Messages in this thread | | | From | Namhyung Kim <> | Date | Tue, 15 Dec 2020 22:49:59 +0900 | Subject | Re: [PATCH v2] perf callchain: Return directly when use '--call-graph dwarf' under !HAVE_DWARF_SUPPORT |
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Hello,
On Tue, Dec 15, 2020 at 10:35 AM Tiezhu Yang <yangtiezhu@loongson.cn> 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 <yangtiezhu@loongson.cn> > --- > > 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 >
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