| From 03bbd596ac04fef47ce93a730b8f086d797c3021 Mon Sep 17 00:00:00 2001 |
| From: "H. Peter Anvin" <hpa@linux.intel.com> |
| Date: Thu, 13 Feb 2014 07:34:30 -0800 |
| Subject: x86, smap: Don't enable SMAP if CONFIG_X86_SMAP is disabled |
| |
| From: "H. Peter Anvin" <hpa@linux.intel.com> |
| |
| 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> |
| |
| --- |
| arch/x86/kernel/cpu/common.c | 7 ++++++- |
| 1 file changed, 6 insertions(+), 1 deletion(-) |
| |
| --- a/arch/x86/kernel/cpu/common.c |
| +++ b/arch/x86/kernel/cpu/common.c |
| @@ -284,8 +284,13 @@ static __always_inline void setup_smap(s |
| 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 |
| + } |
| } |
| |
| /* |
