| Date | Mon, 14 Aug 2023 13:44:28 +0200 | From | Peter Zijlstra <> | Subject | [PATCH v2 02/11] x86/cpu: Fix up srso_safe_ret() and __x86_return_thunk() |
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vmlinux.o: warning: objtool: srso_untrain_ret() falls through to next function __x86_return_skl() vmlinux.o: warning: objtool: __x86_return_thunk() falls through to next function __x86_return_skl()
This is because these functions (can) end with CALL, which objtool does not consider a terminating instruction. Therefore replace the INT3 instruction (which is a non-fatal trap) with UD2 (which is a fatal-trap).
This indicates execution will not continue past this point.
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/x86/lib/retpoline.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -259,7 +259,7 @@ SYM_INNER_LABEL(srso_safe_ret, SYM_L_GLO int3 lfence call srso_safe_ret - int3 + ud2 SYM_CODE_END(srso_safe_ret) SYM_FUNC_END(srso_untrain_ret) __EXPORT_THUNK(srso_untrain_ret) @@ -269,7 +269,7 @@ SYM_CORE_START(__x86_return_thunk) ANNOTATE_NOENDBR ALTERNATIVE_2 "jmp __ret", "call srso_safe_ret", X86_FEATURE_SRSO, \ "call srso_safe_ret_alias", X86_FEATURE_SRSO_ALIAS - int3 + ud2 SYM_CODE_END(__x86_return_thunk) EXPORT_SYMBOL(__x86_return_thunk)
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