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 func, int *depth,
  61                          unsigned long frame_pointer)
  62 {
  63         unsigned long long calltime;
  64         int index;
  65
  66         if (!current->ret_stack)
  67                 return -EBUSY;
  68
  69         /*
  70          * We must make sure the ret_stack is tested before we read
  71          * anything else.
  72          */
  73         smp_rmb();
  74
  75         /* The return trace stack is full */
  76         if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
  77                 atomic_inc(&current->trace_overrun);
  78                 return -EBUSY;
  79         }
  80
  81         calltime = trace_clock_local();
  82
  83         index = ++current->curr_ret_stack;
  84         barrier();
  85         current->ret_stack[index].ret = ret;
  86         current->ret_stack[index].func = func;
  87         current->ret_stack[index].calltime = calltime;
  88         current->ret_stack[index].subtime = 0;
  89         current->ret_stack[index].fp = frame_pointer;
  90         *depth = index;
  91
  92         return 0;
  93 }
  94
  95 /* Retrieve a function return address to the trace stack on thread info.*/
  96 static void
  97 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
  98                         unsigned long frame_pointer)
  99 {
 100         int index;
 101
 102         index = current->curr_ret_stack;
 103
 104         if (unlikely(index < 0)) {
 105                 ftrace_graph_stop();
 106                 WARN_ON(1);
 107                 /* Might as well panic, otherwise we have no where to go */
 108                 *ret = (unsigned long)panic;
 109                 return;
 110         }
 111
 112 #ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
 113         /*
 114          * The arch may choose to record the frame pointer used
 115          * and check it here to make sure that it is what we expect it
 116          * to be. If gcc does not set the place holder of the return
 117          * address in the frame pointer, and does a copy instead, then
 118          * the function graph trace will fail. This test detects this
 119          * case.
 120          *
 121          * Currently, x86_32 with optimize for size (-Os) makes the latest
 122          * gcc do the above.
 123          */
 124         if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
 125                 ftrace_graph_stop();
 126                 WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
 127                      "  from func %pF return to %lx\n",
 128                      current->ret_stack[index].fp,
 129                      frame_pointer,
 130                      (void *)current->ret_stack[index].func,
 131                      current->ret_stack[index].ret);
 132                 *ret = (unsigned long)panic;
 133                 return;
 134         }
 135 #endif
 136
 137         *ret = current->ret_stack[index].ret;
 138         trace->func = current->ret_stack[index].func;
 139         trace->calltime = current->ret_stack[index].calltime;
 140         trace->overrun = atomic_read(&current->trace_overrun);
 141         trace->depth = index;
 142 }
 143
 144 /*
 145  * Send the trace to the ring-buffer.
 146  * @return the original return address.
 147  */
 148 unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
 149 {
 150         struct ftrace_graph_ret trace;
 151         unsigned long ret;
 152
 153         ftrace_pop_return_trace(&trace, &ret, frame_pointer);
 154         trace.rettime = trace_clock_local();
 155         ftrace_graph_return(&trace);
 156         barrier();
 157         current->curr_ret_stack--;
 158
 159         if (unlikely(!ret)) {
 160                 ftrace_graph_stop();
 161                 WARN_ON(1);
 162                 /* Might as well panic. What else to do? */
 163                 ret = (unsigned long)panic;
 164         }
 165
 166         return ret;
 167 }
 168
 169 static int graph_trace_init(struct trace_array *tr)
 170 {
 171         int ret = register_ftrace_graph(&trace_graph_return,
 172                                         &trace_graph_entry);
 173         if (ret)
 174                 return ret;
 175         tracing_start_cmdline_record();
 176
 177         return 0;
 178 }
 179
 180 static void graph_trace_reset(struct trace_array *tr)
 181 {
 182         tracing_stop_cmdline_record();
 183         unregister_ftrace_graph();
 184 }
 185
 186 static inline int log10_cpu(int nb)
 187 {
 188         if (nb / 100)
 189                 return 3;
 190         if (nb / 10)
 191                 return 2;
 192         return 1;
 193 }
 194
 195 static enum print_line_t
 196 print_graph_cpu(struct trace_seq *s, int cpu)
 197 {
 198         int i;
 199         int ret;
 200         int log10_this = log10_cpu(cpu);
 201         int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));
 202
 203
 204         /*
 205          * Start with a space character - to make it stand out
 206          * to the right a bit when trace output is pasted into
 207          * email:
 208          */
 209         ret = trace_seq_printf(s, " ");
 210
 211         /*
 212          * Tricky - we space the CPU field according to the max
 213          * number of online CPUs. On a 2-cpu system it would take
 214          * a maximum of 1 digit - on a 128 cpu system it would
 215          * take up to 3 digits:
 216          */
 217         for (i = 0; i < log10_all - log10_this; i++) {
 218                 ret = trace_seq_printf(s, " ");
 219                 if (!ret)
 220                         return TRACE_TYPE_PARTIAL_LINE;
 221         }
 222         ret = trace_seq_printf(s, "%d) ", cpu);
 223         if (!ret)
 224                 return TRACE_TYPE_PARTIAL_LINE;
 225
 226         return TRACE_TYPE_HANDLED;
 227 }
 228
 229 #define TRACE_GRAPH_PROCINFO_LENGTH     14
 230
 231 static enum print_line_t
 232 print_graph_proc(struct trace_seq *s, pid_t pid)
 233 {
 234         char comm[TASK_COMM_LEN];
 235         /* sign + log10(MAX_INT) + '\0' */
 236         char pid_str[11];
 237         int spaces = 0;
 238         int ret;
 239         int len;
 240         int i;
 241
 242         trace_find_cmdline(pid, comm);
 243         comm[7] = '\0';
 244         sprintf(pid_str, "%d", pid);
 245
 246         /* 1 stands for the "-" character */
 247         len = strlen(comm) + strlen(pid_str) + 1;
 248
 249         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
 250                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
 251
 252         /* First spaces to align center */
 253         for (i = 0; i < spaces / 2; i++) {
 254                 ret = trace_seq_printf(s, " ");
 255                 if (!ret)
 256                         return TRACE_TYPE_PARTIAL_LINE;
 257         }
 258
 259         ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
 260         if (!ret)
 261                 return TRACE_TYPE_PARTIAL_LINE;
 262
 263         /* Last spaces to align center */
 264         for (i = 0; i < spaces - (spaces / 2); i++) {
 265                 ret = trace_seq_printf(s, " ");
 266                 if (!ret)
 267                         return TRACE_TYPE_PARTIAL_LINE;
 268         }
 269         return TRACE_TYPE_HANDLED;
 270 }
 271
 272
 273 /* If the pid changed since the last trace, output this event */
 274 static enum print_line_t
 275 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
 276 {
 277         pid_t prev_pid;
 278         pid_t *last_pid;
 279         int ret;
 280
 281         if (!data)
 282                 return TRACE_TYPE_HANDLED;
 283
 284         last_pid = &(per_cpu_ptr(data, cpu)->last_pid);
 285
 286         if (*last_pid == pid)
 287                 return TRACE_TYPE_HANDLED;
 288
 289         prev_pid = *last_pid;
 290         *last_pid = pid;
 291
 292         if (prev_pid == -1)
 293                 return TRACE_TYPE_HANDLED;
 294 /*
 295  * Context-switch trace line:
 296
 297  ------------------------------------------
 298  | 1)  migration/0--1  =>  sshd-1755
 299  ------------------------------------------
 300
 301  */
 302         ret = trace_seq_printf(s,
 303                 " ------------------------------------------\n");
 304         if (!ret)
 305                 return TRACE_TYPE_PARTIAL_LINE;
 306
 307         ret = print_graph_cpu(s, cpu);
 308         if (ret == TRACE_TYPE_PARTIAL_LINE)
 309                 return TRACE_TYPE_PARTIAL_LINE;
 310
 311         ret = print_graph_proc(s, prev_pid);
 312         if (ret == TRACE_TYPE_PARTIAL_LINE)
 313                 return TRACE_TYPE_PARTIAL_LINE;
 314
 315         ret = trace_seq_printf(s, " => ");
 316         if (!ret)
 317                 return TRACE_TYPE_PARTIAL_LINE;
 318
 319         ret = print_graph_proc(s, pid);
 320         if (ret == TRACE_TYPE_PARTIAL_LINE)
 321                 return TRACE_TYPE_PARTIAL_LINE;
 322
 323         ret = trace_seq_printf(s,
 324                 "\n ------------------------------------------\n\n");
 325         if (!ret)
 326                 return TRACE_TYPE_PARTIAL_LINE;
 327
 328         return TRACE_TYPE_HANDLED;
 329 }
 330
 331 static struct ftrace_graph_ret_entry *
 332 get_return_for_leaf(struct trace_iterator *iter,
 333                 struct ftrace_graph_ent_entry *curr)
 334 {
 335         struct ring_buffer_iter *ring_iter;
 336         struct ring_buffer_event *event;
 337         struct ftrace_graph_ret_entry *next;
 338
 339         ring_iter = iter->buffer_iter[iter->cpu];
 340
 341         /* First peek to compare current entry and the next one */
 342         if (ring_iter)
 343                 event = ring_buffer_iter_peek(ring_iter, NULL);
 344         else {
 345         /* We need to consume the current entry to see the next one */
 346                 ring_buffer_consume(iter->tr->buffer, iter->cpu, NULL);
 347                 event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
 348                                         NULL);
 349         }
 350
 351         if (!event)
 352                 return NULL;
 353
 354         next = ring_buffer_event_data(event);
 355
 356         if (next->ent.type != TRACE_GRAPH_RET)
 357                 return NULL;
 358
 359         if (curr->ent.pid != next->ent.pid ||
 360                         curr->graph_ent.func != next->ret.func)
 361                 return NULL;
 362
 363         /* this is a leaf, now advance the iterator */
 364         if (ring_iter)
 365                 ring_buffer_read(ring_iter, NULL);
 366
 367         return next;
 368 }
 369
 370 /* Signal a overhead of time execution to the output */
 371 static int
 372 print_graph_overhead(unsigned long long duration, struct trace_seq *s)
 373 {
 374         /* If duration disappear, we don't need anything */
 375         if (!(tracer_flags.val & TRACE_GRAPH_PRINT_DURATION))
 376                 return 1;
 377
 378         /* Non nested entry or return */
 379         if (duration == -1)
 380                 return trace_seq_printf(s, "  ");
 381
 382         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 383                 /* Duration exceeded 100 msecs */
 384                 if (duration > 100000ULL)
 385                         return trace_seq_printf(s, "! ");
 386
 387                 /* Duration exceeded 10 msecs */
 388                 if (duration > 10000ULL)
 389                         return trace_seq_printf(s, "+ ");
 390         }
 391
 392         return trace_seq_printf(s, "  ");
 393 }
 394
 395 static int print_graph_abs_time(u64 t, struct trace_seq *s)
 396 {
 397         unsigned long usecs_rem;
 398
 399         usecs_rem = do_div(t, NSEC_PER_SEC);
 400         usecs_rem /= 1000;
 401
 402         return trace_seq_printf(s, "%5lu.%06lu |  ",
 403                         (unsigned long)t, usecs_rem);
 404 }
 405
 406 static enum print_line_t
 407 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 408                 enum trace_type type, int cpu, pid_t pid)
 409 {
 410         int ret;
 411         struct trace_seq *s = &iter->seq;
 412
 413         if (addr < (unsigned long)__irqentry_text_start ||
 414                 addr >= (unsigned long)__irqentry_text_end)
 415                 return TRACE_TYPE_UNHANDLED;
 416
 417         /* Absolute time */
 418         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
 419                 ret = print_graph_abs_time(iter->ts, s);
 420                 if (!ret)
 421                         return TRACE_TYPE_PARTIAL_LINE;
 422         }
 423
 424         /* Cpu */
 425         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 426                 ret = print_graph_cpu(s, cpu);
 427                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 428                         return TRACE_TYPE_PARTIAL_LINE;
 429         }
 430         /* Proc */
 431         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 432                 ret = print_graph_proc(s, pid);
 433                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 434                         return TRACE_TYPE_PARTIAL_LINE;
 435                 ret = trace_seq_printf(s, " | ");
 436                 if (!ret)
 437                         return TRACE_TYPE_PARTIAL_LINE;
 438         }
 439
 440         /* No overhead */
 441         ret = print_graph_overhead(-1, s);
 442         if (!ret)
 443                 return TRACE_TYPE_PARTIAL_LINE;
 444
 445         if (type == TRACE_GRAPH_ENT)
 446                 ret = trace_seq_printf(s, "==========>");
 447         else
 448                 ret = trace_seq_printf(s, "<==========");
 449
 450         if (!ret)
 451                 return TRACE_TYPE_PARTIAL_LINE;
 452
 453         /* Don't close the duration column if haven't one */
 454         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 455                 trace_seq_printf(s, " |");
 456         ret = trace_seq_printf(s, "\n");
 457
 458         if (!ret)
 459                 return TRACE_TYPE_PARTIAL_LINE;
 460         return TRACE_TYPE_HANDLED;
 461 }
 462
 463 enum print_line_t
 464 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 465 {
 466         unsigned long nsecs_rem = do_div(duration, 1000);
 467         /* log10(ULONG_MAX) + '\0' */
 468         char msecs_str[21];
 469         char nsecs_str[5];
 470         int ret, len;
 471         int i;
 472
 473         sprintf(msecs_str, "%lu", (unsigned long) duration);
 474
 475         /* Print msecs */
 476         ret = trace_seq_printf(s, "%s", msecs_str);
 477         if (!ret)
 478                 return TRACE_TYPE_PARTIAL_LINE;
 479
 480         len = strlen(msecs_str);
 481
 482         /* Print nsecs (we don't want to exceed 7 numbers) */
 483         if (len < 7) {
 484                 snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
 485                 ret = trace_seq_printf(s, ".%s", nsecs_str);
 486                 if (!ret)
 487                         return TRACE_TYPE_PARTIAL_LINE;
 488                 len += strlen(nsecs_str);
 489         }
 490
 491         ret = trace_seq_printf(s, " us ");
 492         if (!ret)
 493                 return TRACE_TYPE_PARTIAL_LINE;
 494
 495         /* Print remaining spaces to fit the row's width */
 496         for (i = len; i < 7; i++) {
 497                 ret = trace_seq_printf(s, " ");
 498                 if (!ret)
 499                         return TRACE_TYPE_PARTIAL_LINE;
 500         }
 501         return TRACE_TYPE_HANDLED;
 502 }
 503
 504 static enum print_line_t
 505 print_graph_duration(unsigned long long duration, struct trace_seq *s)
 506 {
 507         int ret;
 508
 509         ret = trace_print_graph_duration(duration, s);
 510         if (ret != TRACE_TYPE_HANDLED)
 511                 return ret;
 512
 513         ret = trace_seq_printf(s, "|  ");
 514         if (!ret)
 515                 return TRACE_TYPE_PARTIAL_LINE;
 516
 517         return TRACE_TYPE_HANDLED;
 518 }
 519
 520 /* Case of a leaf function on its call entry */
 521 static enum print_line_t
 522 print_graph_entry_leaf(struct trace_iterator *iter,
 523                 struct ftrace_graph_ent_entry *entry,
 524                 struct ftrace_graph_ret_entry *ret_entry, struct trace_seq *s)
 525 {
 526         struct fgraph_data *data = iter->private;
 527         struct ftrace_graph_ret *graph_ret;
 528         struct ftrace_graph_ent *call;
 529         unsigned long long duration;
 530         int ret;
 531         int i;
 532
 533         graph_ret = &ret_entry->ret;
 534         call = &entry->graph_ent;
 535         duration = graph_ret->rettime - graph_ret->calltime;
 536
 537         if (data) {
 538                 int cpu = iter->cpu;
 539                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 540
 541                 /*
 542                  * Comments display at + 1 to depth. Since
 543                  * this is a leaf function, keep the comments
 544                  * equal to this depth.
 545                  */
 546                 *depth = call->depth - 1;
 547         }
 548
 549         /* Overhead */
 550         ret = print_graph_overhead(duration, s);
 551         if (!ret)
 552                 return TRACE_TYPE_PARTIAL_LINE;
 553
 554         /* Duration */
 555         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 556                 ret = print_graph_duration(duration, s);
 557                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 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         return TRACE_TYPE_HANDLED;
 577 }
 578
 579 static enum print_line_t
 580 print_graph_entry_nested(struct trace_iterator *iter,
 581                          struct ftrace_graph_ent_entry *entry,
 582                          struct trace_seq *s, int cpu)
 583 {
 584         struct ftrace_graph_ent *call = &entry->graph_ent;
 585         struct fgraph_data *data = iter->private;
 586         int ret;
 587         int i;
 588
 589         if (data) {
 590                 int cpu = iter->cpu;
 591                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 592
 593                 *depth = call->depth;
 594         }
 595
 596         /* No overhead */
 597         ret = print_graph_overhead(-1, s);
 598         if (!ret)
 599                 return TRACE_TYPE_PARTIAL_LINE;
 600
 601         /* No time */
 602         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 603                 ret = trace_seq_printf(s, "            |  ");
 604                 if (!ret)
 605                         return TRACE_TYPE_PARTIAL_LINE;
 606         }
 607
 608         /* Function */
 609         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 610                 ret = trace_seq_printf(s, " ");
 611                 if (!ret)
 612                         return TRACE_TYPE_PARTIAL_LINE;
 613         }
 614
 615         ret = seq_print_ip_sym(s, call->func, 0);
 616         if (!ret)
 617                 return TRACE_TYPE_PARTIAL_LINE;
 618
 619         ret = trace_seq_printf(s, "() {\n");
 620         if (!ret)
 621                 return TRACE_TYPE_PARTIAL_LINE;
 622
 623         /*
 624          * we already consumed the current entry to check the next one
 625          * and see if this is a leaf.
 626          */
 627         return TRACE_TYPE_NO_CONSUME;
 628 }
 629
 630 static enum print_line_t
 631 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
 632                      int type, unsigned long addr)
 633 {
 634         struct fgraph_data *data = iter->private;
 635         struct trace_entry *ent = iter->ent;
 636         int cpu = iter->cpu;
 637         int ret;
 638
 639         /* Pid */
 640         if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
 641                 return TRACE_TYPE_PARTIAL_LINE;
 642
 643         if (type) {
 644                 /* Interrupt */
 645                 ret = print_graph_irq(iter, addr, type, cpu, ent->pid);
 646                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 647                         return TRACE_TYPE_PARTIAL_LINE;
 648         }
 649
 650         /* Absolute time */
 651         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
 652                 ret = print_graph_abs_time(iter->ts, s);
 653                 if (!ret)
 654                         return TRACE_TYPE_PARTIAL_LINE;
 655         }
 656
 657         /* Cpu */
 658         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 659                 ret = print_graph_cpu(s, cpu);
 660                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 661                         return TRACE_TYPE_PARTIAL_LINE;
 662         }
 663
 664         /* Proc */
 665         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 666                 ret = print_graph_proc(s, ent->pid);
 667                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 668                         return TRACE_TYPE_PARTIAL_LINE;
 669
 670                 ret = trace_seq_printf(s, " | ");
 671                 if (!ret)
 672                         return TRACE_TYPE_PARTIAL_LINE;
 673         }
 674
 675         return 0;
 676 }
 677
 678 static enum print_line_t
 679 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
 680                         struct trace_iterator *iter)
 681 {
 682         int cpu = iter->cpu;
 683         struct ftrace_graph_ent *call = &field->graph_ent;
 684         struct ftrace_graph_ret_entry *leaf_ret;
 685
 686         if (print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func))
 687                 return TRACE_TYPE_PARTIAL_LINE;
 688
 689         leaf_ret = get_return_for_leaf(iter, field);
 690         if (leaf_ret)
 691                 return print_graph_entry_leaf(iter, field, leaf_ret, s);
 692         else
 693                 return print_graph_entry_nested(iter, field, s, cpu);
 694
 695 }
 696
 697 static enum print_line_t
 698 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 699                    struct trace_entry *ent, struct trace_iterator *iter)
 700 {
 701         unsigned long long duration = trace->rettime - trace->calltime;
 702         struct fgraph_data *data = iter->private;
 703         pid_t pid = ent->pid;
 704         int cpu = iter->cpu;
 705         int ret;
 706         int i;
 707
 708         if (data) {
 709                 int cpu = iter->cpu;
 710                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 711
 712                 /*
 713                  * Comments display at + 1 to depth. This is the
 714                  * return from a function, we now want the comments
 715                  * to display at the same level of the bracket.
 716                  */
 717                 *depth = trace->depth - 1;
 718         }
 719
 720         if (print_graph_prologue(iter, s, 0, 0))
 721                 return TRACE_TYPE_PARTIAL_LINE;
 722
 723         /* Overhead */
 724         ret = print_graph_overhead(duration, s);
 725         if (!ret)
 726                 return TRACE_TYPE_PARTIAL_LINE;
 727
 728         /* Duration */
 729         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 730                 ret = print_graph_duration(duration, s);
 731                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 732                         return TRACE_TYPE_PARTIAL_LINE;
 733         }
 734
 735         /* Closing brace */
 736         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
 737                 ret = trace_seq_printf(s, " ");
 738                 if (!ret)
 739                         return TRACE_TYPE_PARTIAL_LINE;
 740         }
 741
 742         ret = trace_seq_printf(s, "}\n");
 743         if (!ret)
 744                 return TRACE_TYPE_PARTIAL_LINE;
 745
 746         /* Overrun */
 747         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
 748                 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
 749                                         trace->overrun);
 750                 if (!ret)
 751                         return TRACE_TYPE_PARTIAL_LINE;
 752         }
 753
 754         ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET, cpu, pid);
 755         if (ret == TRACE_TYPE_PARTIAL_LINE)
 756                 return TRACE_TYPE_PARTIAL_LINE;
 757
 758         return TRACE_TYPE_HANDLED;
 759 }
 760
 761 static enum print_line_t
 762 print_graph_comment(struct trace_seq *s,  struct trace_entry *ent,
 763                     struct trace_iterator *iter)
 764 {
 765         unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
 766         struct fgraph_data *data = iter->private;
 767         struct trace_event *event;
 768         int depth = 0;
 769         int ret;
 770         int i;
 771
 772         if (data)
 773                 depth = per_cpu_ptr(data, iter->cpu)->depth;
 774
 775         if (print_graph_prologue(iter, s, 0, 0))
 776                 return TRACE_TYPE_PARTIAL_LINE;
 777
 778         /* No overhead */
 779         ret = print_graph_overhead(-1, s);
 780         if (!ret)
 781                 return TRACE_TYPE_PARTIAL_LINE;
 782
 783         /* No time */
 784         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 785                 ret = trace_seq_printf(s, "            |  ");
 786                 if (!ret)
 787                         return TRACE_TYPE_PARTIAL_LINE;
 788         }
 789
 790         /* Indentation */
 791         if (depth > 0)
 792                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
 793                         ret = trace_seq_printf(s, " ");
 794                         if (!ret)
 795                                 return TRACE_TYPE_PARTIAL_LINE;
 796                 }
 797
 798         /* The comment */
 799         ret = trace_seq_printf(s, "/* ");
 800         if (!ret)
 801                 return TRACE_TYPE_PARTIAL_LINE;
 802
 803         switch (iter->ent->type) {
 804         case TRACE_BPRINT:
 805                 ret = trace_print_bprintk_msg_only(iter);
 806                 if (ret != TRACE_TYPE_HANDLED)
 807                         return ret;
 808                 break;
 809         case TRACE_PRINT:
 810                 ret = trace_print_printk_msg_only(iter);
 811                 if (ret != TRACE_TYPE_HANDLED)
 812                         return ret;
 813                 break;
 814         default:
 815                 event = ftrace_find_event(ent->type);
 816                 if (!event)
 817                         return TRACE_TYPE_UNHANDLED;
 818
 819                 ret = event->trace(iter, sym_flags);
 820                 if (ret != TRACE_TYPE_HANDLED)
 821                         return ret;
 822         }
 823
 824         /* Strip ending newline */
 825         if (s->buffer[s->len - 1] == '\n') {
 826                 s->buffer[s->len - 1] = '\0';
 827                 s->len--;
 828         }
 829
 830         ret = trace_seq_printf(s, " */\n");
 831         if (!ret)
 832                 return TRACE_TYPE_PARTIAL_LINE;
 833
 834         return TRACE_TYPE_HANDLED;
 835 }
 836
 837
 838 enum print_line_t
 839 print_graph_function(struct trace_iterator *iter)
 840 {
 841         struct trace_entry *entry = iter->ent;
 842         struct trace_seq *s = &iter->seq;
 843
 844         switch (entry->type) {
 845         case TRACE_GRAPH_ENT: {
 846                 /*
 847                  * print_graph_entry() may consume the current event,
 848                  * thus @field may become invalid, so we need to save it.
 849                  * sizeof(struct ftrace_graph_ent_entry) is very small,
 850                  * it can be safely saved at the stack.
 851                  */
 852                 struct ftrace_graph_ent_entry *field, saved;
 853                 trace_assign_type(field, entry);
 854                 saved = *field;
 855                 return print_graph_entry(&saved, s, iter);
 856         }
 857         case TRACE_GRAPH_RET: {
 858                 struct ftrace_graph_ret_entry *field;
 859                 trace_assign_type(field, entry);
 860                 return print_graph_return(&field->ret, s, entry, iter);
 861         }
 862         default:
 863                 return print_graph_comment(s, entry, iter);
 864         }
 865
 866         return TRACE_TYPE_HANDLED;
 867 }
 868
 869 static void print_graph_headers(struct seq_file *s)
 870 {
 871         /* 1st line */
 872         seq_printf(s, "# ");
 873         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
 874                 seq_printf(s, "     TIME       ");
 875         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 876                 seq_printf(s, "CPU");
 877         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 878                 seq_printf(s, "  TASK/PID      ");
 879         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 880                 seq_printf(s, "  DURATION   ");
 881         seq_printf(s, "               FUNCTION CALLS\n");
 882
 883         /* 2nd line */
 884         seq_printf(s, "# ");
 885         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
 886                 seq_printf(s, "      |         ");
 887         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 888                 seq_printf(s, "|  ");
 889         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 890                 seq_printf(s, "  |    |        ");
 891         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 892                 seq_printf(s, "   |   |      ");
 893         seq_printf(s, "               |   |   |   |\n");
 894 }
 895
 896 static void graph_trace_open(struct trace_iterator *iter)
 897 {
 898         /* pid and depth on the last trace processed */
 899         struct fgraph_data *data = alloc_percpu(struct fgraph_data);
 900         int cpu;
 901
 902         if (!data)
 903                 pr_warning("function graph tracer: not enough memory\n");
 904         else
 905                 for_each_possible_cpu(cpu) {
 906                         pid_t *pid = &(per_cpu_ptr(data, cpu)->last_pid);
 907                         int *depth = &(per_cpu_ptr(data, cpu)->depth);
 908                         *pid = -1;
 909                         *depth = 0;
 910                 }
 911
 912         iter->private = data;
 913 }
 914
 915 static void graph_trace_close(struct trace_iterator *iter)
 916 {
 917         free_percpu(iter->private);
 918 }
 919
 920 static struct tracer graph_trace __read_mostly = {
 921         .name           = "function_graph",
 922         .open           = graph_trace_open,
 923         .close          = graph_trace_close,
 924         .wait_pipe      = poll_wait_pipe,
 925         .init           = graph_trace_init,
 926         .reset          = graph_trace_reset,
 927         .print_line     = print_graph_function,
 928         .print_header   = print_graph_headers,
 929         .flags          = &tracer_flags,
 930 #ifdef CONFIG_FTRACE_SELFTEST
 931         .selftest       = trace_selftest_startup_function_graph,
 932 #endif
 933 };
 934
 935 static __init int init_graph_trace(void)
 936 {
 937         return register_tracer(&graph_trace);
 938 }
 939
 940 device_initcall(init_graph_trace);