x86/retpoline: Add NOENDBR annotation to the SRSO dummy return thunk

srso_alias_untrain_ret() is special code, even if it is a dummy
which is called in the !SRSO case, so annotate it like its real
counterpart, to address the following objtool splat:

  vmlinux.o: warning: objtool: .export_symbol+0x2b290: data relocation to !ENDBR: srso_alias_untrain_ret+0x0

Fixes: 4535e1a4174c ("x86/bugs: Fix the SRSO mitigation on Zen3/4")
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240405144637.17908-1-bp@kernel.org

diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 0795b3464058b0e515cb71d7bf84fa9908e6fc07..e674ccf720b9f6befe6ffb0fccec192fb1aa9a89 100644 (file)
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -229,6 +229,7 @@ SYM_CODE_END(srso_return_thunk)
 /* Dummy for the alternative in CALL_UNTRAIN_RET. */
 SYM_CODE_START(srso_alias_untrain_ret)
        ANNOTATE_UNRET_SAFE
+       ANNOTATE_NOENDBR
        ret
        int3
 SYM_FUNC_END(srso_alias_untrain_ret)