linux-kernel - Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##]

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Message-ID: <20180515224354.zmygmsnlqj5lrdbo@treble>
Date:   Tue, 15 May 2018 17:43:54 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Alexey Dobriyan <adobriyan@...il.com>,
        Peter Anvin <h.peter.anvin@...el.com>,
        kernel test robot <xiaolong.ye@...el.com>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Brian Gerst <brgerst@...il.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Anvin <hpa@...or.com>, tipbuild@...or.com,
        LKP <lkp@...org>
Subject: Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##]

On Tue, May 15, 2018 at 03:28:19PM -0700, Linus Torvalds wrote:
> On Tue, May 15, 2018 at 3:22 PM Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> 
> > The padding isn't needed there, and the resume_userspace symbol is never
> > used, so wouldn't this fix it?
> 
> This looks like the correct fix for this case, but are we sure there aren't
> other cases where we have this same "fall through to an ENTRY" case?
> 
> Because we've definitely had that kind of code before too - sometimes
> simply because we want profiles and oopses to show which "part" of the asm
> we're faulting in (that could be the case here too).

Glancing through the 32-bit and 64-bit entry code, I didn't see any more
cases.  At least it will fail loudly if any such cases do still exist.

-- 
Josh