From f36a1a133a947973efb8e6a1fbdcc23e4a011437 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 7 Aug 2009 16:59:45 +1000 Subject: [PATCH] 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 Cc: Peter Zijlstra Cc: benh@kernel.crashing.org Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/perf_counter.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c index 809fdf94b95f..70e1f57f7dd8 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; } -- 2.30.2