[PATCH 35/63] perf trace: Allow specifying a set of events to add in perfconfig

Arnaldo Carvalho de Melo
2018-12-18T22:13:00Z

To add augmented_raw_syscalls to the events speficied by the user, or be
the only one if no events were specified by the user, one can add this
to perfconfig:

# cat ~/.perfconfig
[trace]
add_events = /home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.o
#

I.e. pre-compile the augmented_raw_syscalls.c BPF program and make it
always load, this way:

# perf trace -e open* cat /etc/passwd > /dev/null
0.000 ( 0.013 ms): cat/31557 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
0.035 ( 0.007 ms): cat/31557 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3
0.353 ( 0.009 ms): cat/31557 openat(dfd: CWD, filename: /usr/lib/locale/locale-archive, flags: CLOEXEC) = 3
0.424 ( 0.006 ms): cat/31557 openat(dfd: CWD, filename: /etc/passwd) = 3
#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-0lgj7vh64hg3ce44gsmvj7ud@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-config.txt | 8 ++++++++
tools/perf/builtin-trace.c | 20 ++++++++++++++++++++
2 files changed, 28 insertions(+)

diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
index 661b1fb3f8ba..423cb41f6e3f 100644
--- a/tools/perf/Documentation/perf-config.txt
+++ b/tools/perf/Documentation/perf-config.txt
@@ -521,6 +521,14 @@ diff.*::
Possible values are 'delta', 'delta-abs', 'ratio' and
'wdiff'. Default is 'delta'.

+trace.*::
+ trace.add_events::
+ Allows adding a set of events to add to the ones specified
+ by the user, or use as a default one if none was specified.
+ The initial use case is to add augmented_raw_syscalls.o to
+ activate the 'perf trace' logic that looks for syscall
+ pointer contents after the normal tracepoint payload.
+
SEE ALSO
--------
linkperf:perf[1]
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 096380e8c213..d754a74aef46 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -22,6 +22,7 @@
#include "builtin.h"
#include "util/cgroup.h"
#include "util/color.h"
+#include "util/config.h"
#include "util/debug.h"
#include "util/env.h"
#include "util/event.h"
@@ -3523,6 +3524,21 @@ static void trace__set_bpf_map_syscalls(struct trace *trace)
trace->syscalls.map = bpf__find_map_by_name("syscalls");
}

+static int trace__config(const char *var, const char *value, void *arg)
+{
+ int err = 0;
+
+ if (!strcmp(var, "trace.add_events")) {
+ struct trace *trace = arg;
+ struct option o = OPT_CALLBACK('e', "event", &trace->evlist, "event",
+ "event selector. use 'perf list' to list available events",
+ parse_events_option);
+ err = parse_events_option(&o, value, 0);
+ }
+
+ return err;
+}
+
int cmd_trace(int argc, const char **argv)
{
const char *trace_usage[] = {
@@ -3645,6 +3661,10 @@ int cmd_trace(int argc, const char **argv)
goto out;
}

+ err = perf_config(trace__config, &trace);
+ if (err)
+ goto out;
+
argc = parse_options_subcommand(argc, argv, trace_options, trace_subcommands,
trace_usage, PARSE_OPT_STOP_AT_NON_OPTION);

--
2.19.2