> On 06-May-2022, at 11:40 AM, Kajol Jain <kj...@linux.ibm.com> wrote:
>
> 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 <kj...@linux.ibm.com>
Reviewed-by: Athira Rajeev <atraj...@linux.vnet.ibm.com>
Thanks
Athira
> ---
> arch/powerpc/perf/isa207-common.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> 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,
> --
> 2.31.1
>
