linux-kernel - Re: [PATCH v2 10/39] x86/ibt,crypto: Add ENDBR for the jump-table entries

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Message-ID: <202202241648.C349B75@keescook>
Date:   Thu, 24 Feb 2022 16:50:40 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, joao@...rdrivepizza.com, hjl.tools@...il.com,
        jpoimboe@...hat.com, andrew.cooper3@...rix.com,
        linux-kernel@...r.kernel.org, ndesaulniers@...gle.com,
        samitolvanen@...gle.com, mark.rutland@....com,
        alyssa.milburn@...el.com, mbenes@...e.cz, rostedt@...dmis.org,
        mhiramat@...nel.org, alexei.starovoitov@...il.com
Subject: Re: [PATCH v2 10/39] x86/ibt,crypto: Add ENDBR for the jump-table
 entries

On Thu, Feb 24, 2022 at 03:51:48PM +0100, Peter Zijlstra wrote:
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Can you put some details in the commit log here about why these are
needed? My eyes can't find the indirect users...

> ---
>  arch/x86/crypto/crc32c-pcl-intel-asm_64.S |    3 +++
>  1 file changed, 3 insertions(+)
> 
> --- a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
> +++ b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
> @@ -195,6 +195,7 @@ SYM_FUNC_START(crc_pcl)
>  .altmacro
>  LABEL crc_ %i
>  .noaltmacro
> +	ENDBR
>  	crc32q   -i*8(block_0), crc_init
>  	crc32q   -i*8(block_1), crc1
>  	crc32q   -i*8(block_2), crc2
> @@ -203,6 +204,7 @@ LABEL crc_ %i

-- 
Kees Cook