From: "H. Peter Anvin" <hpa@zytor.com>
To: Benjamin LaHaise <bcrl@kvack.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Russell King <rmk@arm.linux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86_32: add support for 64 bit __get_user()
Date: Wed, 9 Mar 2016 10:22:50 -0800 [thread overview]
Message-ID: <56E069FA.7070700@zytor.com> (raw)
In-Reply-To: <20160309175016.GO12913@kvack.org>
On 03/09/2016 09:50 AM, Benjamin LaHaise wrote:
> On Wed, Mar 09, 2016 at 09:36:30AM -0800, H. Peter Anvin wrote:
>> On March 9, 2016 9:22:25 AM PST, Benjamin LaHaise <bcrl@kvack.org> wrote:
>>> The existing __get_user() implementation does not support fetching
>>> 64 bit values on 32 bit x86. Implement this in a way that does not
>>> generate any incorrect warnings as cautioned by Russell King. Test
>>> code available at http://www.kvack.org/~bcrl/x86_32-get_user.tar .
> ...
>> Weird. I could swear we had already fixed this a few years ago.
>
> That surprised me as well, but Russell raised the fact that the approaches
> previously tried on 32 bit architectures had caused various incorrect
> compiler warnings for certain obscure cases -- see the code in test_module.c
> in that URL that Russell provided to demonstrate the problem across all the
> corner cases.
Oh, I see... I implemented it for put but not get... weird. You may
want to look at the __inttype() macro defined earlier in this file; it
might be useful.
I presume you have already seen:
>> fs/select.c:710: Error: operand type mismatch for `movq'
>> fs/select.c:714: Error: incorrect register `%cx' used with `q' suffix
fs/select.c:711: Error: operand type mismatch for `movq'
>> fs/select.c:715: Error: incorrect register `%si' used with `q' suffix
--
fs/aio.c: Assembler messages:
>> fs/aio.c:1606: Error: operand type mismatch for `movq'
>> fs/aio.c:1610: Error: incorrect register `%si' used with `q' suffix
... which implies it used 16-bit registers for 64-bit operations when
compiling for 64 bits.
-hpa
next prev parent reply other threads:[~2016-03-09 18:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-09 17:22 [PATCH] x86_32: add support for 64 bit __get_user() Benjamin LaHaise
2016-03-09 17:36 ` H. Peter Anvin
2016-03-09 17:50 ` Benjamin LaHaise
2016-03-09 18:22 ` H. Peter Anvin [this message]
2016-03-09 18:27 ` Benjamin LaHaise
2016-03-09 19:30 ` [PATCH] x86_32: add support for 64 bit __get_user() v2 Benjamin LaHaise
2016-03-09 19:41 ` kbuild test robot
2016-03-09 20:05 ` [PATCH] x86_32: add support for 64 bit __get_user() v3 Benjamin LaHaise
2016-03-14 15:37 ` Benjamin LaHaise
2016-03-14 16:39 ` Ingo Molnar
2016-03-09 20:24 ` [PATCH] x86_32: add support for 64 bit __get_user() v2 kbuild test robot
2016-03-09 18:17 ` [PATCH] x86_32: add support for 64 bit __get_user() kbuild test robot
2016-03-09 18:22 ` kbuild test robot
2016-03-09 18:23 ` kbuild test robot
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