1 // SPDX-License-Identifier: GPL-2.0-or-later <<
2 /* 1 /*
3 * Copyright (C) 2008-2014 Mathieu Desnoyers 2 * Copyright (C) 2008-2014 Mathieu Desnoyers
>> 3 *
>> 4 * This program is free software; you can redistribute it and/or modify
>> 5 * it under the terms of the GNU General Public License as published by
>> 6 * the Free Software Foundation; either version 2 of the License, or
>> 7 * (at your option) any later version.
>> 8 *
>> 9 * This program is distributed in the hope that it will be useful,
>> 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> 12 * GNU General Public License for more details.
>> 13 *
>> 14 * You should have received a copy of the GNU General Public License
>> 15 * along with this program; if not, write to the Free Software
>> 16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
4 */ 17 */
5 #include <linux/module.h> 18 #include <linux/module.h>
6 #include <linux/mutex.h> 19 #include <linux/mutex.h>
7 #include <linux/types.h> 20 #include <linux/types.h>
8 #include <linux/jhash.h> 21 #include <linux/jhash.h>
9 #include <linux/list.h> 22 #include <linux/list.h>
10 #include <linux/rcupdate.h> 23 #include <linux/rcupdate.h>
11 #include <linux/tracepoint.h> 24 #include <linux/tracepoint.h>
12 #include <linux/err.h> 25 #include <linux/err.h>
13 #include <linux/slab.h> 26 #include <linux/slab.h>
14 #include <linux/sched/signal.h> 27 #include <linux/sched/signal.h>
15 #include <linux/sched/task.h> 28 #include <linux/sched/task.h>
16 #include <linux/static_key.h> 29 #include <linux/static_key.h>
17 30
18 enum tp_func_state { <<
19 TP_FUNC_0, <<
20 TP_FUNC_1, <<
21 TP_FUNC_2, <<
22 TP_FUNC_N, <<
23 }; <<
24 <<
25 extern tracepoint_ptr_t __start___tracepoints_ 31 extern tracepoint_ptr_t __start___tracepoints_ptrs[];
26 extern tracepoint_ptr_t __stop___tracepoints_p 32 extern tracepoint_ptr_t __stop___tracepoints_ptrs[];
27 33
28 DEFINE_SRCU(tracepoint_srcu); 34 DEFINE_SRCU(tracepoint_srcu);
29 EXPORT_SYMBOL_GPL(tracepoint_srcu); 35 EXPORT_SYMBOL_GPL(tracepoint_srcu);
30 36
31 enum tp_transition_sync { <<
32 TP_TRANSITION_SYNC_1_0_1, <<
33 TP_TRANSITION_SYNC_N_2_1, <<
34 <<
35 _NR_TP_TRANSITION_SYNC, <<
36 }; <<
37 <<
38 struct tp_transition_snapshot { <<
39 unsigned long rcu; <<
40 unsigned long srcu; <<
41 bool ongoing; <<
42 }; <<
43 <<
44 /* Protected by tracepoints_mutex */ <<
45 static struct tp_transition_snapshot tp_transi <<
46 <<
47 static void tp_rcu_get_state(enum tp_transitio <<
48 { <<
49 struct tp_transition_snapshot *snapsho <<
50 <<
51 /* Keep the latest get_state snapshot. <<
52 snapshot->rcu = get_state_synchronize_ <<
53 snapshot->srcu = start_poll_synchroniz <<
54 snapshot->ongoing = true; <<
55 } <<
56 <<
57 static void tp_rcu_cond_sync(enum tp_transitio <<
58 { <<
59 struct tp_transition_snapshot *snapsho <<
60 <<
61 if (!snapshot->ongoing) <<
62 return; <<
63 cond_synchronize_rcu(snapshot->rcu); <<
64 if (!poll_state_synchronize_srcu(&trac <<
65 synchronize_srcu(&tracepoint_s <<
66 snapshot->ongoing = false; <<
67 } <<
68 <<
69 /* Set to 1 to enable tracepoint debug output 37 /* Set to 1 to enable tracepoint debug output */
70 static const int tracepoint_debug; 38 static const int tracepoint_debug;
71 39
72 #ifdef CONFIG_MODULES 40 #ifdef CONFIG_MODULES
73 /* 41 /*
74 * Tracepoint module list mutex protects the l 42 * Tracepoint module list mutex protects the local module list.
75 */ 43 */
76 static DEFINE_MUTEX(tracepoint_module_list_mut 44 static DEFINE_MUTEX(tracepoint_module_list_mutex);
77 45
78 /* Local list of struct tp_module */ 46 /* Local list of struct tp_module */
79 static LIST_HEAD(tracepoint_module_list); 47 static LIST_HEAD(tracepoint_module_list);
80 #endif /* CONFIG_MODULES */ 48 #endif /* CONFIG_MODULES */
81 49
82 /* 50 /*
83 * tracepoints_mutex protects the builtin and 51 * tracepoints_mutex protects the builtin and module tracepoints.
84 * tracepoints_mutex nests inside tracepoint_m 52 * tracepoints_mutex nests inside tracepoint_module_list_mutex.
85 */ 53 */
86 static DEFINE_MUTEX(tracepoints_mutex); 54 static DEFINE_MUTEX(tracepoints_mutex);
87 55
88 static struct rcu_head *early_probes; 56 static struct rcu_head *early_probes;
89 static bool ok_to_free_tracepoints; 57 static bool ok_to_free_tracepoints;
90 58
91 /* 59 /*
92 * Note about RCU : 60 * Note about RCU :
93 * It is used to delay the free of multiple pr 61 * It is used to delay the free of multiple probes array until a quiescent
94 * state is reached. 62 * state is reached.
95 */ 63 */
96 struct tp_probes { 64 struct tp_probes {
97 struct rcu_head rcu; 65 struct rcu_head rcu;
98 struct tracepoint_func probes[]; !! 66 struct tracepoint_func probes[0];
99 }; 67 };
100 68
101 /* Called in removal of a func but failed to a 69 /* Called in removal of a func but failed to allocate a new tp_funcs */
102 static void tp_stub_func(void) 70 static void tp_stub_func(void)
103 { 71 {
104 return; 72 return;
105 } 73 }
106 74
107 static inline void *allocate_probes(int count) 75 static inline void *allocate_probes(int count)
108 { 76 {
109 struct tp_probes *p = kmalloc(struct_ !! 77 struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func)
110 GFP_KER !! 78 + sizeof(struct tp_probes), GFP_KERNEL);
111 return p == NULL ? NULL : p->probes; 79 return p == NULL ? NULL : p->probes;
112 } 80 }
113 81
114 static void srcu_free_old_probes(struct rcu_he 82 static void srcu_free_old_probes(struct rcu_head *head)
115 { 83 {
116 kfree(container_of(head, struct tp_pro 84 kfree(container_of(head, struct tp_probes, rcu));
117 } 85 }
118 86
119 static void rcu_free_old_probes(struct rcu_hea 87 static void rcu_free_old_probes(struct rcu_head *head)
120 { 88 {
121 call_srcu(&tracepoint_srcu, head, srcu 89 call_srcu(&tracepoint_srcu, head, srcu_free_old_probes);
122 } 90 }
123 91
124 static __init int release_early_probes(void) 92 static __init int release_early_probes(void)
125 { 93 {
126 struct rcu_head *tmp; 94 struct rcu_head *tmp;
127 95
128 ok_to_free_tracepoints = true; 96 ok_to_free_tracepoints = true;
129 97
130 while (early_probes) { 98 while (early_probes) {
131 tmp = early_probes; 99 tmp = early_probes;
132 early_probes = tmp->next; 100 early_probes = tmp->next;
133 call_rcu(tmp, rcu_free_old_pro !! 101 call_rcu_sched(tmp, rcu_free_old_probes);
134 } 102 }
135 103
136 return 0; 104 return 0;
137 } 105 }
138 106
139 /* SRCU is initialized at core_initcall */ 107 /* SRCU is initialized at core_initcall */
140 postcore_initcall(release_early_probes); 108 postcore_initcall(release_early_probes);
141 109
142 static inline void release_probes(struct trace 110 static inline void release_probes(struct tracepoint_func *old)
143 { 111 {
144 if (old) { 112 if (old) {
145 struct tp_probes *tp_probes = 113 struct tp_probes *tp_probes = container_of(old,
146 struct tp_probes, prob 114 struct tp_probes, probes[0]);
147 115
148 /* 116 /*
149 * We can't free probes if SRC 117 * We can't free probes if SRCU is not initialized yet.
150 * Postpone the freeing till a 118 * Postpone the freeing till after SRCU is initialized.
151 */ 119 */
152 if (unlikely(!ok_to_free_trace 120 if (unlikely(!ok_to_free_tracepoints)) {
153 tp_probes->rcu.next = 121 tp_probes->rcu.next = early_probes;
154 early_probes = &tp_pro 122 early_probes = &tp_probes->rcu;
155 return; 123 return;
156 } 124 }
157 125
158 /* 126 /*
159 * Tracepoint probes are prote 127 * Tracepoint probes are protected by both sched RCU and SRCU,
160 * by calling the SRCU callbac 128 * by calling the SRCU callback in the sched RCU callback we
161 * cover both cases. So let us 129 * cover both cases. So let us chain the SRCU and sched RCU
162 * callbacks to wait for both 130 * callbacks to wait for both grace periods.
163 */ 131 */
164 call_rcu(&tp_probes->rcu, rcu_ !! 132 call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes);
165 } 133 }
166 } 134 }
167 135
168 static void debug_print_probes(struct tracepoi 136 static void debug_print_probes(struct tracepoint_func *funcs)
169 { 137 {
170 int i; 138 int i;
171 139
172 if (!tracepoint_debug || !funcs) 140 if (!tracepoint_debug || !funcs)
173 return; 141 return;
174 142
175 for (i = 0; funcs[i].func; i++) 143 for (i = 0; funcs[i].func; i++)
176 printk(KERN_DEBUG "Probe %d : 144 printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func);
177 } 145 }
178 146
179 static struct tracepoint_func * 147 static struct tracepoint_func *
180 func_add(struct tracepoint_func **funcs, struc 148 func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
181 int prio) 149 int prio)
182 { 150 {
183 struct tracepoint_func *old, *new; 151 struct tracepoint_func *old, *new;
184 int iter_probes; /* Iterate ove !! 152 int nr_probes = 0;
185 int nr_probes = 0; /* Counter for !! 153 int stub_funcs = 0;
186 int pos = -1; /* Insertion p !! 154 int pos = -1;
187 155
188 if (WARN_ON(!tp_func->func)) 156 if (WARN_ON(!tp_func->func))
189 return ERR_PTR(-EINVAL); 157 return ERR_PTR(-EINVAL);
190 158
191 debug_print_probes(*funcs); 159 debug_print_probes(*funcs);
192 old = *funcs; 160 old = *funcs;
193 if (old) { 161 if (old) {
194 /* (N -> N+1), (N != 0, 1) pro 162 /* (N -> N+1), (N != 0, 1) probes */
195 for (iter_probes = 0; old[iter !! 163 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
196 if (old[iter_probes].f !! 164 /* Insert before probes of lower priority */
197 continue; !! 165 if (pos < 0 && old[nr_probes].prio < prio)
198 if (old[iter_probes].f !! 166 pos = nr_probes;
199 old[iter_probes].d !! 167 if (old[nr_probes].func == tp_func->func &&
>> 168 old[nr_probes].data == tp_func->data)
200 return ERR_PTR 169 return ERR_PTR(-EEXIST);
201 nr_probes++; !! 170 if (old[nr_probes].func == tp_stub_func)
>> 171 stub_funcs++;
202 } 172 }
203 } 173 }
204 /* + 2 : one for new probe, one for NU !! 174 /* + 2 : one for new probe, one for NULL func - stub functions */
205 new = allocate_probes(nr_probes + 2); !! 175 new = allocate_probes(nr_probes + 2 - stub_funcs);
206 if (new == NULL) 176 if (new == NULL)
207 return ERR_PTR(-ENOMEM); 177 return ERR_PTR(-ENOMEM);
208 if (old) { 178 if (old) {
209 nr_probes = 0; !! 179 if (stub_funcs) {
210 for (iter_probes = 0; old[iter !! 180 /* Need to copy one at a time to remove stubs */
211 if (old[iter_probes].f !! 181 int probes = 0;
212 continue; !! 182
213 /* Insert before probe !! 183 pos = -1;
214 if (pos < 0 && old[ite !! 184 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
215 pos = nr_probe !! 185 if (old[nr_probes].func == tp_stub_func)
216 new[nr_probes++] = old !! 186 continue;
>> 187 if (pos < 0 && old[nr_probes].prio < prio)
>> 188 pos = probes++;
>> 189 new[probes++] = old[nr_probes];
>> 190 }
>> 191 nr_probes = probes;
>> 192 if (pos < 0)
>> 193 pos = probes;
>> 194 else
>> 195 nr_probes--; /* Account for insertion */
>> 196
>> 197 } else if (pos < 0) {
>> 198 pos = nr_probes;
>> 199 memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
>> 200 } else {
>> 201 /* Copy higher priority probes ahead of the new probe */
>> 202 memcpy(new, old, pos * sizeof(struct tracepoint_func));
>> 203 /* Copy the rest after it. */
>> 204 memcpy(new + pos + 1, old + pos,
>> 205 (nr_probes - pos) * sizeof(struct tracepoint_func));
217 } 206 }
218 if (pos < 0) !! 207 } else
219 pos = nr_probes++; <<
220 /* nr_probes now points to the <<
221 } else { <<
222 pos = 0; 208 pos = 0;
223 nr_probes = 1; /* must point a <<
224 } <<
225 new[pos] = *tp_func; 209 new[pos] = *tp_func;
226 new[nr_probes].func = NULL; !! 210 new[nr_probes + 1].func = NULL;
227 *funcs = new; 211 *funcs = new;
228 debug_print_probes(*funcs); 212 debug_print_probes(*funcs);
229 return old; 213 return old;
230 } 214 }
231 215
232 static void *func_remove(struct tracepoint_fun 216 static void *func_remove(struct tracepoint_func **funcs,
233 struct tracepoint_func *tp_fun 217 struct tracepoint_func *tp_func)
234 { 218 {
235 int nr_probes = 0, nr_del = 0, i; 219 int nr_probes = 0, nr_del = 0, i;
236 struct tracepoint_func *old, *new; 220 struct tracepoint_func *old, *new;
237 221
238 old = *funcs; 222 old = *funcs;
239 223
240 if (!old) 224 if (!old)
241 return ERR_PTR(-ENOENT); 225 return ERR_PTR(-ENOENT);
242 226
243 debug_print_probes(*funcs); 227 debug_print_probes(*funcs);
244 /* (N -> M), (N > 1, M >= 0) probes */ 228 /* (N -> M), (N > 1, M >= 0) probes */
245 if (tp_func->func) { 229 if (tp_func->func) {
246 for (nr_probes = 0; old[nr_pro 230 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
247 if ((old[nr_probes].fu 231 if ((old[nr_probes].func == tp_func->func &&
248 old[nr_probes].da 232 old[nr_probes].data == tp_func->data) ||
249 old[nr_probes].fun 233 old[nr_probes].func == tp_stub_func)
250 nr_del++; 234 nr_del++;
251 } 235 }
252 } 236 }
253 237
254 /* 238 /*
255 * If probe is NULL, then nr_probes = 239 * If probe is NULL, then nr_probes = nr_del = 0, and then the
256 * entire entry will be removed. 240 * entire entry will be removed.
257 */ 241 */
258 if (nr_probes - nr_del == 0) { 242 if (nr_probes - nr_del == 0) {
259 /* N -> 0, (N > 1) */ 243 /* N -> 0, (N > 1) */
260 *funcs = NULL; 244 *funcs = NULL;
261 debug_print_probes(*funcs); 245 debug_print_probes(*funcs);
262 return old; 246 return old;
263 } else { 247 } else {
264 int j = 0; 248 int j = 0;
265 /* N -> M, (N > 1, M > 0) */ 249 /* N -> M, (N > 1, M > 0) */
266 /* + 1 for NULL */ 250 /* + 1 for NULL */
267 new = allocate_probes(nr_probe 251 new = allocate_probes(nr_probes - nr_del + 1);
268 if (new) { 252 if (new) {
269 for (i = 0; old[i].fun !! 253 for (i = 0; old[i].func; i++)
270 if ((old[i].fu !! 254 if ((old[i].func != tp_func->func
271 old[i].da !! 255 || old[i].data != tp_func->data)
272 old[i].fun !! 256 && old[i].func != tp_stub_func)
273 new[j+ 257 new[j++] = old[i];
274 } <<
275 new[nr_probes - nr_del 258 new[nr_probes - nr_del].func = NULL;
276 *funcs = new; 259 *funcs = new;
277 } else { 260 } else {
278 /* 261 /*
279 * Failed to allocate, 262 * Failed to allocate, replace the old function
280 * with calls to tp_st 263 * with calls to tp_stub_func.
281 */ 264 */
282 for (i = 0; old[i].fun !! 265 for (i = 0; old[i].func; i++)
283 if (old[i].fun 266 if (old[i].func == tp_func->func &&
284 old[i].dat !! 267 old[i].data == tp_func->data) {
285 WRITE_ !! 268 old[i].func = tp_stub_func;
286 } !! 269 /* Set the prio to the next event. */
>> 270 if (old[i + 1].func)
>> 271 old[i].prio =
>> 272 old[i + 1].prio;
>> 273 else
>> 274 old[i].prio = -1;
>> 275 }
287 *funcs = old; 276 *funcs = old;
288 } 277 }
289 } 278 }
290 debug_print_probes(*funcs); 279 debug_print_probes(*funcs);
291 return old; 280 return old;
292 } 281 }
293 282
294 /* 283 /*
295 * Count the number of functions (enum tp_func <<
296 */ <<
297 static enum tp_func_state nr_func_state(const <<
298 { <<
299 if (!tp_funcs) <<
300 return TP_FUNC_0; <<
301 if (!tp_funcs[1].func) <<
302 return TP_FUNC_1; <<
303 if (!tp_funcs[2].func) <<
304 return TP_FUNC_2; <<
305 return TP_FUNC_N; /* 3 or more * <<
306 } <<
307 <<
308 static void tracepoint_update_call(struct trac <<
309 { <<
310 void *func = tp->iterator; <<
311 <<
312 /* Synthetic events do not have static <<
313 if (!tp->static_call_key) <<
314 return; <<
315 if (nr_func_state(tp_funcs) == TP_FUNC <<
316 func = tp_funcs[0].func; <<
317 __static_call_update(tp->static_call_k <<
318 } <<
319 <<
320 /* <<
321 * Add the probe function to a tracepoint. 284 * Add the probe function to a tracepoint.
322 */ 285 */
323 static int tracepoint_add_func(struct tracepoi 286 static int tracepoint_add_func(struct tracepoint *tp,
324 struct tracepoi 287 struct tracepoint_func *func, int prio,
325 bool warn) 288 bool warn)
326 { 289 {
327 struct tracepoint_func *old, *tp_funcs 290 struct tracepoint_func *old, *tp_funcs;
328 int ret; 291 int ret;
329 292
330 if (tp->regfunc && !static_key_enabled 293 if (tp->regfunc && !static_key_enabled(&tp->key)) {
331 ret = tp->regfunc(); 294 ret = tp->regfunc();
332 if (ret < 0) 295 if (ret < 0)
333 return ret; 296 return ret;
334 } 297 }
335 298
336 tp_funcs = rcu_dereference_protected(t 299 tp_funcs = rcu_dereference_protected(tp->funcs,
337 lockdep_is_held(&trace 300 lockdep_is_held(&tracepoints_mutex));
338 old = func_add(&tp_funcs, func, prio); 301 old = func_add(&tp_funcs, func, prio);
339 if (IS_ERR(old)) { 302 if (IS_ERR(old)) {
340 WARN_ON_ONCE(warn && PTR_ERR(o 303 WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM);
341 return PTR_ERR(old); 304 return PTR_ERR(old);
342 } 305 }
343 306
344 /* 307 /*
345 * rcu_assign_pointer has as smp_store 308 * rcu_assign_pointer has as smp_store_release() which makes sure
346 * that the new probe callbacks array 309 * that the new probe callbacks array is consistent before setting
347 * a pointer to it. This array is ref 310 * a pointer to it. This array is referenced by __DO_TRACE from
348 * include/linux/tracepoint.h using rc 311 * include/linux/tracepoint.h using rcu_dereference_sched().
349 */ 312 */
350 switch (nr_func_state(tp_funcs)) { !! 313 rcu_assign_pointer(tp->funcs, tp_funcs);
351 case TP_FUNC_1: /* 0->1 */ !! 314 if (!static_key_enabled(&tp->key))
352 /* !! 315 static_key_slow_inc(&tp->key);
353 * Make sure new static func n <<
354 * 1->0->1 transition sequence <<
355 */ <<
356 tp_rcu_cond_sync(TP_TRANSITION <<
357 /* Set static call to first fu <<
358 tracepoint_update_call(tp, tp_ <<
359 /* Both iterator and static ca <<
360 rcu_assign_pointer(tp->funcs, <<
361 static_key_enable(&tp->key); <<
362 break; <<
363 case TP_FUNC_2: /* 1->2 */ <<
364 /* Set iterator static call */ <<
365 tracepoint_update_call(tp, tp_ <<
366 /* <<
367 * Iterator callback installed <<
368 * Requires ordering between R <<
369 * static call update/call. <<
370 */ <<
371 fallthrough; <<
372 case TP_FUNC_N: /* N->N+1 (N>1 <<
373 rcu_assign_pointer(tp->funcs, <<
374 /* <<
375 * Make sure static func never <<
376 * N->...->2->1 (N>1) transiti <<
377 */ <<
378 if (tp_funcs[0].data != old[0] <<
379 tp_rcu_get_state(TP_TR <<
380 break; <<
381 default: <<
382 WARN_ON_ONCE(1); <<
383 break; <<
384 } <<
385 <<
386 release_probes(old); 316 release_probes(old);
387 return 0; 317 return 0;
388 } 318 }
389 319
390 /* 320 /*
391 * Remove a probe function from a tracepoint. 321 * Remove a probe function from a tracepoint.
392 * Note: only waiting an RCU period after sett 322 * Note: only waiting an RCU period after setting elem->call to the empty
393 * function insures that the original callback 323 * function insures that the original callback is not used anymore. This insured
394 * by preempt_disable around the call site. 324 * by preempt_disable around the call site.
395 */ 325 */
396 static int tracepoint_remove_func(struct trace 326 static int tracepoint_remove_func(struct tracepoint *tp,
397 struct tracepoint_func *func) 327 struct tracepoint_func *func)
398 { 328 {
399 struct tracepoint_func *old, *tp_funcs 329 struct tracepoint_func *old, *tp_funcs;
400 330
401 tp_funcs = rcu_dereference_protected(t 331 tp_funcs = rcu_dereference_protected(tp->funcs,
402 lockdep_is_held(&trace 332 lockdep_is_held(&tracepoints_mutex));
403 old = func_remove(&tp_funcs, func); 333 old = func_remove(&tp_funcs, func);
404 if (WARN_ON_ONCE(IS_ERR(old))) 334 if (WARN_ON_ONCE(IS_ERR(old)))
405 return PTR_ERR(old); 335 return PTR_ERR(old);
406 336
407 if (tp_funcs == old) 337 if (tp_funcs == old)
408 /* Failed allocating new tp_fu 338 /* Failed allocating new tp_funcs, replaced func with stub */
409 return 0; 339 return 0;
410 340
411 switch (nr_func_state(tp_funcs)) { !! 341 if (!tp_funcs) {
412 case TP_FUNC_0: /* 1->0 */ <<
413 /* Removed last function */ 342 /* Removed last function */
414 if (tp->unregfunc && static_ke 343 if (tp->unregfunc && static_key_enabled(&tp->key))
415 tp->unregfunc(); 344 tp->unregfunc();
416 345
417 static_key_disable(&tp->key); !! 346 if (static_key_enabled(&tp->key))
418 /* Set iterator static call */ !! 347 static_key_slow_dec(&tp->key);
419 tracepoint_update_call(tp, tp_ <<
420 /* Both iterator and static ca <<
421 rcu_assign_pointer(tp->funcs, <<
422 /* <<
423 * Make sure new static func n <<
424 * 1->0->1 transition sequence <<
425 */ <<
426 tp_rcu_get_state(TP_TRANSITION <<
427 break; <<
428 case TP_FUNC_1: /* 2->1 */ <<
429 rcu_assign_pointer(tp->funcs, <<
430 /* <<
431 * Make sure static func never <<
432 * N->...->2->1 (N>2) transiti <<
433 * element's data has changed, <<
434 * to prevent current readers <<
435 * from calling the new functi <<
436 */ <<
437 if (tp_funcs[0].data != old[0] <<
438 tp_rcu_get_state(TP_TR <<
439 tp_rcu_cond_sync(TP_TRANSITION <<
440 /* Set static call to first fu <<
441 tracepoint_update_call(tp, tp_ <<
442 break; <<
443 case TP_FUNC_2: /* N->N-1 (N>2 <<
444 fallthrough; <<
445 case TP_FUNC_N: <<
446 rcu_assign_pointer(tp->funcs, <<
447 /* <<
448 * Make sure static func never <<
449 * N->...->2->1 (N>2) transiti <<
450 */ <<
451 if (tp_funcs[0].data != old[0] <<
452 tp_rcu_get_state(TP_TR <<
453 break; <<
454 default: <<
455 WARN_ON_ONCE(1); <<
456 break; <<
457 } 348 }
>> 349 rcu_assign_pointer(tp->funcs, tp_funcs);
458 release_probes(old); 350 release_probes(old);
459 return 0; 351 return 0;
460 } 352 }
461 353
462 /** 354 /**
463 * tracepoint_probe_register_prio_may_exist - 355 * tracepoint_probe_register_prio_may_exist - Connect a probe to a tracepoint with priority
464 * @tp: tracepoint 356 * @tp: tracepoint
465 * @probe: probe handler 357 * @probe: probe handler
466 * @data: tracepoint data 358 * @data: tracepoint data
467 * @prio: priority of this function over other 359 * @prio: priority of this function over other registered functions
468 * 360 *
469 * Same as tracepoint_probe_register_prio() ex 361 * Same as tracepoint_probe_register_prio() except that it will not warn
470 * if the tracepoint is already registered. 362 * if the tracepoint is already registered.
471 */ 363 */
472 int tracepoint_probe_register_prio_may_exist(s 364 int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe,
473 v 365 void *data, int prio)
474 { 366 {
475 struct tracepoint_func tp_func; 367 struct tracepoint_func tp_func;
476 int ret; 368 int ret;
477 369
478 mutex_lock(&tracepoints_mutex); 370 mutex_lock(&tracepoints_mutex);
479 tp_func.func = probe; 371 tp_func.func = probe;
480 tp_func.data = data; 372 tp_func.data = data;
481 tp_func.prio = prio; 373 tp_func.prio = prio;
482 ret = tracepoint_add_func(tp, &tp_func 374 ret = tracepoint_add_func(tp, &tp_func, prio, false);
483 mutex_unlock(&tracepoints_mutex); 375 mutex_unlock(&tracepoints_mutex);
484 return ret; 376 return ret;
485 } 377 }
486 EXPORT_SYMBOL_GPL(tracepoint_probe_register_pr 378 EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist);
487 379
488 /** 380 /**
489 * tracepoint_probe_register_prio - Connect a 381 * tracepoint_probe_register_prio - Connect a probe to a tracepoint with priority
490 * @tp: tracepoint 382 * @tp: tracepoint
491 * @probe: probe handler 383 * @probe: probe handler
492 * @data: tracepoint data 384 * @data: tracepoint data
493 * @prio: priority of this function over other 385 * @prio: priority of this function over other registered functions
494 * 386 *
495 * Returns 0 if ok, error value on error. 387 * Returns 0 if ok, error value on error.
496 * Note: if @tp is within a module, the caller 388 * Note: if @tp is within a module, the caller is responsible for
497 * unregistering the probe before the module i 389 * unregistering the probe before the module is gone. This can be
498 * performed either with a tracepoint module g 390 * performed either with a tracepoint module going notifier, or from
499 * within module exit functions. 391 * within module exit functions.
500 */ 392 */
501 int tracepoint_probe_register_prio(struct trac 393 int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe,
502 void *data, 394 void *data, int prio)
503 { 395 {
504 struct tracepoint_func tp_func; 396 struct tracepoint_func tp_func;
505 int ret; 397 int ret;
506 398
507 mutex_lock(&tracepoints_mutex); 399 mutex_lock(&tracepoints_mutex);
508 tp_func.func = probe; 400 tp_func.func = probe;
509 tp_func.data = data; 401 tp_func.data = data;
510 tp_func.prio = prio; 402 tp_func.prio = prio;
511 ret = tracepoint_add_func(tp, &tp_func 403 ret = tracepoint_add_func(tp, &tp_func, prio, true);
512 mutex_unlock(&tracepoints_mutex); 404 mutex_unlock(&tracepoints_mutex);
513 return ret; 405 return ret;
514 } 406 }
515 EXPORT_SYMBOL_GPL(tracepoint_probe_register_pr 407 EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio);
516 408
517 /** 409 /**
518 * tracepoint_probe_register - Connect a prob 410 * tracepoint_probe_register - Connect a probe to a tracepoint
519 * @tp: tracepoint 411 * @tp: tracepoint
520 * @probe: probe handler 412 * @probe: probe handler
521 * @data: tracepoint data 413 * @data: tracepoint data
522 * 414 *
523 * Returns 0 if ok, error value on error. 415 * Returns 0 if ok, error value on error.
524 * Note: if @tp is within a module, the caller 416 * Note: if @tp is within a module, the caller is responsible for
525 * unregistering the probe before the module i 417 * unregistering the probe before the module is gone. This can be
526 * performed either with a tracepoint module g 418 * performed either with a tracepoint module going notifier, or from
527 * within module exit functions. 419 * within module exit functions.
528 */ 420 */
529 int tracepoint_probe_register(struct tracepoin 421 int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
530 { 422 {
531 return tracepoint_probe_register_prio( 423 return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO);
532 } 424 }
533 EXPORT_SYMBOL_GPL(tracepoint_probe_register); 425 EXPORT_SYMBOL_GPL(tracepoint_probe_register);
534 426
535 /** 427 /**
536 * tracepoint_probe_unregister - Disconnect a 428 * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
537 * @tp: tracepoint 429 * @tp: tracepoint
538 * @probe: probe function pointer 430 * @probe: probe function pointer
539 * @data: tracepoint data 431 * @data: tracepoint data
540 * 432 *
541 * Returns 0 if ok, error value on error. 433 * Returns 0 if ok, error value on error.
542 */ 434 */
543 int tracepoint_probe_unregister(struct tracepo 435 int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
544 { 436 {
545 struct tracepoint_func tp_func; 437 struct tracepoint_func tp_func;
546 int ret; 438 int ret;
547 439
548 mutex_lock(&tracepoints_mutex); 440 mutex_lock(&tracepoints_mutex);
549 tp_func.func = probe; 441 tp_func.func = probe;
550 tp_func.data = data; 442 tp_func.data = data;
551 ret = tracepoint_remove_func(tp, &tp_f 443 ret = tracepoint_remove_func(tp, &tp_func);
552 mutex_unlock(&tracepoints_mutex); 444 mutex_unlock(&tracepoints_mutex);
553 return ret; 445 return ret;
554 } 446 }
555 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister) 447 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
556 448
557 static void for_each_tracepoint_range( 449 static void for_each_tracepoint_range(
558 tracepoint_ptr_t *begin, trace 450 tracepoint_ptr_t *begin, tracepoint_ptr_t *end,
559 void (*fct)(struct tracepoint 451 void (*fct)(struct tracepoint *tp, void *priv),
560 void *priv) 452 void *priv)
561 { 453 {
562 tracepoint_ptr_t *iter; 454 tracepoint_ptr_t *iter;
563 455
564 if (!begin) 456 if (!begin)
565 return; 457 return;
566 for (iter = begin; iter < end; iter++) 458 for (iter = begin; iter < end; iter++)
567 fct(tracepoint_ptr_deref(iter) 459 fct(tracepoint_ptr_deref(iter), priv);
568 } 460 }
569 461
570 #ifdef CONFIG_MODULES 462 #ifdef CONFIG_MODULES
571 bool trace_module_has_bad_taint(struct module 463 bool trace_module_has_bad_taint(struct module *mod)
572 { 464 {
573 return mod->taints & ~((1 << TAINT_OOT 465 return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
574 (1 << TAINT_UN !! 466 (1 << TAINT_UNSIGNED_MODULE));
575 (1 << TAINT_LI <<
576 } 467 }
577 468
578 static BLOCKING_NOTIFIER_HEAD(tracepoint_notif 469 static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
579 470
580 /** 471 /**
581 * register_tracepoint_module_notifier - regis !! 472 * register_tracepoint_notifier - register tracepoint coming/going notifier
582 * @nb: notifier block 473 * @nb: notifier block
583 * 474 *
584 * Notifiers registered with this function are 475 * Notifiers registered with this function are called on module
585 * coming/going with the tracepoint_module_lis 476 * coming/going with the tracepoint_module_list_mutex held.
586 * The notifier block callback should expect a 477 * The notifier block callback should expect a "struct tp_module" data
587 * pointer. 478 * pointer.
588 */ 479 */
589 int register_tracepoint_module_notifier(struct 480 int register_tracepoint_module_notifier(struct notifier_block *nb)
590 { 481 {
591 struct tp_module *tp_mod; 482 struct tp_module *tp_mod;
592 int ret; 483 int ret;
593 484
594 mutex_lock(&tracepoint_module_list_mut 485 mutex_lock(&tracepoint_module_list_mutex);
595 ret = blocking_notifier_chain_register 486 ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb);
596 if (ret) 487 if (ret)
597 goto end; 488 goto end;
598 list_for_each_entry(tp_mod, &tracepoin 489 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
599 (void) nb->notifier_call(nb, M 490 (void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod);
600 end: 491 end:
601 mutex_unlock(&tracepoint_module_list_m 492 mutex_unlock(&tracepoint_module_list_mutex);
602 return ret; 493 return ret;
603 } 494 }
604 EXPORT_SYMBOL_GPL(register_tracepoint_module_n 495 EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier);
605 496
606 /** 497 /**
607 * unregister_tracepoint_module_notifier - unr !! 498 * unregister_tracepoint_notifier - unregister tracepoint coming/going notifier
608 * @nb: notifier block 499 * @nb: notifier block
609 * 500 *
610 * The notifier block callback should expect a 501 * The notifier block callback should expect a "struct tp_module" data
611 * pointer. 502 * pointer.
612 */ 503 */
613 int unregister_tracepoint_module_notifier(stru 504 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
614 { 505 {
615 struct tp_module *tp_mod; 506 struct tp_module *tp_mod;
616 int ret; 507 int ret;
617 508
618 mutex_lock(&tracepoint_module_list_mut 509 mutex_lock(&tracepoint_module_list_mutex);
619 ret = blocking_notifier_chain_unregist 510 ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb);
620 if (ret) 511 if (ret)
621 goto end; 512 goto end;
622 list_for_each_entry(tp_mod, &tracepoin 513 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
623 (void) nb->notifier_call(nb, M 514 (void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod);
624 end: 515 end:
625 mutex_unlock(&tracepoint_module_list_m 516 mutex_unlock(&tracepoint_module_list_mutex);
626 return ret; 517 return ret;
627 518
628 } 519 }
629 EXPORT_SYMBOL_GPL(unregister_tracepoint_module 520 EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
630 521
631 /* 522 /*
632 * Ensure the tracer unregistered the module's 523 * Ensure the tracer unregistered the module's probes before the module
633 * teardown is performed. Prevents leaks of pr 524 * teardown is performed. Prevents leaks of probe and data pointers.
634 */ 525 */
635 static void tp_module_going_check_quiescent(st 526 static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv)
636 { 527 {
637 WARN_ON_ONCE(tp->funcs); 528 WARN_ON_ONCE(tp->funcs);
638 } 529 }
639 530
640 static int tracepoint_module_coming(struct mod 531 static int tracepoint_module_coming(struct module *mod)
641 { 532 {
642 struct tp_module *tp_mod; 533 struct tp_module *tp_mod;
>> 534 int ret = 0;
643 535
644 if (!mod->num_tracepoints) 536 if (!mod->num_tracepoints)
645 return 0; 537 return 0;
646 538
647 /* 539 /*
648 * We skip modules that taint the kern 540 * We skip modules that taint the kernel, especially those with different
649 * module headers (for forced load), t 541 * module headers (for forced load), to make sure we don't cause a crash.
650 * Staging, out-of-tree, unsigned GPL, !! 542 * Staging, out-of-tree, and unsigned GPL modules are fine.
651 */ 543 */
652 if (trace_module_has_bad_taint(mod)) 544 if (trace_module_has_bad_taint(mod))
653 return 0; 545 return 0;
654 !! 546 mutex_lock(&tracepoint_module_list_mutex);
655 tp_mod = kmalloc(sizeof(struct tp_modu 547 tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
656 if (!tp_mod) !! 548 if (!tp_mod) {
657 return -ENOMEM; !! 549 ret = -ENOMEM;
>> 550 goto end;
>> 551 }
658 tp_mod->mod = mod; 552 tp_mod->mod = mod;
659 <<
660 mutex_lock(&tracepoint_module_list_mut <<
661 list_add_tail(&tp_mod->list, &tracepoi 553 list_add_tail(&tp_mod->list, &tracepoint_module_list);
662 blocking_notifier_call_chain(&tracepoi 554 blocking_notifier_call_chain(&tracepoint_notify_list,
663 MODULE_STATE_COMING, t 555 MODULE_STATE_COMING, tp_mod);
>> 556 end:
664 mutex_unlock(&tracepoint_module_list_m 557 mutex_unlock(&tracepoint_module_list_mutex);
665 return 0; !! 558 return ret;
666 } 559 }
667 560
668 static void tracepoint_module_going(struct mod 561 static void tracepoint_module_going(struct module *mod)
669 { 562 {
670 struct tp_module *tp_mod; 563 struct tp_module *tp_mod;
671 564
672 if (!mod->num_tracepoints) 565 if (!mod->num_tracepoints)
673 return; 566 return;
674 567
675 mutex_lock(&tracepoint_module_list_mut 568 mutex_lock(&tracepoint_module_list_mutex);
676 list_for_each_entry(tp_mod, &tracepoin 569 list_for_each_entry(tp_mod, &tracepoint_module_list, list) {
677 if (tp_mod->mod == mod) { 570 if (tp_mod->mod == mod) {
678 blocking_notifier_call 571 blocking_notifier_call_chain(&tracepoint_notify_list,
679 MODULE 572 MODULE_STATE_GOING, tp_mod);
680 list_del(&tp_mod->list 573 list_del(&tp_mod->list);
681 kfree(tp_mod); 574 kfree(tp_mod);
682 /* 575 /*
683 * Called the going no 576 * Called the going notifier before checking for
684 * quiescence. 577 * quiescence.
685 */ 578 */
686 for_each_tracepoint_ra 579 for_each_tracepoint_range(mod->tracepoints_ptrs,
687 mod->tracepoin 580 mod->tracepoints_ptrs + mod->num_tracepoints,
688 tp_module_goin 581 tp_module_going_check_quiescent, NULL);
689 break; 582 break;
690 } 583 }
691 } 584 }
692 /* 585 /*
693 * In the case of modules that were ta 586 * In the case of modules that were tainted at "coming", we'll simply
694 * walk through the list without findi 587 * walk through the list without finding it. We cannot use the "tainted"
695 * flag on "going", in case a module t 588 * flag on "going", in case a module taints the kernel only after being
696 * loaded. 589 * loaded.
697 */ 590 */
698 mutex_unlock(&tracepoint_module_list_m 591 mutex_unlock(&tracepoint_module_list_mutex);
699 } 592 }
700 593
701 static int tracepoint_module_notify(struct not 594 static int tracepoint_module_notify(struct notifier_block *self,
702 unsigned long val, void *data) 595 unsigned long val, void *data)
703 { 596 {
704 struct module *mod = data; 597 struct module *mod = data;
705 int ret = 0; 598 int ret = 0;
706 599
707 switch (val) { 600 switch (val) {
708 case MODULE_STATE_COMING: 601 case MODULE_STATE_COMING:
709 ret = tracepoint_module_coming 602 ret = tracepoint_module_coming(mod);
710 break; 603 break;
711 case MODULE_STATE_LIVE: 604 case MODULE_STATE_LIVE:
712 break; 605 break;
713 case MODULE_STATE_GOING: 606 case MODULE_STATE_GOING:
714 tracepoint_module_going(mod); 607 tracepoint_module_going(mod);
715 break; 608 break;
716 case MODULE_STATE_UNFORMED: 609 case MODULE_STATE_UNFORMED:
717 break; 610 break;
718 } 611 }
719 return notifier_from_errno(ret); !! 612 return ret;
720 } 613 }
721 614
722 static struct notifier_block tracepoint_module 615 static struct notifier_block tracepoint_module_nb = {
723 .notifier_call = tracepoint_module_not 616 .notifier_call = tracepoint_module_notify,
724 .priority = 0, 617 .priority = 0,
725 }; 618 };
726 619
727 static __init int init_tracepoints(void) 620 static __init int init_tracepoints(void)
728 { 621 {
729 int ret; 622 int ret;
730 623
731 ret = register_module_notifier(&tracep 624 ret = register_module_notifier(&tracepoint_module_nb);
732 if (ret) 625 if (ret)
733 pr_warn("Failed to register tr 626 pr_warn("Failed to register tracepoint module enter notifier\n");
734 627
735 return ret; 628 return ret;
736 } 629 }
737 __initcall(init_tracepoints); 630 __initcall(init_tracepoints);
738 #endif /* CONFIG_MODULES */ 631 #endif /* CONFIG_MODULES */
739 632
740 /** 633 /**
741 * for_each_kernel_tracepoint - iteration on a 634 * for_each_kernel_tracepoint - iteration on all kernel tracepoints
742 * @fct: callback 635 * @fct: callback
743 * @priv: private data 636 * @priv: private data
744 */ 637 */
745 void for_each_kernel_tracepoint(void (*fct)(st 638 void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
746 void *priv) 639 void *priv)
747 { 640 {
748 for_each_tracepoint_range(__start___tr 641 for_each_tracepoint_range(__start___tracepoints_ptrs,
749 __stop___tracepoints_ptrs, fct 642 __stop___tracepoints_ptrs, fct, priv);
750 } 643 }
751 EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint); 644 EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);
752 645
753 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS 646 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
754 647
755 /* NB: reg/unreg are called while guarded with 648 /* NB: reg/unreg are called while guarded with the tracepoints_mutex */
756 static int sys_tracepoint_refcount; 649 static int sys_tracepoint_refcount;
757 650
758 int syscall_regfunc(void) 651 int syscall_regfunc(void)
759 { 652 {
760 struct task_struct *p, *t; 653 struct task_struct *p, *t;
761 654
762 if (!sys_tracepoint_refcount) { 655 if (!sys_tracepoint_refcount) {
763 read_lock(&tasklist_lock); 656 read_lock(&tasklist_lock);
764 for_each_process_thread(p, t) 657 for_each_process_thread(p, t) {
765 set_task_syscall_work( !! 658 set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
766 } 659 }
767 read_unlock(&tasklist_lock); 660 read_unlock(&tasklist_lock);
768 } 661 }
769 sys_tracepoint_refcount++; 662 sys_tracepoint_refcount++;
770 663
771 return 0; 664 return 0;
772 } 665 }
773 666
774 void syscall_unregfunc(void) 667 void syscall_unregfunc(void)
775 { 668 {
776 struct task_struct *p, *t; 669 struct task_struct *p, *t;
777 670
778 sys_tracepoint_refcount--; 671 sys_tracepoint_refcount--;
779 if (!sys_tracepoint_refcount) { 672 if (!sys_tracepoint_refcount) {
780 read_lock(&tasklist_lock); 673 read_lock(&tasklist_lock);
781 for_each_process_thread(p, t) 674 for_each_process_thread(p, t) {
782 clear_task_syscall_wor !! 675 clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
783 } 676 }
784 read_unlock(&tasklist_lock); 677 read_unlock(&tasklist_lock);
785 } 678 }
786 } 679 }
787 #endif 680 #endif
788 681
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