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Commit cf6acb8bdb1d ("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>
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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>
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The following BUG message was triggered repeatedly when complete counter
sets are extracted from the CPUMF:
BUG: using smp_processor_id() in preemptible [00000000]
code: psvc-readsets/7759
caller is cf_diag_needspace+0x2c/0x100
CPU: 7 PID: 7759 Comm: psvc-readsets Not tainted 5.12.0
Hardware name: IBM 3906 M03 703 (LPAR)
Call Trace:
[<00000000c7043f78>] show_stack+0x90/0xf8
[<00000000c705776a>] dump_stack+0xba/0x108
[<00000000c705d91c>] check_preemption_disabled+0xec/0xf0
[<00000000c63eb1c4>] cf_diag_needspace+0x2c/0x100
[<00000000c63ecbcc>] cf_diag_ioctl_start+0x10c/0x240
[<00000000c63ece9a>] cf_diag_ioctl+0x19a/0x238
[<00000000c675f3f4>] __s390x_sys_ioctl+0xc4/0x100
[<00000000c63ca762>] do_syscall+0x82/0xd0
[<00000000c705bdd8>] __do_syscall+0xc0/0xd8
[<00000000c706d532>] system_call+0x72/0x98
2 locks held by psvc-readsets/7759:
#0: 00000000c75a57c0 (cpu_hotplug_lock){++++}-{0:0},
at: cf_diag_ioctl+0x44/0x238
#1: 00000000c75a3078 (cf_diag_ctrset_mutex){+.+.}-{3:3},
at: cf_diag_ioctl+0x54/0x238
This issue is a missing get_cpu_ptr/put_cpu_ptr pair in function
cf_diag_needspace. Add it.
Fixes: cf6acb8bdb1d ("s390/cpumf: Add support for complete counter set extraction")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Suggested-by: Hendrick Brueckner <brueckner@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Remove the 60 seconds read interval limit. Do not impose any limit
at all and allow read of complete counter sets.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Add support to the CPU Measurement counter facility device driver
to extract complete counter sets per CPU and per counter set from user
space. This includes a new device named /dev/hwctr and support
for the device driver functions open, close and ioctl. Other
functions are not supported.
The ioctl command supports 3 subcommands:
S390_HWCTR_START: enables counter sets on a list of CPUs.
S390_HWCTR_STOP: disables counter sets on a list of CPUs.
S390_HWCTR_READ: reads counter sets on a list of CPUs.
The ioctl(..., S390_HWCTR_READ, ...) is the only subcommand which
returns data. It requires member data_bytes to be positive and
indicates the maximum amount of data available to store counter set
data. The other ioctl() subcommands do not use this member and it
should be set to zero.
The S390_HWCTR_READ subcommand returns the following data:
The cpuset data is flattened using the following scheme, stored in member
data:
0x0 0x8 0xc 0x10 0x10 0x18 0x20 0x28 0xU-1
+---------+-----+---------+-----+---------+-----+-----+------+------+
| no_cpus | cpu | no_sets | set | no_cnts | cv1 | cv2 | .... | cv_n |
+---------+-----+---------+-----+---------+-----+-----+------+------+
0xU 0xU+4 0xU+8 0xU+10 0xV-1
+-----+---------+-----+-----+------+------+
| set | no_cnts | cv1 | cv2 | .... | cv_n |
+-----+---------+-----+-----+------+------+
0xV 0xV+4 0xV+8 0xV+c
+-----+---------+-----+---------+-----+-----+------+------+
| cpu | no_sets | set | no_cnts | cv1 | cv2 | .... | cv_n |
+-----+---------+-----+---------+-----+-----+------+------+
U and V denote arbitrary hexadezimal addresses.
The first integer represents the number of CPUs data was extracted
from. This is followed by CPU number and number of counter sets extracted.
Both are two integer values. This is followed by the set identifer
and number of counters extracted. Both are two integer values. This is
followed by the counter values, each element is eight bytes in size.
The S390_HWCTR_READ ioctl subcommand is also limited to one call per
minute. This ensures that an application does not read out the
counter sets too often and reduces the overall CPU performance.
The complete counter set extraction is an expensive operation.
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Convert tod_clock_base to union tod_clock. This simplifies quite a bit
of code and also fixes a bug in read_persistent_clock64();
void read_persistent_clock64(struct timespec64 *ts)
{
__u64 delta;
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
get_tod_clock_ext(clk);
*(__u64 *) &clk[1] -= delta;
if (*(__u64 *) &clk[1] > delta)
clk[0]--;
ext_to_timespec64(clk, ts);
}
Assume &clk[1] == 3 and delta == 2; then after the substraction the if
condition becomes true and the epoch part of the clock is decremented
by one because of an assumed overflow, even though there is none.
Fix this by using 128 bit arithmetics and let the compiler do the
right thing:
void read_persistent_clock64(struct timespec64 *ts)
{
union tod_clock clk;
u64 delta;
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
store_tod_clock_ext(&clk);
clk.eitod -= delta;
ext_to_timespec64(&clk, ts);
}
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use get_tod_clock_fast() instead of store_tod_clock(), since
store_tod_clock() can be very slow.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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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>
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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>
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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>
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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>
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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: fe5908bccc56 ("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>
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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>
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