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

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Message-ID: <20240405175017.GFZhA52eQFEWrHPxV3@fat_crate.local>
Date: Fri, 5 Apr 2024 19:50:17 +0200
From: Borislav Petkov <bp@...en8.de>
To: bp@...nel.org
Cc: X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/retpoline: Add NOENDBR annotation to the SRSO dummy
 return thunk

On Fri, Apr 05, 2024 at 04:46:37PM +0200, bp@...nel.org wrote:
> From: "Borislav Petkov (AMD)" <bp@...en8.de>
> 
> 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) <bp@...en8.de>
> ---
>  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.

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