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| author | Peter Zijlstra <peterz@infradead.org> | 2019-04-03 09:39:48 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-04-03 11:02:19 +0200 |
| commit | e74deb11931ff682b59d5b9d387f7115f689698e (patch) | |
| tree | 6d9698ce16b48c95ecff5ca40f8b2701941b9583 /arch/x86/include/asm/smap.h | |
| parent | x86/uaccess, signal: Fix AC=1 bloat (diff) | |
| download | linux-e74deb11931ff682b59d5b9d387f7115f689698e.tar.xz linux-e74deb11931ff682b59d5b9d387f7115f689698e.zip | |
x86/uaccess: Introduce user_access_{save,restore}()
Introduce common helpers for when we need to safely suspend a
uaccess section; for instance to generate a {KA,UB}SAN report.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/smap.h')
| -rw-r--r-- | arch/x86/include/asm/smap.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/include/asm/smap.h b/arch/x86/include/asm/smap.h index db333300bd4b..6cfe43171020 100644 --- a/arch/x86/include/asm/smap.h +++ b/arch/x86/include/asm/smap.h @@ -58,6 +58,23 @@ static __always_inline void stac(void) alternative("", __stringify(__ASM_STAC), X86_FEATURE_SMAP); } +static __always_inline unsigned long smap_save(void) +{ + unsigned long flags; + + asm volatile (ALTERNATIVE("", "pushf; pop %0; " __stringify(__ASM_CLAC), + X86_FEATURE_SMAP) + : "=rm" (flags) : : "memory", "cc"); + + return flags; +} + +static __always_inline void smap_restore(unsigned long flags) +{ + asm volatile (ALTERNATIVE("", "push %0; popf", X86_FEATURE_SMAP) + : : "g" (flags) : "memory", "cc"); +} + /* These macros can be used in asm() statements */ #define ASM_CLAC \ ALTERNATIVE("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP) @@ -69,6 +86,9 @@ static __always_inline void stac(void) static inline void clac(void) { } static inline void stac(void) { } +static inline unsigned long smap_save(void) { return 0; } +static inline void smap_restore(unsigned long flags) { } + #define ASM_CLAC #define ASM_STAC |