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TOMOYO Linux Cross Reference
Linux/kernel/trace/trace_functions_graph.c

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  1 /*
  2  *
  3  * Function graph tracer.
  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  */
  9 #include <linux/uaccess.h>
 10 #include <linux/ftrace.h>
 11 #include <linux/interrupt.h>
 12 #include <linux/slab.h>
 13 #include <linux/fs.h>
 14 
 15 #include "trace.h"
 16 #include "trace_output.h"
 17 
 18 static bool kill_ftrace_graph;
 19 
 20 /**
 21  * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called
 22  *
 23  * ftrace_graph_stop() is called when a severe error is detected in
 24  * the function graph tracing. This function is called by the critical
 25  * paths of function graph to keep those paths from doing any more harm.
 26  */
 27 bool ftrace_graph_is_dead(void)
 28 {
 29         return kill_ftrace_graph;
 30 }
 31 
 32 /**
 33  * ftrace_graph_stop - set to permanently disable function graph tracincg
 34  *
 35  * In case of an error int function graph tracing, this is called
 36  * to try to keep function graph tracing from causing any more harm.
 37  * Usually this is pretty severe and this is called to try to at least
 38  * get a warning out to the user.
 39  */
 40 void ftrace_graph_stop(void)
 41 {
 42         kill_ftrace_graph = true;
 43 }
 44 
 45 /* When set, irq functions will be ignored */
 46 static int ftrace_graph_skip_irqs;
 47 
 48 struct fgraph_cpu_data {
 49         pid_t           last_pid;
 50         int             depth;
 51         int             depth_irq;
 52         int             ignore;
 53         unsigned long   enter_funcs[FTRACE_RETFUNC_DEPTH];
 54 };
 55 
 56 struct fgraph_data {
 57         struct fgraph_cpu_data __percpu *cpu_data;
 58 
 59         /* Place to preserve last processed entry. */
 60         struct ftrace_graph_ent_entry   ent;
 61         struct ftrace_graph_ret_entry   ret;
 62         int                             failed;
 63         int                             cpu;
 64 };
 65 
 66 #define TRACE_GRAPH_INDENT      2
 67 
 68 unsigned int fgraph_max_depth;
 69 
 70 static struct tracer_opt trace_opts[] = {
 71         /* Display overruns? (for self-debug purpose) */
 72         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
 73         /* Display CPU ? */
 74         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
 75         /* Display Overhead ? */
 76         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
 77         /* Display proc name/pid */
 78         { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
 79         /* Display duration of execution */
 80         { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
 81         /* Display absolute time of an entry */
 82         { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
 83         /* Display interrupts */
 84         { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
 85         /* Display function name after trailing } */
 86         { TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) },
 87         /* Include sleep time (scheduled out) between entry and return */
 88         { TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },
 89         /* Include time within nested functions */
 90         { TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) },
 91         { } /* Empty entry */
 92 };
 93 
 94 static struct tracer_flags tracer_flags = {
 95         /* Don't display overruns, proc, or tail by default */
 96         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
 97                TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS |
 98                TRACE_GRAPH_SLEEP_TIME | TRACE_GRAPH_GRAPH_TIME,
 99         .opts = trace_opts
100 };
101 
102 static struct trace_array *graph_array;
103 
104 /*
105  * DURATION column is being also used to display IRQ signs,
106  * following values are used by print_graph_irq and others
107  * to fill in space into DURATION column.
108  */
109 enum {
110         FLAGS_FILL_FULL  = 1 << TRACE_GRAPH_PRINT_FILL_SHIFT,
111         FLAGS_FILL_START = 2 << TRACE_GRAPH_PRINT_FILL_SHIFT,
112         FLAGS_FILL_END   = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT,
113 };
114 
115 static void
116 print_graph_duration(struct trace_array *tr, unsigned long long duration,
117                      struct trace_seq *s, u32 flags);
118 
119 /* Add a function return address to the trace stack on thread info.*/
120 int
121 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
122                          unsigned long frame_pointer, unsigned long *retp)
123 {
124         unsigned long long calltime;
125         int index;
126 
127         if (unlikely(ftrace_graph_is_dead()))
128                 return -EBUSY;
129 
130         if (!current->ret_stack)
131                 return -EBUSY;
132 
133         /*
134          * We must make sure the ret_stack is tested before we read
135          * anything else.
136          */
137         smp_rmb();
138 
139         /* The return trace stack is full */
140         if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
141                 atomic_inc(&current->trace_overrun);
142                 return -EBUSY;
143         }
144 
145         /*
146          * The curr_ret_stack is an index to ftrace return stack of
147          * current task.  Its value should be in [0, FTRACE_RETFUNC_
148          * DEPTH) when the function graph tracer is used.  To support
149          * filtering out specific functions, it makes the index
150          * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
151          * so when it sees a negative index the ftrace will ignore
152          * the record.  And the index gets recovered when returning
153          * from the filtered function by adding the FTRACE_NOTRACE_
154          * DEPTH and then it'll continue to record functions normally.
155          *
156          * The curr_ret_stack is initialized to -1 and get increased
157          * in this function.  So it can be less than -1 only if it was
158          * filtered out via ftrace_graph_notrace_addr() which can be
159          * set from set_graph_notrace file in tracefs by user.
160          */
161         if (current->curr_ret_stack < -1)
162                 return -EBUSY;
163 
164         calltime = trace_clock_local();
165 
166         index = ++current->curr_ret_stack;
167         if (ftrace_graph_notrace_addr(func))
168                 current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
169         barrier();
170         current->ret_stack[index].ret = ret;
171         current->ret_stack[index].func = func;
172         current->ret_stack[index].calltime = calltime;
173 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
174         current->ret_stack[index].fp = frame_pointer;
175 #endif
176 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
177         current->ret_stack[index].retp = retp;
178 #endif
179         *depth = current->curr_ret_stack;
180 
181         return 0;
182 }
183 
184 /* Retrieve a function return address to the trace stack on thread info.*/
185 static void
186 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
187                         unsigned long frame_pointer)
188 {
189         int index;
190 
191         index = current->curr_ret_stack;
192 
193         /*
194          * A negative index here means that it's just returned from a
195          * notrace'd function.  Recover index to get an original
196          * return address.  See ftrace_push_return_trace().
197          *
198          * TODO: Need to check whether the stack gets corrupted.
199          */
200         if (index < 0)
201                 index += FTRACE_NOTRACE_DEPTH;
202 
203         if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
204                 ftrace_graph_stop();
205                 WARN_ON(1);
206                 /* Might as well panic, otherwise we have no where to go */
207                 *ret = (unsigned long)panic;
208                 return;
209         }
210 
211 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
212         /*
213          * The arch may choose to record the frame pointer used
214          * and check it here to make sure that it is what we expect it
215          * to be. If gcc does not set the place holder of the return
216          * address in the frame pointer, and does a copy instead, then
217          * the function graph trace will fail. This test detects this
218          * case.
219          *
220          * Currently, x86_32 with optimize for size (-Os) makes the latest
221          * gcc do the above.
222          *
223          * Note, -mfentry does not use frame pointers, and this test
224          *  is not needed if CC_USING_FENTRY is set.
225          */
226         if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
227                 ftrace_graph_stop();
228                 WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
229                      "  from func %ps return to %lx\n",
230                      current->ret_stack[index].fp,
231                      frame_pointer,
232                      (void *)current->ret_stack[index].func,
233                      current->ret_stack[index].ret);
234                 *ret = (unsigned long)panic;
235                 return;
236         }
237 #endif
238 
239         *ret = current->ret_stack[index].ret;
240         trace->func = current->ret_stack[index].func;
241         trace->calltime = current->ret_stack[index].calltime;
242         trace->overrun = atomic_read(&current->trace_overrun);
243         trace->depth = index;
244 }
245 
246 /*
247  * Send the trace to the ring-buffer.
248  * @return the original return address.
249  */
250 unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
251 {
252         struct ftrace_graph_ret trace;
253         unsigned long ret;
254 
255         ftrace_pop_return_trace(&trace, &ret, frame_pointer);
256         trace.rettime = trace_clock_local();
257         barrier();
258         current->curr_ret_stack--;
259         /*
260          * The curr_ret_stack can be less than -1 only if it was
261          * filtered out and it's about to return from the function.
262          * Recover the index and continue to trace normal functions.
263          */
264         if (current->curr_ret_stack < -1) {
265                 current->curr_ret_stack += FTRACE_NOTRACE_DEPTH;
266                 return ret;
267         }
268 
269         /*
270          * The trace should run after decrementing the ret counter
271          * in case an interrupt were to come in. We don't want to
272          * lose the interrupt if max_depth is set.
273          */
274         ftrace_graph_return(&trace);
275 
276         if (unlikely(!ret)) {
277                 ftrace_graph_stop();
278                 WARN_ON(1);
279                 /* Might as well panic. What else to do? */
280                 ret = (unsigned long)panic;
281         }
282 
283         return ret;
284 }
285 
286 /**
287  * ftrace_graph_ret_addr - convert a potentially modified stack return address
288  *                         to its original value
289  *
290  * This function can be called by stack unwinding code to convert a found stack
291  * return address ('ret') to its original value, in case the function graph
292  * tracer has modified it to be 'return_to_handler'.  If the address hasn't
293  * been modified, the unchanged value of 'ret' is returned.
294  *
295  * 'idx' is a state variable which should be initialized by the caller to zero
296  * before the first call.
297  *
298  * 'retp' is a pointer to the return address on the stack.  It's ignored if
299  * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
300  */
301 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
302 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
303                                     unsigned long ret, unsigned long *retp)
304 {
305         int index = task->curr_ret_stack;
306         int i;
307 
308         if (ret != (unsigned long)return_to_handler)
309                 return ret;
310 
311         if (index < -1)
312                 index += FTRACE_NOTRACE_DEPTH;
313 
314         if (index < 0)
315                 return ret;
316 
317         for (i = 0; i <= index; i++)
318                 if (task->ret_stack[i].retp == retp)
319                         return task->ret_stack[i].ret;
320 
321         return ret;
322 }
323 #else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
324 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
325                                     unsigned long ret, unsigned long *retp)
326 {
327         int task_idx;
328 
329         if (ret != (unsigned long)return_to_handler)
330                 return ret;
331 
332         task_idx = task->curr_ret_stack;
333 
334         if (!task->ret_stack || task_idx < *idx)
335                 return ret;
336 
337         task_idx -= *idx;
338         (*idx)++;
339 
340         return task->ret_stack[task_idx].ret;
341 }
342 #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
343 
344 int __trace_graph_entry(struct trace_array *tr,
345                                 struct ftrace_graph_ent *trace,
346                                 unsigned long flags,
347                                 int pc)
348 {
349         struct trace_event_call *call = &event_funcgraph_entry;
350         struct ring_buffer_event *event;
351         struct ring_buffer *buffer = tr->trace_buffer.buffer;
352         struct ftrace_graph_ent_entry *entry;
353 
354         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
355                                           sizeof(*entry), flags, pc);
356         if (!event)
357                 return 0;
358         entry   = ring_buffer_event_data(event);
359         entry->graph_ent                        = *trace;
360         if (!call_filter_check_discard(call, entry, buffer, event))
361                 trace_buffer_unlock_commit_nostack(buffer, event);
362 
363         return 1;
364 }
365 
366 static inline int ftrace_graph_ignore_irqs(void)
367 {
368         if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
369                 return 0;
370 
371         return in_irq();
372 }
373 
374 int trace_graph_entry(struct ftrace_graph_ent *trace)
375 {
376         struct trace_array *tr = graph_array;
377         struct trace_array_cpu *data;
378         unsigned long flags;
379         long disabled;
380         int ret;
381         int cpu;
382         int pc;
383 
384         if (!ftrace_trace_task(tr))
385                 return 0;
386 
387         if (ftrace_graph_ignore_func(trace))
388                 return 0;
389 
390         if (ftrace_graph_ignore_irqs())
391                 return 0;
392 
393         /*
394          * Do not trace a function if it's filtered by set_graph_notrace.
395          * Make the index of ret stack negative to indicate that it should
396          * ignore further functions.  But it needs its own ret stack entry
397          * to recover the original index in order to continue tracing after
398          * returning from the function.
399          */
400         if (ftrace_graph_notrace_addr(trace->func))
401                 return 1;
402 
403         /*
404          * Stop here if tracing_threshold is set. We only write function return
405          * events to the ring buffer.
406          */
407         if (tracing_thresh)
408                 return 1;
409 
410         local_irq_save(flags);
411         cpu = raw_smp_processor_id();
412         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
413         disabled = atomic_inc_return(&data->disabled);
414         if (likely(disabled == 1)) {
415                 pc = preempt_count();
416                 ret = __trace_graph_entry(tr, trace, flags, pc);
417         } else {
418                 ret = 0;
419         }
420 
421         atomic_dec(&data->disabled);
422         local_irq_restore(flags);
423 
424         return ret;
425 }
426 
427 static void
428 __trace_graph_function(struct trace_array *tr,
429                 unsigned long ip, unsigned long flags, int pc)
430 {
431         u64 time = trace_clock_local();
432         struct ftrace_graph_ent ent = {
433                 .func  = ip,
434                 .depth = 0,
435         };
436         struct ftrace_graph_ret ret = {
437                 .func     = ip,
438                 .depth    = 0,
439                 .calltime = time,
440                 .rettime  = time,
441         };
442 
443         __trace_graph_entry(tr, &ent, flags, pc);
444         __trace_graph_return(tr, &ret, flags, pc);
445 }
446 
447 void
448 trace_graph_function(struct trace_array *tr,
449                 unsigned long ip, unsigned long parent_ip,
450                 unsigned long flags, int pc)
451 {
452         __trace_graph_function(tr, ip, flags, pc);
453 }
454 
455 void __trace_graph_return(struct trace_array *tr,
456                                 struct ftrace_graph_ret *trace,
457                                 unsigned long flags,
458                                 int pc)
459 {
460         struct trace_event_call *call = &event_funcgraph_exit;
461         struct ring_buffer_event *event;
462         struct ring_buffer *buffer = tr->trace_buffer.buffer;
463         struct ftrace_graph_ret_entry *entry;
464 
465         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
466                                           sizeof(*entry), flags, pc);
467         if (!event)
468                 return;
469         entry   = ring_buffer_event_data(event);
470         entry->ret                              = *trace;
471         if (!call_filter_check_discard(call, entry, buffer, event))
472                 trace_buffer_unlock_commit_nostack(buffer, event);
473 }
474 
475 void trace_graph_return(struct ftrace_graph_ret *trace)
476 {
477         struct trace_array *tr = graph_array;
478         struct trace_array_cpu *data;
479         unsigned long flags;
480         long disabled;
481         int cpu;
482         int pc;
483 
484         local_irq_save(flags);
485         cpu = raw_smp_processor_id();
486         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
487         disabled = atomic_inc_return(&data->disabled);
488         if (likely(disabled == 1)) {
489                 pc = preempt_count();
490                 __trace_graph_return(tr, trace, flags, pc);
491         }
492         atomic_dec(&data->disabled);
493         local_irq_restore(flags);
494 }
495 
496 void set_graph_array(struct trace_array *tr)
497 {
498         graph_array = tr;
499 
500         /* Make graph_array visible before we start tracing */
501 
502         smp_mb();
503 }
504 
505 static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
506 {
507         if (tracing_thresh &&
508             (trace->rettime - trace->calltime < tracing_thresh))
509                 return;
510         else
511                 trace_graph_return(trace);
512 }
513 
514 static int graph_trace_init(struct trace_array *tr)
515 {
516         int ret;
517 
518         set_graph_array(tr);
519         if (tracing_thresh)
520                 ret = register_ftrace_graph(&trace_graph_thresh_return,
521                                             &trace_graph_entry);
522         else
523                 ret = register_ftrace_graph(&trace_graph_return,
524                                             &trace_graph_entry);
525         if (ret)
526                 return ret;
527         tracing_start_cmdline_record();
528 
529         return 0;
530 }
531 
532 static void graph_trace_reset(struct trace_array *tr)
533 {
534         tracing_stop_cmdline_record();
535         unregister_ftrace_graph();
536 }
537 
538 static int graph_trace_update_thresh(struct trace_array *tr)
539 {
540         graph_trace_reset(tr);
541         return graph_trace_init(tr);
542 }
543 
544 static int max_bytes_for_cpu;
545 
546 static void print_graph_cpu(struct trace_seq *s, int cpu)
547 {
548         /*
549          * Start with a space character - to make it stand out
550          * to the right a bit when trace output is pasted into
551          * email:
552          */
553         trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
554 }
555 
556 #define TRACE_GRAPH_PROCINFO_LENGTH     14
557 
558 static void print_graph_proc(struct trace_seq *s, pid_t pid)
559 {
560         char comm[TASK_COMM_LEN];
561         /* sign + log10(MAX_INT) + '\0' */
562         char pid_str[11];
563         int spaces = 0;
564         int len;
565         int i;
566 
567         trace_find_cmdline(pid, comm);
568         comm[7] = '\0';
569         sprintf(pid_str, "%d", pid);
570 
571         /* 1 stands for the "-" character */
572         len = strlen(comm) + strlen(pid_str) + 1;
573 
574         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
575                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
576 
577         /* First spaces to align center */
578         for (i = 0; i < spaces / 2; i++)
579                 trace_seq_putc(s, ' ');
580 
581         trace_seq_printf(s, "%s-%s", comm, pid_str);
582 
583         /* Last spaces to align center */
584         for (i = 0; i < spaces - (spaces / 2); i++)
585                 trace_seq_putc(s, ' ');
586 }
587 
588 
589 static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
590 {
591         trace_seq_putc(s, ' ');
592         trace_print_lat_fmt(s, entry);
593 }
594 
595 /* If the pid changed since the last trace, output this event */
596 static void
597 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
598 {
599         pid_t prev_pid;
600         pid_t *last_pid;
601 
602         if (!data)
603                 return;
604 
605         last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
606 
607         if (*last_pid == pid)
608                 return;
609 
610         prev_pid = *last_pid;
611         *last_pid = pid;
612 
613         if (prev_pid == -1)
614                 return;
615 /*
616  * Context-switch trace line:
617 
618  ------------------------------------------
619  | 1)  migration/0--1  =>  sshd-1755
620  ------------------------------------------
621 
622  */
623         trace_seq_puts(s, " ------------------------------------------\n");
624         print_graph_cpu(s, cpu);
625         print_graph_proc(s, prev_pid);
626         trace_seq_puts(s, " => ");
627         print_graph_proc(s, pid);
628         trace_seq_puts(s, "\n ------------------------------------------\n\n");
629 }
630 
631 static struct ftrace_graph_ret_entry *
632 get_return_for_leaf(struct trace_iterator *iter,
633                 struct ftrace_graph_ent_entry *curr)
634 {
635         struct fgraph_data *data = iter->private;
636         struct ring_buffer_iter *ring_iter = NULL;
637         struct ring_buffer_event *event;
638         struct ftrace_graph_ret_entry *next;
639 
640         /*
641          * If the previous output failed to write to the seq buffer,
642          * then we just reuse the data from before.
643          */
644         if (data && data->failed) {
645                 curr = &data->ent;
646                 next = &data->ret;
647         } else {
648 
649                 ring_iter = trace_buffer_iter(iter, iter->cpu);
650 
651                 /* First peek to compare current entry and the next one */
652                 if (ring_iter)
653                         event = ring_buffer_iter_peek(ring_iter, NULL);
654                 else {
655                         /*
656                          * We need to consume the current entry to see
657                          * the next one.
658                          */
659                         ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
660                                             NULL, NULL);
661                         event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
662                                                  NULL, NULL);
663                 }
664 
665                 if (!event)
666                         return NULL;
667 
668                 next = ring_buffer_event_data(event);
669 
670                 if (data) {
671                         /*
672                          * Save current and next entries for later reference
673                          * if the output fails.
674                          */
675                         data->ent = *curr;
676                         /*
677                          * If the next event is not a return type, then
678                          * we only care about what type it is. Otherwise we can
679                          * safely copy the entire event.
680                          */
681                         if (next->ent.type == TRACE_GRAPH_RET)
682                                 data->ret = *next;
683                         else
684                                 data->ret.ent.type = next->ent.type;
685                 }
686         }
687 
688         if (next->ent.type != TRACE_GRAPH_RET)
689                 return NULL;
690 
691         if (curr->ent.pid != next->ent.pid ||
692                         curr->graph_ent.func != next->ret.func)
693                 return NULL;
694 
695         /* this is a leaf, now advance the iterator */
696         if (ring_iter)
697                 ring_buffer_read(ring_iter, NULL);
698 
699         return next;
700 }
701 
702 static void print_graph_abs_time(u64 t, struct trace_seq *s)
703 {
704         unsigned long usecs_rem;
705 
706         usecs_rem = do_div(t, NSEC_PER_SEC);
707         usecs_rem /= 1000;
708 
709         trace_seq_printf(s, "%5lu.%06lu |  ",
710                          (unsigned long)t, usecs_rem);
711 }
712 
713 static void
714 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
715                 enum trace_type type, int cpu, pid_t pid, u32 flags)
716 {
717         struct trace_array *tr = iter->tr;
718         struct trace_seq *s = &iter->seq;
719         struct trace_entry *ent = iter->ent;
720 
721         if (addr < (unsigned long)__irqentry_text_start ||
722                 addr >= (unsigned long)__irqentry_text_end)
723                 return;
724 
725         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
726                 /* Absolute time */
727                 if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
728                         print_graph_abs_time(iter->ts, s);
729 
730                 /* Cpu */
731                 if (flags & TRACE_GRAPH_PRINT_CPU)
732                         print_graph_cpu(s, cpu);
733 
734                 /* Proc */
735                 if (flags & TRACE_GRAPH_PRINT_PROC) {
736                         print_graph_proc(s, pid);
737                         trace_seq_puts(s, " | ");
738                 }
739 
740                 /* Latency format */
741                 if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
742                         print_graph_lat_fmt(s, ent);
743         }
744 
745         /* No overhead */
746         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_START);
747 
748         if (type == TRACE_GRAPH_ENT)
749                 trace_seq_puts(s, "==========>");
750         else
751                 trace_seq_puts(s, "<==========");
752 
753         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_END);
754         trace_seq_putc(s, '\n');
755 }
756 
757 void
758 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
759 {
760         unsigned long nsecs_rem = do_div(duration, 1000);
761         /* log10(ULONG_MAX) + '\0' */
762         char usecs_str[21];
763         char nsecs_str[5];
764         int len;
765         int i;
766 
767         sprintf(usecs_str, "%lu", (unsigned long) duration);
768 
769         /* Print msecs */
770         trace_seq_printf(s, "%s", usecs_str);
771 
772         len = strlen(usecs_str);
773 
774         /* Print nsecs (we don't want to exceed 7 numbers) */
775         if (len < 7) {
776                 size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);
777 
778                 snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
779                 trace_seq_printf(s, ".%s", nsecs_str);
780                 len += strlen(nsecs_str) + 1;
781         }
782 
783         trace_seq_puts(s, " us ");
784 
785         /* Print remaining spaces to fit the row's width */
786         for (i = len; i < 8; i++)
787                 trace_seq_putc(s, ' ');
788 }
789 
790 static void
791 print_graph_duration(struct trace_array *tr, unsigned long long duration,
792                      struct trace_seq *s, u32 flags)
793 {
794         if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
795             !(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
796                 return;
797 
798         /* No real adata, just filling the column with spaces */
799         switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) {
800         case FLAGS_FILL_FULL:
801                 trace_seq_puts(s, "              |  ");
802                 return;
803         case FLAGS_FILL_START:
804                 trace_seq_puts(s, "  ");
805                 return;
806         case FLAGS_FILL_END:
807                 trace_seq_puts(s, " |");
808                 return;
809         }
810 
811         /* Signal a overhead of time execution to the output */
812         if (flags & TRACE_GRAPH_PRINT_OVERHEAD)
813                 trace_seq_printf(s, "%c ", trace_find_mark(duration));
814         else
815                 trace_seq_puts(s, "  ");
816 
817         trace_print_graph_duration(duration, s);
818         trace_seq_puts(s, "|  ");
819 }
820 
821 /* Case of a leaf function on its call entry */
822 static enum print_line_t
823 print_graph_entry_leaf(struct trace_iterator *iter,
824                 struct ftrace_graph_ent_entry *entry,
825                 struct ftrace_graph_ret_entry *ret_entry,
826                 struct trace_seq *s, u32 flags)
827 {
828         struct fgraph_data *data = iter->private;
829         struct trace_array *tr = iter->tr;
830         struct ftrace_graph_ret *graph_ret;
831         struct ftrace_graph_ent *call;
832         unsigned long long duration;
833         int i;
834 
835         graph_ret = &ret_entry->ret;
836         call = &entry->graph_ent;
837         duration = graph_ret->rettime - graph_ret->calltime;
838 
839         if (data) {
840                 struct fgraph_cpu_data *cpu_data;
841                 int cpu = iter->cpu;
842 
843                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
844 
845                 /* If a graph tracer ignored set_graph_notrace */
846                 if (call->depth < -1)
847                         call->depth += FTRACE_NOTRACE_DEPTH;
848 
849                 /*
850                  * Comments display at + 1 to depth. Since
851                  * this is a leaf function, keep the comments
852                  * equal to this depth.
853                  */
854                 cpu_data->depth = call->depth - 1;
855 
856                 /* No need to keep this function around for this depth */
857                 if (call->depth < FTRACE_RETFUNC_DEPTH &&
858                     !WARN_ON_ONCE(call->depth < 0))
859                         cpu_data->enter_funcs[call->depth] = 0;
860         }
861 
862         /* Overhead and duration */
863         print_graph_duration(tr, duration, s, flags);
864 
865         /* Function */
866         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
867                 trace_seq_putc(s, ' ');
868 
869         trace_seq_printf(s, "%ps();\n", (void *)call->func);
870 
871         return trace_handle_return(s);
872 }
873 
874 static enum print_line_t
875 print_graph_entry_nested(struct trace_iterator *iter,
876                          struct ftrace_graph_ent_entry *entry,
877                          struct trace_seq *s, int cpu, u32 flags)
878 {
879         struct ftrace_graph_ent *call = &entry->graph_ent;
880         struct fgraph_data *data = iter->private;
881         struct trace_array *tr = iter->tr;
882         int i;
883 
884         if (data) {
885                 struct fgraph_cpu_data *cpu_data;
886                 int cpu = iter->cpu;
887 
888                 /* If a graph tracer ignored set_graph_notrace */
889                 if (call->depth < -1)
890                         call->depth += FTRACE_NOTRACE_DEPTH;
891 
892                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
893                 cpu_data->depth = call->depth;
894 
895                 /* Save this function pointer to see if the exit matches */
896                 if (call->depth < FTRACE_RETFUNC_DEPTH &&
897                     !WARN_ON_ONCE(call->depth < 0))
898                         cpu_data->enter_funcs[call->depth] = call->func;
899         }
900 
901         /* No time */
902         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
903 
904         /* Function */
905         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
906                 trace_seq_putc(s, ' ');
907 
908         trace_seq_printf(s, "%ps() {\n", (void *)call->func);
909 
910         if (trace_seq_has_overflowed(s))
911                 return TRACE_TYPE_PARTIAL_LINE;
912 
913         /*
914          * we already consumed the current entry to check the next one
915          * and see if this is a leaf.
916          */
917         return TRACE_TYPE_NO_CONSUME;
918 }
919 
920 static void
921 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
922                      int type, unsigned long addr, u32 flags)
923 {
924         struct fgraph_data *data = iter->private;
925         struct trace_entry *ent = iter->ent;
926         struct trace_array *tr = iter->tr;
927         int cpu = iter->cpu;
928 
929         /* Pid */
930         verif_pid(s, ent->pid, cpu, data);
931 
932         if (type)
933                 /* Interrupt */
934                 print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
935 
936         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
937                 return;
938 
939         /* Absolute time */
940         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
941                 print_graph_abs_time(iter->ts, s);
942 
943         /* Cpu */
944         if (flags & TRACE_GRAPH_PRINT_CPU)
945                 print_graph_cpu(s, cpu);
946 
947         /* Proc */
948         if (flags & TRACE_GRAPH_PRINT_PROC) {
949                 print_graph_proc(s, ent->pid);
950                 trace_seq_puts(s, " | ");
951         }
952 
953         /* Latency format */
954         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
955                 print_graph_lat_fmt(s, ent);
956 
957         return;
958 }
959 
960 /*
961  * Entry check for irq code
962  *
963  * returns 1 if
964  *  - we are inside irq code
965  *  - we just entered irq code
966  *
967  * retunns 0 if
968  *  - funcgraph-interrupts option is set
969  *  - we are not inside irq code
970  */
971 static int
972 check_irq_entry(struct trace_iterator *iter, u32 flags,
973                 unsigned long addr, int depth)
974 {
975         int cpu = iter->cpu;
976         int *depth_irq;
977         struct fgraph_data *data = iter->private;
978 
979         /*
980          * If we are either displaying irqs, or we got called as
981          * a graph event and private data does not exist,
982          * then we bypass the irq check.
983          */
984         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
985             (!data))
986                 return 0;
987 
988         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
989 
990         /*
991          * We are inside the irq code
992          */
993         if (*depth_irq >= 0)
994                 return 1;
995 
996         if ((addr < (unsigned long)__irqentry_text_start) ||
997             (addr >= (unsigned long)__irqentry_text_end))
998                 return 0;
999 
1000         /*
1001          * We are entering irq code.
1002          */
1003         *depth_irq = depth;
1004         return 1;
1005 }
1006 
1007 /*
1008  * Return check for irq code
1009  *
1010  * returns 1 if
1011  *  - we are inside irq code
1012  *  - we just left irq code
1013  *
1014  * returns 0 if
1015  *  - funcgraph-interrupts option is set
1016  *  - we are not inside irq code
1017  */
1018 static int
1019 check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
1020 {
1021         int cpu = iter->cpu;
1022         int *depth_irq;
1023         struct fgraph_data *data = iter->private;
1024 
1025         /*
1026          * If we are either displaying irqs, or we got called as
1027          * a graph event and private data does not exist,
1028          * then we bypass the irq check.
1029          */
1030         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
1031             (!data))
1032                 return 0;
1033 
1034         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1035 
1036         /*
1037          * We are not inside the irq code.
1038          */
1039         if (*depth_irq == -1)
1040                 return 0;
1041 
1042         /*
1043          * We are inside the irq code, and this is returning entry.
1044          * Let's not trace it and clear the entry depth, since
1045          * we are out of irq code.
1046          *
1047          * This condition ensures that we 'leave the irq code' once
1048          * we are out of the entry depth. Thus protecting us from
1049          * the RETURN entry loss.
1050          */
1051         if (*depth_irq >= depth) {
1052                 *depth_irq = -1;
1053                 return 1;
1054         }
1055 
1056         /*
1057          * We are inside the irq code, and this is not the entry.
1058          */
1059         return 1;
1060 }
1061 
1062 static enum print_line_t
1063 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
1064                         struct trace_iterator *iter, u32 flags)
1065 {
1066         struct fgraph_data *data = iter->private;
1067         struct ftrace_graph_ent *call = &field->graph_ent;
1068         struct ftrace_graph_ret_entry *leaf_ret;
1069         static enum print_line_t ret;
1070         int cpu = iter->cpu;
1071 
1072         if (check_irq_entry(iter, flags, call->func, call->depth))
1073                 return TRACE_TYPE_HANDLED;
1074 
1075         print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags);
1076 
1077         leaf_ret = get_return_for_leaf(iter, field);
1078         if (leaf_ret)
1079                 ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
1080         else
1081                 ret = print_graph_entry_nested(iter, field, s, cpu, flags);
1082 
1083         if (data) {
1084                 /*
1085                  * If we failed to write our output, then we need to make
1086                  * note of it. Because we already consumed our entry.
1087                  */
1088                 if (s->full) {
1089                         data->failed = 1;
1090                         data->cpu = cpu;
1091                 } else
1092                         data->failed = 0;
1093         }
1094 
1095         return ret;
1096 }
1097 
1098 static enum print_line_t
1099 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
1100                    struct trace_entry *ent, struct trace_iterator *iter,
1101                    u32 flags)
1102 {
1103         unsigned long long duration = trace->rettime - trace->calltime;
1104         struct fgraph_data *data = iter->private;
1105         struct trace_array *tr = iter->tr;
1106         pid_t pid = ent->pid;
1107         int cpu = iter->cpu;
1108         int func_match = 1;
1109         int i;
1110 
1111         if (check_irq_return(iter, flags, trace->depth))
1112                 return TRACE_TYPE_HANDLED;
1113 
1114         if (data) {
1115                 struct fgraph_cpu_data *cpu_data;
1116                 int cpu = iter->cpu;
1117 
1118                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
1119 
1120                 /*
1121                  * Comments display at + 1 to depth. This is the
1122                  * return from a function, we now want the comments
1123                  * to display at the same level of the bracket.
1124                  */
1125                 cpu_data->depth = trace->depth - 1;
1126 
1127                 if (trace->depth < FTRACE_RETFUNC_DEPTH &&
1128                     !WARN_ON_ONCE(trace->depth < 0)) {
1129                         if (cpu_data->enter_funcs[trace->depth] != trace->func)
1130                                 func_match = 0;
1131                         cpu_data->enter_funcs[trace->depth] = 0;
1132                 }
1133         }
1134 
1135         print_graph_prologue(iter, s, 0, 0, flags);
1136 
1137         /* Overhead and duration */
1138         print_graph_duration(tr, duration, s, flags);
1139 
1140         /* Closing brace */
1141         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
1142                 trace_seq_putc(s, ' ');
1143 
1144         /*
1145          * If the return function does not have a matching entry,
1146          * then the entry was lost. Instead of just printing
1147          * the '}' and letting the user guess what function this
1148          * belongs to, write out the function name. Always do
1149          * that if the funcgraph-tail option is enabled.
1150          */
1151         if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
1152                 trace_seq_puts(s, "}\n");
1153         else
1154                 trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
1155 
1156         /* Overrun */
1157         if (flags & TRACE_GRAPH_PRINT_OVERRUN)
1158                 trace_seq_printf(s, " (Overruns: %lu)\n",
1159                                  trace->overrun);
1160 
1161         print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
1162                         cpu, pid, flags);
1163 
1164         return trace_handle_return(s);
1165 }
1166 
1167 static enum print_line_t
1168 print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
1169                     struct trace_iterator *iter, u32 flags)
1170 {
1171         struct trace_array *tr = iter->tr;
1172         unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK);
1173         struct fgraph_data *data = iter->private;
1174         struct trace_event *event;
1175         int depth = 0;
1176         int ret;
1177         int i;
1178 
1179         if (data)
1180                 depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;
1181 
1182         print_graph_prologue(iter, s, 0, 0, flags);
1183 
1184         /* No time */
1185         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
1186 
1187         /* Indentation */
1188         if (depth > 0)
1189                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++)
1190                         trace_seq_putc(s, ' ');
1191 
1192         /* The comment */
1193         trace_seq_puts(s, "/* ");
1194 
1195         switch (iter->ent->type) {
1196         case TRACE_BPUTS:
1197                 ret = trace_print_bputs_msg_only(iter);
1198                 if (ret != TRACE_TYPE_HANDLED)
1199                         return ret;
1200                 break;
1201         case TRACE_BPRINT:
1202                 ret = trace_print_bprintk_msg_only(iter);
1203                 if (ret != TRACE_TYPE_HANDLED)
1204                         return ret;
1205                 break;
1206         case TRACE_PRINT:
1207                 ret = trace_print_printk_msg_only(iter);
1208                 if (ret != TRACE_TYPE_HANDLED)
1209                         return ret;
1210                 break;
1211         default:
1212                 event = ftrace_find_event(ent->type);
1213                 if (!event)
1214                         return TRACE_TYPE_UNHANDLED;
1215 
1216                 ret = event->funcs->trace(iter, sym_flags, event);
1217                 if (ret != TRACE_TYPE_HANDLED)
1218                         return ret;
1219         }
1220 
1221         if (trace_seq_has_overflowed(s))
1222                 goto out;
1223 
1224         /* Strip ending newline */
1225         if (s->buffer[s->seq.len - 1] == '\n') {
1226                 s->buffer[s->seq.len - 1] = '\0';
1227                 s->seq.len--;
1228         }
1229 
1230         trace_seq_puts(s, " */\n");
1231  out:
1232         return trace_handle_return(s);
1233 }
1234 
1235 
1236 enum print_line_t
1237 print_graph_function_flags(struct trace_iterator *iter, u32 flags)
1238 {
1239         struct ftrace_graph_ent_entry *field;
1240         struct fgraph_data *data = iter->private;
1241         struct trace_entry *entry = iter->ent;
1242         struct trace_seq *s = &iter->seq;
1243         int cpu = iter->cpu;
1244         int ret;
1245 
1246         if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
1247                 per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
1248                 return TRACE_TYPE_HANDLED;
1249         }
1250 
1251         /*
1252          * If the last output failed, there's a possibility we need
1253          * to print out the missing entry which would never go out.
1254          */
1255         if (data && data->failed) {
1256                 field = &data->ent;
1257                 iter->cpu = data->cpu;
1258                 ret = print_graph_entry(field, s, iter, flags);
1259                 if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
1260                         per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
1261                         ret = TRACE_TYPE_NO_CONSUME;
1262                 }
1263                 iter->cpu = cpu;
1264                 return ret;
1265         }
1266 
1267         switch (entry->type) {
1268         case TRACE_GRAPH_ENT: {
1269                 /*
1270                  * print_graph_entry() may consume the current event,
1271                  * thus @field may become invalid, so we need to save it.
1272                  * sizeof(struct ftrace_graph_ent_entry) is very small,
1273                  * it can be safely saved at the stack.
1274                  */
1275                 struct ftrace_graph_ent_entry saved;
1276                 trace_assign_type(field, entry);
1277                 saved = *field;
1278                 return print_graph_entry(&saved, s, iter, flags);
1279         }
1280         case TRACE_GRAPH_RET: {
1281                 struct ftrace_graph_ret_entry *field;
1282                 trace_assign_type(field, entry);
1283                 return print_graph_return(&field->ret, s, entry, iter, flags);
1284         }
1285         case TRACE_STACK:
1286         case TRACE_FN:
1287                 /* dont trace stack and functions as comments */
1288                 return TRACE_TYPE_UNHANDLED;
1289 
1290         default:
1291                 return print_graph_comment(s, entry, iter, flags);
1292         }
1293 
1294         return TRACE_TYPE_HANDLED;
1295 }
1296 
1297 static enum print_line_t
1298 print_graph_function(struct trace_iterator *iter)
1299 {
1300         return print_graph_function_flags(iter, tracer_flags.val);
1301 }
1302 
1303 static enum print_line_t
1304 print_graph_function_event(struct trace_iterator *iter, int flags,
1305                            struct trace_event *event)
1306 {
1307         return print_graph_function(iter);
1308 }
1309 
1310 static void print_lat_header(struct seq_file *s, u32 flags)
1311 {
1312         static const char spaces[] = "                " /* 16 spaces */
1313                 "    "                                  /* 4 spaces */
1314                 "                 ";                    /* 17 spaces */
1315         int size = 0;
1316 
1317         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1318                 size += 16;
1319         if (flags & TRACE_GRAPH_PRINT_CPU)
1320                 size += 4;
1321         if (flags & TRACE_GRAPH_PRINT_PROC)
1322                 size += 17;
1323 
1324         seq_printf(s, "#%.*s  _-----=> irqs-off        \n", size, spaces);
1325         seq_printf(s, "#%.*s / _----=> need-resched    \n", size, spaces);
1326         seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
1327         seq_printf(s, "#%.*s|| / _--=> preempt-depth   \n", size, spaces);
1328         seq_printf(s, "#%.*s||| /                      \n", size, spaces);
1329 }
1330 
1331 static void __print_graph_headers_flags(struct trace_array *tr,
1332                                         struct seq_file *s, u32 flags)
1333 {
1334         int lat = tr->trace_flags & TRACE_ITER_LATENCY_FMT;
1335 
1336         if (lat)
1337                 print_lat_header(s, flags);
1338 
1339         /* 1st line */
1340         seq_putc(s, '#');
1341         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1342                 seq_puts(s, "     TIME       ");
1343         if (flags & TRACE_GRAPH_PRINT_CPU)
1344                 seq_puts(s, " CPU");
1345         if (flags & TRACE_GRAPH_PRINT_PROC)
1346                 seq_puts(s, "  TASK/PID       ");
1347         if (lat)
1348                 seq_puts(s, "||||");
1349         if (flags & TRACE_GRAPH_PRINT_DURATION)
1350                 seq_puts(s, "  DURATION   ");
1351         seq_puts(s, "               FUNCTION CALLS\n");
1352 
1353         /* 2nd line */
1354         seq_putc(s, '#');
1355         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1356                 seq_puts(s, "      |         ");
1357         if (flags & TRACE_GRAPH_PRINT_CPU)
1358                 seq_puts(s, " |  ");
1359         if (flags & TRACE_GRAPH_PRINT_PROC)
1360                 seq_puts(s, "   |    |        ");
1361         if (lat)
1362                 seq_puts(s, "||||");
1363         if (flags & TRACE_GRAPH_PRINT_DURATION)
1364                 seq_puts(s, "   |   |      ");
1365         seq_puts(s, "               |   |   |   |\n");
1366 }
1367 
1368 static void print_graph_headers(struct seq_file *s)
1369 {
1370         print_graph_headers_flags(s, tracer_flags.val);
1371 }
1372 
1373 void print_graph_headers_flags(struct seq_file *s, u32 flags)
1374 {
1375         struct trace_iterator *iter = s->private;
1376         struct trace_array *tr = iter->tr;
1377 
1378         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
1379                 return;
1380 
1381         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) {
1382                 /* print nothing if the buffers are empty */
1383                 if (trace_empty(iter))
1384                         return;
1385 
1386                 print_trace_header(s, iter);
1387         }
1388 
1389         __print_graph_headers_flags(tr, s, flags);
1390 }
1391 
1392 void graph_trace_open(struct trace_iterator *iter)
1393 {
1394         /* pid and depth on the last trace processed */
1395         struct fgraph_data *data;
1396         gfp_t gfpflags;
1397         int cpu;
1398 
1399         iter->private = NULL;
1400 
1401         /* We can be called in atomic context via ftrace_dump() */
1402         gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
1403 
1404         data = kzalloc(sizeof(*data), gfpflags);
1405         if (!data)
1406                 goto out_err;
1407 
1408         data->cpu_data = alloc_percpu_gfp(struct fgraph_cpu_data, gfpflags);
1409         if (!data->cpu_data)
1410                 goto out_err_free;
1411 
1412         for_each_possible_cpu(cpu) {
1413                 pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
1414                 int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
1415                 int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
1416                 int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1417 
1418                 *pid = -1;
1419                 *depth = 0;
1420                 *ignore = 0;
1421                 *depth_irq = -1;
1422         }
1423 
1424         iter->private = data;
1425 
1426         return;
1427 
1428  out_err_free:
1429         kfree(data);
1430  out_err:
1431         pr_warn("function graph tracer: not enough memory\n");
1432 }
1433 
1434 void graph_trace_close(struct trace_iterator *iter)
1435 {
1436         struct fgraph_data *data = iter->private;
1437 
1438         if (data) {
1439                 free_percpu(data->cpu_data);
1440                 kfree(data);
1441         }
1442 }
1443 
1444 static int
1445 func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1446 {
1447         if (bit == TRACE_GRAPH_PRINT_IRQS)
1448                 ftrace_graph_skip_irqs = !set;
1449 
1450         if (bit == TRACE_GRAPH_SLEEP_TIME)
1451                 ftrace_graph_sleep_time_control(set);
1452 
1453         if (bit == TRACE_GRAPH_GRAPH_TIME)
1454                 ftrace_graph_graph_time_control(set);
1455 
1456         return 0;
1457 }
1458 
1459 static struct trace_event_functions graph_functions = {
1460         .trace          = print_graph_function_event,
1461 };
1462 
1463 static struct trace_event graph_trace_entry_event = {
1464         .type           = TRACE_GRAPH_ENT,
1465         .funcs          = &graph_functions,
1466 };
1467 
1468 static struct trace_event graph_trace_ret_event = {
1469         .type           = TRACE_GRAPH_RET,
1470         .funcs          = &graph_functions
1471 };
1472 
1473 static struct tracer graph_trace __tracer_data = {
1474         .name           = "function_graph",
1475         .update_thresh  = graph_trace_update_thresh,
1476         .open           = graph_trace_open,
1477         .pipe_open      = graph_trace_open,
1478         .close          = graph_trace_close,
1479         .pipe_close     = graph_trace_close,
1480         .init           = graph_trace_init,
1481         .reset          = graph_trace_reset,
1482         .print_line     = print_graph_function,
1483         .print_header   = print_graph_headers,
1484         .flags          = &tracer_flags,
1485         .set_flag       = func_graph_set_flag,
1486 #ifdef CONFIG_FTRACE_SELFTEST
1487         .selftest       = trace_selftest_startup_function_graph,
1488 #endif
1489 };
1490 
1491 
1492 static ssize_t
1493 graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt,
1494                   loff_t *ppos)
1495 {
1496         unsigned long val;
1497         int ret;
1498 
1499         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
1500         if (ret)
1501                 return ret;
1502 
1503         fgraph_max_depth = val;
1504 
1505         *ppos += cnt;
1506 
1507         return cnt;
1508 }
1509 
1510 static ssize_t
1511 graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt,
1512                  loff_t *ppos)
1513 {
1514         char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/
1515         int n;
1516 
1517         n = sprintf(buf, "%d\n", fgraph_max_depth);
1518 
1519         return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
1520 }
1521 
1522 static const struct file_operations graph_depth_fops = {
1523         .open           = tracing_open_generic,
1524         .write          = graph_depth_write,
1525         .read           = graph_depth_read,
1526         .llseek         = generic_file_llseek,
1527 };
1528 
1529 static __init int init_graph_tracefs(void)
1530 {
1531         struct dentry *d_tracer;
1532 
1533         d_tracer = tracing_init_dentry();
1534         if (IS_ERR(d_tracer))
1535                 return 0;
1536 
1537         trace_create_file("max_graph_depth", 0644, d_tracer,
1538                           NULL, &graph_depth_fops);
1539 
1540         return 0;
1541 }
1542 fs_initcall(init_graph_tracefs);
1543 
1544 static __init int init_graph_trace(void)
1545 {
1546         max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);
1547 
1548         if (!register_trace_event(&graph_trace_entry_event)) {
1549                 pr_warn("Warning: could not register graph trace events\n");
1550                 return 1;
1551         }
1552 
1553         if (!register_trace_event(&graph_trace_ret_event)) {
1554                 pr_warn("Warning: could not register graph trace events\n");
1555                 return 1;
1556         }
1557 
1558         return register_tracer(&graph_trace);
1559 }
1560 
1561 core_initcall(init_graph_trace);
1562 

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