[PATCH 5.4 34/60] s390/cpumf: Handle events cycles and instructions identical

Greg Kroah-Hartman
2022-06-27T11:34:05Z

From: Thomas Richter <tmricht@linux.ibm.com>

[ Upstream commit be857b7f77d130dbbd47c91fc35198b040f35865 ]

Events CPU_CYCLES and INSTRUCTIONS can be submitted with two different
perf_event attribute::type values:
- PERF_TYPE_HARDWARE: when invoked via perf tool predefined events name
cycles or cpu-cycles or instructions.
- pmu->type: when invoked via perf tool event name cpu_cf/CPU_CYLCES/ or
cpu_cf/INSTRUCTIONS/. This invocation also selects the PMU to which
the event belongs.
Handle both type of invocations identical for events CPU_CYLCES and
INSTRUCTIONS. They address the same hardware.
The result is different when event modifier exclude_kernel is also set.
Invocation with event modifier for user space event counting fails.

Output before:

# perf stat -e cpum_cf/cpu_cycles/u -- true

Performance counter stats for 'true':

<not supported> cpum_cf/cpu_cycles/u

0.000761033 seconds time elapsed

0.000076000 seconds user
0.000725000 seconds sys

#

Output after:
# perf stat -e cpum_cf/cpu_cycles/u -- true

Performance counter stats for 'true':

349,613 cpum_cf/cpu_cycles/u

0.000844143 seconds time elapsed

0.000079000 seconds user
0.000800000 seconds sys
#

Fixes: 6a82e23f45fe ("s390/cpumf: Adjust registration of s390 PMU device drivers")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
[agordeev@linux.ibm.com corrected commit ID of Fixes commit]
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/kernel/perf_cpum_cf.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index 0eb1d1cc53a8..dddb32e53db8 100644
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -292,6 +292,26 @@ static int __hw_perf_event_init(struct perf_event *event, unsigned int type)
return err;
}

+/* Events CPU_CYLCES and INSTRUCTIONS can be submitted with two different
+ * attribute::type values:
+ * - PERF_TYPE_HARDWARE:
+ * - pmu->type:
+ * Handle both type of invocations identical. They address the same hardware.
+ * The result is different when event modifiers exclude_kernel and/or
+ * exclude_user are also set.
+ */
+static int cpumf_pmu_event_type(struct perf_event *event)
+{
+ u64 ev = event->attr.config;
+
+ if (cpumf_generic_events_basic[PERF_COUNT_HW_CPU_CYCLES] == ev ||
+ cpumf_generic_events_basic[PERF_COUNT_HW_INSTRUCTIONS] == ev ||
+ cpumf_generic_events_user[PERF_COUNT_HW_CPU_CYCLES] == ev ||
+ cpumf_generic_events_user[PERF_COUNT_HW_INSTRUCTIONS] == ev)
+ return PERF_TYPE_HARDWARE;
+ return PERF_TYPE_RAW;
+}
+
static int cpumf_pmu_event_init(struct perf_event *event)
{
unsigned int type = event->attr.type;
@@ -301,7 +321,7 @@ static int cpumf_pmu_event_init(struct perf_event *event)
err = __hw_perf_event_init(event, type);
else if (event->pmu->type == type)
/* Registered as unknown PMU */
- err = __hw_perf_event_init(event, PERF_TYPE_RAW);
+ err = __hw_perf_event_init(event, cpumf_pmu_event_type(event));
else
return -ENOENT;

--
2.35.1