From: Vince Weaver <vincent.weaver@maine.edu>
Date: Mon, 30 Dec 2013 20:39:45 +0000 (-0500)
Subject: perf list: Fix checking for supported events on older kernels
X-Git-Tag: v3.14-rc4~11^2^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=88fee52e58ca14d8465b614774ed0bf08e1a7790;p=pandora-kernel.git

perf list: Fix checking for supported events on older kernels

"perf list" listing of hardware events doesn't work on older ARM devices.
The change enabling event detection:

 commit b41f1cec91c37eeea6fdb15effbfa24ea0a5536b
 Author: Namhyung Kim <namhyung.kim@lge.com>
 Date:   Tue Aug 27 11:41:53 2013 +0900

     perf list: Skip unsupported events

uses the following code in tools/perf/util/parse-events.c:

        struct perf_event_attr attr = {
                .type = type,
                .config = config,
                .disabled = 1,
                .exclude_kernel = 1,
        };

On ARM machines pre-dating the Cortex-A15 this doesn't work, as these
machines don't support .exclude_kernel.  So starting with 3.12 "perf
list" does not report any hardware events at all on older machines (seen
on Rasp-Pi, Pandaboard, Beagleboard, etc).

This version of the patch makes changes suggested by Namhyung Kim to
check for EACCESS and retry (instead of just dropping the
exclude_kernel) so we can properly handle machines where
/proc/sys/kernel/perf_event_paranoid is set to 2.

Reported-by: Chad Paradis <chad.paradis@umit.maine.edu>
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Chad Paradis <chad.paradis@umit.maine.edu>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1312301536150.28814@vincent-weaver-1.um.maine.edu
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

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