Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 78af97163147bf4d4fd3a7f5de85e2034fbd4c17 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Function graph tracer.
 * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
 * Mostly borrowed from function tracer which
 * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
 *
 */
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/fs.h>

#include "trace.h"
#include "trace_output.h"

/* When set, irq functions will be ignored */
static int ftrace_graph_skip_irqs;

struct fgraph_cpu_data {
	pid_t		last_pid;
	int		depth;
	int		depth_irq;
	int		ignore;
	unsigned long	enter_funcs[FTRACE_RETFUNC_DEPTH];
};

struct fgraph_data {
	struct fgraph_cpu_data __percpu *cpu_data;

	/* Place to preserve last processed entry. */
	struct ftrace_graph_ent_entry	ent;
	struct ftrace_graph_ret_entry	ret;
	int				failed;
	int				cpu;
};

#define TRACE_GRAPH_INDENT	2

unsigned int fgraph_max_depth;

static struct tracer_opt trace_opts[] = {
	/* Display overruns? (for self-debug purpose) */
	{ TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
	/* Display CPU ? */
	{ TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
	/* Display Overhead ? */
	{ TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
	/* Display proc name/pid */
	{ TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
	/* Display duration of execution */
	{ TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
	/* Display absolute time of an entry */
	{ TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
	/* Display interrupts */
	{ TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
	/* Display function name after trailing } */
	{ TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) },
	/* Include sleep time (scheduled out) between entry and return */
	{ TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },

#ifdef CONFIG_FUNCTION_PROFILER
	/* Include time within nested functions */
	{ TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) },
#endif

	{ } /* Empty entry */
};

static struct tracer_flags tracer_flags = {
	/* Don't display overruns, proc, or tail by default */
	.val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
	       TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS |
	       TRACE_GRAPH_SLEEP_TIME | TRACE_GRAPH_GRAPH_TIME,
	.opts = trace_opts
};

static struct trace_array *graph_array;

/*
 * DURATION column is being also used to display IRQ signs,
 * following values are used by print_graph_irq and others
 * to fill in space into DURATION column.
 */
enum {
	FLAGS_FILL_FULL  = 1 << TRACE_GRAPH_PRINT_FILL_SHIFT,
	FLAGS_FILL_START = 2 << TRACE_GRAPH_PRINT_FILL_SHIFT,
	FLAGS_FILL_END   = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT,
};

static void
print_graph_duration(struct trace_array *tr, unsigned long long duration,
		     struct trace_seq *s, u32 flags);

int __trace_graph_entry(struct trace_array *tr,
				struct ftrace_graph_ent *trace,
				unsigned long flags,
				int pc)
{
	struct trace_event_call *call = &event_funcgraph_entry;
	struct ring_buffer_event *event;
	struct ring_buffer *buffer = tr->trace_buffer.buffer;
	struct ftrace_graph_ent_entry *entry;

	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
					  sizeof(*entry), flags, pc);
	if (!event)
		return 0;
	entry	= ring_buffer_event_data(event);
	entry->graph_ent			= *trace;
	if (!call_filter_check_discard(call, entry, buffer, event))
		trace_buffer_unlock_commit_nostack(buffer, event);

	return 1;
}

static inline int ftrace_graph_ignore_irqs(void)
{
	if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
		return 0;

	return in_irq();
}

int trace_graph_entry(struct ftrace_graph_ent *trace)
{
	struct trace_array *tr = graph_array;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int ret;
	int cpu;
	int pc;

	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
		return 0;

	/*
	 * Do not trace a function if it's filtered by set_graph_notrace.
	 * Make the index of ret stack negative to indicate that it should
	 * ignore further functions.  But it needs its own ret stack entry
	 * to recover the original index in order to continue tracing after
	 * returning from the function.
	 */
	if (ftrace_graph_notrace_addr(trace->func)) {
		trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
		/*
		 * Need to return 1 to have the return called
		 * that will clear the NOTRACE bit.
		 */
		return 1;
	}

	if (!ftrace_trace_task(tr))
		return 0;

	if (ftrace_graph_ignore_func(trace))
		return 0;

	if (ftrace_graph_ignore_irqs())
		return 0;

	/*
	 * Stop here if tracing_threshold is set. We only write function return
	 * events to the ring buffer.
	 */
	if (tracing_thresh)
		return 1;

	local_irq_save(flags);
	cpu = raw_smp_processor_id();
	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
		ret = __trace_graph_entry(tr, trace, flags, pc);
	} else {
		ret = 0;
	}

	atomic_dec(&data->disabled);
	local_irq_restore(flags);

	return ret;
}

static void
__trace_graph_function(struct trace_array *tr,
		unsigned long ip, unsigned long flags, int pc)
{
	u64 time = trace_clock_local();
	struct ftrace_graph_ent ent = {
		.func  = ip,
		.depth = 0,
	};
	struct ftrace_graph_ret ret = {
		.func     = ip,
		.depth    = 0,
		.calltime = time,
		.rettime  = time,
	};

	__trace_graph_entry(tr, &ent, flags, pc);
	__trace_graph_return(tr, &ret, flags, pc);
}

void
trace_graph_function(struct trace_array *tr,
		unsigned long ip, unsigned long parent_ip,
		unsigned long flags, int pc)
{
	__trace_graph_function(tr, ip, flags, pc);
}

void __trace_graph_return(struct trace_array *tr,
				struct ftrace_graph_ret *trace,
				unsigned long flags,
				int pc)
{
	struct trace_event_call *call = &event_funcgraph_exit;
	struct ring_buffer_event *event;
	struct ring_buffer *buffer = tr->trace_buffer.buffer;
	struct ftrace_graph_ret_entry *entry;

	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
					  sizeof(*entry), flags, pc);
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
	entry->ret				= *trace;
	if (!call_filter_check_discard(call, entry, buffer, event))
		trace_buffer_unlock_commit_nostack(buffer, event);
}

void trace_graph_return(struct ftrace_graph_ret *trace)
{
	struct trace_array *tr = graph_array;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

	ftrace_graph_addr_finish(trace);

	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
		trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
		return;
	}

	local_irq_save(flags);
	cpu = raw_smp_processor_id();
	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
		__trace_graph_return(tr, trace, flags, pc);
	}
	atomic_dec(&data->disabled);
	local_irq_restore(flags);
}

void set_graph_array(struct trace_array *tr)
{
	graph_array = tr;

	/* Make graph_array visible before we start tracing */

	smp_mb();
}

static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
{
	ftrace_graph_addr_finish(trace);

	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
		trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
		return;
	}

	if (tracing_thresh &&
	    (trace->rettime - trace->calltime < tracing_thresh))
		return;
	else
		trace_graph_return(trace);
}

static struct fgraph_ops funcgraph_thresh_ops = {
	.entryfunc = &trace_graph_entry,
	.retfunc = &trace_graph_thresh_return,
};

static struct fgraph_ops funcgraph_ops = {
	.entryfunc = &trace_graph_entry,
	.retfunc = &trace_graph_return,
};

static int graph_trace_init(struct trace_array *tr)
{
	int ret;

	set_graph_array(tr);
	if (tracing_thresh)
		ret = register_ftrace_graph(&funcgraph_thresh_ops);
	else
		ret = register_ftrace_graph(&funcgraph_ops);
	if (ret)
		return ret;
	tracing_start_cmdline_record();

	return 0;
}

static void graph_trace_reset(struct trace_array *tr)
{
	tracing_stop_cmdline_record();
	if (tracing_thresh)
		unregister_ftrace_graph(&funcgraph_thresh_ops);
	else
		unregister_ftrace_graph(&funcgraph_ops);
}

static int graph_trace_update_thresh(struct trace_array *tr)
{
	graph_trace_reset(tr);
	return graph_trace_init(tr);
}

static int max_bytes_for_cpu;

static void print_graph_cpu(struct trace_seq *s, int cpu)
{
	/*
	 * Start with a space character - to make it stand out
	 * to the right a bit when trace output is pasted into
	 * email:
	 */
	trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
}

#define TRACE_GRAPH_PROCINFO_LENGTH	14

static void print_graph_proc(struct trace_seq *s, pid_t pid)
{
	char comm[TASK_COMM_LEN];
	/* sign + log10(MAX_INT) + '\0' */
	char pid_str[11];
	int spaces = 0;
	int len;
	int i;

	trace_find_cmdline(pid, comm);
	comm[7] = '\0';
	sprintf(pid_str, "%d", pid);

	/* 1 stands for the "-" character */
	len = strlen(comm) + strlen(pid_str) + 1;

	if (len < TRACE_GRAPH_PROCINFO_LENGTH)
		spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;

	/* First spaces to align center */
	for (i = 0; i < spaces / 2; i++)
		trace_seq_putc(s, ' ');

	trace_seq_printf(s, "%s-%s", comm, pid_str);

	/* Last spaces to align center */
	for (i = 0; i < spaces - (spaces / 2); i++)
		trace_seq_putc(s, ' ');
}


static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
{
	trace_seq_putc(s, ' ');
	trace_print_lat_fmt(s, entry);
	trace_seq_puts(s, " | ");
}

/* If the pid changed since the last trace, output this event */
static void
verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
{
	pid_t prev_pid;
	pid_t *last_pid;

	if (!data)
		return;

	last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);

	if (*last_pid == pid)
		return;

	prev_pid = *last_pid;
	*last_pid = pid;

	if (prev_pid == -1)
		return;
/*
 * Context-switch trace line:

 ------------------------------------------
 | 1)  migration/0--1  =>  sshd-1755
 ------------------------------------------

 */
	trace_seq_puts(s, " ------------------------------------------\n");
	print_graph_cpu(s, cpu);
	print_graph_proc(s, prev_pid);
	trace_seq_puts(s, " => ");
	print_graph_proc(s, pid);
	trace_seq_puts(s, "\n ------------------------------------------\n\n");
}

static struct ftrace_graph_ret_entry *
get_return_for_leaf(struct trace_iterator *iter,
		struct ftrace_graph_ent_entry *curr)
{
	struct fgraph_data *data = iter->private;
	struct ring_buffer_iter *ring_iter = NULL;
	struct ring_buffer_event *event;
	struct ftrace_graph_ret_entry *next;

	/*
	 * If the previous output failed to write to the seq buffer,
	 * then we just reuse the data from before.
	 */
	if (data && data->failed) {
		curr = &data->ent;
		next = &data->ret;
	} else {

		ring_iter = trace_buffer_iter(iter, iter->cpu);

		/* First peek to compare current entry and the next one */
		if (ring_iter)
			event = ring_buffer_iter_peek(ring_iter, NULL);
		else {
			/*
			 * We need to consume the current entry to see
			 * the next one.
			 */
			ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
					    NULL, NULL);
			event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
						 NULL, NULL);
		}

		if (!event)
			return NULL;

		next = ring_buffer_event_data(event);

		if (data) {
			/*
			 * Save current and next entries for later reference
			 * if the output fails.
			 */
			data->ent = *curr;
			/*
			 * If the next event is not a return type, then
			 * we only care about what type it is. Otherwise we can
			 * safely copy the entire event.
			 */
			if (next->ent.type == TRACE_GRAPH_RET)
				data->ret = *next;
			else
				data->ret.ent.type = next->ent.type;
		}
	}

	if (next->ent.type != TRACE_GRAPH_RET)
		return NULL;

	if (curr->ent.pid != next->ent.pid ||
			curr->graph_ent.func != next->ret.func)
		return NULL;

	/* this is a leaf, now advance the iterator */
	if (ring_iter)
		ring_buffer_read(ring_iter, NULL);

	return next;
}

static void print_graph_abs_time(u64 t, struct trace_seq *s)
{
	unsigned long usecs_rem;

	usecs_rem = do_div(t, NSEC_PER_SEC);
	usecs_rem /= 1000;

	trace_seq_printf(s, "%5lu.%06lu |  ",
			 (unsigned long)t, usecs_rem);
}

static void
print_graph_rel_time(struct trace_iterator *iter, struct trace_seq *s)
{
	unsigned long long usecs;

	usecs = iter->ts - iter->trace_buffer->time_start;
	do_div(usecs, NSEC_PER_USEC);

	trace_seq_printf(s, "%9llu us |  ", usecs);
}

static void
print_graph_irq(struct trace_iterator *iter, unsigned long addr,
		enum trace_type type, int cpu, pid_t pid, u32 flags)
{
	struct trace_array *tr = iter->tr;
	struct trace_seq *s = &iter->seq;
	struct trace_entry *ent = iter->ent;

	if (addr < (unsigned long)__irqentry_text_start ||
		addr >= (unsigned long)__irqentry_text_end)
		return;

	if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
		/* Absolute time */
		if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
			print_graph_abs_time(iter->ts, s);

		/* Relative time */
		if (flags & TRACE_GRAPH_PRINT_REL_TIME)
			print_graph_rel_time(iter, s);

		/* Cpu */
		if (flags & TRACE_GRAPH_PRINT_CPU)
			print_graph_cpu(s, cpu);

		/* Proc */
		if (flags & TRACE_GRAPH_PRINT_PROC) {
			print_graph_proc(s, pid);
			trace_seq_puts(s, " | ");
		}

		/* Latency format */
		if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
			print_graph_lat_fmt(s, ent);
	}

	/* No overhead */
	print_graph_duration(tr, 0, s, flags | FLAGS_FILL_START);

	if (type == TRACE_GRAPH_ENT)
		trace_seq_puts(s, "==========>");
	else
		trace_seq_puts(s, "<==========");

	print_graph_duration(tr, 0, s, flags | FLAGS_FILL_END);
	trace_seq_putc(s, '\n');
}

void
trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
{
	unsigned long nsecs_rem = do_div(duration, 1000);
	/* log10(ULONG_MAX) + '\0' */
	char usecs_str[21];
	char nsecs_str[5];
	int len;
	int i;

	sprintf(usecs_str, "%lu", (unsigned long) duration);

	/* Print msecs */
	trace_seq_printf(s, "%s", usecs_str);

	len = strlen(usecs_str);

	/* Print nsecs (we don't want to exceed 7 numbers) */
	if (len < 7) {
		size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);

		snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
		trace_seq_printf(s, ".%s", nsecs_str);
		len += strlen(nsecs_str) + 1;
	}

	trace_seq_puts(s, " us ");

	/* Print remaining spaces to fit the row's width */
	for (i = len; i < 8; i++)
		trace_seq_putc(s, ' ');
}

static void
print_graph_duration(struct trace_array *tr, unsigned long long duration,
		     struct trace_seq *s, u32 flags)
{
	if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
	    !(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
		return;

	/* No real adata, just filling the column with spaces */
	switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) {
	case FLAGS_FILL_FULL:
		trace_seq_puts(s, "              |  ");
		return;
	case FLAGS_FILL_START:
		trace_seq_puts(s, "  ");
		return;
	case FLAGS_FILL_END:
		trace_seq_puts(s, " |");
		return;
	}

	/* Signal a overhead of time execution to the output */
	if (flags & TRACE_GRAPH_PRINT_OVERHEAD)
		trace_seq_printf(s, "%c ", trace_find_mark(duration));
	else
		trace_seq_puts(s, "  ");

	trace_print_graph_duration(duration, s);
	trace_seq_puts(s, "|  ");
}

/* Case of a leaf function on its call entry */
static enum print_line_t
print_graph_entry_leaf(struct trace_iterator *iter,
		struct ftrace_graph_ent_entry *entry,
		struct ftrace_graph_ret_entry *ret_entry,
		struct trace_seq *s, u32 flags)
{
	struct fgraph_data *data = iter->private;
	struct trace_array *tr = iter->tr;
	struct ftrace_graph_ret *graph_ret;
	struct ftrace_graph_ent *call;
	unsigned long long duration;
	int cpu = iter->cpu;
	int i;

	graph_ret = &ret_entry->ret;
	call = &entry->graph_ent;
	duration = graph_ret->rettime - graph_ret->calltime;

	if (data) {
		struct fgraph_cpu_data *cpu_data;

		cpu_data = per_cpu_ptr(data->cpu_data, cpu);

		/*
		 * Comments display at + 1 to depth. Since
		 * this is a leaf function, keep the comments
		 * equal to this depth.
		 */
		cpu_data->depth = call->depth - 1;

		/* No need to keep this function around for this depth */
		if (call->depth < FTRACE_RETFUNC_DEPTH &&
		    !WARN_ON_ONCE(call->depth < 0))
			cpu_data->enter_funcs[call->depth] = 0;
	}

	/* Overhead and duration */
	print_graph_duration(tr, duration, s, flags);

	/* Function */
	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
		trace_seq_putc(s, ' ');

	trace_seq_printf(s, "%ps();\n", (void *)call->func);

	print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET,
			cpu, iter->ent->pid, flags);

	return trace_handle_return(s);
}

static enum print_line_t
print_graph_entry_nested(struct trace_iterator *iter,
			 struct ftrace_graph_ent_entry *entry,
			 struct trace_seq *s, int cpu, u32 flags)
{
	struct ftrace_graph_ent *call = &entry->graph_ent;
	struct fgraph_data *data = iter->private;
	struct trace_array *tr = iter->tr;
	int i;

	if (data) {
		struct fgraph_cpu_data *cpu_data;
		int cpu = iter->cpu;

		cpu_data = per_cpu_ptr(data->cpu_data, cpu);
		cpu_data->depth = call->depth;

		/* Save this function pointer to see if the exit matches */
		if (call->depth < FTRACE_RETFUNC_DEPTH &&
		    !WARN_ON_ONCE(call->depth < 0))
			cpu_data->enter_funcs[call->depth] = call->func;
	}

	/* No time */
	print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);

	/* Function */
	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
		trace_seq_putc(s, ' ');

	trace_seq_printf(s, "%ps() {\n", (void *)call->func);

	if (trace_seq_has_overflowed(s))
		return TRACE_TYPE_PARTIAL_LINE;

	/*
	 * we already consumed the current entry to check the next one
	 * and see if this is a leaf.
	 */
	return TRACE_TYPE_NO_CONSUME;
}

static void
print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
		     int type, unsigned long addr, u32 flags)
{
	struct fgraph_data *data = iter->private;
	struct trace_entry *ent = iter->ent;
	struct trace_array *tr = iter->tr;
	int cpu = iter->cpu;

	/* Pid */
	verif_pid(s, ent->pid, cpu, data);

	if (type)
		/* Interrupt */
		print_graph_irq(iter, addr, type, cpu, ent->pid, flags);

	if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
		return;

	/* Absolute time */
	if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
		print_graph_abs_time(iter->ts, s);

	/* Relative time */
	if (flags & TRACE_GRAPH_PRINT_REL_TIME)
		print_graph_rel_time(iter, s);

	/* Cpu */
	if (flags & TRACE_GRAPH_PRINT_CPU)
		print_graph_cpu(s, cpu);

	/* Proc */
	if (flags & TRACE_GRAPH_PRINT_PROC) {
		print_graph_proc(s, ent->pid);
		trace_seq_puts(s, " | ");
	}

	/* Latency format */
	if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
		print_graph_lat_fmt(s, ent);

	return;
}

/*
 * Entry check for irq code
 *
 * returns 1 if
 *  - we are inside irq code
 *  - we just entered irq code
 *
 * retunns 0 if
 *  - funcgraph-interrupts option is set
 *  - we are not inside irq code
 */
static int
check_irq_entry(struct trace_iterator *iter, u32 flags,
		unsigned long addr, int depth)
{
	int cpu = iter->cpu;
	int *depth_irq;
	struct fgraph_data *data = iter->private;

	/*
	 * If we are either displaying irqs, or we got called as
	 * a graph event and private data does not exist,
	 * then we bypass the irq check.
	 */
	if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
	    (!data))
		return 0;

	depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);

	/*
	 * We are inside the irq code
	 */
	if (*depth_irq >= 0)
		return 1;

	if ((addr < (unsigned long)__irqentry_text_start) ||
	    (addr >= (unsigned long)__irqentry_text_end))
		return 0;

	/*
	 * We are entering irq code.
	 */
	*depth_irq = depth;
	return 1;
}

/*
 * Return check for irq code
 *
 * returns 1 if
 *  - we are inside irq code
 *  - we just left irq code
 *
 * returns 0 if
 *  - funcgraph-interrupts option is set
 *  - we are not inside irq code
 */
static int
check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
{
	int cpu = iter->cpu;
	int *depth_irq;
	struct fgraph_data *data = iter->private;

	/*
	 * If we are either displaying irqs, or we got called as
	 * a graph event and private data does not exist,
	 * then we bypass the irq check.
	 */
	if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
	    (!data))
		return 0;

	depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);

	/*
	 * We are not inside the irq code.
	 */
	if (*depth_irq == -1)
		return 0;

	/*
	 * We are inside the irq code, and this is returning entry.
	 * Let's not trace it and clear the entry depth, since
	 * we are out of irq code.
	 *
	 * This condition ensures that we 'leave the irq code' once
	 * we are out of the entry depth. Thus protecting us from
	 * the RETURN entry loss.
	 */
	if (*depth_irq >= depth) {
		*depth_irq = -1;
		return 1;
	}

	/*
	 * We are inside the irq code, and this is not the entry.
	 */
	return 1;
}

static enum print_line_t
print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
			struct trace_iterator *iter, u32 flags)
{
	struct fgraph_data *data = iter->private;
	struct ftrace_graph_ent *call = &field->graph_ent;
	struct ftrace_graph_ret_entry *leaf_ret;
	static enum print_line_t ret;
	int cpu = iter->cpu;

	if (check_irq_entry(iter, flags, call->func, call->depth))
		return TRACE_TYPE_HANDLED;

	print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags);

	leaf_ret = get_return_for_leaf(iter, field);
	if (leaf_ret)
		ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
	else
		ret = print_graph_entry_nested(iter, field, s, cpu, flags);

	if (data) {
		/*
		 * If we failed to write our output, then we need to make
		 * note of it. Because we already consumed our entry.
		 */
		if (s->full) {
			data->failed = 1;
			data->cpu = cpu;
		} else
			data->failed = 0;
	}

	return ret;
}

static enum print_line_t
print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
		   struct trace_entry *ent, struct trace_iterator *iter,
		   u32 flags)
{
	unsigned long long duration = trace->rettime - trace->calltime;
	struct fgraph_data *data = iter->private;
	struct trace_array *tr = iter->tr;
	pid_t pid = ent->pid;
	int cpu = iter->cpu;
	int func_match = 1;
	int i;

	if (check_irq_return(iter, flags, trace->depth))
		return TRACE_TYPE_HANDLED;

	if (data) {
		struct fgraph_cpu_data *cpu_data;
		int cpu = iter->cpu;

		cpu_data = per_cpu_ptr(data->cpu_data, cpu);

		/*
		 * Comments display at + 1 to depth. This is the
		 * return from a function, we now want the comments
		 * to display at the same level of the bracket.
		 */
		cpu_data->depth = trace->depth - 1;

		if (trace->depth < FTRACE_RETFUNC_DEPTH &&
		    !WARN_ON_ONCE(trace->depth < 0)) {
			if (cpu_data->enter_funcs[trace->depth] != trace->func)
				func_match = 0;
			cpu_data->enter_funcs[trace->depth] = 0;
		}
	}

	print_graph_prologue(iter, s, 0, 0, flags);

	/* Overhead and duration */
	print_graph_duration(tr, duration, s, flags);

	/* Closing brace */
	for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
		trace_seq_putc(s, ' ');

	/*
	 * If the return function does not have a matching entry,
	 * then the entry was lost. Instead of just printing
	 * the '}' and letting the user guess what function this
	 * belongs to, write out the function name. Always do
	 * that if the funcgraph-tail option is enabled.
	 */
	if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
		trace_seq_puts(s, "}\n");
	else
		trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);

	/* Overrun */
	if (flags & TRACE_GRAPH_PRINT_OVERRUN)
		trace_seq_printf(s, " (Overruns: %lu)\n",
				 trace->overrun);

	print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
			cpu, pid, flags);

	return trace_handle_return(s);
}

static enum print_line_t
print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
		    struct trace_iterator *iter, u32 flags)
{
	struct trace_array *tr = iter->tr;
	unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK);
	struct fgraph_data *data = iter->private;
	struct trace_event *event;
	int depth = 0;
	int ret;
	int i;

	if (data)
		depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;

	print_graph_prologue(iter, s, 0, 0, flags);

	/* No time */
	print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);

	/* Indentation */
	if (depth > 0)
		for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++)
			trace_seq_putc(s, ' ');

	/* The comment */
	trace_seq_puts(s, "/* ");

	switch (iter->ent->type) {
	case TRACE_BPUTS:
		ret = trace_print_bputs_msg_only(iter);
		if (ret != TRACE_TYPE_HANDLED)
			return ret;
		break;
	case TRACE_BPRINT:
		ret = trace_print_bprintk_msg_only(iter);
		if (ret != TRACE_TYPE_HANDLED)
			return ret;
		break;
	case TRACE_PRINT:
		ret = trace_print_printk_msg_only(iter);
		if (ret != TRACE_TYPE_HANDLED)
			return ret;
		break;
	default:
		event = ftrace_find_event(ent->type);
		if (!event)
			return TRACE_TYPE_UNHANDLED;

		ret = event->funcs->trace(iter, sym_flags, event);
		if (ret != TRACE_TYPE_HANDLED)
			return ret;
	}

	if (trace_seq_has_overflowed(s))
		goto out;

	/* Strip ending newline */
	if (s->buffer[s->seq.len - 1] == '\n') {
		s->buffer[s->seq.len - 1] = '\0';
		s->seq.len--;
	}

	trace_seq_puts(s, " */\n");
 out:
	return trace_handle_return(s);
}


enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags)
{
	struct ftrace_graph_ent_entry *field;
	struct fgraph_data *data = iter->private;
	struct trace_entry *entry = iter->ent;
	struct trace_seq *s = &iter->seq;
	int cpu = iter->cpu;
	int ret;

	if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
		per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
		return TRACE_TYPE_HANDLED;
	}

	/*
	 * If the last output failed, there's a possibility we need
	 * to print out the missing entry which would never go out.
	 */
	if (data && data->failed) {
		field = &data->ent;
		iter->cpu = data->cpu;
		ret = print_graph_entry(field, s, iter, flags);
		if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
			per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
			ret = TRACE_TYPE_NO_CONSUME;
		}
		iter->cpu = cpu;
		return ret;
	}

	switch (entry->type) {
	case TRACE_GRAPH_ENT: {
		/*
		 * print_graph_entry() may consume the current event,
		 * thus @field may become invalid, so we need to save it.
		 * sizeof(struct ftrace_graph_ent_entry) is very small,
		 * it can be safely saved at the stack.
		 */
		struct ftrace_graph_ent_entry saved;
		trace_assign_type(field, entry);
		saved = *field;
		return print_graph_entry(&saved, s, iter, flags);
	}
	case TRACE_GRAPH_RET: {
		struct ftrace_graph_ret_entry *field;
		trace_assign_type(field, entry);
		return print_graph_return(&field->ret, s, entry, iter, flags);
	}
	case TRACE_STACK:
	case TRACE_FN:
		/* dont trace stack and functions as comments */
		return TRACE_TYPE_UNHANDLED;

	default:
		return print_graph_comment(s, entry, iter, flags);
	}

	return TRACE_TYPE_HANDLED;
}

static enum print_line_t
print_graph_function(struct trace_iterator *iter)
{
	return print_graph_function_flags(iter, tracer_flags.val);
}

static enum print_line_t
print_graph_function_event(struct trace_iterator *iter, int flags,
			   struct trace_event *event)
{
	return print_graph_function(iter);
}

static void print_lat_header(struct seq_file *s, u32 flags)
{
	static const char spaces[] = "                "	/* 16 spaces */
		"    "					/* 4 spaces */
		"                 ";			/* 17 spaces */
	int size = 0;

	if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
		size += 16;
	if (flags & TRACE_GRAPH_PRINT_REL_TIME)
		size += 16;
	if (flags & TRACE_GRAPH_PRINT_CPU)
		size += 4;
	if (flags & TRACE_GRAPH_PRINT_PROC)
		size += 17;

	seq_printf(s, "#%.*s  _-----=> irqs-off        \n", size, spaces);
	seq_printf(s, "#%.*s / _----=> need-resched    \n", size, spaces);
	seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
	seq_printf(s, "#%.*s|| / _--=> preempt-depth   \n", size, spaces);
	seq_printf(s, "#%.*s||| /                      \n", size, spaces);
}

static void __print_graph_headers_flags(struct trace_array *tr,
					struct seq_file *s, u32 flags)
{
	int lat = tr->trace_flags & TRACE_ITER_LATENCY_FMT;

	if (lat)
		print_lat_header(s, flags);

	/* 1st line */
	seq_putc(s, '#');
	if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
		seq_puts(s, "     TIME       ");
	if (flags & TRACE_GRAPH_PRINT_REL_TIME)
		seq_puts(s, "   REL TIME     ");
	if (flags & TRACE_GRAPH_PRINT_CPU)
		seq_puts(s, " CPU");
	if (flags & TRACE_GRAPH_PRINT_PROC)
		seq_puts(s, "  TASK/PID       ");
	if (lat)
		seq_puts(s, "||||   ");
	if (flags & TRACE_GRAPH_PRINT_DURATION)
		seq_puts(s, "  DURATION   ");
	seq_puts(s, "               FUNCTION CALLS\n");

	/* 2nd line */
	seq_putc(s, '#');
	if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
		seq_puts(s, "      |         ");
	if (flags & TRACE_GRAPH_PRINT_REL_TIME)
		seq_puts(s, "      |         ");
	if (flags & TRACE_GRAPH_PRINT_CPU)
		seq_puts(s, " |  ");
	if (flags & TRACE_GRAPH_PRINT_PROC)
		seq_puts(s, "   |    |        ");
	if (lat)
		seq_puts(s, "||||   ");
	if (flags & TRACE_GRAPH_PRINT_DURATION)
		seq_puts(s, "   |   |      ");
	seq_puts(s, "               |   |   |   |\n");
}

static void print_graph_headers(struct seq_file *s)
{
	print_graph_headers_flags(s, tracer_flags.val);
}

void print_graph_headers_flags(struct seq_file *s, u32 flags)
{
	struct trace_iterator *iter = s->private;
	struct trace_array *tr = iter->tr;

	if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
		return;

	if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) {
		/* print nothing if the buffers are empty */
		if (trace_empty(iter))
			return;

		print_trace_header(s, iter);
	}

	__print_graph_headers_flags(tr, s, flags);
}

void graph_trace_open(struct trace_iterator *iter)
{
	/* pid and depth on the last trace processed */
	struct fgraph_data *data;
	gfp_t gfpflags;
	int cpu;

	iter->private = NULL;

	/* We can be called in atomic context via ftrace_dump() */
	gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;

	data = kzalloc(sizeof(*data), gfpflags);
	if (!data)
		goto out_err;

	data->cpu_data = alloc_percpu_gfp(struct fgraph_cpu_data, gfpflags);
	if (!data->cpu_data)
		goto out_err_free;

	for_each_possible_cpu(cpu) {
		pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
		int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
		int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
		int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);

		*pid = -1;
		*depth = 0;
		*ignore = 0;
		*depth_irq = -1;
	}

	iter->private = data;

	return;

 out_err_free:
	kfree(data);
 out_err:
	pr_warn("function graph tracer: not enough memory\n");
}

void graph_trace_close(struct trace_iterator *iter)
{
	struct fgraph_data *data = iter->private;

	if (data) {
		free_percpu(data->cpu_data);
		kfree(data);
	}
}

static int
func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
{
	if (bit == TRACE_GRAPH_PRINT_IRQS)
		ftrace_graph_skip_irqs = !set;

	if (bit == TRACE_GRAPH_SLEEP_TIME)
		ftrace_graph_sleep_time_control(set);

	if (bit == TRACE_GRAPH_GRAPH_TIME)
		ftrace_graph_graph_time_control(set);

	return 0;
}

static struct trace_event_functions graph_functions = {
	.trace		= print_graph_function_event,
};

static struct trace_event graph_trace_entry_event = {
	.type		= TRACE_GRAPH_ENT,
	.funcs		= &graph_functions,
};

static struct trace_event graph_trace_ret_event = {
	.type		= TRACE_GRAPH_RET,
	.funcs		= &graph_functions
};

static struct tracer graph_trace __tracer_data = {
	.name		= "function_graph",
	.update_thresh	= graph_trace_update_thresh,
	.open		= graph_trace_open,
	.pipe_open	= graph_trace_open,
	.close		= graph_trace_close,
	.pipe_close	= graph_trace_close,
	.init		= graph_trace_init,
	.reset		= graph_trace_reset,
	.print_line	= print_graph_function,
	.print_header	= print_graph_headers,
	.flags		= &tracer_flags,
	.set_flag	= func_graph_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
	.selftest	= trace_selftest_startup_function_graph,
#endif
};


static ssize_t
graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt,
		  loff_t *ppos)
{
	unsigned long val;
	int ret;

	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
	if (ret)
		return ret;

	fgraph_max_depth = val;

	*ppos += cnt;

	return cnt;
}

static ssize_t
graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt,
		 loff_t *ppos)
{
	char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/
	int n;

	n = sprintf(buf, "%d\n", fgraph_max_depth);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
}

static const struct file_operations graph_depth_fops = {
	.open		= tracing_open_generic,
	.write		= graph_depth_write,
	.read		= graph_depth_read,
	.llseek		= generic_file_llseek,
};

static __init int init_graph_tracefs(void)
{
	struct dentry *d_tracer;

	d_tracer = tracing_init_dentry();
	if (IS_ERR(d_tracer))
		return 0;

	trace_create_file("max_graph_depth", 0644, d_tracer,
			  NULL, &graph_depth_fops);

	return 0;
}
fs_initcall(init_graph_tracefs);

static __init int init_graph_trace(void)
{
	max_bytes_for_cpu = snprintf(NULL, 0, "%u", nr_cpu_ids - 1);

	if (!register_trace_event(&graph_trace_entry_event)) {
		pr_warn("Warning: could not register graph trace events\n");
		return 1;
	}

	if (!register_trace_event(&graph_trace_ret_event)) {
		pr_warn("Warning: could not register graph trace events\n");
		return 1;
	}

	return register_tracer(&graph_trace);
}

core_initcall(init_graph_trace);