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authorH. Peter Anvin <hpa@linux.intel.com>2014-02-13 07:34:30 -0800
committerH. Peter Anvin <hpa@linux.intel.com>2014-02-13 07:50:25 -0800
commit03bbd596ac04fef47ce93a730b8f086d797c3021 (patch)
tree763dcbb9bab4588640392226e06789bc688db565 /arch
parenta9f180345f5378ac87d80ed0bea55ba421d83859 (diff)
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+
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/common.c7
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
+ }
}
/*