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From:   John Garry <john.garry@huawei.com>
Subject: Re: [PATCH] perf tools: Add arm64 version of get_cpuid()
To:     <peterz@infradead.org>, <mingo@redhat.com>, <acme@kernel.org>,
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Date:   Tue, 7 Jan 2020 09:13:43 +0000
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On 13/12/2019 13:54, John Garry wrote:

Hi Arnaldo,

Do we need some reviews on this? Or was it missed/still catching up?

Cheers,
John

> Add an arm64 version of get_cpuid(), which is used for various annotation
> and headers - for example, I now get the CPUID in "perf report --header",
> as shown in this snippet:
> 
> # hostname : ubuntu
> # os release : 5.5.0-rc1-dirty
> # perf version : 5.5.rc1.gbf8a13dc9851
> # arch : aarch64
> # nrcpus online : 96
> # nrcpus avail : 96
> # cpuid : 0x00000000480fd010
> 
> Since much of the code to read the MIDR is already in get_cpuid_str(),
> factor out this code.
> 
> Signed-off-by: John Garry <john.garry@huawei.com>
> 
> diff --git a/tools/perf/arch/arm64/util/header.c b/tools/perf/arch/arm64/util/header.c
> index a32e4b72a98f..d730666ab95d 100644
> --- a/tools/perf/arch/arm64/util/header.c
> +++ b/tools/perf/arch/arm64/util/header.c
> @@ -1,8 +1,10 @@
>   #include <stdio.h>
>   #include <stdlib.h>
>   #include <perf/cpumap.h>
> +#include <util/cpumap.h>
>   #include <internal/cpumap.h>
>   #include <api/fs/fs.h>
> +#include <errno.h>
>   #include "debug.h"
>   #include "header.h"
>   
> @@ -12,26 +14,21 @@
>   #define MIDR_VARIANT_SHIFT      20
>   #define MIDR_VARIANT_MASK       (0xf << MIDR_VARIANT_SHIFT)
>   
> -char *get_cpuid_str(struct perf_pmu *pmu)
> +static int _get_cpuid(char *buf, size_t sz, struct perf_cpu_map *cpus)
>   {
> -	char *buf = NULL;
> -	char path[PATH_MAX];
>   	const char *sysfs = sysfs__mountpoint();
> -	int cpu;
>   	u64 midr = 0;
> -	struct perf_cpu_map *cpus;
> -	FILE *file;
> +	int cpu;
>   
> -	if (!sysfs || !pmu || !pmu->cpus)
> -		return NULL;
> +	if (!sysfs || sz < MIDR_SIZE)
> +		return EINVAL;
>   
> -	buf = malloc(MIDR_SIZE);
> -	if (!buf)
> -		return NULL;
> +	cpus = perf_cpu_map__get(cpus);
>   
> -	/* read midr from list of cpus mapped to this pmu */
> -	cpus = perf_cpu_map__get(pmu->cpus);
>   	for (cpu = 0; cpu < perf_cpu_map__nr(cpus); cpu++) {
> +		char path[PATH_MAX];
> +		FILE *file;
> +
>   		scnprintf(path, PATH_MAX, "%s/devices/system/cpu/cpu%d"MIDR,
>   				sysfs, cpus->map[cpu]);
>   
> @@ -57,12 +54,48 @@ char *get_cpuid_str(struct perf_pmu *pmu)
>   		break;
>   	}
>   
> -	if (!midr) {
> +	perf_cpu_map__put(cpus);
> +
> +	if (!midr)
> +		return EINVAL;
> +
> +	return 0;
> +}
> +
> +int get_cpuid(char *buf, size_t sz)
> +{
> +	struct perf_cpu_map *cpus = perf_cpu_map__new(NULL);
> +	int ret;
> +
> +	if (!cpus)
> +		return EINVAL;
> +
> +	ret = _get_cpuid(buf, sz, cpus);
> +
> +	perf_cpu_map__put(cpus);
> +
> +	return ret;
> +}
> +
> +char *get_cpuid_str(struct perf_pmu *pmu)
> +{
> +	char *buf = NULL;
> +	int res;
> +
> +	if (!pmu || !pmu->cpus)
> +		return NULL;
> +
> +	buf = malloc(MIDR_SIZE);
> +	if (!buf)
> +		return NULL;
> +
> +	/* read midr from list of cpus mapped to this pmu */
> +	res = _get_cpuid(buf, MIDR_SIZE, pmu->cpus);
> +	if (res) {
>   		pr_err("failed to get cpuid string for PMU %s\n", pmu->name);
>   		free(buf);
>   		buf = NULL;
>   	}
>   
> -	perf_cpu_map__put(cpus);
>   	return buf;
>   }
>