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| author |   Thomas Richter <tmricht@linux.ibm.com> | 2019-09-16 11:21:23 +0200 |
|---|---|---|
| committer |   Vasily Gorbik <gor@linux.ibm.com> | 2019-09-19 12:56:07 +0200 |
| commit | 2cb549a821e9daf441b62d55ca8eb6a9c22acf95 (patch) | |
| tree | 6b5e286bf68c8a39d82109c41fd8aa045235db1f /arch/s390/include/asm/perf_event.h | |
| parent | s390/zcrypt: CEX7S exploitation support (diff) | |
| download | linux-dev-2cb549a821e9daf441b62d55ca8eb6a9c22acf95.tar.xz linux-dev-2cb549a821e9daf441b62d55ca8eb6a9c22acf95.zip | |
s390/cpum_sf: Support ioctl PERF_EVENT_IOC_PERIOD
A perf_event can be set up to deliver overflow notifications
via SIGIO signal. The setup of the event is:
1. create event with perf_event_open()
2. assign it a signal for I/O notification with fcntl()
3. Install signal handler and consume samples
The initial setup of perf_event_open() determines the
period/frequency time span needed to elapse before each signal
is delivered to the user process.
While the event is active, system call
ioctl(.., PERF_EVENT_IOC_PERIOD, value) can be used the change
the frequency/period time span of the active event.
The remaining signal handler invocations honour the new value.
This does not work on s390. In fact the time span does not change
regardless of ioctl's third argument 'value'. The call succeeds
but the time span does not change.
Support this behavior and make it common with other platforms.
This is achieved by changing the interval value of the sampling
control block accordingly and feed this new value every time
the event is enabled using pmu_event_enable().
Before this change the interval value was set only once at
pmu_event_add() and never changed.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/perf_event.h')
| -rw-r--r-- | arch/s390/include/asm/perf_event.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/include/asm/perf_event.h b/arch/s390/include/asm/perf_event.h index 560d8f766ddf..4652ffffe0b2 100644 --- a/arch/s390/include/asm/perf_event.h +++ b/arch/s390/include/asm/perf_event.h @@ -60,6 +60,7 @@ struct perf_sf_sde_regs { #define PERF_CPUM_SF_MODE_MASK (PERF_CPUM_SF_BASIC_MODE| \ PERF_CPUM_SF_DIAG_MODE) #define PERF_CPUM_SF_FULL_BLOCKS 0x0004 /* Process full SDBs only */ +#define PERF_CPUM_SF_FREQ_MODE 0x0008 /* Sampling with frequency */ #define REG_NONE 0 #define REG_OVERFLOW 1 @@ -70,5 +71,6 @@ struct perf_sf_sde_regs { #define SAMPL_FLAGS(hwc) ((hwc)->config_base) #define SAMPL_DIAG_MODE(hwc) (SAMPL_FLAGS(hwc) & PERF_CPUM_SF_DIAG_MODE) #define SDB_FULL_BLOCKS(hwc) (SAMPL_FLAGS(hwc) & PERF_CPUM_SF_FULL_BLOCKS) +#define SAMPLE_FREQ_MODE(hwc) (SAMPL_FLAGS(hwc) & PERF_CPUM_SF_FREQ_MODE) #endif /* _ASM_S390_PERF_EVENT_H */ |