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kasan: clean up KASAN_SHADOW_SCALE_SHIFT usage

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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 <andreyknvl@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2018-02-06 15:36:44 -08:00 committed by Linus Torvalds
parent 5f21f3a8f4
commit 917538e212
5 changed files with 22 additions and 15 deletions
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17
arch/arm64/include/asm/kasan.h
View File

@ -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);

3
arch/arm64/include/asm/memory.h
View File

@ -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)

3
arch/arm64/mm/kasan_init.c
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@ -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,

12
arch/x86/include/asm/kasan.h
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@ -4,6 +4,7 @@
#include <linux/const.h>
#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__

2
include/linux/kasan.h
View File

@ -11,8 +11,6 @@ struct task_struct;
#ifdef CONFIG_KASAN
#define KASAN_SHADOW_SCALE_SHIFT 3
#include <asm/kasan.h>
#include <asm/pgtable.h>