[v2,4/8] libperf: Add support for overflow handling of sampling events

Commit Message

Charlie Jenkins July 27, 2024, 5:29 a.m. UTC

From: Shunsuke Nakamura <[e-mail]>

Extend the fields of the opts structure to set up overflow handling
for sampling events. Also, add processing to set signal handlers in
perf_evsel__open_opts.

Signed-off-by: Shunsuke Nakamura <[e-mail]>
Signed-off-by: Charlie Jenkins <[e-mail]>
---
 tools/lib/perf/Documentation/libperf.txt |  6 ++-
 tools/lib/perf/Makefile                  |  1 +
 tools/lib/perf/evsel.c                   | 79 ++++++++++++++++++++++++++++++++
 tools/lib/perf/include/perf/evsel.h      |  6 ++-
 tools/lib/perf/tests/test-evlist.c       |  1 -
 5 files changed, 90 insertions(+), 3 deletions(-)

Patch

diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt
index 83827b94617a..bb99534d5855 100644
--- a/tools/lib/perf/Documentation/libperf.txt
+++ b/tools/lib/perf/Documentation/libperf.txt
@@ -137,8 +137,12 @@  SYNOPSIS
           size_t sz;
 
           unsigned long open_flags;       /* perf_event_open flags */
+          int fcntl_flags;
+          unsigned int signal;
+          int owner_type;                 /* value for F_SETOWN_EX */
+          struct sigaction *sigact;
   };
-  #define perf_evsel_open_opts__last_field open_flags
+  #define perf_evsel_open_opts__last_field sigact
 
   #define LIBPERF_OPTS(TYPE, NAME, ...)
 
diff --git a/tools/lib/perf/Makefile b/tools/lib/perf/Makefile
index 3a9b2140aa04..9dade2ad91bd 100644
--- a/tools/lib/perf/Makefile
+++ b/tools/lib/perf/Makefile
@@ -75,6 +75,7 @@  override CFLAGS += -Werror -Wall
 override CFLAGS += -fPIC
 override CFLAGS += $(INCLUDES)
 override CFLAGS += -fvisibility=hidden
+override CFLAGS += -D_GNU_SOURCE
 
 all:
 
diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index 96ecf3e5c8b4..17d3d9a88c23 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -562,6 +562,79 @@  void perf_counts_values__scale(struct perf_counts_values *count,
 		*pscaled = scaled;
 }
 
+static int perf_evsel__run_fcntl(struct perf_evsel *evsel,
+				 unsigned int cmd, unsigned long arg,
+				 int cpu_map_idx)
+{
+	int thread;
+
+	for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
+		int err;
+		int *fd = FD(evsel, cpu_map_idx, thread);
+
+		if (!fd || *fd < 0)
+			return -1;
+
+		err = fcntl(*fd, cmd, arg);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int perf_evsel__set_signal_handler(struct perf_evsel *evsel,
+					  struct perf_evsel_open_opts *opts)
+{
+	unsigned int fcntl_flags;
+	unsigned int signal;
+	struct f_owner_ex owner;
+	struct sigaction *sigact;
+	int cpu_map_idx;
+	int err = 0;
+
+	fcntl_flags = OPTS_GET(opts, fcntl_flags, (O_RDWR | O_NONBLOCK | O_ASYNC));
+	signal = OPTS_GET(opts, signal, SIGIO);
+	owner.type = OPTS_GET(opts, owner_type, F_OWNER_PID);
+	sigact = OPTS_GET(opts, sigact, NULL);
+
+	if (fcntl_flags == 0 && signal == 0 && !owner.type == 0 && sigact == 0)
+		return err;
+
+	err = sigaction(signal, sigact, NULL);
+	if (err)
+		return err;
+
+	switch (owner.type) {
+	case F_OWNER_PID:
+		owner.pid = getpid();
+		break;
+	case F_OWNER_TID:
+		owner.pid = syscall(SYS_gettid);
+		break;
+	case F_OWNER_PGRP:
+	default:
+		return -1;
+	}
+
+	for (cpu_map_idx = 0; cpu_map_idx < xyarray__max_x(evsel->fd); cpu_map_idx++) {
+		err = perf_evsel__run_fcntl(evsel, F_SETFL, fcntl_flags, cpu_map_idx);
+		if (err)
+			return err;
+
+		err = perf_evsel__run_fcntl(evsel, F_SETSIG, signal, cpu_map_idx);
+		if (err)
+			return err;
+
+		err = perf_evsel__run_fcntl(evsel, F_SETOWN_EX,
+					    (unsigned long)&owner, cpu_map_idx);
+		if (err)
+			return err;
+	}
+
+	return err;
+}
+
 int perf_evsel__open_opts(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
 			  struct perf_thread_map *threads,
 			  struct perf_evsel_open_opts *opts)
@@ -576,6 +649,12 @@  int perf_evsel__open_opts(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
 	evsel->open_flags = OPTS_GET(opts, open_flags, 0);
 
 	err = perf_evsel__open(evsel, cpus, threads);
+	if (err)
+		return err;
+
+	err = perf_evsel__set_signal_handler(evsel, opts);
+	if (err)
+		return err;
 
 	return err;
 }
diff --git a/tools/lib/perf/include/perf/evsel.h b/tools/lib/perf/include/perf/evsel.h
index 8eb3927f3cd0..344808f23371 100644
--- a/tools/lib/perf/include/perf/evsel.h
+++ b/tools/lib/perf/include/perf/evsel.h
@@ -31,9 +31,13 @@  struct perf_evsel_open_opts {
 	size_t sz;
 
 	unsigned long open_flags;	/* perf_event_open flags */
+	int fcntl_flags;
+	int signal;
+	int owner_type;			/* value for F_SETOWN_EX */
+	struct sigaction *sigact;
 };
 
-#define perf_evsel_open_opts__last_field open_flags
+#define perf_evsel_open_opts__last_field sigact
 
 #define LIBPERF_OPTS(TYPE, NAME, ...)			\
 	struct TYPE NAME = ({				\
diff --git a/tools/lib/perf/tests/test-evlist.c b/tools/lib/perf/tests/test-evlist.c
index 10f70cb41ff1..3a833f0349d3 100644
--- a/tools/lib/perf/tests/test-evlist.c
+++ b/tools/lib/perf/tests/test-evlist.c
@@ -1,5 +1,4 @@ 
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE // needed for sched.h to get sched_[gs]etaffinity and CPU_(ZERO,SET)
 #include <inttypes.h>
 #include <sched.h>
 #include <stdio.h>