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SubjectRe: [PATCH v6 2/4] perf tools arm64: Add support for get_cpuid_str function.
On Wed, Oct 11, 2017 at 5:43 PM, Will Deacon <will.deacon@arm.com> wrote:
> 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?

thanks.
>
>> +
>> + /* 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.

ok, i can add it.
I felt, it is not to required, since it is not used anywhere else and
for better code readability.

>
>> + 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.

ok, i can print name, need to check for cpu map.
>
> Will

thanks
Ganapat

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