linux-kernel - Re: [PATCH 4/8] binfmt_elf: open code copy_siginfo_to

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Message-ID: <87o8rqc7az.fsf@x220.int.ebiederm.org>
Date:   Fri, 17 Apr 2020 13:10:12 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Christoph Hellwig <hch@....de>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jeremy Kerr <jk@...abs.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
        x86@...nel.org
Subject: Re: [PATCH 4/8] binfmt_elf: open code copy_siginfo_to_user to kernelspace buffer

Christoph Hellwig <hch@....de> writes:

> On Wed, Apr 15, 2020 at 10:20:11AM +0200, Arnd Bergmann wrote:
>> > I'd rather keep it out of this series and to
>> > an interested party.  Then again x32 doesn't seem to have a whole lot
>> > of interested parties..
>> 
>> Fine with me. It's on my mental list of things that we want to kill off
>> eventually as soon as the remaining users stop replying to questions
>> about it.
>> 
>> In fact I should really turn that into a properly maintained list in
>> Documentation/... that contains any options that someone has
>> asked about removing in the past, along with the reasons for keeping
>> it around and a time at which we should ask about it again.
>
> To the newly added x86 maintainers:  Arnd brought up the point that
> elf_core_dump writes the ABI siginfo format into the core dump. That
> format differs for i386 vs x32.  Is there any good way to find out
> which is the right format when are not in a syscall?
>
> As far a I can tell x32 vs i386 just seems to be based around what
> syscall table was used for the current syscall, but core dumps aren't
> always in syscall context.

I don't think this matters.  The i386 and x32 signal structures
only differ for SIGCHLD.  The SIGCHLD signal does cause coredumps.
So as long as we get the 32bit vs 64bit distinct correct all should be
well.

Eric