lkml.org 
[lkml]   [2009]   [Aug]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:perfcounters/urgent] perf_counter/powerpc: Avoid oops on cpus without perf_counter hardware support
Commit-ID:  e136499a084c0b921dd0c7a338e4454be158d9f9
Gitweb: http://git.kernel.org/tip/e136499a084c0b921dd0c7a338e4454be158d9f9
Author: Paul Mackerras <paulus@samba.org>
AuthorDate: Fri, 7 Aug 2009 16:59:45 +1000
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 7 Aug 2009 10:29:16 +0200

perf_counter/powerpc: Avoid oops on cpus without perf_counter hardware support

If we have the powerpc perf_counter backend compiled in, but
the cpu we are running on is one where we don't support the
PMU, we currently oops in hw_perf_group_sched_in if we try to
use any counters, because ppmu is NULL in that case, and we
unconditionally dereference ppmu.

This fixes the problem by adding a check if ppmu is NULL at the
beginning of hw_perf_group_sched_in, and also at the beginning
of the other functions that get called from the perf_counter
core, i.e. hw_perf_disable, hw_perf_enable, and
hw_perf_counter_setup.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: benh@kernel.crashing.org
LKML-Reference: <19067.53473.239250.278692@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
arch/powerpc/kernel/perf_counter.c | 8 ++++++++
1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c
index 809fdf9..70e1f57 100644
--- a/arch/powerpc/kernel/perf_counter.c
+++ b/arch/powerpc/kernel/perf_counter.c
@@ -518,6 +518,8 @@ void hw_perf_disable(void)
struct cpu_hw_counters *cpuhw;
unsigned long flags;

+ if (!ppmu)
+ return;
local_irq_save(flags);
cpuhw = &__get_cpu_var(cpu_hw_counters);

@@ -572,6 +574,8 @@ void hw_perf_enable(void)
int n_lim;
int idx;

+ if (!ppmu)
+ return;
local_irq_save(flags);
cpuhw = &__get_cpu_var(cpu_hw_counters);
if (!cpuhw->disabled) {
@@ -737,6 +741,8 @@ int hw_perf_group_sched_in(struct perf_counter *group_leader,
long i, n, n0;
struct perf_counter *sub;

+ if (!ppmu)
+ return 0;
cpuhw = &__get_cpu_var(cpu_hw_counters);
n0 = cpuhw->n_counters;
n = collect_events(group_leader, ppmu->n_counter - n0,
@@ -1281,6 +1287,8 @@ void hw_perf_counter_setup(int cpu)
{
struct cpu_hw_counters *cpuhw = &per_cpu(cpu_hw_counters, cpu);

+ if (!ppmu)
+ return;
memset(cpuhw, 0, sizeof(*cpuhw));
cpuhw->mmcr[0] = MMCR0_FC;
}

\
 
 \ /
  Last update: 2009-08-07 10:33    [W:0.185 / U:0.184 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site