diff options
Diffstat (limited to 'arch/x86/include/asm/nospec-branch.h')
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 68 |
1 files changed, 49 insertions, 19 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 62f9903544b5..8dba996e9f9e 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -9,6 +9,7 @@ #include <asm/alternative-asm.h> #include <asm/cpufeatures.h> #include <asm/msr-index.h> +#include <asm/percpu.h> /* * Fill the CPU return stack buffer. @@ -35,6 +36,7 @@ * the optimal version — two calls, each with their own speculation * trap should their return address end up getting used, in a loop. */ +#ifdef CONFIG_X86_64 #define __FILL_RETURN_BUFFER(reg, nr, sp) \ mov $(nr/2), reg; \ 771: \ @@ -52,7 +54,29 @@ 774: \ dec reg; \ jnz 771b; \ + add $(BITS_PER_LONG/8) * nr, sp; \ + /* barrier for jnz misprediction */ \ + lfence; +#else +/* + * i386 doesn't unconditionally have LFENCE, as such it can't + * do a loop. + */ +#define __FILL_RETURN_BUFFER(reg, nr, sp) \ + .rept nr; \ + call 772f; \ + int3; \ +772:; \ + .endr; \ add $(BITS_PER_LONG/8) * nr, sp; +#endif + +#define ISSUE_UNBALANCED_RET_GUARD(sp) \ + call 992f; \ + int3; \ +992: \ + add $(BITS_PER_LONG/8), sp; \ + lfence; #ifdef __ASSEMBLY__ @@ -119,7 +143,7 @@ ANNOTATE_NOSPEC_ALTERNATIVE ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *\reg), \ __stringify(RETPOLINE_JMP \reg), X86_FEATURE_RETPOLINE, \ - __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *\reg), X86_FEATURE_RETPOLINE_AMD + __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *\reg), X86_FEATURE_RETPOLINE_LFENCE #else jmp *\reg #endif @@ -130,7 +154,7 @@ ANNOTATE_NOSPEC_ALTERNATIVE ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *\reg), \ __stringify(RETPOLINE_CALL \reg), X86_FEATURE_RETPOLINE,\ - __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *\reg), X86_FEATURE_RETPOLINE_AMD + __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *\reg), X86_FEATURE_RETPOLINE_LFENCE #else call *\reg #endif @@ -141,13 +165,11 @@ * monstrosity above, manually. */ .macro FILL_RETURN_BUFFER reg:req nr:req ftr:req -#ifdef CONFIG_RETPOLINE ANNOTATE_NOSPEC_ALTERNATIVE ALTERNATIVE "jmp .Lskip_rsb_\@", \ __stringify(__FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP)) \ \ftr .Lskip_rsb_\@: -#endif .endm #else /* __ASSEMBLY__ */ @@ -181,7 +203,7 @@ "lfence;\n" \ ANNOTATE_RETPOLINE_SAFE \ "call *%[thunk_target]\n", \ - X86_FEATURE_RETPOLINE_AMD) + X86_FEATURE_RETPOLINE_LFENCE) # define THUNK_TARGET(addr) [thunk_target] "r" (addr) #else /* CONFIG_X86_32 */ @@ -211,7 +233,7 @@ "lfence;\n" \ ANNOTATE_RETPOLINE_SAFE \ "call *%[thunk_target]\n", \ - X86_FEATURE_RETPOLINE_AMD) + X86_FEATURE_RETPOLINE_LFENCE) # define THUNK_TARGET(addr) [thunk_target] "rm" (addr) #endif @@ -223,9 +245,12 @@ /* The Spectre V2 mitigation variants */ enum spectre_v2_mitigation { SPECTRE_V2_NONE, - SPECTRE_V2_RETPOLINE_GENERIC, - SPECTRE_V2_RETPOLINE_AMD, - SPECTRE_V2_IBRS_ENHANCED, + SPECTRE_V2_RETPOLINE, + SPECTRE_V2_LFENCE, + SPECTRE_V2_EIBRS, + SPECTRE_V2_EIBRS_RETPOLINE, + SPECTRE_V2_EIBRS_LFENCE, + SPECTRE_V2_IBRS, }; /* The indirect branch speculation control variants */ @@ -254,15 +279,17 @@ extern char __indirect_thunk_end[]; * retpoline and IBRS mitigations for Spectre v2 need this; only on future * CPUs with IBRS_ALL *might* it be avoided. */ -static inline void vmexit_fill_RSB(void) +static __always_inline void vmexit_fill_RSB(void) { #ifdef CONFIG_RETPOLINE unsigned long loops; asm volatile (ANNOTATE_NOSPEC_ALTERNATIVE - ALTERNATIVE("jmp 910f", - __stringify(__FILL_RETURN_BUFFER(%0, RSB_CLEAR_LOOPS, %1)), - X86_FEATURE_RETPOLINE) + ALTERNATIVE_2("jmp 910f", "", X86_FEATURE_RSB_VMEXIT, + "jmp 911f", X86_FEATURE_RSB_VMEXIT_LITE) + __stringify(__FILL_RETURN_BUFFER(%0, RSB_CLEAR_LOOPS, %1)) + "911:" + __stringify(ISSUE_UNBALANCED_RET_GUARD(%1)) "910:" : "=r" (loops), ASM_CALL_CONSTRAINT : : "memory" ); @@ -289,6 +316,9 @@ static inline void indirect_branch_prediction_barrier(void) /* The Intel SPEC CTRL MSR base value cache */ extern u64 x86_spec_ctrl_base; +DECLARE_PER_CPU(u64, x86_spec_ctrl_current); +extern void update_spec_ctrl_cond(u64 val); +extern u64 spec_ctrl_current(void); /* * With retpoline, we must use IBRS to restrict branch prediction @@ -298,18 +328,16 @@ extern u64 x86_spec_ctrl_base; */ #define firmware_restrict_branch_speculation_start() \ do { \ - u64 val = x86_spec_ctrl_base | SPEC_CTRL_IBRS; \ - \ preempt_disable(); \ - alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \ + alternative_msr_write(MSR_IA32_SPEC_CTRL, \ + spec_ctrl_current() | SPEC_CTRL_IBRS, \ X86_FEATURE_USE_IBRS_FW); \ } while (0) #define firmware_restrict_branch_speculation_end() \ do { \ - u64 val = x86_spec_ctrl_base; \ - \ - alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \ + alternative_msr_write(MSR_IA32_SPEC_CTRL, \ + spec_ctrl_current(), \ X86_FEATURE_USE_IBRS_FW); \ preempt_enable(); \ } while (0) @@ -321,6 +349,8 @@ DECLARE_STATIC_KEY_FALSE(switch_mm_always_ibpb); DECLARE_STATIC_KEY_FALSE(mds_user_clear); DECLARE_STATIC_KEY_FALSE(mds_idle_clear); +DECLARE_STATIC_KEY_FALSE(mmio_stale_data_clear); + #include <asm/segment.h> /** |