From: "H. Peter Anvin" <hpa@zytor.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Linus Torvalds <torvalds@linux-foundation.org>,
eranian@google.com, linux-kernel@vger.kernel.org,
fweisbec@gmail.com, akpm@linux-foundation.org,
tglx@linutronix.de, linux-tip-commits@vger.kernel.org,
Robert Richter <robert.richter@amd.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [tip:perf/core] perf/x86: Fix USER/KERNEL tagging of samples
Date: Tue, 31 Jul 2012 11:11:40 -0700 [thread overview]
Message-ID: <50181FDC.4030200@zytor.com> (raw)
In-Reply-To: <20120710094803.GA14821@gmail.com>
On 07/10/2012 02:48 AM, Ingo Molnar wrote:
>
> We could read out the current GDT [the SGDT instruction] instead
> of looking at gdt_page.
>
> Then we'd have to decode that descriptor, the limit. Decide
> whether the selector points to the GDT or LDT. All the fun x86
> legacies that we mostly forgot already after two decades of
> running the kernel in flat linear mode...
>
In 32-bit mode there are actually instructions that do that work for you.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
prev parent reply other threads:[~2012-07-31 18:13 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-06 6:20 [tip:perf/core] perf/x86: Fix USER/KERNEL tagging of samples tip-bot for Peter Zijlstra
2012-07-06 16:29 ` Linus Torvalds
2012-07-06 18:12 ` Peter Zijlstra
2012-07-06 18:16 ` Linus Torvalds
2012-07-06 18:34 ` Linus Torvalds
2012-07-06 20:48 ` Peter Zijlstra
2012-07-06 20:59 ` Linus Torvalds
2012-07-09 11:23 ` Peter Zijlstra
2012-07-09 17:55 ` Linus Torvalds
2012-07-10 9:02 ` Peter Zijlstra
2012-07-10 9:48 ` Ingo Molnar
2012-07-10 9:50 ` Peter Zijlstra
2012-07-10 9:52 ` Peter Zijlstra
2012-07-10 9:55 ` Ingo Molnar
2012-07-31 17:57 ` [tip:perf/urgent] perf/x86: Fix USER/ KERNEL tagging of samples properly tip-bot for Peter Zijlstra
2012-07-09 18:41 ` [tip:perf/core] perf/x86: Fix USER/KERNEL tagging of samples Ingo Molnar
2012-07-10 7:54 ` Peter Zijlstra
2012-07-10 8:02 ` Ingo Molnar
2012-07-10 8:21 ` Ingo Molnar
2012-07-10 8:52 ` Peter Zijlstra
2012-07-10 9:48 ` Ingo Molnar
2012-07-31 18:11 ` H. Peter Anvin [this message]
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