On Thu, Jul 20, 2017 at 11:26:06AM +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.kulka...@cavium.com>
> ---
>  tools/perf/arch/arm64/util/Build    |  1 +
>  tools/perf/arch/arm64/util/header.c | 59 
> +++++++++++++++++++++++++++++++++++++
>  2 files changed, 60 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..4e25498
> --- /dev/null
> +++ b/tools/perf/arch/arm64/util/header.c
> @@ -0,0 +1,59 @@
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <api/fs/fs.h>
> +#include "header.h"
> +
> +#define MIDR "/regs/identification/midr_el1"
> +#define MIDR_SIZE 128
> +
> +char *get_cpuid_str(struct perf_pmu *pmu)
> +{
> +     char *buf = malloc(MIDR_SIZE);
> +     char *temp = NULL;
> +     char path[PATH_MAX];
> +     const char *sysfs = sysfs__mountpoint();
> +     int cpu, ret;
> +     unsigned long long midr;
> +     struct cpu_map *cpus;
> +     FILE *file;
> +
> +     if (!pmu->cpus)
> +             return NULL;
> +
> +     if (!sysfs)
> +             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++) {
> +             ret = snprintf(path, PATH_MAX,
> +                             "%s/devices/system/cpu/cpu%d"MIDR,
> +                             sysfs, cpus->map[cpu]);
> +             if (ret == PATH_MAX) {
> +                     pr_err("sysfs path crossed PATH_MAX(%d) size\n", 
> PATH_MAX);
> +                     goto err;
> +             }
> +
> +             file = fopen(path, "r");
> +             if (!file)
> +                     continue;
> +
> +             temp = fgets(buf, MIDR_SIZE, file);
> +             fclose(file);
> +             if (!temp)
> +                     continue;
> +
> +             /* Ignore/clear Variant[23:20] and
> +              * Revision[3:0] of MIDR
> +              */
> +             midr = strtoll(buf, NULL, 16);
> +             midr &= (~(0xf << 20 | 0xf));
> +             snprintf(buf, MIDR_SIZE, "0x%016llx", midr);
> +             cpu_map__put(cpus);
> +             return buf;
> +     }
> +
> +err: cpu_map__put(cpus);
> +     free(buf);
> +     return NULL;
> +}

Might just be me, but I found this really difficult to read. I think it
works, but having the return at the end of loop is really counter-intuitive.

I'll leave it up to Arnaldo, since I can't find any functional problems
with this series from the arm64 side.

Cheers,

Will

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