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From: Yong Zhang <yong.zhang@windriver.com>
To: David Daney <david.daney@cavium.com>
Cc: <linux-mips@linux-mips.org>, <linux-kernel@vger.kernel.org>,
	Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex
Date: Thu, 18 Aug 2011 10:32:47 +0800	[thread overview]
Message-ID: <20110818023247.GA3750@windriver.com> (raw)
In-Reply-To: <4E4BF7C0.80703@cavium.com>

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;
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).

Thanks,
Yong

  reply	other threads:[~2011-08-18  2:33 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-17  1:54 [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex Yong Zhang
2011-08-17 12:43 ` Ralf Baechle
2011-08-17 17:17 ` David Daney
2011-08-18  2:32   ` Yong Zhang [this message]
2011-08-18 16:23     ` David Daney
2011-08-19  1:56       ` Yong Zhang
2011-08-18  2:44   ` Yong Zhang
2011-08-18 20:19   ` Ralf Baechle
2011-08-19  3:49     ` How to trace compat syscalls? [Was Re: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex] Yong Zhang
2011-08-19  4:15       ` Yong Zhang

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