diff options
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 39 |
1 files changed, 25 insertions, 14 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 81cf716f6f97..4e8d25d395ee 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -801,6 +801,31 @@ static void detect_nopl(struct cpuinfo_x86 *c) #else set_cpu_cap(c, X86_FEATURE_NOPL); #endif + + /* + * ESPFIX is a strange bug. All real CPUs have it. Paravirt + * systems that run Linux at CPL > 0 may or may not have the + * issue, but, even if they have the issue, there's absolutely + * nothing we can do about it because we can't use the real IRET + * instruction. + * + * NB: For the time being, only 32-bit kernels support + * X86_BUG_ESPFIX as such. 64-bit kernels directly choose + * whether to apply espfix using paravirt hooks. If any + * non-paravirt system ever shows up that does *not* have the + * ESPFIX issue, we can change this. + */ +#ifdef CONFIG_X86_32 +#ifdef CONFIG_PARAVIRT + do { + extern void native_iret(void); + if (pv_cpu_ops.iret == native_iret) + set_cpu_bug(c, X86_BUG_ESPFIX); + } while (0); +#else + set_cpu_bug(c, X86_BUG_ESPFIX); +#endif +#endif } static void generic_identify(struct cpuinfo_x86 *c) @@ -1475,20 +1500,6 @@ void cpu_init(void) } #endif -#ifdef CONFIG_X86_DEBUG_STATIC_CPU_HAS -void warn_pre_alternatives(void) -{ - WARN(1, "You're using static_cpu_has before alternatives have run!\n"); -} -EXPORT_SYMBOL_GPL(warn_pre_alternatives); -#endif - -inline bool __static_cpu_has_safe(u16 bit) -{ - return boot_cpu_has(bit); -} -EXPORT_SYMBOL_GPL(__static_cpu_has_safe); - static void bsp_resume(void) { if (this_cpu->c_bsp_resume) |