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[PATCH v5 0/6] KASAN for amr64

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  [PATCH v5 0/6]  KASAN for amr64 Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-11 00:30 +0200
    [PATCH v5 4/6] arm64: move PGD_SIZE definition to pgalloc.h Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-11 00:30 +0200
    [PATCH v5 6/6] ARM64: kasan: print memory assignment Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-11 00:30 +0200
    [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow() Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-11 00:30 +0200
      Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic  kasan_populate_zero_shadow() Catalin Marinas <catalin.marinas@arm.com> - 2015-08-11 17:50 +0200
        Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic  kasan_populate_zero_shadow() Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-11 18:30 +0200
          Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic  kasan_populate_zero_shadow() Catalin Marinas <catalin.marinas@arm.com> - 2015-08-11 18:50 +0200
            Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic  kasan_populate_zero_shadow() Will Deacon <will.deacon@arm.com> - 2015-08-12 11:40 +0200
              Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow() Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-12 14:20 +0200
                Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic  kasan_populate_zero_shadow() Will Deacon <will.deacon@arm.com> - 2015-08-12 15:50 +0200
            Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow() Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-12 11:40 +0200
        Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic  kasan_populate_zero_shadow() Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-11 18:40 +0200

#1204608 — [PATCH v5 0/6] KASAN for amr64

For git users patches are available in git:
        git://github.com/aryabinin/linux.git kasan/arm64v5

Changes since v4:
 - Generate KASAN_SHADOW_OFFSET using 32 bit arithmetic
 - merge patches x86/kasan: switch to generic kasan_populate_zero_shadow()
    and mm: introduce generic kasan_populate_zero_shadow() into one.
 - remove useless check for start != 0 in clear_pgds()
 - Don't generate KASAN_SHADOW_OFFSET in Makefile for x86,
   assign it in Makefile.kasan if CONFIG_KASAN_SHADOW_OFFSET was defined.
 
Changes since v3:
 - Generate KASAN_SHADOW_OFFSET in Makefile
 - zero_p*_populate() functions now return void
 - Switch x86 to generic kasan_populate_zero_shadow() too
 - Add license headers
 - fix memleak in kasan_populate_zero_shadow:
       Following code could leak memory when pgd_populate() is nop:
                void *p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
                pgd_populate(&init_mm, pgd, p);
        This was replaced by:
                 pgd_populate(&init_mm, pgd, early_alloc(PAGE_SIZE, NUMA_NO_NODE));

Changes since v2:
 - Rebase on top of v4.2-rc3
 - Address feedback from Catalin.
 - Print memory assignment from Linus
 - Add message about KASAN being initialized

Changes since v1:
 - Address feedback from Catalin.
 - Generalize some kasan init code from arch/x86/mm/kasan_init_64.c
    and reuse it for arm64.
 - Some bugfixes, including:
        add missing arm64/include/asm/kasan.h
        add tlb flush after changing ttbr1
 - Add code comments.

Andrey Ryabinin (5):
  x86/kasan: define KASAN_SHADOW_OFFSET per architecture
  x86/kasan, mm: introduce generic kasan_populate_zero_shadow()
  arm64: introduce VA_START macro - the first kernel virtual address.
  arm64: move PGD_SIZE definition to pgalloc.h
  arm64: add KASAN support

Linus Walleij (1):
  ARM64: kasan: print memory assignment

 arch/arm64/Kconfig               |   1 +
 arch/arm64/Makefile              |   7 ++
 arch/arm64/include/asm/kasan.h   |  36 +++++++++
 arch/arm64/include/asm/memory.h  |   2 +
 arch/arm64/include/asm/pgalloc.h |   1 +
 arch/arm64/include/asm/pgtable.h |   9 ++-
 arch/arm64/include/asm/string.h  |  16 ++++
 arch/arm64/kernel/arm64ksyms.c   |   3 +
 arch/arm64/kernel/head.S         |   3 +
 arch/arm64/kernel/module.c       |  16 +++-
 arch/arm64/kernel/setup.c        |   2 +
 arch/arm64/lib/memcpy.S          |   3 +
 arch/arm64/lib/memmove.S         |   7 +-
 arch/arm64/lib/memset.S          |   3 +
 arch/arm64/mm/Makefile           |   3 +
 arch/arm64/mm/init.c             |   6 ++
 arch/arm64/mm/kasan_init.c       | 165 +++++++++++++++++++++++++++++++++++++++
 arch/arm64/mm/pgd.c              |   2 -
 arch/x86/include/asm/kasan.h     |   3 +
 arch/x86/mm/kasan_init_64.c      | 123 ++---------------------------
 include/linux/kasan.h            |  10 ++-
 mm/kasan/Makefile                |   2 +-
 mm/kasan/kasan_init.c            | 152 ++++++++++++++++++++++++++++++++++++
 scripts/Makefile.kasan           |   4 +-
 24 files changed, 450 insertions(+), 129 deletions(-)
 create mode 100644 arch/arm64/include/asm/kasan.h
 create mode 100644 arch/arm64/mm/kasan_init.c
 create mode 100644 mm/kasan/kasan_init.c

-- 
2.4.6

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#1204610 — [PATCH v5 4/6] arm64: move PGD_SIZE definition to pgalloc.h

This will be used by KASAN latter.

Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/pgalloc.h | 1 +
 arch/arm64/mm/pgd.c              | 2 --
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 7642056..c150539 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -27,6 +27,7 @@
 #define check_pgt_cache()		do { } while (0)
 
 #define PGALLOC_GFP	(GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO)
+#define PGD_SIZE	(PTRS_PER_PGD * sizeof(pgd_t))
 
 #if CONFIG_PGTABLE_LEVELS > 2
 
diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c
index 71ca104..cb3ba1b 100644
--- a/arch/arm64/mm/pgd.c
+++ b/arch/arm64/mm/pgd.c
@@ -28,8 +28,6 @@
 
 #include "mm.h"
 
-#define PGD_SIZE	(PTRS_PER_PGD * sizeof(pgd_t))
-
 static struct kmem_cache *pgd_cache;
 
 pgd_t *pgd_alloc(struct mm_struct *mm)
-- 
2.4.6

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#1204611 — [PATCH v5 6/6] ARM64: kasan: print memory assignment

From: Linus Walleij <linus.walleij@linaro.org>

This prints out the virtual memory assigned to KASan in the
boot crawl along with other memory assignments, if and only
if KASan is activated.

Example dmesg from the Juno Development board:

Memory: 1691156K/2080768K available (5465K kernel code, 444K rwdata,
2160K rodata, 340K init, 217K bss, 373228K reserved, 16384K cma-reserved)
Virtual kernel memory layout:
    kasan   : 0xffffff8000000000 - 0xffffff9000000000   (    64 GB)
    vmalloc : 0xffffff9000000000 - 0xffffffbdbfff0000   (   182 GB)
    vmemmap : 0xffffffbdc0000000 - 0xffffffbfc0000000   (     8 GB maximum)
              0xffffffbdc2000000 - 0xffffffbdc3fc0000   (    31 MB actual)
    fixed   : 0xffffffbffabfd000 - 0xffffffbffac00000   (    12 KB)
    PCI I/O : 0xffffffbffae00000 - 0xffffffbffbe00000   (    16 MB)
    modules : 0xffffffbffc000000 - 0xffffffc000000000   (    64 MB)
    memory  : 0xffffffc000000000 - 0xffffffc07f000000   (  2032 MB)
      .init : 0xffffffc0007f5000 - 0xffffffc00084a000   (   340 KB)
      .text : 0xffffffc000080000 - 0xffffffc0007f45b4   (  7634 KB)
      .data : 0xffffffc000850000 - 0xffffffc0008bf200   (   445 KB)

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/mm/init.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index ad87ce8..3930692 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -298,6 +298,9 @@ void __init mem_init(void)
 #define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
 
 	pr_notice("Virtual kernel memory layout:\n"
+#ifdef CONFIG_KASAN
+		  "    kasan   : 0x%16lx - 0x%16lx   (%6ld GB)\n"
+#endif
 		  "    vmalloc : 0x%16lx - 0x%16lx   (%6ld GB)\n"
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 		  "    vmemmap : 0x%16lx - 0x%16lx   (%6ld GB maximum)\n"
@@ -310,6 +313,9 @@ void __init mem_init(void)
 		  "      .init : 0x%p" " - 0x%p" "   (%6ld KB)\n"
 		  "      .text : 0x%p" " - 0x%p" "   (%6ld KB)\n"
 		  "      .data : 0x%p" " - 0x%p" "   (%6ld KB)\n",
+#ifdef CONFIG_KASAN
+		  MLG(KASAN_SHADOW_START, KASAN_SHADOW_END),
+#endif
 		  MLG(VMALLOC_START, VMALLOC_END),
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 		  MLG((unsigned long)vmemmap,
-- 
2.4.6

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#1204613 — [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

Introduce generic kasan_populate_zero_shadow(shadow_start, shadow_end).
This function maps kasan_zero_page to the [shadow_start, shadow_end]
addresses.

This replaces x86_64 specific populate_zero_shadow() and will
be used for ARM64 in follow on patches.

Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
---
 arch/x86/mm/kasan_init_64.c | 123 ++---------------------------------
 include/linux/kasan.h       |   9 +++
 mm/kasan/Makefile           |   2 +-
 mm/kasan/kasan_init.c       | 152 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 167 insertions(+), 119 deletions(-)
 create mode 100644 mm/kasan/kasan_init.c

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index e1840f3..9ce5da2 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -12,20 +12,6 @@
 extern pgd_t early_level4_pgt[PTRS_PER_PGD];
 extern struct range pfn_mapped[E820_X_MAX];
 
-static pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
-static pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
-static pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
-
-/*
- * This page used as early shadow. We don't use empty_zero_page
- * at early stages, stack instrumentation could write some garbage
- * to this page.
- * Latter we reuse it as zero shadow for large ranges of memory
- * that allowed to access, but not instrumented by kasan
- * (vmalloc/vmemmap ...).
- */
-static unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
-
 static int __init map_range(struct range *range)
 {
 	unsigned long start;
@@ -62,106 +48,6 @@ static void __init kasan_map_early_shadow(pgd_t *pgd)
 	}
 }
 
-static int __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
-				unsigned long end)
-{
-	pte_t *pte = pte_offset_kernel(pmd, addr);
-
-	while (addr + PAGE_SIZE <= end) {
-		WARN_ON(!pte_none(*pte));
-		set_pte(pte, __pte(__pa_nodebug(kasan_zero_page)
-					| __PAGE_KERNEL_RO));
-		addr += PAGE_SIZE;
-		pte = pte_offset_kernel(pmd, addr);
-	}
-	return 0;
-}
-
-static int __init zero_pmd_populate(pud_t *pud, unsigned long addr,
-				unsigned long end)
-{
-	int ret = 0;
-	pmd_t *pmd = pmd_offset(pud, addr);
-
-	while (IS_ALIGNED(addr, PMD_SIZE) && addr + PMD_SIZE <= end) {
-		WARN_ON(!pmd_none(*pmd));
-		set_pmd(pmd, __pmd(__pa_nodebug(kasan_zero_pte)
-					| _KERNPG_TABLE));
-		addr += PMD_SIZE;
-		pmd = pmd_offset(pud, addr);
-	}
-	if (addr < end) {
-		if (pmd_none(*pmd)) {
-			void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
-			if (!p)
-				return -ENOMEM;
-			set_pmd(pmd, __pmd(__pa_nodebug(p) | _KERNPG_TABLE));
-		}
-		ret = zero_pte_populate(pmd, addr, end);
-	}
-	return ret;
-}
-
-
-static int __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
-				unsigned long end)
-{
-	int ret = 0;
-	pud_t *pud = pud_offset(pgd, addr);
-
-	while (IS_ALIGNED(addr, PUD_SIZE) && addr + PUD_SIZE <= end) {
-		WARN_ON(!pud_none(*pud));
-		set_pud(pud, __pud(__pa_nodebug(kasan_zero_pmd)
-					| _KERNPG_TABLE));
-		addr += PUD_SIZE;
-		pud = pud_offset(pgd, addr);
-	}
-
-	if (addr < end) {
-		if (pud_none(*pud)) {
-			void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
-			if (!p)
-				return -ENOMEM;
-			set_pud(pud, __pud(__pa_nodebug(p) | _KERNPG_TABLE));
-		}
-		ret = zero_pmd_populate(pud, addr, end);
-	}
-	return ret;
-}
-
-static int __init zero_pgd_populate(unsigned long addr, unsigned long end)
-{
-	int ret = 0;
-	pgd_t *pgd = pgd_offset_k(addr);
-
-	while (IS_ALIGNED(addr, PGDIR_SIZE) && addr + PGDIR_SIZE <= end) {
-		WARN_ON(!pgd_none(*pgd));
-		set_pgd(pgd, __pgd(__pa_nodebug(kasan_zero_pud)
-					| _KERNPG_TABLE));
-		addr += PGDIR_SIZE;
-		pgd = pgd_offset_k(addr);
-	}
-
-	if (addr < end) {
-		if (pgd_none(*pgd)) {
-			void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
-			if (!p)
-				return -ENOMEM;
-			set_pgd(pgd, __pgd(__pa_nodebug(p) | _KERNPG_TABLE));
-		}
-		ret = zero_pud_populate(pgd, addr, end);
-	}
-	return ret;
-}
-
-
-static void __init populate_zero_shadow(const void *start, const void *end)
-{
-	if (zero_pgd_populate((unsigned long)start, (unsigned long)end))
-		panic("kasan: unable to map zero shadow!");
-}
-
-
 #ifdef CONFIG_KASAN_INLINE
 static int kasan_die_handler(struct notifier_block *self,
 			     unsigned long val,
@@ -213,7 +99,7 @@ void __init kasan_init(void)
 
 	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 
-	populate_zero_shadow((void *)KASAN_SHADOW_START,
+	kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
 			kasan_mem_to_shadow((void *)PAGE_OFFSET));
 
 	for (i = 0; i < E820_X_MAX; i++) {
@@ -223,14 +109,15 @@ void __init kasan_init(void)
 		if (map_range(&pfn_mapped[i]))
 			panic("kasan: unable to allocate shadow!");
 	}
-	populate_zero_shadow(kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
-			kasan_mem_to_shadow((void *)__START_KERNEL_map));
+	kasan_populate_zero_shadow(
+		kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
+		kasan_mem_to_shadow((void *)__START_KERNEL_map));
 
 	vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
 			(unsigned long)kasan_mem_to_shadow(_end),
 			NUMA_NO_NODE);
 
-	populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
+	kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 			(void *)KASAN_SHADOW_END);
 
 	memset(kasan_zero_page, 0, PAGE_SIZE);
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 6fb1c7d..4b9f85c 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -12,8 +12,17 @@ struct vm_struct;
 #define KASAN_SHADOW_SCALE_SHIFT 3
 
 #include <asm/kasan.h>
+#include <asm/pgtable.h>
 #include <linux/sched.h>
 
+extern unsigned char kasan_zero_page[PAGE_SIZE];
+extern pte_t kasan_zero_pte[PTRS_PER_PTE];
+extern pmd_t kasan_zero_pmd[PTRS_PER_PMD];
+extern pud_t kasan_zero_pud[PTRS_PER_PUD];
+
+void kasan_populate_zero_shadow(const void *shadow_start,
+				const void *shadow_end);
+
 static inline void *kasan_mem_to_shadow(const void *addr)
 {
 	return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index bd837b8..6471014 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -5,4 +5,4 @@ CFLAGS_REMOVE_kasan.o = -pg
 # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
 CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 
-obj-y := kasan.o report.o
+obj-y := kasan.o report.o kasan_init.o
diff --git a/mm/kasan/kasan_init.c b/mm/kasan/kasan_init.c
new file mode 100644
index 0000000..3f9a41c
--- /dev/null
+++ b/mm/kasan/kasan_init.c
@@ -0,0 +1,152 @@
+/*
+ * This file contains some kasan initialization code.
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bootmem.h>
+#include <linux/init.h>
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/pfn.h>
+
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+
+/*
+ * This page serves two purposes:
+ *   - It used as early shadow memory. The entire shadow region populated
+ *     with this page, before we will be able to setup normal shadow memory.
+ *   - Latter it reused it as zero shadow to cover large ranges of memory
+ *     that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
+ */
+unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
+
+#if CONFIG_PGTABLE_LEVELS > 3
+pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
+#endif
+#if CONFIG_PGTABLE_LEVELS > 2
+pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
+#endif
+pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
+
+static __init void *early_alloc(size_t size, int node)
+{
+	return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
+					BOOTMEM_ALLOC_ACCESSIBLE, node);
+}
+
+static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
+				unsigned long end)
+{
+	pte_t *pte = pte_offset_kernel(pmd, addr);
+	pte_t zero_pte;
+
+	zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
+	zero_pte = pte_wrprotect(zero_pte);
+
+	while (addr + PAGE_SIZE <= end) {
+		set_pte_at(&init_mm, addr, pte, zero_pte);
+		addr += PAGE_SIZE;
+		pte = pte_offset_kernel(pmd, addr);
+	}
+}
+
+static void __init zero_pmd_populate(pud_t *pud, unsigned long addr,
+				unsigned long end)
+{
+	pmd_t *pmd = pmd_offset(pud, addr);
+	unsigned long next;
+
+	do {
+		next = pmd_addr_end(addr, end);
+
+		if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
+			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+			continue;
+		}
+
+		if (pmd_none(*pmd)) {
+			pmd_populate_kernel(&init_mm, pmd,
+					early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+		}
+		zero_pte_populate(pmd, addr, next);
+	} while (pmd++, addr = next, addr != end);
+}
+
+static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
+				unsigned long end)
+{
+	pud_t *pud = pud_offset(pgd, addr);
+	unsigned long next;
+
+	do {
+		next = pud_addr_end(addr, end);
+		if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
+			pmd_t *pmd;
+
+			pud_populate(&init_mm, pud, kasan_zero_pmd);
+			pmd = pmd_offset(pud, addr);
+			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+			continue;
+		}
+
+		if (pud_none(*pud)) {
+			pud_populate(&init_mm, pud,
+				early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+		}
+		zero_pmd_populate(pud, addr, next);
+	} while (pud++, addr = next, addr != end);
+}
+
+/**
+ * kasan_populate_zero_shadow - populate shadow memory region with
+ *                               kasan_zero_page
+ * @shadow_start - start of the memory range to populate
+ * @shadow_end   - end of the memory range to populate
+ */
+void __init kasan_populate_zero_shadow(const void *shadow_start,
+				const void *shadow_end)
+{
+	unsigned long addr = (unsigned long)shadow_start;
+	unsigned long end = (unsigned long)shadow_end;
+	pgd_t *pgd = pgd_offset_k(addr);
+	unsigned long next;
+
+	do {
+		next = pgd_addr_end(addr, end);
+
+		if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
+			pud_t *pud;
+			pmd_t *pmd;
+
+			/*
+			 * kasan_zero_pud should be populated with pmds
+			 * at this moment.
+			 * [pud,pmd]_populate*() below needed only for
+			 * 3,2 - level page tables where we don't have
+			 * puds,pmds, so pgd_populate(), pud_populate()
+			 * is noops.
+			 */
+			pgd_populate(&init_mm, pgd, kasan_zero_pud);
+			pud = pud_offset(pgd, addr);
+			pud_populate(&init_mm, pud, kasan_zero_pmd);
+			pmd = pmd_offset(pud, addr);
+			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+			continue;
+		}
+
+		if (pgd_none(*pgd)) {
+			pgd_populate(&init_mm, pgd,
+				early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+		}
+		zero_pud_populate(pgd, addr, next);
+	} while (pgd++, addr = next, addr != end);
+}
-- 
2.4.6

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#1205224 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

On Tue, Aug 11, 2015 at 05:18:15AM +0300, Andrey Ryabinin wrote:
> --- /dev/null
> +++ b/mm/kasan/kasan_init.c
[...]
> +#if CONFIG_PGTABLE_LEVELS > 3
> +pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
> +#endif
> +#if CONFIG_PGTABLE_LEVELS > 2
> +pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
> +#endif
> +pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;

Is there any problem if you don't add the #ifs here? Wouldn't the linker
remove them if they are not used?

Original hunk copied here for easy comparison:

> -static int __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
> -				unsigned long end)
> -{
> -	pte_t *pte = pte_offset_kernel(pmd, addr);
> -
> -	while (addr + PAGE_SIZE <= end) {
> -		WARN_ON(!pte_none(*pte));
> -		set_pte(pte, __pte(__pa_nodebug(kasan_zero_page)
> -					| __PAGE_KERNEL_RO));
> -		addr += PAGE_SIZE;
> -		pte = pte_offset_kernel(pmd, addr);
> -	}
> -	return 0;
> -}
[...]
> +static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
> +				unsigned long end)
> +{
> +	pte_t *pte = pte_offset_kernel(pmd, addr);
> +	pte_t zero_pte;
> +
> +	zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
> +	zero_pte = pte_wrprotect(zero_pte);
> +
> +	while (addr + PAGE_SIZE <= end) {
> +		set_pte_at(&init_mm, addr, pte, zero_pte);
> +		addr += PAGE_SIZE;
> +		pte = pte_offset_kernel(pmd, addr);
> +	}
> +}

I think there are some differences with the original x86 code. The first
one is the use of __pa_nodebug, does it cause any problems if
CONFIG_DEBUG_VIRTUAL is enabled?

The second is the use of a read-only attribute when mapping
kasan_zero_page on x86. Can it cope with a writable mapping?

If there are no issues, it should be documented in the commit log.

-- 
Catalin
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#1205261 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

On 08/11/2015 06:41 PM, Catalin Marinas wrote:
> On Tue, Aug 11, 2015 at 05:18:15AM +0300, Andrey Ryabinin wrote:
>> --- /dev/null
>> +++ b/mm/kasan/kasan_init.c
> [...]
>> +#if CONFIG_PGTABLE_LEVELS > 3
>> +pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
>> +#endif
>> +#if CONFIG_PGTABLE_LEVELS > 2
>> +pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> +#endif
>> +pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
> 
> Is there any problem if you don't add the #ifs here? Wouldn't the linker
> remove them if they are not used?
> 


> Original hunk copied here for easy comparison:
> 
>> -static int __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
>> -				unsigned long end)
>> -{
>> -	pte_t *pte = pte_offset_kernel(pmd, addr);
>> -
>> -	while (addr + PAGE_SIZE <= end) {
>> -		WARN_ON(!pte_none(*pte));
>> -		set_pte(pte, __pte(__pa_nodebug(kasan_zero_page)
>> -					| __PAGE_KERNEL_RO));
>> -		addr += PAGE_SIZE;
>> -		pte = pte_offset_kernel(pmd, addr);
>> -	}
>> -	return 0;
>> -}
> [...]
>> +static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
>> +				unsigned long end)
>> +{
>> +	pte_t *pte = pte_offset_kernel(pmd, addr);
>> +	pte_t zero_pte;
>> +
>> +	zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
>> +	zero_pte = pte_wrprotect(zero_pte);
>> +
>> +	while (addr + PAGE_SIZE <= end) {
>> +		set_pte_at(&init_mm, addr, pte, zero_pte);
>> +		addr += PAGE_SIZE;
>> +		pte = pte_offset_kernel(pmd, addr);
>> +	}
>> +}
> 
> I think there are some differences with the original x86 code. The first
> one is the use of __pa_nodebug, does it cause any problems if
> CONFIG_DEBUG_VIRTUAL is enabled?
> 
__pa_nodebug() should be used before kasan_early_init(), this piece of code
executed far later, so it's ok to use __pa() here.
This was actually a mistake in original code to use __pa_nodebug().

> The second is the use of a read-only attribute when mapping
> kasan_zero_page on x86. Can it cope with a writable mapping?
> 

Did you miss this line:

+	zero_pte = pte_wrprotect(zero_pte);

?


> If there are no issues, it should be documented in the commit log.
> 
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#1205272 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

On Tue, Aug 11, 2015 at 07:25:12PM +0300, Andrey Ryabinin wrote:
> On 08/11/2015 06:41 PM, Catalin Marinas wrote:
> > On Tue, Aug 11, 2015 at 05:18:15AM +0300, Andrey Ryabinin wrote:
> >> --- /dev/null
> >> +++ b/mm/kasan/kasan_init.c
> > [...]
> >> +#if CONFIG_PGTABLE_LEVELS > 3
> >> +pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
> >> +#endif
> >> +#if CONFIG_PGTABLE_LEVELS > 2
> >> +pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
> >> +#endif
> >> +pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
> > 
> > Is there any problem if you don't add the #ifs here? Wouldn't the linker
> > remove them if they are not used?
> 
> > Original hunk copied here for easy comparison:
> > 
> >> -static int __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
> >> -				unsigned long end)
> >> -{
> >> -	pte_t *pte = pte_offset_kernel(pmd, addr);
> >> -
> >> -	while (addr + PAGE_SIZE <= end) {
> >> -		WARN_ON(!pte_none(*pte));
> >> -		set_pte(pte, __pte(__pa_nodebug(kasan_zero_page)
> >> -					| __PAGE_KERNEL_RO));
> >> -		addr += PAGE_SIZE;
> >> -		pte = pte_offset_kernel(pmd, addr);
> >> -	}
> >> -	return 0;
> >> -}
> > [...]
> >> +static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
> >> +				unsigned long end)
> >> +{
> >> +	pte_t *pte = pte_offset_kernel(pmd, addr);
> >> +	pte_t zero_pte;
> >> +
> >> +	zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
> >> +	zero_pte = pte_wrprotect(zero_pte);
> >> +
> >> +	while (addr + PAGE_SIZE <= end) {
> >> +		set_pte_at(&init_mm, addr, pte, zero_pte);
> >> +		addr += PAGE_SIZE;
> >> +		pte = pte_offset_kernel(pmd, addr);
> >> +	}
> >> +}
> > 
> > I think there are some differences with the original x86 code. The first
> > one is the use of __pa_nodebug, does it cause any problems if
> > CONFIG_DEBUG_VIRTUAL is enabled?
> 
> __pa_nodebug() should be used before kasan_early_init(), this piece of code
> executed far later, so it's ok to use __pa() here.
> This was actually a mistake in original code to use __pa_nodebug().

OK. So please add a comment in the commit log.

> > The second is the use of a read-only attribute when mapping
> > kasan_zero_page on x86. Can it cope with a writable mapping?
> > 
> 
> Did you miss this line:
> 
> +	zero_pte = pte_wrprotect(zero_pte);

Ah, yes, I missed this.

Anyway, for this patch:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Not sure how you plan to merge it though since there are x86
dependencies. I could send the whole series via tip or the mm tree (and
I guess it's pretty late for 4.3).
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#1205826 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

On Wed, Aug 12, 2015 at 10:30:37AM +0100, Andrey Ryabinin wrote:
> 2015-08-11 19:40 GMT+03:00 Catalin Marinas <catalin.marinas@arm.com>:
> >
> > Not sure how you plan to merge it though since there are x86
> > dependencies. I could send the whole series via tip or the mm tree (and
> > I guess it's pretty late for 4.3).
> 
> Via mm tree, I guess.
> If this is too late for 4.3, then I'll update changelog and send v6
> after 4.3-rc1 release.

That's probably the best bet, as I suspect we'll get some non-trivial
conflicts with the arm64 tree at this stage.

Will
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#1206000 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

2015-08-12 12:37 GMT+03:00 Will Deacon <will.deacon@arm.com>:
> On Wed, Aug 12, 2015 at 10:30:37AM +0100, Andrey Ryabinin wrote:
>> 2015-08-11 19:40 GMT+03:00 Catalin Marinas <catalin.marinas@arm.com>:
>> >
>> > Not sure how you plan to merge it though since there are x86
>> > dependencies. I could send the whole series via tip or the mm tree (and
>> > I guess it's pretty late for 4.3).
>>
>> Via mm tree, I guess.
>> If this is too late for 4.3, then I'll update changelog and send v6
>> after 4.3-rc1 release.
>
> That's probably the best bet, as I suspect we'll get some non-trivial
> conflicts with the arm64 tree at this stage.
>
> Will

Or, if x86 maintainers are agree to take first 2 patches in 4.3,
the rest of the series could go into arm64 tree later.
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#1206103 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

On Wed, Aug 12, 2015 at 01:19:03PM +0100, Andrey Ryabinin wrote:
> 2015-08-12 12:37 GMT+03:00 Will Deacon <will.deacon@arm.com>:
> > On Wed, Aug 12, 2015 at 10:30:37AM +0100, Andrey Ryabinin wrote:
> >> 2015-08-11 19:40 GMT+03:00 Catalin Marinas <catalin.marinas@arm.com>:
> >> >
> >> > Not sure how you plan to merge it though since there are x86
> >> > dependencies. I could send the whole series via tip or the mm tree (and
> >> > I guess it's pretty late for 4.3).
> >>
> >> Via mm tree, I guess.
> >> If this is too late for 4.3, then I'll update changelog and send v6
> >> after 4.3-rc1 release.
> >
> > That's probably the best bet, as I suspect we'll get some non-trivial
> > conflicts with the arm64 tree at this stage.
> >
> Or, if x86 maintainers are agree to take first 2 patches in 4.3,
> the rest of the series could go into arm64 tree later.

Yup, that would be even better for us!

Will
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#1205837 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

2015-08-11 19:40 GMT+03:00 Catalin Marinas <catalin.marinas@arm.com>:
>
> Not sure how you plan to merge it though since there are x86
> dependencies. I could send the whole series via tip or the mm tree (and
> I guess it's pretty late for 4.3).

Via mm tree, I guess.
If this is too late for 4.3, then I'll update changelog and send v6
after 4.3-rc1 release.
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#1205266 — Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()

On 08/11/2015 06:41 PM, Catalin Marinas wrote:
> On Tue, Aug 11, 2015 at 05:18:15AM +0300, Andrey Ryabinin wrote:
>> --- /dev/null
>> +++ b/mm/kasan/kasan_init.c
> [...]
>> +#if CONFIG_PGTABLE_LEVELS > 3
>> +pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
>> +#endif
>> +#if CONFIG_PGTABLE_LEVELS > 2
>> +pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> +#endif
>> +pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
> 
> Is there any problem if you don't add the #ifs here? Wouldn't the linker
> remove them if they are not used?
> 

AFAIK such optimization is possible if we build with -fdata-sections flag and
use --gc-sections flag in linker, but we don't do this.
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