linux-kernel - Re: vm86.c audit_syscall_exit() call trashes registers

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Date:	Fri, 28 Sep 2007 23:09:35 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	William Cattey <wdc@....EDU>
CC:	Andi Kleen <andi@...stfloor.org>, Chuck Anderson <cra@....EDU>,
	linux-kernel@...r.kernel.org
Subject: Re: vm86.c audit_syscall_exit() call trashes registers

Jeremy Fitzhardinge wrote:
> @@ -306,19 +334,18 @@ static void do_sys_vm86(struct kernel_vm
>         tsk->thread.screen_bitmap = info->screen_bitmap;
>         if (info->flags & VM86_SCREEN_BITMAP)
>                 mark_screen_rdonly(tsk->mm);
>         __asm__ __volatile__("xorl %eax,%eax; movl %eax,%fs; movl %eax,%gs\n\t");
>   

Oh, this line is also clearly bogus, since it clobbers %eax without
telling the compiler.  The minimal change would be something like:

	asm volatile("mov %0, %%fs; mov %0, %%gs" : : "r" (0));


    J
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