diff options
| author | H. Peter Anvin <hpa@linux.intel.com> | 2014-02-13 19:34:30 +0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2014-02-13 19:50:25 +0400 |
| commit | 03bbd596ac04fef47ce93a730b8f086d797c3021 (patch) | |
| tree | 763dcbb9bab4588640392226e06789bc688db565 | |
| parent | a9f180345f5378ac87d80ed0bea55ba421d83859 (diff) | |
| download | linux-03bbd596ac04fef47ce93a730b8f086d797c3021.tar.xz | |
x86, smap: Don't enable SMAP if CONFIG_X86_SMAP is disabled
If SMAP support is not compiled into the kernel, don't enable SMAP in
CR4 -- in fact, we should clear it, because the kernel doesn't contain
the proper STAC/CLAC instructions for SMAP support.
Found by Fengguang Wu's test system.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhost
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.7+
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 24b6fd10625a..8e28bf2fc3ef 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -284,8 +284,13 @@ static __always_inline void setup_smap(struct cpuinfo_x86 *c) raw_local_save_flags(eflags); BUG_ON(eflags & X86_EFLAGS_AC); - if (cpu_has(c, X86_FEATURE_SMAP)) + if (cpu_has(c, X86_FEATURE_SMAP)) { +#ifdef CONFIG_X86_SMAP set_in_cr4(X86_CR4_SMAP); +#else + clear_in_cr4(X86_CR4_SMAP); +#endif + } } /* |