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s390/cpum_sf: Atomically reset trailer entry fields of sample-data-blocks

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Ensure to reset the sample-data-block full indicator and the overflow counter
at the same time.  This must be done atomically because the sampling hardware
is still active while full sample-data-block is processed.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Hendrik Brueckner 2013-12-12 17:26:51 +01:00 committed by Martin Schwidefsky
parent 69f239ed33
commit fcc77f5073
2 changed files with 17 additions and 8 deletions
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13
arch/s390/include/asm/cpu_mf.h
View File

@ -115,10 +115,15 @@ struct hws_data_entry {
} __packed;
struct hws_trailer_entry {
unsigned int f:1; /* 0 - Block Full Indicator */
unsigned int a:1; /* 1 - Alert request control */
unsigned int t:1; /* 2 - Timestamp format */
unsigned long long:61; /* 3 - 63: Reserved */
union {
struct {
unsigned int f:1; /* 0 - Block Full Indicator */
unsigned int a:1; /* 1 - Alert request control */
unsigned int t:1; /* 2 - Timestamp format */
unsigned long long:61; /* 3 - 63: Reserved */
};
unsigned long long flags; /* 0 - 63: All indicators */
};
unsigned long long overflow; /* 64 - sample Overflow count */
unsigned long long timestamp; /* 16 - time-stamp */
unsigned long long timestamp1; /* */

12
arch/s390/kernel/perf_cpum_sf.c
View File

@ -953,7 +953,7 @@ static void hw_perf_event_update(struct perf_event *event, int flush_all)
struct hw_perf_event *hwc = &event->hw;
struct hws_trailer_entry *te;
unsigned long *sdbt;
unsigned long long event_overflow, sampl_overflow, num_sdb;
unsigned long long event_overflow, sampl_overflow, num_sdb, te_flags;
int done;
sdbt = (unsigned long *) TEAR_REG(hwc);
@ -990,9 +990,13 @@ static void hw_perf_event_update(struct perf_event *event, int flush_all)
hw_collect_samples(event, sdbt, &event_overflow);
num_sdb++;
/* Reset trailer */
xchg(&te->overflow, 0);
xchg((unsigned char *) te, 0x40);
/* Reset trailer (using compare-double-and-swap) */
do {
te_flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK;
te_flags |= SDB_TE_ALERT_REQ_MASK;
} while (!cmpxchg_double(&te->flags, &te->overflow,
te->flags, te->overflow,
te_flags, 0ULL));
/* Advance to next sample-data-block */
sdbt++;