2024-04-05 14:46:46

by Borislav Petkov

Subject: [PATCH] x86/retpoline: Add NOENDBR annotation to the SRSO dummy return thunk

From: "Borislav Petkov (AMD)" <[email protected]>

It 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:

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

Signed-off-by: Borislav Petkov (AMD) <[email protected]>
---
arch/x86/lib/retpoline.S | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 0795b3464058..e674ccf720b9 100644
--- 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)
--
2.43.0

2024-04-05 17:50:37

by Borislav Petkov

Subject: Re: [PATCH] x86/retpoline: Add NOENDBR annotation to the SRSO dummy return thunk

On Fri, Apr 05, 2024 at 04:46:37PM +0200, [email protected] wrote:
> From: "Borislav Petkov (AMD)" <[email protected]>
>
> It 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:
>
> 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) <[email protected]>
> ---
> arch/x86/lib/retpoline.S | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
> index 0795b3464058..e674ccf720b9 100644
> --- 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)
> --
> 2.43.0
>

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

2024-04-06 11:07:35

by tip-bot2 for Jacob Pan

Subject: [tip: x86/urgent] x86/retpoline: Add NOENDBR annotation to the SRSO dummy return thunk

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: b377c66ae3509ccea596512d6afb4777711c4870
Gitweb: https://git.kernel.org/tip/b377c66ae3509ccea596512d6afb4777711c4870
Author: Borislav Petkov (AMD) <[email protected]>
AuthorDate: Fri, 05 Apr 2024 16:46:37 +02:00
Committer: Ingo Molnar <[email protected]>
CommitterDate: Sat, 06 Apr 2024 13:01:50 +02:00

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) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/lib/retpoline.S | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 0795b34..e674ccf 100644
--- 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)