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From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	linux-kernel@vger.kernel.org, paulus@samba.org,
	eranian@google.com, robert.richter@amd.com
Subject: Re: [RFC][PATCH 07/11] perf: Provide PERF_SAMPLE_REGS
Date: Thu, 4 Mar 2010 12:04:29 +0100	[thread overview]
Message-ID: <20100304110429.GC21977@elte.hu> (raw)
In-Reply-To: <1267693087.25158.148.camel@laptop>


* Peter Zijlstra <peterz@infradead.org> wrote:

> On Wed, 2010-03-03 at 23:02 +0100, Frederic Weisbecker wrote:
> > On Wed, Mar 03, 2010 at 05:39:43PM +0100, Peter Zijlstra wrote:
> > > Simply copy out the provided pt_regs in a u64 aligned fashion.
> > > 
> > > XXX: do task_pt_regs() and get_irq_regs() always clear everything or
> > >      are we now leaking data?
> > 
> > 
> > It looks like there is a leak in case of non trace syscalls.
> > where we don't appear to save r12-15.
> > 
> > Then task_pt_regs() may leak the top of a process stack...?
> 
> Right, I was afraid of that. I've put this PERF_SAMPLE_REGS thing in the 
> freezer for now as people seem unsure how to deal with it.

Also, we dont want to expose PEBS nor LBR on an ABI level without there being 
a user-space component making good use of it.

For example tools/perf/ support would qualify. Raw libraries alone dont really 
count as they generally lag plus there's no guarantee for a full feedback loop 
either.

Adding ABI details is always a tricky business and we only want to do it if 
there's direct, immediate, close involvement with the user-space side, and 
real, immediate benefits to users.

Thanks,

	Ingo

  reply	other threads:[~2010-03-04 17:08 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-03 16:39 [RFC][PATCH 00/11] Another stab at PEBS and LBR support Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 01/11] perf, x86: Remove superfluous arguments to x86_perf_event_set_period() Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 02/11] perf, x86: Remove superfluous arguments to x86_perf_event_update() Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 03/11] perf, x86: Change x86_pmu.{enable,disable} calling convention Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 04/11] perf, x86: Use unlocked bitops Peter Zijlstra
2010-03-03 16:39 ` [RFC][PATCH 05/11] perf: Generic perf_sample_data initialization Peter Zijlstra
2010-03-03 16:49   ` David Miller
2010-03-03 21:14   ` Frederic Weisbecker
2010-03-05  8:44   ` Jean Pihet
2010-03-03 16:39 ` [RFC][PATCH 06/11] perf, x86: PEBS infrastructure Peter Zijlstra
2010-03-03 17:38   ` Robert Richter
2010-03-03 17:42     ` Peter Zijlstra
2010-03-04  8:50       ` Robert Richter
2010-03-03 16:39 ` [RFC][PATCH 07/11] perf: Provide PERF_SAMPLE_REGS Peter Zijlstra
2010-03-03 17:30   ` Stephane Eranian
2010-03-03 17:39     ` Peter Zijlstra
2010-03-03 17:49       ` Stephane Eranian
2010-03-03 17:55         ` David Miller
2010-03-03 18:18           ` Stephane Eranian
2010-03-03 19:18           ` Peter Zijlstra
2010-03-04  2:59           ` Ingo Molnar
2010-03-04 12:58             ` Arnaldo Carvalho de Melo
2010-03-03 22:02   ` Frederic Weisbecker
2010-03-04  8:58     ` Peter Zijlstra
2010-03-04 11:04       ` Ingo Molnar [this message]
2010-03-03 16:39 ` [RFC][PATCH 08/11] perf, x86: Implement simple LBR support Peter Zijlstra
2010-03-03 21:52   ` Stephane Eranian
2010-03-04  8:58     ` Peter Zijlstra
2010-03-03 21:57   ` Stephane Eranian
2010-03-04  8:58     ` Peter Zijlstra
2010-03-04 17:54       ` Stephane Eranian
2010-03-04 18:18         ` Peter Zijlstra
2010-03-04 20:23           ` Peter Zijlstra
2010-03-04 20:57             ` Stephane Eranian
2010-03-03 16:39 ` [RFC][PATCH 09/11] perf, x86: Implement PERF_SAMPLE_BRANCH_STACK Peter Zijlstra
2010-03-03 21:08   ` Frederic Weisbecker
2010-03-03 16:39 ` [RFC][PATCH 10/11] perf, x86: use LBR for PEBS IP+1 fixup Peter Zijlstra
2010-03-03 18:05   ` Masami Hiramatsu
2010-03-03 19:37     ` Peter Zijlstra
2010-03-03 21:11       ` Masami Hiramatsu
2010-03-03 21:50         ` Stephane Eranian
2010-03-04  8:57           ` Peter Zijlstra
2010-03-09  1:41             ` Stephane Eranian
2010-03-03 16:39 ` [RFC][PATCH 11/11] perf, x86: Clean up IA32_PERF_CAPABILITIES usage Peter Zijlstra

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