[PATCH v2] x86/alternative: fix undefined reference to __ibt_endbr_seal[_end]

From: Miaohe Lin
Date: Mon Oct 10 2022 - 23:41:52 EST

Due to the explicit 'noinline' GCC-7.3 is not able to optimize away the
argument setup of:

apply_ibt_endbr(__ibt_endbr_seal, __ibt_enbr_seal_end);

even when X86_KERNEL_IBT=n and the function is an empty stub which leads
to link errors due to missing __ibt_endbr_seal* symbols like below:

ld: arch/x86/kernel/alternative.o: in function
alternative.c:(.init.text+0x15d): undefined reference to
ld: alternative.c:(.init.text+0x164): undefined reference to

Remove explicit 'noinline' to help gcc optimize them away.
[Thanks Peter Zijlstra for tweaking the commit log.]

Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
arch/x86/kernel/alternative.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 5cadcea035e0..beaf9fc44e2f 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -624,7 +624,7 @@ void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end)


-void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end) { }
+void __init_or_module apply_ibt_endbr(s32 *start, s32 *end) { }

#endif /* CONFIG_X86_KERNEL_IBT */