Linux-next commit titled "perf/core: Optimize perf_init_event()"
changed the semantics of PMU device driver registration.
It was done to speed up the lookup/handling of PMU device driver
specific events. It also enforces that only one PMU device
driver will be registered of type PERF_EVENT_RAW.
This change added these line in function perf_pmu_register():
...
+ ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL);
+ if (ret < 0)
goto free_pdc;
+
+ WARN_ON(type >= 0 && ret != type);
The warn_on generates a message. We have 3 PMU device drivers,
each registered as type PERF_TYPE_RAW.
The cf_diag device driver (arch/s390/kernel/perf_cpumf_cf_diag.c)
always hits the WARN_ON because it is the second PMU device driver
(after sampling device driver arch/s390/kernel/perf_cpumf_sf.c)
which is registered as type 4 (PERF_TYPE_RAW).
So when the sampling device driver is registered, ret has value 4.
When cf_diag device driver is registered with type 4,
ret has value of 5 and WARN_ON fires.
Adjust the PMU device drivers for s390 to support the new
semantics required by perf_pmu_register().
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Use consistant debug print format of the form variable
blank value.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Since there is really no reason for cf_diag_csd per cpu variable to be
globally visible make it static to avoid the following sparse warning:
arch/s390/kernel/perf_cpum_cf_diag.c:37:1: warning: symbol 'cf_diag_csd' was not declared. Should it be static?
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Add support for the CPU-Measurement Facility counter
second version number 6. This number is used to detect some
more counters in the crypto counter set and the extended
counter set.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Function __hw_perf_event_init() used a CPU variable without
ensuring CPU preemption has been disabled. This caused the
following warning in the kernel log:
[ 7.277085] BUG: using smp_processor_id() in preemptible
[00000000] code: cf-csdiag/1892
[ 7.277111] caller is cf_diag_event_init+0x13a/0x338
[ 7.277122] CPU: 10 PID: 1892 Comm: cf-csdiag Not tainted
5.0.0-20190318.rc0.git0.9e1a11e0f602.300.fc29.s390x+debug #1
[ 7.277131] Hardware name: IBM 2964 NC9 712 (LPAR)
[ 7.277139] Call Trace:
[ 7.277150] ([<000000000011385a>] show_stack+0x82/0xd0)
[ 7.277161] [<0000000000b7a71a>] dump_stack+0x92/0xd0
[ 7.277174] [<00000000007b7e9c>] check_preemption_disabled+0xe4/0x100
[ 7.277183] [<00000000001228aa>] cf_diag_event_init+0x13a/0x338
[ 7.277195] [<00000000002cf3aa>] perf_try_init_event+0x72/0xf0
[ 7.277204] [<00000000002d0bba>] perf_event_alloc+0x6fa/0xce0
[ 7.277214] [<00000000002dc4a8>] __s390x_sys_perf_event_open+0x398/0xd50
[ 7.277224] [<0000000000b9e8f0>] system_call+0xdc/0x2d8
[ 7.277233] 2 locks held by cf-csdiag/1892:
[ 7.277241] #0: 00000000976f5510 (&sig->cred_guard_mutex){+.+.},
at: __s390x_sys_perf_event_open+0xd2e/0xd50
[ 7.277257] #1: 00000000363b11bd (&pmus_srcu){....},
at: perf_event_alloc+0x52e/0xce0
The variable is now accessed in proper context. Use
get_cpu_var()/put_cpu_var() pair to disable
preemption during access.
As the hardware authorization settings apply to all CPUs, it
does not matter which CPU is used to check the authorization setting.
Remove the event->count assignment. It is not needed as function
perf_event_alloc() allocates memory for the event with kzalloc() and
thus count is already set to zero.
Fixes: fe5908bccc ("s390/cpum_cf_diag: Add support for s390 counter facility diagnostic trace")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Introduce a PMU device named cpum_cf_diag. It extracts the
values of all counters in all authorized counter sets and stores
them as event raw data. This is done with the STORE CPU COUNTER
MULTIPLE instruction to speed up access. All counter sets
fit into one buffer. The values of each counter are taken
when the event is started on the performance sub-system and when
the event is stopped.
This results in counter values available at the start and
at the end of the measurement time frame. The difference is
calculated for each counter. The differences of all
counters are then saved as event raw data in the perf.data
file.
The counter values are accompanied by the time stamps
when the counter set was started and when the counter set
was stopped. This data is part of a trailer entry which
describes the time frame, counter set version numbers,
CPU speed, and machine type for later analysis.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
