linux/kernel/trace/trace.h
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   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/tracepoint.h>
  11#include <linux/ftrace.h>
  12#include <trace/boot.h>
  13#include <linux/kmemtrace.h>
  14
  15#include <linux/trace_seq.h>
  16#include <linux/ftrace_event.h>
  17
  18enum trace_type {
  19        __TRACE_FIRST_TYPE = 0,
  20
  21        TRACE_FN,
  22        TRACE_CTX,
  23        TRACE_WAKE,
  24        TRACE_STACK,
  25        TRACE_PRINT,
  26        TRACE_BPRINT,
  27        TRACE_SPECIAL,
  28        TRACE_MMIO_RW,
  29        TRACE_MMIO_MAP,
  30        TRACE_BRANCH,
  31        TRACE_BOOT_CALL,
  32        TRACE_BOOT_RET,
  33        TRACE_GRAPH_RET,
  34        TRACE_GRAPH_ENT,
  35        TRACE_USER_STACK,
  36        TRACE_HW_BRANCHES,
  37        TRACE_KMEM_ALLOC,
  38        TRACE_KMEM_FREE,
  39        TRACE_BLK,
  40
  41        __TRACE_LAST_TYPE,
  42};
  43
  44enum kmemtrace_type_id {
  45        KMEMTRACE_TYPE_KMALLOC = 0,     /* kmalloc() or kfree(). */
  46        KMEMTRACE_TYPE_CACHE,           /* kmem_cache_*(). */
  47        KMEMTRACE_TYPE_PAGES,           /* __get_free_pages() and friends. */
  48};
  49
  50extern struct tracer boot_tracer;
  51
  52#undef __field
  53#define __field(type, item)             type    item;
  54
  55#undef __field_struct
  56#define __field_struct(type, item)      __field(type, item)
  57
  58#undef __field_desc
  59#define __field_desc(type, container, item)
  60
  61#undef __array
  62#define __array(type, item, size)       type    item[size];
  63
  64#undef __array_desc
  65#define __array_desc(type, container, item, size)
  66
  67#undef __dynamic_array
  68#define __dynamic_array(type, item)     type    item[];
  69
  70#undef F_STRUCT
  71#define F_STRUCT(args...)               args
  72
  73#undef FTRACE_ENTRY
  74#define FTRACE_ENTRY(name, struct_name, id, tstruct, print)     \
  75        struct struct_name {                                    \
  76                struct trace_entry      ent;                    \
  77                tstruct                                         \
  78        }
  79
  80#undef TP_ARGS
  81#define TP_ARGS(args...)        args
  82
  83#undef FTRACE_ENTRY_DUP
  84#define FTRACE_ENTRY_DUP(name, name_struct, id, tstruct, printk)
  85
  86#include "trace_entries.h"
  87
  88/*
  89 * syscalls are special, and need special handling, this is why
  90 * they are not included in trace_entries.h
  91 */
  92struct syscall_trace_enter {
  93        struct trace_entry      ent;
  94        int                     nr;
  95        unsigned long           args[];
  96};
  97
  98struct syscall_trace_exit {
  99        struct trace_entry      ent;
 100        int                     nr;
 101        unsigned long           ret;
 102};
 103
 104/*
 105 * trace_flag_type is an enumeration that holds different
 106 * states when a trace occurs. These are:
 107 *  IRQS_OFF            - interrupts were disabled
 108 *  IRQS_NOSUPPORT      - arch does not support irqs_disabled_flags
 109 *  NEED_RESCHED        - reschedule is requested
 110 *  HARDIRQ             - inside an interrupt handler
 111 *  SOFTIRQ             - inside a softirq handler
 112 */
 113enum trace_flag_type {
 114        TRACE_FLAG_IRQS_OFF             = 0x01,
 115        TRACE_FLAG_IRQS_NOSUPPORT       = 0x02,
 116        TRACE_FLAG_NEED_RESCHED         = 0x04,
 117        TRACE_FLAG_HARDIRQ              = 0x08,
 118        TRACE_FLAG_SOFTIRQ              = 0x10,
 119};
 120
 121#define TRACE_BUF_SIZE          1024
 122
 123/*
 124 * The CPU trace array - it consists of thousands of trace entries
 125 * plus some other descriptor data: (for example which task started
 126 * the trace, etc.)
 127 */
 128struct trace_array_cpu {
 129        atomic_t                disabled;
 130        void                    *buffer_page;   /* ring buffer spare */
 131
 132        unsigned long           saved_latency;
 133        unsigned long           critical_start;
 134        unsigned long           critical_end;
 135        unsigned long           critical_sequence;
 136        unsigned long           nice;
 137        unsigned long           policy;
 138        unsigned long           rt_priority;
 139        unsigned long           skipped_entries;
 140        cycle_t                 preempt_timestamp;
 141        pid_t                   pid;
 142        uid_t                   uid;
 143        char                    comm[TASK_COMM_LEN];
 144};
 145
 146/*
 147 * The trace array - an array of per-CPU trace arrays. This is the
 148 * highest level data structure that individual tracers deal with.
 149 * They have on/off state as well:
 150 */
 151struct trace_array {
 152        struct ring_buffer      *buffer;
 153        unsigned long           entries;
 154        int                     cpu;
 155        cycle_t                 time_start;
 156        struct task_struct      *waiter;
 157        struct trace_array_cpu  *data[NR_CPUS];
 158};
 159
 160#define FTRACE_CMP_TYPE(var, type) \
 161        __builtin_types_compatible_p(typeof(var), type *)
 162
 163#undef IF_ASSIGN
 164#define IF_ASSIGN(var, entry, etype, id)                \
 165        if (FTRACE_CMP_TYPE(var, etype)) {              \
 166                var = (typeof(var))(entry);             \
 167                WARN_ON(id && (entry)->type != id);     \
 168                break;                                  \
 169        }
 170
 171/* Will cause compile errors if type is not found. */
 172extern void __ftrace_bad_type(void);
 173
 174/*
 175 * The trace_assign_type is a verifier that the entry type is
 176 * the same as the type being assigned. To add new types simply
 177 * add a line with the following format:
 178 *
 179 * IF_ASSIGN(var, ent, type, id);
 180 *
 181 *  Where "type" is the trace type that includes the trace_entry
 182 *  as the "ent" item. And "id" is the trace identifier that is
 183 *  used in the trace_type enum.
 184 *
 185 *  If the type can have more than one id, then use zero.
 186 */
 187#define trace_assign_type(var, ent)                                     \
 188        do {                                                            \
 189                IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN);     \
 190                IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);        \
 191                IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);   \
 192                IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
 193                IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);   \
 194                IF_ASSIGN(var, ent, struct bprint_entry, TRACE_BPRINT); \
 195                IF_ASSIGN(var, ent, struct special_entry, 0);           \
 196                IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,          \
 197                          TRACE_MMIO_RW);                               \
 198                IF_ASSIGN(var, ent, struct trace_mmiotrace_map,         \
 199                          TRACE_MMIO_MAP);                              \
 200                IF_ASSIGN(var, ent, struct trace_boot_call, TRACE_BOOT_CALL);\
 201                IF_ASSIGN(var, ent, struct trace_boot_ret, TRACE_BOOT_RET);\
 202                IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
 203                IF_ASSIGN(var, ent, struct ftrace_graph_ent_entry,      \
 204                          TRACE_GRAPH_ENT);             \
 205                IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,      \
 206                          TRACE_GRAPH_RET);             \
 207                IF_ASSIGN(var, ent, struct hw_branch_entry, TRACE_HW_BRANCHES);\
 208                IF_ASSIGN(var, ent, struct kmemtrace_alloc_entry,       \
 209                          TRACE_KMEM_ALLOC);    \
 210                IF_ASSIGN(var, ent, struct kmemtrace_free_entry,        \
 211                          TRACE_KMEM_FREE);     \
 212                __ftrace_bad_type();                                    \
 213        } while (0)
 214
 215/*
 216 * An option specific to a tracer. This is a boolean value.
 217 * The bit is the bit index that sets its value on the
 218 * flags value in struct tracer_flags.
 219 */
 220struct tracer_opt {
 221        const char      *name; /* Will appear on the trace_options file */
 222        u32             bit; /* Mask assigned in val field in tracer_flags */
 223};
 224
 225/*
 226 * The set of specific options for a tracer. Your tracer
 227 * have to set the initial value of the flags val.
 228 */
 229struct tracer_flags {
 230        u32                     val;
 231        struct tracer_opt       *opts;
 232};
 233
 234/* Makes more easy to define a tracer opt */
 235#define TRACER_OPT(s, b)        .name = #s, .bit = b
 236
 237
 238/**
 239 * struct tracer - a specific tracer and its callbacks to interact with debugfs
 240 * @name: the name chosen to select it on the available_tracers file
 241 * @init: called when one switches to this tracer (echo name > current_tracer)
 242 * @reset: called when one switches to another tracer
 243 * @start: called when tracing is unpaused (echo 1 > tracing_enabled)
 244 * @stop: called when tracing is paused (echo 0 > tracing_enabled)
 245 * @open: called when the trace file is opened
 246 * @pipe_open: called when the trace_pipe file is opened
 247 * @wait_pipe: override how the user waits for traces on trace_pipe
 248 * @close: called when the trace file is released
 249 * @read: override the default read callback on trace_pipe
 250 * @splice_read: override the default splice_read callback on trace_pipe
 251 * @selftest: selftest to run on boot (see trace_selftest.c)
 252 * @print_headers: override the first lines that describe your columns
 253 * @print_line: callback that prints a trace
 254 * @set_flag: signals one of your private flags changed (trace_options file)
 255 * @flags: your private flags
 256 */
 257struct tracer {
 258        const char              *name;
 259        int                     (*init)(struct trace_array *tr);
 260        void                    (*reset)(struct trace_array *tr);
 261        void                    (*start)(struct trace_array *tr);
 262        void                    (*stop)(struct trace_array *tr);
 263        void                    (*open)(struct trace_iterator *iter);
 264        void                    (*pipe_open)(struct trace_iterator *iter);
 265        void                    (*wait_pipe)(struct trace_iterator *iter);
 266        void                    (*close)(struct trace_iterator *iter);
 267        ssize_t                 (*read)(struct trace_iterator *iter,
 268                                        struct file *filp, char __user *ubuf,
 269                                        size_t cnt, loff_t *ppos);
 270        ssize_t                 (*splice_read)(struct trace_iterator *iter,
 271                                               struct file *filp,
 272                                               loff_t *ppos,
 273                                               struct pipe_inode_info *pipe,
 274                                               size_t len,
 275                                               unsigned int flags);
 276#ifdef CONFIG_FTRACE_STARTUP_TEST
 277        int                     (*selftest)(struct tracer *trace,
 278                                            struct trace_array *tr);
 279#endif
 280        void                    (*print_header)(struct seq_file *m);
 281        enum print_line_t       (*print_line)(struct trace_iterator *iter);
 282        /* If you handled the flag setting, return 0 */
 283        int                     (*set_flag)(u32 old_flags, u32 bit, int set);
 284        struct tracer           *next;
 285        int                     print_max;
 286        struct tracer_flags     *flags;
 287};
 288
 289
 290#define TRACE_PIPE_ALL_CPU      -1
 291
 292int tracer_init(struct tracer *t, struct trace_array *tr);
 293int tracing_is_enabled(void);
 294void trace_wake_up(void);
 295void tracing_reset(struct trace_array *tr, int cpu);
 296void tracing_reset_online_cpus(struct trace_array *tr);
 297void tracing_reset_current(int cpu);
 298void tracing_reset_current_online_cpus(void);
 299int tracing_open_generic(struct inode *inode, struct file *filp);
 300struct dentry *trace_create_file(const char *name,
 301                                 mode_t mode,
 302                                 struct dentry *parent,
 303                                 void *data,
 304                                 const struct file_operations *fops);
 305
 306struct dentry *tracing_init_dentry(void);
 307void init_tracer_sysprof_debugfs(struct dentry *d_tracer);
 308
 309struct ring_buffer_event;
 310
 311struct ring_buffer_event *
 312trace_buffer_lock_reserve(struct ring_buffer *buffer,
 313                          int type,
 314                          unsigned long len,
 315                          unsigned long flags,
 316                          int pc);
 317void trace_buffer_unlock_commit(struct ring_buffer *buffer,
 318                                struct ring_buffer_event *event,
 319                                unsigned long flags, int pc);
 320
 321struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
 322                                                struct trace_array_cpu *data);
 323
 324struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
 325                                          int *ent_cpu, u64 *ent_ts);
 326
 327void default_wait_pipe(struct trace_iterator *iter);
 328void poll_wait_pipe(struct trace_iterator *iter);
 329
 330void ftrace(struct trace_array *tr,
 331                            struct trace_array_cpu *data,
 332                            unsigned long ip,
 333                            unsigned long parent_ip,
 334                            unsigned long flags, int pc);
 335void tracing_sched_switch_trace(struct trace_array *tr,
 336                                struct task_struct *prev,
 337                                struct task_struct *next,
 338                                unsigned long flags, int pc);
 339
 340void tracing_sched_wakeup_trace(struct trace_array *tr,
 341                                struct task_struct *wakee,
 342                                struct task_struct *cur,
 343                                unsigned long flags, int pc);
 344void trace_special(struct trace_array *tr,
 345                   struct trace_array_cpu *data,
 346                   unsigned long arg1,
 347                   unsigned long arg2,
 348                   unsigned long arg3, int pc);
 349void trace_function(struct trace_array *tr,
 350                    unsigned long ip,
 351                    unsigned long parent_ip,
 352                    unsigned long flags, int pc);
 353
 354void trace_graph_return(struct ftrace_graph_ret *trace);
 355int trace_graph_entry(struct ftrace_graph_ent *trace);
 356void set_graph_array(struct trace_array *tr);
 357
 358void tracing_start_cmdline_record(void);
 359void tracing_stop_cmdline_record(void);
 360void tracing_sched_switch_assign_trace(struct trace_array *tr);
 361void tracing_stop_sched_switch_record(void);
 362void tracing_start_sched_switch_record(void);
 363int register_tracer(struct tracer *type);
 364void unregister_tracer(struct tracer *type);
 365int is_tracing_stopped(void);
 366
 367extern unsigned long nsecs_to_usecs(unsigned long nsecs);
 368
 369#ifdef CONFIG_TRACER_MAX_TRACE
 370extern unsigned long tracing_max_latency;
 371extern unsigned long tracing_thresh;
 372
 373void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
 374void update_max_tr_single(struct trace_array *tr,
 375                          struct task_struct *tsk, int cpu);
 376#endif /* CONFIG_TRACER_MAX_TRACE */
 377
 378#ifdef CONFIG_STACKTRACE
 379void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
 380                        int skip, int pc);
 381
 382void ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags,
 383                            int pc);
 384
 385void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 386                   int pc);
 387#else
 388static inline void ftrace_trace_stack(struct trace_array *tr,
 389                                      unsigned long flags, int skip, int pc)
 390{
 391}
 392
 393static inline void ftrace_trace_userstack(struct trace_array *tr,
 394                                          unsigned long flags, int pc)
 395{
 396}
 397
 398static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
 399                                 int skip, int pc)
 400{
 401}
 402#endif /* CONFIG_STACKTRACE */
 403
 404extern cycle_t ftrace_now(int cpu);
 405
 406extern void trace_find_cmdline(int pid, char comm[]);
 407
 408#ifdef CONFIG_DYNAMIC_FTRACE
 409extern unsigned long ftrace_update_tot_cnt;
 410#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
 411extern int DYN_FTRACE_TEST_NAME(void);
 412#endif
 413
 414extern int ring_buffer_expanded;
 415extern bool tracing_selftest_disabled;
 416DECLARE_PER_CPU(local_t, ftrace_cpu_disabled);
 417
 418#ifdef CONFIG_FTRACE_STARTUP_TEST
 419extern int trace_selftest_startup_function(struct tracer *trace,
 420                                           struct trace_array *tr);
 421extern int trace_selftest_startup_function_graph(struct tracer *trace,
 422                                                 struct trace_array *tr);
 423extern int trace_selftest_startup_irqsoff(struct tracer *trace,
 424                                          struct trace_array *tr);
 425extern int trace_selftest_startup_preemptoff(struct tracer *trace,
 426                                             struct trace_array *tr);
 427extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
 428                                                 struct trace_array *tr);
 429extern int trace_selftest_startup_wakeup(struct tracer *trace,
 430                                         struct trace_array *tr);
 431extern int trace_selftest_startup_nop(struct tracer *trace,
 432                                         struct trace_array *tr);
 433extern int trace_selftest_startup_sched_switch(struct tracer *trace,
 434                                               struct trace_array *tr);
 435extern int trace_selftest_startup_sysprof(struct tracer *trace,
 436                                               struct trace_array *tr);
 437extern int trace_selftest_startup_branch(struct tracer *trace,
 438                                         struct trace_array *tr);
 439extern int trace_selftest_startup_hw_branches(struct tracer *trace,
 440                                              struct trace_array *tr);
 441#endif /* CONFIG_FTRACE_STARTUP_TEST */
 442
 443extern void *head_page(struct trace_array_cpu *data);
 444extern unsigned long long ns2usecs(cycle_t nsec);
 445extern int
 446trace_vbprintk(unsigned long ip, const char *fmt, va_list args);
 447extern int
 448trace_vprintk(unsigned long ip, const char *fmt, va_list args);
 449extern int
 450trace_array_vprintk(struct trace_array *tr,
 451                    unsigned long ip, const char *fmt, va_list args);
 452int trace_array_printk(struct trace_array *tr,
 453                       unsigned long ip, const char *fmt, ...);
 454
 455extern unsigned long trace_flags;
 456
 457extern int trace_clock_id;
 458
 459/* Standard output formatting function used for function return traces */
 460#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 461extern enum print_line_t print_graph_function(struct trace_iterator *iter);
 462extern enum print_line_t
 463trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
 464
 465#ifdef CONFIG_DYNAMIC_FTRACE
 466/* TODO: make this variable */
 467#define FTRACE_GRAPH_MAX_FUNCS          32
 468extern int ftrace_graph_count;
 469extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
 470
 471static inline int ftrace_graph_addr(unsigned long addr)
 472{
 473        int i;
 474
 475        if (!ftrace_graph_count || test_tsk_trace_graph(current))
 476                return 1;
 477
 478        for (i = 0; i < ftrace_graph_count; i++) {
 479                if (addr == ftrace_graph_funcs[i])
 480                        return 1;
 481        }
 482
 483        return 0;
 484}
 485#else
 486static inline int ftrace_trace_addr(unsigned long addr)
 487{
 488        return 1;
 489}
 490static inline int ftrace_graph_addr(unsigned long addr)
 491{
 492        return 1;
 493}
 494#endif /* CONFIG_DYNAMIC_FTRACE */
 495#else /* CONFIG_FUNCTION_GRAPH_TRACER */
 496static inline enum print_line_t
 497print_graph_function(struct trace_iterator *iter)
 498{
 499        return TRACE_TYPE_UNHANDLED;
 500}
 501#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 502
 503extern struct pid *ftrace_pid_trace;
 504
 505#ifdef CONFIG_FUNCTION_TRACER
 506static inline int ftrace_trace_task(struct task_struct *task)
 507{
 508        if (!ftrace_pid_trace)
 509                return 1;
 510
 511        return test_tsk_trace_trace(task);
 512}
 513#else
 514static inline int ftrace_trace_task(struct task_struct *task)
 515{
 516        return 1;
 517}
 518#endif
 519
 520/*
 521 * struct trace_parser - servers for reading the user input separated by spaces
 522 * @cont: set if the input is not complete - no final space char was found
 523 * @buffer: holds the parsed user input
 524 * @idx: user input lenght
 525 * @size: buffer size
 526 */
 527struct trace_parser {
 528        bool            cont;
 529        char            *buffer;
 530        unsigned        idx;
 531        unsigned        size;
 532};
 533
 534static inline bool trace_parser_loaded(struct trace_parser *parser)
 535{
 536        return (parser->idx != 0);
 537}
 538
 539static inline bool trace_parser_cont(struct trace_parser *parser)
 540{
 541        return parser->cont;
 542}
 543
 544static inline void trace_parser_clear(struct trace_parser *parser)
 545{
 546        parser->cont = false;
 547        parser->idx = 0;
 548}
 549
 550extern int trace_parser_get_init(struct trace_parser *parser, int size);
 551extern void trace_parser_put(struct trace_parser *parser);
 552extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 553        size_t cnt, loff_t *ppos);
 554
 555/*
 556 * trace_iterator_flags is an enumeration that defines bit
 557 * positions into trace_flags that controls the output.
 558 *
 559 * NOTE: These bits must match the trace_options array in
 560 *       trace.c.
 561 */
 562enum trace_iterator_flags {
 563        TRACE_ITER_PRINT_PARENT         = 0x01,
 564        TRACE_ITER_SYM_OFFSET           = 0x02,
 565        TRACE_ITER_SYM_ADDR             = 0x04,
 566        TRACE_ITER_VERBOSE              = 0x08,
 567        TRACE_ITER_RAW                  = 0x10,
 568        TRACE_ITER_HEX                  = 0x20,
 569        TRACE_ITER_BIN                  = 0x40,
 570        TRACE_ITER_BLOCK                = 0x80,
 571        TRACE_ITER_STACKTRACE           = 0x100,
 572        TRACE_ITER_SCHED_TREE           = 0x200,
 573        TRACE_ITER_PRINTK               = 0x400,
 574        TRACE_ITER_PREEMPTONLY          = 0x800,
 575        TRACE_ITER_BRANCH               = 0x1000,
 576        TRACE_ITER_ANNOTATE             = 0x2000,
 577        TRACE_ITER_USERSTACKTRACE       = 0x4000,
 578        TRACE_ITER_SYM_USEROBJ          = 0x8000,
 579        TRACE_ITER_PRINTK_MSGONLY       = 0x10000,
 580        TRACE_ITER_CONTEXT_INFO         = 0x20000, /* Print pid/cpu/time */
 581        TRACE_ITER_LATENCY_FMT          = 0x40000,
 582        TRACE_ITER_SLEEP_TIME           = 0x80000,
 583        TRACE_ITER_GRAPH_TIME           = 0x100000,
 584};
 585
 586/*
 587 * TRACE_ITER_SYM_MASK masks the options in trace_flags that
 588 * control the output of kernel symbols.
 589 */
 590#define TRACE_ITER_SYM_MASK \
 591        (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
 592
 593extern struct tracer nop_trace;
 594
 595/**
 596 * ftrace_preempt_disable - disable preemption scheduler safe
 597 *
 598 * When tracing can happen inside the scheduler, there exists
 599 * cases that the tracing might happen before the need_resched
 600 * flag is checked. If this happens and the tracer calls
 601 * preempt_enable (after a disable), a schedule might take place
 602 * causing an infinite recursion.
 603 *
 604 * To prevent this, we read the need_resched flag before
 605 * disabling preemption. When we want to enable preemption we
 606 * check the flag, if it is set, then we call preempt_enable_no_resched.
 607 * Otherwise, we call preempt_enable.
 608 *
 609 * The rational for doing the above is that if need_resched is set
 610 * and we have yet to reschedule, we are either in an atomic location
 611 * (where we do not need to check for scheduling) or we are inside
 612 * the scheduler and do not want to resched.
 613 */
 614static inline int ftrace_preempt_disable(void)
 615{
 616        int resched;
 617
 618        resched = need_resched();
 619        preempt_disable_notrace();
 620
 621        return resched;
 622}
 623
 624/**
 625 * ftrace_preempt_enable - enable preemption scheduler safe
 626 * @resched: the return value from ftrace_preempt_disable
 627 *
 628 * This is a scheduler safe way to enable preemption and not miss
 629 * any preemption checks. The disabled saved the state of preemption.
 630 * If resched is set, then we are either inside an atomic or
 631 * are inside the scheduler (we would have already scheduled
 632 * otherwise). In this case, we do not want to call normal
 633 * preempt_enable, but preempt_enable_no_resched instead.
 634 */
 635static inline void ftrace_preempt_enable(int resched)
 636{
 637        if (resched)
 638                preempt_enable_no_resched_notrace();
 639        else
 640                preempt_enable_notrace();
 641}
 642
 643#ifdef CONFIG_BRANCH_TRACER
 644extern int enable_branch_tracing(struct trace_array *tr);
 645extern void disable_branch_tracing(void);
 646static inline int trace_branch_enable(struct trace_array *tr)
 647{
 648        if (trace_flags & TRACE_ITER_BRANCH)
 649                return enable_branch_tracing(tr);
 650        return 0;
 651}
 652static inline void trace_branch_disable(void)
 653{
 654        /* due to races, always disable */
 655        disable_branch_tracing();
 656}
 657#else
 658static inline int trace_branch_enable(struct trace_array *tr)
 659{
 660        return 0;
 661}
 662static inline void trace_branch_disable(void)
 663{
 664}
 665#endif /* CONFIG_BRANCH_TRACER */
 666
 667/* set ring buffers to default size if not already done so */
 668int tracing_update_buffers(void);
 669
 670/* trace event type bit fields, not numeric */
 671enum {
 672        TRACE_EVENT_TYPE_PRINTF         = 1,
 673        TRACE_EVENT_TYPE_RAW            = 2,
 674};
 675
 676struct ftrace_event_field {
 677        struct list_head        link;
 678        char                    *name;
 679        char                    *type;
 680        int                     filter_type;
 681        int                     offset;
 682        int                     size;
 683        int                     is_signed;
 684};
 685
 686struct event_filter {
 687        int                     n_preds;
 688        struct filter_pred      **preds;
 689        char                    *filter_string;
 690        bool                    no_reset;
 691};
 692
 693struct event_subsystem {
 694        struct list_head        list;
 695        const char              *name;
 696        struct dentry           *entry;
 697        struct event_filter     *filter;
 698        int                     nr_events;
 699};
 700
 701struct filter_pred;
 702
 703typedef int (*filter_pred_fn_t) (struct filter_pred *pred, void *event,
 704                                 int val1, int val2);
 705
 706struct filter_pred {
 707        filter_pred_fn_t fn;
 708        u64 val;
 709        char str_val[MAX_FILTER_STR_VAL];
 710        int str_len;
 711        char *field_name;
 712        int offset;
 713        int not;
 714        int op;
 715        int pop_n;
 716};
 717
 718extern void print_event_filter(struct ftrace_event_call *call,
 719                               struct trace_seq *s);
 720extern int apply_event_filter(struct ftrace_event_call *call,
 721                              char *filter_string);
 722extern int apply_subsystem_event_filter(struct event_subsystem *system,
 723                                        char *filter_string);
 724extern void print_subsystem_event_filter(struct event_subsystem *system,
 725                                         struct trace_seq *s);
 726extern int filter_assign_type(const char *type);
 727
 728static inline int
 729filter_check_discard(struct ftrace_event_call *call, void *rec,
 730                     struct ring_buffer *buffer,
 731                     struct ring_buffer_event *event)
 732{
 733        if (unlikely(call->filter_active) && !filter_match_preds(call, rec)) {
 734                ring_buffer_discard_commit(buffer, event);
 735                return 1;
 736        }
 737
 738        return 0;
 739}
 740
 741extern struct mutex event_mutex;
 742extern struct list_head ftrace_events;
 743
 744extern const char *__start___trace_bprintk_fmt[];
 745extern const char *__stop___trace_bprintk_fmt[];
 746
 747#undef FTRACE_ENTRY
 748#define FTRACE_ENTRY(call, struct_name, id, tstruct, print)             \
 749        extern struct ftrace_event_call event_##call;
 750#undef FTRACE_ENTRY_DUP
 751#define FTRACE_ENTRY_DUP(call, struct_name, id, tstruct, print)         \
 752        FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
 753#include "trace_entries.h"
 754
 755#endif /* _LINUX_KERNEL_TRACE_H */
 756