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Date: Tue, 8 Feb 2005 17:27:41 -0800
From: Richard Henderson <rth@twiddle.net>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Ingo Molnar <mingo@elte.hu>,
       Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Manfred Spraul <manfred@colorfullife.com>
Subject: Re: out-of-line x86 "put_user()" implementation
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References: <Pine.LNX.4.58.0502062212450.2165@ppc970.osdl.org> <20050207114415.GA22948@elte.hu> <Pine.LNX.4.58.0502071717310.2165@ppc970.osdl.org>
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On Mon, Feb 07, 2005 at 05:20:06PM -0800, Linus Torvalds wrote:
> +#define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=A" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))

This is not constrained enough.  The compiler could choose to put the
return value in edx.  You want

  __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu)
			: "A" ((typeof(*(ptr)))(x)), "c" (ptr))


r~