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