On Wed, Aug 16, 2017 at 12:40:46PM +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 | 61
> +++++++++++++++++++++++++++++++++++++
> 2 files changed, 62 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..713ef17
> --- /dev/null
> +++ b/tools/perf/arch/arm64/util/header.c
> @@ -0,0 +1,61 @@
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <api/fs/fs.h>
> +#include "header.h"
> +
> +#define MIDR "/regs/identification/midr_el1"
> +#define MIDR_SIZE 128
Why is this so big?
> +char *get_cpuid_str(struct perf_pmu *pmu)
> +{
> + char *buf = NULL;
> + char *temp = NULL;
> + char path[PATH_MAX];
> + const char *sysfs = sysfs__mountpoint();
> + int cpu;
> + unsigned long long 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_err("fopen failed for file %s\n", path);
pr_debug instead? It's not fatal if a CPU is hotplugged off and you can't
read its midr.
> + continue;
> + }
> +
> + temp = fgets(buf, MIDR_SIZE, file);
> + if (!temp)
> + continue;
Do you actually need a temporary variable for this?
> + fclose(file);
> +
> + /* Ignore/clear Variant[23:20] and
> + * Revision[3:0] of MIDR
> + */
> + midr = strtoll(buf, NULL, 16);
> + midr &= (~(0xf << 20 | 0xf));
If midr really needs to be unsigned long long (u64 might be better), then
you need to fix these immediates to have a ULL suffix.
Can you use the GENMASK_ULL macro to generate the MIDR mask, or is that
not available here?
> + scnprintf(buf, MIDR_SIZE, "0x%016llx", midr);
> + /* got midr break loop */
> + break;
> + }
> +
> + if (!midr) {
> + free(buf);
> + buf = NULL;
If you want the pr_err, here would seem more appropriate because at this
point we've actually failed.
Will
