From: Peter Zijlstra peterz@infradead.org
stable inclusion from stable-v5.10.192 commit 06597b650beb49bffc61e077f41e39b830d72128 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7RQ67
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit e7c25c441e9e0fa75b4c83e0b26306b702cfe90d upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- arch/x86/include/asm/nospec-branch.h | 12 ++++-------- arch/x86/kernel/cpu/bugs.c | 1 + arch/x86/lib/retpoline.S | 7 +++++++ 3 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index e30a7e8c5758..546c339463e1 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -156,9 +156,9 @@ .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
/* @@ -177,14 +177,9 @@ defined(CONFIG_CPU_SRSO) ANNOTATE_UNRET_END ALTERNATIVE_2 "", \ - CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET, \ + CALL_UNTRAIN_RET, X86_FEATURE_UNRET, \ "call entry_ibpb", X86_FEATURE_ENTRY_IBPB #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
#else /* __ASSEMBLY__ */ @@ -209,6 +204,7 @@ 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);
#ifdef CONFIG_RETPOLINE diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index a8bb3494546e..a5c6bf2dbfa9 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2400,6 +2400,7 @@ 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 b5697ba1ca71..e807df6e56a7 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -230,6 +230,13 @@ 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