linux-kernel - Re: [PATCH 0/2] Stop generating .eh

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Message-ID: <CAKwvOd=wGYRPY32P3xA-WGG5FiNYk-S6BrjLw3nRqcQ3X0oPFg@mail.gmail.com>
Date:   Mon, 24 Feb 2020 14:01:38 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Arvind Sankar <nivedita@...m.mit.edu>,
        Borislav Petkov <bp@...en8.de>
Cc:     Nathan Chancellor <natechancellor@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Michael Matz <matz@...e.de>, Fangrui Song <maskray@...gle.com>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 0/2] Stop generating .eh_frame sections

On Mon, Feb 24, 2020 at 1:53 PM Arvind Sankar <nivedita@...m.mit.edu> wrote:
>
> On Mon, Feb 24, 2020 at 12:49:03PM -0800, Nick Desaulniers wrote:
> > On Sun, Feb 23, 2020 at 11:37 AM Arvind Sankar <nivedita@...m.mit.edu> wrote:
> > >
> > > In three places in the x86 kernel we are currently generating .eh_frame
> > > sections only to discard them later via linker script. This is in the
> > > boot code (setup.elf), the realmode trampoline (realmode.elf) and the
> > > compressed kernel.
> > >
> > > Implement Fangrui and Nick's suggestion [1] to fix KBUILD_CFLAGS by
> > > adding -fno-asynchronous-unwind-tables to avoid generating .eh_frame
> > > sections in the first place, rather than discarding it in the linker
> > > script.
> > >
> > > Arvind Sankar (2):
> > >   arch/x86: Use -fno-asynchronous-unwind-tables to suppress .eh_frame sections
> > >   arch/x86: Drop unneeded linker script discard of .eh_frame
> >
> > Thanks for the series! I've left some feedback for a v2. Would you
> > mind please including a revert of ("x86/boot/compressed: Remove
> > unnecessary sections from bzImage") in a v2 series?  Our CI being red
> > through the weekend is no bueno.
>
> Sorry about that. Boris already updated tip:x86/boot to only discard
> eh_frame, so your CI should be ok at least now.

Yep: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=x86/boot&id=0eea39a234dc52063d14541fabcb2c64516a2328
Looks like our daily CI ran 6 hours ago just missed it:
https://travis-ci.com/ClangBuiltLinux/continuous-integration/jobs/290435629
Thanks for the fix!

-- 
Thanks,
~Nick Desaulniers