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