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Date: Sun, 21 Aug 2011 15:51:26 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>, mingo@redhat.com,
        Richard Weinberger <richard@nod.at>,
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        linux-kernel@vger.kernel.org
Subject: Re: SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird
 crap with vdso on uml/i386)
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On Sun, Aug 21, 2011 at 09:37:18AM -0400, Andrew Lutomirski wrote:

> Gack.  Is this a holdover from the 32-bit code that shares the
> argument save area with the parameters passed on the C stack?  If so,
> we could just set up the argument save area honestly and pass the real
> parameters in registers like 64-bit C code expects.
> 
> If the tracing and restart cases use iret to return to userspace, this
> should all just work.  ptrace users shouldn't notice the overhead, and
> syscall restart is presumably slow enough anyway that it wouldn't
> matter.  The userspace entry code would be as simple as:
> 
> sysenter
> ret
> 
> or
> 
> sysexit
> ret

You are making no sense at all...