3.18-stable review patch. If anyone has any objections, please let me know.
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From: Ravi Bangoria ravi.bangoria@linux.vnet.ibm.com
[ Upstream commit 5aa04b3eb6fca63d2e9827be656dcadc26d54e11 ]
When user tries to group imc (In-Memory Collections) event with normal event, (sometime) kernel crashes with following log:
Faulting instruction address: 0x00000000 [link register ] c00000000010ce88 power_check_constraints+0x128/0x980 ... c00000000010e238 power_pmu_event_init+0x268/0x6f0 c0000000002dc60c perf_try_init_event+0xdc/0x1a0 c0000000002dce88 perf_event_alloc+0x7b8/0xac0 c0000000002e92e0 SyS_perf_event_open+0x530/0xda0 c00000000000b004 system_call+0x38/0xe0
'event_base' field of 'struct hw_perf_event' is used as flags for normal hw events and used as memory address for imc events. While grouping these two types of events, collect_events() tries to interpret imc 'event_base' as a flag, which causes a corruption resulting in a crash.
Consider only those events which belongs to 'perf_hw_context' in collect_events().
Signed-off-by: Ravi Bangoria ravi.bangoria@linux.vnet.ibm.com Reviewed-By: Madhavan Srinivasan maddy@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/perf/core-book3s.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -1376,7 +1376,7 @@ static int collect_events(struct perf_ev int n = 0; struct perf_event *event;
- if (!is_software_event(group)) { + if (group->pmu->task_ctx_nr == perf_hw_context) { if (n >= max_count) return -1; ctrs[n] = group; @@ -1384,7 +1384,7 @@ static int collect_events(struct perf_ev events[n++] = group->hw.config; } list_for_each_entry(event, &group->sibling_list, group_entry) { - if (!is_software_event(event) && + if (event->pmu->task_ctx_nr == perf_hw_context && event->state != PERF_EVENT_STATE_OFF) { if (n >= max_count) return -1;