kernel/trace/trace_functions_graph.c

   1 /*
   2  *
   3  * Function graph tracer.
   4  * Copyright (c) 2008 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/debugfs.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/ftrace.h>
  12 #include <linux/fs.h>
  13
  14 #include "trace.h"
  15 #include "trace_output.h"
  16
  17 #define TRACE_GRAPH_INDENT      2
  18
  19 /* Flag options */
  20 #define TRACE_GRAPH_PRINT_OVERRUN       0x1
  21 #define TRACE_GRAPH_PRINT_CPU           0x2
  22 #define TRACE_GRAPH_PRINT_OVERHEAD      0x4
  23 #define TRACE_GRAPH_PRINT_PROC          0x8
  24
  25 static struct tracer_opt trace_opts[] = {
  26         /* Display overruns ? */
  27         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
  28         /* Display CPU ? */
  29         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
  30         /* Display Overhead ? */
  31         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
  32         /* Display proc name/pid */
  33         { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
  34         { } /* Empty entry */
  35 };
  36
  37 static struct tracer_flags tracer_flags = {
  38         /* Don't display overruns and proc by default */
  39         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD,
  40         .opts = trace_opts
  41 };
  42
  43 /* pid on the last trace processed */
  44 static pid_t last_pid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
  45
  46 static int graph_trace_init(struct trace_array *tr)
  47 {
  48         int cpu, ret;
  49
  50         for_each_online_cpu(cpu)
  51                 tracing_reset(tr, cpu);
  52
  53         ret = register_ftrace_graph(&trace_graph_return,
  54                                         &trace_graph_entry);
  55         if (ret)
  56                 return ret;
  57         tracing_start_cmdline_record();
  58
  59         return 0;
  60 }
  61
  62 static void graph_trace_reset(struct trace_array *tr)
  63 {
  64         tracing_stop_cmdline_record();
  65         unregister_ftrace_graph();
  66 }
  67
  68 static inline int log10_cpu(int nb)
  69 {
  70         if (nb / 100)
  71                 return 3;
  72         if (nb / 10)
  73                 return 2;
  74         return 1;
  75 }
  76
  77 static enum print_line_t
  78 print_graph_cpu(struct trace_seq *s, int cpu)
  79 {
  80         int i;
  81         int ret;
  82         int log10_this = log10_cpu(cpu);
  83         int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));
  84
  85
  86         /*
  87          * Start with a space character - to make it stand out
  88          * to the right a bit when trace output is pasted into
  89          * email:
  90          */
  91         ret = trace_seq_printf(s, " ");
  92
  93         /*
  94          * Tricky - we space the CPU field according to the max
  95          * number of online CPUs. On a 2-cpu system it would take
  96          * a maximum of 1 digit - on a 128 cpu system it would
  97          * take up to 3 digits:
  98          */
  99         for (i = 0; i < log10_all - log10_this; i++) {
 100                 ret = trace_seq_printf(s, " ");
 101                 if (!ret)
 102                         return TRACE_TYPE_PARTIAL_LINE;
 103         }
 104         ret = trace_seq_printf(s, "%d) ", cpu);
 105         if (!ret)
 106                 return TRACE_TYPE_PARTIAL_LINE;
 107
 108         return TRACE_TYPE_HANDLED;
 109 }
 110
 111 #define TRACE_GRAPH_PROCINFO_LENGTH     14
 112
 113 static enum print_line_t
 114 print_graph_proc(struct trace_seq *s, pid_t pid)
 115 {
 116         int i;
 117         int ret;
 118         int len;
 119         char comm[8];
 120         int spaces = 0;
 121         /* sign + log10(MAX_INT) + '\0' */
 122         char pid_str[11];
 123
 124         strncpy(comm, trace_find_cmdline(pid), 7);
 125         comm[7] = '\0';
 126         sprintf(pid_str, "%d", pid);
 127
 128         /* 1 stands for the "-" character */
 129         len = strlen(comm) + strlen(pid_str) + 1;
 130
 131         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
 132                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
 133
 134         /* First spaces to align center */
 135         for (i = 0; i < spaces / 2; i++) {
 136                 ret = trace_seq_printf(s, " ");
 137                 if (!ret)
 138                         return TRACE_TYPE_PARTIAL_LINE;
 139         }
 140
 141         ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
 142         if (!ret)
 143                 return TRACE_TYPE_PARTIAL_LINE;
 144
 145         /* Last spaces to align center */
 146         for (i = 0; i < spaces - (spaces / 2); i++) {
 147                 ret = trace_seq_printf(s, " ");
 148                 if (!ret)
 149                         return TRACE_TYPE_PARTIAL_LINE;
 150         }
 151         return TRACE_TYPE_HANDLED;
 152 }
 153
 154
 155 /* If the pid changed since the last trace, output this event */
 156 static enum print_line_t
 157 verif_pid(struct trace_seq *s, pid_t pid, int cpu)
 158 {
 159         pid_t prev_pid;
 160         int ret;
 161
 162         if (last_pid[cpu] != -1 && last_pid[cpu] == pid)
 163                 return TRACE_TYPE_HANDLED;
 164
 165         prev_pid = last_pid[cpu];
 166         last_pid[cpu] = pid;
 167
 168 /*
 169  * Context-switch trace line:
 170
 171  ------------------------------------------
 172  | 1)  migration/0--1  =>  sshd-1755
 173  ------------------------------------------
 174
 175  */
 176         ret = trace_seq_printf(s,
 177                 " ------------------------------------------\n");
 178         if (!ret)
 179                 TRACE_TYPE_PARTIAL_LINE;
 180
 181         ret = print_graph_cpu(s, cpu);
 182         if (ret == TRACE_TYPE_PARTIAL_LINE)
 183                 TRACE_TYPE_PARTIAL_LINE;
 184
 185         ret = print_graph_proc(s, prev_pid);
 186         if (ret == TRACE_TYPE_PARTIAL_LINE)
 187                 TRACE_TYPE_PARTIAL_LINE;
 188
 189         ret = trace_seq_printf(s, " => ");
 190         if (!ret)
 191                 TRACE_TYPE_PARTIAL_LINE;
 192
 193         ret = print_graph_proc(s, pid);
 194         if (ret == TRACE_TYPE_PARTIAL_LINE)
 195                 TRACE_TYPE_PARTIAL_LINE;
 196
 197         ret = trace_seq_printf(s,
 198                 "\n ------------------------------------------\n\n");
 199         if (!ret)
 200                 TRACE_TYPE_PARTIAL_LINE;
 201
 202         return ret;
 203 }
 204
 205 static bool
 206 trace_branch_is_leaf(struct trace_iterator *iter,
 207                 struct ftrace_graph_ent_entry *curr)
 208 {
 209         struct ring_buffer_iter *ring_iter;
 210         struct ring_buffer_event *event;
 211         struct ftrace_graph_ret_entry *next;
 212
 213         ring_iter = iter->buffer_iter[iter->cpu];
 214
 215         if (!ring_iter)
 216                 return false;
 217
 218         event = ring_buffer_iter_peek(ring_iter, NULL);
 219
 220         if (!event)
 221                 return false;
 222
 223         next = ring_buffer_event_data(event);
 224
 225         if (next->ent.type != TRACE_GRAPH_RET)
 226                 return false;
 227
 228         if (curr->ent.pid != next->ent.pid ||
 229                         curr->graph_ent.func != next->ret.func)
 230                 return false;
 231
 232         return true;
 233 }
 234
 235 static enum print_line_t
 236 print_graph_irq(struct trace_seq *s, unsigned long addr,
 237                                 enum trace_type type, int cpu, pid_t pid)
 238 {
 239         int ret;
 240
 241         if (addr < (unsigned long)__irqentry_text_start ||
 242                 addr >= (unsigned long)__irqentry_text_end)
 243                 return TRACE_TYPE_UNHANDLED;
 244
 245         if (type == TRACE_GRAPH_ENT) {
 246                 ret = trace_seq_printf(s, "==========> |  ");
 247         } else {
 248                 /* Cpu */
 249                 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 250                         ret = print_graph_cpu(s, cpu);
 251                         if (ret == TRACE_TYPE_PARTIAL_LINE)
 252                                 return TRACE_TYPE_PARTIAL_LINE;
 253                 }
 254                 /* Proc */
 255                 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 256                         ret = print_graph_proc(s, pid);
 257                         if (ret == TRACE_TYPE_PARTIAL_LINE)
 258                                 return TRACE_TYPE_PARTIAL_LINE;
 259
 260                         ret = trace_seq_printf(s, " | ");
 261                         if (!ret)
 262                                 return TRACE_TYPE_PARTIAL_LINE;
 263                 }
 264
 265                 /* No overhead */
 266                 if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 267                         ret = trace_seq_printf(s, "  ");
 268                         if (!ret)
 269                                 return TRACE_TYPE_PARTIAL_LINE;
 270                 }
 271
 272                 ret = trace_seq_printf(s, "<========== |\n");
 273         }
 274         if (!ret)
 275                 return TRACE_TYPE_PARTIAL_LINE;
 276         return TRACE_TYPE_HANDLED;
 277 }
 278
 279 static enum print_line_t
 280 print_graph_duration(unsigned long long duration, struct trace_seq *s)
 281 {
 282         unsigned long nsecs_rem = do_div(duration, 1000);
 283         /* log10(ULONG_MAX) + '\0' */
 284         char msecs_str[21];
 285         char nsecs_str[5];
 286         int ret, len;
 287         int i;
 288
 289         sprintf(msecs_str, "%lu", (unsigned long) duration);
 290
 291         /* Print msecs */
 292         ret = trace_seq_printf(s, msecs_str);
 293         if (!ret)
 294                 return TRACE_TYPE_PARTIAL_LINE;
 295
 296         len = strlen(msecs_str);
 297
 298         /* Print nsecs (we don't want to exceed 7 numbers) */
 299         if (len < 7) {
 300                 snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
 301                 ret = trace_seq_printf(s, ".%s", nsecs_str);
 302                 if (!ret)
 303                         return TRACE_TYPE_PARTIAL_LINE;
 304                 len += strlen(nsecs_str);
 305         }
 306
 307         ret = trace_seq_printf(s, " us ");
 308         if (!ret)
 309                 return TRACE_TYPE_PARTIAL_LINE;
 310
 311         /* Print remaining spaces to fit the row's width */
 312         for (i = len; i < 7; i++) {
 313                 ret = trace_seq_printf(s, " ");
 314                 if (!ret)
 315                         return TRACE_TYPE_PARTIAL_LINE;
 316         }
 317
 318         ret = trace_seq_printf(s, "|  ");
 319         if (!ret)
 320                 return TRACE_TYPE_PARTIAL_LINE;
 321         return TRACE_TYPE_HANDLED;
 322
 323 }
 324
 325 /* Signal a overhead of time execution to the output */
 326 static int
 327 print_graph_overhead(unsigned long long duration, struct trace_seq *s)
 328 {
 329         /* Duration exceeded 100 msecs */
 330         if (duration > 100000ULL)
 331                 return trace_seq_printf(s, "! ");
 332
 333         /* Duration exceeded 10 msecs */
 334         if (duration > 10000ULL)
 335                 return trace_seq_printf(s, "+ ");
 336
 337         return trace_seq_printf(s, "  ");
 338 }
 339
 340 /* Case of a leaf function on its call entry */
 341 static enum print_line_t
 342 print_graph_entry_leaf(struct trace_iterator *iter,
 343                 struct ftrace_graph_ent_entry *entry, struct trace_seq *s)
 344 {
 345         struct ftrace_graph_ret_entry *ret_entry;
 346         struct ftrace_graph_ret *graph_ret;
 347         struct ring_buffer_event *event;
 348         struct ftrace_graph_ent *call;
 349         unsigned long long duration;
 350         int ret;
 351         int i;
 352
 353         event = ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
 354         ret_entry = ring_buffer_event_data(event);
 355         graph_ret = &ret_entry->ret;
 356         call = &entry->graph_ent;
 357         duration = graph_ret->rettime - graph_ret->calltime;
 358
 359         /* Overhead */
 360         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 361                 ret = print_graph_overhead(duration, s);
 362                 if (!ret)
 363                         return TRACE_TYPE_PARTIAL_LINE;
 364         }
 365
 366         /* Duration */
 367         ret = print_graph_duration(duration, s);
 368         if (ret == TRACE_TYPE_PARTIAL_LINE)
 369                 return TRACE_TYPE_PARTIAL_LINE;
 370
 371         /* Function */
 372         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 373                 ret = trace_seq_printf(s, " ");
 374                 if (!ret)
 375                         return TRACE_TYPE_PARTIAL_LINE;
 376         }
 377
 378         ret = seq_print_ip_sym(s, call->func, 0);
 379         if (!ret)
 380                 return TRACE_TYPE_PARTIAL_LINE;
 381
 382         ret = trace_seq_printf(s, "();\n");
 383         if (!ret)
 384                 return TRACE_TYPE_PARTIAL_LINE;
 385
 386         return TRACE_TYPE_HANDLED;
 387 }
 388
 389 static enum print_line_t
 390 print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
 391                         struct trace_seq *s, pid_t pid, int cpu)
 392 {
 393         int i;
 394         int ret;
 395         struct ftrace_graph_ent *call = &entry->graph_ent;
 396
 397         /* No overhead */
 398         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 399                 ret = trace_seq_printf(s, "  ");
 400                 if (!ret)
 401                         return TRACE_TYPE_PARTIAL_LINE;
 402         }
 403
 404         /* Interrupt */
 405         ret = print_graph_irq(s, call->func, TRACE_GRAPH_ENT, cpu, pid);
 406         if (ret == TRACE_TYPE_UNHANDLED) {
 407                 /* No time */
 408                 ret = trace_seq_printf(s, "            |  ");
 409                 if (!ret)
 410                         return TRACE_TYPE_PARTIAL_LINE;
 411         } else {
 412                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 413                         return TRACE_TYPE_PARTIAL_LINE;
 414         }
 415
 416
 417         /* Function */
 418         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 419                 ret = trace_seq_printf(s, " ");
 420                 if (!ret)
 421                         return TRACE_TYPE_PARTIAL_LINE;
 422         }
 423
 424         ret = seq_print_ip_sym(s, call->func, 0);
 425         if (!ret)
 426                 return TRACE_TYPE_PARTIAL_LINE;
 427
 428         ret = trace_seq_printf(s, "() {\n");
 429         if (!ret)
 430                 return TRACE_TYPE_PARTIAL_LINE;
 431
 432         return TRACE_TYPE_HANDLED;
 433 }
 434
 435 static enum print_line_t
 436 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
 437                         struct trace_iterator *iter, int cpu)
 438 {
 439         int ret;
 440         struct trace_entry *ent = iter->ent;
 441
 442         /* Pid */
 443         if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
 444                 return TRACE_TYPE_PARTIAL_LINE;
 445
 446         /* Cpu */
 447         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 448                 ret = print_graph_cpu(s, cpu);
 449                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 450                         return TRACE_TYPE_PARTIAL_LINE;
 451         }
 452
 453         /* Proc */
 454         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 455                 ret = print_graph_proc(s, ent->pid);
 456                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 457                         return TRACE_TYPE_PARTIAL_LINE;
 458
 459                 ret = trace_seq_printf(s, " | ");
 460                 if (!ret)
 461                         return TRACE_TYPE_PARTIAL_LINE;
 462         }
 463
 464         if (trace_branch_is_leaf(iter, field))
 465                 return print_graph_entry_leaf(iter, field, s);
 466         else
 467                 return print_graph_entry_nested(field, s, iter->ent->pid, cpu);
 468
 469 }
 470
 471 static enum print_line_t
 472 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 473                    struct trace_entry *ent, int cpu)
 474 {
 475         int i;
 476         int ret;
 477         unsigned long long duration = trace->rettime - trace->calltime;
 478
 479         /* Pid */
 480         if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
 481                 return TRACE_TYPE_PARTIAL_LINE;
 482
 483         /* Cpu */
 484         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 485                 ret = print_graph_cpu(s, cpu);
 486                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 487                         return TRACE_TYPE_PARTIAL_LINE;
 488         }
 489
 490         /* Proc */
 491         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 492                 ret = print_graph_proc(s, ent->pid);
 493                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 494                         return TRACE_TYPE_PARTIAL_LINE;
 495
 496                 ret = trace_seq_printf(s, " | ");
 497                 if (!ret)
 498                         return TRACE_TYPE_PARTIAL_LINE;
 499         }
 500
 501         /* Overhead */
 502         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 503                 ret = print_graph_overhead(duration, s);
 504                 if (!ret)
 505                         return TRACE_TYPE_PARTIAL_LINE;
 506         }
 507
 508         /* Duration */
 509         ret = print_graph_duration(duration, s);
 510         if (ret == TRACE_TYPE_PARTIAL_LINE)
 511                 return TRACE_TYPE_PARTIAL_LINE;
 512
 513         /* Closing brace */
 514         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
 515                 ret = trace_seq_printf(s, " ");
 516                 if (!ret)
 517                         return TRACE_TYPE_PARTIAL_LINE;
 518         }
 519
 520         ret = trace_seq_printf(s, "}\n");
 521         if (!ret)
 522                 return TRACE_TYPE_PARTIAL_LINE;
 523
 524         /* Overrun */
 525         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
 526                 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
 527                                         trace->overrun);
 528                 if (!ret)
 529                         return TRACE_TYPE_PARTIAL_LINE;
 530         }
 531
 532         ret = print_graph_irq(s, trace->func, TRACE_GRAPH_RET, cpu, ent->pid);
 533         if (ret == TRACE_TYPE_PARTIAL_LINE)
 534                 return TRACE_TYPE_PARTIAL_LINE;
 535
 536         return TRACE_TYPE_HANDLED;
 537 }
 538
 539 static enum print_line_t
 540 print_graph_comment(struct print_entry *trace, struct trace_seq *s,
 541                    struct trace_entry *ent, struct trace_iterator *iter)
 542 {
 543         int i;
 544         int ret;
 545
 546         /* Pid */
 547         if (verif_pid(s, ent->pid, iter->cpu) == TRACE_TYPE_PARTIAL_LINE)
 548                 return TRACE_TYPE_PARTIAL_LINE;
 549
 550         /* Cpu */
 551         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 552                 ret = print_graph_cpu(s, iter->cpu);
 553                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 554                         return TRACE_TYPE_PARTIAL_LINE;
 555         }
 556
 557         /* Proc */
 558         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 559                 ret = print_graph_proc(s, ent->pid);
 560                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 561                         return TRACE_TYPE_PARTIAL_LINE;
 562
 563                 ret = trace_seq_printf(s, " | ");
 564                 if (!ret)
 565                         return TRACE_TYPE_PARTIAL_LINE;
 566         }
 567
 568         /* No overhead */
 569         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 570                 ret = trace_seq_printf(s, "  ");
 571                 if (!ret)
 572                         return TRACE_TYPE_PARTIAL_LINE;
 573         }
 574
 575         /* No time */
 576         ret = trace_seq_printf(s, "            |  ");
 577         if (!ret)
 578                 return TRACE_TYPE_PARTIAL_LINE;
 579
 580         /* Indentation */
 581         if (trace->depth > 0)
 582                 for (i = 0; i < (trace->depth + 1) * TRACE_GRAPH_INDENT; i++) {
 583                         ret = trace_seq_printf(s, " ");
 584                         if (!ret)
 585                                 return TRACE_TYPE_PARTIAL_LINE;
 586                 }
 587
 588         /* The comment */
 589         ret = trace_seq_printf(s, "/* %s", trace->buf);
 590         if (!ret)
 591                 return TRACE_TYPE_PARTIAL_LINE;
 592
 593         /* Strip ending newline */
 594         if (s->buffer[s->len - 1] == '\n') {
 595                 s->buffer[s->len - 1] = '\0';
 596                 s->len--;
 597         }
 598
 599         ret = trace_seq_printf(s, " */\n");
 600         if (!ret)
 601                 return TRACE_TYPE_PARTIAL_LINE;
 602
 603         return TRACE_TYPE_HANDLED;
 604 }
 605
 606
 607 enum print_line_t
 608 print_graph_function(struct trace_iterator *iter)
 609 {
 610         struct trace_seq *s = &iter->seq;
 611         struct trace_entry *entry = iter->ent;
 612
 613         switch (entry->type) {
 614         case TRACE_GRAPH_ENT: {
 615                 struct ftrace_graph_ent_entry *field;
 616                 trace_assign_type(field, entry);
 617                 return print_graph_entry(field, s, iter,
 618                                          iter->cpu);
 619         }
 620         case TRACE_GRAPH_RET: {
 621                 struct ftrace_graph_ret_entry *field;
 622                 trace_assign_type(field, entry);
 623                 return print_graph_return(&field->ret, s, entry, iter->cpu);
 624         }
 625         case TRACE_PRINT: {
 626                 struct print_entry *field;
 627                 trace_assign_type(field, entry);
 628                 return print_graph_comment(field, s, entry, iter);
 629         }
 630         default:
 631                 return TRACE_TYPE_UNHANDLED;
 632         }
 633 }
 634
 635 static void print_graph_headers(struct seq_file *s)
 636 {
 637         /* 1st line */
 638         seq_printf(s, "# ");
 639         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 640                 seq_printf(s, "CPU ");
 641         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 642                 seq_printf(s, "TASK/PID     ");
 643         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD)
 644                 seq_printf(s, "OVERHEAD/");
 645         seq_printf(s, "DURATION            FUNCTION CALLS\n");
 646
 647         /* 2nd line */
 648         seq_printf(s, "# ");
 649         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 650                 seq_printf(s, "|   ");
 651         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 652                 seq_printf(s, "|      |     ");
 653         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 654                 seq_printf(s, "|        ");
 655                 seq_printf(s, "|                   |   |   |   |\n");
 656         } else
 657                 seq_printf(s, "    |               |   |   |   |\n");
 658 }
 659 static struct tracer graph_trace __read_mostly = {
 660         .name           = "function_graph",
 661         .init           = graph_trace_init,
 662         .reset          = graph_trace_reset,
 663         .print_line     = print_graph_function,
 664         .print_header   = print_graph_headers,
 665         .flags          = &tracer_flags,
 666 };
 667
 668 static __init int init_graph_trace(void)
 669 {
 670         return register_tracer(&graph_trace);
 671 }
 672
 673 device_initcall(init_graph_trace);