Hello,
On Tue, Dec 15, 2020 at 10:35 AM Tiezhu Yang <[email protected]> wrote:
>
> 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]>
> ---
>
> v2: Use HAVE_DWARF_SUPPORT to check
I'm not sure whether this is because of lack of dwarf library or kernel support.
Based on the error message, I guess it's from the kernel. Then I think this
patch won't be sufficient..
Thanks,
Namhyung
>
> 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..ad08554 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"
>
> @@ -276,6 +277,7 @@ 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 +292,15 @@ 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;
> --
> 2.1.0
>
