From: Russell King - ARM Linux <linux@arm•linux.org.uk>
To: Benjamin LaHaise <bcrl@kvack•org>
Cc: Stephen Rothwell <sfr@canb•auug.org.au>,
Geert Uytterhoeven <geert@linux-m68k•org>,
Linux-Next <linux-next@vger•kernel.org>,
"linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>,
"linux-arm-kernel@lists•infradead.org"
<linux-arm-kernel@lists•infradead.org>
Subject: Re: linux-next: build failure after merge of the aio tree
Date: Thu, 4 Feb 2016 14:39:07 +0000 [thread overview]
Message-ID: <20160204143907.GG10826@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20160204143204.GC16315@kvack.org>
On Thu, Feb 04, 2016 at 09:32:04AM -0500, Benjamin LaHaise wrote:
> On Thu, Feb 04, 2016 at 02:12:53PM +0000, Russell King - ARM Linux wrote:
> > Hence, __get_user() on x86-32 with a 64-bit quantity results in
> > __get_user_bad() being called, which is an undefined function.
> > Only if you build with x86-64 support enabled (iow, CONFIG_X86_32 not
> > defined) then you get the 64-bit __get_user() support.
> >
> > Given this, I fail to see how x86-32 can possibly work.
>
> You're right; mea culpa. It compiles without warning on x86-32, but it
> does not link. I still think this is broken archtecture stupidity since
> put_user() works for 64 bit data types.
Indeed, and you'll find that several other architectures besides ARM and
x86-32 have exactly the same problem - as I listed in my message from a
few days ago.
Okay, so now I get to set you a challenge, since you're the one wanting
64-bit __get_user(): try implementing it on x86-32 :)
Also in my previous message from a few days ago I provided a set of
functions which test out the implementation. Here they are... again.
All these should not produce any warnings, and should produce correct
code - especially the narrowing/widening tests:
int test_8(unsigned char *v, unsigned char *p)
{ return __get_user(*v, p); }
int test_8_constp(unsigned char *v, const unsigned char *p)
{ return __get_user(*v, p); }
int test_8_volatilep(unsigned char *v, volatile unsigned char *p)
{ return __get_user(*v, p); }
int test_16(unsigned short *v, unsigned short *p)
{ return __get_user(*v, p); }
int test_16_constp(unsigned short *v, const unsigned short *p)
{ return __get_user(*v, p); }
int test_32(unsigned int *v, unsigned int *p)
{ return __get_user(*v, p); }
int test_32_constp(unsigned int *v, const unsigned int *p)
{ return __get_user(*v, p); }
int test_64(unsigned long long *v, unsigned long long *p)
{ return __get_user(*v, p); }
int test_64_constp(unsigned long long *v, const unsigned long long *p)
{ return __get_user(*v, p); }
int test_ptr(unsigned int **v, unsigned int **p)
{ return __get_user(*v, p); }
int test_const(unsigned int *v, const unsigned int *p)
{ return __get_user(*v, p); }
int test_64_narrow(unsigned long *v, unsigned long long *p)
{ return __get_user(*v, p); }
int test_32_wide(unsigned long long *v, unsigned long *p)
{ return __get_user(*v, p); }
However, this one should warn:
int test_wrong(char **v, const char **p)
{ return __get_user(*v, p); }
Good luck (I think you'll need lots of it to get a working solution)! :)
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2016-02-04 14:39 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-12 5:40 linux-next: build failure after merge of the aio tree Stephen Rothwell
2016-01-12 16:38 ` Benjamin LaHaise
2016-01-27 2:40 ` Stephen Rothwell
2016-01-29 11:30 ` Russell King - ARM Linux
2016-01-29 12:03 ` Geert Uytterhoeven
2016-02-04 2:19 ` Stephen Rothwell
2016-02-04 13:41 ` Benjamin LaHaise
2016-02-04 13:50 ` Russell King - ARM Linux
2016-02-04 14:08 ` Benjamin LaHaise
2016-02-04 14:12 ` Russell King - ARM Linux
2016-02-04 14:32 ` Benjamin LaHaise
2016-02-04 14:39 ` Russell King - ARM Linux [this message]
2016-02-04 16:01 ` Benjamin LaHaise
2016-02-04 16:17 ` Russell King - ARM Linux
2016-02-04 16:27 ` Benjamin LaHaise
2016-02-04 16:47 ` Benjamin LaHaise
2016-02-04 18:48 ` Benjamin LaHaise
2016-01-15 2:24 ` Stephen Rothwell
2016-01-15 7:39 ` Christoph Hellwig
2016-01-15 9:23 ` Stephen Rothwell
2016-01-15 9:25 ` Christoph Hellwig
2016-01-15 15:18 ` Benjamin LaHaise
2016-01-15 22:55 ` Stephen Rothwell
2016-03-14 4:49 ` Stephen Rothwell
2016-03-14 17:08 ` Benjamin LaHaise
2016-03-14 20:41 ` Stephen Rothwell
-- strict thread matches above, loose matches on Subject: below --
2016-03-15 6:46 Stephen Rothwell
2016-03-15 14:38 ` Andy Shevchenko
2016-03-15 16:42 ` Arnd Bergmann
2016-03-15 16:19 ` Sudip Mukherjee
2016-03-15 16:22 ` Benjamin LaHaise
2016-03-15 22:02 ` Arnd Bergmann
2016-03-16 11:12 ` Andy Shevchenko
2016-03-16 13:59 ` Arnd Bergmann
2016-03-16 14:07 ` Benjamin LaHaise
2013-08-30 7:55 Stephen Rothwell
2013-08-30 14:26 ` Benjamin LaHaise
2013-08-30 17:38 ` Linus Torvalds
2013-08-30 17:42 ` Benjamin LaHaise
2013-08-21 7:45 Stephen Rothwell
2013-08-21 15:52 ` Dave Kleikamp
2013-08-21 23:53 ` Stephen Rothwell
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