From: Ralf Baechle <ralf@linux-mips.org>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: linux-mips <linux-mips@linux-mips.org>,
Wu Zhangjin <wuzhangjin@gmail.com>
Subject: Re: [PATCH 0/6] mips: diverse Makefile updates
Date: Mon, 31 May 2010 11:29:54 +0100 [thread overview]
Message-ID: <20100531102954.GA12669@linux-mips.org> (raw)
In-Reply-To: <20100530231954.GA318@linux-mips.org>
On Mon, May 31, 2010 at 12:19:54AM +0100, Ralf Baechle wrote:
> > > Note: I tried to test a little with bigsur_defconfig
> > > but get_user() is buggy. Or at least my gcc thinks that
> > > first argument may be used uninitialized.
> > > I think mips needs to fix the 64 bit variant of get_user().
> > > I took a quick look but ran away.
> >
> > My gcc:
> > mips-linux-gcc (GCC) 4.1.2
> > Copyright (C) 2006 Free Software Foundation, Inc.
I played with it for a bit. The warning is present in all gcc 4.1.0 to
4.1.2 and it is bogus. When I first looked into this years ago I just
gave up on gcc 4.1 as a newer version was already available.
The variable returned by get_user is undefined in case of an error, so
what get_user() is doing is entirely legitimate. This is different from
copy_from_user() which in case of an error will clear the remainder of
the destination area which couldn't not be copied from userspace.
A test compile of a bigsur_defconfig without and with your patch shows
a size increase of only 80 bytes with gcc 4.5.0. So I'm considering
your patch for inclusion but I want to play with alternatives for a bit.
Outlining may the right thing with modern compilers.
Ralf
next prev parent reply other threads:[~2010-05-31 10:30 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-30 14:19 [PATCH 0/6] mips: diverse Makefile updates Sam Ravnborg
2010-05-30 14:26 ` [PATCH 1/6] mips: introduce arch/mips/Kbuild Sam Ravnborg
2010-05-30 14:26 ` [PATCH 2/6] mips: add -Werror to arch/mips/Kbuild Sam Ravnborg
2010-05-30 14:27 ` [PATCH 3/6] mips: introduce support for Platform definitions Sam Ravnborg
2010-05-30 14:27 ` [PATCH 4/6] mips: refactor arch/mips/boot/Makefile Sam Ravnborg
2010-05-30 14:28 ` [PATCH 5/6] mips: refactor arch/mips/boot/compressed/Makefile Sam Ravnborg
2010-05-30 14:28 ` [PATCH 6/6] mips: clean up arch/mips/Makefile Sam Ravnborg
2010-05-30 15:39 ` [PATCH 0/6] mips: diverse Makefile updates Sam Ravnborg
2010-05-30 23:19 ` Ralf Baechle
2010-05-31 10:29 ` Ralf Baechle [this message]
2010-05-31 10:55 ` Sam Ravnborg
2010-06-01 10:28 ` Ralf Baechle
2010-05-30 18:03 ` [ Sam Ravnborg
2010-05-30 18:06 ` [PATCH] mips: fix uninitialized warning when using get_user() Sam Ravnborg
2010-05-31 8:45 ` [PATCH 0/6] mips: diverse Makefile updates Wu Zhangjin
2010-05-31 9:10 ` Sam Ravnborg
2010-05-31 14:56 ` Ralf Baechle
2010-05-31 15:33 ` Manuel Lauss
2010-05-31 18:03 ` [PATCH] mips: fix build with O= Sam Ravnborg
2010-05-31 18:03 ` Sam Ravnborg
2010-05-31 18:19 ` Manuel Lauss
2010-05-31 19:00 ` Sam Ravnborg
2010-05-31 22:36 ` Ralf Baechle
2010-05-31 22:46 ` Ralf Baechle
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