Commit 7f1e541f authored by Andrey Ryabinin's avatar Andrey Ryabinin Committed by Linus Torvalds

compiler.h: Add read_word_at_a_time() function.

Sometimes we know that it's safe to do potentially out-of-bounds access
because we know it won't cross a page boundary.  Still, KASAN will
report this as a bug.

Add read_word_at_a_time() function which is supposed to be used in such
cases.  In read_word_at_a_time() KASAN performs relaxed check - only the
first byte of access is validated.
Signed-off-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bdb5ac80
...@@ -238,6 +238,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s ...@@ -238,6 +238,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
* required ordering. * required ordering.
*/ */
#include <asm/barrier.h> #include <asm/barrier.h>
#include <linux/kasan-checks.h>
#define __READ_ONCE(x, check) \ #define __READ_ONCE(x, check) \
({ \ ({ \
...@@ -257,6 +258,13 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s ...@@ -257,6 +258,13 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
*/ */
#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
static __no_kasan_or_inline
unsigned long read_word_at_a_time(const void *addr)
{
kasan_check_read(addr, 1);
return *(unsigned long *)addr;
}
#define WRITE_ONCE(x, val) \ #define WRITE_ONCE(x, val) \
({ \ ({ \
union { typeof(x) __val; char __c[1]; } __u = \ union { typeof(x) __val; char __c[1]; } __u = \
......
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