From 917538e212a2c080af95ccb4376c5387fac08176 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Tue, 6 Feb 2018 15:36:44 -0800 Subject: [PATCH] kasan: clean up KASAN_SHADOW_SCALE_SHIFT usage Right now the fact that KASAN uses a single shadow byte for 8 bytes of memory is scattered all over the code. This change defines KASAN_SHADOW_SCALE_SHIFT early in asm include files and makes use of this constant where necessary. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/34937ca3b90736eaad91b568edf5684091f662e3.1515775666.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Acked-by: Andrey Ryabinin Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arm64/include/asm/kasan.h | 17 ++++++++++------- arch/arm64/include/asm/memory.h | 3 ++- arch/arm64/mm/kasan_init.c | 3 ++- arch/x86/include/asm/kasan.h | 12 ++++++++---- include/linux/kasan.h | 2 -- 5 files changed, 22 insertions(+), 15 deletions(-) diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h index e266f80e45b7..8758bb008436 100644 --- a/arch/arm64/include/asm/kasan.h +++ b/arch/arm64/include/asm/kasan.h @@ -12,7 +12,8 @@ /* * KASAN_SHADOW_START: beginning of the kernel virtual addresses. - * KASAN_SHADOW_END: KASAN_SHADOW_START + 1/8 of kernel virtual addresses. + * KASAN_SHADOW_END: KASAN_SHADOW_START + 1/N of kernel virtual addresses, + * where N = (1 << KASAN_SHADOW_SCALE_SHIFT). */ #define KASAN_SHADOW_START (VA_START) #define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE) @@ -20,14 +21,16 @@ /* * This value is used to map an address to the corresponding shadow * address by the following formula: - * shadow_addr = (address >> 3) + KASAN_SHADOW_OFFSET; + * shadow_addr = (address >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET * - * (1 << 61) shadow addresses - [KASAN_SHADOW_OFFSET,KASAN_SHADOW_END] - * cover all 64-bits of virtual addresses. So KASAN_SHADOW_OFFSET - * should satisfy the following equation: - * KASAN_SHADOW_OFFSET = KASAN_SHADOW_END - (1ULL << 61) + * (1 << (64 - KASAN_SHADOW_SCALE_SHIFT)) shadow addresses that lie in range + * [KASAN_SHADOW_OFFSET, KASAN_SHADOW_END) cover all 64-bits of virtual + * addresses. So KASAN_SHADOW_OFFSET should satisfy the following equation: + * KASAN_SHADOW_OFFSET = KASAN_SHADOW_END - + * (1ULL << (64 - KASAN_SHADOW_SCALE_SHIFT)) */ -#define KASAN_SHADOW_OFFSET (KASAN_SHADOW_END - (1ULL << (64 - 3))) +#define KASAN_SHADOW_OFFSET (KASAN_SHADOW_END - (1ULL << \ + (64 - KASAN_SHADOW_SCALE_SHIFT))) void kasan_init(void); void kasan_copy_shadow(pgd_t *pgdir); diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index d4bae7d6e0d8..50fa96a49792 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -85,7 +85,8 @@ * stack size when KASAN is in use. */ #ifdef CONFIG_KASAN -#define KASAN_SHADOW_SIZE (UL(1) << (VA_BITS - 3)) +#define KASAN_SHADOW_SCALE_SHIFT 3 +#define KASAN_SHADOW_SIZE (UL(1) << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT)) #define KASAN_THREAD_SHIFT 1 #else #define KASAN_SHADOW_SIZE (0) diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index acba49fb5aac..6e02e6fb4c7b 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -135,7 +135,8 @@ static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, /* The early shadow maps everything to a single page of zeroes */ asmlinkage void __init kasan_early_init(void) { - BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_END - (1UL << 61)); + BUILD_BUG_ON(KASAN_SHADOW_OFFSET != + KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, diff --git a/arch/x86/include/asm/kasan.h b/arch/x86/include/asm/kasan.h index b577dd0916aa..13e70da38bed 100644 --- a/arch/x86/include/asm/kasan.h +++ b/arch/x86/include/asm/kasan.h @@ -4,6 +4,7 @@ #include #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) +#define KASAN_SHADOW_SCALE_SHIFT 3 /* * Compiler uses shadow offset assuming that addresses start @@ -12,12 +13,15 @@ * 'kernel address space start' >> KASAN_SHADOW_SCALE_SHIFT */ #define KASAN_SHADOW_START (KASAN_SHADOW_OFFSET + \ - ((-1UL << __VIRTUAL_MASK_SHIFT) >> 3)) + ((-1UL << __VIRTUAL_MASK_SHIFT) >> \ + KASAN_SHADOW_SCALE_SHIFT)) /* - * 47 bits for kernel address -> (47 - 3) bits for shadow - * 56 bits for kernel address -> (56 - 3) bits for shadow + * 47 bits for kernel address -> (47 - KASAN_SHADOW_SCALE_SHIFT) bits for shadow + * 56 bits for kernel address -> (56 - KASAN_SHADOW_SCALE_SHIFT) bits for shadow */ -#define KASAN_SHADOW_END (KASAN_SHADOW_START + (1ULL << (__VIRTUAL_MASK_SHIFT - 3))) +#define KASAN_SHADOW_END (KASAN_SHADOW_START + \ + (1ULL << (__VIRTUAL_MASK_SHIFT - \ + KASAN_SHADOW_SCALE_SHIFT))) #ifndef __ASSEMBLY__ diff --git a/include/linux/kasan.h b/include/linux/kasan.h index fc45f8952d1e..adc13474a53b 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -11,8 +11,6 @@ struct task_struct; #ifdef CONFIG_KASAN -#define KASAN_SHADOW_SCALE_SHIFT 3 - #include #include