Commit-ID: 8ca7b4f1a6e3bba0724950c52b973d22135c0bd9
Gitweb: http://git.kernel.org/tip/8ca7b4f1a6e3bba0724950c52b973d22135c0bd9
Author: Paul Mackerras <paulus@xxxxxxxxx>
AuthorDate: Fri, 7 Aug 2009 16:59:45 +1000
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sat, 8 Aug 2009 13:35:21 +0200
perf_counter/powerpc: Fix 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@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: benh@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
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;
}
--
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