On 6/2/20 8:26 AM, Alexey Kardashevskiy wrote:
The bhrb_filter_map ("The Branch History Rolling Buffer") callback is
only defined in raw CPUs' power_pmu structs. The "architected" CPUs use
generic_compat_pmu which does not have this callback and crashed occur.
This add a NULL pointer check for bhrb_filter_map() which behaves as if
the callback returned an error.
This does not add the same check for config_bhrb() as the only caller
checks for cpuhw->bhrb_users which remains zero if bhrb_filter_map==0.
Changes looks fine.
Reviewed-by: Madhavan Srinivasan <ma...@linux.ibm.com>
The commit be80e758d0c2e ('powerpc/perf: Add generic compat mode pmu
driver')
which introduced generic_compat_pmu was merged in v5.2. So we need to
CC stable starting from 5.2 :( . My bad, sorry.
Maddy
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
arch/powerpc/perf/core-book3s.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 3dcfecf858f3..36870569bf9c 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1515,9 +1515,16 @@ static int power_pmu_add(struct perf_event *event, int
ef_flags)
ret = 0;
out:
if (has_branch_stack(event)) {
- power_pmu_bhrb_enable(event);
- cpuhw->bhrb_filter = ppmu->bhrb_filter_map(
- event->attr.branch_sample_type);
+ u64 bhrb_filter = -1;
+
+ if (ppmu->bhrb_filter_map)
+ bhrb_filter = ppmu->bhrb_filter_map(
+ event->attr.branch_sample_type);
+
+ if (bhrb_filter != -1) {
+ cpuhw->bhrb_filter = bhrb_filter;
+ power_pmu_bhrb_enable(event); /* Does bhrb_users++ */
+ }
}
perf_pmu_enable(event->pmu);
@@ -1839,7 +1846,6 @@ static int power_pmu_event_init(struct perf_event *event)
int n;
int err;
struct cpu_hw_events *cpuhw;
- u64 bhrb_filter;
if (!ppmu)
return -ENOENT;
@@ -1945,7 +1951,10 @@ static int power_pmu_event_init(struct perf_event *event)
err = power_check_constraints(cpuhw, events, cflags, n + 1);
if (has_branch_stack(event)) {
- bhrb_filter = ppmu->bhrb_filter_map(
+ u64 bhrb_filter = -1;
+
+ if (ppmu->bhrb_filter_map)
+ bhrb_filter = ppmu->bhrb_filter_map(
event->attr.branch_sample_type);
if (bhrb_filter == -1) {
