This is a note to let you know that I've just added the patch titled
powerpc/perf: Fix the threshold compare group constraint for power9
to the 5.18-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-the-threshold-compare-group-constra.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3c82dc582f8f4b917eb6432cb1e6b8c730025abe
Author: Kajol Jain <kjain@xxxxxxxxxxxxx>
Date: Fri May 6 11:40:15 2022 +0530
powerpc/perf: Fix the threshold compare group constraint for power9
[ Upstream commit ab0cc6bbf0c812731c703ec757fcc3fc3a457a34 ]
Thresh compare bits for a event is used to program thresh compare
field in Monitor Mode Control Register A (MMCRA: 9-18 bits for power9).
When scheduling events as a group, all events in that group should
match value in threshold bits (like thresh compare, thresh control,
thresh select). Otherwise event open for the sibling events should fail.
But in the current code, incase thresh compare bits are not valid,
we are not failing in group_constraint function which can result
in invalid group schduling.
Fix the issue by returning -1 incase event is threshold and threshold
compare value is not valid.
Thresh control bits in the event code is used to program thresh_ctl
field in Monitor Mode Control Register A (MMCRA: 48-55). In below example,
the scheduling of group events PM_MRK_INST_CMPL (873534401e0) and
PM_THRESH_MET (8734340101ec) is expected to fail as both event
request different thresh control bits and invalid thresh compare value.
Result before the patch changes:
[command]# perf stat -e "{r8735340401e0,r8734340101ec}" sleep 1
Performance counter stats for 'sleep 1':
11,048 r8735340401e0
1,967 r8734340101ec
1.001354036 seconds time elapsed
0.001421000 seconds user
0.000000000 seconds sys
Result after the patch changes:
[command]# perf stat -e "{r8735340401e0,r8734340101ec}" sleep 1
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument)
for event (r8735340401e0).
/bin/dmesg | grep -i perf may provide additional information.
Fixes: 78a16d9fc1206 ("powerpc/perf: Avoid FAB_*_MATCH checks for power9")
Signed-off-by: Kajol Jain <kjain@xxxxxxxxxxxxx>
Reviewed-by: Athira Rajeev <atrajeev@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220506061015.43916-2-kjain@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/powerpc/perf/isa207-common.c b/arch/powerpc/perf/isa207-common.c
index 013b06af6fe6..bb5d64862bc9 100644
--- a/arch/powerpc/perf/isa207-common.c
+++ b/arch/powerpc/perf/isa207-common.c
@@ -508,7 +508,8 @@ int isa207_get_constraint(u64 event, unsigned long *maskp, unsigned long *valp,
if (event_is_threshold(event) && is_thresh_cmp_valid(event)) {
mask |= CNST_THRESH_MASK;
value |= CNST_THRESH_VAL(event >> EVENT_THRESH_SHIFT);
- }
+ } else if (event_is_threshold(event))
+ return -1;
} else {
/*
* Special case for PM_MRK_FAB_RSP_MATCH and PM_MRK_FAB_RSP_MATCH_CYC,
