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

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

[Tiezhu Yang]

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 <yangtiezhu@loongson.cn>
---
 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

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

[Arnaldo Carvalho de Melo]

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 <yangtiezhu@loongson.cn>
> ---
>  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

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

[Tiezhu Yang]

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 <yangtiezhu@loongson.cn>
>> ---
>>   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
>>