[PATCH 25/25] perf record: Add --buildid-mmap option to enable mmap's build id

Jiri Olsa
2020-11-26T17:02:35Z

Adding --buildid-mmap option to enable build id in mmap2 events.
It will only work if there's kernel support for that and it disables
build id cache (implies --no-buildid).

It's also possible to enable it permanently via config option
in ~.perfconfig file:

[record]
build-id=mmap

Also added build_id bit in the verbose output for perf_event_attr:

# perf record --buildid-mmap -vv
...
perf_event_attr:
type 1
size 120
...
build_id 1

Adding also missing text_poke bit.

Acked-by: Ian Rogers <irogers@google.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/perf/Documentation/perf-config.txt | 3 ++-
tools/perf/Documentation/perf-record.txt | 3 +++
tools/perf/builtin-record.c | 20 ++++++++++++++++++++
tools/perf/util/evsel.c | 10 ++++++----
tools/perf/util/perf_api_probe.c | 10 ++++++++++
tools/perf/util/perf_api_probe.h | 1 +
tools/perf/util/perf_event_attr_fprintf.c | 2 ++
tools/perf/util/record.h | 1 +
8 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
index e3672c5d801b..8a1c6c16821a 100644
--- a/tools/perf/Documentation/perf-config.txt
+++ b/tools/perf/Documentation/perf-config.txt
@@ -559,11 +559,12 @@ kmem.*::

record.*::
record.build-id::
- This option can be 'cache', 'no-cache' or 'skip'.
+ This option can be 'cache', 'no-cache', 'skip' or 'mmap'.
'cache' is to post-process data and save/update the binaries into
the build-id cache (in ~/.debug). This is the default.
But if this option is 'no-cache', it will not update the build-id cache.
'skip' skips post-processing and does not update the cache.
+ 'mmap' skips post-processing and reads build-ids from MMAP events.

record.call-graph::
This is identical to 'call-graph.record-mode', except it is
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 768888b9326a..1bcf51e24979 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -482,6 +482,9 @@ Specify vmlinux path which has debuginfo.
--buildid-all::
Record build-id of all DSOs regardless whether it's actually hit or not.

+--buildid-mmap::
+Record build ids in mmap2 events, disables build id cache (implies --no-buildid).
+
--aio[=n]::
Use <n> control blocks in asynchronous (Posix AIO) trace writing mode (default: 1, max: 4).
Asynchronous mode is supported only when linking Perf tool with libc library
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index adf311d15d3d..47bae9d82d43 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -102,6 +102,7 @@ struct record {
bool no_buildid_cache;
bool no_buildid_cache_set;
bool buildid_all;
+ bool buildid_mmap;
bool timestamp_filename;
bool timestamp_boundary;
struct switch_output switch_output;
@@ -2139,6 +2140,8 @@ static int perf_record_config(const char *var, const char *value, void *cb)
rec->no_buildid_cache = true;
else if (!strcmp(value, "skip"))
rec->no_buildid = true;
+ else if (!strcmp(value, "mmap"))
+ rec->buildid_mmap = true;
else
return -1;
return 0;
@@ -2554,6 +2557,8 @@ static struct option __record_options[] = {
"file", "vmlinux pathname"),
OPT_BOOLEAN(0, "buildid-all", &record.buildid_all,
"Record build-id of all DSOs regardless of hits"),
+ OPT_BOOLEAN(0, "buildid-mmap", &record.buildid_mmap,
+ "Record build-id in map events"),
OPT_BOOLEAN(0, "timestamp-filename", &record.timestamp_filename,
"append timestamp to output filename"),
OPT_BOOLEAN(0, "timestamp-boundary", &record.timestamp_boundary,
@@ -2657,6 +2662,21 @@ int cmd_record(int argc, const char **argv)

}

+ if (rec->buildid_mmap) {
+ if (!perf_can_record_build_id()) {
+ pr_err("Failed: no support to record build id in mmap events, update your kernel.\n");
+ err = -EINVAL;
+ goto out_opts;
+ }
+ pr_debug("Enabling build id in mmap2 events.\n");
+ /* Enable mmap build id synthesizing. */
+ symbol_conf.buildid_mmap2 = true;
+ /* Enable perf_event_attr::build_id bit. */
+ rec->opts.build_id = true;
+ /* Disable build id cache. */
+ rec->no_buildid = true;
+ }
+
if (rec->opts.kcore)
rec->data.is_dir = true;

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 1cad6051d8b0..749d806ee1d1 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1170,10 +1170,12 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
if (opts->sample_weight)
evsel__set_sample_bit(evsel, WEIGHT);

- attr->task = track;
- attr->mmap = track;
- attr->mmap2 = track && !perf_missing_features.mmap2;
- attr->comm = track;
+ attr->task = track;
+ attr->mmap = track;
+ attr->mmap2 = track && !perf_missing_features.mmap2;
+ attr->comm = track;
+ attr->build_id = track && opts->build_id;
+
/*
* ksymbol is tracked separately with text poke because it needs to be
* system wide and enabled immediately.
diff --git a/tools/perf/util/perf_api_probe.c b/tools/perf/util/perf_api_probe.c
index 3840d02f0f7b..829af17a0867 100644
--- a/tools/perf/util/perf_api_probe.c
+++ b/tools/perf/util/perf_api_probe.c
@@ -98,6 +98,11 @@ static void perf_probe_text_poke(struct evsel *evsel)
evsel->core.attr.text_poke = 1;
}

+static void perf_probe_build_id(struct evsel *evsel)
+{
+ evsel->core.attr.build_id = 1;
+}
+
bool perf_can_sample_identifier(void)
{
return perf_probe_api(perf_probe_sample_identifier);
@@ -172,3 +177,8 @@ bool perf_can_aux_sample(void)

return true;
}
+
+bool perf_can_record_build_id(void)
+{
+ return perf_probe_api(perf_probe_build_id);
+}
diff --git a/tools/perf/util/perf_api_probe.h b/tools/perf/util/perf_api_probe.h
index d5506a983a94..f12ca55f509a 100644
--- a/tools/perf/util/perf_api_probe.h
+++ b/tools/perf/util/perf_api_probe.h
@@ -11,5 +11,6 @@ bool perf_can_record_cpu_wide(void);
bool perf_can_record_switch_events(void);
bool perf_can_record_text_poke_events(void);
bool perf_can_sample_identifier(void);
+bool perf_can_record_build_id(void);

#endif // __PERF_API_PROBE_H
diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
index e67a227c0ce7..656a7fddfc26 100644
--- a/tools/perf/util/perf_event_attr_fprintf.c
+++ b/tools/perf/util/perf_event_attr_fprintf.c
@@ -134,6 +134,8 @@ int perf_event_attr__fprintf(FILE *fp, struct perf_event_attr *attr,
PRINT_ATTRf(bpf_event, p_unsigned);
PRINT_ATTRf(aux_output, p_unsigned);
PRINT_ATTRf(cgroup, p_unsigned);
+ PRINT_ATTRf(text_poke, p_unsigned);
+ PRINT_ATTRf(build_id, p_unsigned);

PRINT_ATTRn("{ wakeup_events, wakeup_watermark }", wakeup_events, p_unsigned);
PRINT_ATTRf(bp_type, p_unsigned);
diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index 266760ac9143..609e706f4282 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -49,6 +49,7 @@ struct record_opts {
bool no_bpf_event;
bool kcore;
bool text_poke;
+ bool build_id;
unsigned int freq;
unsigned int mmap_pages;
unsigned int auxtrace_mmap_pages;
--
2.26.2