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Subject[PATCH 21/38] perf tools: Support for DWARF mode callchain
Date
From: Jiri Olsa <jolsa@redhat.com>

This patch enables perf to use the DWARF unwind code.

It extends the perf record '-g' option with following arguments:
'fp' - provides framepointer based user
stack backtrace
'dwarf[,size]' - provides DWARF (libunwind) based user stack
backtrace. The size specifies the size of the
user stack dump. If omitted it is 8192 by default.

If libunwind is found during the perf build, then the 'dwarf' argument
becomes available for record command. The 'fp' stays as default option
in any case.

Examples: (perf compiled with libunwind)

perf record -g dwarf ls
- provides dwarf unwind with 8192 as stack dump size

perf record -g dwarf,4096 ls
- provides dwarf unwind with 4096 as stack dump size

perf record -g -- ls
perf record -g fp ls
- provides frame pointer unwind

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Original-patch-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Arun Sharma <asharma@fb.com>
Cc: Benjamin Redelings <benjamin.redelings@nescent.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Ulrich Drepper <drepper@gmail.com>
Link: http://lkml.kernel.org/r/1344345647-11536-13-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-record.c | 114 ++++++++++++++++++++++++++++++++++++++++++-
tools/perf/perf.h | 9 +++-
tools/perf/util/evsel.c | 13 +++++-
3 files changed, 132 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4db6e1b..22dd05d 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -31,6 +31,15 @@
#include <sched.h>
#include <sys/mman.h>

+#define CALLCHAIN_HELP "do call-graph (stack chain/backtrace) recording: "
+
+#ifdef NO_LIBUNWIND_SUPPORT
+static char callchain_help[] = CALLCHAIN_HELP "[fp]";
+#else
+static unsigned long default_stack_dump_size = 8192;
+static char callchain_help[] = CALLCHAIN_HELP "[fp] dwarf";
+#endif
+
enum write_mode_t {
WRITE_FORCE,
WRITE_APPEND
@@ -732,6 +741,106 @@ error:
return ret;
}

+#ifndef NO_LIBUNWIND_SUPPORT
+static int get_stack_size(char *str, unsigned long *_size)
+{
+ char *endptr;
+ unsigned long size;
+ unsigned long max_size = round_down(USHRT_MAX, sizeof(u64));
+
+ size = strtoul(str, &endptr, 0);
+
+ do {
+ if (*endptr)
+ break;
+
+ size = round_up(size, sizeof(u64));
+ if (!size || size > max_size)
+ break;
+
+ *_size = size;
+ return 0;
+
+ } while (0);
+
+ pr_err("callchain: Incorrect stack dump size (max %ld): %s\n",
+ max_size, str);
+ return -1;
+}
+#endif /* !NO_LIBUNWIND_SUPPORT */
+
+static int
+parse_callchain_opt(const struct option *opt __used, const char *arg,
+ int unset)
+{
+ struct perf_record *rec = (struct perf_record *)opt->value;
+ char *tok, *name, *saveptr = NULL;
+ char *buf;
+ int ret = -1;
+
+ /* --no-call-graph */
+ if (unset)
+ return 0;
+
+ /* We specified default option if none is provided. */
+ BUG_ON(!arg);
+
+ /* We need buffer that we know we can write to. */
+ buf = malloc(strlen(arg) + 1);
+ if (!buf)
+ return -ENOMEM;
+
+ strcpy(buf, arg);
+
+ tok = strtok_r((char *)buf, ",", &saveptr);
+ name = tok ? : (char *)buf;
+
+ do {
+ /* Framepointer style */
+ if (!strncmp(name, "fp", sizeof("fp"))) {
+ if (!strtok_r(NULL, ",", &saveptr)) {
+ rec->opts.call_graph = CALLCHAIN_FP;
+ ret = 0;
+ } else
+ pr_err("callchain: No more arguments "
+ "needed for -g fp\n");
+ break;
+
+#ifndef NO_LIBUNWIND_SUPPORT
+ /* Dwarf style */
+ } else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
+ ret = 0;
+ rec->opts.call_graph = CALLCHAIN_DWARF;
+ rec->opts.stack_dump_size = default_stack_dump_size;
+
+ tok = strtok_r(NULL, ",", &saveptr);
+ if (tok) {
+ unsigned long size = 0;
+
+ ret = get_stack_size(tok, &size);
+ rec->opts.stack_dump_size = size;
+ }
+
+ if (!ret)
+ pr_debug("callchain: stack dump size %d\n",
+ rec->opts.stack_dump_size);
+#endif /* !NO_LIBUNWIND_SUPPORT */
+ } else {
+ pr_err("callchain: Unknown -g option "
+ "value: %s\n", arg);
+ break;
+ }
+
+ } while (0);
+
+ free(buf);
+
+ if (!ret)
+ pr_debug("callchain: type %d\n", rec->opts.call_graph);
+
+ return ret;
+}
+
static const char * const record_usage[] = {
"perf record [<options>] [<command>]",
"perf record [<options>] -- <command> [<options>]",
@@ -803,8 +912,9 @@ const struct option record_options[] = {
"number of mmap data pages"),
OPT_BOOLEAN(0, "group", &record.opts.group,
"put the counters into a counter group"),
- OPT_BOOLEAN('g', "call-graph", &record.opts.call_graph,
- "do call-graph (stack chain/backtrace) recording"),
+ OPT_CALLBACK_DEFAULT('g', "call-graph", &record, "mode[,dump_size]",
+ callchain_help, &parse_callchain_opt,
+ "fp"),
OPT_INCR('v', "verbose", &verbose,
"be more verbose (show counter open errors, etc)"),
OPT_BOOLEAN('q', "quiet", &quiet, "don't print any message"),
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index f960ccb..87f4ec6 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -209,9 +209,15 @@ void pthread__unblock_sigwinch(void);

#include "util/target.h"

+enum perf_call_graph_mode {
+ CALLCHAIN_NONE,
+ CALLCHAIN_FP,
+ CALLCHAIN_DWARF
+};
+
struct perf_record_opts {
struct perf_target target;
- bool call_graph;
+ int call_graph;
bool group;
bool inherit_stat;
bool no_delay;
@@ -230,6 +236,7 @@ struct perf_record_opts {
u64 branch_stack;
u64 default_interval;
u64 user_interval;
+ u16 stack_dump_size;
};

#endif
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index a2da682..9c54e8f 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -17,6 +17,8 @@
#include "thread_map.h"
#include "target.h"
#include "../../../include/linux/hw_breakpoint.h"
+#include "../../include/linux/perf_event.h"
+#include "perf_regs.h"

#define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
#define GROUP_FD(group_fd, cpu) (*(int *)xyarray__entry(group_fd, cpu, 0))
@@ -368,9 +370,18 @@ void perf_evsel__config(struct perf_evsel *evsel, struct perf_record_opts *opts,
attr->mmap_data = track;
}

- if (opts->call_graph)
+ if (opts->call_graph) {
attr->sample_type |= PERF_SAMPLE_CALLCHAIN;

+ if (opts->call_graph == CALLCHAIN_DWARF) {
+ attr->sample_type |= PERF_SAMPLE_REGS_USER |
+ PERF_SAMPLE_STACK_USER;
+ attr->sample_regs_user = PERF_REGS_MASK;
+ attr->sample_stack_user = opts->stack_dump_size;
+ attr->exclude_callchain_user = 1;
+ }
+ }
+
if (perf_target__has_cpu(&opts->target))
attr->sample_type |= PERF_SAMPLE_CPU;

--
1.7.1


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