Patch "powerpc/perf: Fix oops when grouping different pmu events" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/perf: Fix oops when grouping different pmu events

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-perf-fix-oops-when-grouping-different-pmu-events.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ravi Bangoria <[email protected]>
Date: Thu, 30 Nov 2017 14:03:22 +0530
Subject: powerpc/perf: Fix oops when grouping different pmu events

From: Ravi Bangoria <[email protected]>

[ 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().

---
 arch/powerpc/perf/core-book3s.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -1381,7 +1381,7 @@ 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;

@@ -1389,7 +1389,7 @@ 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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/perf-top-fix-window-dimensions-change-handling.patch queue-4.9/powerpc-perf-fix-oops-when-grouping-different-pmu-events.patch