1 files changed, 392 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
new file mode 100644
index 000000000000..c257813e674e
--- /dev/null
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -0,0 +1,392 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "util/bpf_counter.h"
+#include "util/debug.h"
+#include "util/evsel.h"
+#include "util/evlist.h"
+#include "util/off_cpu.h"
+#include "util/perf-hooks.h"
+#include "util/record.h"
+#include "util/session.h"
+#include "util/target.h"
+#include "util/cpumap.h"
+#include "util/thread_map.h"
+#include "util/cgroup.h"
+#include "util/strlist.h"
+#include <bpf/bpf.h>
+
+#include "bpf_skel/off_cpu.skel.h"
+
+#define MAX_STACKS  32
+#define MAX_PROC  4096
+/* we don't need actual timestamp, just want to put the samples at last */
+#define OFF_CPU_TIMESTAMP  (~0ull << 32)
+
+static struct off_cpu_bpf *skel;
+
+struct off_cpu_key {
+	u32 pid;
+	u32 tgid;
+	u32 stack_id;
+	u32 state;
+	u64 cgroup_id;
+};
+
+union off_cpu_data {
+	struct perf_event_header hdr;
+	u64 array[1024 / sizeof(u64)];
+};
+
+static int off_cpu_config(struct evlist *evlist)
+{
+	struct evsel *evsel;
+	struct perf_event_attr attr = {
+		.type	= PERF_TYPE_SOFTWARE,
+		.config = PERF_COUNT_SW_BPF_OUTPUT,
+		.size	= sizeof(attr), /* to capture ABI version */
+	};
+	char *evname = strdup(OFFCPU_EVENT);
+
+	if (evname == NULL)
+		return -ENOMEM;
+
+	evsel = evsel__new(&attr);
+	if (!evsel) {
+		free(evname);
+		return -ENOMEM;
+	}
+
+	evsel->core.attr.freq = 1;
+	evsel->core.attr.sample_period = 1;
+	/* off-cpu analysis depends on stack trace */
+	evsel->core.attr.sample_type = PERF_SAMPLE_CALLCHAIN;
+
+	evlist__add(evlist, evsel);
+
+	free(evsel->name);
+	evsel->name = evname;
+
+	return 0;
+}
+
+static void off_cpu_start(void *arg)
+{
+	struct evlist *evlist = arg;
+
+	/* update task filter for the given workload */
+	if (!skel->bss->has_cpu && !skel->bss->has_task &&
+	    perf_thread_map__pid(evlist->core.threads, 0) != -1) {
+		int fd;
+		u32 pid;
+		u8 val = 1;
+
+		skel->bss->has_task = 1;
+		skel->bss->uses_tgid = 1;
+		fd = bpf_map__fd(skel->maps.task_filter);
+		pid = perf_thread_map__pid(evlist->core.threads, 0);
+		bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
+	}
+
+	skel->bss->enabled = 1;
+}
+
+static void off_cpu_finish(void *arg __maybe_unused)
+{
+	skel->bss->enabled = 0;
+	off_cpu_bpf__destroy(skel);
+}
+
+/* v5.18 kernel added prev_state arg, so it needs to check the signature */
+static void check_sched_switch_args(void)
+{
+	const struct btf *btf = bpf_object__btf(skel->obj);
+	const struct btf_type *t1, *t2, *t3;
+	u32 type_id;
+
+	type_id = btf__find_by_name_kind(btf, "bpf_trace_sched_switch",
+					 BTF_KIND_TYPEDEF);
+	if ((s32)type_id < 0)
+		return;
+
+	t1 = btf__type_by_id(btf, type_id);
+	if (t1 == NULL)
+		return;
+
+	t2 = btf__type_by_id(btf, t1->type);
+	if (t2 == NULL || !btf_is_ptr(t2))
+		return;
+
+	t3 = btf__type_by_id(btf, t2->type);
+	if (t3 && btf_is_func_proto(t3) && btf_vlen(t3) == 4) {
+		/* new format: pass prev_state as 4th arg */
+		skel->rodata->has_prev_state = true;
+	}
+}
+
+int off_cpu_prepare(struct evlist *evlist, struct target *target,
+		    struct record_opts *opts)
+{
+	int err, fd, i;
+	int ncpus = 1, ntasks = 1, ncgrps = 1;
+	struct strlist *pid_slist = NULL;
+	struct str_node *pos;
+
+	if (off_cpu_config(evlist) < 0) {
+		pr_err("Failed to config off-cpu BPF event\n");
+		return -1;
+	}
+
+	skel = off_cpu_bpf__open();
+	if (!skel) {
+		pr_err("Failed to open off-cpu BPF skeleton\n");
+		return -1;
+	}
+
+	/* don't need to set cpu filter for system-wide mode */
+	if (target->cpu_list) {
+		ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
+		bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
+	}
+
+	if (target->pid) {
+		pid_slist = strlist__new(target->pid, NULL);
+		if (!pid_slist) {
+			pr_err("Failed to create a strlist for pid\n");
+			return -1;
+		}
+
+		ntasks = 0;
+		strlist__for_each_entry(pos, pid_slist) {
+			char *end_ptr;
+			int pid = strtol(pos->s, &end_ptr, 10);
+
+			if (pid == INT_MIN || pid == INT_MAX ||
+			    (*end_ptr != '\0' && *end_ptr != ','))
+				continue;
+
+			ntasks++;
+		}
+
+		if (ntasks < MAX_PROC)
+			ntasks = MAX_PROC;
+
+		bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+	} else if (target__has_task(target)) {
+		ntasks = perf_thread_map__nr(evlist->core.threads);
+		bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+	} else if (target__none(target)) {
+		bpf_map__set_max_entries(skel->maps.task_filter, MAX_PROC);
+	}
+
+	if (evlist__first(evlist)->cgrp) {
+		ncgrps = evlist->core.nr_entries - 1; /* excluding a dummy */
+		bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps);
+
+		if (!cgroup_is_v2("perf_event"))
+			skel->rodata->uses_cgroup_v1 = true;
+	}
+
+	if (opts->record_cgroup) {
+		skel->rodata->needs_cgroup = true;
+
+		if (!cgroup_is_v2("perf_event"))
+			skel->rodata->uses_cgroup_v1 = true;
+	}
+
+	set_max_rlimit();
+	check_sched_switch_args();
+
+	err = off_cpu_bpf__load(skel);
+	if (err) {
+		pr_err("Failed to load off-cpu skeleton\n");
+		goto out;
+	}
+
+	if (target->cpu_list) {
+		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->pid) {
+		u8 val = 1;
+
+		skel->bss->has_task = 1;
+		skel->bss->uses_tgid = 1;
+		fd = bpf_map__fd(skel->maps.task_filter);
+
+		strlist__for_each_entry(pos, pid_slist) {
+			char *end_ptr;
+			u32 tgid;
+			int pid = strtol(pos->s, &end_ptr, 10);
+
+			if (pid == INT_MIN || pid == INT_MAX ||
+			    (*end_ptr != '\0' && *end_ptr != ','))
+				continue;
+
+			tgid = pid;
+			bpf_map_update_elem(fd, &tgid, &val, BPF_ANY);
+		}
+	} else 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 (evlist__first(evlist)->cgrp) {
+		struct evsel *evsel;
+		u8 val = 1;
+
+		skel->bss->has_cgroup = 1;
+		fd = bpf_map__fd(skel->maps.cgroup_filter);
+
+		evlist__for_each_entry(evlist, evsel) {
+			struct cgroup *cgrp = evsel->cgrp;
+
+			if (cgrp == NULL)
+				continue;
+
+			if (!cgrp->id && read_cgroup_id(cgrp) < 0) {
+				pr_err("Failed to read cgroup id of %s\n",
+				       cgrp->name);
+				goto out;
+			}
+
+			bpf_map_update_elem(fd, &cgrp->id, &val, BPF_ANY);
+		}
+	}
+
+	err = off_cpu_bpf__attach(skel);
+	if (err) {
+		pr_err("Failed to attach off-cpu BPF skeleton\n");
+		goto out;
+	}
+
+	if (perf_hooks__set_hook("record_start", off_cpu_start, evlist) ||
+	    perf_hooks__set_hook("record_end", off_cpu_finish, evlist)) {
+		pr_err("Failed to attach off-cpu skeleton\n");
+		goto out;
+	}
+
+	return 0;
+
+out:
+	off_cpu_bpf__destroy(skel);
+	return -1;
+}
+
+int off_cpu_write(struct perf_session *session)
+{
+	int bytes = 0, size;
+	int fd, stack;
+	u64 sample_type, val, sid = 0;
+	struct evsel *evsel;
+	struct perf_data_file *file = &session->data->file;
+	struct off_cpu_key prev, key;
+	union off_cpu_data data = {
+		.hdr = {
+			.type = PERF_RECORD_SAMPLE,
+			.misc = PERF_RECORD_MISC_USER,
+		},
+	};
+	u64 tstamp = OFF_CPU_TIMESTAMP;
+
+	skel->bss->enabled = 0;
+
+	evsel = evlist__find_evsel_by_str(session->evlist, OFFCPU_EVENT);
+	if (evsel == NULL) {
+		pr_err("%s evsel not found\n", OFFCPU_EVENT);
+		return 0;
+	}
+
+	sample_type = evsel->core.attr.sample_type;
+
+	if (sample_type & ~OFFCPU_SAMPLE_TYPES) {
+		pr_err("not supported sample type: %llx\n",
+		       (unsigned long long)sample_type);
+		return -1;
+	}
+
+	if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER)) {
+		if (evsel->core.id)
+			sid = evsel->core.id[0];
+	}
+
+	fd = bpf_map__fd(skel->maps.off_cpu);
+	stack = bpf_map__fd(skel->maps.stacks);
+	memset(&prev, 0, sizeof(prev));
+
+	while (!bpf_map_get_next_key(fd, &prev, &key)) {
+		int n = 1;  /* start from perf_event_header */
+		int ip_pos = -1;
+
+		bpf_map_lookup_elem(fd, &key, &val);
+
+		if (sample_type & PERF_SAMPLE_IDENTIFIER)
+			data.array[n++] = sid;
+		if (sample_type & PERF_SAMPLE_IP) {
+			ip_pos = n;
+			data.array[n++] = 0;  /* will be updated */
+		}
+		if (sample_type & PERF_SAMPLE_TID)
+			data.array[n++] = (u64)key.pid << 32 | key.tgid;
+		if (sample_type & PERF_SAMPLE_TIME)
+			data.array[n++] = tstamp;
+		if (sample_type & PERF_SAMPLE_ID)
+			data.array[n++] = sid;
+		if (sample_type & PERF_SAMPLE_CPU)
+			data.array[n++] = 0;
+		if (sample_type & PERF_SAMPLE_PERIOD)
+			data.array[n++] = val;
+		if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+			int len = 0;
+
+			/* data.array[n] is callchain->nr (updated later) */
+			data.array[n + 1] = PERF_CONTEXT_USER;
+			data.array[n + 2] = 0;
+
+			bpf_map_lookup_elem(stack, &key.stack_id, &data.array[n + 2]);
+			while (data.array[n + 2 + len])
+				len++;
+
+			/* update length of callchain */
+			data.array[n] = len + 1;
+
+			/* update sample ip with the first callchain entry */
+			if (ip_pos >= 0)
+				data.array[ip_pos] = data.array[n + 2];
+
+			/* calculate sample callchain data array length */
+			n += len + 2;
+		}
+		if (sample_type & PERF_SAMPLE_CGROUP)
+			data.array[n++] = key.cgroup_id;
+
+		size = n * sizeof(u64);
+		data.hdr.size = size;
+		bytes += size;
+
+		if (perf_data_file__write(file, &data, size) < 0) {
+			pr_err("failed to write perf data, error: %m\n");
+			return bytes;
+		}
+
+		prev = key;
+		/* increase dummy timestamp to sort later samples */
+		tstamp++;
+	}
+	return bytes;
+}