diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | arch/x86/include/asm/cpufeature.h | 1 | ||||
| -rw-r--r-- | arch/x86/include/asm/processor-flags.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 23 |
4 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 259037b873b7..c603ef7b0568 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -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) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 30afb465d486..5dc6acc98dbd 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -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__) diff --git a/arch/x86/include/asm/processor-flags.h b/arch/x86/include/asm/processor-flags.h index a898a2b6e10c..59ab4dffa377 100644 --- a/arch/x86/include/asm/processor-flags.h +++ b/arch/x86/include/asm/processor-flags.h @@ -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 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 173f3a3fa1a6..cbc70a27430c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -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); |