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