linux-kernel - Re: [PATCH 2/8] signal: clean up __copy_siginfo_to

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Date:   Fri, 17 Apr 2020 16:08:23 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Christoph Hellwig <hch@....de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jeremy Kerr <jk@...abs.org>, Arnd Bergmann <arnd@...db.de>,
        linuxppc-dev@...ts.ozlabs.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 2/8] signal: clean up __copy_siginfo_to_user32

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

> Instead of an architecture specific calling convention in common code
> just pass a flags argument with architecture specific values.

This bothers me because it makes all architectures pay for the sins of
x32.  Further it starts burying the details of the what is happening in
architecture specific helpers.  Hiding the fact that there is only
one niche architecture that does anything weird.

I am very sensitive to hiding away signal handling details right now
because way to much of the signal handling code got hidden in
architecture specific files and was quite buggy because as a result.

My general sense is putting all of the weird details up front and center
in kernel/signal.c is the only way for this code will be looked at
and successfully maintained.

How about these patches to solve set_fs with binfmt_elf instead:

Eric W. Biederman (2):
      signal: Factor copy_siginfo_to_external32 from copy_siginfo_to_user32
      signal: Remove the set_fs in binfmt_elf.c:fill_siginfo_note

 fs/binfmt_elf.c        |   5 +----
 fs/compat_binfmt_elf.c |   2 +-
 include/linux/compat.h |   1 +
 include/linux/signal.h |   7 +++++++
 kernel/signal.c        | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------------

Eric