diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-08-14 14:44:34 +0300 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-08-16 22:58:59 +0300 |
| commit | e7c25c441e9e0fa75b4c83e0b26306b702cfe90d (patch) | |
| tree | d1b84a9257747a38b463571a41e63181b5252be1 /arch | |
| parent | 42be649dd1f2eee6b1fb185f1a231b9494cf095f (diff) | |
| download | linux-e7c25c441e9e0fa75b4c83e0b26306b702cfe90d.tar.xz | |
x86/cpu: Cleanup the untrain mess
Since there can only be one active return_thunk, there only needs be
one (matching) untrain_ret. It fundamentally doesn't make sense to
allow multiple untrain_ret at the same time.
Fold all the 3 different untrain methods into a single (temporary)
helper stub.
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121149.042774962@infradead.org
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 19 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 1 | ||||
| -rw-r--r-- | arch/x86/lib/retpoline.S | 7 |
3 files changed, 13 insertions, 14 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index f7c337515d1e..5285c8e93dff 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -272,9 +272,9 @@ .endm #ifdef CONFIG_CPU_UNRET_ENTRY -#define CALL_ZEN_UNTRAIN_RET "call retbleed_untrain_ret" +#define CALL_UNTRAIN_RET "call entry_untrain_ret" #else -#define CALL_ZEN_UNTRAIN_RET "" +#define CALL_UNTRAIN_RET "" #endif /* @@ -293,15 +293,10 @@ defined(CONFIG_CALL_DEPTH_TRACKING) || defined(CONFIG_CPU_SRSO) VALIDATE_UNRET_END ALTERNATIVE_3 "", \ - CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET, \ + CALL_UNTRAIN_RET, X86_FEATURE_UNRET, \ "call entry_ibpb", X86_FEATURE_ENTRY_IBPB, \ __stringify(RESET_CALL_DEPTH), X86_FEATURE_CALL_DEPTH #endif - -#ifdef CONFIG_CPU_SRSO - ALTERNATIVE_2 "", "call srso_untrain_ret", X86_FEATURE_SRSO, \ - "call srso_alias_untrain_ret", X86_FEATURE_SRSO_ALIAS -#endif .endm .macro UNTRAIN_RET_FROM_CALL @@ -309,15 +304,10 @@ defined(CONFIG_CALL_DEPTH_TRACKING) VALIDATE_UNRET_END ALTERNATIVE_3 "", \ - CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET, \ + CALL_UNTRAIN_RET, X86_FEATURE_UNRET, \ "call entry_ibpb", X86_FEATURE_ENTRY_IBPB, \ __stringify(RESET_CALL_DEPTH_FROM_CALL), X86_FEATURE_CALL_DEPTH #endif - -#ifdef CONFIG_CPU_SRSO - ALTERNATIVE_2 "", "call srso_untrain_ret", X86_FEATURE_SRSO, \ - "call srso_alias_untrain_ret", X86_FEATURE_SRSO_ALIAS -#endif .endm @@ -355,6 +345,7 @@ extern void retbleed_untrain_ret(void); extern void srso_untrain_ret(void); extern void srso_alias_untrain_ret(void); +extern void entry_untrain_ret(void); extern void entry_ibpb(void); extern void (*x86_return_thunk)(void); diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index bbbbda981bab..6f3e19527286 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2460,6 +2460,7 @@ static void __init srso_select_mitigation(void) * like ftrace, static_call, etc. */ setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_UNRET); if (boot_cpu_data.x86 == 0x19) { setup_force_cpu_cap(X86_FEATURE_SRSO_ALIAS); diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index d37e5ab0d5ee..5e85da150e96 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -289,6 +289,13 @@ SYM_CODE_START(srso_return_thunk) ud2 SYM_CODE_END(srso_return_thunk) +SYM_FUNC_START(entry_untrain_ret) + ALTERNATIVE_2 "jmp retbleed_untrain_ret", \ + "jmp srso_untrain_ret", X86_FEATURE_SRSO, \ + "jmp srso_alias_untrain_ret", X86_FEATURE_SRSO_ALIAS +SYM_FUNC_END(entry_untrain_ret) +__EXPORT_THUNK(entry_untrain_ret) + SYM_CODE_START(__x86_return_thunk) UNWIND_HINT_FUNC ANNOTATE_NOENDBR |