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SubjectRe: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex
On 08/17/2011 07:32 PM, Yong Zhang wrote:
> On Wed, Aug 17, 2011 at 10:17:52AM -0700, David Daney wrote:
>>> diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
>>> index 46c4763..f48b18e 100644
>>> --- a/arch/mips/kernel/scall64-o32.S
>>> +++ b/arch/mips/kernel/scall64-o32.S
>>> @@ -441,7 +441,7 @@ sys_call_table:
>>> PTR sys_fremovexattr /* 4235 */
>>> PTR sys_tkill
>>> PTR sys_sendfile64
>>> - PTR compat_sys_futex
>>> + PTR sys_32_futex
>>
>> This change is redundant, scall64-o32.S already does the right thing
>
> My first virsion(not sent out) doesn't include scall64-o32.S either.
>
>> so additional zero extending is not needed and is just extra
>> instructions to execute for no reason.
>
> Why I'm adding it here is for:
> 1)code consistent, otherwise we must move SYSCALL_DEFINE6(32_futex,...)
> under CONFIG_MIPS32_N32;

No, you don't have to move it. Just don't call it.


> 2)I'm afraid there may be some other way to touch the high 32-bit of a
> register, so touching scall64-o32.S is also for safety(due to unknown
> reason, fix me if I'm wrong).

OK: You are mistaken. You claim you don't understand what the code
does. That is really a poor justification for modifying it.

David Daney


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