kernel/trace/trace_functions_graph.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *
   4  * Function graph tracer.
   5  * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
   6  * Mostly borrowed from function tracer which
   7  * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
   8  *
   9  */
  10 #include <linux/uaccess.h>
  11 #include <linux/ftrace.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/slab.h>
  14 #include <linux/fs.h>
  15
  16 #include "trace.h"
  17 #include "trace_output.h"
  18
  19 static bool kill_ftrace_graph;
  20
  21 /**
  22  * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called
  23  *
  24  * ftrace_graph_stop() is called when a severe error is detected in
  25  * the function graph tracing. This function is called by the critical
  26  * paths of function graph to keep those paths from doing any more harm.
  27  */
  28 bool ftrace_graph_is_dead(void)
  29 {
  30         return kill_ftrace_graph;
  31 }
  32
  33 /**
  34  * ftrace_graph_stop - set to permanently disable function graph tracincg
  35  *
  36  * In case of an error int function graph tracing, this is called
  37  * to try to keep function graph tracing from causing any more harm.
  38  * Usually this is pretty severe and this is called to try to at least
  39  * get a warning out to the user.
  40  */
  41 void ftrace_graph_stop(void)
  42 {
  43         kill_ftrace_graph = true;
  44 }
  45
  46 /* When set, irq functions will be ignored */
  47 static int ftrace_graph_skip_irqs;
  48
  49 struct fgraph_cpu_data {
  50         pid_t           last_pid;
  51         int             depth;
  52         int             depth_irq;
  53         int             ignore;
  54         unsigned long   enter_funcs[FTRACE_RETFUNC_DEPTH];
  55 };
  56
  57 struct fgraph_data {
  58         struct fgraph_cpu_data __percpu *cpu_data;
  59
  60         /* Place to preserve last processed entry. */
  61         struct ftrace_graph_ent_entry   ent;
  62         struct ftrace_graph_ret_entry   ret;
  63         int                             failed;
  64         int                             cpu;
  65 };
  66
  67 #define TRACE_GRAPH_INDENT      2
  68
  69 unsigned int fgraph_max_depth;
  70
  71 static struct tracer_opt trace_opts[] = {
  72         /* Display overruns? (for self-debug purpose) */
  73         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
  74         /* Display CPU ? */
  75         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
  76         /* Display Overhead ? */
  77         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
  78         /* Display proc name/pid */
  79         { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
  80         /* Display duration of execution */
  81         { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
  82         /* Display absolute time of an entry */
  83         { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
  84         /* Display interrupts */
  85         { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
  86         /* Display function name after trailing } */
  87         { TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) },
  88         /* Include sleep time (scheduled out) between entry and return */
  89         { TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },
  90         /* Include time within nested functions */
  91         { TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) },
  92         { } /* Empty entry */
  93 };
  94
  95 static struct tracer_flags tracer_flags = {
  96         /* Don't display overruns, proc, or tail by default */
  97         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
  98                TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS |
  99                TRACE_GRAPH_SLEEP_TIME | TRACE_GRAPH_GRAPH_TIME,
 100         .opts = trace_opts
 101 };
 102
 103 static struct trace_array *graph_array;
 104
 105 /*
 106  * DURATION column is being also used to display IRQ signs,
 107  * following values are used by print_graph_irq and others
 108  * to fill in space into DURATION column.
 109  */
 110 enum {
 111         FLAGS_FILL_FULL  = 1 << TRACE_GRAPH_PRINT_FILL_SHIFT,
 112         FLAGS_FILL_START = 2 << TRACE_GRAPH_PRINT_FILL_SHIFT,
 113         FLAGS_FILL_END   = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT,
 114 };
 115
 116 static void
 117 print_graph_duration(struct trace_array *tr, unsigned long long duration,
 118                      struct trace_seq *s, u32 flags);
 119
 120 /* Add a function return address to the trace stack on thread info.*/
 121 int
 122 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
 123                          unsigned long frame_pointer, unsigned long *retp)
 124 {
 125         unsigned long long calltime;
 126         int index;
 127
 128         if (unlikely(ftrace_graph_is_dead()))
 129                 return -EBUSY;
 130
 131         if (!current->ret_stack)
 132                 return -EBUSY;
 133
 134         /*
 135          * We must make sure the ret_stack is tested before we read
 136          * anything else.
 137          */
 138         smp_rmb();
 139
 140         /* The return trace stack is full */
 141         if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
 142                 atomic_inc(&current->trace_overrun);
 143                 return -EBUSY;
 144         }
 145
 146         /*
 147          * The curr_ret_stack is an index to ftrace return stack of
 148          * current task.  Its value should be in [0, FTRACE_RETFUNC_
 149          * DEPTH) when the function graph tracer is used.  To support
 150          * filtering out specific functions, it makes the index
 151          * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
 152          * so when it sees a negative index the ftrace will ignore
 153          * the record.  And the index gets recovered when returning
 154          * from the filtered function by adding the FTRACE_NOTRACE_
 155          * DEPTH and then it'll continue to record functions normally.
 156          *
 157          * The curr_ret_stack is initialized to -1 and get increased
 158          * in this function.  So it can be less than -1 only if it was
 159          * filtered out via ftrace_graph_notrace_addr() which can be
 160          * set from set_graph_notrace file in tracefs by user.
 161          */
 162         if (current->curr_ret_stack < -1)
 163                 return -EBUSY;
 164
 165         calltime = trace_clock_local();
 166
 167         index = ++current->curr_ret_stack;
 168         if (ftrace_graph_notrace_addr(func))
 169                 current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
 170         barrier();
 171         current->ret_stack[index].ret = ret;
 172         current->ret_stack[index].func = func;
 173         current->ret_stack[index].calltime = calltime;
 174 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
 175         current->ret_stack[index].fp = frame_pointer;
 176 #endif
 177 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 178         current->ret_stack[index].retp = retp;
 179 #endif
 180         *depth = current->curr_ret_stack;
 181
 182         return 0;
 183 }
 184
 185 /* Retrieve a function return address to the trace stack on thread info.*/
 186 static void
 187 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
 188                         unsigned long frame_pointer)
 189 {
 190         int index;
 191
 192         index = current->curr_ret_stack;
 193
 194         /*
 195          * A negative index here means that it's just returned from a
 196          * notrace'd function.  Recover index to get an original
 197          * return address.  See ftrace_push_return_trace().
 198          *
 199          * TODO: Need to check whether the stack gets corrupted.
 200          */
 201         if (index < 0)
 202                 index += FTRACE_NOTRACE_DEPTH;
 203
 204         if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
 205                 ftrace_graph_stop();
 206                 WARN_ON(1);
 207                 /* Might as well panic, otherwise we have no where to go */
 208                 *ret = (unsigned long)panic;
 209                 return;
 210         }
 211
 212 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
 213         /*
 214          * The arch may choose to record the frame pointer used
 215          * and check it here to make sure that it is what we expect it
 216          * to be. If gcc does not set the place holder of the return
 217          * address in the frame pointer, and does a copy instead, then
 218          * the function graph trace will fail. This test detects this
 219          * case.
 220          *
 221          * Currently, x86_32 with optimize for size (-Os) makes the latest
 222          * gcc do the above.
 223          *
 224          * Note, -mfentry does not use frame pointers, and this test
 225          *  is not needed if CC_USING_FENTRY is set.
 226          */
 227         if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
 228                 ftrace_graph_stop();
 229                 WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
 230                      "  from func %ps return to %lx\n",
 231                      current->ret_stack[index].fp,
 232                      frame_pointer,
 233                      (void *)current->ret_stack[index].func,
 234                      current->ret_stack[index].ret);
 235                 *ret = (unsigned long)panic;
 236                 return;
 237         }
 238 #endif
 239
 240         *ret = current->ret_stack[index].ret;
 241         trace->func = current->ret_stack[index].func;
 242         trace->calltime = current->ret_stack[index].calltime;
 243         trace->overrun = atomic_read(&current->trace_overrun);
 244         trace->depth = index;
 245 }
 246
 247 /*
 248  * Send the trace to the ring-buffer.
 249  * @return the original return address.
 250  */
 251 unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
 252 {
 253         struct ftrace_graph_ret trace;
 254         unsigned long ret;
 255
 256         ftrace_pop_return_trace(&trace, &ret, frame_pointer);
 257         trace.rettime = trace_clock_local();
 258         barrier();
 259         current->curr_ret_stack--;
 260         /*
 261          * The curr_ret_stack can be less than -1 only if it was
 262          * filtered out and it's about to return from the function.
 263          * Recover the index and continue to trace normal functions.
 264          */
 265         if (current->curr_ret_stack < -1) {
 266                 current->curr_ret_stack += FTRACE_NOTRACE_DEPTH;
 267                 return ret;
 268         }
 269
 270         /*
 271          * The trace should run after decrementing the ret counter
 272          * in case an interrupt were to come in. We don't want to
 273          * lose the interrupt if max_depth is set.
 274          */
 275         ftrace_graph_return(&trace);
 276
 277         if (unlikely(!ret)) {
 278                 ftrace_graph_stop();
 279                 WARN_ON(1);
 280                 /* Might as well panic. What else to do? */
 281                 ret = (unsigned long)panic;
 282         }
 283
 284         return ret;
 285 }
 286
 287 /**
 288  * ftrace_graph_ret_addr - convert a potentially modified stack return address
 289  *                         to its original value
 290  *
 291  * This function can be called by stack unwinding code to convert a found stack
 292  * return address ('ret') to its original value, in case the function graph
 293  * tracer has modified it to be 'return_to_handler'.  If the address hasn't
 294  * been modified, the unchanged value of 'ret' is returned.
 295  *
 296  * 'idx' is a state variable which should be initialized by the caller to zero
 297  * before the first call.
 298  *
 299  * 'retp' is a pointer to the return address on the stack.  It's ignored if
 300  * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
 301  */
 302 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 303 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
 304                                     unsigned long ret, unsigned long *retp)
 305 {
 306         int index = task->curr_ret_stack;
 307         int i;
 308
 309         if (ret != (unsigned long)return_to_handler)
 310                 return ret;
 311
 312         if (index < -1)
 313                 index += FTRACE_NOTRACE_DEPTH;
 314
 315         if (index < 0)
 316                 return ret;
 317
 318         for (i = 0; i <= index; i++)
 319                 if (task->ret_stack[i].retp == retp)
 320                         return task->ret_stack[i].ret;
 321
 322         return ret;
 323 }
 324 #else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
 325 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
 326                                     unsigned long ret, unsigned long *retp)
 327 {
 328         int task_idx;
 329
 330         if (ret != (unsigned long)return_to_handler)
 331                 return ret;
 332
 333         task_idx = task->curr_ret_stack;
 334
 335         if (!task->ret_stack || task_idx < *idx)
 336                 return ret;
 337
 338         task_idx -= *idx;
 339         (*idx)++;
 340
 341         return task->ret_stack[task_idx].ret;
 342 }
 343 #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
 344
 345 int __trace_graph_entry(struct trace_array *tr,
 346                                 struct ftrace_graph_ent *trace,
 347                                 unsigned long flags,
 348                                 int pc)
 349 {
 350         struct trace_event_call *call = &event_funcgraph_entry;
 351         struct ring_buffer_event *event;
 352         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 353         struct ftrace_graph_ent_entry *entry;
 354
 355         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
 356                                           sizeof(*entry), flags, pc);
 357         if (!event)
 358                 return 0;
 359         entry   = ring_buffer_event_data(event);
 360         entry->graph_ent                        = *trace;
 361         if (!call_filter_check_discard(call, entry, buffer, event))
 362                 trace_buffer_unlock_commit_nostack(buffer, event);
 363
 364         return 1;
 365 }
 366
 367 static inline int ftrace_graph_ignore_irqs(void)
 368 {
 369         if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
 370                 return 0;
 371
 372         return in_irq();
 373 }
 374
 375 int trace_graph_entry(struct ftrace_graph_ent *trace)
 376 {
 377         struct trace_array *tr = graph_array;
 378         struct trace_array_cpu *data;
 379         unsigned long flags;
 380         long disabled;
 381         int ret;
 382         int cpu;
 383         int pc;
 384
 385         if (!ftrace_trace_task(tr))
 386                 return 0;
 387
 388         if (ftrace_graph_ignore_func(trace))
 389                 return 0;
 390
 391         if (ftrace_graph_ignore_irqs())
 392                 return 0;
 393
 394         /*
 395          * Do not trace a function if it's filtered by set_graph_notrace.
 396          * Make the index of ret stack negative to indicate that it should
 397          * ignore further functions.  But it needs its own ret stack entry
 398          * to recover the original index in order to continue tracing after
 399          * returning from the function.
 400          */
 401         if (ftrace_graph_notrace_addr(trace->func))
 402                 return 1;
 403
 404         /*
 405          * Stop here if tracing_threshold is set. We only write function return
 406          * events to the ring buffer.
 407          */
 408         if (tracing_thresh)
 409                 return 1;
 410
 411         local_irq_save(flags);
 412         cpu = raw_smp_processor_id();
 413         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 414         disabled = atomic_inc_return(&data->disabled);
 415         if (likely(disabled == 1)) {
 416                 pc = preempt_count();
 417                 ret = __trace_graph_entry(tr, trace, flags, pc);
 418         } else {
 419                 ret = 0;
 420         }
 421
 422         atomic_dec(&data->disabled);
 423         local_irq_restore(flags);
 424
 425         return ret;
 426 }
 427
 428 static void
 429 __trace_graph_function(struct trace_array *tr,
 430                 unsigned long ip, unsigned long flags, int pc)
 431 {
 432         u64 time = trace_clock_local();
 433         struct ftrace_graph_ent ent = {
 434                 .func  = ip,
 435                 .depth = 0,
 436         };
 437         struct ftrace_graph_ret ret = {
 438                 .func     = ip,
 439                 .depth    = 0,
 440                 .calltime = time,
 441                 .rettime  = time,
 442         };
 443
 444         __trace_graph_entry(tr, &ent, flags, pc);
 445         __trace_graph_return(tr, &ret, flags, pc);
 446 }
 447
 448 void
 449 trace_graph_function(struct trace_array *tr,
 450                 unsigned long ip, unsigned long parent_ip,
 451                 unsigned long flags, int pc)
 452 {
 453         __trace_graph_function(tr, ip, flags, pc);
 454 }
 455
 456 void __trace_graph_return(struct trace_array *tr,
 457                                 struct ftrace_graph_ret *trace,
 458                                 unsigned long flags,
 459                                 int pc)
 460 {
 461         struct trace_event_call *call = &event_funcgraph_exit;
 462         struct ring_buffer_event *event;
 463         struct ring_buffer *buffer = tr->trace_buffer.buffer;
 464         struct ftrace_graph_ret_entry *entry;
 465
 466         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
 467                                           sizeof(*entry), flags, pc);
 468         if (!event)
 469                 return;
 470         entry   = ring_buffer_event_data(event);
 471         entry->ret                              = *trace;
 472         if (!call_filter_check_discard(call, entry, buffer, event))
 473                 trace_buffer_unlock_commit_nostack(buffer, event);
 474 }
 475
 476 void trace_graph_return(struct ftrace_graph_ret *trace)
 477 {
 478         struct trace_array *tr = graph_array;
 479         struct trace_array_cpu *data;
 480         unsigned long flags;
 481         long disabled;
 482         int cpu;
 483         int pc;
 484
 485         local_irq_save(flags);
 486         cpu = raw_smp_processor_id();
 487         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 488         disabled = atomic_inc_return(&data->disabled);
 489         if (likely(disabled == 1)) {
 490                 pc = preempt_count();
 491                 __trace_graph_return(tr, trace, flags, pc);
 492         }
 493         atomic_dec(&data->disabled);
 494         local_irq_restore(flags);
 495 }
 496
 497 void set_graph_array(struct trace_array *tr)
 498 {
 499         graph_array = tr;
 500
 501         /* Make graph_array visible before we start tracing */
 502
 503         smp_mb();
 504 }
 505
 506 static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
 507 {
 508         if (tracing_thresh &&
 509             (trace->rettime - trace->calltime < tracing_thresh))
 510                 return;
 511         else
 512                 trace_graph_return(trace);
 513 }
 514
 515 static int graph_trace_init(struct trace_array *tr)
 516 {
 517         int ret;
 518
 519         set_graph_array(tr);
 520         if (tracing_thresh)
 521                 ret = register_ftrace_graph(&trace_graph_thresh_return,
 522                                             &trace_graph_entry);
 523         else
 524                 ret = register_ftrace_graph(&trace_graph_return,
 525                                             &trace_graph_entry);
 526         if (ret)
 527                 return ret;
 528         tracing_start_cmdline_record();
 529
 530         return 0;
 531 }
 532
 533 static void graph_trace_reset(struct trace_array *tr)
 534 {
 535         tracing_stop_cmdline_record();
 536         unregister_ftrace_graph();
 537 }
 538
 539 static int graph_trace_update_thresh(struct trace_array *tr)
 540 {
 541         graph_trace_reset(tr);
 542         return graph_trace_init(tr);
 543 }
 544
 545 static int max_bytes_for_cpu;
 546
 547 static void print_graph_cpu(struct trace_seq *s, int cpu)
 548 {
 549         /*
 550          * Start with a space character - to make it stand out
 551          * to the right a bit when trace output is pasted into
 552          * email:
 553          */
 554         trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
 555 }
 556
 557 #define TRACE_GRAPH_PROCINFO_LENGTH     14
 558
 559 static void print_graph_proc(struct trace_seq *s, pid_t pid)
 560 {
 561         char comm[TASK_COMM_LEN];
 562         /* sign + log10(MAX_INT) + '\0' */
 563         char pid_str[11];
 564         int spaces = 0;
 565         int len;
 566         int i;
 567
 568         trace_find_cmdline(pid, comm);
 569         comm[7] = '\0';
 570         sprintf(pid_str, "%d", pid);
 571
 572         /* 1 stands for the "-" character */
 573         len = strlen(comm) + strlen(pid_str) + 1;
 574
 575         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
 576                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
 577
 578         /* First spaces to align center */
 579         for (i = 0; i < spaces / 2; i++)
 580                 trace_seq_putc(s, ' ');
 581
 582         trace_seq_printf(s, "%s-%s", comm, pid_str);
 583
 584         /* Last spaces to align center */
 585         for (i = 0; i < spaces - (spaces / 2); i++)
 586                 trace_seq_putc(s, ' ');
 587 }
 588
 589
 590 static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
 591 {
 592         trace_seq_putc(s, ' ');
 593         trace_print_lat_fmt(s, entry);
 594 }
 595
 596 /* If the pid changed since the last trace, output this event */
 597 static void
 598 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
 599 {
 600         pid_t prev_pid;
 601         pid_t *last_pid;
 602
 603         if (!data)
 604                 return;
 605
 606         last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
 607
 608         if (*last_pid == pid)
 609                 return;
 610
 611         prev_pid = *last_pid;
 612         *last_pid = pid;
 613
 614         if (prev_pid == -1)
 615                 return;
 616 /*
 617  * Context-switch trace line:
 618
 619  ------------------------------------------
 620  | 1)  migration/0--1  =>  sshd-1755
 621  ------------------------------------------
 622
 623  */
 624         trace_seq_puts(s, " ------------------------------------------\n");
 625         print_graph_cpu(s, cpu);
 626         print_graph_proc(s, prev_pid);
 627         trace_seq_puts(s, " => ");
 628         print_graph_proc(s, pid);
 629         trace_seq_puts(s, "\n ------------------------------------------\n\n");
 630 }
 631
 632 static struct ftrace_graph_ret_entry *
 633 get_return_for_leaf(struct trace_iterator *iter,
 634                 struct ftrace_graph_ent_entry *curr)
 635 {
 636         struct fgraph_data *data = iter->private;
 637         struct ring_buffer_iter *ring_iter = NULL;
 638         struct ring_buffer_event *event;
 639         struct ftrace_graph_ret_entry *next;
 640
 641         /*
 642          * If the previous output failed to write to the seq buffer,
 643          * then we just reuse the data from before.
 644          */
 645         if (data && data->failed) {
 646                 curr = &data->ent;
 647                 next = &data->ret;
 648         } else {
 649
 650                 ring_iter = trace_buffer_iter(iter, iter->cpu);
 651
 652                 /* First peek to compare current entry and the next one */
 653                 if (ring_iter)
 654                         event = ring_buffer_iter_peek(ring_iter, NULL);
 655                 else {
 656                         /*
 657                          * We need to consume the current entry to see
 658                          * the next one.
 659                          */
 660                         ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
 661                                             NULL, NULL);
 662                         event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
 663                                                  NULL, NULL);
 664                 }
 665
 666                 if (!event)
 667                         return NULL;
 668
 669                 next = ring_buffer_event_data(event);
 670
 671                 if (data) {
 672                         /*
 673                          * Save current and next entries for later reference
 674                          * if the output fails.
 675                          */
 676                         data->ent = *curr;
 677                         /*
 678                          * If the next event is not a return type, then
 679                          * we only care about what type it is. Otherwise we can
 680                          * safely copy the entire event.
 681                          */
 682                         if (next->ent.type == TRACE_GRAPH_RET)
 683                                 data->ret = *next;
 684                         else
 685                                 data->ret.ent.type = next->ent.type;
 686                 }
 687         }
 688
 689         if (next->ent.type != TRACE_GRAPH_RET)
 690                 return NULL;
 691
 692         if (curr->ent.pid != next->ent.pid ||
 693                         curr->graph_ent.func != next->ret.func)
 694                 return NULL;
 695
 696         /* this is a leaf, now advance the iterator */
 697         if (ring_iter)
 698                 ring_buffer_read(ring_iter, NULL);
 699
 700         return next;
 701 }
 702
 703 static void print_graph_abs_time(u64 t, struct trace_seq *s)
 704 {
 705         unsigned long usecs_rem;
 706
 707         usecs_rem = do_div(t, NSEC_PER_SEC);
 708         usecs_rem /= 1000;
 709
 710         trace_seq_printf(s, "%5lu.%06lu |  ",
 711                          (unsigned long)t, usecs_rem);
 712 }
 713
 714 static void
 715 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 716                 enum trace_type type, int cpu, pid_t pid, u32 flags)
 717 {
 718         struct trace_array *tr = iter->tr;
 719         struct trace_seq *s = &iter->seq;
 720         struct trace_entry *ent = iter->ent;
 721
 722         if (addr < (unsigned long)__irqentry_text_start ||
 723                 addr >= (unsigned long)__irqentry_text_end)
 724                 return;
 725
 726         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
 727                 /* Absolute time */
 728                 if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
 729                         print_graph_abs_time(iter->ts, s);
 730
 731                 /* Cpu */
 732                 if (flags & TRACE_GRAPH_PRINT_CPU)
 733                         print_graph_cpu(s, cpu);
 734
 735                 /* Proc */
 736                 if (flags & TRACE_GRAPH_PRINT_PROC) {
 737                         print_graph_proc(s, pid);
 738                         trace_seq_puts(s, " | ");
 739                 }
 740
 741                 /* Latency format */
 742                 if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
 743                         print_graph_lat_fmt(s, ent);
 744         }
 745
 746         /* No overhead */
 747         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_START);
 748
 749         if (type == TRACE_GRAPH_ENT)
 750                 trace_seq_puts(s, "==========>");
 751         else
 752                 trace_seq_puts(s, "<==========");
 753
 754         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_END);
 755         trace_seq_putc(s, '\n');
 756 }
 757
 758 void
 759 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 760 {
 761         unsigned long nsecs_rem = do_div(duration, 1000);
 762         /* log10(ULONG_MAX) + '\0' */
 763         char usecs_str[21];
 764         char nsecs_str[5];
 765         int len;
 766         int i;
 767
 768         sprintf(usecs_str, "%lu", (unsigned long) duration);
 769
 770         /* Print msecs */
 771         trace_seq_printf(s, "%s", usecs_str);
 772
 773         len = strlen(usecs_str);
 774
 775         /* Print nsecs (we don't want to exceed 7 numbers) */
 776         if (len < 7) {
 777                 size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);
 778
 779                 snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
 780                 trace_seq_printf(s, ".%s", nsecs_str);
 781                 len += strlen(nsecs_str) + 1;
 782         }
 783
 784         trace_seq_puts(s, " us ");
 785
 786         /* Print remaining spaces to fit the row's width */
 787         for (i = len; i < 8; i++)
 788                 trace_seq_putc(s, ' ');
 789 }
 790
 791 static void
 792 print_graph_duration(struct trace_array *tr, unsigned long long duration,
 793                      struct trace_seq *s, u32 flags)
 794 {
 795         if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
 796             !(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
 797                 return;
 798
 799         /* No real adata, just filling the column with spaces */
 800         switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) {
 801         case FLAGS_FILL_FULL:
 802                 trace_seq_puts(s, "              |  ");
 803                 return;
 804         case FLAGS_FILL_START:
 805                 trace_seq_puts(s, "  ");
 806                 return;
 807         case FLAGS_FILL_END:
 808                 trace_seq_puts(s, " |");
 809                 return;
 810         }
 811
 812         /* Signal a overhead of time execution to the output */
 813         if (flags & TRACE_GRAPH_PRINT_OVERHEAD)
 814                 trace_seq_printf(s, "%c ", trace_find_mark(duration));
 815         else
 816                 trace_seq_puts(s, "  ");
 817
 818         trace_print_graph_duration(duration, s);
 819         trace_seq_puts(s, "|  ");
 820 }
 821
 822 /* Case of a leaf function on its call entry */
 823 static enum print_line_t
 824 print_graph_entry_leaf(struct trace_iterator *iter,
 825                 struct ftrace_graph_ent_entry *entry,
 826                 struct ftrace_graph_ret_entry *ret_entry,
 827                 struct trace_seq *s, u32 flags)
 828 {
 829         struct fgraph_data *data = iter->private;
 830         struct trace_array *tr = iter->tr;
 831         struct ftrace_graph_ret *graph_ret;
 832         struct ftrace_graph_ent *call;
 833         unsigned long long duration;
 834         int cpu = iter->cpu;
 835         int i;
 836
 837         graph_ret = &ret_entry->ret;
 838         call = &entry->graph_ent;
 839         duration = graph_ret->rettime - graph_ret->calltime;
 840
 841         if (data) {
 842                 struct fgraph_cpu_data *cpu_data;
 843
 844                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
 845
 846                 /* If a graph tracer ignored set_graph_notrace */
 847                 if (call->depth < -1)
 848                         call->depth += FTRACE_NOTRACE_DEPTH;
 849
 850                 /*
 851                  * Comments display at + 1 to depth. Since
 852                  * this is a leaf function, keep the comments
 853                  * equal to this depth.
 854                  */
 855                 cpu_data->depth = call->depth - 1;
 856
 857                 /* No need to keep this function around for this depth */
 858                 if (call->depth < FTRACE_RETFUNC_DEPTH &&
 859                     !WARN_ON_ONCE(call->depth < 0))
 860                         cpu_data->enter_funcs[call->depth] = 0;
 861         }
 862
 863         /* Overhead and duration */
 864         print_graph_duration(tr, duration, s, flags);
 865
 866         /* Function */
 867         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
 868                 trace_seq_putc(s, ' ');
 869
 870         trace_seq_printf(s, "%ps();\n", (void *)call->func);
 871
 872         print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET,
 873                         cpu, iter->ent->pid, flags);
 874
 875         return trace_handle_return(s);
 876 }
 877
 878 static enum print_line_t
 879 print_graph_entry_nested(struct trace_iterator *iter,
 880                          struct ftrace_graph_ent_entry *entry,
 881                          struct trace_seq *s, int cpu, u32 flags)
 882 {
 883         struct ftrace_graph_ent *call = &entry->graph_ent;
 884         struct fgraph_data *data = iter->private;
 885         struct trace_array *tr = iter->tr;
 886         int i;
 887
 888         if (data) {
 889                 struct fgraph_cpu_data *cpu_data;
 890                 int cpu = iter->cpu;
 891
 892                 /* If a graph tracer ignored set_graph_notrace */
 893                 if (call->depth < -1)
 894                         call->depth += FTRACE_NOTRACE_DEPTH;
 895
 896                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
 897                 cpu_data->depth = call->depth;
 898
 899                 /* Save this function pointer to see if the exit matches */
 900                 if (call->depth < FTRACE_RETFUNC_DEPTH &&
 901                     !WARN_ON_ONCE(call->depth < 0))
 902                         cpu_data->enter_funcs[call->depth] = call->func;
 903         }
 904
 905         /* No time */
 906         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
 907
 908         /* Function */
 909         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
 910                 trace_seq_putc(s, ' ');
 911
 912         trace_seq_printf(s, "%ps() {\n", (void *)call->func);
 913
 914         if (trace_seq_has_overflowed(s))
 915                 return TRACE_TYPE_PARTIAL_LINE;
 916
 917         /*
 918          * we already consumed the current entry to check the next one
 919          * and see if this is a leaf.
 920          */
 921         return TRACE_TYPE_NO_CONSUME;
 922 }
 923
 924 static void
 925 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
 926                      int type, unsigned long addr, u32 flags)
 927 {
 928         struct fgraph_data *data = iter->private;
 929         struct trace_entry *ent = iter->ent;
 930         struct trace_array *tr = iter->tr;
 931         int cpu = iter->cpu;
 932
 933         /* Pid */
 934         verif_pid(s, ent->pid, cpu, data);
 935
 936         if (type)
 937                 /* Interrupt */
 938                 print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
 939
 940         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
 941                 return;
 942
 943         /* Absolute time */
 944         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
 945                 print_graph_abs_time(iter->ts, s);
 946
 947         /* Cpu */
 948         if (flags & TRACE_GRAPH_PRINT_CPU)
 949                 print_graph_cpu(s, cpu);
 950
 951         /* Proc */
 952         if (flags & TRACE_GRAPH_PRINT_PROC) {
 953                 print_graph_proc(s, ent->pid);
 954                 trace_seq_puts(s, " | ");
 955         }
 956
 957         /* Latency format */
 958         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
 959                 print_graph_lat_fmt(s, ent);
 960
 961         return;
 962 }
 963
 964 /*
 965  * Entry check for irq code
 966  *
 967  * returns 1 if
 968  *  - we are inside irq code
 969  *  - we just entered irq code
 970  *
 971  * retunns 0 if
 972  *  - funcgraph-interrupts option is set
 973  *  - we are not inside irq code
 974  */
 975 static int
 976 check_irq_entry(struct trace_iterator *iter, u32 flags,
 977                 unsigned long addr, int depth)
 978 {
 979         int cpu = iter->cpu;
 980         int *depth_irq;
 981         struct fgraph_data *data = iter->private;
 982
 983         /*
 984          * If we are either displaying irqs, or we got called as
 985          * a graph event and private data does not exist,
 986          * then we bypass the irq check.
 987          */
 988         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
 989             (!data))
 990                 return 0;
 991
 992         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
 993
 994         /*
 995          * We are inside the irq code
 996          */
 997         if (*depth_irq >= 0)
 998                 return 1;
 999
1000         if ((addr < (unsigned long)__irqentry_text_start) ||
1001             (addr >= (unsigned long)__irqentry_text_end))
1002                 return 0;
1003
1004         /*
1005          * We are entering irq code.
1006          */
1007         *depth_irq = depth;
1008         return 1;
1009 }
1010
1011 /*
1012  * Return check for irq code
1013  *
1014  * returns 1 if
1015  *  - we are inside irq code
1016  *  - we just left irq code
1017  *
1018  * returns 0 if
1019  *  - funcgraph-interrupts option is set
1020  *  - we are not inside irq code
1021  */
1022 static int
1023 check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
1024 {
1025         int cpu = iter->cpu;
1026         int *depth_irq;
1027         struct fgraph_data *data = iter->private;
1028
1029         /*
1030          * If we are either displaying irqs, or we got called as
1031          * a graph event and private data does not exist,
1032          * then we bypass the irq check.
1033          */
1034         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
1035             (!data))
1036                 return 0;
1037
1038         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1039
1040         /*
1041          * We are not inside the irq code.
1042          */
1043         if (*depth_irq == -1)
1044                 return 0;
1045
1046         /*
1047          * We are inside the irq code, and this is returning entry.
1048          * Let's not trace it and clear the entry depth, since
1049          * we are out of irq code.
1050          *
1051          * This condition ensures that we 'leave the irq code' once
1052          * we are out of the entry depth. Thus protecting us from
1053          * the RETURN entry loss.
1054          */
1055         if (*depth_irq >= depth) {
1056                 *depth_irq = -1;
1057                 return 1;
1058         }
1059
1060         /*
1061          * We are inside the irq code, and this is not the entry.
1062          */
1063         return 1;
1064 }
1065
1066 static enum print_line_t
1067 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
1068                         struct trace_iterator *iter, u32 flags)
1069 {
1070         struct fgraph_data *data = iter->private;
1071         struct ftrace_graph_ent *call = &field->graph_ent;
1072         struct ftrace_graph_ret_entry *leaf_ret;
1073         static enum print_line_t ret;
1074         int cpu = iter->cpu;
1075
1076         if (check_irq_entry(iter, flags, call->func, call->depth))
1077                 return TRACE_TYPE_HANDLED;
1078
1079         print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags);
1080
1081         leaf_ret = get_return_for_leaf(iter, field);
1082         if (leaf_ret)
1083                 ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
1084         else
1085                 ret = print_graph_entry_nested(iter, field, s, cpu, flags);
1086
1087         if (data) {
1088                 /*
1089                  * If we failed to write our output, then we need to make
1090                  * note of it. Because we already consumed our entry.
1091                  */
1092                 if (s->full) {
1093                         data->failed = 1;
1094                         data->cpu = cpu;
1095                 } else
1096                         data->failed = 0;
1097         }
1098
1099         return ret;
1100 }
1101
1102 static enum print_line_t
1103 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
1104                    struct trace_entry *ent, struct trace_iterator *iter,
1105                    u32 flags)
1106 {
1107         unsigned long long duration = trace->rettime - trace->calltime;
1108         struct fgraph_data *data = iter->private;
1109         struct trace_array *tr = iter->tr;
1110         pid_t pid = ent->pid;
1111         int cpu = iter->cpu;
1112         int func_match = 1;
1113         int i;
1114
1115         if (check_irq_return(iter, flags, trace->depth))
1116                 return TRACE_TYPE_HANDLED;
1117
1118         if (data) {
1119                 struct fgraph_cpu_data *cpu_data;
1120                 int cpu = iter->cpu;
1121
1122                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
1123
1124                 /*
1125                  * Comments display at + 1 to depth. This is the
1126                  * return from a function, we now want the comments
1127                  * to display at the same level of the bracket.
1128                  */
1129                 cpu_data->depth = trace->depth - 1;
1130
1131                 if (trace->depth < FTRACE_RETFUNC_DEPTH &&
1132                     !WARN_ON_ONCE(trace->depth < 0)) {
1133                         if (cpu_data->enter_funcs[trace->depth] != trace->func)
1134                                 func_match = 0;
1135                         cpu_data->enter_funcs[trace->depth] = 0;
1136                 }
1137         }
1138
1139         print_graph_prologue(iter, s, 0, 0, flags);
1140
1141         /* Overhead and duration */
1142         print_graph_duration(tr, duration, s, flags);
1143
1144         /* Closing brace */
1145         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
1146                 trace_seq_putc(s, ' ');
1147
1148         /*
1149          * If the return function does not have a matching entry,
1150          * then the entry was lost. Instead of just printing
1151          * the '}' and letting the user guess what function this
1152          * belongs to, write out the function name. Always do
1153          * that if the funcgraph-tail option is enabled.
1154          */
1155         if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
1156                 trace_seq_puts(s, "}\n");
1157         else
1158                 trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
1159
1160         /* Overrun */
1161         if (flags & TRACE_GRAPH_PRINT_OVERRUN)
1162                 trace_seq_printf(s, " (Overruns: %lu)\n",
1163                                  trace->overrun);
1164
1165         print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
1166                         cpu, pid, flags);
1167
1168         return trace_handle_return(s);
1169 }
1170
1171 static enum print_line_t
1172 print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
1173                     struct trace_iterator *iter, u32 flags)
1174 {
1175         struct trace_array *tr = iter->tr;
1176         unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK);
1177         struct fgraph_data *data = iter->private;
1178         struct trace_event *event;
1179         int depth = 0;
1180         int ret;
1181         int i;
1182
1183         if (data)
1184                 depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;
1185
1186         print_graph_prologue(iter, s, 0, 0, flags);
1187
1188         /* No time */
1189         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
1190
1191         /* Indentation */
1192         if (depth > 0)
1193                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++)
1194                         trace_seq_putc(s, ' ');
1195
1196         /* The comment */
1197         trace_seq_puts(s, "/* ");
1198
1199         switch (iter->ent->type) {
1200         case TRACE_BPUTS:
1201                 ret = trace_print_bputs_msg_only(iter);
1202                 if (ret != TRACE_TYPE_HANDLED)
1203                         return ret;
1204                 break;
1205         case TRACE_BPRINT:
1206                 ret = trace_print_bprintk_msg_only(iter);
1207                 if (ret != TRACE_TYPE_HANDLED)
1208                         return ret;
1209                 break;
1210         case TRACE_PRINT:
1211                 ret = trace_print_printk_msg_only(iter);
1212                 if (ret != TRACE_TYPE_HANDLED)
1213                         return ret;
1214                 break;
1215         default:
1216                 event = ftrace_find_event(ent->type);
1217                 if (!event)
1218                         return TRACE_TYPE_UNHANDLED;
1219
1220                 ret = event->funcs->trace(iter, sym_flags, event);
1221                 if (ret != TRACE_TYPE_HANDLED)
1222                         return ret;
1223         }
1224
1225         if (trace_seq_has_overflowed(s))
1226                 goto out;
1227
1228         /* Strip ending newline */
1229         if (s->buffer[s->seq.len - 1] == '\n') {
1230                 s->buffer[s->seq.len - 1] = '\0';
1231                 s->seq.len--;
1232         }
1233
1234         trace_seq_puts(s, " */\n");
1235  out:
1236         return trace_handle_return(s);
1237 }
1238
1239
1240 enum print_line_t
1241 print_graph_function_flags(struct trace_iterator *iter, u32 flags)
1242 {
1243         struct ftrace_graph_ent_entry *field;
1244         struct fgraph_data *data = iter->private;
1245         struct trace_entry *entry = iter->ent;
1246         struct trace_seq *s = &iter->seq;
1247         int cpu = iter->cpu;
1248         int ret;
1249
1250         if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
1251                 per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
1252                 return TRACE_TYPE_HANDLED;
1253         }
1254
1255         /*
1256          * If the last output failed, there's a possibility we need
1257          * to print out the missing entry which would never go out.
1258          */
1259         if (data && data->failed) {
1260                 field = &data->ent;
1261                 iter->cpu = data->cpu;
1262                 ret = print_graph_entry(field, s, iter, flags);
1263                 if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
1264                         per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
1265                         ret = TRACE_TYPE_NO_CONSUME;
1266                 }
1267                 iter->cpu = cpu;
1268                 return ret;
1269         }
1270
1271         switch (entry->type) {
1272         case TRACE_GRAPH_ENT: {
1273                 /*
1274                  * print_graph_entry() may consume the current event,
1275                  * thus @field may become invalid, so we need to save it.
1276                  * sizeof(struct ftrace_graph_ent_entry) is very small,
1277                  * it can be safely saved at the stack.
1278                  */
1279                 struct ftrace_graph_ent_entry saved;
1280                 trace_assign_type(field, entry);
1281                 saved = *field;
1282                 return print_graph_entry(&saved, s, iter, flags);
1283         }
1284         case TRACE_GRAPH_RET: {
1285                 struct ftrace_graph_ret_entry *field;
1286                 trace_assign_type(field, entry);
1287                 return print_graph_return(&field->ret, s, entry, iter, flags);
1288         }
1289         case TRACE_STACK:
1290         case TRACE_FN:
1291                 /* dont trace stack and functions as comments */
1292                 return TRACE_TYPE_UNHANDLED;
1293
1294         default:
1295                 return print_graph_comment(s, entry, iter, flags);
1296         }
1297
1298         return TRACE_TYPE_HANDLED;
1299 }
1300
1301 static enum print_line_t
1302 print_graph_function(struct trace_iterator *iter)
1303 {
1304         return print_graph_function_flags(iter, tracer_flags.val);
1305 }
1306
1307 static enum print_line_t
1308 print_graph_function_event(struct trace_iterator *iter, int flags,
1309                            struct trace_event *event)
1310 {
1311         return print_graph_function(iter);
1312 }
1313
1314 static void print_lat_header(struct seq_file *s, u32 flags)
1315 {
1316         static const char spaces[] = "                " /* 16 spaces */
1317                 "    "                                  /* 4 spaces */
1318                 "                 ";                    /* 17 spaces */
1319         int size = 0;
1320
1321         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1322                 size += 16;
1323         if (flags & TRACE_GRAPH_PRINT_CPU)
1324                 size += 4;
1325         if (flags & TRACE_GRAPH_PRINT_PROC)
1326                 size += 17;
1327
1328         seq_printf(s, "#%.*s  _-----=> irqs-off        \n", size, spaces);
1329         seq_printf(s, "#%.*s / _----=> need-resched    \n", size, spaces);
1330         seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
1331         seq_printf(s, "#%.*s|| / _--=> preempt-depth   \n", size, spaces);
1332         seq_printf(s, "#%.*s||| /                      \n", size, spaces);
1333 }
1334
1335 static void __print_graph_headers_flags(struct trace_array *tr,
1336                                         struct seq_file *s, u32 flags)
1337 {
1338         int lat = tr->trace_flags & TRACE_ITER_LATENCY_FMT;
1339
1340         if (lat)
1341                 print_lat_header(s, flags);
1342
1343         /* 1st line */
1344         seq_putc(s, '#');
1345         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1346                 seq_puts(s, "     TIME       ");
1347         if (flags & TRACE_GRAPH_PRINT_CPU)
1348                 seq_puts(s, " CPU");
1349         if (flags & TRACE_GRAPH_PRINT_PROC)
1350                 seq_puts(s, "  TASK/PID       ");
1351         if (lat)
1352                 seq_puts(s, "||||");
1353         if (flags & TRACE_GRAPH_PRINT_DURATION)
1354                 seq_puts(s, "  DURATION   ");
1355         seq_puts(s, "               FUNCTION CALLS\n");
1356
1357         /* 2nd line */
1358         seq_putc(s, '#');
1359         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1360                 seq_puts(s, "      |         ");
1361         if (flags & TRACE_GRAPH_PRINT_CPU)
1362                 seq_puts(s, " |  ");
1363         if (flags & TRACE_GRAPH_PRINT_PROC)
1364                 seq_puts(s, "   |    |        ");
1365         if (lat)
1366                 seq_puts(s, "||||");
1367         if (flags & TRACE_GRAPH_PRINT_DURATION)
1368                 seq_puts(s, "   |   |      ");
1369         seq_puts(s, "               |   |   |   |\n");
1370 }
1371
1372 static void print_graph_headers(struct seq_file *s)
1373 {
1374         print_graph_headers_flags(s, tracer_flags.val);
1375 }
1376
1377 void print_graph_headers_flags(struct seq_file *s, u32 flags)
1378 {
1379         struct trace_iterator *iter = s->private;
1380         struct trace_array *tr = iter->tr;
1381
1382         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
1383                 return;
1384
1385         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) {
1386                 /* print nothing if the buffers are empty */
1387                 if (trace_empty(iter))
1388                         return;
1389
1390                 print_trace_header(s, iter);
1391         }
1392
1393         __print_graph_headers_flags(tr, s, flags);
1394 }
1395
1396 void graph_trace_open(struct trace_iterator *iter)
1397 {
1398         /* pid and depth on the last trace processed */
1399         struct fgraph_data *data;
1400         gfp_t gfpflags;
1401         int cpu;
1402
1403         iter->private = NULL;
1404
1405         /* We can be called in atomic context via ftrace_dump() */
1406         gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
1407
1408         data = kzalloc(sizeof(*data), gfpflags);
1409         if (!data)
1410                 goto out_err;
1411
1412         data->cpu_data = alloc_percpu_gfp(struct fgraph_cpu_data, gfpflags);
1413         if (!data->cpu_data)
1414                 goto out_err_free;
1415
1416         for_each_possible_cpu(cpu) {
1417                 pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
1418                 int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
1419                 int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
1420                 int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1421
1422                 *pid = -1;
1423                 *depth = 0;
1424                 *ignore = 0;
1425                 *depth_irq = -1;
1426         }
1427
1428         iter->private = data;
1429
1430         return;
1431
1432  out_err_free:
1433         kfree(data);
1434  out_err:
1435         pr_warn("function graph tracer: not enough memory\n");
1436 }
1437
1438 void graph_trace_close(struct trace_iterator *iter)
1439 {
1440         struct fgraph_data *data = iter->private;
1441
1442         if (data) {
1443                 free_percpu(data->cpu_data);
1444                 kfree(data);
1445         }
1446 }
1447
1448 static int
1449 func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1450 {
1451         if (bit == TRACE_GRAPH_PRINT_IRQS)
1452                 ftrace_graph_skip_irqs = !set;
1453
1454         if (bit == TRACE_GRAPH_SLEEP_TIME)
1455                 ftrace_graph_sleep_time_control(set);
1456
1457         if (bit == TRACE_GRAPH_GRAPH_TIME)
1458                 ftrace_graph_graph_time_control(set);
1459
1460         return 0;
1461 }
1462
1463 static struct trace_event_functions graph_functions = {
1464         .trace          = print_graph_function_event,
1465 };
1466
1467 static struct trace_event graph_trace_entry_event = {
1468         .type           = TRACE_GRAPH_ENT,
1469         .funcs          = &graph_functions,
1470 };
1471
1472 static struct trace_event graph_trace_ret_event = {
1473         .type           = TRACE_GRAPH_RET,
1474         .funcs          = &graph_functions
1475 };
1476
1477 static struct tracer graph_trace __tracer_data = {
1478         .name           = "function_graph",
1479         .update_thresh  = graph_trace_update_thresh,
1480         .open           = graph_trace_open,
1481         .pipe_open      = graph_trace_open,
1482         .close          = graph_trace_close,
1483         .pipe_close     = graph_trace_close,
1484         .init           = graph_trace_init,
1485         .reset          = graph_trace_reset,
1486         .print_line     = print_graph_function,
1487         .print_header   = print_graph_headers,
1488         .flags          = &tracer_flags,
1489         .set_flag       = func_graph_set_flag,
1490 #ifdef CONFIG_FTRACE_SELFTEST
1491         .selftest       = trace_selftest_startup_function_graph,
1492 #endif
1493 };
1494
1495
1496 static ssize_t
1497 graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt,
1498                   loff_t *ppos)
1499 {
1500         unsigned long val;
1501         int ret;
1502
1503         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
1504         if (ret)
1505                 return ret;
1506
1507         fgraph_max_depth = val;
1508
1509         *ppos += cnt;
1510
1511         return cnt;
1512 }
1513
1514 static ssize_t
1515 graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt,
1516                  loff_t *ppos)
1517 {
1518         char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/
1519         int n;
1520
1521         n = sprintf(buf, "%d\n", fgraph_max_depth);
1522
1523         return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
1524 }
1525
1526 static const struct file_operations graph_depth_fops = {
1527         .open           = tracing_open_generic,
1528         .write          = graph_depth_write,
1529         .read           = graph_depth_read,
1530         .llseek         = generic_file_llseek,
1531 };
1532
1533 static __init int init_graph_tracefs(void)
1534 {
1535         struct dentry *d_tracer;
1536
1537         d_tracer = tracing_init_dentry();
1538         if (IS_ERR(d_tracer))
1539                 return 0;
1540
1541         trace_create_file("max_graph_depth", 0644, d_tracer,
1542                           NULL, &graph_depth_fops);
1543
1544         return 0;
1545 }
1546 fs_initcall(init_graph_tracefs);
1547
1548 static __init int init_graph_trace(void)
1549 {
1550         max_bytes_for_cpu = snprintf(NULL, 0, "%u", nr_cpu_ids - 1);
1551
1552         if (!register_trace_event(&graph_trace_entry_event)) {
1553                 pr_warn("Warning: could not register graph trace events\n");
1554                 return 1;
1555         }
1556
1557         if (!register_trace_event(&graph_trace_ret_event)) {
1558                 pr_warn("Warning: could not register graph trace events\n");
1559                 return 1;
1560         }
1561
1562         return register_tracer(&graph_trace);
1563 }
1564
1565 core_initcall(init_graph_trace);