kernel/trace/trace.h

   1 #ifndef _LINUX_KERNEL_TRACE_H
   2 #define _LINUX_KERNEL_TRACE_H
   3
   4 #include <linux/fs.h>
   5 #include <asm/atomic.h>
   6 #include <linux/sched.h>
   7 #include <linux/clocksource.h>
   8 #include <linux/ring_buffer.h>
   9 #include <linux/mmiotrace.h>
  10 #include <linux/ftrace.h>
  11 #include <trace/boot.h>
  12 #include <trace/kmemtrace.h>
  13 #include <trace/power.h>
  14
  15 enum trace_type {
  16         __TRACE_FIRST_TYPE = 0,
  17
  18         TRACE_FN,
  19         TRACE_CTX,
  20         TRACE_WAKE,
  21         TRACE_STACK,
  22         TRACE_PRINT,
  23         TRACE_SPECIAL,
  24         TRACE_MMIO_RW,
  25         TRACE_MMIO_MAP,
  26         TRACE_BRANCH,
  27         TRACE_BOOT_CALL,
  28         TRACE_BOOT_RET,
  29         TRACE_GRAPH_RET,
  30         TRACE_GRAPH_ENT,
  31         TRACE_USER_STACK,
  32         TRACE_HW_BRANCHES,
  33         TRACE_SYSCALL_ENTER,
  34         TRACE_SYSCALL_EXIT,
  35         TRACE_KMEM_ALLOC,
  36         TRACE_KMEM_FREE,
  37         TRACE_POWER,
  38         TRACE_BLK,
  39
  40         __TRACE_LAST_TYPE,
  41 };
  42
  43 /*
  44  * The trace entry - the most basic unit of tracing. This is what
  45  * is printed in the end as a single line in the trace output, such as:
  46  *
  47  *     bash-15816 [01]   235.197585: idle_cpu <- irq_enter
  48  */
  49 struct trace_entry {
  50         unsigned char           type;
  51         unsigned char           flags;
  52         unsigned char           preempt_count;
  53         int                     pid;
  54         int                     tgid;
  55 };
  56
  57 /*
  58  * Function trace entry - function address and parent function addres:
  59  */
  60 struct ftrace_entry {
  61         struct trace_entry      ent;
  62         unsigned long           ip;
  63         unsigned long           parent_ip;
  64 };
  65
  66 /* Function call entry */
  67 struct ftrace_graph_ent_entry {
  68         struct trace_entry              ent;
  69         struct ftrace_graph_ent         graph_ent;
  70 };
  71
  72 /* Function return entry */
  73 struct ftrace_graph_ret_entry {
  74         struct trace_entry              ent;
  75         struct ftrace_graph_ret         ret;
  76 };
  77 extern struct tracer boot_tracer;
  78
  79 /*
  80  * Context switch trace entry - which task (and prio) we switched from/to:
  81  */
  82 struct ctx_switch_entry {
  83         struct trace_entry      ent;
  84         unsigned int            prev_pid;
  85         unsigned char           prev_prio;
  86         unsigned char           prev_state;
  87         unsigned int            next_pid;
  88         unsigned char           next_prio;
  89         unsigned char           next_state;
  90         unsigned int            next_cpu;
  91 };
  92
  93 /*
  94  * Special (free-form) trace entry:
  95  */
  96 struct special_entry {
  97         struct trace_entry      ent;
  98         unsigned long           arg1;
  99         unsigned long           arg2;
 100         unsigned long           arg3;
 101 };
 102
 103 /*
 104  * Stack-trace entry:
 105  */
 106
 107 #define FTRACE_STACK_ENTRIES    8
 108
 109 struct stack_entry {
 110         struct trace_entry      ent;
 111         unsigned long           caller[FTRACE_STACK_ENTRIES];
 112 };
 113
 114 struct userstack_entry {
 115         struct trace_entry      ent;
 116         unsigned long           caller[FTRACE_STACK_ENTRIES];
 117 };
 118
 119 /*
 120  * trace_printk entry:
 121  */
 122 struct print_entry {
 123         struct trace_entry      ent;
 124         unsigned long           ip;
 125         int                     depth;
 126         const char              *fmt;
 127         u32                     buf[];
 128 };
 129
 130 #define TRACE_OLD_SIZE          88
 131
 132 struct trace_field_cont {
 133         unsigned char           type;
 134         /* Temporary till we get rid of this completely */
 135         char                    buf[TRACE_OLD_SIZE - 1];
 136 };
 137
 138 struct trace_mmiotrace_rw {
 139         struct trace_entry      ent;
 140         struct mmiotrace_rw     rw;
 141 };
 142
 143 struct trace_mmiotrace_map {
 144         struct trace_entry      ent;
 145         struct mmiotrace_map    map;
 146 };
 147
 148 struct trace_boot_call {
 149         struct trace_entry      ent;
 150         struct boot_trace_call boot_call;
 151 };
 152
 153 struct trace_boot_ret {
 154         struct trace_entry      ent;
 155         struct boot_trace_ret boot_ret;
 156 };
 157
 158 #define TRACE_FUNC_SIZE 30
 159 #define TRACE_FILE_SIZE 20
 160 struct trace_branch {
 161         struct trace_entry      ent;
 162         unsigned                line;
 163         char                    func[TRACE_FUNC_SIZE+1];
 164         char                    file[TRACE_FILE_SIZE+1];
 165         char                    correct;
 166 };
 167
 168 struct hw_branch_entry {
 169         struct trace_entry      ent;
 170         u64                     from;
 171         u64                     to;
 172 };
 173
 174 struct trace_power {
 175         struct trace_entry      ent;
 176         struct power_trace      state_data;
 177 };
 178
 179 struct kmemtrace_alloc_entry {
 180         struct trace_entry      ent;
 181         enum kmemtrace_type_id type_id;
 182         unsigned long call_site;
 183         const void *ptr;
 184         size_t bytes_req;
 185         size_t bytes_alloc;
 186         gfp_t gfp_flags;
 187         int node;
 188 };
 189
 190 struct kmemtrace_free_entry {
 191         struct trace_entry      ent;
 192         enum kmemtrace_type_id type_id;
 193         unsigned long call_site;
 194         const void *ptr;
 195 };
 196
 197 /*
 198  * trace_flag_type is an enumeration that holds different
 199  * states when a trace occurs. These are:
 200  *  IRQS_OFF            - interrupts were disabled
 201  *  IRQS_NOSUPPORT      - arch does not support irqs_disabled_flags
 202  *  NEED_RESCED         - reschedule is requested
 203  *  HARDIRQ             - inside an interrupt handler
 204  *  SOFTIRQ             - inside a softirq handler
 205  */
 206 enum trace_flag_type {
 207         TRACE_FLAG_IRQS_OFF             = 0x01,
 208         TRACE_FLAG_IRQS_NOSUPPORT       = 0x02,
 209         TRACE_FLAG_NEED_RESCHED         = 0x04,
 210         TRACE_FLAG_HARDIRQ              = 0x08,
 211         TRACE_FLAG_SOFTIRQ              = 0x10,
 212 };
 213
 214 #define TRACE_BUF_SIZE          1024
 215
 216 /*
 217  * The CPU trace array - it consists of thousands of trace entries
 218  * plus some other descriptor data: (for example which task started
 219  * the trace, etc.)
 220  */
 221 struct trace_array_cpu {
 222         atomic_t                disabled;
 223         void                    *buffer_page;   /* ring buffer spare */
 224
 225         /* these fields get copied into max-trace: */
 226         unsigned long           trace_idx;
 227         unsigned long           overrun;
 228         unsigned long           saved_latency;
 229         unsigned long           critical_start;
 230         unsigned long           critical_end;
 231         unsigned long           critical_sequence;
 232         unsigned long           nice;
 233         unsigned long           policy;
 234         unsigned long           rt_priority;
 235         cycle_t                 preempt_timestamp;
 236         pid_t                   pid;
 237         uid_t                   uid;
 238         char                    comm[TASK_COMM_LEN];
 239 };
 240
 241 struct trace_iterator;
 242
 243 /*
 244  * The trace array - an array of per-CPU trace arrays. This is the
 245  * highest level data structure that individual tracers deal with.
 246  * They have on/off state as well:
 247  */
 248 struct trace_array {
 249         struct ring_buffer      *buffer;
 250         unsigned long           entries;
 251         int                     cpu;
 252         cycle_t                 time_start;
 253         struct task_struct      *waiter;
 254         struct trace_array_cpu  *data[NR_CPUS];
 255 };
 256
 257 #define FTRACE_CMP_TYPE(var, type) \
 258         __builtin_types_compatible_p(typeof(var), type *)
 259
 260 #undef IF_ASSIGN
 261 #define IF_ASSIGN(var, entry, etype, id)                \
 262         if (FTRACE_CMP_TYPE(var, etype)) {              \
 263                 var = (typeof(var))(entry);             \
 264                 WARN_ON(id && (entry)->type != id);     \
 265                 break;                                  \
 266         }
 267
 268 /* Will cause compile errors if type is not found. */
 269 extern void __ftrace_bad_type(void);
 270
 271 /*
 272  * The trace_assign_type is a verifier that the entry type is
 273  * the same as the type being assigned. To add new types simply
 274  * add a line with the following format:
 275  *
 276  * IF_ASSIGN(var, ent, type, id);
 277  *
 278  *  Where "type" is the trace type that includes the trace_entry
 279  *  as the "ent" item. And "id" is the trace identifier that is
 280  *  used in the trace_type enum.
 281  *
 282  *  If the type can have more than one id, then use zero.
 283  */
 284 #define trace_assign_type(var, ent)                                     \
 285         do {                                                            \
 286                 IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN);     \
 287                 IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);        \
 288                 IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);   \
 289                 IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
 290                 IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);   \
 291                 IF_ASSIGN(var, ent, struct special_entry, 0);           \
 292                 IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,          \
 293                           TRACE_MMIO_RW);                               \
 294                 IF_ASSIGN(var, ent, struct trace_mmiotrace_map,         \
 295                           TRACE_MMIO_MAP);                              \
 296                 IF_ASSIGN(var, ent, struct trace_boot_call, TRACE_BOOT_CALL);\
 297                 IF_ASSIGN(var, ent, struct trace_boot_ret, TRACE_BOOT_RET);\
 298                 IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
 299                 IF_ASSIGN(var, ent, struct ftrace_graph_ent_entry,      \
 300                           TRACE_GRAPH_ENT);             \
 301                 IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,      \
 302                           TRACE_GRAPH_RET);             \
 303                 IF_ASSIGN(var, ent, struct hw_branch_entry, TRACE_HW_BRANCHES);\
 304                 IF_ASSIGN(var, ent, struct trace_power, TRACE_POWER); \
 305                 IF_ASSIGN(var, ent, struct kmemtrace_alloc_entry,       \
 306                           TRACE_KMEM_ALLOC);    \
 307                 IF_ASSIGN(var, ent, struct kmemtrace_free_entry,        \
 308                           TRACE_KMEM_FREE);     \
 309                 __ftrace_bad_type();                                    \
 310         } while (0)
 311
 312 /* Return values for print_line callback */
 313 enum print_line_t {
 314         TRACE_TYPE_PARTIAL_LINE = 0,    /* Retry after flushing the seq */
 315         TRACE_TYPE_HANDLED      = 1,
 316         TRACE_TYPE_UNHANDLED    = 2,    /* Relay to other output functions */
 317         TRACE_TYPE_NO_CONSUME   = 3     /* Handled but ask to not consume */
 318 };
 319
 320
 321 /*
 322  * An option specific to a tracer. This is a boolean value.
 323  * The bit is the bit index that sets its value on the
 324  * flags value in struct tracer_flags.
 325  */
 326 struct tracer_opt {
 327         const char      *name; /* Will appear on the trace_options file */
 328         u32             bit; /* Mask assigned in val field in tracer_flags */
 329 };
 330
 331 /*
 332  * The set of specific options for a tracer. Your tracer
 333  * have to set the initial value of the flags val.
 334  */
 335 struct tracer_flags {
 336         u32                     val;
 337         struct tracer_opt       *opts;
 338 };
 339
 340 /* Makes more easy to define a tracer opt */
 341 #define TRACER_OPT(s, b)        .name = #s, .bit = b
 342
 343
 344 /**
 345  * struct tracer - a specific tracer and its callbacks to interact with debugfs
 346  * @name: the name chosen to select it on the available_tracers file
 347  * @init: called when one switches to this tracer (echo name > current_tracer)
 348  * @reset: called when one switches to another tracer
 349  * @start: called when tracing is unpaused (echo 1 > tracing_enabled)
 350  * @stop: called when tracing is paused (echo 0 > tracing_enabled)
 351  * @open: called when the trace file is opened
 352  * @pipe_open: called when the trace_pipe file is opened
 353  * @wait_pipe: override how the user waits for traces on trace_pipe
 354  * @close: called when the trace file is released
 355  * @read: override the default read callback on trace_pipe
 356  * @splice_read: override the default splice_read callback on trace_pipe
 357  * @selftest: selftest to run on boot (see trace_selftest.c)
 358  * @print_headers: override the first lines that describe your columns
 359  * @print_line: callback that prints a trace
 360  * @set_flag: signals one of your private flags changed (trace_options file)
 361  * @flags: your private flags
 362  */
 363 struct tracer {
 364         const char              *name;
 365         int                     (*init)(struct trace_array *tr);
 366         void                    (*reset)(struct trace_array *tr);
 367         void                    (*start)(struct trace_array *tr);
 368         void                    (*stop)(struct trace_array *tr);
 369         void                    (*open)(struct trace_iterator *iter);
 370         void                    (*pipe_open)(struct trace_iterator *iter);
 371         void                    (*wait_pipe)(struct trace_iterator *iter);
 372         void                    (*close)(struct trace_iterator *iter);
 373         ssize_t                 (*read)(struct trace_iterator *iter,
 374                                         struct file *filp, char __user *ubuf,
 375                                         size_t cnt, loff_t *ppos);
 376         ssize_t                 (*splice_read)(struct trace_iterator *iter,
 377                                                struct file *filp,
 378                                                loff_t *ppos,
 379                                                struct pipe_inode_info *pipe,
 380                                                size_t len,
 381                                                unsigned int flags);
 382 #ifdef CONFIG_FTRACE_STARTUP_TEST
 383         int                     (*selftest)(struct tracer *trace,
 384                                             struct trace_array *tr);
 385 #endif
 386         void                    (*print_header)(struct seq_file *m);
 387         enum print_line_t       (*print_line)(struct trace_iterator *iter);
 388         /* If you handled the flag setting, return 0 */
 389         int                     (*set_flag)(u32 old_flags, u32 bit, int set);
 390         struct tracer           *next;
 391         int                     print_max;
 392         struct tracer_flags     *flags;
 393         struct tracer_stat      *stats;
 394 };
 395
 396 struct trace_seq {
 397         unsigned char           buffer[PAGE_SIZE];
 398         unsigned int            len;
 399         unsigned int            readpos;
 400 };
 401
 402 static inline void
 403 trace_seq_init(struct trace_seq *s)
 404 {
 405         s->len = 0;
 406         s->readpos = 0;
 407 }
 408
 409
 410 #define TRACE_PIPE_ALL_CPU      -1
 411
 412 /*
 413  * Trace iterator - used by printout routines who present trace
 414  * results to users and which routines might sleep, etc:
 415  */
 416 struct trace_iterator {
 417         struct trace_array      *tr;
 418         struct tracer           *trace;
 419         void                    *private;
 420         int                     cpu_file;
 421         struct mutex            mutex;
 422         struct ring_buffer_iter *buffer_iter[NR_CPUS];
 423
 424         /* The below is zeroed out in pipe_read */
 425         struct trace_seq        seq;
 426         struct trace_entry      *ent;
 427         int                     cpu;
 428         u64                     ts;
 429
 430         unsigned long           iter_flags;
 431         loff_t                  pos;
 432         long                    idx;
 433
 434         cpumask_var_t           started;
 435 };
 436
 437 int tracer_init(struct tracer *t, struct trace_array *tr);
 438 int tracing_is_enabled(void);
 439 void trace_wake_up(void);
 440 void tracing_reset(struct trace_array *tr, int cpu);
 441 void tracing_reset_online_cpus(struct trace_array *tr);
 442 int tracing_open_generic(struct inode *inode, struct file *filp);
 443 struct dentry *tracing_init_dentry(void);
 444 void init_tracer_sysprof_debugfs(struct dentry *d_tracer);
 445
 446 struct ring_buffer_event;
 447
 448 struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
 449                                                     unsigned char type,
 450                                                     unsigned long len,
 451                                                     unsigned long flags,
 452                                                     int pc);
 453 void trace_buffer_unlock_commit(struct trace_array *tr,
 454                                 struct ring_buffer_event *event,
 455                                 unsigned long flags, int pc);
 456
 457 struct ring_buffer_event *
 458 trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
 459                                   unsigned long flags, int pc);
 460 void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
 461                                         unsigned long flags, int pc);
 462
 463 struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
 464                                                 struct trace_array_cpu *data);
 465
 466 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
 467                                           int *ent_cpu, u64 *ent_ts);
 468
 469 void tracing_generic_entry_update(struct trace_entry *entry,
 470                                   unsigned long flags,
 471                                   int pc);
 472
 473 void default_wait_pipe(struct trace_iterator *iter);
 474 void poll_wait_pipe(struct trace_iterator *iter);
 475
 476 void ftrace(struct trace_array *tr,
 477                             struct trace_array_cpu *data,
 478                             unsigned long ip,
 479                             unsigned long parent_ip,
 480                             unsigned long flags, int pc);
 481 void tracing_sched_switch_trace(struct trace_array *tr,
 482                                 struct task_struct *prev,
 483                                 struct task_struct *next,
 484                                 unsigned long flags, int pc);
 485 void tracing_record_cmdline(struct task_struct *tsk);
 486
 487 void tracing_sched_wakeup_trace(struct trace_array *tr,
 488                                 struct task_struct *wakee,
 489                                 struct task_struct *cur,
 490                                 unsigned long flags, int pc);
 491 void trace_special(struct trace_array *tr,
 492                    struct trace_array_cpu *data,
 493                    unsigned long arg1,
 494                    unsigned long arg2,
 495                    unsigned long arg3, int pc);
 496 void trace_function(struct trace_array *tr,
 497                     unsigned long ip,
 498                     unsigned long parent_ip,
 499                     unsigned long flags, int pc);
 500
 501 void trace_graph_return(struct ftrace_graph_ret *trace);
 502 int trace_graph_entry(struct ftrace_graph_ent *trace);
 503
 504 void tracing_start_cmdline_record(void);
 505 void tracing_stop_cmdline_record(void);
 506 void tracing_sched_switch_assign_trace(struct trace_array *tr);
 507 void tracing_stop_sched_switch_record(void);
 508 void tracing_start_sched_switch_record(void);
 509 int register_tracer(struct tracer *type);
 510 void unregister_tracer(struct tracer *type);
 511
 512 extern unsigned long nsecs_to_usecs(unsigned long nsecs);
 513
 514 extern unsigned long tracing_max_latency;
 515 extern unsigned long tracing_thresh;
 516
 517 void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
 518 void update_max_tr_single(struct trace_array *tr,
 519                           struct task_struct *tsk, int cpu);
 520
 521 void __trace_stack(struct trace_array *tr,
 522                    unsigned long flags,
 523                    int skip, int pc);
 524
 525 extern cycle_t ftrace_now(int cpu);
 526
 527 #ifdef CONFIG_CONTEXT_SWITCH_TRACER
 528 typedef void
 529 (*tracer_switch_func_t)(void *private,
 530                         void *__rq,
 531                         struct task_struct *prev,
 532                         struct task_struct *next);
 533
 534 struct tracer_switch_ops {
 535         tracer_switch_func_t            func;
 536         void                            *private;
 537         struct tracer_switch_ops        *next;
 538 };
 539 #endif /* CONFIG_CONTEXT_SWITCH_TRACER */
 540
 541 extern char *trace_find_cmdline(int pid);
 542
 543 #ifdef CONFIG_DYNAMIC_FTRACE
 544 extern unsigned long ftrace_update_tot_cnt;
 545 #define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
 546 extern int DYN_FTRACE_TEST_NAME(void);
 547 #endif
 548
 549 #ifdef CONFIG_FTRACE_STARTUP_TEST
 550 extern int trace_selftest_startup_function(struct tracer *trace,
 551                                            struct trace_array *tr);
 552 extern int trace_selftest_startup_function_graph(struct tracer *trace,
 553                                                  struct trace_array *tr);
 554 extern int trace_selftest_startup_irqsoff(struct tracer *trace,
 555                                           struct trace_array *tr);
 556 extern int trace_selftest_startup_preemptoff(struct tracer *trace,
 557                                              struct trace_array *tr);
 558 extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
 559                                                  struct trace_array *tr);
 560 extern int trace_selftest_startup_wakeup(struct tracer *trace,
 561                                          struct trace_array *tr);
 562 extern int trace_selftest_startup_nop(struct tracer *trace,
 563                                          struct trace_array *tr);
 564 extern int trace_selftest_startup_sched_switch(struct tracer *trace,
 565                                                struct trace_array *tr);
 566 extern int trace_selftest_startup_sysprof(struct tracer *trace,
 567                                                struct trace_array *tr);
 568 extern int trace_selftest_startup_branch(struct tracer *trace,
 569                                          struct trace_array *tr);
 570 #endif /* CONFIG_FTRACE_STARTUP_TEST */
 571
 572 extern void *head_page(struct trace_array_cpu *data);
 573 extern long ns2usecs(cycle_t nsec);
 574 extern int
 575 trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args);
 576
 577 extern unsigned long trace_flags;
 578
 579 /* Standard output formatting function used for function return traces */
 580 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 581 extern enum print_line_t print_graph_function(struct trace_iterator *iter);
 582
 583 #ifdef CONFIG_DYNAMIC_FTRACE
 584 /* TODO: make this variable */
 585 #define FTRACE_GRAPH_MAX_FUNCS          32
 586 extern int ftrace_graph_count;
 587 extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
 588
 589 static inline int ftrace_graph_addr(unsigned long addr)
 590 {
 591         int i;
 592
 593         if (!ftrace_graph_count || test_tsk_trace_graph(current))
 594                 return 1;
 595
 596         for (i = 0; i < ftrace_graph_count; i++) {
 597                 if (addr == ftrace_graph_funcs[i])
 598                         return 1;
 599         }
 600
 601         return 0;
 602 }
 603 #else
 604 static inline int ftrace_trace_addr(unsigned long addr)
 605 {
 606         return 1;
 607 }
 608 static inline int ftrace_graph_addr(unsigned long addr)
 609 {
 610         return 1;
 611 }
 612 #endif /* CONFIG_DYNAMIC_FTRACE */
 613
 614 #else /* CONFIG_FUNCTION_GRAPH_TRACER */
 615 static inline enum print_line_t
 616 print_graph_function(struct trace_iterator *iter)
 617 {
 618         return TRACE_TYPE_UNHANDLED;
 619 }
 620 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 621
 622 extern struct pid *ftrace_pid_trace;
 623
 624 static inline int ftrace_trace_task(struct task_struct *task)
 625 {
 626         if (!ftrace_pid_trace)
 627                 return 1;
 628
 629         return test_tsk_trace_trace(task);
 630 }
 631
 632 /*
 633  * trace_iterator_flags is an enumeration that defines bit
 634  * positions into trace_flags that controls the output.
 635  *
 636  * NOTE: These bits must match the trace_options array in
 637  *       trace.c.
 638  */
 639 enum trace_iterator_flags {
 640         TRACE_ITER_PRINT_PARENT         = 0x01,
 641         TRACE_ITER_SYM_OFFSET           = 0x02,
 642         TRACE_ITER_SYM_ADDR             = 0x04,
 643         TRACE_ITER_VERBOSE              = 0x08,
 644         TRACE_ITER_RAW                  = 0x10,
 645         TRACE_ITER_HEX                  = 0x20,
 646         TRACE_ITER_BIN                  = 0x40,
 647         TRACE_ITER_BLOCK                = 0x80,
 648         TRACE_ITER_STACKTRACE           = 0x100,
 649         TRACE_ITER_SCHED_TREE           = 0x200,
 650         TRACE_ITER_PRINTK               = 0x400,
 651         TRACE_ITER_PREEMPTONLY          = 0x800,
 652         TRACE_ITER_BRANCH               = 0x1000,
 653         TRACE_ITER_ANNOTATE             = 0x2000,
 654         TRACE_ITER_USERSTACKTRACE       = 0x4000,
 655         TRACE_ITER_SYM_USEROBJ          = 0x8000,
 656         TRACE_ITER_PRINTK_MSGONLY       = 0x10000,
 657         TRACE_ITER_CONTEXT_INFO         = 0x20000, /* Print pid/cpu/time */
 658         TRACE_ITER_LATENCY_FMT          = 0x40000,
 659 };
 660
 661 /*
 662  * TRACE_ITER_SYM_MASK masks the options in trace_flags that
 663  * control the output of kernel symbols.
 664  */
 665 #define TRACE_ITER_SYM_MASK \
 666         (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
 667
 668 extern struct tracer nop_trace;
 669
 670 /**
 671  * ftrace_preempt_disable - disable preemption scheduler safe
 672  *
 673  * When tracing can happen inside the scheduler, there exists
 674  * cases that the tracing might happen before the need_resched
 675  * flag is checked. If this happens and the tracer calls
 676  * preempt_enable (after a disable), a schedule might take place
 677  * causing an infinite recursion.
 678  *
 679  * To prevent this, we read the need_resched flag before
 680  * disabling preemption. When we want to enable preemption we
 681  * check the flag, if it is set, then we call preempt_enable_no_resched.
 682  * Otherwise, we call preempt_enable.
 683  *
 684  * The rational for doing the above is that if need_resched is set
 685  * and we have yet to reschedule, we are either in an atomic location
 686  * (where we do not need to check for scheduling) or we are inside
 687  * the scheduler and do not want to resched.
 688  */
 689 static inline int ftrace_preempt_disable(void)
 690 {
 691         int resched;
 692
 693         resched = need_resched();
 694         preempt_disable_notrace();
 695
 696         return resched;
 697 }
 698
 699 /**
 700  * ftrace_preempt_enable - enable preemption scheduler safe
 701  * @resched: the return value from ftrace_preempt_disable
 702  *
 703  * This is a scheduler safe way to enable preemption and not miss
 704  * any preemption checks. The disabled saved the state of preemption.
 705  * If resched is set, then we are either inside an atomic or
 706  * are inside the scheduler (we would have already scheduled
 707  * otherwise). In this case, we do not want to call normal
 708  * preempt_enable, but preempt_enable_no_resched instead.
 709  */
 710 static inline void ftrace_preempt_enable(int resched)
 711 {
 712         if (resched)
 713                 preempt_enable_no_resched_notrace();
 714         else
 715                 preempt_enable_notrace();
 716 }
 717
 718 #ifdef CONFIG_BRANCH_TRACER
 719 extern int enable_branch_tracing(struct trace_array *tr);
 720 extern void disable_branch_tracing(void);
 721 static inline int trace_branch_enable(struct trace_array *tr)
 722 {
 723         if (trace_flags & TRACE_ITER_BRANCH)
 724                 return enable_branch_tracing(tr);
 725         return 0;
 726 }
 727 static inline void trace_branch_disable(void)
 728 {
 729         /* due to races, always disable */
 730         disable_branch_tracing();
 731 }
 732 #else
 733 static inline int trace_branch_enable(struct trace_array *tr)
 734 {
 735         return 0;
 736 }
 737 static inline void trace_branch_disable(void)
 738 {
 739 }
 740 #endif /* CONFIG_BRANCH_TRACER */
 741
 742 /* trace event type bit fields, not numeric */
 743 enum {
 744         TRACE_EVENT_TYPE_PRINTF         = 1,
 745         TRACE_EVENT_TYPE_RAW            = 2,
 746 };
 747
 748 struct ftrace_event_call {
 749         char            *name;
 750         char            *system;
 751         struct dentry   *dir;
 752         int             enabled;
 753         int             (*regfunc)(void);
 754         void            (*unregfunc)(void);
 755         int             id;
 756         int             (*raw_init)(void);
 757         int             (*show_format)(struct trace_seq *s);
 758 };
 759
 760 void event_trace_printk(unsigned long ip, const char *fmt, ...);
 761 extern struct ftrace_event_call __start_ftrace_events[];
 762 extern struct ftrace_event_call __stop_ftrace_events[];
 763
 764 #endif /* _LINUX_KERNEL_TRACE_H */