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