2020-12-14 14:53:52

by Tiezhu Yang

Subject: [PATCH] perf callchain: Return directly when use '--call-graph dwarf' under !CONFIG_DWARF

DWARF register mappings have not been defined for some architectures,
at least for mips, so we can print an error message and then return
directly when use '--call-graph dwarf'.

E.g. without this patch:

[root@linux perf]# ./perf record --call-graph dwarf cd
Error:
The sys_perf_event_open() syscall returned with 89 (Function not implemented) for event (cycles).
/bin/dmesg | grep -i perf may provide additional information.

With this patch:

[root@linux perf]# ./perf record --call-graph dwarf cd
DWARF is not supported for architecture mips64

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

--call-graph <record_mode[,record_size]>
setup and enables call-graph (stack chain/backtrace):

record_mode: call graph recording mode (fp|dwarf|lbr)
record_size: if record_mode is 'dwarf', max size of stack recording (<bytes>)
default: 8192 (bytes)

Default: fp

Signed-off-by: Tiezhu Yang <[email protected]>
---
tools/perf/util/callchain.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 1b60985..a8cf456 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -18,6 +18,7 @@
#include <math.h>
#include <linux/string.h>
#include <linux/zalloc.h>
+#include <sys/utsname.h>

#include "asm/bug.h"

@@ -278,6 +279,16 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
} else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
const unsigned long default_stack_dump_size = 8192;

+ if (system("grep -q 'CONFIG_DWARF=y' .config-detected") != 0) {
+ struct utsname uts;
+
+ ret = uname(&uts);
+ pr_err("DWARF is not supported for architecture %s\n",
+ ret ? "unknown" : uts.machine);
+
+ return -ENOTSUP;
+ }
+
ret = 0;
param->record_mode = CALLCHAIN_DWARF;
param->dump_size = default_stack_dump_size;
--
2.1.0

2020-12-14 23:36:08

by Arnaldo Carvalho de Melo

Subject: Re: [PATCH] perf callchain: Return directly when use '--call-graph dwarf' under !CONFIG_DWARF

Em Mon, Dec 14, 2020 at 08:56:55PM +0800, Tiezhu Yang escreveu:
> DWARF register mappings have not been defined for some architectures,
> at least for mips, so we can print an error message and then return
> directly when use '--call-graph dwarf'.
>
> E.g. without this patch:
>
> [root@linux perf]# ./perf record --call-graph dwarf cd
> Error:
> The sys_perf_event_open() syscall returned with 89 (Function not implemented) for event (cycles).
> /bin/dmesg | grep -i perf may provide additional information.
>
> With this patch:
>
> [root@linux perf]# ./perf record --call-graph dwarf cd
> DWARF is not supported for architecture mips64

Good improvement on the message! But that .config-detected file isn't
available at run time, take a look if this isn't a better alternative:

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 1b60985690bba313..125178fd17482513 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -276,6 +276,7 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)

/* Dwarf style */
} else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
+#ifdef HAVE_DWARF_SUPPORT
const unsigned long default_stack_dump_size = 8192;

ret = 0;
@@ -290,6 +291,15 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
ret = get_stack_size(tok, &size);
param->dump_size = size;
}
+#else
+ struct utsname uts;
+
+ ret = uname(&uts);
+ pr_err("DWARF is not supported for architecture %s\n",
+ ret ? "unknown" : uts.machine);
+
+ return -ENOTSUP;
+#endif
} else if (!strncmp(name, "lbr", sizeof("lbr"))) {
if (!strtok_r(NULL, ",", &saveptr)) {
param->record_mode = CALLCHAIN_LBR;


> Usage: perf record [<options>] [<command>]
> or: perf record [<options>] -- <command> [<options>]
>
> --call-graph <record_mode[,record_size]>
> setup and enables call-graph (stack chain/backtrace):
>
> record_mode: call graph recording mode (fp|dwarf|lbr)
> record_size: if record_mode is 'dwarf', max size of stack recording (<bytes>)
> default: 8192 (bytes)
>
> Default: fp
>
> Signed-off-by: Tiezhu Yang <[email protected]>
> ---
> tools/perf/util/callchain.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index 1b60985..a8cf456 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -18,6 +18,7 @@
> #include <math.h>
> #include <linux/string.h>
> #include <linux/zalloc.h>
> +#include <sys/utsname.h>
>
> #include "asm/bug.h"
>
> @@ -278,6 +279,16 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
> } else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
> const unsigned long default_stack_dump_size = 8192;
>
> + if (system("grep -q 'CONFIG_DWARF=y' .config-detected") != 0) {
> + struct utsname uts;
> +
> + ret = uname(&uts);
> + pr_err("DWARF is not supported for architecture %s\n",
> + ret ? "unknown" : uts.machine);
> +
> + return -ENOTSUP;
> + }
> +
> ret = 0;
> param->record_mode = CALLCHAIN_DWARF;
> param->dump_size = default_stack_dump_size;
> --
> 2.1.0
>

--

- Arnaldo

2020-12-15 02:20:39

by Tiezhu Yang

Subject: Re: [PATCH] perf callchain: Return directly when use '--call-graph dwarf' under !CONFIG_DWARF

On 12/14/2020 09:39 PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Dec 14, 2020 at 08:56:55PM +0800, Tiezhu Yang escreveu:
>> DWARF register mappings have not been defined for some architectures,
>> at least for mips, so we can print an error message and then return
>> directly when use '--call-graph dwarf'.
>>
>> E.g. without this patch:
>>
>> [root@linux perf]# ./perf record --call-graph dwarf cd
>> Error:
>> The sys_perf_event_open() syscall returned with 89 (Function not implemented) for event (cycles).
>> /bin/dmesg | grep -i perf may provide additional information.
>>
>> With this patch:
>>
>> [root@linux perf]# ./perf record --call-graph dwarf cd
>> DWARF is not supported for architecture mips64
> Good improvement on the message! But that .config-detected file isn't
> available at run time, take a look if this isn't a better alternative:

Hi Arnaldo,

Thank you very much, the following code with #ifdef HAVE_DWARF_SUPPORT
looks good and it works well on the x86 and mips arch.

So I will send a v2 patch as soon as possible.

Thanks,
Tiezhu

>
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index 1b60985690bba313..125178fd17482513 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -276,6 +276,7 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
>
> /* Dwarf style */
> } else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
> +#ifdef HAVE_DWARF_SUPPORT
> const unsigned long default_stack_dump_size = 8192;
>
> ret = 0;
> @@ -290,6 +291,15 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
> ret = get_stack_size(tok, &size);
> param->dump_size = size;
> }
> +#else
> + struct utsname uts;
> +
> + ret = uname(&uts);
> + pr_err("DWARF is not supported for architecture %s\n",
> + ret ? "unknown" : uts.machine);
> +
> + return -ENOTSUP;
> +#endif
> } else if (!strncmp(name, "lbr", sizeof("lbr"))) {
> if (!strtok_r(NULL, ",", &saveptr)) {
> param->record_mode = CALLCHAIN_LBR;
>
>
>> Usage: perf record [<options>] [<command>]
>> or: perf record [<options>] -- <command> [<options>]
>>
>> --call-graph <record_mode[,record_size]>
>> setup and enables call-graph (stack chain/backtrace):
>>
>> record_mode: call graph recording mode (fp|dwarf|lbr)
>> record_size: if record_mode is 'dwarf', max size of stack recording (<bytes>)
>> default: 8192 (bytes)
>>
>> Default: fp
>>
>> Signed-off-by: Tiezhu Yang <[email protected]>
>> ---
>> tools/perf/util/callchain.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
>> index 1b60985..a8cf456 100644
>> --- a/tools/perf/util/callchain.c
>> +++ b/tools/perf/util/callchain.c
>> @@ -18,6 +18,7 @@
>> #include <math.h>
>> #include <linux/string.h>
>> #include <linux/zalloc.h>
>> +#include <sys/utsname.h>
>>
>> #include "asm/bug.h"
>>
>> @@ -278,6 +279,16 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
>> } else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
>> const unsigned long default_stack_dump_size = 8192;
>>
>> + if (system("grep -q 'CONFIG_DWARF=y' .config-detected") != 0) {
>> + struct utsname uts;
>> +
>> + ret = uname(&uts);
>> + pr_err("DWARF is not supported for architecture %s\n",
>> + ret ? "unknown" : uts.machine);
>> +
>> + return -ENOTSUP;
>> + }
>> +
>> ret = 0;
>> param->record_mode = CALLCHAIN_DWARF;
>> param->dump_size = default_stack_dump_size;
>> --
>> 2.1.0
>>