Move array from header to C file to avoid that it gets defined in
every C file where the header is included:
In file included from arch/s390/kernel/perf_cpum_cf_common.c:19:
./arch/s390/include/asm/cpu_mcf.h:27:18: warning: ‘cpumf_ctr_ctl’ defined but not used [-Wunused-const-variable=]
27 | static const u64 cpumf_ctr_ctl[CPUMF_CTR_SET_MAX] = {
| ^~~~~~~~~~~~~
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Commit cf6acb8bdb ("s390/cpumf: Add support for complete counter set extraction")
allows access to the CPU Measurement Counter Facility via character
device /dev/hwctr. The access was exclusive via this device or
via perf_event_open() system call. Only one path at a time was
permitted. The CPU Measurement Counter Facility device driver blocked
access to other processes.
This patch removes this restriction and allows concurrent access to
the CPU Measurement Counter Facility from multiple processes at the same
time via perf_event_open() SVC and via /dev/hwctr device. The access
via /dev/hwctr device is still exclusive, only one process is allowed to
access this device.
This patch
- moves the /dev/hwctr device access from file perf_cpum_cf_diag.c.
to file perf_cpum_cf.c.
- use only one trace buffer .../s390dbf/cpum_cf.
- remove cfset_csd structure and includes its members it into the
structure cpu_cf_events. This results in one data structure and
simplifies the access.
- rework function familiy ctr_set_enable, ctr_set_disable, ctr_set_start
and ctr_set_stop which operate on a counter set number.
Now they operate on a counter set bit mask.
- move CF_DIAG event functionality to file perf_cpum_cf.c. It now
contains the complete functionality of the CPU Measurement Counter
Facility:
- Performance measurement support for counters using perf stat.
- Support for complete counter set extraction with device /dev/hwctr.
- Support for counter set extraction event CF_DIAG attached to
samples using perf record.
- removes file perf_cpum_cf_diag.c
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
The command 'perf stat -e cycles ...' triggers the following function
sequence in the CPU Measurement Facility counter device driver:
perf_pmu_event_init()
__hw_perf_event_init()
validate_ctr_auth()
validate_ctr_version()
During event creation, the counter number is checked in functions
validate_ctr_auth() and validate_ctr_version() to verify it is a valid
counter and supported by the hardware. If this is not the case, both
functions return an error and the event is not created. System call
perf_event_open() returns an error in this case.
Later on the event is installed in the kernel event subsystem and the
driver functions cpumf_pmu_add() and cpumf_pmu_commit_txn() are called
to install the counter event by the hardware.
Since both events have been verified at event creation, there is no need
to re-evaluate the authorization state. This can not change since on
* LPARs the authorization change requires a restart of the LPAR (and
thus a reboot of the kernel)
* DPMs can not take resources away, just add them.
Also the sequence of CPU Measurement facility counter device driver
calls is
cpumf_pmu_start_txn
cpumf_pmu_add
cpumf_pmu_start
cpumf_pmu_commit_txn
for every single event. Which means the condition in cpumf_pmu_add()
is never met and validate_ctr_auth() is never called.
This leaves the counter device driver transaction functions with
just one task:
start_txn: Verify a transaction is not in flight and call
perf_pmu_disable()
cancel_txn, commit_txn: Verify a transaction is in flight and call
perf_pmu_enable()
The same functionality is provided by the default transaction handling
functions in kernel/events/core.c. Use those by removing the
counter device driver private call back functions.
Suggested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
The function to calculate the size of counter sets is renamed from
cf_diag_ctrset_size() to cpum_cf_ctrset_size() and moved to the file
containing common functions for the CPU Measurement Counter Facility.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by : Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.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>
Introduce the ctr_stcctm() function as wrapper function to extract counters
from a particular counter set. Note that the counter set is part of the
stcctm instruction opcode, few indirections are necessary to specify the
counter set as variable.
Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
A preparation to move out common CPU-MF counter facility support
functions, first introduce a function that indicates whether the
support is ready to use.
Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Introduce a minimal interface for doing counter measurements of small
units of work within the kernel. Use the kernel_cpumcf_begin() function
start a measurement session and, later, stop it with kernel_cpumcf_end().
During the measreument session, you can enable and start/stop counter sets
by using ctr_set_* functions. To make these changes effective use the
lcctl() function. You can then use the ecctr() function to extract counters
from the different counter sets.
Please note that you have to check whether the counter sets to be enabled
are authorized.
Note that when a measurement session is active, other users cannot perform
counter measurements. In such cases, kernel_cpumcf_begin() indicates this
with returning -EBUSY. If the counter facility is not available,
kernel_cpumcf_begin() returns -ENODEV.
Note that this interface is restricted to the current CPU and, thus,
preemption must be turned off.
Example:
u32 state, err;
u64 cycles, insn;
err = kernel_cpumcf_begin();
if (err)
goto out_busy;
state = 0;
ctr_set_enable(&state, CPUMF_CTR_SET_BASIC);
ctr_set_start(&state, CPUMF_CTR_SET_BASIC);
err = lcctl(state);
if (err)
goto ;
/* ... do your work ... */
ctr_set_stop(&state, CPUMF_CTR_SET_BASIC);
err = lcctl(state);
if (err)
goto out;
cycles = insn = 0;
ecctr(0, &cycles);
ecctr(1, &insn);
/* ... */
kernel_cpumcf_end();
out_busy:
Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
During a __kernel_cpumcf_begin()/end() session, save measurement alerts
for the counter facility in the per-CPU cpu_cf_events variable.
Users can obtain and, optionally, clear the alerts by calling
kernel_cpumcf_alert() to specifically handle alerts.
Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Make the struct cpu_cf_events and the respective per-CPU variable available
to in-kernel users. Access to this per-CPU variable shall be done between
the calls to __kernel_cpumcf_begin() and __kernel_cpumcf_end().
Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Prepare the counter facility support to be used by other in-kernel
users. The first step introduces the __kernel_cpumcf_begin() and
__kernel_cpumcf_end() functions to reserve the counter facility
for doing measurements and to release after the measurements are
done.
Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Move counter set specific controls and functions to the asm/cpu_mcf.h
header file containg all counter facility support definitions. Also
adapt few variable names and header file includes. No functional changes.
Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
