From: David Laight <David.Laight@ACULAB.COM>
To: 'Arnd Bergmann' <arnd@arndb.de>
Cc: Greg KH <gregkh@linuxfoundation.org>,
David Hildenbrand <david@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Nick Desaulniers <ndesaulniers@google.com>,
Christoph Hellwig <hch@lst.de>,
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Andrew Morton <akpm@linux-foundation.org>,
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Subject: RE: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c"
Date: Fri, 23 Oct 2020 13:28:57 +0000 [thread overview]
Message-ID: <8e758668cffa4713969df33299180c64@AcuMS.aculab.com> (raw)
In-Reply-To: <CAK8P3a1n+b8hOMhNQSDzgic03dyXbmpccfTJ3C1bGKvzsgMXbg@mail.gmail.com>
From: Arnd Bergmann
> Sent: 23 October 2020 14:23
>
> On Fri, Oct 23, 2020 at 2:46 PM David Laight <David.Laight@aculab.com> wrote:
> >
> > From: Greg KH <gregkh@linuxfoundation.org>
> > > Sent: 22 October 2020 14:51
> >
> > I've rammed the code into godbolt.
> >
> > https://godbolt.org/z/9v5PPW
> >
> > Definitely a clang bug.
> >
> > Search for [wx]24 in the clang output.
> > nr_segs comes in as w2 and the initial bound checks are done on w2.
> > w24 is loaded from w2 - I don't believe this changes the high bits.
>
> You believe wrong, "mov w24, w2" is a zero-extending operation.
Ah ok, but gcc uses utxw for the same task.
I guess they could be the same opcode.
Last time I wrote ARM thumb didn't really exist - never mind 64bit
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-10-23 13:29 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-25 4:51 let import_iovec deal with compat_iovecs as well v4 Christoph Hellwig
2020-09-25 4:51 ` [PATCH 1/9] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-25 4:51 ` [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c Christoph Hellwig
2020-10-21 16:13 ` Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Greg KH
2020-10-21 20:59 ` David Laight
2020-10-21 23:39 ` Al Viro
2020-10-22 8:26 ` Greg KH
2020-10-22 8:35 ` David Hildenbrand
2020-10-22 8:40 ` David Laight
2020-10-22 8:48 ` David Hildenbrand
2020-10-22 9:01 ` Greg KH
2020-10-22 9:06 ` David Laight
2020-10-22 9:19 ` David Hildenbrand
2020-10-22 9:25 ` David Hildenbrand
2020-10-22 9:32 ` David Laight
2020-10-22 9:36 ` David Hildenbrand
2020-10-22 10:48 ` Greg KH
2020-10-22 12:18 ` Greg KH
2020-10-22 12:42 ` David Hildenbrand
2020-10-22 12:57 ` Greg KH
2020-10-22 13:50 ` Greg KH
[not found] ` <CAK8P3a1B7OVdyzW0-97JwzZiwp0D0fnSfyete16QTvPp_1m07A@mail.gmail.com>
2020-10-22 14:40 ` Greg KH
2020-10-22 16:15 ` David Laight
2020-10-23 12:46 ` David Laight
2020-10-23 13:09 ` David Hildenbrand
2020-10-23 14:33 ` David Hildenbrand
2020-10-23 14:39 ` David Laight
2020-10-23 14:47 ` 'Greg KH'
2020-10-23 16:33 ` David Hildenbrand
2020-11-02 9:06 ` David Laight
2020-11-02 13:52 ` 'Greg KH'
2020-11-02 18:23 ` David Laight
2020-10-23 17:58 ` Al Viro
2020-10-23 18:27 ` Segher Boessenkool
2020-10-23 21:28 ` David Laight
2020-10-24 17:29 ` Segher Boessenkool
2020-10-24 21:12 ` David Laight
[not found] ` <CAK8P3a1n+b8hOMhNQSDzgic03dyXbmpccfTJ3C1bGKvzsgMXbg@mail.gmail.com>
2020-10-23 13:28 ` David Laight [this message]
2020-10-22 13:23 ` Christoph Hellwig
2020-10-22 16:35 ` David Laight
2020-10-22 16:40 ` Matthew Wilcox
2020-10-22 16:50 ` David Laight
2020-10-22 17:00 ` Nick Desaulniers
2020-10-22 20:59 ` Eric Biggers
2020-10-22 21:28 ` Al Viro
2020-10-22 18:19 ` Al Viro
2020-10-22 17:54 ` Nick Desaulniers
[not found] ` <CAK8P3a3LjG+ZvmQrkb9zpgov8xBkQQWrkHBPgjfYSqBKGrwT4w@mail.gmail.com>
2020-10-22 19:04 ` Nick Desaulniers
2020-10-22 19:24 ` Al Viro
2020-10-22 19:27 ` Al Viro
2020-10-22 20:06 ` Al Viro
2020-10-22 20:09 ` Al Viro
2020-10-22 20:11 ` Nick Desaulniers
2020-10-22 22:07 ` David Laight
2020-10-23 13:12 ` David Hildenbrand
2020-10-22 22:04 ` David Laight
2020-10-22 9:28 ` David Laight
2020-10-22 9:02 ` David Laight
2020-09-25 4:51 ` [PATCH 3/9] iov_iter: refactor rw_copy_check_uvector and import_iovec Christoph Hellwig
2020-09-25 4:51 ` [PATCH 4/9] iov_iter: transparently handle compat iovecs in import_iovec Christoph Hellwig
2020-09-25 4:51 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-25 4:51 ` [PATCH 6/9] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-25 4:51 ` [PATCH 7/9] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-25 4:51 ` [PATCH 8/9] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-25 4:51 ` [PATCH 9/9] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
2020-09-25 15:23 ` let import_iovec deal with compat_iovecs as well v4 Al Viro
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