[PATCH v9 2/5] perf tools arm64: Add support for get_cpuid_str function.

Ganapatrao Kulkarni
2017-10-16T18:33:09Z

function get_cpuid_str returns MIDR string of the first online
cpu from the range of cpus associated with the PMU CORE device.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
---
tools/perf/arch/arm64/util/Build | 1 +
tools/perf/arch/arm64/util/header.c | 65 +++++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)
create mode 100644 tools/perf/arch/arm64/util/header.c

diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build
index cef6fb3..b1ab72d 100644
--- a/tools/perf/arch/arm64/util/Build
+++ b/tools/perf/arch/arm64/util/Build
@@ -1,3 +1,4 @@
+libperf-y += header.o
libperf-$(CONFIG_DWARF) += dwarf-regs.o
libperf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.o

diff --git a/tools/perf/arch/arm64/util/header.c b/tools/perf/arch/arm64/util/header.c
new file mode 100644
index 0000000..534cd25
--- /dev/null
+++ b/tools/perf/arch/arm64/util/header.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <api/fs/fs.h>
+#include "header.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)
+{
+ char *buf = NULL;
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+ int cpu;
+ u64 midr = 0;
+ struct cpu_map *cpus;
+ FILE *file;
+
+ if (!sysfs || !pmu || !pmu->cpus)
+ return NULL;
+
+ buf = malloc(MIDR_SIZE);
+ if (!buf)
+ 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 = strtoul(buf, NULL, 16);
+ midr &= (~(MIDR_VARIANT_MASK | MIDR_REVISION_MASK));
+ scnprintf(buf, MIDR_SIZE, "0x%016lx", midr);
+ /* got midr break loop */
+ break;
+ }
+
+ if (!midr) {
+ pr_err("failed to get cpuid string for PMU %s\n", pmu->name);
+ free(buf);
+ buf = NULL;
+ }
+
+ cpu_map__put(cpus);
+ return buf;
+}
--
2.9.4