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| author | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 12:43:12 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 12:45:27 -0700 |
| commit | 63bcff2a307b9bcc712a8251eb27df8b2e117967 (patch) | |
| tree | 0a23a378d2c967edf63e9bb2b5df2288bf30859c /arch/x86/include/asm/smap.h | |
| parent | a052858fabb376b695f2c125633daa6728e0f284 (diff) | |
| download | linux-0-day-63bcff2a307b9bcc712a8251eb27df8b2e117967.tar.gz linux-0-day-63bcff2a307b9bcc712a8251eb27df8b2e117967.tar.xz | |
x86, smap: Add STAC and CLAC instructions to control user space access
When Supervisor Mode Access Prevention (SMAP) is enabled, access to
userspace from the kernel is controlled by the AC flag. To make the
performance of manipulating that flag acceptable, there are two new
instructions, STAC and CLAC, to set and clear it.
This patch adds those instructions, via alternative(), when the SMAP
feature is enabled. It also adds X86_EFLAGS_AC unconditionally to the
SYSCALL entry mask; there is simply no reason to make that one
conditional.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-9-git-send-email-hpa@linux.intel.com
Diffstat (limited to 'arch/x86/include/asm/smap.h')
| -rw-r--r-- | arch/x86/include/asm/smap.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/smap.h b/arch/x86/include/asm/smap.h index 3989c2492eb5f..8d3120f4e2705 100644 --- a/arch/x86/include/asm/smap.h +++ b/arch/x86/include/asm/smap.h @@ -58,13 +58,13 @@ #ifdef CONFIG_X86_SMAP -static inline void clac(void) +static __always_inline void clac(void) { /* Note: a barrier is implicit in alternative() */ alternative(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP); } -static inline void stac(void) +static __always_inline void stac(void) { /* Note: a barrier is implicit in alternative() */ alternative(ASM_NOP3, __stringify(__ASM_STAC), X86_FEATURE_SMAP); |