linux-kernel - Re: [PATCH 1/3] Revert "x86/retpoline: Remove .text..__x86.return

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Message-ID: <ZSck4mcr6sKS/ob7@gmail.com>
Date:   Thu, 12 Oct 2023 00:42:42 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Josh Poimboeuf <jpoimboe@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        David Kaplan <david.kaplan@....com>, x86@...nel.org,
        luto@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] Revert "x86/retpoline: Remove
 .text..__x86.return_thunk section"

* Peter Zijlstra <peterz@...radead.org> wrote:

> I don't care too deeply, I can't make up my mind either way. But perhaps 
> keeping the section is easier on all the backports, it's easy to forget a 
> tiny objtool patch like this.

If the objtool fix has a Fixes tag that points to one of the major 
mitigation commits, then it won't be forgotten.

Arguably the new objtool is more robust against what could happen, so that 
patch is not going away - and with that patch mainline doesn't have to keep 
the (now ...) pointless section.

Maybe change the commit order around: first add the objtool fix, then 
remove the section, pointing back to the objtool SHA1 in the very next 
commit, explaining that the objtool fix enables this change. That makes it 
all backporting-proof as well.

Thanks,

	Ingo