svn commit: r363831 - in stable/12: lib/libpmc sys/dev/hwpmc

[Ryan Moeller]

Author: freqlabs
Date: Tue Aug  4 12:04:47 2020
New Revision: 363831
URL: https://svnweb.freebsd.org/changeset/base/363831

Log:
  MFC r363630:
  
  libpmc: Use known pmc_cpuid buffer size
  
  Use the existing PMC_CPUID_LEN to size pmc_cpuid in the kernel and various
  buffers for reading it in libpmc.  This avoids some extra syscalls and
  malloc/frees.
  
  While in here, use strlcpy to copy a user-provided cpuid string instead of
  memcpy, to make sure we terminate the buffer.
  
  Reviewed by:    mav
  Sponsored by:   iXsystems, Inc.
  Differential Revision:  https://reviews.freebsd.org/D25679

Modified:
  stable/12/lib/libpmc/libpmc_pmu_util.c
  stable/12/sys/dev/hwpmc/hwpmc_mod.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/lib/libpmc/libpmc_pmu_util.c
==============================================================================
--- stable/12/lib/libpmc/libpmc_pmu_util.c	Tue Aug  4 11:13:13 2020	(r363830)
+++ stable/12/lib/libpmc/libpmc_pmu_util.c	Tue Aug  4 12:04:47 2020	(r363831)
@@ -30,6 +30,7 @@
 
 #include <sys/types.h>
 #include <sys/errno.h>
+#include <sys/pmc.h>
 #include <sys/sysctl.h>
 #include <stddef.h>
 #include <stdlib.h>
@@ -89,20 +90,13 @@ static struct pmu_alias pmu_amd_alias_table[] = {
 static pmu_mfr_t
 pmu_events_mfr(void)
 {
-	char *buf;
-	size_t s;
+	char buf[PMC_CPUID_LEN];
+	size_t s = sizeof(buf);
 	pmu_mfr_t mfr;
 
-	if (sysctlbyname("kern.hwpmc.cpuid", (void *)NULL, &s,
+	if (sysctlbyname("kern.hwpmc.cpuid", buf, &s,
 	    (void *)NULL, 0) == -1)
 		return (PMU_INVALID);
-	if ((buf = malloc(s + 1)) == NULL)
-		return (PMU_INVALID);
-	if (sysctlbyname("kern.hwpmc.cpuid", buf, &s,
-		(void *)NULL, 0) == -1) {
-		free(buf);
-		return (PMU_INVALID);
-	}
 	if (strcasestr(buf, "AuthenticAMD") != NULL ||
 	    strcasestr(buf, "HygonGenuine") != NULL)
 		mfr = PMU_AMD;
@@ -110,7 +104,6 @@ pmu_events_mfr(void)
 		mfr = PMU_INTEL;
 	else
 		mfr = PMU_INVALID;
-	free(buf);
 	return (mfr);
 }
 
@@ -169,17 +162,14 @@ pmu_events_map_get(const char *cpuid)
 {
 	regex_t re;
 	regmatch_t pmatch[1];
-	size_t s;
-	char buf[64];
+	char buf[PMC_CPUID_LEN];
+	size_t s = sizeof(buf);
 	int match;
 	const struct pmu_events_map *pme;
 
 	if (cpuid != NULL) {
-		memcpy(buf, cpuid, 64);
+		strlcpy(buf, cpuid, s);
 	} else {
-		if (sysctlbyname("kern.hwpmc.cpuid", (void *)NULL, &s,
-		    (void *)NULL, 0) == -1)
-			return (NULL);
 		if (sysctlbyname("kern.hwpmc.cpuid", buf, &s,
 		    (void *)NULL, 0) == -1)
 			return (NULL);

Modified: stable/12/sys/dev/hwpmc/hwpmc_mod.c
==============================================================================
--- stable/12/sys/dev/hwpmc/hwpmc_mod.c	Tue Aug  4 11:13:13 2020	(r363830)
+++ stable/12/sys/dev/hwpmc/hwpmc_mod.c	Tue Aug  4 12:04:47 2020	(r363831)
@@ -304,7 +304,7 @@ static int pmc_callchaindepth = PMC_CALLCHAIN_DEPTH;
 SYSCTL_INT(_kern_hwpmc, OID_AUTO, callchaindepth, CTLFLAG_RDTUN,
     &pmc_callchaindepth, 0, "depth of call chain records");
 
-char pmc_cpuid[64];
+char pmc_cpuid[PMC_CPUID_LEN];
 SYSCTL_STRING(_kern_hwpmc, OID_AUTO, cpuid, CTLFLAG_RD,
 	pmc_cpuid, 0, "cpu version string");
 #ifdef	HWPMC_DEBUG