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authorH. Peter Anvin <hpa@linux.intel.com>2014-02-13 07:34:30 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-22 12:41:27 -0800
commit1416612d2bf41f0a118087847c9b6a8fcd9c87da (patch)
tree18652f160752bf7fe08cc107fff65681a58a074e /arch
parent016085b4fe767ae73637585369104058493ffd72 (diff)
downloadlinaro-lsk-1416612d2bf41f0a118087847c9b6a8fcd9c87da.tar.gz
x86, smap: Don't enable SMAP if CONFIG_X86_SMAP is disabled
commit 03bbd596ac04fef47ce93a730b8f086d797c3021 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 22018f70a67..deeb48d9459 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
+ }
}
/*