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sparc64: Fix pcr_ops initialization and usage bugs. 

Christopher reports that perf_event_print_debug() can crash in uniprocessor
builds.  The crash is due to pcr_ops being NULL.

This happens because pcr_arch_init() is only invoked by smp_cpus_done() which
only executes in SMP builds.

init_hw_perf_events() is closely intertwined with pcr_ops being setup properly,
therefore:

1) Call pcr_arch_init() early on from init_hw_perf_events(), instead of
   from smp_cpus_done().

2) Do not hook up a PMU type if pcr_ops is NULL after pcr_arch_init().

3) Move init_hw_perf_events to a later initcall so that it we will be
   sure to invoke pcr_arch_init() after all cpus are brought up.

Finally, guard the one naked sequence of pcr_ops dereferences in
__global_pmu_self() with an appropriate NULL check.

Reported-by: Christopher Alexander Tobias Schulze <cat.schulze@alice-dsl.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
David S. Miller 2014-08-11 15:38:46 -07:00
parent 58556104e9
commit 8bccf5b313
3 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/sparc/kernel/perf_event.c
View File

@ -1671,9 +1671,12 @@ static bool __init supported_pmu(void)
static int __init init_hw_perf_events(void)
{
int err;
pr_info("Performance events: ");
if (!supported_pmu()) {
err = pcr_arch_init();
if (err || !supported_pmu()) {
pr_cont("No support for PMU type '%s'\n", sparc_pmu_type);
return 0;
}
@ -1685,7 +1688,7 @@ static int __init init_hw_perf_events(void)
return 0;
}
early_initcall(init_hw_perf_events);
pure_initcall(init_hw_perf_events);
void perf_callchain_kernel(struct perf_callchain_entry *entry,
struct pt_regs *regs)

3
arch/sparc/kernel/process_64.c
View File

@ -312,6 +312,9 @@ static void __global_pmu_self(int this_cpu)
struct global_pmu_snapshot *pp;
int i, num;
if (!pcr_ops)
return;
pp = &global_cpu_snapshot[this_cpu].pmu;
num = 1;

1
arch/sparc/kernel/smp_64.c
View File

@ -1383,7 +1383,6 @@ void __cpu_die(unsigned int cpu)
void __init smp_cpus_done(unsigned int max_cpus)
{
pcr_arch_init();
}
void smp_send_reschedule(int cpu)