From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Linux Next Mailing List <linux-next@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@suse.de>
Subject: Re: linux-next: build failure after merge of the vfs tree
Date: Mon, 28 Sep 2020 23:10:56 -0500 [thread overview]
Message-ID: <20200929041056.uj6gedgm6hfjaxrx@treble> (raw)
In-Reply-To: <20200925133820.GW3421308@ZenIV.linux.org.uk>
On Fri, Sep 25, 2020 at 02:38:20PM +0100, Al Viro wrote:
> On Fri, Sep 25, 2020 at 10:01:28PM +1000, Stephen Rothwell wrote:
> > $ x86_64-linux-gnu-gcc --version
> > x86_64-linux-gnu-gcc (Debian 10.2.0-9) 10.2.0
> > $ x86_64-linux-gnu-ld --version
> > GNU ld (GNU Binutils for Debian) 2.35
> >
> > and the gcc plugins don't get built for the allnoconfig builds.
>
> > I reverted my Revert commit after I finished linux-next today and built
> > the x86_64 allnoconfig verion of lib/iov_iter.s:
> >
> > $ grep -A 1 '41 "/home/sfr/next/next/arch/x86/include/asm/barrier.h"' lib/iov_iter.s
> > # 41 "/home/sfr/next/next/arch/x86/include/asm/barrier.h" 1
> > cmp $140737488351232,%rdx; sbb %rcx,%rcx; #, uaddr, mask
>
> Wait a sec...
> static inline unsigned long array_index_mask_nospec(unsigned long index,
> unsigned long size)
> {
> unsigned long mask;
>
> asm volatile ("cmp %1,%2; sbb %0,%0;"
> :"=r" (mask)
> :"g"(size),"r" (index)
> :"cc");
> return mask;
> }
>
> used with large constant size will blow up - "g" is wrong, since cmp allows
> 64bit arguments to be register or memory ones; immediates can't go past
> 32bit.
>
> Looks like on the configs where it builds we end up with not seeing it's
> a constant...
>
> Josh, any ideas? We could, of course, make it "r"(size), but that would
> be unpleasant in all existing callers...
Sorry, I've been traveling. I'd just vote for making it "r".
array_index_nospec() is always called after a usercopy. I don't think
anyone will notice the extra mov, for the cases where it would be
propagated as an immediate. And the argument *is* an unsigned long
after all.
Stephen, can you confirm this fixes it?
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index d158ea1fa250..69045ac62f58 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -40,7 +40,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
asm volatile ("cmp %1,%2; sbb %0,%0;"
:"=r" (mask)
- :"g"(size),"r" (index)
+ :"r"(size), "r"(index)
:"cc");
return mask;
}
next prev parent reply other threads:[~2020-09-29 4:11 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 8:30 linux-next: build failure after merge of the vfs tree Stephen Rothwell
2020-09-24 20:08 ` Al Viro
2020-09-25 12:01 ` Stephen Rothwell
2020-09-25 13:38 ` Al Viro
2020-09-29 4:10 ` Josh Poimboeuf [this message]
2020-10-06 14:30 ` Josh Poimboeuf
2020-10-06 21:04 ` Stephen Rothwell
2020-10-07 15:46 ` Josh Poimboeuf
-- strict thread matches above, loose matches on Subject: below --
2021-01-04 22:36 Stephen Rothwell
2021-01-04 23:28 ` Al Viro
2020-10-27 4:14 Stephen Rothwell
2020-10-27 4:59 ` Al Viro
2020-11-10 19:00 ` Al Viro
2020-11-10 21:24 ` Stephen Rothwell
2020-09-28 1:31 Stephen Rothwell
2020-09-28 6:05 ` Christoph Hellwig
2020-07-29 1:56 Stephen Rothwell
2020-07-29 6:33 ` Christoph Hellwig
2020-07-29 19:19 ` Al Viro
2020-07-27 12:06 Stephen Rothwell
2020-05-07 0:39 Stephen Rothwell
2020-05-07 2:35 ` Al Viro
2020-05-07 15:07 ` Jens Axboe
2020-01-10 6:57 Stephen Rothwell
2020-01-10 10:00 ` Carlos Maiolino
2020-01-10 11:03 ` Carlos Maiolino
2020-01-10 22:44 ` Stephen Rothwell
2020-01-13 9:28 ` Carlos Maiolino
2020-01-24 2:41 ` Stephen Rothwell
2020-01-29 22:40 ` Stephen Rothwell
2019-01-02 4:01 Stephen Rothwell
2019-01-30 3:45 ` Stephen Rothwell
2018-10-03 0:32 Stephen Rothwell
2018-10-16 0:17 ` Stephen Rothwell
2018-10-16 16:37 ` Jaegeuk Kim
2018-10-16 20:45 ` Stephen Rothwell
2018-09-10 3:59 Stephen Rothwell
2018-09-10 3:35 Stephen Rothwell
2018-09-18 21:38 ` Stephen Rothwell
2018-09-18 22:17 ` David Howells
2018-09-18 23:49 ` Stephen Rothwell
2018-09-19 7:17 ` Geert Uytterhoeven
2018-09-19 6:01 ` David Howells
2018-09-19 6:31 ` Stephen Rothwell
2018-09-20 10:48 ` Michael Ellerman
2018-09-20 16:20 ` David Howells
2018-09-20 10:44 ` Michael Ellerman
2018-10-29 4:33 ` Stephen Rothwell
2018-10-29 9:07 ` Stephen Rothwell
2018-10-29 9:21 ` David Howells
2018-10-29 10:29 ` Stephen Rothwell
2018-09-06 2:28 Stephen Rothwell
2018-08-07 10:58 Stephen Rothwell
2018-08-07 1:11 Stephen Rothwell
2018-08-06 0:37 Stephen Rothwell
2018-08-06 12:24 ` Stephen Rothwell
2018-08-07 0:59 ` Stephen Rothwell
2018-08-07 2:20 ` Masahiro Yamada
2018-06-19 1:47 Stephen Rothwell
2018-03-19 6:06 Stephen Rothwell
2018-03-19 19:56 ` Mateusz Guzik
2018-04-03 2:26 ` Stephen Rothwell
2018-04-08 2:19 ` Al Viro
2018-04-08 2:55 ` Stephen Rothwell
2017-12-03 23:16 Stephen Rothwell
2017-07-11 0:55 Stephen Rothwell
2017-07-11 9:21 ` David Howells
2017-07-10 2:15 Stephen Rothwell
2017-07-10 2:34 ` Al Viro
2017-02-27 0:27 Stephen Rothwell
2017-02-27 8:31 ` David Howells
2016-07-29 1:19 Stephen Rothwell
2016-07-29 4:18 ` Al Viro
2016-05-02 1:25 Stephen Rothwell
2016-05-02 1:31 ` Al Viro
2016-05-02 4:48 ` Abhijith Das
2015-12-10 0:18 Stephen Rothwell
2015-12-10 0:23 ` Stephen Rothwell
2015-12-10 0:48 ` Al Viro
2015-12-10 15:44 ` Mike Marshall
2015-12-21 0:23 ` Stephen Rothwell
2016-01-07 0:42 ` Stephen Rothwell
2016-01-07 2:09 ` Al Viro
2015-12-09 5:58 Stephen Rothwell
2015-12-09 1:19 Stephen Rothwell
2015-12-09 21:30 ` Mike Marshall
2015-12-09 22:20 ` Stephen Rothwell
2015-12-09 22:53 ` Andreas Grünbacher
2015-12-07 22:42 Stephen Rothwell
2015-05-11 1:26 Stephen Rothwell
2015-05-13 2:26 ` Stephen Rothwell
2015-03-13 1:02 Stephen Rothwell
2015-03-24 3:24 ` Stephen Rothwell
2015-03-24 10:44 ` Christoph Hellwig
2014-12-10 7:45 Stephen Rothwell
2014-12-11 2:32 ` Al Viro
2014-04-22 1:26 Stephen Rothwell
2014-04-23 0:33 ` Stephen Rothwell
2013-11-07 0:30 Stephen Rothwell
2013-09-09 2:33 Stephen Rothwell
2013-09-09 8:54 ` Ian Kent
2013-06-24 1:35 Stephen Rothwell
2013-06-24 9:34 ` Al Viro
2013-05-01 2:22 Stephen Rothwell
2013-05-01 13:13 ` J. Bruce Fields
2013-04-08 1:15 Stephen Rothwell
2013-04-09 15:49 ` Stephen Rothwell
2013-04-03 0:22 Stephen Rothwell
2013-04-03 1:14 ` Al Viro
2013-04-02 0:26 Stephen Rothwell
2013-04-02 0:39 ` Al Viro
2012-07-16 0:59 Stephen Rothwell
2012-05-31 0:51 Stephen Rothwell
2012-05-31 1:02 ` Al Viro
2012-01-03 1:43 Stephen Rothwell
2012-01-03 13:39 ` Jan Kara
2011-12-22 0:15 Stephen Rothwell
2011-12-20 0:31 Stephen Rothwell
2011-12-19 1:06 Stephen Rothwell
2011-12-19 1:12 ` Al Viro
2011-07-16 6:44 Stephen Rothwell
2011-07-25 3:20 ` Stephen Rothwell
2011-07-25 18:26 ` Trond Myklebust
2011-07-16 6:36 Stephen Rothwell
2010-07-19 0:25 Stephen Rothwell
[not found] ` <20100719102520.a2d4f103.sfr-3FnU+UHB4dNDw9hX6IcOSA@public.gmane.org>
2010-08-04 1:47 ` Stephen Rothwell
2010-07-12 2:24 Stephen Rothwell
2010-07-12 5:31 ` Ryusuke Konishi
2010-06-22 1:22 Stephen Rothwell
2010-08-04 1:50 ` Stephen Rothwell
2010-05-28 1:45 Stephen Rothwell
2010-05-28 1:51 ` Al Viro
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