1 // SPDX-License-Identifier: GPL-2.0
2 #include "util/debug.h"
3 #include "util/evlist.h"
4 #include "util/machine.h"
5 #include "util/map.h"
6 #include "util/symbol.h"
7 #include "util/target.h"
8 #include "util/thread_map.h"
9 #include "util/lock-contention.h"
10 #include <linux/zalloc.h>
11 #include <bpf/bpf.h>
12 
13 #include "bpf_skel/lock_contention.skel.h"
14 
15 static struct lock_contention_bpf *skel;
16 
17 /* should be same as bpf_skel/lock_contention.bpf.c */
18 struct lock_contention_key {
19 	s32 stack_id;
20 };
21 
22 struct lock_contention_data {
23 	u64 total_time;
24 	u64 min_time;
25 	u64 max_time;
26 	u32 count;
27 	u32 flags;
28 };
29 
30 int lock_contention_prepare(struct lock_contention *con)
31 {
32 	int i, fd;
33 	int ncpus = 1, ntasks = 1;
34 	struct evlist *evlist = con->evlist;
35 	struct target *target = con->target;
36 
37 	skel = lock_contention_bpf__open();
38 	if (!skel) {
39 		pr_err("Failed to open lock-contention BPF skeleton\n");
40 		return -1;
41 	}
42 
43 	bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
44 	bpf_map__set_max_entries(skel->maps.lock_stat, con->map_nr_entries);
45 
46 	if (target__has_cpu(target))
47 		ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
48 	if (target__has_task(target))
49 		ntasks = perf_thread_map__nr(evlist->core.threads);
50 
51 	bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
52 	bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
53 
54 	if (lock_contention_bpf__load(skel) < 0) {
55 		pr_err("Failed to load lock-contention BPF skeleton\n");
56 		return -1;
57 	}
58 
59 	if (target__has_cpu(target)) {
60 		u32 cpu;
61 		u8 val = 1;
62 
63 		skel->bss->has_cpu = 1;
64 		fd = bpf_map__fd(skel->maps.cpu_filter);
65 
66 		for (i = 0; i < ncpus; i++) {
67 			cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;
68 			bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
69 		}
70 	}
71 
72 	if (target__has_task(target)) {
73 		u32 pid;
74 		u8 val = 1;
75 
76 		skel->bss->has_task = 1;
77 		fd = bpf_map__fd(skel->maps.task_filter);
78 
79 		for (i = 0; i < ntasks; i++) {
80 			pid = perf_thread_map__pid(evlist->core.threads, i);
81 			bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
82 		}
83 	}
84 
85 	if (target__none(target) && evlist->workload.pid > 0) {
86 		u32 pid = evlist->workload.pid;
87 		u8 val = 1;
88 
89 		skel->bss->has_task = 1;
90 		fd = bpf_map__fd(skel->maps.task_filter);
91 		bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
92 	}
93 
94 	lock_contention_bpf__attach(skel);
95 	return 0;
96 }
97 
98 int lock_contention_start(void)
99 {
100 	skel->bss->enabled = 1;
101 	return 0;
102 }
103 
104 int lock_contention_stop(void)
105 {
106 	skel->bss->enabled = 0;
107 	return 0;
108 }
109 
110 int lock_contention_read(struct lock_contention *con)
111 {
112 	int fd, stack;
113 	s32 prev_key, key;
114 	struct lock_contention_data data;
115 	struct lock_stat *st;
116 	struct machine *machine = con->machine;
117 	u64 stack_trace[CONTENTION_STACK_DEPTH];
118 
119 	fd = bpf_map__fd(skel->maps.lock_stat);
120 	stack = bpf_map__fd(skel->maps.stacks);
121 
122 	con->lost = skel->bss->lost;
123 
124 	prev_key = 0;
125 	while (!bpf_map_get_next_key(fd, &prev_key, &key)) {
126 		struct map *kmap;
127 		struct symbol *sym;
128 		int idx;
129 
130 		bpf_map_lookup_elem(fd, &key, &data);
131 		st = zalloc(sizeof(*st));
132 		if (st == NULL)
133 			return -1;
134 
135 		st->nr_contended = data.count;
136 		st->wait_time_total = data.total_time;
137 		st->wait_time_max = data.max_time;
138 		st->wait_time_min = data.min_time;
139 
140 		if (data.count)
141 			st->avg_wait_time = data.total_time / data.count;
142 
143 		st->flags = data.flags;
144 
145 		bpf_map_lookup_elem(stack, &key, stack_trace);
146 
147 		/* skip BPF + lock internal functions */
148 		idx = CONTENTION_STACK_SKIP;
149 		while (is_lock_function(machine, stack_trace[idx]) &&
150 		       idx < CONTENTION_STACK_DEPTH - 1)
151 			idx++;
152 
153 		st->addr = stack_trace[idx];
154 		sym = machine__find_kernel_symbol(machine, st->addr, &kmap);
155 
156 		if (sym) {
157 			unsigned long offset;
158 			int ret = 0;
159 
160 			offset = kmap->map_ip(kmap, st->addr) - sym->start;
161 
162 			if (offset)
163 				ret = asprintf(&st->name, "%s+%#lx", sym->name, offset);
164 			else
165 				st->name = strdup(sym->name);
166 
167 			if (ret < 0 || st->name == NULL)
168 				return -1;
169 		} else if (asprintf(&st->name, "%#lx", (unsigned long)st->addr) < 0) {
170 			free(st);
171 			return -1;
172 		}
173 
174 		hlist_add_head(&st->hash_entry, con->result);
175 		prev_key = key;
176 	}
177 
178 	return 0;
179 }
180 
181 int lock_contention_finish(void)
182 {
183 	if (skel) {
184 		skel->bss->enabled = 0;
185 		lock_contention_bpf__destroy(skel);
186 	}
187 
188 	return 0;
189 }
190