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Merge branch 'x86-smep-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 

* 'x86-smep-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, cpu: Enable/disable Supervisor Mode Execution Protection
  x86, cpu: Add SMEP CPU feature in CR4
  x86, cpufeature: Add cpufeature flag for SMEP
This commit is contained in:
Linus Torvalds 2011-05-19 18:10:17 -07:00
parent 08839ff827 de5397ad5b
commit 5765040ebf
4 changed files with 29 additions and 0 deletions
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4
Documentation/kernel-parameters.txt
View File

@ -1664,6 +1664,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
noexec=on: enable non-executable mappings (default)
noexec=off: disable non-executable mappings
nosmep [X86]
Disable SMEP (Supervisor Mode Execution Protection)
even if it is supported by processor.
noexec32 [X86-64]
This affects only 32-bit executables.
noexec32=on: enable non-executable mappings (default)

1
arch/x86/include/asm/cpufeature.h
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@ -195,6 +195,7 @@
/* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 9 */
#define X86_FEATURE_FSGSBASE (9*32+ 0) /* {RD/WR}{FS/GS}BASE instructions*/
#define X86_FEATURE_SMEP (9*32+ 7) /* Supervisor Mode Execution Protection */
#define X86_FEATURE_ERMS (9*32+ 9) /* Enhanced REP MOVSB/STOSB */
#if defined(__KERNEL__) && !defined(__ASSEMBLY__)

1
arch/x86/include/asm/processor-flags.h
View File

@ -60,6 +60,7 @@
#define X86_CR4_OSXMMEXCPT 0x00000400 /* enable unmasked SSE exceptions */
#define X86_CR4_VMXE 0x00002000 /* enable VMX virtualization */
#define X86_CR4_OSXSAVE 0x00040000 /* enable xsave and xrestore */
#define X86_CR4_SMEP 0x00100000 /* enable SMEP support */
/*
* x86-64 Task Priority Register, CR8

23
arch/x86/kernel/cpu/common.c
View File

@ -254,6 +254,25 @@ static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
}
#endif
static int disable_smep __initdata;
static __init int setup_disable_smep(char *arg)
{
disable_smep = 1;
return 1;
}
__setup("nosmep", setup_disable_smep);
static __init void setup_smep(struct cpuinfo_x86 *c)
{
if (cpu_has(c, X86_FEATURE_SMEP)) {
if (unlikely(disable_smep)) {
setup_clear_cpu_cap(X86_FEATURE_SMEP);
clear_in_cr4(X86_CR4_SMEP);
} else
set_in_cr4(X86_CR4_SMEP);
}
}
/*
* Some CPU features depend on higher CPUID levels, which may not always
* be available due to CPUID level capping or broken virtualization
@ -667,6 +686,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
c->cpu_index = 0;
#endif
filter_cpuid_features(c, false);
setup_smep(c);
}
void __init early_cpu_init(void)
@ -752,6 +773,8 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
#endif
}
setup_smep(c);
get_model_name(c); /* Default name */
detect_nopl(c);