linux-kernel - Re: [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 current task

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Date:	Thu, 29 Nov 2007 14:25:31 -0800 (PST)
From:	Roland McGrath <roland@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Chuck Ebbert <cebbert@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 current
 task

> But the ones that do the same thing for fs/es/ds are *not*. Those three 
> registers are kernel mode registers (ds/es are the regular kernel data 
> segment, fs is the per-cpu data segment), and restored on return to user 
> space from the stack.

Um, really?  This is x86-64 code.  AIUI those values don't have any effect
at all in 64-bit mode (as the kernel is).  I haven't found any code in
entry_64.S or ia32entry.S that touches them.  __switch_to uses direct
access to the segment registers just as I've done.


Thanks,
Roland
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