1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Infrastructure for statistic tracing (histogram output). |
4 | * |
5 | * Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com> |
6 | * |
7 | * Based on the code from trace_branch.c which is |
8 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> |
9 | * |
10 | */ |
11 | |
12 | #include <linux/security.h> |
13 | #include <linux/list.h> |
14 | #include <linux/slab.h> |
15 | #include <linux/rbtree.h> |
16 | #include <linux/tracefs.h> |
17 | #include "trace_stat.h" |
18 | #include "trace.h" |
19 | |
20 | |
21 | /* |
22 | * List of stat red-black nodes from a tracer |
23 | * We use a such tree to sort quickly the stat |
24 | * entries from the tracer. |
25 | */ |
26 | struct stat_node { |
27 | struct rb_node node; |
28 | void *stat; |
29 | }; |
30 | |
31 | /* A stat session is the stats output in one file */ |
32 | struct stat_session { |
33 | struct list_head session_list; |
34 | struct tracer_stat *ts; |
35 | struct rb_root stat_root; |
36 | struct mutex stat_mutex; |
37 | struct dentry *file; |
38 | }; |
39 | |
40 | /* All of the sessions currently in use. Each stat file embed one session */ |
41 | static LIST_HEAD(all_stat_sessions); |
42 | static DEFINE_MUTEX(all_stat_sessions_mutex); |
43 | |
44 | /* The root directory for all stat files */ |
45 | static struct dentry *stat_dir; |
46 | |
47 | static void __reset_stat_session(struct stat_session *session) |
48 | { |
49 | struct stat_node *snode, *n; |
50 | |
51 | rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) { |
52 | if (session->ts->stat_release) |
53 | session->ts->stat_release(snode->stat); |
54 | kfree(objp: snode); |
55 | } |
56 | |
57 | session->stat_root = RB_ROOT; |
58 | } |
59 | |
60 | static void reset_stat_session(struct stat_session *session) |
61 | { |
62 | mutex_lock(&session->stat_mutex); |
63 | __reset_stat_session(session); |
64 | mutex_unlock(lock: &session->stat_mutex); |
65 | } |
66 | |
67 | static void destroy_session(struct stat_session *session) |
68 | { |
69 | tracefs_remove(dentry: session->file); |
70 | __reset_stat_session(session); |
71 | mutex_destroy(lock: &session->stat_mutex); |
72 | kfree(objp: session); |
73 | } |
74 | |
75 | static int insert_stat(struct rb_root *root, void *stat, cmp_func_t cmp) |
76 | { |
77 | struct rb_node **new = &(root->rb_node), *parent = NULL; |
78 | struct stat_node *data; |
79 | |
80 | data = kzalloc(size: sizeof(*data), GFP_KERNEL); |
81 | if (!data) |
82 | return -ENOMEM; |
83 | data->stat = stat; |
84 | |
85 | /* |
86 | * Figure out where to put new node |
87 | * This is a descendent sorting |
88 | */ |
89 | while (*new) { |
90 | struct stat_node *this; |
91 | int result; |
92 | |
93 | this = container_of(*new, struct stat_node, node); |
94 | result = cmp(data->stat, this->stat); |
95 | |
96 | parent = *new; |
97 | if (result >= 0) |
98 | new = &((*new)->rb_left); |
99 | else |
100 | new = &((*new)->rb_right); |
101 | } |
102 | |
103 | rb_link_node(node: &data->node, parent, rb_link: new); |
104 | rb_insert_color(&data->node, root); |
105 | return 0; |
106 | } |
107 | |
108 | /* |
109 | * For tracers that don't provide a stat_cmp callback. |
110 | * This one will force an insertion as right-most node |
111 | * in the rbtree. |
112 | */ |
113 | static int dummy_cmp(const void *p1, const void *p2) |
114 | { |
115 | return -1; |
116 | } |
117 | |
118 | /* |
119 | * Initialize the stat rbtree at each trace_stat file opening. |
120 | * All of these copies and sorting are required on all opening |
121 | * since the stats could have changed between two file sessions. |
122 | */ |
123 | static int stat_seq_init(struct stat_session *session) |
124 | { |
125 | struct tracer_stat *ts = session->ts; |
126 | struct rb_root *root = &session->stat_root; |
127 | void *stat; |
128 | int ret = 0; |
129 | int i; |
130 | |
131 | mutex_lock(&session->stat_mutex); |
132 | __reset_stat_session(session); |
133 | |
134 | if (!ts->stat_cmp) |
135 | ts->stat_cmp = dummy_cmp; |
136 | |
137 | stat = ts->stat_start(ts); |
138 | if (!stat) |
139 | goto exit; |
140 | |
141 | ret = insert_stat(root, stat, cmp: ts->stat_cmp); |
142 | if (ret) |
143 | goto exit; |
144 | |
145 | /* |
146 | * Iterate over the tracer stat entries and store them in an rbtree. |
147 | */ |
148 | for (i = 1; ; i++) { |
149 | stat = ts->stat_next(stat, i); |
150 | |
151 | /* End of insertion */ |
152 | if (!stat) |
153 | break; |
154 | |
155 | ret = insert_stat(root, stat, cmp: ts->stat_cmp); |
156 | if (ret) |
157 | goto exit_free_rbtree; |
158 | } |
159 | |
160 | exit: |
161 | mutex_unlock(lock: &session->stat_mutex); |
162 | return ret; |
163 | |
164 | exit_free_rbtree: |
165 | __reset_stat_session(session); |
166 | mutex_unlock(lock: &session->stat_mutex); |
167 | return ret; |
168 | } |
169 | |
170 | |
171 | static void *stat_seq_start(struct seq_file *s, loff_t *pos) |
172 | { |
173 | struct stat_session *session = s->private; |
174 | struct rb_node *node; |
175 | int n = *pos; |
176 | int i; |
177 | |
178 | /* Prevent from tracer switch or rbtree modification */ |
179 | mutex_lock(&session->stat_mutex); |
180 | |
181 | /* If we are in the beginning of the file, print the headers */ |
182 | if (session->ts->stat_headers) { |
183 | if (n == 0) |
184 | return SEQ_START_TOKEN; |
185 | n--; |
186 | } |
187 | |
188 | node = rb_first(&session->stat_root); |
189 | for (i = 0; node && i < n; i++) |
190 | node = rb_next(node); |
191 | |
192 | return node; |
193 | } |
194 | |
195 | static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos) |
196 | { |
197 | struct stat_session *session = s->private; |
198 | struct rb_node *node = p; |
199 | |
200 | (*pos)++; |
201 | |
202 | if (p == SEQ_START_TOKEN) |
203 | return rb_first(&session->stat_root); |
204 | |
205 | return rb_next(node); |
206 | } |
207 | |
208 | static void stat_seq_stop(struct seq_file *s, void *p) |
209 | { |
210 | struct stat_session *session = s->private; |
211 | mutex_unlock(lock: &session->stat_mutex); |
212 | } |
213 | |
214 | static int stat_seq_show(struct seq_file *s, void *v) |
215 | { |
216 | struct stat_session *session = s->private; |
217 | struct stat_node *l = container_of(v, struct stat_node, node); |
218 | |
219 | if (v == SEQ_START_TOKEN) |
220 | return session->ts->stat_headers(s); |
221 | |
222 | return session->ts->stat_show(s, l->stat); |
223 | } |
224 | |
225 | static const struct seq_operations trace_stat_seq_ops = { |
226 | .start = stat_seq_start, |
227 | .next = stat_seq_next, |
228 | .stop = stat_seq_stop, |
229 | .show = stat_seq_show |
230 | }; |
231 | |
232 | /* The session stat is refilled and resorted at each stat file opening */ |
233 | static int tracing_stat_open(struct inode *inode, struct file *file) |
234 | { |
235 | int ret; |
236 | struct seq_file *m; |
237 | struct stat_session *session = inode->i_private; |
238 | |
239 | ret = security_locked_down(what: LOCKDOWN_TRACEFS); |
240 | if (ret) |
241 | return ret; |
242 | |
243 | ret = stat_seq_init(session); |
244 | if (ret) |
245 | return ret; |
246 | |
247 | ret = seq_open(file, &trace_stat_seq_ops); |
248 | if (ret) { |
249 | reset_stat_session(session); |
250 | return ret; |
251 | } |
252 | |
253 | m = file->private_data; |
254 | m->private = session; |
255 | return ret; |
256 | } |
257 | |
258 | /* |
259 | * Avoid consuming memory with our now useless rbtree. |
260 | */ |
261 | static int tracing_stat_release(struct inode *i, struct file *f) |
262 | { |
263 | struct stat_session *session = i->i_private; |
264 | |
265 | reset_stat_session(session); |
266 | |
267 | return seq_release(i, f); |
268 | } |
269 | |
270 | static const struct file_operations tracing_stat_fops = { |
271 | .open = tracing_stat_open, |
272 | .read = seq_read, |
273 | .llseek = seq_lseek, |
274 | .release = tracing_stat_release |
275 | }; |
276 | |
277 | static int tracing_stat_init(void) |
278 | { |
279 | int ret; |
280 | |
281 | ret = tracing_init_dentry(); |
282 | if (ret) |
283 | return -ENODEV; |
284 | |
285 | stat_dir = tracefs_create_dir(name: "trace_stat" , NULL); |
286 | if (!stat_dir) { |
287 | pr_warn("Could not create tracefs 'trace_stat' entry\n" ); |
288 | return -ENOMEM; |
289 | } |
290 | return 0; |
291 | } |
292 | |
293 | static int init_stat_file(struct stat_session *session) |
294 | { |
295 | int ret; |
296 | |
297 | if (!stat_dir && (ret = tracing_stat_init())) |
298 | return ret; |
299 | |
300 | session->file = tracefs_create_file(name: session->ts->name, TRACE_MODE_WRITE, |
301 | parent: stat_dir, data: session, |
302 | fops: &tracing_stat_fops); |
303 | if (!session->file) |
304 | return -ENOMEM; |
305 | return 0; |
306 | } |
307 | |
308 | int register_stat_tracer(struct tracer_stat *trace) |
309 | { |
310 | struct stat_session *session, *node; |
311 | int ret = -EINVAL; |
312 | |
313 | if (!trace) |
314 | return -EINVAL; |
315 | |
316 | if (!trace->stat_start || !trace->stat_next || !trace->stat_show) |
317 | return -EINVAL; |
318 | |
319 | /* Already registered? */ |
320 | mutex_lock(&all_stat_sessions_mutex); |
321 | list_for_each_entry(node, &all_stat_sessions, session_list) { |
322 | if (node->ts == trace) |
323 | goto out; |
324 | } |
325 | |
326 | ret = -ENOMEM; |
327 | /* Init the session */ |
328 | session = kzalloc(size: sizeof(*session), GFP_KERNEL); |
329 | if (!session) |
330 | goto out; |
331 | |
332 | session->ts = trace; |
333 | INIT_LIST_HEAD(list: &session->session_list); |
334 | mutex_init(&session->stat_mutex); |
335 | |
336 | ret = init_stat_file(session); |
337 | if (ret) { |
338 | destroy_session(session); |
339 | goto out; |
340 | } |
341 | |
342 | ret = 0; |
343 | /* Register */ |
344 | list_add_tail(new: &session->session_list, head: &all_stat_sessions); |
345 | out: |
346 | mutex_unlock(lock: &all_stat_sessions_mutex); |
347 | |
348 | return ret; |
349 | } |
350 | |
351 | void unregister_stat_tracer(struct tracer_stat *trace) |
352 | { |
353 | struct stat_session *node, *tmp; |
354 | |
355 | mutex_lock(&all_stat_sessions_mutex); |
356 | list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) { |
357 | if (node->ts == trace) { |
358 | list_del(entry: &node->session_list); |
359 | destroy_session(session: node); |
360 | break; |
361 | } |
362 | } |
363 | mutex_unlock(lock: &all_stat_sessions_mutex); |
364 | } |
365 | |