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Date: Wed, 3 Jan 2018 13:05:38 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Lars Wendler <wendler.lars@web.de>
cc: LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        Borislav Betkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Greg KH <gregkh@linuxfoundation.org>
Subject: Re: CONFIG_PAGE_TABLE_ISOLATION=y on x86_64 causes gcc to segfault
 when building x86_32 binaries
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On Wed, 3 Jan 2018, Thomas Gleixner wrote:
> On Wed, 3 Jan 2018, Lars Wendler wrote:
> Thanks for the report.
> 
> > I already had a conversation with Thomas Gleixner about this issue and
> > he asked me to post it here.
> > 
> > After upgrading my system to vanilla 4.14.11 kernel with
> > CONFIG_PAGE_TABLE_ISOLATION=y I could no longer build any 32bit
> > binaries because gcc (7.2.0) segfaults.
> 
> That's a 64bit binary, right?
> 
> > This only happens with CONFIG_PAGE_TABLE_ISOLATION=y
> > I can get rid of this issue by setting CONFIG_PAGE_TABLE_ISOLATION=n
> > _or_ adding pti=off to the kernel command line (the latter was
> > suggested by Thomas).
> > 
> > Please find attached the kernel's config together with the dmesg output
> > of the kernel that produces segfaults and the one with pti=off. I also
> > attached a config.log file from a build where gcc segfaulted.
> > 
> > If you need more information, please don't hesitate to ask.
> 
> will do.

Here you go.

Is this anything special you are trying to build or is a simple

   gcc -m32 -o hello hello.c

Also can you please try Linus v4.15-rc6 with PTI enabled so we can see
whether that's a backport issue or a general one?

Thanks,

	tglx