From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
hpa@zytor.com, 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>
Subject: Re: [tip:perf/core] perf/x86: Fix USER/KERNEL tagging of samples
Date: Tue, 10 Jul 2012 11:48:45 +0200 [thread overview]
Message-ID: <20120710094845.GB14821@gmail.com> (raw)
In-Reply-To: <1341910954.3462.102.camel@twins>
* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> On Mon, 2012-07-09 at 10:55 -0700, Linus Torvalds wrote:
> > However, it is worth pointing out that sp/bp have exactly the same
> > segment base issue. So if you do stack tracing into user mode, you
> > should really do the same thing for those. And quite frankly, at that
> > point vm86 mode and the stack segment matters in other ways than just
> > the base pointer: a 16-bit stack segment acts fundamentally
> > differently from a 32-bit one. So at that point it may well make much
> > more sense to take the approach Ingo suggests, and simply not follow
> > stack frames at all.
>
> Right, so I amended the patch to ignore vm86 stacks and added
> {cs,ss}_base magic to ia32 stacks.
>
> Ingo, do you want me to do a version where I simply bail on
> everything if regs->{cs,ss} != {__USER_CS, __USER32_CS} ||
> regs->flags & VM ?
Only if it's really simple to do - out of morbid curiosity, to
compare the two diffstats and such.
Thanks,
Ingo
next prev parent reply other threads:[~2012-07-10 9:48 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 [this message]
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
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