Commit 917538e2 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Linus Torvalds
Browse files

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: default avatarAndrey Konovalov <andreyknvl@google.com>
Acked-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5f21f3a8

arch/arm64/include/asm/kasan.h

+10 −7
Original line number Diff line number Diff line
@@ -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);

arch/arm64/include/asm/memory.h

+2 −1
Original line number Diff line number Diff line
@@ -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)

arch/arm64/mm/kasan_init.c

+2 −1
Original line number Diff line number Diff line
@@ -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,

arch/x86/include/asm/kasan.h

+8 −4
Original line number Diff line number Diff line
@@ -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__

include/linux/kasan.h

+0 −2
Original line number Diff line number Diff line
@@ -11,8 +11,6 @@ struct task_struct; 


#ifdef CONFIG_KASAN



#define KASAN_SHADOW_SCALE_SHIFT 3



#include <asm/kasan.h>

#include <asm/pgtable.h>

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