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kasan: add tag related helper functions

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This commit adds a few helper functions, that are meant to be used to work
with tags embedded in the top byte of kernel pointers: to set, to get or
to reset the top byte.

Link: http://lkml.kernel.org/r/f6c6437bb8e143bc44f42c3c259c62e734be7935.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.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
2018-12-28 00:30:16 -08:00
committed by Linus Torvalds
parent 9c23f84723
commit 3c9e3aa110
6 changed files with 101 additions and 2 deletions
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12
arch/arm64/include/asm/memory.h
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@@ -226,6 +226,18 @@ extern u64 vabits_user;
#define untagged_addr(addr) \
((__typeof__(addr))sign_extend64((u64)(addr), 55))
#ifdef CONFIG_KASAN_SW_TAGS
#define __tag_shifted(tag) ((u64)(tag) << 56)
#define __tag_set(addr, tag) (__typeof__(addr))( \
((u64)(addr) & ~__tag_shifted(0xff)) | __tag_shifted(tag))
#define __tag_reset(addr) untagged_addr(addr)
#define __tag_get(addr) (__u8)((u64)(addr) >> 56)
#else
#define __tag_set(addr, tag) (addr)
#define __tag_reset(addr) (addr)
#define __tag_get(addr) 0
#endif
/*
* Physical vs virtual RAM address space conversion. These are
* private definitions which should NOT be used outside memory.h