svn commit: r338677 - in head: lib/libpmc sys/dev/hwpmc

[Matt Macy]

Author: mmacy
Date: Fri Sep 14 01:30:05 2018
New Revision: 338677
URL: https://svnweb.freebsd.org/changeset/base/338677

Log:
  hwpmc: set default rate if event description lacks one / filter rate against misuse
  
  Not all event descriptions have a sample rate (such as inst_retired.any)
  this will restore the legacy behavior of using 65536 in that case. It also
  prevents accidental API misuse that could lead to panic.
  
  PR:	230985
  Reported by:	markj
  Reviewed by:	markj
  Approved by:	re (gjb)
  Sponsored by:	Limelight Networks
  Differential Revision:	https://reviews.freebsd.org/D16958

Modified:
  head/lib/libpmc/libpmc_pmu_util.c
  head/sys/dev/hwpmc/hwpmc_mod.c

Modified: head/lib/libpmc/libpmc_pmu_util.c
==============================================================================
--- head/lib/libpmc/libpmc_pmu_util.c	Fri Sep 14 01:11:10 2018	(r338676)
+++ head/lib/libpmc/libpmc_pmu_util.c	Fri Sep 14 01:30:05 2018	(r338677)
@@ -237,6 +237,7 @@ pmu_parse_event(struct pmu_event_desc *ped, const char
 		return (ENOMEM);
 	r = event;
 	bzero(ped, sizeof(*ped));
+	ped->ped_period = DEFAULT_SAMPLE_COUNT;
 	ped->ped_umask = -1;
 	while ((kvp = strsep(&event, ",")) != NULL) {
 		key = strsep(&kvp, "=");

Modified: head/sys/dev/hwpmc/hwpmc_mod.c
==============================================================================
--- head/sys/dev/hwpmc/hwpmc_mod.c	Fri Sep 14 01:11:10 2018	(r338676)
+++ head/sys/dev/hwpmc/hwpmc_mod.c	Fri Sep 14 01:30:05 2018	(r338677)
@@ -61,6 +61,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sx.h>
 #include <sys/sysctl.h>
 #include <sys/sysent.h>
+#include <sys/syslog.h>
 #include <sys/systm.h>
 #include <sys/vnode.h>
 
@@ -3942,9 +3943,16 @@ pmc_syscall_handler(struct thread *td, void *syscall_a
 		pmc->pm_flags = pa.pm_flags;
 
 		/* XXX set lower bound on sampling for process counters */
-		if (PMC_IS_SAMPLING_MODE(mode))
-			pmc->pm_sc.pm_reloadcount = pa.pm_count;
-		else
+		if (PMC_IS_SAMPLING_MODE(mode)) {
+			/*
+			 * Don't permit requested sample rate to be less than 1000
+			 */
+			if (pa.pm_count < 1000)
+				log(LOG_WARNING,
+					"pmcallocate: passed sample rate %ju - setting to 1000\n",
+					(uintmax_t)pa.pm_count);
+			pmc->pm_sc.pm_reloadcount = MAX(1000, pa.pm_count);
+		} else
 			pmc->pm_sc.pm_initial = pa.pm_count;
 
 		/* switch thread to CPU 'cpu' */
@@ -4460,9 +4468,16 @@ pmc_syscall_handler(struct thread *td, void *syscall_a
 			break;
 		}
 
-		if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
-			pm->pm_sc.pm_reloadcount = sc.pm_count;
-		else
+		if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm))) {
+			/*
+			 * Don't permit requested sample rate to be less than 1000
+			 */
+			if (sc.pm_count < 1000)
+				log(LOG_WARNING,
+					"pmcsetcount: passed sample rate %ju - setting to 1000\n",
+					(uintmax_t)sc.pm_count);
+			pm->pm_sc.pm_reloadcount = MAX(1000, sc.pm_count);
+		} else
 			pm->pm_sc.pm_initial = sc.pm_count;
 	}
 	break;