Now the get_cpuid__str function returns the MIDR string of the first
online cpu from the range of cpus asscociated with the PMU CORE device.
It can work when pass a perf_pmu entity to get_cpuid_str. However, it
will pass NULL via perf_pmu__find_map from metricgroup.c if we want to add
metric group for arm64. When pass NULL to get_cpuid_str, it can't return
the MIDR string.
There are three methods from userspace getting MIDR string for arm64:
1. parse sysfs(/sys/devices/system/cpu/cpu?/regs/identification/midr_el1)
2. parse procfs(/proc/cpuinfo)
3. read the hwcaps(MIDR register) with getauxval(AT_HWCAP)
Perfer to select #3 as it is more simple and direct.
Signed-off-by: Joakim Zhang <qiangqing.zh...@nxp.com>
---
tools/perf/arch/arm64/util/header.c | 68 +++++++++++------------------
1 file changed, 25 insertions(+), 43 deletions(-)
diff --git a/tools/perf/arch/arm64/util/header.c
b/tools/perf/arch/arm64/util/header.c
index 534cd2507d83..f58f08af0be8 100644
--- a/tools/perf/arch/arm64/util/header.c
+++ b/tools/perf/arch/arm64/util/header.c
@@ -2,64 +2,46 @@
#include <stdlib.h>
#include <api/fs/fs.h>
#include "header.h"
+#include <asm/hwcap.h>
+#include <sys/auxv.h>
-#define MIDR "/regs/identification/midr_el1"
#define MIDR_SIZE 19
#define MIDR_REVISION_MASK 0xf
#define MIDR_VARIANT_SHIFT 20
#define MIDR_VARIANT_MASK (0xf << MIDR_VARIANT_SHIFT)
-char *get_cpuid_str(struct perf_pmu *pmu)
+#define get_cpuid(id) ({ \
+ unsigned long __val; \
+ asm("mrs %0, "#id : "=r" (__val)); \
+ __val; \
+ })
+
+char *get_cpuid_str(struct perf_pmu *pmu __maybe_unused)
{
char *buf = NULL;
- char path[PATH_MAX];
- const char *sysfs = sysfs__mountpoint();
- int cpu;
- u64 midr = 0;
- struct cpu_map *cpus;
- FILE *file;
+ unsigned long midr = 0;
- if (!sysfs || !pmu || !pmu->cpus)
+ if (!(getauxval(AT_HWCAP) & HWCAP_CPUID)) {
+ fputs("CPUID registers unavailable\n", stderr);
return NULL;
+ }
- buf = malloc(MIDR_SIZE);
- if (!buf)
+ midr = get_cpuid(MIDR_EL1);
+ if (!midr) {
+ fputs("Failed to get cpuid string\n", stderr);
return NULL;
+ }
- /* read midr from list of cpus mapped to this pmu */
- cpus = cpu_map__get(pmu->cpus);
- for (cpu = 0; cpu < cpus->nr; cpu++) {
- scnprintf(path, PATH_MAX, "%s/devices/system/cpu/cpu%d"MIDR,
- sysfs, cpus->map[cpu]);
-
- file = fopen(path, "r");
- if (!file) {
- pr_debug("fopen failed for file %s\n", path);
- continue;
- }
-
- if (!fgets(buf, MIDR_SIZE, file)) {
- fclose(file);
- continue;
- }
- fclose(file);
+ /* Ignore/clear Variant[23:20] and
+ * Revision[3:0] of MIDR
+ */
+ midr &= (~(MIDR_VARIANT_MASK | MIDR_REVISION_MASK));
- /* Ignore/clear Variant[23:20] and
- * Revision[3:0] of MIDR
- */
- midr = strtoul(buf, NULL, 16);
- midr &= (~(MIDR_VARIANT_MASK | MIDR_REVISION_MASK));
- scnprintf(buf, MIDR_SIZE, "0x%016lx", midr);
- /* got midr break loop */
- break;
- }
+ buf = malloc(MIDR_SIZE);
+ if (!buf)
+ return NULL;
- if (!midr) {
- pr_err("failed to get cpuid string for PMU %s\n", pmu->name);
- free(buf);
- buf = NULL;
- }
+ scnprintf(buf, MIDR_SIZE, "0x%016lx", midr);
- cpu_map__put(cpus);
return buf;
}
--
2.17.1
