Commit 03bbd596 authored by H. Peter Anvin's avatar H. Peter Anvin

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: default avatarFengguang Wu <fengguang.wu@intel.com>
Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhostSigned-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.7+
parent a9f18034
...@@ -284,8 +284,13 @@ static __always_inline void setup_smap(struct cpuinfo_x86 *c) ...@@ -284,8 +284,13 @@ static __always_inline void setup_smap(struct cpuinfo_x86 *c)
raw_local_save_flags(eflags); raw_local_save_flags(eflags);
BUG_ON(eflags & X86_EFLAGS_AC); 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); set_in_cr4(X86_CR4_SMAP);
#else
clear_in_cr4(X86_CR4_SMAP);
#endif
}
} }
/* /*
......
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