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
