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SubjectRe: [PATCH v6 2/4] perf tools arm64: Add support for get_cpuid_str function.
On Thu, Aug 24, 2017 at 05:33:47PM +0530, Ganapatrao Kulkarni wrote:
> function get_cpuid_str returns MIDR string of the first online
> cpu from the range of cpus associated with the pmu core device.
>
> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
> ---
> tools/perf/arch/arm64/util/Build | 1 +
> tools/perf/arch/arm64/util/header.c | 60 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 61 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..f02a32e
> --- /dev/null
> +++ b/tools/perf/arch/arm64/util/header.c
> @@ -0,0 +1,60 @@
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <api/fs/fs.h>
> +#include "header.h"
> +
> +#define MIDR "/regs/identification/midr_el1"
> +#define MIDR_SIZE 19
> +
> +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->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))
> + continue;
> + fclose(file);

Don't you want to fclose the file if the fgets fails?

> +
> + /* Ignore/clear Variant[23:20] and
> + * Revision[3:0] of MIDR
> + */
> + midr = strtoul(buf, NULL, 16);
> + midr &= (~(0xf << 20 | 0xf));

It would be cleaner if you had #defines for the MIDR fields that you're
masking.

> + scnprintf(buf, MIDR_SIZE, "0x%016lx", midr);
> + /* got midr break loop */
> + break;
> + }
> +
> + if (!midr) {
> + pr_err("failed to get cpuid string\n");

Might be helpful to print the PMU name and the CPU map if there's a way
to do that.

Will

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