From: robherring2@gmail.com (Rob Herring)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: implement optimized percpu variable access
Date: Mon, 12 Nov 2012 08:03:48 -0600 [thread overview]
Message-ID: <50A101C4.9090807@gmail.com> (raw)
In-Reply-To: <20121112132811.GF2346@mudshark.cambridge.arm.com>
On 11/12/2012 07:28 AM, Will Deacon wrote:
> On Mon, Nov 12, 2012 at 01:03:12PM +0000, Rob Herring wrote:
>> On 11/12/2012 04:23 AM, Will Deacon wrote:
>>>> +static inline void set_my_cpu_offset(unsigned long off)
>>>> +{
>>>> + asm volatile("mcr p15, 0, %0, c13, c0, 4 @ set TPIDRPRW" : : "r" (off) : "cc" );
>>>> +}
>>>
>>> You don't need the "cc" here.
>>
>> You would think so, but the compiler drops this instruction if you
>> don't. set_cr does the same thing.
>
> Whoa, that sounds suspicious... if the thing is marked volatile GCC
> shouldn't optimise it away if it's reachable. Which toolchain are you
> using?
Ubuntu 12.10 ARM cross compiler:
gcc version 4.7.2 (Ubuntu/Linaro 4.7.2-1ubuntu1)
Rob
next prev parent reply other threads:[~2012-11-12 14:03 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-11 3:20 [PATCH] ARM: implement optimized percpu variable access Rob Herring
2012-11-12 10:23 ` Will Deacon
2012-11-12 13:03 ` Rob Herring
2012-11-12 13:28 ` Will Deacon
2012-11-12 14:03 ` Rob Herring [this message]
2012-11-27 17:29 ` Nicolas Pitre
2012-11-12 14:21 ` Rob Herring
2012-11-12 14:41 ` Will Deacon
2012-11-12 16:51 ` Will Deacon
2012-11-12 21:01 ` Rob Herring
2012-11-13 10:40 ` Will Deacon
2012-11-22 11:34 ` Will Deacon
2012-11-22 11:39 ` Russell King - ARM Linux
2012-11-23 17:06 ` Rob Herring
2012-11-23 17:12 ` Russell King - ARM Linux
2012-11-23 17:16 ` Will Deacon
2012-11-23 20:34 ` Tony Lindgren
2012-11-23 20:32 ` Tony Lindgren
2012-11-25 18:46 ` Rob Herring
2012-11-26 11:13 ` Will Deacon
2012-11-26 15:15 ` Will Deacon
2012-11-26 17:30 ` Rob Herring
2012-11-27 13:17 ` Will Deacon
2012-11-27 13:26 ` Russell King - ARM Linux
2012-11-26 21:58 ` Jamie Lokier
2012-11-26 23:50 ` Jamie Lokier
2012-11-27 1:02 ` Jamie Lokier
2012-11-27 22:02 ` Rob Herring
2012-11-28 12:34 ` Will Deacon
2012-11-27 17:35 ` Nicolas Pitre
2012-11-27 19:27 ` Nicolas Pitre
2012-11-27 17:19 ` Nicolas Pitre
2012-11-27 19:37 ` Rob Herring
2012-11-27 20:42 ` Rob Herring
2012-11-27 22:02 ` Nicolas Pitre
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