From: "H. Peter Anvin" <hpa@zytor.com>
To: Chuck Ebbert <cebbert@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Roland McGrath <roland@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 current task
Date: Thu, 29 Nov 2007 10:23:05 -0800 [thread overview]
Message-ID: <474F0389.5030003@zytor.com> (raw)
In-Reply-To: <474F0243.1020103@redhat.com>
Chuck Ebbert wrote:
> On 11/29/2007 01:09 PM, Linus Torvalds wrote:
>>>> case offsetof(struct user32, regs.gs):
>>>> *val = child->thread.gsindex;
>>>> + if (child == current)
>>>> + asm("movl %%gs,%0" : "=r" (*val));
>>> Won't this return the kernel's GS instead of the user's?
>> No, %gs is untouched by the kernel, so it contains user space version, and
>> getting the value directly from %gs looks correct.
>>
>
> But this is x86_64, where swapgs is done on kernel entry.
>
For i386-x86_64 sharing, getting to the user segments probably should be
macroized. I'm thinking something like
get_user_[cs|ds|es|fs|gs|ss](thread) in <asm/processor.h> doing the
appropriate thing for different configurations.
-hpa
next prev parent reply other threads:[~2007-11-29 18:23 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-29 0:38 [PATCH x86/mm 1/6] x86-64 ia32 ptrace pt_regs cleanup Roland McGrath
2007-11-29 0:40 ` [PATCH x86/mm 2/6] x86-64 ptrace whitespace Roland McGrath
2007-11-29 0:40 ` [PATCH x86/mm 3/6] x86-32 " Roland McGrath
2007-11-29 0:41 ` [PATCH x86/mm 4/6] x86-64 ptrace get/putreg current task Roland McGrath
2007-11-29 17:39 ` Christoph Hellwig
2007-11-29 0:42 ` [PATCH x86/mm 5/6] x86-32 " Roland McGrath
2007-11-29 0:42 ` [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 " Roland McGrath
2007-11-29 17:34 ` Chuck Ebbert
2007-11-29 18:09 ` Linus Torvalds
2007-11-29 18:16 ` H. Peter Anvin
2007-11-29 18:31 ` Linus Torvalds
2007-11-29 18:45 ` H. Peter Anvin
2007-11-29 19:08 ` Linus Torvalds
2007-11-29 19:16 ` H. Peter Anvin
2007-11-29 19:27 ` Andi Kleen
2007-11-29 19:44 ` Ingo Molnar
2007-11-29 20:01 ` H. Peter Anvin
2007-12-01 23:44 ` Jeremy Fitzhardinge
2007-11-29 19:49 ` Linus Torvalds
2007-11-29 20:11 ` Andi Kleen
2007-11-29 20:23 ` Linus Torvalds
2007-11-29 18:17 ` Chuck Ebbert
2007-11-29 18:23 ` H. Peter Anvin [this message]
2007-11-29 22:25 ` Roland McGrath
2007-11-29 22:34 ` Linus Torvalds
2007-11-29 22:21 ` Roland McGrath
2007-11-29 23:00 ` Chuck Ebbert
2007-11-29 10:39 ` [PATCH x86/mm 1/6] x86-64 ia32 ptrace pt_regs cleanup Ingo Molnar
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