Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit fcc77f50 authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Martin Schwidefsky
Browse files

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



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: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 69f239ed

arch/s390/include/asm/cpu_mf.h

+9 −4
Original line number Diff line number Diff line
@@ -115,10 +115,15 @@ struct hws_data_entry { 
} __packed;



struct hws_trailer_entry {

	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;	 /*				      */

arch/s390/kernel/perf_cpum_sf.c

+8 −4
Original line number Diff line number Diff line
@@ -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++;