From: Peter Zijlstra peterz@infradead.org
commit af023ef335f13c8b579298fc432daeef609a9e60 upstream.
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 Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/r/20230814121148.637802730@infradead.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.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 @@ -202,7 +202,7 @@ 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) @@ -212,7 +212,7 @@ SYM_CODE_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)