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Re: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex

To: David Daney <david.daney@cavium.com>
Subject: Re: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex
From: Yong Zhang <yong.zhang@windriver.com>
Date: Thu, 18 Aug 2011 10:44:22 +0800
Cc: <linux-mips@linux-mips.org>, <linux-kernel@vger.kernel.org>, Ralf Baechle <ralf@linux-mips.org>
In-reply-to: <4E4BF7C0.80703@cavium.com>
References: <1313546094-11882-1-git-send-email-yong.zhang@windriver.com> <4E4BF7C0.80703@cavium.com>
Reply-to: Yong Zhang <yong.zhang@windriver.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.21 (2010-09-15)
On Wed, Aug 17, 2011 at 10:17:52AM -0700, David Daney wrote:
> >     PTR     compat_sys_sched_setaffinity
> >     PTR     compat_sys_sched_getaffinity    /* 4240 */
> >     PTR     compat_sys_io_setup
> 
> But really I think this patch fixes things at the wrong level.  Each
> architecture potentially needs a similar patch.  What would happen if
> we did something like:

I have thought about it but finally I decide to keep it under arch code;
because sparc64 and s390 have the same issue and they all smooth the
concern by themselves.

For sparc64:
arch/sparc/kernel/sys32.S:
91: SIGN3(sys32_futex, compat_sys_futex, %o1, %o2, %o5)

For s390:
arch/s390/kernel/compat_wrapper.S
ENTRY(compat_sys_futex_wrapper)
        llgtr   %r2,%r2                 # u32 *
        lgfr    %r3,%r3                 # int
        lgfr    %r4,%r4                 # int
        llgtr   %r5,%r5                 # struct compat_timespec *
        llgtr   %r6,%r6                 # u32 *
        lgf     %r0,164(%r15)           # int
        stg     %r0,160(%r15)
        jg      compat_sys_futex        # branch to system call

Maybe we can consolidate all of this like your patch in the future,
but it's a different issue.

Thanks,
Yong

> 
> 
> diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
> index 5f9e689..74ada65 100644
> --- a/kernel/futex_compat.c
> +++ b/kernel/futex_compat.c
> @@ -180,9 +180,9 @@ err_unlock:
>       return ret;
>  }
> 
> -asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
> -             struct compat_timespec __user *utime, u32 __user *uaddr2,
> -             u32 val3)
> +SYSCALL_DEFINE6(compat_sys_futex, u32 __user *, uaddr, int , op, u32, val,
> +             struct compat_timespec __user *, utime, u32 __user *, uaddr2,
> +             u32, val3)
>  {
>       struct timespec ts;
>       ktime_t t, *tp = NULL;
> 
> Obviously the function name is wrong, but a varient of
> SYSCALL_DEFINE*() could be created so the proper function names are
> produced.
> 
> David Daney

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