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libpmc: Use known pmc_cpuid buffer size

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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
MFC after:	1 week
Sponsored by:	iXsystems, Inc.
Differential Revision:	https://reviews.freebsd.org/D25679
This commit is contained in:
Ryan Moeller 2020-07-28 02:56:26 +00:00
parent fd35bfaecf
commit 24e337bec5
2 changed files with 8 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
lib/libpmc/libpmc_pmu_util.c
View File

@ -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);

2
sys/dev/hwpmc/hwpmc_mod.c
View File

@ -305,7 +305,7 @@ 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