git.oblomov.eu Git - linux-2.6/blob - kernel/trace/trace_functions_graph.c

   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/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 struct fgraph_data {
  18         pid_t           last_pid;
  19         int             depth;
  20 };
  21
  22 #define TRACE_GRAPH_INDENT      2
  23
  24 /* Flag options */
  25 #define TRACE_GRAPH_PRINT_OVERRUN       0x1
  26 #define TRACE_GRAPH_PRINT_CPU           0x2
  27 #define TRACE_GRAPH_PRINT_OVERHEAD      0x4
  28 #define TRACE_GRAPH_PRINT_PROC          0x8
  29 #define TRACE_GRAPH_PRINT_DURATION      0x10
  30 #define TRACE_GRAPH_PRINT_ABS_TIME      0X20
  31
  32 static struct tracer_opt trace_opts[] = {
  33         /* Display overruns? (for self-debug purpose) */
  34         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
  35         /* Display CPU ? */
  36         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
  37         /* Display Overhead ? */
  38         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
  39         /* Display proc name/pid */
  40         { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
  41         /* Display duration of execution */
  42         { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
  43         /* Display absolute time of an entry */
  44         { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
  45         { } /* Empty entry */
  46 };
  47
  48 static struct tracer_flags tracer_flags = {
  49         /* Don't display overruns and proc by default */
  50         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
  51                TRACE_GRAPH_PRINT_DURATION,
  52         .opts = trace_opts
  53 };
  54
  55 /* pid on the last trace processed */
  56
  57
  58 /* Add a function return address to the trace stack on thread info.*/
  59 int
  60 ftrace_push_return_trace(unsigned long ret, unsigned long long time,
  61                          unsigned long func, int *depth)
  62 {
  63         int index;
  64
  65         if (!current->ret_stack)
  66                 return -EBUSY;
  67
  68         /* The return trace stack is full */
  69         if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
  70                 atomic_inc(&current->trace_overrun);
  71                 return -EBUSY;
  72         }
  73
  74         index = ++current->curr_ret_stack;
  75         barrier();
  76         current->ret_stack[index].ret = ret;
  77         current->ret_stack[index].func = func;
  78         current->ret_stack[index].calltime = time;
  79         *depth = index;
  80
  81         return 0;
  82 }
  83
  84 /* Retrieve a function return address to the trace stack on thread info.*/
  85 void
  86 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
  87 {
  88         int index;
  89
  90         index = current->curr_ret_stack;
  91
  92         if (unlikely(index < 0)) {
  93                 ftrace_graph_stop();
  94                 WARN_ON(1);
  95                 /* Might as well panic, otherwise we have no where to go */
  96                 *ret = (unsigned long)panic;
  97                 return;
  98         }
  99
 100         *ret = current->ret_stack[index].ret;
 101         trace->func = current->ret_stack[index].func;
 102         trace->calltime = current->ret_stack[index].calltime;
 103         trace->overrun = atomic_read(&current->trace_overrun);
 104         trace->depth = index;
 105         barrier();
 106         current->curr_ret_stack--;
 107
 108 }
 109
 110 /*
 111  * Send the trace to the ring-buffer.
 112  * @return the original return address.
 113  */
 114 unsigned long ftrace_return_to_handler(void)
 115 {
 116         struct ftrace_graph_ret trace;
 117         unsigned long ret;
 118
 119         ftrace_pop_return_trace(&trace, &ret);
 120         trace.rettime = trace_clock_local();
 121         ftrace_graph_return(&trace);
 122
 123         if (unlikely(!ret)) {
 124                 ftrace_graph_stop();
 125                 WARN_ON(1);
 126                 /* Might as well panic. What else to do? */
 127                 ret = (unsigned long)panic;
 128         }
 129
 130         return ret;
 131 }
 132
 133 static int graph_trace_init(struct trace_array *tr)
 134 {
 135         int ret = register_ftrace_graph(&trace_graph_return,
 136                                         &trace_graph_entry);
 137         if (ret)
 138                 return ret;
 139         tracing_start_cmdline_record();
 140
 141         return 0;
 142 }
 143
 144 static void graph_trace_reset(struct trace_array *tr)
 145 {
 146         tracing_stop_cmdline_record();
 147         unregister_ftrace_graph();
 148 }
 149
 150 static inline int log10_cpu(int nb)
 151 {
 152         if (nb / 100)
 153                 return 3;
 154         if (nb / 10)
 155                 return 2;
 156         return 1;
 157 }
 158
 159 static enum print_line_t
 160 print_graph_cpu(struct trace_seq *s, int cpu)
 161 {
 162         int i;
 163         int ret;
 164         int log10_this = log10_cpu(cpu);
 165         int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));
 166
 167
 168         /*
 169          * Start with a space character - to make it stand out
 170          * to the right a bit when trace output is pasted into
 171          * email:
 172          */
 173         ret = trace_seq_printf(s, " ");
 174
 175         /*
 176          * Tricky - we space the CPU field according to the max
 177          * number of online CPUs. On a 2-cpu system it would take
 178          * a maximum of 1 digit - on a 128 cpu system it would
 179          * take up to 3 digits:
 180          */
 181         for (i = 0; i < log10_all - log10_this; i++) {
 182                 ret = trace_seq_printf(s, " ");
 183                 if (!ret)
 184                         return TRACE_TYPE_PARTIAL_LINE;
 185         }
 186         ret = trace_seq_printf(s, "%d) ", cpu);
 187         if (!ret)
 188                 return TRACE_TYPE_PARTIAL_LINE;
 189
 190         return TRACE_TYPE_HANDLED;
 191 }
 192
 193 #define TRACE_GRAPH_PROCINFO_LENGTH     14
 194
 195 static enum print_line_t
 196 print_graph_proc(struct trace_seq *s, pid_t pid)
 197 {
 198         char comm[TASK_COMM_LEN];
 199         /* sign + log10(MAX_INT) + '\0' */
 200         char pid_str[11];
 201         int spaces = 0;
 202         int ret;
 203         int len;
 204         int i;
 205
 206         trace_find_cmdline(pid, comm);
 207         comm[7] = '\0';
 208         sprintf(pid_str, "%d", pid);
 209
 210         /* 1 stands for the "-" character */
 211         len = strlen(comm) + strlen(pid_str) + 1;
 212
 213         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
 214                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
 215
 216         /* First spaces to align center */
 217         for (i = 0; i < spaces / 2; i++) {
 218                 ret = trace_seq_printf(s, " ");
 219                 if (!ret)
 220                         return TRACE_TYPE_PARTIAL_LINE;
 221         }
 222
 223         ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
 224         if (!ret)
 225                 return TRACE_TYPE_PARTIAL_LINE;
 226
 227         /* Last spaces to align center */
 228         for (i = 0; i < spaces - (spaces / 2); i++) {
 229                 ret = trace_seq_printf(s, " ");
 230                 if (!ret)
 231                         return TRACE_TYPE_PARTIAL_LINE;
 232         }
 233         return TRACE_TYPE_HANDLED;
 234 }
 235
 236
 237 /* If the pid changed since the last trace, output this event */
 238 static enum print_line_t
 239 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
 240 {
 241         pid_t prev_pid;
 242         pid_t *last_pid;
 243         int ret;
 244
 245         if (!data)
 246                 return TRACE_TYPE_HANDLED;
 247
 248         last_pid = &(per_cpu_ptr(data, cpu)->last_pid);
 249
 250         if (*last_pid == pid)
 251                 return TRACE_TYPE_HANDLED;
 252
 253         prev_pid = *last_pid;
 254         *last_pid = pid;
 255
 256         if (prev_pid == -1)
 257                 return TRACE_TYPE_HANDLED;
 258 /*
 259  * Context-switch trace line:
 260
 261  ------------------------------------------
 262  | 1)  migration/0--1  =>  sshd-1755
 263  ------------------------------------------
 264
 265  */
 266         ret = trace_seq_printf(s,
 267                 " ------------------------------------------\n");
 268         if (!ret)
 269                 return TRACE_TYPE_PARTIAL_LINE;
 270
 271         ret = print_graph_cpu(s, cpu);
 272         if (ret == TRACE_TYPE_PARTIAL_LINE)
 273                 return TRACE_TYPE_PARTIAL_LINE;
 274
 275         ret = print_graph_proc(s, prev_pid);
 276         if (ret == TRACE_TYPE_PARTIAL_LINE)
 277                 return TRACE_TYPE_PARTIAL_LINE;
 278
 279         ret = trace_seq_printf(s, " => ");
 280         if (!ret)
 281                 return TRACE_TYPE_PARTIAL_LINE;
 282
 283         ret = print_graph_proc(s, pid);
 284         if (ret == TRACE_TYPE_PARTIAL_LINE)
 285                 return TRACE_TYPE_PARTIAL_LINE;
 286
 287         ret = trace_seq_printf(s,
 288                 "\n ------------------------------------------\n\n");
 289         if (!ret)
 290                 return TRACE_TYPE_PARTIAL_LINE;
 291
 292         return TRACE_TYPE_HANDLED;
 293 }
 294
 295 static struct ftrace_graph_ret_entry *
 296 get_return_for_leaf(struct trace_iterator *iter,
 297                 struct ftrace_graph_ent_entry *curr)
 298 {
 299         struct ring_buffer_iter *ring_iter;
 300         struct ring_buffer_event *event;
 301         struct ftrace_graph_ret_entry *next;
 302
 303         ring_iter = iter->buffer_iter[iter->cpu];
 304
 305         /* First peek to compare current entry and the next one */
 306         if (ring_iter)
 307                 event = ring_buffer_iter_peek(ring_iter, NULL);
 308         else {
 309         /* We need to consume the current entry to see the next one */
 310                 ring_buffer_consume(iter->tr->buffer, iter->cpu, NULL);
 311                 event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
 312                                         NULL);
 313         }
 314
 315         if (!event)
 316                 return NULL;
 317
 318         next = ring_buffer_event_data(event);
 319
 320         if (next->ent.type != TRACE_GRAPH_RET)
 321                 return NULL;
 322
 323         if (curr->ent.pid != next->ent.pid ||
 324                         curr->graph_ent.func != next->ret.func)
 325                 return NULL;
 326
 327         /* this is a leaf, now advance the iterator */
 328         if (ring_iter)
 329                 ring_buffer_read(ring_iter, NULL);
 330
 331         return next;
 332 }
 333
 334 /* Signal a overhead of time execution to the output */
 335 static int
 336 print_graph_overhead(unsigned long long duration, struct trace_seq *s)
 337 {
 338         /* If duration disappear, we don't need anything */
 339         if (!(tracer_flags.val & TRACE_GRAPH_PRINT_DURATION))
 340                 return 1;
 341
 342         /* Non nested entry or return */
 343         if (duration == -1)
 344                 return trace_seq_printf(s, "  ");
 345
 346         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 347                 /* Duration exceeded 100 msecs */
 348                 if (duration > 100000ULL)
 349                         return trace_seq_printf(s, "! ");
 350
 351                 /* Duration exceeded 10 msecs */
 352                 if (duration > 10000ULL)
 353                         return trace_seq_printf(s, "+ ");
 354         }
 355
 356         return trace_seq_printf(s, "  ");
 357 }
 358
 359 static int print_graph_abs_time(u64 t, struct trace_seq *s)
 360 {
 361         unsigned long usecs_rem;
 362
 363         usecs_rem = do_div(t, NSEC_PER_SEC);
 364         usecs_rem /= 1000;
 365
 366         return trace_seq_printf(s, "%5lu.%06lu |  ",
 367                         (unsigned long)t, usecs_rem);
 368 }
 369
 370 static enum print_line_t
 371 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 372                 enum trace_type type, int cpu, pid_t pid)
 373 {
 374         int ret;
 375         struct trace_seq *s = &iter->seq;
 376
 377         if (addr < (unsigned long)__irqentry_text_start ||
 378                 addr >= (unsigned long)__irqentry_text_end)
 379                 return TRACE_TYPE_UNHANDLED;
 380
 381         /* Absolute time */
 382         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
 383                 ret = print_graph_abs_time(iter->ts, s);
 384                 if (!ret)
 385                         return TRACE_TYPE_PARTIAL_LINE;
 386         }
 387
 388         /* Cpu */
 389         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 390                 ret = print_graph_cpu(s, cpu);
 391                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 392                         return TRACE_TYPE_PARTIAL_LINE;
 393         }
 394         /* Proc */
 395         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 396                 ret = print_graph_proc(s, pid);
 397                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 398                         return TRACE_TYPE_PARTIAL_LINE;
 399                 ret = trace_seq_printf(s, " | ");
 400                 if (!ret)
 401                         return TRACE_TYPE_PARTIAL_LINE;
 402         }
 403
 404         /* No overhead */
 405         ret = print_graph_overhead(-1, s);
 406         if (!ret)
 407                 return TRACE_TYPE_PARTIAL_LINE;
 408
 409         if (type == TRACE_GRAPH_ENT)
 410                 ret = trace_seq_printf(s, "==========>");
 411         else
 412                 ret = trace_seq_printf(s, "<==========");
 413
 414         if (!ret)
 415                 return TRACE_TYPE_PARTIAL_LINE;
 416
 417         /* Don't close the duration column if haven't one */
 418         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 419                 trace_seq_printf(s, " |");
 420         ret = trace_seq_printf(s, "\n");
 421
 422         if (!ret)
 423                 return TRACE_TYPE_PARTIAL_LINE;
 424         return TRACE_TYPE_HANDLED;
 425 }
 426
 427 static enum print_line_t
 428 print_graph_duration(unsigned long long duration, struct trace_seq *s)
 429 {
 430         unsigned long nsecs_rem = do_div(duration, 1000);
 431         /* log10(ULONG_MAX) + '\0' */
 432         char msecs_str[21];
 433         char nsecs_str[5];
 434         int ret, len;
 435         int i;
 436
 437         sprintf(msecs_str, "%lu", (unsigned long) duration);
 438
 439         /* Print msecs */
 440         ret = trace_seq_printf(s, "%s", msecs_str);
 441         if (!ret)
 442                 return TRACE_TYPE_PARTIAL_LINE;
 443
 444         len = strlen(msecs_str);
 445
 446         /* Print nsecs (we don't want to exceed 7 numbers) */
 447         if (len < 7) {
 448                 snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
 449                 ret = trace_seq_printf(s, ".%s", nsecs_str);
 450                 if (!ret)
 451                         return TRACE_TYPE_PARTIAL_LINE;
 452                 len += strlen(nsecs_str);
 453         }
 454
 455         ret = trace_seq_printf(s, " us ");
 456         if (!ret)
 457                 return TRACE_TYPE_PARTIAL_LINE;
 458
 459         /* Print remaining spaces to fit the row's width */
 460         for (i = len; i < 7; i++) {
 461                 ret = trace_seq_printf(s, " ");
 462                 if (!ret)
 463                         return TRACE_TYPE_PARTIAL_LINE;
 464         }
 465
 466         ret = trace_seq_printf(s, "|  ");
 467         if (!ret)
 468                 return TRACE_TYPE_PARTIAL_LINE;
 469         return TRACE_TYPE_HANDLED;
 470
 471 }
 472
 473 /* Case of a leaf function on its call entry */
 474 static enum print_line_t
 475 print_graph_entry_leaf(struct trace_iterator *iter,
 476                 struct ftrace_graph_ent_entry *entry,
 477                 struct ftrace_graph_ret_entry *ret_entry, struct trace_seq *s)
 478 {
 479         struct fgraph_data *data = iter->private;
 480         struct ftrace_graph_ret *graph_ret;
 481         struct ftrace_graph_ent *call;
 482         unsigned long long duration;
 483         int ret;
 484         int i;
 485
 486         graph_ret = &ret_entry->ret;
 487         call = &entry->graph_ent;
 488         duration = graph_ret->rettime - graph_ret->calltime;
 489
 490         if (data) {
 491                 int cpu = iter->cpu;
 492                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 493
 494                 /*
 495                  * Comments display at + 1 to depth. Since
 496                  * this is a leaf function, keep the comments
 497                  * equal to this depth.
 498                  */
 499                 *depth = call->depth - 1;
 500         }
 501
 502         /* Overhead */
 503         ret = print_graph_overhead(duration, s);
 504         if (!ret)
 505                 return TRACE_TYPE_PARTIAL_LINE;
 506
 507         /* Duration */
 508         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 509                 ret = print_graph_duration(duration, s);
 510                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 511                         return TRACE_TYPE_PARTIAL_LINE;
 512         }
 513
 514         /* Function */
 515         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 516                 ret = trace_seq_printf(s, " ");
 517                 if (!ret)
 518                         return TRACE_TYPE_PARTIAL_LINE;
 519         }
 520
 521         ret = seq_print_ip_sym(s, call->func, 0);
 522         if (!ret)
 523                 return TRACE_TYPE_PARTIAL_LINE;
 524
 525         ret = trace_seq_printf(s, "();\n");
 526         if (!ret)
 527                 return TRACE_TYPE_PARTIAL_LINE;
 528
 529         return TRACE_TYPE_HANDLED;
 530 }
 531
 532 static enum print_line_t
 533 print_graph_entry_nested(struct trace_iterator *iter,
 534                          struct ftrace_graph_ent_entry *entry,
 535                          struct trace_seq *s, int cpu)
 536 {
 537         struct ftrace_graph_ent *call = &entry->graph_ent;
 538         struct fgraph_data *data = iter->private;
 539         int ret;
 540         int i;
 541
 542         if (data) {
 543                 int cpu = iter->cpu;
 544                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 545
 546                 *depth = call->depth;
 547         }
 548
 549         /* No overhead */
 550         ret = print_graph_overhead(-1, s);
 551         if (!ret)
 552                 return TRACE_TYPE_PARTIAL_LINE;
 553
 554         /* No time */
 555         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 556                 ret = trace_seq_printf(s, "            |  ");
 557                 if (!ret)
 558                         return TRACE_TYPE_PARTIAL_LINE;
 559         }
 560
 561         /* Function */
 562         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 563                 ret = trace_seq_printf(s, " ");
 564                 if (!ret)
 565                         return TRACE_TYPE_PARTIAL_LINE;
 566         }
 567
 568         ret = seq_print_ip_sym(s, call->func, 0);
 569         if (!ret)
 570                 return TRACE_TYPE_PARTIAL_LINE;
 571
 572         ret = trace_seq_printf(s, "() {\n");
 573         if (!ret)
 574                 return TRACE_TYPE_PARTIAL_LINE;
 575
 576         /*
 577          * we already consumed the current entry to check the next one
 578          * and see if this is a leaf.
 579          */
 580         return TRACE_TYPE_NO_CONSUME;
 581 }
 582
 583 static enum print_line_t
 584 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
 585                      int type, unsigned long addr)
 586 {
 587         struct fgraph_data *data = iter->private;
 588         struct trace_entry *ent = iter->ent;
 589         int cpu = iter->cpu;
 590         int ret;
 591
 592         /* Pid */
 593         if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
 594                 return TRACE_TYPE_PARTIAL_LINE;
 595
 596         if (type) {
 597                 /* Interrupt */
 598                 ret = print_graph_irq(iter, addr, type, cpu, ent->pid);
 599                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 600                         return TRACE_TYPE_PARTIAL_LINE;
 601         }
 602
 603         /* Absolute time */
 604         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
 605                 ret = print_graph_abs_time(iter->ts, s);
 606                 if (!ret)
 607                         return TRACE_TYPE_PARTIAL_LINE;
 608         }
 609
 610         /* Cpu */
 611         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 612                 ret = print_graph_cpu(s, cpu);
 613                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 614                         return TRACE_TYPE_PARTIAL_LINE;
 615         }
 616
 617         /* Proc */
 618         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 619                 ret = print_graph_proc(s, ent->pid);
 620                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 621                         return TRACE_TYPE_PARTIAL_LINE;
 622
 623                 ret = trace_seq_printf(s, " | ");
 624                 if (!ret)
 625                         return TRACE_TYPE_PARTIAL_LINE;
 626         }
 627
 628         return 0;
 629 }
 630
 631 static enum print_line_t
 632 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
 633                         struct trace_iterator *iter)
 634 {
 635         int cpu = iter->cpu;
 636         struct ftrace_graph_ent *call = &field->graph_ent;
 637         struct ftrace_graph_ret_entry *leaf_ret;
 638
 639         if (print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func))
 640                 return TRACE_TYPE_PARTIAL_LINE;
 641
 642         leaf_ret = get_return_for_leaf(iter, field);
 643         if (leaf_ret)
 644                 return print_graph_entry_leaf(iter, field, leaf_ret, s);
 645         else
 646                 return print_graph_entry_nested(iter, field, s, cpu);
 647
 648 }
 649
 650 static enum print_line_t
 651 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 652                    struct trace_entry *ent, struct trace_iterator *iter)
 653 {
 654         unsigned long long duration = trace->rettime - trace->calltime;
 655         struct fgraph_data *data = iter->private;
 656         pid_t pid = ent->pid;
 657         int cpu = iter->cpu;
 658         int ret;
 659         int i;
 660
 661         if (data) {
 662                 int cpu = iter->cpu;
 663                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 664
 665                 /*
 666                  * Comments display at + 1 to depth. This is the
 667                  * return from a function, we now want the comments
 668                  * to display at the same level of the bracket.
 669                  */
 670                 *depth = trace->depth - 1;
 671         }
 672
 673         if (print_graph_prologue(iter, s, 0, 0))
 674                 return TRACE_TYPE_PARTIAL_LINE;
 675
 676         /* Overhead */
 677         ret = print_graph_overhead(duration, s);
 678         if (!ret)
 679                 return TRACE_TYPE_PARTIAL_LINE;
 680
 681         /* Duration */
 682         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 683                 ret = print_graph_duration(duration, s);
 684                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 685                         return TRACE_TYPE_PARTIAL_LINE;
 686         }
 687
 688         /* Closing brace */
 689         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
 690                 ret = trace_seq_printf(s, " ");
 691                 if (!ret)
 692                         return TRACE_TYPE_PARTIAL_LINE;
 693         }
 694
 695         ret = trace_seq_printf(s, "}\n");
 696         if (!ret)
 697                 return TRACE_TYPE_PARTIAL_LINE;
 698
 699         /* Overrun */
 700         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
 701                 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
 702                                         trace->overrun);
 703                 if (!ret)
 704                         return TRACE_TYPE_PARTIAL_LINE;
 705         }
 706
 707         ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET, cpu, pid);
 708         if (ret == TRACE_TYPE_PARTIAL_LINE)
 709                 return TRACE_TYPE_PARTIAL_LINE;
 710
 711         return TRACE_TYPE_HANDLED;
 712 }
 713
 714 static enum print_line_t
 715 print_graph_comment(struct trace_seq *s,  struct trace_entry *ent,
 716                     struct trace_iterator *iter)
 717 {
 718         unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
 719         struct fgraph_data *data = iter->private;
 720         struct trace_event *event;
 721         int depth = 0;
 722         int ret;
 723         int i;
 724
 725         if (data)
 726                 depth = per_cpu_ptr(data, iter->cpu)->depth;
 727
 728         if (print_graph_prologue(iter, s, 0, 0))
 729                 return TRACE_TYPE_PARTIAL_LINE;
 730
 731         /* No overhead */
 732         ret = print_graph_overhead(-1, s);
 733         if (!ret)
 734                 return TRACE_TYPE_PARTIAL_LINE;
 735
 736         /* No time */
 737         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 738                 ret = trace_seq_printf(s, "            |  ");
 739                 if (!ret)
 740                         return TRACE_TYPE_PARTIAL_LINE;
 741         }
 742
 743         /* Indentation */
 744         if (depth > 0)
 745                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
 746                         ret = trace_seq_printf(s, " ");
 747                         if (!ret)
 748                                 return TRACE_TYPE_PARTIAL_LINE;
 749                 }
 750
 751         /* The comment */
 752         ret = trace_seq_printf(s, "/* ");
 753         if (!ret)
 754                 return TRACE_TYPE_PARTIAL_LINE;
 755
 756         switch (iter->ent->type) {
 757         case TRACE_BPRINT:
 758                 ret = trace_print_bprintk_msg_only(iter);
 759                 if (ret != TRACE_TYPE_HANDLED)
 760                         return ret;
 761                 break;
 762         case TRACE_PRINT:
 763                 ret = trace_print_printk_msg_only(iter);
 764                 if (ret != TRACE_TYPE_HANDLED)
 765                         return ret;
 766                 break;
 767         default:
 768                 event = ftrace_find_event(ent->type);
 769                 if (!event)
 770                         return TRACE_TYPE_UNHANDLED;
 771
 772                 ret = event->trace(iter, sym_flags);
 773                 if (ret != TRACE_TYPE_HANDLED)
 774                         return ret;
 775         }
 776
 777         /* Strip ending newline */
 778         if (s->buffer[s->len - 1] == '\n') {
 779                 s->buffer[s->len - 1] = '\0';
 780                 s->len--;
 781         }
 782
 783         ret = trace_seq_printf(s, " */\n");
 784         if (!ret)
 785                 return TRACE_TYPE_PARTIAL_LINE;
 786
 787         return TRACE_TYPE_HANDLED;
 788 }
 789
 790
 791 enum print_line_t
 792 print_graph_function(struct trace_iterator *iter)
 793 {
 794         struct trace_entry *entry = iter->ent;
 795         struct trace_seq *s = &iter->seq;
 796
 797         switch (entry->type) {
 798         case TRACE_GRAPH_ENT: {
 799                 struct ftrace_graph_ent_entry *field;
 800                 trace_assign_type(field, entry);
 801                 return print_graph_entry(field, s, iter);
 802         }
 803         case TRACE_GRAPH_RET: {
 804                 struct ftrace_graph_ret_entry *field;
 805                 trace_assign_type(field, entry);
 806                 return print_graph_return(&field->ret, s, entry, iter);
 807         }
 808         default:
 809                 return print_graph_comment(s, entry, iter);
 810         }
 811
 812         return TRACE_TYPE_HANDLED;
 813 }
 814
 815 static void print_graph_headers(struct seq_file *s)
 816 {
 817         /* 1st line */
 818         seq_printf(s, "# ");
 819         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
 820                 seq_printf(s, "     TIME       ");
 821         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 822                 seq_printf(s, "CPU");
 823         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 824                 seq_printf(s, "  TASK/PID      ");
 825         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 826                 seq_printf(s, "  DURATION   ");
 827         seq_printf(s, "               FUNCTION CALLS\n");
 828
 829         /* 2nd line */
 830         seq_printf(s, "# ");
 831         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
 832                 seq_printf(s, "      |         ");
 833         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 834                 seq_printf(s, "|  ");
 835         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 836                 seq_printf(s, "  |    |        ");
 837         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 838                 seq_printf(s, "   |   |      ");
 839         seq_printf(s, "               |   |   |   |\n");
 840 }
 841
 842 static void graph_trace_open(struct trace_iterator *iter)
 843 {
 844         /* pid and depth on the last trace processed */
 845         struct fgraph_data *data = alloc_percpu(struct fgraph_data);
 846         int cpu;
 847
 848         if (!data)
 849                 pr_warning("function graph tracer: not enough memory\n");
 850         else
 851                 for_each_possible_cpu(cpu) {
 852                         pid_t *pid = &(per_cpu_ptr(data, cpu)->last_pid);
 853                         int *depth = &(per_cpu_ptr(data, cpu)->depth);
 854                         *pid = -1;
 855                         *depth = 0;
 856                 }
 857
 858         iter->private = data;
 859 }
 860
 861 static void graph_trace_close(struct trace_iterator *iter)
 862 {
 863         free_percpu(iter->private);
 864 }
 865
 866 static struct tracer graph_trace __read_mostly = {
 867         .name           = "function_graph",
 868         .open           = graph_trace_open,
 869         .close          = graph_trace_close,
 870         .wait_pipe      = poll_wait_pipe,
 871         .init           = graph_trace_init,
 872         .reset          = graph_trace_reset,
 873         .print_line     = print_graph_function,
 874         .print_header   = print_graph_headers,
 875         .flags          = &tracer_flags,
 876 #ifdef CONFIG_FTRACE_SELFTEST
 877         .selftest       = trace_selftest_startup_function_graph,
 878 #endif
 879 };
 880
 881 static __init int init_graph_trace(void)
 882 {
 883         return register_tracer(&graph_trace);
 884 }
 885
 886 device_initcall(init_graph_trace);