Make it all a function which does the WRMSR instead of having a hairy inline asm.
Signed-off-by: Borislav Petkov <[email protected]> --- arch/x86/include/asm/cpufeatures.h | 2 +- arch/x86/include/asm/nospec-branch.h | 13 ++++--------- arch/x86/include/asm/processor.h | 4 ++++ arch/x86/kernel/cpu/bugs.c | 7 +++++++ 4 files changed, 16 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 6c6d862d66a1..6c033f6adc24 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -211,7 +211,7 @@ #define X86_FEATURE_MBA ( 7*32+18) /* Memory Bandwidth Allocation */ #define X86_FEATURE_RSB_CTXSW ( 7*32+19) /* Fill RSB on context switches */ -#define X86_FEATURE_IBPB ( 7*32+21) /* Indirect Branch Prediction Barrier enabled*/ +#define X86_FEATURE_IBPB ( 7*32+21) /* Indirect Branch Prediction Barrier enabled */ /* Virtualization flags: Linux defined, word 8 */ #define X86_FEATURE_TPR_SHADOW ( 8*32+ 0) /* Intel TPR Shadow */ diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 4f88e1b2599f..71ae2dd65259 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -183,15 +183,10 @@ static inline void vmexit_fill_RSB(void) static inline void indirect_branch_prediction_barrier(void) { - asm volatile(ALTERNATIVE("", - "movl %[msr], %%ecx\n\t" - "movl %[val], %%eax\n\t" - "movl $0, %%edx\n\t" - "wrmsr", - X86_FEATURE_IBPB) - : : [msr] "i" (MSR_IA32_PRED_CMD), - [val] "i" (PRED_CMD_IBPB) - : "eax", "ecx", "edx", "memory"); + alternative_input("", + "call __ibp_barrier", + X86_FEATURE_IBPB, + ASM_NO_INPUT_CLOBBER("eax", "ecx", "edx", "memory")); } #endif /* __ASSEMBLY__ */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index d3a67fba200a..4d372f1cea5a 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -971,4 +971,8 @@ bool xen_set_default_idle(void); void stop_this_cpu(void *dummy); void df_debug(struct pt_regs *regs, long error_code); + +#ifdef CONFIG_RETPOLINE +void __ibp_barrier(void); +#endif #endif /* _ASM_X86_PROCESSOR_H */ diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index be068aea6bda..448410fcffcf 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -304,3 +304,10 @@ ssize_t cpu_show_spectre_v2(struct device *dev, spectre_v2_bad_module ? " - vulnerable module loaded" : ""); } #endif + +#ifdef CONFIG_RETPOLINE +void __ibp_barrier(void) +{ + __wrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0); +} +#endif -- 2.13.0 -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
