SAFE public projects git trees. - safe/jmp/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 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 int max_bytes_for_cpu;
 187
 188 static enum print_line_t
 189 print_graph_cpu(struct trace_seq *s, int cpu)
 190 {
 191         int ret;
 192
 193         /*
 194          * Start with a space character - to make it stand out
 195          * to the right a bit when trace output is pasted into
 196          * email:
 197          */
 198         ret = trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
 199         if (!ret)
 200                 return TRACE_TYPE_PARTIAL_LINE;
 201
 202         return TRACE_TYPE_HANDLED;
 203 }
 204
 205 #define TRACE_GRAPH_PROCINFO_LENGTH     14
 206
 207 static enum print_line_t
 208 print_graph_proc(struct trace_seq *s, pid_t pid)
 209 {
 210         char comm[TASK_COMM_LEN];
 211         /* sign + log10(MAX_INT) + '\0' */
 212         char pid_str[11];
 213         int spaces = 0;
 214         int ret;
 215         int len;
 216         int i;
 217
 218         trace_find_cmdline(pid, comm);
 219         comm[7] = '\0';
 220         sprintf(pid_str, "%d", pid);
 221
 222         /* 1 stands for the "-" character */
 223         len = strlen(comm) + strlen(pid_str) + 1;
 224
 225         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
 226                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
 227
 228         /* First spaces to align center */
 229         for (i = 0; i < spaces / 2; i++) {
 230                 ret = trace_seq_printf(s, " ");
 231                 if (!ret)
 232                         return TRACE_TYPE_PARTIAL_LINE;
 233         }
 234
 235         ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
 236         if (!ret)
 237                 return TRACE_TYPE_PARTIAL_LINE;
 238
 239         /* Last spaces to align center */
 240         for (i = 0; i < spaces - (spaces / 2); i++) {
 241                 ret = trace_seq_printf(s, " ");
 242                 if (!ret)
 243                         return TRACE_TYPE_PARTIAL_LINE;
 244         }
 245         return TRACE_TYPE_HANDLED;
 246 }
 247
 248
 249 /* If the pid changed since the last trace, output this event */
 250 static enum print_line_t
 251 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
 252 {
 253         pid_t prev_pid;
 254         pid_t *last_pid;
 255         int ret;
 256
 257         if (!data)
 258                 return TRACE_TYPE_HANDLED;
 259
 260         last_pid = &(per_cpu_ptr(data, cpu)->last_pid);
 261
 262         if (*last_pid == pid)
 263                 return TRACE_TYPE_HANDLED;
 264
 265         prev_pid = *last_pid;
 266         *last_pid = pid;
 267
 268         if (prev_pid == -1)
 269                 return TRACE_TYPE_HANDLED;
 270 /*
 271  * Context-switch trace line:
 272
 273  ------------------------------------------
 274  | 1)  migration/0--1  =>  sshd-1755
 275  ------------------------------------------
 276
 277  */
 278         ret = trace_seq_printf(s,
 279                 " ------------------------------------------\n");
 280         if (!ret)
 281                 return TRACE_TYPE_PARTIAL_LINE;
 282
 283         ret = print_graph_cpu(s, cpu);
 284         if (ret == TRACE_TYPE_PARTIAL_LINE)
 285                 return TRACE_TYPE_PARTIAL_LINE;
 286
 287         ret = print_graph_proc(s, prev_pid);
 288         if (ret == TRACE_TYPE_PARTIAL_LINE)
 289                 return TRACE_TYPE_PARTIAL_LINE;
 290
 291         ret = trace_seq_printf(s, " => ");
 292         if (!ret)
 293                 return TRACE_TYPE_PARTIAL_LINE;
 294
 295         ret = print_graph_proc(s, pid);
 296         if (ret == TRACE_TYPE_PARTIAL_LINE)
 297                 return TRACE_TYPE_PARTIAL_LINE;
 298
 299         ret = trace_seq_printf(s,
 300                 "\n ------------------------------------------\n\n");
 301         if (!ret)
 302                 return TRACE_TYPE_PARTIAL_LINE;
 303
 304         return TRACE_TYPE_HANDLED;
 305 }
 306
 307 static struct ftrace_graph_ret_entry *
 308 get_return_for_leaf(struct trace_iterator *iter,
 309                 struct ftrace_graph_ent_entry *curr)
 310 {
 311         struct ring_buffer_iter *ring_iter;
 312         struct ring_buffer_event *event;
 313         struct ftrace_graph_ret_entry *next;
 314
 315         ring_iter = iter->buffer_iter[iter->cpu];
 316
 317         /* First peek to compare current entry and the next one */
 318         if (ring_iter)
 319                 event = ring_buffer_iter_peek(ring_iter, NULL);
 320         else {
 321         /* We need to consume the current entry to see the next one */
 322                 ring_buffer_consume(iter->tr->buffer, iter->cpu, NULL);
 323                 event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
 324                                         NULL);
 325         }
 326
 327         if (!event)
 328                 return NULL;
 329
 330         next = ring_buffer_event_data(event);
 331
 332         if (next->ent.type != TRACE_GRAPH_RET)
 333                 return NULL;
 334
 335         if (curr->ent.pid != next->ent.pid ||
 336                         curr->graph_ent.func != next->ret.func)
 337                 return NULL;
 338
 339         /* this is a leaf, now advance the iterator */
 340         if (ring_iter)
 341                 ring_buffer_read(ring_iter, NULL);
 342
 343         return next;
 344 }
 345
 346 /* Signal a overhead of time execution to the output */
 347 static int
 348 print_graph_overhead(unsigned long long duration, struct trace_seq *s)
 349 {
 350         /* If duration disappear, we don't need anything */
 351         if (!(tracer_flags.val & TRACE_GRAPH_PRINT_DURATION))
 352                 return 1;
 353
 354         /* Non nested entry or return */
 355         if (duration == -1)
 356                 return trace_seq_printf(s, "  ");
 357
 358         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
 359                 /* Duration exceeded 100 msecs */
 360                 if (duration > 100000ULL)
 361                         return trace_seq_printf(s, "! ");
 362
 363                 /* Duration exceeded 10 msecs */
 364                 if (duration > 10000ULL)
 365                         return trace_seq_printf(s, "+ ");
 366         }
 367
 368         return trace_seq_printf(s, "  ");
 369 }
 370
 371 static int print_graph_abs_time(u64 t, struct trace_seq *s)
 372 {
 373         unsigned long usecs_rem;
 374
 375         usecs_rem = do_div(t, NSEC_PER_SEC);
 376         usecs_rem /= 1000;
 377
 378         return trace_seq_printf(s, "%5lu.%06lu |  ",
 379                         (unsigned long)t, usecs_rem);
 380 }
 381
 382 static enum print_line_t
 383 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 384                 enum trace_type type, int cpu, pid_t pid)
 385 {
 386         int ret;
 387         struct trace_seq *s = &iter->seq;
 388
 389         if (addr < (unsigned long)__irqentry_text_start ||
 390                 addr >= (unsigned long)__irqentry_text_end)
 391                 return TRACE_TYPE_UNHANDLED;
 392
 393         /* Absolute time */
 394         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
 395                 ret = print_graph_abs_time(iter->ts, s);
 396                 if (!ret)
 397                         return TRACE_TYPE_PARTIAL_LINE;
 398         }
 399
 400         /* Cpu */
 401         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 402                 ret = print_graph_cpu(s, cpu);
 403                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 404                         return TRACE_TYPE_PARTIAL_LINE;
 405         }
 406         /* Proc */
 407         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 408                 ret = print_graph_proc(s, pid);
 409                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 410                         return TRACE_TYPE_PARTIAL_LINE;
 411                 ret = trace_seq_printf(s, " | ");
 412                 if (!ret)
 413                         return TRACE_TYPE_PARTIAL_LINE;
 414         }
 415
 416         /* No overhead */
 417         ret = print_graph_overhead(-1, s);
 418         if (!ret)
 419                 return TRACE_TYPE_PARTIAL_LINE;
 420
 421         if (type == TRACE_GRAPH_ENT)
 422                 ret = trace_seq_printf(s, "==========>");
 423         else
 424                 ret = trace_seq_printf(s, "<==========");
 425
 426         if (!ret)
 427                 return TRACE_TYPE_PARTIAL_LINE;
 428
 429         /* Don't close the duration column if haven't one */
 430         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 431                 trace_seq_printf(s, " |");
 432         ret = trace_seq_printf(s, "\n");
 433
 434         if (!ret)
 435                 return TRACE_TYPE_PARTIAL_LINE;
 436         return TRACE_TYPE_HANDLED;
 437 }
 438
 439 enum print_line_t
 440 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 441 {
 442         unsigned long nsecs_rem = do_div(duration, 1000);
 443         /* log10(ULONG_MAX) + '\0' */
 444         char msecs_str[21];
 445         char nsecs_str[5];
 446         int ret, len;
 447         int i;
 448
 449         sprintf(msecs_str, "%lu", (unsigned long) duration);
 450
 451         /* Print msecs */
 452         ret = trace_seq_printf(s, "%s", msecs_str);
 453         if (!ret)
 454                 return TRACE_TYPE_PARTIAL_LINE;
 455
 456         len = strlen(msecs_str);
 457
 458         /* Print nsecs (we don't want to exceed 7 numbers) */
 459         if (len < 7) {
 460                 snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
 461                 ret = trace_seq_printf(s, ".%s", nsecs_str);
 462                 if (!ret)
 463                         return TRACE_TYPE_PARTIAL_LINE;
 464                 len += strlen(nsecs_str);
 465         }
 466
 467         ret = trace_seq_printf(s, " us ");
 468         if (!ret)
 469                 return TRACE_TYPE_PARTIAL_LINE;
 470
 471         /* Print remaining spaces to fit the row's width */
 472         for (i = len; i < 7; i++) {
 473                 ret = trace_seq_printf(s, " ");
 474                 if (!ret)
 475                         return TRACE_TYPE_PARTIAL_LINE;
 476         }
 477         return TRACE_TYPE_HANDLED;
 478 }
 479
 480 static enum print_line_t
 481 print_graph_duration(unsigned long long duration, struct trace_seq *s)
 482 {
 483         int ret;
 484
 485         ret = trace_print_graph_duration(duration, s);
 486         if (ret != TRACE_TYPE_HANDLED)
 487                 return ret;
 488
 489         ret = trace_seq_printf(s, "|  ");
 490         if (!ret)
 491                 return TRACE_TYPE_PARTIAL_LINE;
 492
 493         return TRACE_TYPE_HANDLED;
 494 }
 495
 496 /* Case of a leaf function on its call entry */
 497 static enum print_line_t
 498 print_graph_entry_leaf(struct trace_iterator *iter,
 499                 struct ftrace_graph_ent_entry *entry,
 500                 struct ftrace_graph_ret_entry *ret_entry, struct trace_seq *s)
 501 {
 502         struct fgraph_data *data = iter->private;
 503         struct ftrace_graph_ret *graph_ret;
 504         struct ftrace_graph_ent *call;
 505         unsigned long long duration;
 506         int ret;
 507         int i;
 508
 509         graph_ret = &ret_entry->ret;
 510         call = &entry->graph_ent;
 511         duration = graph_ret->rettime - graph_ret->calltime;
 512
 513         if (data) {
 514                 int cpu = iter->cpu;
 515                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 516
 517                 /*
 518                  * Comments display at + 1 to depth. Since
 519                  * this is a leaf function, keep the comments
 520                  * equal to this depth.
 521                  */
 522                 *depth = call->depth - 1;
 523         }
 524
 525         /* Overhead */
 526         ret = print_graph_overhead(duration, s);
 527         if (!ret)
 528                 return TRACE_TYPE_PARTIAL_LINE;
 529
 530         /* Duration */
 531         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 532                 ret = print_graph_duration(duration, s);
 533                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 534                         return TRACE_TYPE_PARTIAL_LINE;
 535         }
 536
 537         /* Function */
 538         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 539                 ret = trace_seq_printf(s, " ");
 540                 if (!ret)
 541                         return TRACE_TYPE_PARTIAL_LINE;
 542         }
 543
 544         ret = trace_seq_printf(s, "%pf();\n", (void *)call->func);
 545         if (!ret)
 546                 return TRACE_TYPE_PARTIAL_LINE;
 547
 548         return TRACE_TYPE_HANDLED;
 549 }
 550
 551 static enum print_line_t
 552 print_graph_entry_nested(struct trace_iterator *iter,
 553                          struct ftrace_graph_ent_entry *entry,
 554                          struct trace_seq *s, int cpu)
 555 {
 556         struct ftrace_graph_ent *call = &entry->graph_ent;
 557         struct fgraph_data *data = iter->private;
 558         int ret;
 559         int i;
 560
 561         if (data) {
 562                 int cpu = iter->cpu;
 563                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 564
 565                 *depth = call->depth;
 566         }
 567
 568         /* No overhead */
 569         ret = print_graph_overhead(-1, s);
 570         if (!ret)
 571                 return TRACE_TYPE_PARTIAL_LINE;
 572
 573         /* No time */
 574         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 575                 ret = trace_seq_printf(s, "            |  ");
 576                 if (!ret)
 577                         return TRACE_TYPE_PARTIAL_LINE;
 578         }
 579
 580         /* Function */
 581         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 582                 ret = trace_seq_printf(s, " ");
 583                 if (!ret)
 584                         return TRACE_TYPE_PARTIAL_LINE;
 585         }
 586
 587         ret = trace_seq_printf(s, "%pf() {\n", (void *)call->func);
 588         if (!ret)
 589                 return TRACE_TYPE_PARTIAL_LINE;
 590
 591         /*
 592          * we already consumed the current entry to check the next one
 593          * and see if this is a leaf.
 594          */
 595         return TRACE_TYPE_NO_CONSUME;
 596 }
 597
 598 static enum print_line_t
 599 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
 600                      int type, unsigned long addr)
 601 {
 602         struct fgraph_data *data = iter->private;
 603         struct trace_entry *ent = iter->ent;
 604         int cpu = iter->cpu;
 605         int ret;
 606
 607         /* Pid */
 608         if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
 609                 return TRACE_TYPE_PARTIAL_LINE;
 610
 611         if (type) {
 612                 /* Interrupt */
 613                 ret = print_graph_irq(iter, addr, type, cpu, ent->pid);
 614                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 615                         return TRACE_TYPE_PARTIAL_LINE;
 616         }
 617
 618         /* Absolute time */
 619         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
 620                 ret = print_graph_abs_time(iter->ts, s);
 621                 if (!ret)
 622                         return TRACE_TYPE_PARTIAL_LINE;
 623         }
 624
 625         /* Cpu */
 626         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
 627                 ret = print_graph_cpu(s, cpu);
 628                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 629                         return TRACE_TYPE_PARTIAL_LINE;
 630         }
 631
 632         /* Proc */
 633         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
 634                 ret = print_graph_proc(s, ent->pid);
 635                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 636                         return TRACE_TYPE_PARTIAL_LINE;
 637
 638                 ret = trace_seq_printf(s, " | ");
 639                 if (!ret)
 640                         return TRACE_TYPE_PARTIAL_LINE;
 641         }
 642
 643         return 0;
 644 }
 645
 646 static enum print_line_t
 647 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
 648                         struct trace_iterator *iter)
 649 {
 650         int cpu = iter->cpu;
 651         struct ftrace_graph_ent *call = &field->graph_ent;
 652         struct ftrace_graph_ret_entry *leaf_ret;
 653
 654         if (print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func))
 655                 return TRACE_TYPE_PARTIAL_LINE;
 656
 657         leaf_ret = get_return_for_leaf(iter, field);
 658         if (leaf_ret)
 659                 return print_graph_entry_leaf(iter, field, leaf_ret, s);
 660         else
 661                 return print_graph_entry_nested(iter, field, s, cpu);
 662
 663 }
 664
 665 static enum print_line_t
 666 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 667                    struct trace_entry *ent, struct trace_iterator *iter)
 668 {
 669         unsigned long long duration = trace->rettime - trace->calltime;
 670         struct fgraph_data *data = iter->private;
 671         pid_t pid = ent->pid;
 672         int cpu = iter->cpu;
 673         int ret;
 674         int i;
 675
 676         if (data) {
 677                 int cpu = iter->cpu;
 678                 int *depth = &(per_cpu_ptr(data, cpu)->depth);
 679
 680                 /*
 681                  * Comments display at + 1 to depth. This is the
 682                  * return from a function, we now want the comments
 683                  * to display at the same level of the bracket.
 684                  */
 685                 *depth = trace->depth - 1;
 686         }
 687
 688         if (print_graph_prologue(iter, s, 0, 0))
 689                 return TRACE_TYPE_PARTIAL_LINE;
 690
 691         /* Overhead */
 692         ret = print_graph_overhead(duration, s);
 693         if (!ret)
 694                 return TRACE_TYPE_PARTIAL_LINE;
 695
 696         /* Duration */
 697         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 698                 ret = print_graph_duration(duration, s);
 699                 if (ret == TRACE_TYPE_PARTIAL_LINE)
 700                         return TRACE_TYPE_PARTIAL_LINE;
 701         }
 702
 703         /* Closing brace */
 704         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
 705                 ret = trace_seq_printf(s, " ");
 706                 if (!ret)
 707                         return TRACE_TYPE_PARTIAL_LINE;
 708         }
 709
 710         ret = trace_seq_printf(s, "}\n");
 711         if (!ret)
 712                 return TRACE_TYPE_PARTIAL_LINE;
 713
 714         /* Overrun */
 715         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
 716                 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
 717                                         trace->overrun);
 718                 if (!ret)
 719                         return TRACE_TYPE_PARTIAL_LINE;
 720         }
 721
 722         ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET, cpu, pid);
 723         if (ret == TRACE_TYPE_PARTIAL_LINE)
 724                 return TRACE_TYPE_PARTIAL_LINE;
 725
 726         return TRACE_TYPE_HANDLED;
 727 }
 728
 729 static enum print_line_t
 730 print_graph_comment(struct trace_seq *s,  struct trace_entry *ent,
 731                     struct trace_iterator *iter)
 732 {
 733         unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
 734         struct fgraph_data *data = iter->private;
 735         struct trace_event *event;
 736         int depth = 0;
 737         int ret;
 738         int i;
 739
 740         if (data)
 741                 depth = per_cpu_ptr(data, iter->cpu)->depth;
 742
 743         if (print_graph_prologue(iter, s, 0, 0))
 744                 return TRACE_TYPE_PARTIAL_LINE;
 745
 746         /* No overhead */
 747         ret = print_graph_overhead(-1, s);
 748         if (!ret)
 749                 return TRACE_TYPE_PARTIAL_LINE;
 750
 751         /* No time */
 752         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
 753                 ret = trace_seq_printf(s, "            |  ");
 754                 if (!ret)
 755                         return TRACE_TYPE_PARTIAL_LINE;
 756         }
 757
 758         /* Indentation */
 759         if (depth > 0)
 760                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
 761                         ret = trace_seq_printf(s, " ");
 762                         if (!ret)
 763                                 return TRACE_TYPE_PARTIAL_LINE;
 764                 }
 765
 766         /* The comment */
 767         ret = trace_seq_printf(s, "/* ");
 768         if (!ret)
 769                 return TRACE_TYPE_PARTIAL_LINE;
 770
 771         switch (iter->ent->type) {
 772         case TRACE_BPRINT:
 773                 ret = trace_print_bprintk_msg_only(iter);
 774                 if (ret != TRACE_TYPE_HANDLED)
 775                         return ret;
 776                 break;
 777         case TRACE_PRINT:
 778                 ret = trace_print_printk_msg_only(iter);
 779                 if (ret != TRACE_TYPE_HANDLED)
 780                         return ret;
 781                 break;
 782         default:
 783                 event = ftrace_find_event(ent->type);
 784                 if (!event)
 785                         return TRACE_TYPE_UNHANDLED;
 786
 787                 ret = event->trace(iter, sym_flags);
 788                 if (ret != TRACE_TYPE_HANDLED)
 789                         return ret;
 790         }
 791
 792         /* Strip ending newline */
 793         if (s->buffer[s->len - 1] == '\n') {
 794                 s->buffer[s->len - 1] = '\0';
 795                 s->len--;
 796         }
 797
 798         ret = trace_seq_printf(s, " */\n");
 799         if (!ret)
 800                 return TRACE_TYPE_PARTIAL_LINE;
 801
 802         return TRACE_TYPE_HANDLED;
 803 }
 804
 805
 806 enum print_line_t
 807 print_graph_function(struct trace_iterator *iter)
 808 {
 809         struct trace_entry *entry = iter->ent;
 810         struct trace_seq *s = &iter->seq;
 811
 812         switch (entry->type) {
 813         case TRACE_GRAPH_ENT: {
 814                 struct ftrace_graph_ent_entry *field;
 815                 trace_assign_type(field, entry);
 816                 return print_graph_entry(field, s, iter);
 817         }
 818         case TRACE_GRAPH_RET: {
 819                 struct ftrace_graph_ret_entry *field;
 820                 trace_assign_type(field, entry);
 821                 return print_graph_return(&field->ret, s, entry, iter);
 822         }
 823         default:
 824                 return print_graph_comment(s, entry, iter);
 825         }
 826
 827         return TRACE_TYPE_HANDLED;
 828 }
 829
 830 static void print_graph_headers(struct seq_file *s)
 831 {
 832         /* 1st line */
 833         seq_printf(s, "# ");
 834         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
 835                 seq_printf(s, "     TIME       ");
 836         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 837                 seq_printf(s, "CPU");
 838         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 839                 seq_printf(s, "  TASK/PID      ");
 840         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 841                 seq_printf(s, "  DURATION   ");
 842         seq_printf(s, "               FUNCTION CALLS\n");
 843
 844         /* 2nd line */
 845         seq_printf(s, "# ");
 846         if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
 847                 seq_printf(s, "      |         ");
 848         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
 849                 seq_printf(s, "|  ");
 850         if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
 851                 seq_printf(s, "  |    |        ");
 852         if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
 853                 seq_printf(s, "   |   |      ");
 854         seq_printf(s, "               |   |   |   |\n");
 855 }
 856
 857 static void graph_trace_open(struct trace_iterator *iter)
 858 {
 859         /* pid and depth on the last trace processed */
 860         struct fgraph_data *data = alloc_percpu(struct fgraph_data);
 861         int cpu;
 862
 863         if (!data)
 864                 pr_warning("function graph tracer: not enough memory\n");
 865         else
 866                 for_each_possible_cpu(cpu) {
 867                         pid_t *pid = &(per_cpu_ptr(data, cpu)->last_pid);
 868                         int *depth = &(per_cpu_ptr(data, cpu)->depth);
 869                         *pid = -1;
 870                         *depth = 0;
 871                 }
 872
 873         iter->private = data;
 874 }
 875
 876 static void graph_trace_close(struct trace_iterator *iter)
 877 {
 878         free_percpu(iter->private);
 879 }
 880
 881 static struct tracer graph_trace __read_mostly = {
 882         .name           = "function_graph",
 883         .open           = graph_trace_open,
 884         .close          = graph_trace_close,
 885         .wait_pipe      = poll_wait_pipe,
 886         .init           = graph_trace_init,
 887         .reset          = graph_trace_reset,
 888         .print_line     = print_graph_function,
 889         .print_header   = print_graph_headers,
 890         .flags          = &tracer_flags,
 891 #ifdef CONFIG_FTRACE_SELFTEST
 892         .selftest       = trace_selftest_startup_function_graph,
 893 #endif
 894 };
 895
 896 static __init int init_graph_trace(void)
 897 {
 898         max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);
 899
 900         return register_tracer(&graph_trace);
 901 }
 902
 903 device_initcall(init_graph_trace);