linux-kernel - Re: [PATCH 00/22] x86, objtool: several fixes/improvements

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Message-ID: <20190715193834.5tvzukcwq735ufgb@treble>
Date:   Mon, 15 Jul 2019 14:38:34 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH 00/22] x86, objtool: several fixes/improvements

On Sun, Jul 14, 2019 at 07:36:55PM -0500, Josh Poimboeuf wrote:
> There have been a lot of objtool bug reports lately, mainly related to
> Clang and BPF.  As part of fixing those bugs, I added some improvements
> to objtool which uncovered yet more bugs (some kernel, some objtool).
> 
> I've given these patches a lot of testing with both GCC and Clang.  More
> compile testing of objtool would be appreciated, as the kbuild test
> robot doesn't seem to be paying much attention to my branches lately.
> 
> There are still at least three outstanding issues:
> 
> 1) With clang I see:
> 
>      drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x88: redundant UACCESS disable
> 
>    I haven't dug into it yet.
> 
> 2) There's also an issue in clang where a large switch table had a bunch
>    of unused (bad) entries.  It's not a code correctness issue, but
>    hopefully it can get fixed in clang anyway.  See patch 20/22 for more
>    details.
> 
> 3) CONFIG_LIVEPATCH is causing some objtool "unreachable instruction"
>    warnings due to the new -flive-patching flag.  I have some fixes
>    pending, but this patch set is already long enough.

These patches are also at:

  git://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git objtool-many-fixes

-- 
Josh