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
  16 #define TRACE_GRAPH_INDENT      2
  17
  18 /* Flag options */
  19 #define TRACE_GRAPH_PRINT_OVERRUN       0x1
  20 #define TRACE_GRAPH_PRINT_CPU           0x2
  21 #define TRACE_GRAPH_PRINT_OVERHEAD      0x4
  22 #define TRACE_GRAPH_PRINT_PROC          0x8
  23
  24 static struct tracer_opt trace_opts[] = {
  25         /* Display overruns ? */
  26         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
  27         /* Display CPU ? */
  28         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
  29         /* Display Overhead ? */
  30         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
  31         /* Display proc name/pid */
  32         { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
  33         { } /* Empty entry */
  34 };
  35
  36 static struct tracer_flags tracer_flags = {
  37         /* Don't display overruns and proc by default */
  38         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD,
  39         .opts = trace_opts
  40 };
  41
  42 /* pid on the last trace processed */
  43 static pid_t last_pid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
  44
  45 /* Add a function return address to the trace stack on thread info.*/
  46 int
  47 ftrace_push_return_trace(unsigned long ret, unsigned long long time,
  48                          unsigned long func, int *depth)
  49 {
  50         int index;
  51
  52         if (!current->ret_stack)
  53                 return -EBUSY;
  54
  55         /* The return trace stack is full */
  56         if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
  57                 atomic_inc(&current->trace_overrun);
  58                 return -EBUSY;
  59         }
  60
  61         index = ++current->curr_ret_stack;
  62         barrier();
  63         current->ret_stack[index].ret = ret;
  64         current->ret_stack[index].func = func;
  65         current->ret_stack[index].calltime = time;
  66         *depth = index;
  67
  68         return 0;
  69 }
  70
  71 /* Retrieve a function return address to the trace stack on thread info.*/
  72 void
  73 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
  74 {
  75         int index;
  76
  77         index = current->curr_ret_stack;
  78
  79         if (unlikely(index < 0)) {
  80                 ftrace_graph_stop();
  81                 WARN_ON(1);
  82                 /* Might as well panic, otherwise we have no where to go */
  83                 *ret = (unsigned long)panic;
  84                 return;
  85         }
  86
  87         *ret = current->ret_stack[index].ret;
  88         trace->func = current->ret_stack[index].func;
  89         trace->calltime = current->ret_stack[index].calltime;
  90         trace->overrun = atomic_read(&current->trace_overrun);
  91         trace->depth = index;
  92         barrier();
  93         current->curr_ret_stack--;
  94
  95 }
  96
  97 /*
  98  * Send the trace to the ring-buffer.
  99  * @return the original return address.
 100  */
 101 unsigned long ftrace_return_to_handler(void)
 102 {
 103         struct ftrace_graph_ret trace;
 104         unsigned long ret;
 105
 106         ftrace_pop_return_trace(&trace, &ret);
 107         trace.rettime = cpu_clock(raw_smp_processor_id());
 108         ftrace_graph_return(&trace);
 109
 110         if (unlikely(!ret)) {
 111                 ftrace_graph_stop();
 112                 WARN_ON(1);
 113                 /* Might as well panic. What else to do? */
 114                 ret = (unsigned long)panic;
 115         }
 116
 117         return ret;
 118 }
 119
 120 static int graph_trace_init(struct trace_array *tr)
 121 {
 122         int cpu, ret;
 123
 124         for_each_online_cpu(cpu)
 125                 tracing_reset(tr, cpu);
 126
 127         ret = register_ftrace_graph(&trace_graph_return,
 128                                         &trace_graph_entry);
 129         if (ret)
 130                 return ret;
 131         tracing_start_cmdline_record();
 132
 133         return 0;
 134 }
 135
 136 static void graph_trace_reset(struct trace_array *tr)
 137 {
 138         tracing_stop_cmdline_record();
 139         unregister_ftrace_graph();
 140 }
 141
 142 static inline int log10_cpu(int nb)
 143 {
 144         if (nb / 100)
 145                 return 3;
 146         if (nb / 10)
 147                 return 2;
 148         return 1;
 149 }
 150
 151 static enum print_line_t
 152 print_graph_cpu(struct trace_seq *s, int cpu)
 153 {
 154         int i;
 155         int ret;
 156         int log10_this = log10_cpu(cpu);
 157         int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));
 158
 159
 160         /*
 161          * Start with a space character - to make it stand out
 162          * to the right a bit when trace output is pasted into
 163          * email:
 164          */
 165         ret = trace_seq_printf(s, " ");
 166
 167         /*
 168          * Tricky - we space the CPU field according to the max
 169          * number of online CPUs. On a 2-cpu system it would take
 170          * a maximum of 1 digit - on a 128 cpu system it would
 171          * take up to 3 digits:
 172          */
 173         for (i = 0; i < log10_all - log10_this; i++) {
 174                 ret = trace_seq_printf(s, " ");
 175                 if (!ret)
 176                         return TRACE_TYPE_PARTIAL_LINE;
 177         }
 178         ret = trace_seq_printf(s, "%d) ", cpu);
 179         if (!ret)
 180                 return TRACE_TYPE_PARTIAL_LINE;
 181
 182         return TRACE_TYPE_HANDLED;
 183 }
 184
 185 #define TRACE_GRAPH_PROCINFO_LENGTH     14
 186
 187 static enum print_line_t
 188 print_graph_proc(struct trace_seq *s, pid_t pid)
 189 {
 190         int i;
 191         int ret;
 192         int len;
 193         char comm[8];
 194         int spaces = 0;
 195         /* sign + log10(MAX_INT) + '\0' */
 196         char pid_str[11];
 197
 198         strncpy(comm, trace_find_cmdline(pid), 7);
 199         comm[7] = '\0';
 200         sprintf(pid_str, "%d", pid);
 201
 202         /* 1 stands for the "-" character */
 203         len = strlen(comm) + strlen(pid_str) + 1;
 204
 205         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
 206                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
 207
 208         /* First spaces to align center */
 209         for (i = 0; i < spaces / 2; i++) {
 210                 ret = trace_seq_printf(s, " ");
 211                 if (!ret)
 212                         return TRACE_TYPE_PARTIAL_LINE;
 213         }
 214
 215         ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
 216         if (!ret)
 217                 return TRACE_TYPE_PARTIAL_LINE;
 218
 219         /* Last spaces to align center */
 220         for (i = 0; i < spaces - (spaces / 2); i++) {
 221                 ret = trace_seq_printf(s, " ");
 222                 if (!ret)
 223                         return TRACE_TYPE_PARTIAL_LINE;
 224         }
 225         return TRACE_TYPE_HANDLED;
 226 }
 227
 228
 229 /* If the pid changed since the last trace, output this event */
 230 static enum print_line_t
 231 verif_pid(struct trace_seq *s, pid_t pid, int cpu)
 232 {
 233         pid_t prev_pid;
 234         int ret;
 235
 236         if (last_pid[cpu] != -1 && last_pid[cpu] == pid)
 237                 return TRACE_TYPE_HANDLED;
 238
 239         prev_pid = last_pid[cpu];
 240         last_pid[cpu] = pid;
 241
 242 /*
 243  * Context-switch trace line:
 244
 245  ------------------------------------------
 246  | 1)  migration/0--1  =>  sshd-1755
 247  ------------------------------------------
 248
 249  */
 250         ret = trace_seq_printf(s,
 251                 " ------------------------------------------\n");
 252         if (!ret)
 253                 TRACE_TYPE_PARTIAL_LINE;
 254
 255         ret = print_graph_cpu(s, cpu);
 256         if (ret == TRACE_TYPE_PARTIAL_LINE)
 257                 TRACE_TYPE_PARTIAL_LINE;
 258
 259         ret = print_graph_proc(s, prev_pid);
 260         if (ret == TRACE_TYPE_PARTIAL_LINE)
 261                 TRACE_TYPE_PARTIAL_LINE;
 262
 263         ret = trace_seq_printf(s, " => ");
 264         if (!ret)
 265                 TRACE_TYPE_PARTIAL_LINE;
 266
 267         ret = print_graph_proc(s, pid);
 268         if (ret == TRACE_TYPE_PARTIAL_LINE)
 269                 TRACE_TYPE_PARTIAL_LINE;
 270
 271         ret = trace_seq_printf(s,
 272                 "\n ------------------------------------------\n\n");
 273         if (!ret)
 274                 TRACE_TYPE_PARTIAL_LINE;
 275
 276         return ret;
 277 }
 278
 279 static bool
 280 trace_branch_is_leaf(struct trace_iterator *iter,
 281                 struct ftrace_graph_ent_entry *curr)
 282 {
 283         struct ring_buffer_iter *ring_iter;
 284         struct ring_buffer_event *event;
 285         struct ftrace_graph_ret_entry *next;
 286
 287         ring_iter = iter->buffer_iter[iter->cpu];
 288
 289         if (!ring_iter)
 290                 return false;
 291
 292         event = ring_buffer_iter_peek(ring_iter, NULL);
 293
 294         if (!event)
 295                 return false;
 296
 297         next = ring_buffer_event_data(event);
 298
 299         if (next->ent.type != TRACE_GRAPH_RET)
 300                 return false;
 301
 302         if (curr->ent.pid != next->ent.pid ||
 303                         curr->graph_ent.func != next->ret.func)
 304                 return false;
 305
 306         return true;
 307 }
 308
 309 static enum print_line_t
 310 print_graph_irq(struct trace_seq *s, unsigned long addr,
 311                                 enum trace_type type, int cpu, pid_t pid)
 312 {
 313         int ret;
 314
 315         if (addr < (unsigned long)__irqentry_text_start ||
 316                 addr >= (unsigned long)__irqentry_text_end)
 317                 return TRACE_TYPE_UNHANDLED;
 318
 319         if (type == TRACE_GRAPH_ENT) {
 320                 ret = trace_seq_printf(s, "==========> |  ");
 321         } else {
 322                 /* Cpu */
 323                 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 324                         ret = print_graph_cpu(s, cpu);
 325                         if (ret == TRACE_TYPE_PARTIAL_LINE)
 326                                 return TRACE_TYPE_PARTIAL_LINE;
 327                 }
 328                 /* Proc */
 329                 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 330                         ret = print_graph_proc(s, pid);
 331                         if (ret == TRACE_TYPE_PARTIAL_LINE)
 332                                 return TRACE_TYPE_PARTIAL_LINE;
 333
 334                         ret = trace_seq_printf(s, " | ");
 335                         if (!ret)
 336                                 return TRACE_TYPE_PARTIAL_LINE;
 337                 }
 338
 339                 /* No overhead */
 340                 if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 341                         ret = trace_seq_printf(s, "  ");
 342                         if (!ret)
 343                                 return TRACE_TYPE_PARTIAL_LINE;
 344                 }
 345
 346                 ret = trace_seq_printf(s, "<========== |\n");
 347         }
 348         if (!ret)
 349                 return TRACE_TYPE_PARTIAL_LINE;
 350         return TRACE_TYPE_HANDLED;
 351 }
 352
 353 static enum print_line_t
 354 print_graph_duration(unsigned long long duration, struct trace_seq *s)
 355 {
 356         unsigned long nsecs_rem = do_div(duration, 1000);
 357         /* log10(ULONG_MAX) + '\0' */
 358         char msecs_str[21];
 359         char nsecs_str[5];
 360         int ret, len;
 361         int i;
 362
 363         sprintf(msecs_str, "%lu", (unsigned long) duration);
 364
 365         /* Print msecs */
 366         ret = trace_seq_printf(s, msecs_str);
 367         if (!ret)
 368                 return TRACE_TYPE_PARTIAL_LINE;
 369
 370         len = strlen(msecs_str);
 371
 372         /* Print nsecs (we don't want to exceed 7 numbers) */
 373         if (len < 7) {
 374                 snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
 375                 ret = trace_seq_printf(s, ".%s", nsecs_str);
 376                 if (!ret)
 377                         return TRACE_TYPE_PARTIAL_LINE;
 378                 len += strlen(nsecs_str);
 379         }
 380
 381         ret = trace_seq_printf(s, " us ");
 382         if (!ret)
 383                 return TRACE_TYPE_PARTIAL_LINE;
 384
 385         /* Print remaining spaces to fit the row's width */
 386         for (i = len; i < 7; i++) {
 387                 ret = trace_seq_printf(s, " ");
 388                 if (!ret)
 389                         return TRACE_TYPE_PARTIAL_LINE;
 390         }
 391
 392         ret = trace_seq_printf(s, "|  ");
 393         if (!ret)
 394                 return TRACE_TYPE_PARTIAL_LINE;
 395         return TRACE_TYPE_HANDLED;
 396
 397 }
 398
 399 /* Signal a overhead of time execution to the output */
 400 static int
 401 print_graph_overhead(unsigned long long duration, struct trace_seq *s)
 402 {
 403         /* Duration exceeded 100 msecs */
 404         if (duration > 100000ULL)
 405                 return trace_seq_printf(s, "! ");
 406
 407         /* Duration exceeded 10 msecs */
 408         if (duration > 10000ULL)
 409                 return trace_seq_printf(s, "+ ");
 410
 411         return trace_seq_printf(s, "  ");
 412 }
 413
 414 /* Case of a leaf function on its call entry */
 415 static enum print_line_t
 416 print_graph_entry_leaf(struct trace_iterator *iter,
 417                 struct ftrace_graph_ent_entry *entry, struct trace_seq *s)
 418 {
 419         struct ftrace_graph_ret_entry *ret_entry;
 420         struct ftrace_graph_ret *graph_ret;
 421         struct ring_buffer_event *event;
 422         struct ftrace_graph_ent *call;
 423         unsigned long long duration;
 424         int ret;
 425         int i;
 426
 427         event = ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
 428         ret_entry = ring_buffer_event_data(event);
 429         graph_ret = &ret_entry->ret;
 430         call = &entry->graph_ent;
 431         duration = graph_ret->rettime - graph_ret->calltime;
 432
 433         /* Overhead */
 434         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 435                 ret = print_graph_overhead(duration, s);
 436                 if (!ret)
 437                         return TRACE_TYPE_PARTIAL_LINE;
 438         }
 439
 440         /* Duration */
 441         ret = print_graph_duration(duration, s);
 442         if (ret == TRACE_TYPE_PARTIAL_LINE)
 443                 return TRACE_TYPE_PARTIAL_LINE;
 444
 445         /* Function */
 446         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 447                 ret = trace_seq_printf(s, " ");
 448                 if (!ret)
 449                         return TRACE_TYPE_PARTIAL_LINE;
 450         }
 451
 452         ret = seq_print_ip_sym(s, call->func, 0);
 453         if (!ret)
 454                 return TRACE_TYPE_PARTIAL_LINE;
 455
 456         ret = trace_seq_printf(s, "();\n");
 457         if (!ret)
 458                 return TRACE_TYPE_PARTIAL_LINE;
 459
 460         return TRACE_TYPE_HANDLED;
 461 }
 462
 463 static enum print_line_t
 464 print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
 465                         struct trace_seq *s, pid_t pid, int cpu)
 466 {
 467         int i;
 468         int ret;
 469         struct ftrace_graph_ent *call = &entry->graph_ent;
 470
 471         /* No overhead */
 472         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 473                 ret = trace_seq_printf(s, "  ");
 474                 if (!ret)
 475                         return TRACE_TYPE_PARTIAL_LINE;
 476         }
 477
 478         /* Interrupt */
 479         ret = print_graph_irq(s, call->func, TRACE_GRAPH_ENT, cpu, pid);
 480         if (ret == TRACE_TYPE_UNHANDLED) {
 481                 /* No time */
 482                 ret = trace_seq_printf(s, "            |  ");
 483                 if (!ret)
 484                         return TRACE_TYPE_PARTIAL_LINE;
 485         } else {
 486                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 487                         return TRACE_TYPE_PARTIAL_LINE;
 488         }
 489
 490
 491         /* Function */
 492         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 493                 ret = trace_seq_printf(s, " ");
 494                 if (!ret)
 495                         return TRACE_TYPE_PARTIAL_LINE;
 496         }
 497
 498         ret = seq_print_ip_sym(s, call->func, 0);
 499         if (!ret)
 500                 return TRACE_TYPE_PARTIAL_LINE;
 501
 502         ret = trace_seq_printf(s, "() {\n");
 503         if (!ret)
 504                 return TRACE_TYPE_PARTIAL_LINE;
 505
 506         return TRACE_TYPE_HANDLED;
 507 }
 508
 509 static enum print_line_t
 510 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
 511                         struct trace_iterator *iter, int cpu)
 512 {
 513         int ret;
 514         struct trace_entry *ent = iter->ent;
 515
 516         /* Pid */
 517         if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
 518                 return TRACE_TYPE_PARTIAL_LINE;
 519
 520         /* Cpu */
 521         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 522                 ret = print_graph_cpu(s, cpu);
 523                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 524                         return TRACE_TYPE_PARTIAL_LINE;
 525         }
 526
 527         /* Proc */
 528         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 529                 ret = print_graph_proc(s, ent->pid);
 530                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 531                         return TRACE_TYPE_PARTIAL_LINE;
 532
 533                 ret = trace_seq_printf(s, " | ");
 534                 if (!ret)
 535                         return TRACE_TYPE_PARTIAL_LINE;
 536         }
 537
 538         if (trace_branch_is_leaf(iter, field))
 539                 return print_graph_entry_leaf(iter, field, s);
 540         else
 541                 return print_graph_entry_nested(field, s, iter->ent->pid, cpu);
 542
 543 }
 544
 545 static enum print_line_t
 546 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 547                    struct trace_entry *ent, int cpu)
 548 {
 549         int i;
 550         int ret;
 551         unsigned long long duration = trace->rettime - trace->calltime;
 552
 553         /* Pid */
 554         if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
 555                 return TRACE_TYPE_PARTIAL_LINE;
 556
 557         /* Cpu */
 558         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 559                 ret = print_graph_cpu(s, cpu);
 560                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 561                         return TRACE_TYPE_PARTIAL_LINE;
 562         }
 563
 564         /* Proc */
 565         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 566                 ret = print_graph_proc(s, ent->pid);
 567                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 568                         return TRACE_TYPE_PARTIAL_LINE;
 569
 570                 ret = trace_seq_printf(s, " | ");
 571                 if (!ret)
 572                         return TRACE_TYPE_PARTIAL_LINE;
 573         }
 574
 575         /* Overhead */
 576         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 577                 ret = print_graph_overhead(duration, s);
 578                 if (!ret)
 579                         return TRACE_TYPE_PARTIAL_LINE;
 580         }
 581
 582         /* Duration */
 583         ret = print_graph_duration(duration, s);
 584         if (ret == TRACE_TYPE_PARTIAL_LINE)
 585                 return TRACE_TYPE_PARTIAL_LINE;
 586
 587         /* Closing brace */
 588         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
 589                 ret = trace_seq_printf(s, " ");
 590                 if (!ret)
 591                         return TRACE_TYPE_PARTIAL_LINE;
 592         }
 593
 594         ret = trace_seq_printf(s, "}\n");
 595         if (!ret)
 596                 return TRACE_TYPE_PARTIAL_LINE;
 597
 598         /* Overrun */
 599         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
 600                 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
 601                                         trace->overrun);
 602                 if (!ret)
 603                         return TRACE_TYPE_PARTIAL_LINE;
 604         }
 605
 606         ret = print_graph_irq(s, trace->func, TRACE_GRAPH_RET, cpu, ent->pid);
 607         if (ret == TRACE_TYPE_PARTIAL_LINE)
 608                 return TRACE_TYPE_PARTIAL_LINE;
 609
 610         return TRACE_TYPE_HANDLED;
 611 }
 612
 613 static enum print_line_t
 614 print_graph_comment(struct print_entry *trace, struct trace_seq *s,
 615                    struct trace_entry *ent, struct trace_iterator *iter)
 616 {
 617         int i;
 618         int ret;
 619
 620         /* Pid */
 621         if (verif_pid(s, ent->pid, iter->cpu) == TRACE_TYPE_PARTIAL_LINE)
 622                 return TRACE_TYPE_PARTIAL_LINE;
 623
 624         /* Cpu */
 625         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 626                 ret = print_graph_cpu(s, iter->cpu);
 627                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 628                         return TRACE_TYPE_PARTIAL_LINE;
 629         }
 630
 631         /* Proc */
 632         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 633                 ret = print_graph_proc(s, ent->pid);
 634                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 635                         return TRACE_TYPE_PARTIAL_LINE;
 636
 637                 ret = trace_seq_printf(s, " | ");
 638                 if (!ret)
 639                         return TRACE_TYPE_PARTIAL_LINE;
 640         }
 641
 642         /* No overhead */
 643         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 644                 ret = trace_seq_printf(s, "  ");
 645                 if (!ret)
 646                         return TRACE_TYPE_PARTIAL_LINE;
 647         }
 648
 649         /* No time */
 650         ret = trace_seq_printf(s, "            |  ");
 651         if (!ret)
 652                 return TRACE_TYPE_PARTIAL_LINE;
 653
 654         /* Indentation */
 655         if (trace->depth > 0)
 656                 for (i = 0; i < (trace->depth + 1) * TRACE_GRAPH_INDENT; i++) {
 657                         ret = trace_seq_printf(s, " ");
 658                         if (!ret)
 659                                 return TRACE_TYPE_PARTIAL_LINE;
 660                 }
 661
 662         /* The comment */
 663         ret = trace_seq_printf(s, "/* %s", trace->buf);
 664         if (!ret)
 665                 return TRACE_TYPE_PARTIAL_LINE;
 666
 667         if (ent->flags & TRACE_FLAG_CONT)
 668                 trace_seq_print_cont(s, iter);
 669
 670         ret = trace_seq_printf(s, " */\n");
 671         if (!ret)
 672                 return TRACE_TYPE_PARTIAL_LINE;
 673
 674         return TRACE_TYPE_HANDLED;
 675 }
 676
 677
 678 enum print_line_t
 679 print_graph_function(struct trace_iterator *iter)
 680 {
 681         struct trace_seq *s = &iter->seq;
 682         struct trace_entry *entry = iter->ent;
 683
 684         switch (entry->type) {
 685         case TRACE_GRAPH_ENT: {
 686                 struct ftrace_graph_ent_entry *field;
 687                 trace_assign_type(field, entry);
 688                 return print_graph_entry(field, s, iter,
 689                                          iter->cpu);
 690         }
 691         case TRACE_GRAPH_RET: {
 692                 struct ftrace_graph_ret_entry *field;
 693                 trace_assign_type(field, entry);
 694                 return print_graph_return(&field->ret, s, entry, iter->cpu);
 695         }
 696         case TRACE_PRINT: {
 697                 struct print_entry *field;
 698                 trace_assign_type(field, entry);
 699                 return print_graph_comment(field, s, entry, iter);
 700         }
 701         default:
 702                 return TRACE_TYPE_UNHANDLED;
 703         }
 704 }
 705
 706 static void print_graph_headers(struct seq_file *s)
 707 {
 708         /* 1st line */
 709         seq_printf(s, "# ");
 710         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 711                 seq_printf(s, "CPU ");
 712         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 713                 seq_printf(s, "TASK/PID     ");
 714         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD)
 715                 seq_printf(s, "OVERHEAD/");
 716         seq_printf(s, "DURATION            FUNCTION CALLS\n");
 717
 718         /* 2nd line */
 719         seq_printf(s, "# ");
 720         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 721                 seq_printf(s, "|   ");
 722         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 723                 seq_printf(s, "|      |     ");
 724         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 725                 seq_printf(s, "|        ");
 726                 seq_printf(s, "|                   |   |   |   |\n");
 727         } else
 728                 seq_printf(s, "    |               |   |   |   |\n");
 729 }
 730 static struct tracer graph_trace __read_mostly = {
 731         .name           = "function_graph",
 732         .init           = graph_trace_init,
 733         .reset          = graph_trace_reset,
 734         .print_line     = print_graph_function,
 735         .print_header   = print_graph_headers,
 736         .flags          = &tracer_flags,
 737 };
 738
 739 static __init int init_graph_trace(void)
 740 {
 741         return register_tracer(&graph_trace);
 742 }
 743
 744 device_initcall(init_graph_trace);