// SPDX-License-Identifier: GPL-2.0
#include "util/cgroup.h"
#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.h"
#include "util/thread_map.h"
#include "util/lock-contention.h"
#include <linux/zalloc.h>
#include <linux/string.h>
#include <bpf/bpf.h>
#include <inttypes.h>
#include "bpf_skel/lock_contention.skel.h"
#include "bpf_skel/lock_data.h"
static struct lock_contention_bpf *skel;
int lock_contention_prepare(struct lock_contention *con)
{
int i, fd;
int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1, ncgrps = 1;
struct evlist *evlist = con->evlist;
struct target *target = con->target;
skel = lock_contention_bpf__open();
if (!skel) {
pr_err("Failed to open lock-contention BPF skeleton\n");
return -1;
}
bpf_map__set_value_size(skel->maps.stacks, con->max_stack * sizeof(u64));
bpf_map__set_max_entries(skel->maps.lock_stat, con->map_nr_entries);
bpf_map__set_max_entries(skel->maps.tstamp, con->map_nr_entries);
if (con->aggr_mode == LOCK_AGGR_TASK)
bpf_map__set_max_entries(skel->maps.task_data, con->map_nr_entries);
else
bpf_map__set_max_entries(skel->maps.task_data, 1);
if (con->save_callstack)
bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
else
bpf_map__set_max_entries(skel->maps.stacks, 1);
if (target__has_cpu(target)) {
skel->rodata->has_cpu = 1;
ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
}
if (target__has_task(target)) {
skel->rodata->has_task = 1;
ntasks = perf_thread_map__nr(evlist->core.threads);
}
if (con->filters->nr_types) {
skel->rodata->has_type = 1;
ntypes = con->filters->nr_types;
}
if (con->filters->nr_cgrps) {
skel->rodata->has_cgroup = 1;
ncgrps = con->filters->nr_cgrps;
}
/* resolve lock name filters to addr */
if (con->filters->nr_syms) {
struct symbol *sym;
struct map *kmap;
unsigned long *addrs;
for (i = 0; i < con->filters->nr_syms; i++) {
sym = machine__find_kernel_symbol_by_name(con->machine,
con->filters->syms[i],
&kmap);
if (sym == NULL) {
pr_warning("ignore unknown symbol: %s\n",
con->filters->syms[i]);
continue;
}
addrs = realloc(con->filters->addrs,
(con->filters->nr_addrs + 1) * sizeof(*addrs));
if (addrs == NULL) {
pr_warning("memory allocation failure\n");
continue;
}
addrs[con->filters->nr_addrs++] = map__unmap_ip(kmap, sym->start);
con->filters->addrs = addrs;
}
naddrs = con->filters->nr_addrs;
skel->rodata->has_addr = 1;
}
bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
bpf_map__set_max_entries(skel->maps.type_filter, ntypes);
bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);
bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps);
skel->rodata->stack_skip = con->stack_skip;
skel->rodata->aggr_mode = con->aggr_mode;
skel->rodata->needs_callstack = con->save_callstack;
skel->rodata->lock_owner = con->owner;
if (con->aggr_mode == LOCK_AGGR_CGROUP || con->filters->nr_cgrps) {
if (cgroup_is_v2("perf_event"))
skel->rodata->use_cgroup_v2 = 1;
}
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;
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;
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;
fd = bpf_map__fd(skel->maps.task_filter);
bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
}
if (con->filters->nr_types) {
u8 val = 1;
fd = bpf_map__fd(skel->maps.type_filter);
for (i = 0; i < con->filters->nr_types; i++)
bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);
}
if (con->filters->nr_addrs) {
u8 val = 1;
fd = bpf_map__fd(skel->maps.addr_filter);
for (i = 0; i < con->filters->nr_addrs; i++)
bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);
}
if (con->filters->nr_cgrps) {
u8 val = 1;
fd = bpf_map__fd(skel->maps.cgroup_filter);
for (i = 0; i < con->filters->nr_cgrps; i++)
bpf_map_update_elem(fd, &con->filters->cgrps[i], &val, BPF_ANY);
}
if (con->aggr_mode == LOCK_AGGR_CGROUP)
read_all_cgroups(&con->cgroups);
bpf_program__set_autoload(skel->progs.collect_lock_syms, false);
lock_contention_bpf__attach(skel);
return 0;
}
/*
* Run the BPF program directly using BPF_PROG_TEST_RUN to update the end
* timestamp in ktime so that it can calculate delta easily.
*/
static void mark_end_timestamp(void)
{
DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
.flags = BPF_F_TEST_RUN_ON_CPU,
);
int prog_fd = bpf_program__fd(skel->progs.end_timestamp);
bpf_prog_test_run_opts(prog_fd, &opts);
}
static void update_lock_stat(int map_fd, int pid, u64 end_ts,
enum lock_aggr_mode aggr_mode,
struct tstamp_data *ts_data)
{
u64 delta;
struct contention_key stat_key = {};
struct contention_data stat_data;
if (ts_data->timestamp >= end_ts)
return;
delta = end_ts - ts_data->timestamp;
switch (aggr_mode) {
case LOCK_AGGR_CALLER:
stat_key.stack_id = ts_data->stack_id;
break;
case LOCK_AGGR_TASK:
stat_key.pid = pid;
break;
case LOCK_AGGR_ADDR:
stat_key.lock_addr_or_cgroup = ts_data->lock;
break;
case LOCK_AGGR_CGROUP:
/* TODO */
return;
default:
return;
}
if (bpf_map_lookup_elem(map_fd, &stat_key, &stat_data) < 0)
return;
stat_data.total_time += delta;
stat_data.count++;
if (delta > stat_data.max_time)
stat_data.max_time = delta;
if (delta < stat_data.min_time)
stat_data.min_time = delta;
bpf_map_update_elem(map_fd, &stat_key, &stat_data, BPF_EXIST);
}
/*
* Account entries in the tstamp map (which didn't see the corresponding
* lock:contention_end tracepoint) using end_ts.
*/
static void account_end_timestamp(struct lock_contention *con)
{
int ts_fd, stat_fd;
int *prev_key, key;
u64 end_ts = skel->bss->end_ts;
int total_cpus;
enum lock_aggr_mode aggr_mode = con->aggr_mode;
struct tstamp_data ts_data, *cpu_data;
/* Iterate per-task tstamp map (key = TID) */
ts_fd = bpf_map__fd(skel->maps.tstamp);
stat_fd = bpf_map__fd(skel->maps.lock_stat);
prev_key = NULL;
while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {
if (bpf_map_lookup_elem(ts_fd, &key, &ts_data) == 0) {
int pid = key;
if (aggr_mode == LOCK_AGGR_TASK && con->owner)
pid = ts_data.flags;
update_lock_stat(stat_fd, pid, end_ts, aggr_mode,
&ts_data);
}
prev_key = &key;
}
/* Now it'll check per-cpu tstamp map which doesn't have TID. */
if (aggr_mode == LOCK_AGGR_TASK || aggr_mode == LOCK_AGGR_CGROUP)
return;
total_cpus = cpu__max_cpu().cpu;
ts_fd = bpf_map__fd(skel->maps.tstamp_cpu);
cpu_data = calloc(total_cpus, sizeof(*cpu_data));
if (cpu_data == NULL)
return;
prev_key = NULL;
while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {
if (bpf_map_lookup_elem(ts_fd, &key, cpu_data) < 0)
goto next;
for (int i = 0; i < total_cpus; i++) {
if (cpu_data[i].lock == 0)
continue;
update_lock_stat(stat_fd, -1, end_ts, aggr_mode,
&cpu_data[i]);
}
next:
prev_key = &key;
}
free(cpu_data);
}
int lock_contention_start(void)
{
skel->bss->enabled = 1;
return 0;
}
int lock_contention_stop(void)
{
skel->bss->enabled = 0;
mark_end_timestamp();
return 0;
}
static const char *lock_contention_get_name(struct lock_contention *con,
struct contention_key *key,
u64 *stack_trace, u32 flags)
{
int idx = 0;
u64 addr;
const char *name = "";
static char name_buf[KSYM_NAME_LEN];
struct symbol *sym;
struct map *kmap;
struct machine *machine = con->machine;
if (con->aggr_mode == LOCK_AGGR_TASK) {
struct contention_task_data task;
int pid = key->pid;
int task_fd = bpf_map__fd(skel->maps.task_data);
/* do not update idle comm which contains CPU number */
if (pid) {
struct thread *t = machine__findnew_thread(machine, /*pid=*/-1, pid);
if (t == NULL)
return name;
if (!bpf_map_lookup_elem(task_fd, &pid, &task) &&
thread__set_comm(t, task.comm, /*timestamp=*/0))
name = task.comm;
}
return name;
}
if (con->aggr_mode == LOCK_AGGR_ADDR) {
int lock_fd = bpf_map__fd(skel->maps.lock_syms);
/* per-process locks set upper bits of the flags */
if (flags & LCD_F_MMAP_LOCK)
return "mmap_lock";
if (flags & LCD_F_SIGHAND_LOCK)
return "siglock";
/* global locks with symbols */
sym = machine__find_kernel_symbol(machine, key->lock_addr_or_cgroup, &kmap);
if (sym)
return sym->name;
/* try semi-global locks collected separately */
if (!bpf_map_lookup_elem(lock_fd, &key->lock_addr_or_cgroup, &flags)) {
if (flags == LOCK_CLASS_RQLOCK)
return "rq_lock";
}
return "";
}
if (con->aggr_mode == LOCK_AGGR_CGROUP) {
u64 cgrp_id = key->lock_addr_or_cgroup;
struct cgroup *cgrp = __cgroup__find(&con->cgroups, cgrp_id);
if (cgrp)
return cgrp->name;
snprintf(name_buf, sizeof(name_buf), "cgroup:%" PRIu64 "", cgrp_id);
return name_buf;
}
/* LOCK_AGGR_CALLER: skip lock internal functions */
while (machine__is_lock_function(machine, stack_trace[idx]) &&
idx < con->max_stack - 1)
idx++;
addr = stack_trace[idx];
sym = machine__find_kernel_symbol(machine, addr, &kmap);
if (sym) {
unsigned long offset;
offset = map__map_ip(kmap, addr) - sym->start;
if (offset == 0)
return sym->name;
snprintf(name_buf, sizeof(name_buf), "%s+%#lx", sym->name, offset);
} else {
snprintf(name_buf, sizeof(name_buf), "%#lx", (unsigned long)addr);
}
return name_buf;
}
int lock_contention_read(struct lock_contention *con)
{
int fd, stack, err = 0;
struct contention_key *prev_key, key = {};
struct contention_data data = {};
struct lock_stat *st = NULL;
struct machine *machine = con->machine;
u64 *stack_trace;
size_t stack_size = con->max_stack * sizeof(*stack_trace);
fd = bpf_map__fd(skel->maps.lock_stat);
stack = bpf_map__fd(skel->maps.stacks);
con->fails.task = skel->bss->task_fail;
con->fails.stack = skel->bss->stack_fail;
con->fails.time = skel->bss->time_fail;
con->fails.data = skel->bss->data_fail;
stack_trace = zalloc(stack_size);
if (stack_trace == NULL)
return -1;
account_end_timestamp(con);
if (con->aggr_mode == LOCK_AGGR_TASK) {
struct thread *idle = machine__findnew_thread(machine,
/*pid=*/0,
/*tid=*/0);
thread__set_comm(idle, "swapper", /*timestamp=*/0);
}
if (con->aggr_mode == LOCK_AGGR_ADDR) {
DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
.flags = BPF_F_TEST_RUN_ON_CPU,
);
int prog_fd = bpf_program__fd(skel->progs.collect_lock_syms);
bpf_prog_test_run_opts(prog_fd, &opts);
}
/* make sure it loads the kernel map */
maps__load_first(machine->kmaps);
prev_key = NULL;
while (!bpf_map_get_next_key(fd, prev_key, &key)) {
s64 ls_key;
const char *name;
/* to handle errors in the loop body */
err = -1;
bpf_map_lookup_elem(fd, &key, &data);
if (con->save_callstack) {
bpf_map_lookup_elem(stack, &key.stack_id, stack_trace);
if (!match_callstack_filter(machine, stack_trace)) {
con->nr_filtered += data.count;
goto next;
}
}
switch (con->aggr_mode) {
case LOCK_AGGR_CALLER:
ls_key = key.stack_id;
break;
case LOCK_AGGR_TASK:
ls_key = key.pid;
break;
case LOCK_AGGR_ADDR:
case LOCK_AGGR_CGROUP:
ls_key = key.lock_addr_or_cgroup;
break;
default:
goto next;
}
st = lock_stat_find(ls_key);
if (st != NULL) {
st->wait_time_total += data.total_time;
if (st->wait_time_max < data.max_time)
st->wait_time_max = data.max_time;
if (st->wait_time_min > data.min_time)
st->wait_time_min = data.min_time;
st->nr_contended += data.count;
if (st->nr_contended)
st->avg_wait_time = st->wait_time_total / st->nr_contended;
goto next;
}
name = lock_contention_get_name(con, &key, stack_trace, data.flags);
st = lock_stat_findnew(ls_key, name, data.flags);
if (st == NULL)
break;
st->nr_contended = data.count;
st->wait_time_total = data.total_time;
st->wait_time_max = data.max_time;
st->wait_time_min = data.min_time;
if (data.count)
st->avg_wait_time = data.total_time / data.count;
if (con->aggr_mode == LOCK_AGGR_CALLER && verbose > 0) {
st->callstack = memdup(stack_trace, stack_size);
if (st->callstack == NULL)
break;
}
next:
prev_key = &key;
/* we're fine now, reset the error */
err = 0;
}
free(stack_trace);
return err;
}
int lock_contention_finish(struct lock_contention *con)
{
if (skel) {
skel->bss->enabled = 0;
lock_contention_bpf__destroy(skel);
}
while (!RB_EMPTY_ROOT(&con->cgroups)) {
struct rb_node *node = rb_first(&con->cgroups);
struct cgroup *cgrp = rb_entry(node, struct cgroup, node);
rb_erase(node, &con->cgroups);
cgroup__put(cgrp);
}
return 0;
}
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