1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Infrastructure to took into function calls and returns. |
4 | * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com> |
5 | * Mostly borrowed from function tracer which |
6 | * is Copyright (c) Steven Rostedt <srostedt@redhat.com> |
7 | * |
8 | * Highly modified by Steven Rostedt (VMware). |
9 | */ |
10 | #include <linux/jump_label.h> |
11 | #include <linux/suspend.h> |
12 | #include <linux/ftrace.h> |
13 | #include <linux/slab.h> |
14 | |
15 | #include <trace/events/sched.h> |
16 | |
17 | #include "ftrace_internal.h" |
18 | #include "trace.h" |
19 | |
20 | #ifdef CONFIG_DYNAMIC_FTRACE |
21 | #define ASSIGN_OPS_HASH(opsname, val) \ |
22 | .func_hash = val, \ |
23 | .local_hash.regex_lock = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock), |
24 | #else |
25 | #define ASSIGN_OPS_HASH(opsname, val) |
26 | #endif |
27 | |
28 | DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph); |
29 | int ftrace_graph_active; |
30 | |
31 | /* Both enabled by default (can be cleared by function_graph tracer flags */ |
32 | static bool fgraph_sleep_time = true; |
33 | |
34 | #ifdef CONFIG_DYNAMIC_FTRACE |
35 | /* |
36 | * archs can override this function if they must do something |
37 | * to enable hook for graph tracer. |
38 | */ |
39 | int __weak ftrace_enable_ftrace_graph_caller(void) |
40 | { |
41 | return 0; |
42 | } |
43 | |
44 | /* |
45 | * archs can override this function if they must do something |
46 | * to disable hook for graph tracer. |
47 | */ |
48 | int __weak ftrace_disable_ftrace_graph_caller(void) |
49 | { |
50 | return 0; |
51 | } |
52 | #endif |
53 | |
54 | /** |
55 | * ftrace_graph_stop - set to permanently disable function graph tracing |
56 | * |
57 | * In case of an error int function graph tracing, this is called |
58 | * to try to keep function graph tracing from causing any more harm. |
59 | * Usually this is pretty severe and this is called to try to at least |
60 | * get a warning out to the user. |
61 | */ |
62 | void ftrace_graph_stop(void) |
63 | { |
64 | static_branch_enable(&kill_ftrace_graph); |
65 | } |
66 | |
67 | /* Add a function return address to the trace stack on thread info.*/ |
68 | static int |
69 | ftrace_push_return_trace(unsigned long ret, unsigned long func, |
70 | unsigned long frame_pointer, unsigned long *retp) |
71 | { |
72 | unsigned long long calltime; |
73 | int index; |
74 | |
75 | if (unlikely(ftrace_graph_is_dead())) |
76 | return -EBUSY; |
77 | |
78 | if (!current->ret_stack) |
79 | return -EBUSY; |
80 | |
81 | /* |
82 | * We must make sure the ret_stack is tested before we read |
83 | * anything else. |
84 | */ |
85 | smp_rmb(); |
86 | |
87 | /* The return trace stack is full */ |
88 | if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) { |
89 | atomic_inc(v: ¤t->trace_overrun); |
90 | return -EBUSY; |
91 | } |
92 | |
93 | calltime = trace_clock_local(); |
94 | |
95 | index = ++current->curr_ret_stack; |
96 | barrier(); |
97 | current->ret_stack[index].ret = ret; |
98 | current->ret_stack[index].func = func; |
99 | current->ret_stack[index].calltime = calltime; |
100 | #ifdef HAVE_FUNCTION_GRAPH_FP_TEST |
101 | current->ret_stack[index].fp = frame_pointer; |
102 | #endif |
103 | #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR |
104 | current->ret_stack[index].retp = retp; |
105 | #endif |
106 | return 0; |
107 | } |
108 | |
109 | /* |
110 | * Not all archs define MCOUNT_INSN_SIZE which is used to look for direct |
111 | * functions. But those archs currently don't support direct functions |
112 | * anyway, and ftrace_find_rec_direct() is just a stub for them. |
113 | * Define MCOUNT_INSN_SIZE to keep those archs compiling. |
114 | */ |
115 | #ifndef MCOUNT_INSN_SIZE |
116 | /* Make sure this only works without direct calls */ |
117 | # ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS |
118 | # error MCOUNT_INSN_SIZE not defined with direct calls enabled |
119 | # endif |
120 | # define MCOUNT_INSN_SIZE 0 |
121 | #endif |
122 | |
123 | int function_graph_enter(unsigned long ret, unsigned long func, |
124 | unsigned long frame_pointer, unsigned long *retp) |
125 | { |
126 | struct ftrace_graph_ent trace; |
127 | |
128 | #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS |
129 | /* |
130 | * Skip graph tracing if the return location is served by direct trampoline, |
131 | * since call sequence and return addresses are unpredictable anyway. |
132 | * Ex: BPF trampoline may call original function and may skip frame |
133 | * depending on type of BPF programs attached. |
134 | */ |
135 | if (ftrace_direct_func_count && |
136 | ftrace_find_rec_direct(ret - MCOUNT_INSN_SIZE)) |
137 | return -EBUSY; |
138 | #endif |
139 | trace.func = func; |
140 | trace.depth = ++current->curr_ret_depth; |
141 | |
142 | if (ftrace_push_return_trace(ret, func, frame_pointer, retp)) |
143 | goto out; |
144 | |
145 | /* Only trace if the calling function expects to */ |
146 | if (!ftrace_graph_entry(&trace)) |
147 | goto out_ret; |
148 | |
149 | return 0; |
150 | out_ret: |
151 | current->curr_ret_stack--; |
152 | out: |
153 | current->curr_ret_depth--; |
154 | return -EBUSY; |
155 | } |
156 | |
157 | /* Retrieve a function return address to the trace stack on thread info.*/ |
158 | static void |
159 | ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, |
160 | unsigned long frame_pointer) |
161 | { |
162 | int index; |
163 | |
164 | index = current->curr_ret_stack; |
165 | |
166 | if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) { |
167 | ftrace_graph_stop(); |
168 | WARN_ON(1); |
169 | /* Might as well panic, otherwise we have no where to go */ |
170 | *ret = (unsigned long)panic; |
171 | return; |
172 | } |
173 | |
174 | #ifdef HAVE_FUNCTION_GRAPH_FP_TEST |
175 | /* |
176 | * The arch may choose to record the frame pointer used |
177 | * and check it here to make sure that it is what we expect it |
178 | * to be. If gcc does not set the place holder of the return |
179 | * address in the frame pointer, and does a copy instead, then |
180 | * the function graph trace will fail. This test detects this |
181 | * case. |
182 | * |
183 | * Currently, x86_32 with optimize for size (-Os) makes the latest |
184 | * gcc do the above. |
185 | * |
186 | * Note, -mfentry does not use frame pointers, and this test |
187 | * is not needed if CC_USING_FENTRY is set. |
188 | */ |
189 | if (unlikely(current->ret_stack[index].fp != frame_pointer)) { |
190 | ftrace_graph_stop(); |
191 | WARN(1, "Bad frame pointer: expected %lx, received %lx\n" |
192 | " from func %ps return to %lx\n" , |
193 | current->ret_stack[index].fp, |
194 | frame_pointer, |
195 | (void *)current->ret_stack[index].func, |
196 | current->ret_stack[index].ret); |
197 | *ret = (unsigned long)panic; |
198 | return; |
199 | } |
200 | #endif |
201 | |
202 | *ret = current->ret_stack[index].ret; |
203 | trace->func = current->ret_stack[index].func; |
204 | trace->calltime = current->ret_stack[index].calltime; |
205 | trace->overrun = atomic_read(v: ¤t->trace_overrun); |
206 | trace->depth = current->curr_ret_depth--; |
207 | /* |
208 | * We still want to trace interrupts coming in if |
209 | * max_depth is set to 1. Make sure the decrement is |
210 | * seen before ftrace_graph_return. |
211 | */ |
212 | barrier(); |
213 | } |
214 | |
215 | /* |
216 | * Hibernation protection. |
217 | * The state of the current task is too much unstable during |
218 | * suspend/restore to disk. We want to protect against that. |
219 | */ |
220 | static int |
221 | ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state, |
222 | void *unused) |
223 | { |
224 | switch (state) { |
225 | case PM_HIBERNATION_PREPARE: |
226 | pause_graph_tracing(); |
227 | break; |
228 | |
229 | case PM_POST_HIBERNATION: |
230 | unpause_graph_tracing(); |
231 | break; |
232 | } |
233 | return NOTIFY_DONE; |
234 | } |
235 | |
236 | static struct notifier_block ftrace_suspend_notifier = { |
237 | .notifier_call = ftrace_suspend_notifier_call, |
238 | }; |
239 | |
240 | /* fgraph_ret_regs is not defined without CONFIG_FUNCTION_GRAPH_RETVAL */ |
241 | struct fgraph_ret_regs; |
242 | |
243 | /* |
244 | * Send the trace to the ring-buffer. |
245 | * @return the original return address. |
246 | */ |
247 | static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs, |
248 | unsigned long frame_pointer) |
249 | { |
250 | struct ftrace_graph_ret trace; |
251 | unsigned long ret; |
252 | |
253 | ftrace_pop_return_trace(trace: &trace, ret: &ret, frame_pointer); |
254 | #ifdef CONFIG_FUNCTION_GRAPH_RETVAL |
255 | trace.retval = fgraph_ret_regs_return_value(ret_regs); |
256 | #endif |
257 | trace.rettime = trace_clock_local(); |
258 | ftrace_graph_return(&trace); |
259 | /* |
260 | * The ftrace_graph_return() may still access the current |
261 | * ret_stack structure, we need to make sure the update of |
262 | * curr_ret_stack is after that. |
263 | */ |
264 | barrier(); |
265 | current->curr_ret_stack--; |
266 | |
267 | if (unlikely(!ret)) { |
268 | ftrace_graph_stop(); |
269 | WARN_ON(1); |
270 | /* Might as well panic. What else to do? */ |
271 | ret = (unsigned long)panic; |
272 | } |
273 | |
274 | return ret; |
275 | } |
276 | |
277 | /* |
278 | * After all architecures have selected HAVE_FUNCTION_GRAPH_RETVAL, we can |
279 | * leave only ftrace_return_to_handler(ret_regs). |
280 | */ |
281 | #ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL |
282 | unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs) |
283 | { |
284 | return __ftrace_return_to_handler(ret_regs, |
285 | frame_pointer: fgraph_ret_regs_frame_pointer(ret_regs)); |
286 | } |
287 | #else |
288 | unsigned long ftrace_return_to_handler(unsigned long frame_pointer) |
289 | { |
290 | return __ftrace_return_to_handler(NULL, frame_pointer); |
291 | } |
292 | #endif |
293 | |
294 | /** |
295 | * ftrace_graph_get_ret_stack - return the entry of the shadow stack |
296 | * @task: The task to read the shadow stack from |
297 | * @idx: Index down the shadow stack |
298 | * |
299 | * Return the ret_struct on the shadow stack of the @task at the |
300 | * call graph at @idx starting with zero. If @idx is zero, it |
301 | * will return the last saved ret_stack entry. If it is greater than |
302 | * zero, it will return the corresponding ret_stack for the depth |
303 | * of saved return addresses. |
304 | */ |
305 | struct ftrace_ret_stack * |
306 | ftrace_graph_get_ret_stack(struct task_struct *task, int idx) |
307 | { |
308 | idx = task->curr_ret_stack - idx; |
309 | |
310 | if (idx >= 0 && idx <= task->curr_ret_stack) |
311 | return &task->ret_stack[idx]; |
312 | |
313 | return NULL; |
314 | } |
315 | |
316 | /** |
317 | * ftrace_graph_ret_addr - convert a potentially modified stack return address |
318 | * to its original value |
319 | * |
320 | * This function can be called by stack unwinding code to convert a found stack |
321 | * return address ('ret') to its original value, in case the function graph |
322 | * tracer has modified it to be 'return_to_handler'. If the address hasn't |
323 | * been modified, the unchanged value of 'ret' is returned. |
324 | * |
325 | * 'idx' is a state variable which should be initialized by the caller to zero |
326 | * before the first call. |
327 | * |
328 | * 'retp' is a pointer to the return address on the stack. It's ignored if |
329 | * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined. |
330 | */ |
331 | #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR |
332 | unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, |
333 | unsigned long ret, unsigned long *retp) |
334 | { |
335 | int index = task->curr_ret_stack; |
336 | int i; |
337 | |
338 | if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler)) |
339 | return ret; |
340 | |
341 | if (index < 0) |
342 | return ret; |
343 | |
344 | for (i = 0; i <= index; i++) |
345 | if (task->ret_stack[i].retp == retp) |
346 | return task->ret_stack[i].ret; |
347 | |
348 | return ret; |
349 | } |
350 | #else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */ |
351 | unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, |
352 | unsigned long ret, unsigned long *retp) |
353 | { |
354 | int task_idx; |
355 | |
356 | if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler)) |
357 | return ret; |
358 | |
359 | task_idx = task->curr_ret_stack; |
360 | |
361 | if (!task->ret_stack || task_idx < *idx) |
362 | return ret; |
363 | |
364 | task_idx -= *idx; |
365 | (*idx)++; |
366 | |
367 | return task->ret_stack[task_idx].ret; |
368 | } |
369 | #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */ |
370 | |
371 | static struct ftrace_ops graph_ops = { |
372 | .func = ftrace_graph_func, |
373 | .flags = FTRACE_OPS_FL_INITIALIZED | |
374 | FTRACE_OPS_FL_PID | |
375 | FTRACE_OPS_GRAPH_STUB, |
376 | #ifdef FTRACE_GRAPH_TRAMP_ADDR |
377 | .trampoline = FTRACE_GRAPH_TRAMP_ADDR, |
378 | /* trampoline_size is only needed for dynamically allocated tramps */ |
379 | #endif |
380 | ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash) |
381 | }; |
382 | |
383 | void ftrace_graph_sleep_time_control(bool enable) |
384 | { |
385 | fgraph_sleep_time = enable; |
386 | } |
387 | |
388 | int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace) |
389 | { |
390 | return 0; |
391 | } |
392 | |
393 | /* |
394 | * Simply points to ftrace_stub, but with the proper protocol. |
395 | * Defined by the linker script in linux/vmlinux.lds.h |
396 | */ |
397 | extern void ftrace_stub_graph(struct ftrace_graph_ret *); |
398 | |
399 | /* The callbacks that hook a function */ |
400 | trace_func_graph_ret_t ftrace_graph_return = ftrace_stub_graph; |
401 | trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub; |
402 | static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub; |
403 | |
404 | /* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */ |
405 | static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) |
406 | { |
407 | int i; |
408 | int ret = 0; |
409 | int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE; |
410 | struct task_struct *g, *t; |
411 | |
412 | for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) { |
413 | ret_stack_list[i] = |
414 | kmalloc_array(FTRACE_RETFUNC_DEPTH, |
415 | size: sizeof(struct ftrace_ret_stack), |
416 | GFP_KERNEL); |
417 | if (!ret_stack_list[i]) { |
418 | start = 0; |
419 | end = i; |
420 | ret = -ENOMEM; |
421 | goto free; |
422 | } |
423 | } |
424 | |
425 | rcu_read_lock(); |
426 | for_each_process_thread(g, t) { |
427 | if (start == end) { |
428 | ret = -EAGAIN; |
429 | goto unlock; |
430 | } |
431 | |
432 | if (t->ret_stack == NULL) { |
433 | atomic_set(v: &t->trace_overrun, i: 0); |
434 | t->curr_ret_stack = -1; |
435 | t->curr_ret_depth = -1; |
436 | /* Make sure the tasks see the -1 first: */ |
437 | smp_wmb(); |
438 | t->ret_stack = ret_stack_list[start++]; |
439 | } |
440 | } |
441 | |
442 | unlock: |
443 | rcu_read_unlock(); |
444 | free: |
445 | for (i = start; i < end; i++) |
446 | kfree(objp: ret_stack_list[i]); |
447 | return ret; |
448 | } |
449 | |
450 | static void |
451 | ftrace_graph_probe_sched_switch(void *ignore, bool preempt, |
452 | struct task_struct *prev, |
453 | struct task_struct *next, |
454 | unsigned int prev_state) |
455 | { |
456 | unsigned long long timestamp; |
457 | int index; |
458 | |
459 | /* |
460 | * Does the user want to count the time a function was asleep. |
461 | * If so, do not update the time stamps. |
462 | */ |
463 | if (fgraph_sleep_time) |
464 | return; |
465 | |
466 | timestamp = trace_clock_local(); |
467 | |
468 | prev->ftrace_timestamp = timestamp; |
469 | |
470 | /* only process tasks that we timestamped */ |
471 | if (!next->ftrace_timestamp) |
472 | return; |
473 | |
474 | /* |
475 | * Update all the counters in next to make up for the |
476 | * time next was sleeping. |
477 | */ |
478 | timestamp -= next->ftrace_timestamp; |
479 | |
480 | for (index = next->curr_ret_stack; index >= 0; index--) |
481 | next->ret_stack[index].calltime += timestamp; |
482 | } |
483 | |
484 | static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace) |
485 | { |
486 | if (!ftrace_ops_test(ops: &global_ops, ip: trace->func, NULL)) |
487 | return 0; |
488 | return __ftrace_graph_entry(trace); |
489 | } |
490 | |
491 | /* |
492 | * The function graph tracer should only trace the functions defined |
493 | * by set_ftrace_filter and set_ftrace_notrace. If another function |
494 | * tracer ops is registered, the graph tracer requires testing the |
495 | * function against the global ops, and not just trace any function |
496 | * that any ftrace_ops registered. |
497 | */ |
498 | void update_function_graph_func(void) |
499 | { |
500 | struct ftrace_ops *op; |
501 | bool do_test = false; |
502 | |
503 | /* |
504 | * The graph and global ops share the same set of functions |
505 | * to test. If any other ops is on the list, then |
506 | * the graph tracing needs to test if its the function |
507 | * it should call. |
508 | */ |
509 | do_for_each_ftrace_op(op, ftrace_ops_list) { |
510 | if (op != &global_ops && op != &graph_ops && |
511 | op != &ftrace_list_end) { |
512 | do_test = true; |
513 | /* in double loop, break out with goto */ |
514 | goto out; |
515 | } |
516 | } while_for_each_ftrace_op(op); |
517 | out: |
518 | if (do_test) |
519 | ftrace_graph_entry = ftrace_graph_entry_test; |
520 | else |
521 | ftrace_graph_entry = __ftrace_graph_entry; |
522 | } |
523 | |
524 | static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack); |
525 | |
526 | static void |
527 | graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack) |
528 | { |
529 | atomic_set(v: &t->trace_overrun, i: 0); |
530 | t->ftrace_timestamp = 0; |
531 | /* make curr_ret_stack visible before we add the ret_stack */ |
532 | smp_wmb(); |
533 | t->ret_stack = ret_stack; |
534 | } |
535 | |
536 | /* |
537 | * Allocate a return stack for the idle task. May be the first |
538 | * time through, or it may be done by CPU hotplug online. |
539 | */ |
540 | void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) |
541 | { |
542 | t->curr_ret_stack = -1; |
543 | t->curr_ret_depth = -1; |
544 | /* |
545 | * The idle task has no parent, it either has its own |
546 | * stack or no stack at all. |
547 | */ |
548 | if (t->ret_stack) |
549 | WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu)); |
550 | |
551 | if (ftrace_graph_active) { |
552 | struct ftrace_ret_stack *ret_stack; |
553 | |
554 | ret_stack = per_cpu(idle_ret_stack, cpu); |
555 | if (!ret_stack) { |
556 | ret_stack = |
557 | kmalloc_array(FTRACE_RETFUNC_DEPTH, |
558 | size: sizeof(struct ftrace_ret_stack), |
559 | GFP_KERNEL); |
560 | if (!ret_stack) |
561 | return; |
562 | per_cpu(idle_ret_stack, cpu) = ret_stack; |
563 | } |
564 | graph_init_task(t, ret_stack); |
565 | } |
566 | } |
567 | |
568 | /* Allocate a return stack for newly created task */ |
569 | void ftrace_graph_init_task(struct task_struct *t) |
570 | { |
571 | /* Make sure we do not use the parent ret_stack */ |
572 | t->ret_stack = NULL; |
573 | t->curr_ret_stack = -1; |
574 | t->curr_ret_depth = -1; |
575 | |
576 | if (ftrace_graph_active) { |
577 | struct ftrace_ret_stack *ret_stack; |
578 | |
579 | ret_stack = kmalloc_array(FTRACE_RETFUNC_DEPTH, |
580 | size: sizeof(struct ftrace_ret_stack), |
581 | GFP_KERNEL); |
582 | if (!ret_stack) |
583 | return; |
584 | graph_init_task(t, ret_stack); |
585 | } |
586 | } |
587 | |
588 | void ftrace_graph_exit_task(struct task_struct *t) |
589 | { |
590 | struct ftrace_ret_stack *ret_stack = t->ret_stack; |
591 | |
592 | t->ret_stack = NULL; |
593 | /* NULL must become visible to IRQs before we free it: */ |
594 | barrier(); |
595 | |
596 | kfree(objp: ret_stack); |
597 | } |
598 | |
599 | /* Allocate a return stack for each task */ |
600 | static int start_graph_tracing(void) |
601 | { |
602 | struct ftrace_ret_stack **ret_stack_list; |
603 | int ret, cpu; |
604 | |
605 | ret_stack_list = kmalloc_array(FTRACE_RETSTACK_ALLOC_SIZE, |
606 | size: sizeof(struct ftrace_ret_stack *), |
607 | GFP_KERNEL); |
608 | |
609 | if (!ret_stack_list) |
610 | return -ENOMEM; |
611 | |
612 | /* The cpu_boot init_task->ret_stack will never be freed */ |
613 | for_each_online_cpu(cpu) { |
614 | if (!idle_task(cpu)->ret_stack) |
615 | ftrace_graph_init_idle_task(t: idle_task(cpu), cpu); |
616 | } |
617 | |
618 | do { |
619 | ret = alloc_retstack_tasklist(ret_stack_list); |
620 | } while (ret == -EAGAIN); |
621 | |
622 | if (!ret) { |
623 | ret = register_trace_sched_switch(probe: ftrace_graph_probe_sched_switch, NULL); |
624 | if (ret) |
625 | pr_info("ftrace_graph: Couldn't activate tracepoint" |
626 | " probe to kernel_sched_switch\n" ); |
627 | } |
628 | |
629 | kfree(objp: ret_stack_list); |
630 | return ret; |
631 | } |
632 | |
633 | int register_ftrace_graph(struct fgraph_ops *gops) |
634 | { |
635 | int ret = 0; |
636 | |
637 | mutex_lock(&ftrace_lock); |
638 | |
639 | /* we currently allow only one tracer registered at a time */ |
640 | if (ftrace_graph_active) { |
641 | ret = -EBUSY; |
642 | goto out; |
643 | } |
644 | |
645 | register_pm_notifier(nb: &ftrace_suspend_notifier); |
646 | |
647 | ftrace_graph_active++; |
648 | ret = start_graph_tracing(); |
649 | if (ret) { |
650 | ftrace_graph_active--; |
651 | goto out; |
652 | } |
653 | |
654 | ftrace_graph_return = gops->retfunc; |
655 | |
656 | /* |
657 | * Update the indirect function to the entryfunc, and the |
658 | * function that gets called to the entry_test first. Then |
659 | * call the update fgraph entry function to determine if |
660 | * the entryfunc should be called directly or not. |
661 | */ |
662 | __ftrace_graph_entry = gops->entryfunc; |
663 | ftrace_graph_entry = ftrace_graph_entry_test; |
664 | update_function_graph_func(); |
665 | |
666 | ret = ftrace_startup(ops: &graph_ops, command: FTRACE_START_FUNC_RET); |
667 | out: |
668 | mutex_unlock(lock: &ftrace_lock); |
669 | return ret; |
670 | } |
671 | |
672 | void unregister_ftrace_graph(struct fgraph_ops *gops) |
673 | { |
674 | mutex_lock(&ftrace_lock); |
675 | |
676 | if (unlikely(!ftrace_graph_active)) |
677 | goto out; |
678 | |
679 | ftrace_graph_active--; |
680 | ftrace_graph_return = ftrace_stub_graph; |
681 | ftrace_graph_entry = ftrace_graph_entry_stub; |
682 | __ftrace_graph_entry = ftrace_graph_entry_stub; |
683 | ftrace_shutdown(ops: &graph_ops, command: FTRACE_STOP_FUNC_RET); |
684 | unregister_pm_notifier(nb: &ftrace_suspend_notifier); |
685 | unregister_trace_sched_switch(probe: ftrace_graph_probe_sched_switch, NULL); |
686 | |
687 | out: |
688 | mutex_unlock(lock: &ftrace_lock); |
689 | } |
690 | |