linux-kernel - Re: [PATCH] x86/microcode: move @microcode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230324164445.GEZB3Tfe7pRV+GgE4f@fat_crate.local>
Date:   Fri, 24 Mar 2023 17:44:45 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     John Ogness <john.ogness@...utronix.de>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/microcode: move @microcode_mutex definition near
 usage

On Fri, Mar 24, 2023 at 05:39:35PM +0106, John Ogness wrote:
> Note that an unused mutex is being defined, even when the compiler is
> not warning about it.

Are you sure?

$ make arch/x86/kernel/cpu/microcode/core.s
grep microcode_mutex arch/x86/kernel/cpu/microcode/core.s
$ 
$ make CC=clang arch/x86/kernel/cpu/microcode/core.s
$ grep microcode_mutex arch/x86/kernel/cpu/microcode/core.s
$ 

Looks to me like it gets optimized away.

> OK, but the kernel test robots will probably beat me to it. ;-)

That's exactly the question: they haven't because this is not a new
situation. Their compilers are optimizing unused stuff away too.

:-)

-- 
Regards/Gruss,
    Boris.

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