3.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
[ Upstream commit 8bccf5b313180faefce38e0d1140f76e0f327d28 ]
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@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/sparc/kernel/perf_event.c | 7 +++++--
arch/sparc/kernel/process_64.c | 3 +++
arch/sparc/kernel/smp_64.c | 1 -
3 files changed, 8 insertions(+), 3 deletions(-)
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -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(vo
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)
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -312,6 +312,9 @@ static void __global_pmu_self(int this_c
struct global_pmu_snapshot *pp;
int i, num;
+ if (!pcr_ops)
+ return;
+
pp = &global_cpu_snapshot[this_cpu].pmu;
num = 1;
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -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)
--
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