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| author | H. Peter Anvin <hpa@linux.intel.com> | 2014-02-13 07:34:30 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-22 13:34:51 -0800 |
| commit | 7eecce178e68a46923f5f9cb0a273b35f4bdedb9 (patch) | |
| tree | 3b0afcd4c7f5022f4d3061270caffc267aa6b1c3 | |
| parent | c2de2d3b28ed7ac53a14b5c1940de3fc527cdce3 (diff) | |
| download | lwn-7eecce178e68a46923f5f9cb0a273b35f4bdedb9.tar.gz lwn-7eecce178e68a46923f5f9cb0a273b35f4bdedb9.zip | |
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>
| -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 6abc172b8258..fe2bdd0f62c1 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 + } } /* |