perf lock: Implement cpu and task filters for BPF

Add -a/--all-cpus and -C/--cpu options for cpu filtering.  Also -p/--pid
and --tid options are added for task filtering.  The short -t option is
taken for --threads already.  Tracking the command line workload is
possible as well.

  $ sudo perf lock contention -a -b sleep 1
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220729200756.666106-4-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-lock.txt

@@ -128,6 +128,23 @@ CONTENTION OPTIONS
 	Use BPF program to collect lock contention stats instead of
 	using the input data.
 
+-a::
+--all-cpus::
+        System-wide collection from all CPUs.
+
+-C::
+--cpu::
+	Collect samples only on the list of CPUs provided. Multiple CPUs can be
+	provided as a comma-separated list with no space: 0,1. Ranges of CPUs
+	are specified with -: 0-2.  Default is to monitor all CPUs.
+
+-p::
+--pid=::
+	Record events on existing process ID (comma separated list).
+
+--tid=::
+        Record events on existing thread ID (comma separated list).
+
 
 SEE ALSO
 --------

tools/perf/builtin-lock.c

@@ -9,6 +9,7 @@
 #include "util/symbol.h"
 #include "util/thread.h"
 #include "util/header.h"
+#include "util/target.h"
 #include "util/callchain.h"
 #include "util/lock-contention.h"
 
@@ -38,6 +39,7 @@
 #include <linux/stringify.h>
 
 static struct perf_session *session;
+static struct target target;
 
 /* based on kernel/lockdep.c */
 #define LOCKHASH_BITS		12
@@ -1578,7 +1580,7 @@ static void sighandler(int sig __maybe_unused)
 {
 }
 
-static int __cmd_contention(void)
+static int __cmd_contention(int argc, const char **argv)
 {
 	int err = -EINVAL;
 	struct perf_tool eops = {
@@ -1592,6 +1594,7 @@ static int __cmd_contention(void)
 		.mode  = PERF_DATA_MODE_READ,
 		.force = force,
 	};
+	struct evlist *evlist = NULL;
 
 	session = perf_session__new(use_bpf ? NULL : &data, &eops);
 	if (IS_ERR(session)) {
@@ -1604,14 +1607,40 @@ static int __cmd_contention(void)
 	symbol__init(&session->header.env);
 
 	if (use_bpf) {
-		if (lock_contention_prepare() < 0) {
-			pr_err("lock contention BPF setup failed\n");
-			return -1;
+		err = target__validate(&target);
+		if (err) {
+			char errbuf[512];
+
+			target__strerror(&target, err, errbuf, 512);
+			pr_err("%s\n", errbuf);
+			goto out_delete;
 		}
 
 		signal(SIGINT, sighandler);
 		signal(SIGCHLD, sighandler);
 		signal(SIGTERM, sighandler);
+
+		evlist = evlist__new();
+		if (evlist == NULL) {
+			err = -ENOMEM;
+			goto out_delete;
+		}
+
+		err = evlist__create_maps(evlist, &target);
+		if (err < 0)
+			goto out_delete;
+
+		if (argc) {
+			err = evlist__prepare_workload(evlist, &target,
+						       argv, false, NULL);
+			if (err < 0)
+				goto out_delete;
+		}
+
+		if (lock_contention_prepare(evlist, &target) < 0) {
+			pr_err("lock contention BPF setup failed\n");
+			goto out_delete;
+		}
 	} else {
 		if (!perf_session__has_traces(session, "lock record"))
 			goto out_delete;
@@ -1642,6 +1671,8 @@ static int __cmd_contention(void)
 
 	if (use_bpf) {
 		lock_contention_start();
+		if (argc)
+			evlist__start_workload(evlist);
 
 		/* wait for signal */
 		pause();
@@ -1660,6 +1691,7 @@ static int __cmd_contention(void)
 	print_contention_result();
 
 out_delete:
+	evlist__delete(evlist);
 	lock_contention_finish();
 	perf_session__delete(session);
 	return err;
@@ -1792,6 +1824,15 @@ int cmd_lock(int argc, const char **argv)
 	OPT_BOOLEAN('t', "threads", &show_thread_stats,
 		    "show per-thread lock stats"),
 	OPT_BOOLEAN('b', "use-bpf", &use_bpf, "use BPF program to collect lock contention stats"),
+	OPT_BOOLEAN('a', "all-cpus", &target.system_wide,
+		    "System-wide collection from all CPUs"),
+	OPT_STRING('C', "cpu", &target.cpu_list, "cpu",
+		    "List of cpus to monitor"),
+	OPT_STRING('p', "pid", &target.pid, "pid",
+		   "Trace on existing process id"),
+	/* TODO: Add short option -t after -t/--tracer can be removed. */
+	OPT_STRING(0, "tid", &target.tid, "tid",
+		   "Trace on existing thread id (exclusive to --pid)"),
 	OPT_PARENT(lock_options)
 	};
 
@@ -1861,12 +1902,8 @@ int cmd_lock(int argc, const char **argv)
 		if (argc) {
 			argc = parse_options(argc, argv, contention_options,
 					     contention_usage, 0);
-			if (argc) {
-				usage_with_options(contention_usage,
-						   contention_options);
-			}
 		}
-		rc = __cmd_contention();
+		rc = __cmd_contention(argc, argv);
 	} else {
 		usage_with_options(lock_usage, lock_options);
 	}

tools/perf/util/bpf_lock_contention.c

 // SPDX-License-Identifier: GPL-2.0
 #include "util/debug.h"
+#include "util/evlist.h"
 #include "util/machine.h"
 #include "util/map.h"
 #include "util/symbol.h"
+#include "util/target.h"
+#include "util/thread_map.h"
 #include "util/lock-contention.h"
 #include <linux/zalloc.h>
 #include <bpf/bpf.h>
@@ -24,19 +27,65 @@ struct lock_contention_data {
 	u32 flags;
 };
 
-int lock_contention_prepare(void)
+int lock_contention_prepare(struct evlist *evlist, struct target *target)
 {
+	int i, fd;
+	int ncpus = 1, ntasks = 1;
+
 	skel = lock_contention_bpf__open();
 	if (!skel) {
 		pr_err("Failed to open lock-contention BPF skeleton\n");
 		return -1;
 	}
 
+	if (target__has_cpu(target))
+		ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
+	if (target__has_task(target))
+		ntasks = perf_thread_map__nr(evlist->core.threads);
+
+	bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
+	bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+
 	if (lock_contention_bpf__load(skel) < 0) {
 		pr_err("Failed to load lock-contention BPF skeleton\n");
 		return -1;
 	}
 
+	if (target__has_cpu(target)) {
+		u32 cpu;
+		u8 val = 1;
+
+		skel->bss->has_cpu = 1;
+		fd = bpf_map__fd(skel->maps.cpu_filter);
+
+		for (i = 0; i < ncpus; i++) {
+			cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
+			bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
+		}
+	}
+
+	if (target__has_task(target)) {
+		u32 pid;
+		u8 val = 1;
+
+		skel->bss->has_task = 1;
+		fd = bpf_map__fd(skel->maps.task_filter);
+
+		for (i = 0; i < ntasks; i++) {
+			pid = perf_thread_map__pid(evlist->core.threads, i);
+			bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
+		}
+	}
+
+	if (target__none(target) && evlist->workload.pid > 0) {
+		u32 pid = evlist->workload.pid;
+		u8 val = 1;
+
+		skel->bss->has_task = 1;
+		fd = bpf_map__fd(skel->maps.task_filter);
+		bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
+	}
+
 	lock_contention_bpf__attach(skel);
 	return 0;
 }

tools/perf/util/bpf_skel/lock_contention.bpf.c

@@ -54,8 +54,47 @@ struct {
 	__uint(max_entries, MAX_ENTRIES);
 } lock_stat SEC(".maps");
 
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u8));
+	__uint(max_entries, 1);
+} cpu_filter SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u8));
+	__uint(max_entries, 1);
+} task_filter SEC(".maps");
+
 /* control flags */
 int enabled;
+int has_cpu;
+int has_task;
+
+static inline int can_record(void)
+{
+	if (has_cpu) {
+		__u32 cpu = bpf_get_smp_processor_id();
+		__u8 *ok;
+
+		ok = bpf_map_lookup_elem(&cpu_filter, &cpu);
+		if (!ok)
+			return 0;
+	}
+
+	if (has_task) {
+		__u8 *ok;
+		__u32 pid = bpf_get_current_pid_tgid();
+
+		ok = bpf_map_lookup_elem(&task_filter, &pid);
+		if (!ok)
+			return 0;
+	}
+
+	return 1;
+}
 
 SEC("tp_btf/contention_begin")
 int contention_begin(u64 *ctx)
@@ -63,7 +102,7 @@ int contention_begin(u64 *ctx)
 	struct task_struct *curr;
 	struct tstamp_data *pelem;
 
-	if (!enabled)
+	if (!enabled || !can_record())
 		return 0;
 
 	curr = bpf_get_current_task_btf();

tools/perf/util/lock-contention.h

@@ -103,11 +103,13 @@ struct thread_stat {
 #define LCB_F_PERCPU	(1U << 4)
 #define LCB_F_MUTEX	(1U << 5)
 
+struct evlist;
 struct machine;
+struct target;
 
 #ifdef HAVE_BPF_SKEL
 
-int lock_contention_prepare(void);
+int lock_contention_prepare(struct evlist *evlist, struct target *target);
 int lock_contention_start(void);
 int lock_contention_stop(void);
 int lock_contention_read(struct machine *machine, struct hlist_head *head);
@@ -115,7 +117,12 @@ int lock_contention_finish(void);
 
 #else  /* !HAVE_BPF_SKEL */
 
-static inline int lock_contention_prepare(void) { return 0; }
+static inline int lock_contention_prepare(struct evlist *evlist __maybe_unused,
+					  struct target *target __maybe_unused)
+{
+	return 0;
+}
+
 static inline int lock_contention_start(void) { return 0; }
 static inline int lock_contention_stop(void) { return 0; }
 static inline int lock_contention_finish(void) { return 0; }