// 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->rodata->has_task && skel->rodata->uses_tgid &&
perf_thread_map__pid(evlist->core.threads, 0) != -1) {
int fd;
u32 pid;
u8 val = 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)
{
struct btf *btf = btf__load_vmlinux_btf();
const struct btf_type *t1, *t2, *t3;
u32 type_id;
type_id = btf__find_by_name_kind(btf, "btf_trace_sched_switch",
BTF_KIND_TYPEDEF);
if ((s32)type_id < 0)
goto cleanup;
t1 = btf__type_by_id(btf, type_id);
if (t1 == NULL)
goto cleanup;
t2 = btf__type_by_id(btf, t1->type);
if (t2 == NULL || !btf_is_ptr(t2))
goto cleanup;
t3 = btf__type_by_id(btf, t2->type);
/* btf_trace func proto has one more argument for the context */
if (t3 && btf_is_func_proto(t3) && btf_vlen(t3) == 5) {
/* new format: pass prev_state as 4th arg */
skel->rodata->has_prev_state = true;
}
cleanup:
btf__free(btf);
}
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);
skel->rodata->has_cpu = 1;
}
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);
skel->rodata->has_task = 1;
skel->rodata->uses_tgid = 1;
} else if (target__has_task(target)) {
ntasks = perf_thread_map__nr(evlist->core.threads);
bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
skel->rodata->has_task = 1;
} else if (target__none(target)) {
bpf_map__set_max_entries(skel->maps.task_filter, MAX_PROC);
skel->rodata->has_task = 1;
skel->rodata->uses_tgid = 1;
}
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;
skel->rodata->has_cgroup = 1;
}
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;
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;
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;
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;
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;
}
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