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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 061/145] powerpc/perf: Fix oops when grouping different pmu events
Date:   Fri, 23 Feb 2018 19:26:07 +0100
Message-Id: <20180223170732.680009918@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

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
@@ -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;