perf tools: Add arm64 version of get_cpuid()

Commit Message

John Garry Dec. 13, 2019, 1:54 p.m. UTC

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 <[e-mail]>

Comments

John Garry Jan. 7, 2020, 9:13 a.m. UTC | #1

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 <[e-mail]>
> 
> 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;
>   }
>

Shaokun Zhang Feb. 12, 2020, 9:30 a.m. UTC | #2

Hi John,

I tested this patch on my new ARM64 Kunpeng 920 server.
[root@node1 zsk]# ./perf --version
perf version 5.6.rc1.g2cdb955b7252

Both perf list and perf stat can work.

Tested-by: Shaokun Zhang <[e-mail]>

Thanks,
Shaokun

On 2019/12/13 21:54, John Garry wrote:
> 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 <[e-mail]>
> 
> 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;
>  }
>

Arnaldo Carvalho de Melo Feb. 12, 2020, 1:35 p.m. UTC | #3

Em Wed, Feb 12, 2020 at 05:30:56PM +0800, Shaokun Zhang escreveu:
> Hi John,
> 
> I tested this patch on my new ARM64 Kunpeng 920 server.
> [root@node1 zsk]# ./perf --version
> perf version 5.6.rc1.g2cdb955b7252
> 
> Both perf list and perf stat can work.
> 
> Tested-by: Shaokun Zhang <[e-mail]>

Thanks for the test and for (re)bringing this patch to my attention, I'll
process it now.

Thanks!

- Arnaldo
 
> Thanks,
> Shaokun
> 
> On 2019/12/13 21:54, John Garry wrote:
> > 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 <[e-mail]>
> > 
> > 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;
> >  }
> > 
>

Arnaldo Carvalho de Melo Feb. 12, 2020, 1:40 p.m. UTC | #4

Em Tue, Jan 07, 2020 at 09:13:43AM +0000, John Garry escreveu:
> 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?

Got lost in the holidays, devconf.cz, vacations, sorry, picking it up
now, together with a Tested-by by Shaokun Zhang, some issues with the
formatting of the patch:

- Avoid starting lines with '#' as those will vanish when I use 'git am'

- Separate the commit log message from the diff using a '---' at the
  begining of the line, otherwise 'git am' fails

I fixed those up now, will test with my build containers, thanks.

- Arnaldo
 
> 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 <[e-mail]>
> > 
> > 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;
> >   }
> > 
>

John Garry Feb. 12, 2020, 3:49 p.m. UTC | #5

On 12/02/2020 13:40, Arnaldo Carvalho de Melo wrote:
> Em Tue, Jan 07, 2020 at 09:13:43AM +0000, John Garry escreveu:
>> 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?
> 
> Got lost in the holidays, devconf.cz, vacations, sorry, picking it up
> now, together with a Tested-by by Shaokun Zhang, some issues with the
> formatting of the patch:
> 
> - Avoid starting lines with '#' as those will vanish when I use 'git am'

ah, so this must be why people use, for example, '/include "..."' in 
commit logs

> 
> - Separate the commit log message from the diff using a '---' at the
>    begining of the line, otherwise 'git am' fails

apologizes, I must have cut that by mistake

> 
> I fixed those up now, will test with my build containers, thanks.
> 

Thanks

> - Arnaldo
>   
>> 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 <[e-mail]>
>>>
>>> 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;
>>>    }
>>>
>>
>

Patch

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;
 }