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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@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: benh@kernel.crashing.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul Mackerras 2009-08-07 16:59:45 +10:00 committed by Ingo Molnar
parent b26bc5a7f8
commit f36a1a133a
1 changed files with 8 additions and 0 deletions
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8
arch/powerpc/kernel/perf_counter.c
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@ -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;
}