linux-kernel - Re: perf_counters: page fault trace record

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 13 Jun 2009 19:17:57 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: perf_counters: page fault trace record

Corey Ashford writes:

> Paul Mackerras wrote:
> > Can't you do what you need just using a page fault software counter
> > with sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR and
> > sample_period = 1?
> 
> I thought about that, but I was under the (incorrect?) impression that 
> on Power, the PERF_SAMPLE_ADDR would be set by the value of the SDAR 
> register, which wouldn't be correct for the case of a page fault.

No, the PERF_SAMPLE_ADDR value only comes from SDAR for a hardware
counter overflow event.  For the page-fault software counter the
PERF_SAMPLE_ADDR value will always be the faulting address.

Paul.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/