> -#define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
> +#define FIXADDR_END		0xffe00000UL
> +#define FIXADDR_SIZE		(FIXADDR_END - FIXADDR_START)
> +#define FIXADDR_TOP		(FIXADDR_END - PAGE_SIZE)
>  
>  #define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
>  
> -#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
> -#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
> +enum fixed_addresses {
> +	FIX_KMAP_BEGIN,
> +	FIX_KMAP_END = FIX_KMAP_NR_PTES - 1,
> +	__end_of_fixed_addresses
> +};
> +
> +/*
> + * Temporary boot-time mappings, used by early_ioremap(),
> + * before ioremap() is functional.
> + *
> + * (P)re-using the last pmd of the FIXADDR region, which is used for
> + * highmem later on, and statically aligned to 1MB.
> + * Growing down from FIXADDR_TOP
> + */
> +#define NR_FIX_BTMAPS		32
> +#define FIX_BTMAPS_SLOTS	(PTRS_PER_PTE / NR_FIX_BTMAPS)
> +#define TOTAL_FIX_BTMAPS	(NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
> +#define FIX_BTMAP_END		FIX_KMAP_BEGIN
> +#define FIX_BTMAP_BEGIN		(FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1)
>  
> -extern void __this_fixmap_does_not_exist(void);
> +#define FIXMAP_PAGE_NORMAL (L_PTE_MT_WRITEBACK | L_PTE_YOUNG | L_PTE_PRESENT)
> +#define FIXMAP_PAGE_IO (L_PTE_MT_DEV_NONSHARED | L_PTE_YOUNG | L_PTE_PRESENT)
>  
> -static inline unsigned long fix_to_virt(const unsigned int idx)
> -{
> -	if (idx >= FIX_KMAP_NR_PTES)
> -		__this_fixmap_does_not_exist();
> -	return __fix_to_virt(idx);
> -}
> +extern void __early_set_fixmap(enum fixed_addresses idx,
> +			       phys_addr_t phys, pgprot_t flags);
>  
> -static inline unsigned int virt_to_fix(const unsigned long vaddr)
> -{
> -	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
> -	return __virt_to_fix(vaddr);
> -}
> +#include <asm-generic/fixmap.h>
>  
>  #endif
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index 45aeaac..3c59cdf 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -20,16 +20,19 @@
>  
>  pte_t *fixmap_page_table;
>  
> +#define __kmap_fix_to_virt(x)	(__fix_to_virt(FIX_KMAP_NR_PTES - 1 - (x)))

FIX_KMAP_END - (x) ?

> +#define __kmap_virt_to_fix(x)	(FIX_KMAP_NR_PTES - 1 - __fix_to_virt(x))

shouldn't this use __virt_to_fix(x)?

> +
>  static inline void set_fixmap_pte(int idx, pte_t pte)
>  {
> -	unsigned long vaddr = __fix_to_virt(idx);
> +	unsigned long vaddr = __kmap_fix_to_virt(idx);
>  	set_pte_ext(fixmap_page_table + idx, pte, 0);
>  	local_flush_tlb_kernel_page(vaddr);
>  }
>  
>  static inline pte_t get_fixmap_pte(unsigned long vaddr)
>  {
> -	unsigned long idx = __virt_to_fix(vaddr);
> +	unsigned long idx = __kmap_virt_to_fix(vaddr);
>  	return *(fixmap_page_table + idx);
>  }
>  
> @@ -78,7 +81,7 @@ void *kmap_atomic(struct page *page)
>  	type = kmap_atomic_idx_push();
>  
>  	idx = type + KM_TYPE_NR * smp_processor_id();
> -	vaddr = __fix_to_virt(idx);
> +	vaddr = __kmap_fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>  	/*
>  	 * With debugging enabled, kunmap_atomic forces that entry to 0.
> @@ -109,7 +112,7 @@ void __kunmap_atomic(void *kvaddr)
>  		if (cache_is_vivt())
>  			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>  #ifdef CONFIG_DEBUG_HIGHMEM
> -		BUG_ON(vaddr != __fix_to_virt(idx));
> +		BUG_ON(vaddr != __kmap_fix_to_virt(idx));
>  		set_fixmap_pte(idx, __pte(0));
>  #else
>  		(void) idx;  /* to kill a warning */
> @@ -132,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
>  
>  	type = kmap_atomic_idx_push();
>  	idx = type + KM_TYPE_NR * smp_processor_id();
> -	vaddr = __fix_to_virt(idx);
> +	vaddr = __kmap_fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>  	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
>  #endif
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 659c75d..ad82c05 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -570,7 +570,7 @@ void __init mem_init(void)
>  			MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
>  			MLK(ITCM_OFFSET, (unsigned long) itcm_end),
>  #endif
> -			MLK(FIXADDR_START, FIXADDR_TOP),
> +			MLK(FIXADDR_START, FIXADDR_END),
>  			MLM(VMALLOC_START, VMALLOC_END),
>  			MLM(PAGE_OFFSET, (unsigned long)high_memory),
>  #ifdef CONFIG_HIGHMEM

[PATCH 1/2] arm: use generic fixmap.h

[Leif Lindholm]

On Wed, Jul 09, 2014 at 04:49:02PM -0400, Mark Salter wrote:
> On Wed, 2014-07-09 at 10:39 +0100, Leif Lindholm wrote:
> > diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> > index 45aeaac..3c59cdf 100644
> > --- a/arch/arm/mm/highmem.c
> > +++ b/arch/arm/mm/highmem.c
> > @@ -20,16 +20,19 @@
> >  
> >  pte_t *fixmap_page_table;
> >  
> > +#define __kmap_fix_to_virt(x)	(__fix_to_virt(FIX_KMAP_NR_PTES - 1 - (x)))
> 
> FIX_KMAP_END - (x) ?
> 
> > +#define __kmap_virt_to_fix(x)	(FIX_KMAP_NR_PTES - 1 - __fix_to_virt(x))
> 
> shouldn't this use __virt_to_fix(x)?

Err, clearly.
Good thing I managed to mess up the end of the interface that actually
isn't used anywhere in the kernel(!).

Fixed in the below.

/
    Leif

>From d0a82cd19000139d32232f415bcf46f476c16561 Mon Sep 17 00:00:00 2001
From: Mark Salter <msalter@redhat.com>
Date: Thu, 14 Nov 2013 11:37:32 -0500
Subject: [PATCH 1/2] arm: use generic fixmap.h

ARM is different from other architectures in that fixmap pages are
indexed with a positive offset from FIXADDR_START. Other architectures
index with a negative offset from FIXADDR_TOP. In order to use the
generic fixmap.h definitions, this patch redefines FIXADDR_TOP to be
inclusive of the useable range. That is, FIXADDR_TOP is the virtual
address of the topmost fixed page. The newly defined FIXADDR_END is
the first virtual address past the fixed mappings.

The patch also introduces local helper macros in highmem.c to reverse
the iteration order of fixmap pages.

Signed-off-by: Mark Salter <msalter@redhat.com>
[Rebased to 3.16-rc4, reverse kmap fixmap traversal]
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
---
 arch/arm/include/asm/fixmap.h |   45 ++++++++++++++++++++++++++---------------
 arch/arm/mm/highmem.c         |   13 +++++++-----
 arch/arm/mm/init.c            |    2 +-
 3 files changed, 38 insertions(+), 22 deletions(-)

diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
index 74124b0..8992431 100644
--- a/arch/arm/include/asm/fixmap.h
+++ b/arch/arm/include/asm/fixmap.h
@@ -1,28 +1,41 @@
 #ifndef _ASM_FIXMAP_H
 #define _ASM_FIXMAP_H
 
+#include <asm/pgtable.h>
+
 #define FIXADDR_START		0xffc00000UL
-#define FIXADDR_TOP		0xffe00000UL
-#define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
+#define FIXADDR_END		0xffe00000UL
+#define FIXADDR_SIZE		(FIXADDR_END - FIXADDR_START)
+#define FIXADDR_TOP		(FIXADDR_END - PAGE_SIZE)
 
 #define FIX_KMAP_NR_PTES	(FIXADDR_SIZE >> PAGE_SHIFT)
 
-#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
-#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
+enum fixed_addresses {
+	FIX_KMAP_BEGIN,
+	FIX_KMAP_END = FIX_KMAP_NR_PTES - 1,
+	__end_of_fixed_addresses
+};
+
+/*
+ * Temporary boot-time mappings, used by early_ioremap(),
+ * before ioremap() is functional.
+ *
+ * (P)re-using the last pmd of the FIXADDR region, which is used for
+ * highmem later on, and statically aligned to 1MB.
+ * Growing down from FIXADDR_TOP
+ */
+#define NR_FIX_BTMAPS		32
+#define FIX_BTMAPS_SLOTS	(PTRS_PER_PTE / NR_FIX_BTMAPS)
+#define TOTAL_FIX_BTMAPS	(NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
+#define FIX_BTMAP_END		FIX_KMAP_BEGIN
+#define FIX_BTMAP_BEGIN		(FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1)
 
-extern void __this_fixmap_does_not_exist(void);
+#define FIXMAP_PAGE_NORMAL (L_PTE_MT_WRITEBACK | L_PTE_YOUNG | L_PTE_PRESENT)
+#define FIXMAP_PAGE_IO (L_PTE_MT_DEV_NONSHARED | L_PTE_YOUNG | L_PTE_PRESENT)
 
-static inline unsigned long fix_to_virt(const unsigned int idx)
-{
-	if (idx >= FIX_KMAP_NR_PTES)
-		__this_fixmap_does_not_exist();
-	return __fix_to_virt(idx);
-}
+extern void __early_set_fixmap(enum fixed_addresses idx,
+			       phys_addr_t phys, pgprot_t flags);
 
-static inline unsigned int virt_to_fix(const unsigned long vaddr)
-{
-	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
-	return __virt_to_fix(vaddr);
-}
+#include <asm-generic/fixmap.h>
 
 #endif
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index 45aeaac..2e5b773 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -20,16 +20,19 @@
 
 pte_t *fixmap_page_table;
 
+#define __kmap_fix_to_virt(x)	(__fix_to_virt(FIX_KMAP_NR_PTES - 1 - (x)))
+#define __kmap_virt_to_fix(x)	(FIX_KMAP_NR_PTES - 1 - __virt_to_fix(x))
+
 static inline void set_fixmap_pte(int idx, pte_t pte)
 {
-	unsigned long vaddr = __fix_to_virt(idx);
+	unsigned long vaddr = __kmap_fix_to_virt(idx);
 	set_pte_ext(fixmap_page_table + idx, pte, 0);
 	local_flush_tlb_kernel_page(vaddr);
 }
 
 static inline pte_t get_fixmap_pte(unsigned long vaddr)
 {
-	unsigned long idx = __virt_to_fix(vaddr);
+	unsigned long idx = __kmap_virt_to_fix(vaddr);
 	return *(fixmap_page_table + idx);
 }
 
@@ -78,7 +81,7 @@ void *kmap_atomic(struct page *page)
 	type = kmap_atomic_idx_push();
 
 	idx = type + KM_TYPE_NR * smp_processor_id();
-	vaddr = __fix_to_virt(idx);
+	vaddr = __kmap_fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
 	/*
 	 * With debugging enabled, kunmap_atomic forces that entry to 0.
@@ -109,7 +112,7 @@ void __kunmap_atomic(void *kvaddr)
 		if (cache_is_vivt())
 			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 #ifdef CONFIG_DEBUG_HIGHMEM
-		BUG_ON(vaddr != __fix_to_virt(idx));
+		BUG_ON(vaddr != __kmap_fix_to_virt(idx));
 		set_fixmap_pte(idx, __pte(0));
 #else
 		(void) idx;  /* to kill a warning */
@@ -132,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR * smp_processor_id();
-	vaddr = __fix_to_virt(idx);
+	vaddr = __kmap_fix_to_virt(idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
 	BUG_ON(!pte_none(*(fixmap_page_table + idx)));
 #endif
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 659c75d..ad82c05 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -570,7 +570,7 @@ void __init mem_init(void)
 			MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
 			MLK(ITCM_OFFSET, (unsigned long) itcm_end),
 #endif
-			MLK(FIXADDR_START, FIXADDR_TOP),
+			MLK(FIXADDR_START, FIXADDR_END),
 			MLM(VMALLOC_START, VMALLOC_END),
 			MLM(PAGE_OFFSET, (unsigned long)high_memory),
 #ifdef CONFIG_HIGHMEM
-- 
1.7.10.4

[PATCH 1/2] arm: use generic fixmap.h

[Tomasz Figa]

Hi Leif,

On 09.07.2014 11:39, Leif Lindholm wrote:
> From: Mark Salter <msalter@redhat.com>
> 
> ARM is different from other architectures in that fixmap pages are
> indexed with a positive offset from FIXADDR_START. Other architectures
> index with a negative offset from FIXADDR_TOP. In order to use the
> generic fixmap.h definitions, this patch redefines FIXADDR_TOP to be
> inclusive of the useable range. That is, FIXADDR_TOP is the virtual
> address of the topmost fixed page. The newly defined FIXADDR_END is
> the first virtual address past the fixed mappings.
> 
> The patch also introduces local helper macros in highmem.c to reverse
> the iteration order of fixmap pages.
> 
> Signed-off-by: Mark Salter <msalter@redhat.com>
> [Rebased to 3.16-rc4, reverse kmap fixmap traversal]
> Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
> ---
>  arch/arm/include/asm/fixmap.h |   45 ++++++++++++++++++++++++++---------------
>  arch/arm/mm/highmem.c         |   13 +++++++-----
>  arch/arm/mm/init.c            |    2 +-
>  3 files changed, 38 insertions(+), 22 deletions(-)
> 

I've tried to use this series to enable earlycon without hardcoded
static mappings, but apparently something is not right yet. Please see
below.

[snip]

> -extern void __this_fixmap_does_not_exist(void);
> +#define FIXMAP_PAGE_NORMAL (L_PTE_MT_WRITEBACK | L_PTE_YOUNG | L_PTE_PRESENT)
> +#define FIXMAP_PAGE_IO (L_PTE_MT_DEV_NONSHARED | L_PTE_YOUNG | L_PTE_PRESENT)

This set of flags gives a read-only mapping on the machine I'm testing
on (Exynos4412, Cortex A9MPcore). If I use the same set of flags as used
in arch/arm/mm/mmu.c for MT_DEVICE_NONSHARED then the mapping works fine.

Best regards,
Tomasz

[PATCH 2/2] arm: add early_ioremap support

[Tomasz Figa]

Hi Leif,

On 09.07.2014 11:39, Leif Lindholm wrote:
> From: Mark Salter <msalter@redhat.com>
> 
> This patch uses the generic early_ioremap code to implement
> early_ioremap for ARM. The ARM-specific bits come mostly from
> an earlier patch from Leif Lindholm <leif.lindholm@linaro.org>
> here:
> 
>   https://lkml.org/lkml/2013/10/3/279

[snip]

> diff --git a/arch/arm/mm/early_ioremap.c b/arch/arm/mm/early_ioremap.c
> new file mode 100644
> index 0000000..1013109
> --- /dev/null
> +++ b/arch/arm/mm/early_ioremap.c
> @@ -0,0 +1,86 @@
> +/*
> + * early_ioremap() support for ARM
> + *
> + * Based on existing support in arch/x86/mm/ioremap.c
> + *
> + * Restrictions: currently only functional before paging_init()

Uhm, that's bad... This would explain why my earlycon code generates a
fault as soon as something prints after paging_init(). I'd say this
feature would be much more useful if mappings were carried over
paging_init(), so that mapped devices are available later as well.

I'll see if I can code this on top of your patch, but unfortunately it
might end up with -ENOTIME.

Best regards,
Tomasz

[PATCH 2/2] arm: add early_ioremap support

[Rob Herring]

On Tue, Jul 22, 2014 at 11:48 AM, Tomasz Figa <t.figa@samsung.com> wrote:
> Hi Leif,
>
> On 09.07.2014 11:39, Leif Lindholm wrote:
>> From: Mark Salter <msalter@redhat.com>
>>
>> This patch uses the generic early_ioremap code to implement
>> early_ioremap for ARM. The ARM-specific bits come mostly from
>> an earlier patch from Leif Lindholm <leif.lindholm@linaro.org>
>> here:
>>
>>   https://lkml.org/lkml/2013/10/3/279
>
> [snip]
>
>> diff --git a/arch/arm/mm/early_ioremap.c b/arch/arm/mm/early_ioremap.c
>> new file mode 100644
>> index 0000000..1013109
>> --- /dev/null
>> +++ b/arch/arm/mm/early_ioremap.c
>> @@ -0,0 +1,86 @@
>> +/*
>> + * early_ioremap() support for ARM
>> + *
>> + * Based on existing support in arch/x86/mm/ioremap.c
>> + *
>> + * Restrictions: currently only functional before paging_init()
>
> Uhm, that's bad... This would explain why my earlycon code generates a
> fault as soon as something prints after paging_init(). I'd say this
> feature would be much more useful if mappings were carried over
> paging_init(), so that mapped devices are available later as well.
>
> I'll see if I can code this on top of your patch, but unfortunately it
> might end up with -ENOTIME.

I have fixmap support that's needed for earlycon. Here is the branch:

git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git fixmap

It is based on an earlier version of patchset and not on the latest
version from Leif. Unfortunately, I don't have more time to spend on
it ATM.

Rob

[PATCH 2/2] arm: add early_ioremap support

[Tomasz Figa]

On 22.07.2014 19:11, Rob Herring wrote:
> On Tue, Jul 22, 2014 at 11:48 AM, Tomasz Figa <t.figa@samsung.com> wrote:
>> Hi Leif,
>>
>> On 09.07.2014 11:39, Leif Lindholm wrote:
>>> From: Mark Salter <msalter@redhat.com>
>>>
>>> This patch uses the generic early_ioremap code to implement
>>> early_ioremap for ARM. The ARM-specific bits come mostly from
>>> an earlier patch from Leif Lindholm <leif.lindholm@linaro.org>
>>> here:
>>>
>>>   https://lkml.org/lkml/2013/10/3/279
>>
>> [snip]
>>
>>> diff --git a/arch/arm/mm/early_ioremap.c b/arch/arm/mm/early_ioremap.c
>>> new file mode 100644
>>> index 0000000..1013109
>>> --- /dev/null
>>> +++ b/arch/arm/mm/early_ioremap.c
>>> @@ -0,0 +1,86 @@
>>> +/*
>>> + * early_ioremap() support for ARM
>>> + *
>>> + * Based on existing support in arch/x86/mm/ioremap.c
>>> + *
>>> + * Restrictions: currently only functional before paging_init()
>>
>> Uhm, that's bad... This would explain why my earlycon code generates a
>> fault as soon as something prints after paging_init(). I'd say this
>> feature would be much more useful if mappings were carried over
>> paging_init(), so that mapped devices are available later as well.
>>
>> I'll see if I can code this on top of your patch, but unfortunately it
>> might end up with -ENOTIME.
> 
> I have fixmap support that's needed for earlycon. Here is the branch:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git fixmap
> 
> It is based on an earlier version of patchset and not on the latest
> version from Leif. Unfortunately, I don't have more time to spend on
> it ATM.

Thanks Rob. I'll give it a try.

Best regards,
Tomasz

[PATCH 1/2] arm: use generic fixmap.h

[Kees Cook]

On Fri, Jul 18, 2014 at 7:33 AM, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> On Wed, Jul 09, 2014 at 04:49:02PM -0400, Mark Salter wrote:
>> On Wed, 2014-07-09 at 10:39 +0100, Leif Lindholm wrote:
>> > diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
>> > index 45aeaac..3c59cdf 100644
>> > --- a/arch/arm/mm/highmem.c
>> > +++ b/arch/arm/mm/highmem.c
>> > @@ -20,16 +20,19 @@
>> >
>> >  pte_t *fixmap_page_table;
>> >
>> > +#define __kmap_fix_to_virt(x)      (__fix_to_virt(FIX_KMAP_NR_PTES - 1 - (x)))
>>
>> FIX_KMAP_END - (x) ?
>>
>> > +#define __kmap_virt_to_fix(x)      (FIX_KMAP_NR_PTES - 1 - __fix_to_virt(x))
>>
>> shouldn't this use __virt_to_fix(x)?
>
> Err, clearly.
> Good thing I managed to mess up the end of the interface that actually
> isn't used anywhere in the kernel(!).
>
> Fixed in the below.
>
> /
>     Leif
>
> From d0a82cd19000139d32232f415bcf46f476c16561 Mon Sep 17 00:00:00 2001
> From: Mark Salter <msalter@redhat.com>
> Date: Thu, 14 Nov 2013 11:37:32 -0500
> Subject: [PATCH 1/2] arm: use generic fixmap.h
>
> ARM is different from other architectures in that fixmap pages are
> indexed with a positive offset from FIXADDR_START. Other architectures
> index with a negative offset from FIXADDR_TOP. In order to use the
> generic fixmap.h definitions, this patch redefines FIXADDR_TOP to be
> inclusive of the useable range. That is, FIXADDR_TOP is the virtual
> address of the topmost fixed page. The newly defined FIXADDR_END is
> the first virtual address past the fixed mappings.
>
> The patch also introduces local helper macros in highmem.c to reverse
> the iteration order of fixmap pages.
>
> Signed-off-by: Mark Salter <msalter@redhat.com>
> [Rebased to 3.16-rc4, reverse kmap fixmap traversal]
> Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
> ---
>  arch/arm/include/asm/fixmap.h |   45 ++++++++++++++++++++++++++---------------
>  arch/arm/mm/highmem.c         |   13 +++++++-----
>  arch/arm/mm/init.c            |    2 +-
>  3 files changed, 38 insertions(+), 22 deletions(-)
>
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index 74124b0..8992431 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -1,28 +1,41 @@
>  #ifndef _ASM_FIXMAP_H
>  #define _ASM_FIXMAP_H
>
> +#include <asm/pgtable.h>
> +
>  #define FIXADDR_START          0xffc00000UL
> -#define FIXADDR_TOP            0xffe00000UL
> -#define FIXADDR_SIZE           (FIXADDR_TOP - FIXADDR_START)
> +#define FIXADDR_END            0xffe00000UL
> +#define FIXADDR_SIZE           (FIXADDR_END - FIXADDR_START)
> +#define FIXADDR_TOP            (FIXADDR_END - PAGE_SIZE)
>
>  #define FIX_KMAP_NR_PTES       (FIXADDR_SIZE >> PAGE_SHIFT)
>
> -#define __fix_to_virt(x)       (FIXADDR_START + ((x) << PAGE_SHIFT))
> -#define __virt_to_fix(x)       (((x) - FIXADDR_START) >> PAGE_SHIFT)
> +enum fixed_addresses {
> +       FIX_KMAP_BEGIN,
> +       FIX_KMAP_END = FIX_KMAP_NR_PTES - 1,
> +       __end_of_fixed_addresses
> +};
> +
> +/*
> + * Temporary boot-time mappings, used by early_ioremap(),
> + * before ioremap() is functional.
> + *
> + * (P)re-using the last pmd of the FIXADDR region, which is used for
> + * highmem later on, and statically aligned to 1MB.
> + * Growing down from FIXADDR_TOP
> + */
> +#define NR_FIX_BTMAPS          32
> +#define FIX_BTMAPS_SLOTS       (PTRS_PER_PTE / NR_FIX_BTMAPS)
> +#define TOTAL_FIX_BTMAPS       (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
> +#define FIX_BTMAP_END          FIX_KMAP_BEGIN
> +#define FIX_BTMAP_BEGIN                (FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1)
>
> -extern void __this_fixmap_does_not_exist(void);
> +#define FIXMAP_PAGE_NORMAL (L_PTE_MT_WRITEBACK | L_PTE_YOUNG | L_PTE_PRESENT)
> +#define FIXMAP_PAGE_IO (L_PTE_MT_DEV_NONSHARED | L_PTE_YOUNG | L_PTE_PRESENT)
>
> -static inline unsigned long fix_to_virt(const unsigned int idx)
> -{
> -       if (idx >= FIX_KMAP_NR_PTES)
> -               __this_fixmap_does_not_exist();
> -       return __fix_to_virt(idx);
> -}
> +extern void __early_set_fixmap(enum fixed_addresses idx,
> +                              phys_addr_t phys, pgprot_t flags);
>
> -static inline unsigned int virt_to_fix(const unsigned long vaddr)
> -{
> -       BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
> -       return __virt_to_fix(vaddr);
> -}
> +#include <asm-generic/fixmap.h>
>
>  #endif
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index 45aeaac..2e5b773 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -20,16 +20,19 @@
>
>  pte_t *fixmap_page_table;
>
> +#define __kmap_fix_to_virt(x)  (__fix_to_virt(FIX_KMAP_NR_PTES - 1 - (x)))
> +#define __kmap_virt_to_fix(x)  (FIX_KMAP_NR_PTES - 1 - __virt_to_fix(x))
> +
>  static inline void set_fixmap_pte(int idx, pte_t pte)
>  {
> -       unsigned long vaddr = __fix_to_virt(idx);
> +       unsigned long vaddr = __kmap_fix_to_virt(idx);
>         set_pte_ext(fixmap_page_table + idx, pte, 0);
>         local_flush_tlb_kernel_page(vaddr);
>  }
>
>  static inline pte_t get_fixmap_pte(unsigned long vaddr)
>  {
> -       unsigned long idx = __virt_to_fix(vaddr);
> +       unsigned long idx = __kmap_virt_to_fix(vaddr);
>         return *(fixmap_page_table + idx);
>  }
>
> @@ -78,7 +81,7 @@ void *kmap_atomic(struct page *page)
>         type = kmap_atomic_idx_push();
>
>         idx = type + KM_TYPE_NR * smp_processor_id();
> -       vaddr = __fix_to_virt(idx);
> +       vaddr = __kmap_fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>         /*
>          * With debugging enabled, kunmap_atomic forces that entry to 0.
> @@ -109,7 +112,7 @@ void __kunmap_atomic(void *kvaddr)
>                 if (cache_is_vivt())
>                         __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
>  #ifdef CONFIG_DEBUG_HIGHMEM
> -               BUG_ON(vaddr != __fix_to_virt(idx));
> +               BUG_ON(vaddr != __kmap_fix_to_virt(idx));
>                 set_fixmap_pte(idx, __pte(0));
>  #else
>                 (void) idx;  /* to kill a warning */
> @@ -132,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
>
>         type = kmap_atomic_idx_push();
>         idx = type + KM_TYPE_NR * smp_processor_id();
> -       vaddr = __fix_to_virt(idx);
> +       vaddr = __kmap_fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
>         BUG_ON(!pte_none(*(fixmap_page_table + idx)));
>  #endif
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 659c75d..ad82c05 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -570,7 +570,7 @@ void __init mem_init(void)
>                         MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
>                         MLK(ITCM_OFFSET, (unsigned long) itcm_end),
>  #endif
> -                       MLK(FIXADDR_START, FIXADDR_TOP),
> +                       MLK(FIXADDR_START, FIXADDR_END),
>                         MLM(VMALLOC_START, VMALLOC_END),
>                         MLM(PAGE_OFFSET, (unsigned long)high_memory),
>  #ifdef CONFIG_HIGHMEM
> --
> 1.7.10.4
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

I'd like to use this for kernel RO text handling too (kprobes and
kgdb). Is this patch alone in good enough shape for landing in -next?
I would want this added as well:
https://patchwork.kernel.org/patch/3941001/

Thoughts?

-Kees

-- 
Kees Cook
Chrome OS Security

[PATCH 0/2] arm: add early_ioremap() support

[Arnd Bergmann]

On Thursday 27 June 2013, Leif Lindholm wrote:
> On Thu, Jun 27, 2013 at 10:47:21AM +0200, Arnd Bergmann wrote:
> > > No, the purpose is just like for x86 - do early parsing of things like
> > > the UEFI system and configuration tables, DMI and ACPI, in order to
> > > populate global structs and stuff.
> > 
> > But are those tables actually in MMIO registers? I thought they
> > are just memory, and in that case using any form of ioremap is
> > wrong on ARM. Why do you even have to map them? Can't the boot
> > loader pass those tables in regular addressable memory?
>  
> Don't get too stuck on the name - x86 frequently uses *ioremap() in
> many places when just accessing memory, and that has carried into EFI,
> ACPI and DMI subsystems, which we now want to use on ARM. In fact, they
> have early_memremap(), but don't use it for either EFI or ACPI.

The difference of course is that x86 doesn't use page table flags
to tell the difference between MMIO and memory. It is not harmful
on x86 to access memory through ioremap, but it is on most
other architectures. You get either unspecified behavior due to
conflicting cache flags or you get a hard checkstop based on how
the CPU treats this. If you want to make the EFI code architecture
independent, I think you should change the EFI code.

> The ia64 implementation actually performs a lookup in the EFI memmap
> to decide whether early_ioremap() returns cacheable memory or not
> (and falls back to noncacheable before memory map is available).
> 
> That said, I had somehow managed to get into my mind that the kernel
> used -fno-unaligned-access, so thought MT_DEV_NONSHARED was safe.
> Clearly it isn't, so that will need to change, making the semantic
> match even worse...
> 
> As for the need of mapping - some of these descriptors are needed very
> early in the boot process. Also, depending on platform, they may reside
> at any offset from start of RAM (<2^32 physical address), rendering
> __va()/__phys_to_virt()/... unusable.

Can you explain why they are needed this early?

Also, can't we define the boot protocol to require these tables
within the first GB of RAM?

> > > Well, I did have a crazy idea that much/most of the early_ioremap code
> > > could be made generic and shared between x86 and arm (and any other
> > > 32-bit architecture). Using the fixmap macros would make that possible
> > > with a minimum of ifdefs.
> > > 
> > > If we ever wanted early_ioremap() to work like on x86, beyond kmap_init()
> > > (but not beyond the "booting" system state), using the same macros would
> > > help there too. I had no need for that for my EFI patches.
> > 
> > I guess I need to look at the EFI patches first. It sounds to me
> > like you shouldn't actually be using early_ioremap here or on another
> > architecture.
> 
> No, but I had been kind of hoping not having to rework the early memory
> initialisation for three subsystems on two other platforms in order to
> be able to merge common code between them. And it would have felt silly
> to invent a new mechanism just for ARM, preventing that option.

Well, if you can get around the "early" requirement, things can become
much easier, you can basically 

#define early_ioremap(addr, size) ioremap(addr, size)
#define early_memremap(addr, size) ioremap_cached(addr, size)

and just need to fix the places where the common code mistakenly calls
early_ioremap instead of early_memremap.

Chances are that even if you can't avoid the requirement for early
maps entirely that you only really have to worry about a small number
of callers, for which you can then introduce architecture specific
functions that do one thing in an appropriate way. On ARM, this may
end up being __va(), kmap_atomic() or iotable_init() depending on
the requirements.

	Arnd

[PATCH 0/2] arm: add early_ioremap() support

[Leif Lindholm]

On Thu, Jun 27, 2013 at 10:47:21AM +0200, Arnd Bergmann wrote:
> > No, the purpose is just like for x86 - do early parsing of things like
> > the UEFI system and configuration tables, DMI and ACPI, in order to
> > populate global structs and stuff.
> 
> But are those tables actually in MMIO registers? I thought they
> are just memory, and in that case using any form of ioremap is
> wrong on ARM. Why do you even have to map them? Can't the boot
> loader pass those tables in regular addressable memory?
 
Don't get too stuck on the name - x86 frequently uses *ioremap() in
many places when just accessing memory, and that has carried into EFI,
ACPI and DMI subsystems, which we now want to use on ARM. In fact, they
have early_memremap(), but don't use it for either EFI or ACPI.

The ia64 implementation actually performs a lookup in the EFI memmap
to decide whether early_ioremap() returns cacheable memory or not
(and falls back to noncacheable before memory map is available).

That said, I had somehow managed to get into my mind that the kernel
used -fno-unaligned-access, so thought MT_DEV_NONSHARED was safe.
Clearly it isn't, so that will need to change, making the semantic
match even worse...

As for the need of mapping - some of these descriptors are needed very
early in the boot process. Also, depending on platform, they may reside
at any offset from start of RAM (<2^32 physical address), rendering
__va()/__phys_to_virt()/... unusable.

> > Well, I did have a crazy idea that much/most of the early_ioremap code
> > could be made generic and shared between x86 and arm (and any other
> > 32-bit architecture). Using the fixmap macros would make that possible
> > with a minimum of ifdefs.
> > 
> > If we ever wanted early_ioremap() to work like on x86, beyond kmap_init()
> > (but not beyond the "booting" system state), using the same macros would
> > help there too. I had no need for that for my EFI patches.
> 
> I guess I need to look at the EFI patches first. It sounds to me
> like you shouldn't actually be using early_ioremap here or on another
> architecture.

No, but I had been kind of hoping not having to rework the early memory
initialisation for three subsystems on two other platforms in order to
be able to merge common code between them. And it would have felt silly
to invent a new mechanism just for ARM, preventing that option.

/
    Leif

[PATCH 0/2] arm: add early_ioremap() support

[Arnd Bergmann]

On Thursday 27 June 2013 01:25:06 Leif Lindholm wrote:
> On Thu, Jun 27, 2013 at 12:13:55AM +0200, Arnd Bergmann wrote:
> > > Sorry, I still don't get it. Are you saying that kmap_atomic is
> > > available before kmap_init() (in paging_init())?
> > > 
> > > If not, all of my mappings are discarded (well, abandoned to be more
> > > correct), so I don't see how it affects kmap.
> > 
> > Sorry, I was under the assumption that the mappings are meant to
> > stay around.
>  
> Ok, just so I'm not completely lost 
> 
> No, the purpose is just like for x86 - do early parsing of things like
> the UEFI system and configuration tables, DMI and ACPI, in order to
> populate global structs and stuff.

But are those tables actually in MMIO registers? I thought they
are just memory, and in that case using any form of ioremap is
wrong on ARM. Why do you even have to map them? Can't the boot
loader pass those tables in regular addressable memory?

> > > Indeed - almost immediately.
> > > 
> > > x86 early_ioremap can coexist with kmap; the intent of my
> > > implementation is to use the kmap region only before kmap is available.
> > 
> > So if you never plan to use fixmap and early_ioremap at the same time,
> > why even bother using the fixmap code? Wouldn't it be easier to just
> > use the same memory area and ensure we never use fixmap before 
> > we're done with early_ioremap?
> 
> Well, I did have a crazy idea that much/most of the early_ioremap code
> could be made generic and shared between x86 and arm (and any other
> 32-bit architecture). Using the fixmap macros would make that possible
> with a minimum of ifdefs.
> 
> If we ever wanted early_ioremap() to work like on x86, beyond kmap_init()
> (but not beyond the "booting" system state), using the same macros would
> help there too. I had no need for that for my EFI patches.

I guess I need to look at the EFI patches first. It sounds to me
like you shouldn't actually be using early_ioremap here or on another
architecture.

	Arnd

[PATCH 0/2] arm: add early_ioremap() support

[Leif Lindholm]

On Thu, Jun 27, 2013 at 12:13:55AM +0200, Arnd Bergmann wrote:
> > Sorry, I still don't get it. Are you saying that kmap_atomic is
> > available before kmap_init() (in paging_init())?
> > 
> > If not, all of my mappings are discarded (well, abandoned to be more
> > correct), so I don't see how it affects kmap.
> 
> Sorry, I was under the assumption that the mappings are meant to
> stay around.
 
Ok, just so I'm not completely lost :)

No, the purpose is just like for x86 - do early parsing of things like
the UEFI system and configuration tables, DMI and ACPI, in order to
populate global structs and stuff.

> > Indeed - almost immediately.
> > 
> > x86 early_ioremap can coexist with kmap; the intent of my
> > implementation is to use the kmap region only before kmap is available.
> 
> So if you never plan to use fixmap and early_ioremap at the same time,
> why even bother using the fixmap code? Wouldn't it be easier to just
> use the same memory area and ensure we never use fixmap before 
> we're done with early_ioremap?

Well, I did have a crazy idea that much/most of the early_ioremap code
could be made generic and shared between x86 and arm (and any other
32-bit architecture). Using the fixmap macros would make that possible
with a minimum of ifdefs.

If we ever wanted early_ioremap() to work like on x86, beyond kmap_init()
(but not beyond the "booting" system state), using the same macros would
help there too. I had no need for that for my EFI patches.

/
    Leif

[PATCH 0/2] arm: add early_ioremap() support

[Arnd Bergmann]

On Wednesday 26 June 2013, Leif Lindholm wrote:
> On Wed, Jun 26, 2013 at 11:23:50PM +0200, Arnd Bergmann wrote:
> > > Is this an issue here, since (unlike x86) this early_ioremap only works
> > > before paging_init()?
> > 
> > The main problem is that the total fixmap size is only around 900kb,
> > and we want to reserve at least 64kb per cpu for kmap_atomic.
> > If you want to fit multiple 128kb mappings in there, you run out of
> > space really fast.
>  
> Sorry, I still don't get it. Are you saying that kmap_atomic is
> available before kmap_init() (in paging_init())?
> 
> If not, all of my mappings are discarded (well, abandoned to be more
> correct), so I don't see how it affects kmap.

Sorry, I was under the assumption that the mappings are meant to
stay around.

> > > > Extending the iotable mechanism on ARM would be the convenient
> > > > solution for us I think.
> > > 
> > > Could that easily be extended to give similar semantics sufficiently
> > > that we can progress with merging more of the UEFI and ACPI support 
> > > together as common code with x86/ia64?
> > 
> > I don't know what the requirements are, but the idea with iotable
> > is that the mappings stay around at run time, while it seems you want
> > to discard them at some point.
>  
> Indeed - almost immediately.
> 
> x86 early_ioremap can coexist with kmap; the intent of my
> implementation is to use the kmap region only before kmap is available.

So if you never plan to use fixmap and early_ioremap at the same time,
why even bother using the fixmap code? Wouldn't it be easier to just
use the same memory area and ensure we never use fixmap before 
we're done with early_ioremap?

	Arnd

[PATCH 0/2] arm: add early_ioremap() support

[Leif Lindholm]

On Wed, Jun 26, 2013 at 11:23:50PM +0200, Arnd Bergmann wrote:
> > Is this an issue here, since (unlike x86) this early_ioremap only works
> > before paging_init()?
> 
> The main problem is that the total fixmap size is only around 900kb,
> and we want to reserve at least 64kb per cpu for kmap_atomic.
> If you want to fit multiple 128kb mappings in there, you run out of
> space really fast.
 
Sorry, I still don't get it. Are you saying that kmap_atomic is
available before kmap_init() (in paging_init())?

If not, all of my mappings are discarded (well, abandoned to be more
correct), so I don't see how it affects kmap.

> > > Extending the iotable mechanism on ARM would be the convenient
> > > solution for us I think.
> > 
> > Could that easily be extended to give similar semantics sufficiently
> > that we can progress with merging more of the UEFI and ACPI support 
> > together as common code with x86/ia64?
> 
> I don't know what the requirements are, but the idea with iotable
> is that the mappings stay around at run time, while it seems you want
> to discard them at some point.
 
Indeed - almost immediately.

x86 early_ioremap can coexist with kmap; the intent of my
implementation is to use the kmap region only before kmap is available.

/
    Leif

[PATCH 0/2] arm: add early_ioremap() support

[Arnd Bergmann]

On Wednesday 26 June 2013, Leif Lindholm wrote:
> On Wed, Jun 26, 2013 at 08:52:09PM +0200, Arnd Bergmann wrote:
> > I made a similar suggestion to extending the use of fixmap recently, see
> > "Re: SCU registers mapping for CA9/CA5 cores". Russell pointed out that
> > fixmap is intentionally limited to just kmap_atomic uses at the moment
> > and changing that would potentially have a significant impact when we
> > run out of pages in the fixmap area.
>  
> Is this an issue here, since (unlike x86) this early_ioremap only works
> before paging_init()?

The main problem is that the total fixmap size is only around 900kb,
and we want to reserve at least 64kb per cpu for kmap_atomic.
If you want to fit multiple 128kb mappings in there, you run out of
space really fast.


> > Extending the iotable mechanism on ARM would be the convenient
> > solution for us I think.
> 
> Could that easily be extended to give similar semantics sufficiently
> that we can progress with merging more of the UEFI and ACPI support 
> together as common code with x86/ia64?

I don't know what the requirements are, but the idea with iotable
is that the mappings stay around at run time, while it seems you want
to discard them at some point.

	Arnd

[PATCH 0/2] arm: add early_ioremap() support

[Leif Lindholm]

On Wed, Jun 26, 2013 at 08:52:09PM +0200, Arnd Bergmann wrote:
> I made a similar suggestion to extending the use of fixmap recently, see
> "Re: SCU registers mapping for CA9/CA5 cores". Russell pointed out that
> fixmap is intentionally limited to just kmap_atomic uses at the moment
> and changing that would potentially have a significant impact when we
> run out of pages in the fixmap area.
 
Is this an issue here, since (unlike x86) this early_ioremap only works
before paging_init()?

> The method we use on ARM normally is the iotable_init() function, which
> requires hardcoding a virtual address at the moment.
> 
> It might be nicer to change that code than to put early_ioremap into
> fixmap. Note that early_ioremap in fixmap is a bit of a kludge on x86
> as well because it is very much /not/ a fixed mapping like the rest
> of fixmap, they just use it because it's convenient.
 
Yes, but they also only use it (at least the bits where I looked) for
temporary mappings very early in the boot process. That is certainly
how I use it. So at least my intention was to use it before kmap is
even available.

> Extending the iotable mechanism on ARM would be the convenient
> solution for us I think.

Could that easily be extended to give similar semantics sufficiently
that we can progress with merging more of the UEFI and ACPI support 
together as common code with x86/ia64?

/
    Leif

[PATCH 0/2] arm: add early_ioremap() support

[Arnd Bergmann]

On Tuesday 25 June 2013, Leif Lindholm wrote:
> x86 and ia64 have the early_ioremap()/early_iounmap() functions, which are
> useful for supporting things like UEFI, ACPI and SMBIOS, where configuration
> tables need to be parsed before proper memory management is available,
> regardless of highmem status.
> 
> This patchset implements a restricted form of early_ioremap(), available
> before paging_init() only. Like the x86 code on which it is based, it
> (p)re-uses the fixmap regions for its virtual mapping range. Up to 7
> simultaneous mappings of up to 128KB can be accommodated in the available
> fixmap space.

+rmk

I made a similar suggestion to extending the use of fixmap recently, see
"Re: SCU registers mapping for CA9/CA5 cores". Russell pointed out that
fixmap is intentionally limited to just kmap_atomic uses at the moment
and changing that would potentially have a significant impact when we
run out of pages in the fixmap area.

The method we use on ARM normally is the iotable_init() function, which
requires hardcoding a virtual address at the moment.

It might be nicer to change that code than to put early_ioremap into
fixmap. Note that early_ioremap in fixmap is a bit of a kludge on x86
as well because it is very much /not/ a fixed mapping like the rest
of fixmap, they just use it because it's convenient.

Extending the iotable mechanism on ARM would be the convenient
solution for us I think.

	Arnd

[PATCH 0/2] arm: add early_ioremap() support

[Leif Lindholm]

x86 and ia64 have the early_ioremap()/early_iounmap() functions, which are
useful for supporting things like UEFI, ACPI and SMBIOS, where configuration
tables need to be parsed before proper memory management is available,
regardless of highmem status.

This patchset implements a restricted form of early_ioremap(), available
before paging_init() only. Like the x86 code on which it is based, it
(p)re-uses the fixmap regions for its virtual mapping range. Up to 7
simultaneous mappings of up to 128KB can be accommodated in the available
fixmap space.

Leif Lindholm (2):
  Documentation: arm: early_ioremap
  arm: add early_ioremap support

 Documentation/arm/00-INDEX          |    2 +
 Documentation/arm/early_ioremap.txt |   12 ++
 arch/arm/Kconfig                    |    7 +
 arch/arm/include/asm/fixmap.h       |   31 +++-
 arch/arm/include/asm/io.h           |   13 ++
 arch/arm/kernel/setup.c             |    3 +
 arch/arm/mm/Makefile                |    1 +
 arch/arm/mm/early_ioremap.c         |  273 +++++++++++++++++++++++++++++++++++
 arch/arm/mm/mmu.c                   |    2 +
 9 files changed, 342 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/arm/early_ioremap.txt
 create mode 100644 arch/arm/mm/early_ioremap.c

-- 
1.7.10.4