linux-kernel - Re: kexec broken with STACKLEAK enabled

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Date:   Mon, 23 Sep 2019 09:15:16 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>
Subject: Re: kexec broken with STACKLEAK enabled

On Sun, Sep 22, 2019 at 10:32 AM Arvind Sankar <nivedita@...m.mit.edu> wrote:
>
> Hi, since commit b059f801a937 (x86/purgatory: Use CFLAGS_REMOVE rather
> than reset KBUILD_CFLAGS) kexec is broken if GCC_PLUGIN_STACKLEAK is
> enabled, as the purgatory contains undefined references to
> stackleak_track_stack.
>
> Attempting to load a kexec kernel results in an error:
>
>         kexec: Undefined symbol: stackleak_track_stack
>         kexec-bzImage64: Loading purgatory failed
>
> Adding $(DISABLE_STACKLEAK_PLUGIN) to PURGATORY_CFLAGS in
> arch/x86/purgatory/Makefile fixes this.

Hi Arvind,
Thanks for the report.  That sounds like a straightforward fix.  Would
you like to send a patch for that?  I'd be happy to help review it.

>
> Not sure if that's the best fix or if other architectures also require a
> similar one.

The commit you reference should be x86 only.
-- 
Thanks,
~Nick Desaulniers