include/linux/ftrace.h

   1 /*
   2  * Ftrace header.  For implementation details beyond the random comments
   3  * scattered below, see: Documentation/trace/ftrace-design.txt
   4  */
   5
   6 #ifndef _LINUX_FTRACE_H
   7 #define _LINUX_FTRACE_H
   8
   9 #include <linux/trace_clock.h>
  10 #include <linux/kallsyms.h>
  11 #include <linux/linkage.h>
  12 #include <linux/bitops.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/ktime.h>
  15 #include <linux/sched.h>
  16 #include <linux/types.h>
  17 #include <linux/init.h>
  18 #include <linux/fs.h>
  19
  20 #include <asm/ftrace.h>
  21
  22 /*
  23  * If the arch supports passing the variable contents of
  24  * function_trace_op as the third parameter back from the
  25  * mcount call, then the arch should define this as 1.
  26  */
  27 #ifndef ARCH_SUPPORTS_FTRACE_OPS
  28 #define ARCH_SUPPORTS_FTRACE_OPS 0
  29 #endif
  30
  31 /*
  32  * If the arch's mcount caller does not support all of ftrace's
  33  * features, then it must call an indirect function that
  34  * does. Or at least does enough to prevent any unwelcomed side effects.
  35  */
  36 #if !ARCH_SUPPORTS_FTRACE_OPS
  37 # define FTRACE_FORCE_LIST_FUNC 1
  38 #else
  39 # define FTRACE_FORCE_LIST_FUNC 0
  40 #endif
  41
  42 /* Main tracing buffer and events set up */
  43 #ifdef CONFIG_TRACING
  44 void trace_init(void);
  45 #else
  46 static inline void trace_init(void) { }
  47 #endif
  48
  49 struct module;
  50 struct ftrace_hash;
  51
  52 #ifdef CONFIG_FUNCTION_TRACER
  53
  54 extern int ftrace_enabled;
  55 extern int
  56 ftrace_enable_sysctl(struct ctl_table *table, int write,
  57                      void __user *buffer, size_t *lenp,
  58                      loff_t *ppos);
  59
  60 struct ftrace_ops;
  61
  62 typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
  63                               struct ftrace_ops *op, struct pt_regs *regs);
  64
  65 ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
  66
  67 /*
  68  * FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
  69  * set in the flags member.
  70  * CONTROL, SAVE_REGS, SAVE_REGS_IF_SUPPORTED, RECURSION_SAFE, STUB and
  71  * IPMODIFY are a kind of attribute flags which can be set only before
  72  * registering the ftrace_ops, and can not be modified while registered.
  73  * Changing those attribute flags after regsitering ftrace_ops will
  74  * cause unexpected results.
  75  *
  76  * ENABLED - set/unset when ftrace_ops is registered/unregistered
  77  * DYNAMIC - set when ftrace_ops is registered to denote dynamically
  78  *           allocated ftrace_ops which need special care
  79  * CONTROL - set manualy by ftrace_ops user to denote the ftrace_ops
  80  *           could be controled by following calls:
  81  *             ftrace_function_local_enable
  82  *             ftrace_function_local_disable
  83  * SAVE_REGS - The ftrace_ops wants regs saved at each function called
  84  *            and passed to the callback. If this flag is set, but the
  85  *            architecture does not support passing regs
  86  *            (CONFIG_DYNAMIC_FTRACE_WITH_REGS is not defined), then the
  87  *            ftrace_ops will fail to register, unless the next flag
  88  *            is set.
  89  * SAVE_REGS_IF_SUPPORTED - This is the same as SAVE_REGS, but if the
  90  *            handler can handle an arch that does not save regs
  91  *            (the handler tests if regs == NULL), then it can set
  92  *            this flag instead. It will not fail registering the ftrace_ops
  93  *            but, the regs field will be NULL if the arch does not support
  94  *            passing regs to the handler.
  95  *            Note, if this flag is set, the SAVE_REGS flag will automatically
  96  *            get set upon registering the ftrace_ops, if the arch supports it.
  97  * RECURSION_SAFE - The ftrace_ops can set this to tell the ftrace infrastructure
  98  *            that the call back has its own recursion protection. If it does
  99  *            not set this, then the ftrace infrastructure will add recursion
 100  *            protection for the caller.
 101  * STUB   - The ftrace_ops is just a place holder.
 102  * INITIALIZED - The ftrace_ops has already been initialized (first use time
 103  *            register_ftrace_function() is called, it will initialized the ops)
 104  * DELETED - The ops are being deleted, do not let them be registered again.
 105  * ADDING  - The ops is in the process of being added.
 106  * REMOVING - The ops is in the process of being removed.
 107  * MODIFYING - The ops is in the process of changing its filter functions.
 108  * ALLOC_TRAMP - A dynamic trampoline was allocated by the core code.
 109  *            The arch specific code sets this flag when it allocated a
 110  *            trampoline. This lets the arch know that it can update the
 111  *            trampoline in case the callback function changes.
 112  *            The ftrace_ops trampoline can be set by the ftrace users, and
 113  *            in such cases the arch must not modify it. Only the arch ftrace
 114  *            core code should set this flag.
 115  * IPMODIFY - The ops can modify the IP register. This can only be set with
 116  *            SAVE_REGS. If another ops with this flag set is already registered
 117  *            for any of the functions that this ops will be registered for, then
 118  *            this ops will fail to register or set_filter_ip.
 119  */
 120 enum {
 121         FTRACE_OPS_FL_ENABLED                   = 1 << 0,
 122         FTRACE_OPS_FL_DYNAMIC                   = 1 << 1,
 123         FTRACE_OPS_FL_CONTROL                   = 1 << 2,
 124         FTRACE_OPS_FL_SAVE_REGS                 = 1 << 3,
 125         FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED    = 1 << 4,
 126         FTRACE_OPS_FL_RECURSION_SAFE            = 1 << 5,
 127         FTRACE_OPS_FL_STUB                      = 1 << 6,
 128         FTRACE_OPS_FL_INITIALIZED               = 1 << 7,
 129         FTRACE_OPS_FL_DELETED                   = 1 << 8,
 130         FTRACE_OPS_FL_ADDING                    = 1 << 9,
 131         FTRACE_OPS_FL_REMOVING                  = 1 << 10,
 132         FTRACE_OPS_FL_MODIFYING                 = 1 << 11,
 133         FTRACE_OPS_FL_ALLOC_TRAMP               = 1 << 12,
 134         FTRACE_OPS_FL_IPMODIFY                  = 1 << 13,
 135 };
 136
 137 #ifdef CONFIG_DYNAMIC_FTRACE
 138 /* The hash used to know what functions callbacks trace */
 139 struct ftrace_ops_hash {
 140         struct ftrace_hash              *notrace_hash;
 141         struct ftrace_hash              *filter_hash;
 142         struct mutex                    regex_lock;
 143 };
 144 #endif
 145
 146 /*
 147  * Note, ftrace_ops can be referenced outside of RCU protection.
 148  * (Although, for perf, the control ops prevent that). If ftrace_ops is
 149  * allocated and not part of kernel core data, the unregistering of it will
 150  * perform a scheduling on all CPUs to make sure that there are no more users.
 151  * Depending on the load of the system that may take a bit of time.
 152  *
 153  * Any private data added must also take care not to be freed and if private
 154  * data is added to a ftrace_ops that is in core code, the user of the
 155  * ftrace_ops must perform a schedule_on_each_cpu() before freeing it.
 156  */
 157 struct ftrace_ops {
 158         ftrace_func_t                   func;
 159         struct ftrace_ops               *next;
 160         unsigned long                   flags;
 161         void                            *private;
 162         int __percpu                    *disabled;
 163 #ifdef CONFIG_DYNAMIC_FTRACE
 164         int                             nr_trampolines;
 165         struct ftrace_ops_hash          local_hash;
 166         struct ftrace_ops_hash          *func_hash;
 167         struct ftrace_ops_hash          old_hash;
 168         unsigned long                   trampoline;
 169         unsigned long                   trampoline_size;
 170 #endif
 171 };
 172
 173 /*
 174  * Type of the current tracing.
 175  */
 176 enum ftrace_tracing_type_t {
 177         FTRACE_TYPE_ENTER = 0, /* Hook the call of the function */
 178         FTRACE_TYPE_RETURN,     /* Hook the return of the function */
 179 };
 180
 181 /* Current tracing type, default is FTRACE_TYPE_ENTER */
 182 extern enum ftrace_tracing_type_t ftrace_tracing_type;
 183
 184 /*
 185  * The ftrace_ops must be a static and should also
 186  * be read_mostly.  These functions do modify read_mostly variables
 187  * so use them sparely. Never free an ftrace_op or modify the
 188  * next pointer after it has been registered. Even after unregistering
 189  * it, the next pointer may still be used internally.
 190  */
 191 int register_ftrace_function(struct ftrace_ops *ops);
 192 int unregister_ftrace_function(struct ftrace_ops *ops);
 193 void clear_ftrace_function(void);
 194
 195 /**
 196  * ftrace_function_local_enable - enable controlled ftrace_ops on current cpu
 197  *
 198  * This function enables tracing on current cpu by decreasing
 199  * the per cpu control variable.
 200  * It must be called with preemption disabled and only on ftrace_ops
 201  * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
 202  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 203  */
 204 static inline void ftrace_function_local_enable(struct ftrace_ops *ops)
 205 {
 206         if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
 207                 return;
 208
 209         (*this_cpu_ptr(ops->disabled))--;
 210 }
 211
 212 /**
 213  * ftrace_function_local_disable - enable controlled ftrace_ops on current cpu
 214  *
 215  * This function enables tracing on current cpu by decreasing
 216  * the per cpu control variable.
 217  * It must be called with preemption disabled and only on ftrace_ops
 218  * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
 219  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 220  */
 221 static inline void ftrace_function_local_disable(struct ftrace_ops *ops)
 222 {
 223         if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
 224                 return;
 225
 226         (*this_cpu_ptr(ops->disabled))++;
 227 }
 228
 229 /**
 230  * ftrace_function_local_disabled - returns ftrace_ops disabled value
 231  *                                  on current cpu
 232  *
 233  * This function returns value of ftrace_ops::disabled on current cpu.
 234  * It must be called with preemption disabled and only on ftrace_ops
 235  * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
 236  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 237  */
 238 static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
 239 {
 240         WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL));
 241         return *this_cpu_ptr(ops->disabled);
 242 }
 243
 244 extern void ftrace_stub(unsigned long a0, unsigned long a1,
 245                         struct ftrace_ops *op, struct pt_regs *regs);
 246
 247 #else /* !CONFIG_FUNCTION_TRACER */
 248 /*
 249  * (un)register_ftrace_function must be a macro since the ops parameter
 250  * must not be evaluated.
 251  */
 252 #define register_ftrace_function(ops) ({ 0; })
 253 #define unregister_ftrace_function(ops) ({ 0; })
 254 static inline int ftrace_nr_registered_ops(void)
 255 {
 256         return 0;
 257 }
 258 static inline void clear_ftrace_function(void) { }
 259 static inline void ftrace_kill(void) { }
 260 #endif /* CONFIG_FUNCTION_TRACER */
 261
 262 #ifdef CONFIG_STACK_TRACER
 263 extern int stack_tracer_enabled;
 264 int
 265 stack_trace_sysctl(struct ctl_table *table, int write,
 266                    void __user *buffer, size_t *lenp,
 267                    loff_t *ppos);
 268 #endif
 269
 270 struct ftrace_func_command {
 271         struct list_head        list;
 272         char                    *name;
 273         int                     (*func)(struct ftrace_hash *hash,
 274                                         char *func, char *cmd,
 275                                         char *params, int enable);
 276 };
 277
 278 #ifdef CONFIG_DYNAMIC_FTRACE
 279
 280 int ftrace_arch_code_modify_prepare(void);
 281 int ftrace_arch_code_modify_post_process(void);
 282
 283 struct dyn_ftrace;
 284
 285 void ftrace_bug(int err, struct dyn_ftrace *rec);
 286
 287 struct seq_file;
 288
 289 struct ftrace_probe_ops {
 290         void                    (*func)(unsigned long ip,
 291                                         unsigned long parent_ip,
 292                                         void **data);
 293         int                     (*init)(struct ftrace_probe_ops *ops,
 294                                         unsigned long ip, void **data);
 295         void                    (*free)(struct ftrace_probe_ops *ops,
 296                                         unsigned long ip, void **data);
 297         int                     (*print)(struct seq_file *m,
 298                                          unsigned long ip,
 299                                          struct ftrace_probe_ops *ops,
 300                                          void *data);
 301 };
 302
 303 extern int
 304 register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 305                               void *data);
 306 extern void
 307 unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 308                                 void *data);
 309 extern void
 310 unregister_ftrace_function_probe_func(char *glob, struct ftrace_probe_ops *ops);
 311 extern void unregister_ftrace_function_probe_all(char *glob);
 312
 313 extern int ftrace_text_reserved(const void *start, const void *end);
 314
 315 extern int ftrace_nr_registered_ops(void);
 316
 317 bool is_ftrace_trampoline(unsigned long addr);
 318
 319 /*
 320  * The dyn_ftrace record's flags field is split into two parts.
 321  * the first part which is '0-FTRACE_REF_MAX' is a counter of
 322  * the number of callbacks that have registered the function that
 323  * the dyn_ftrace descriptor represents.
 324  *
 325  * The second part is a mask:
 326  *  ENABLED - the function is being traced
 327  *  REGS    - the record wants the function to save regs
 328  *  REGS_EN - the function is set up to save regs.
 329  *  IPMODIFY - the record allows for the IP address to be changed.
 330  *
 331  * When a new ftrace_ops is registered and wants a function to save
 332  * pt_regs, the rec->flag REGS is set. When the function has been
 333  * set up to save regs, the REG_EN flag is set. Once a function
 334  * starts saving regs it will do so until all ftrace_ops are removed
 335  * from tracing that function.
 336  */
 337 enum {
 338         FTRACE_FL_ENABLED       = (1UL << 31),
 339         FTRACE_FL_REGS          = (1UL << 30),
 340         FTRACE_FL_REGS_EN       = (1UL << 29),
 341         FTRACE_FL_TRAMP         = (1UL << 28),
 342         FTRACE_FL_TRAMP_EN      = (1UL << 27),
 343         FTRACE_FL_IPMODIFY      = (1UL << 26),
 344 };
 345
 346 #define FTRACE_REF_MAX_SHIFT    26
 347 #define FTRACE_FL_BITS          6
 348 #define FTRACE_FL_MASKED_BITS   ((1UL << FTRACE_FL_BITS) - 1)
 349 #define FTRACE_FL_MASK          (FTRACE_FL_MASKED_BITS << FTRACE_REF_MAX_SHIFT)
 350 #define FTRACE_REF_MAX          ((1UL << FTRACE_REF_MAX_SHIFT) - 1)
 351
 352 #define ftrace_rec_count(rec)   ((rec)->flags & ~FTRACE_FL_MASK)
 353
 354 struct dyn_ftrace {
 355         unsigned long           ip; /* address of mcount call-site */
 356         unsigned long           flags;
 357         struct dyn_arch_ftrace  arch;
 358 };
 359
 360 int ftrace_force_update(void);
 361 int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
 362                          int remove, int reset);
 363 int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
 364                        int len, int reset);
 365 int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
 366                         int len, int reset);
 367 void ftrace_set_global_filter(unsigned char *buf, int len, int reset);
 368 void ftrace_set_global_notrace(unsigned char *buf, int len, int reset);
 369 void ftrace_free_filter(struct ftrace_ops *ops);
 370
 371 int register_ftrace_command(struct ftrace_func_command *cmd);
 372 int unregister_ftrace_command(struct ftrace_func_command *cmd);
 373
 374 enum {
 375         FTRACE_UPDATE_CALLS             = (1 << 0),
 376         FTRACE_DISABLE_CALLS            = (1 << 1),
 377         FTRACE_UPDATE_TRACE_FUNC        = (1 << 2),
 378         FTRACE_START_FUNC_RET           = (1 << 3),
 379         FTRACE_STOP_FUNC_RET            = (1 << 4),
 380 };
 381
 382 /*
 383  * The FTRACE_UPDATE_* enum is used to pass information back
 384  * from the ftrace_update_record() and ftrace_test_record()
 385  * functions. These are called by the code update routines
 386  * to find out what is to be done for a given function.
 387  *
 388  *  IGNORE           - The function is already what we want it to be
 389  *  MAKE_CALL        - Start tracing the function
 390  *  MODIFY_CALL      - Stop saving regs for the function
 391  *  MAKE_NOP         - Stop tracing the function
 392  */
 393 enum {
 394         FTRACE_UPDATE_IGNORE,
 395         FTRACE_UPDATE_MAKE_CALL,
 396         FTRACE_UPDATE_MODIFY_CALL,
 397         FTRACE_UPDATE_MAKE_NOP,
 398 };
 399
 400 enum {
 401         FTRACE_ITER_FILTER      = (1 << 0),
 402         FTRACE_ITER_NOTRACE     = (1 << 1),
 403         FTRACE_ITER_PRINTALL    = (1 << 2),
 404         FTRACE_ITER_DO_HASH     = (1 << 3),
 405         FTRACE_ITER_HASH        = (1 << 4),
 406         FTRACE_ITER_ENABLED     = (1 << 5),
 407 };
 408
 409 void arch_ftrace_update_code(int command);
 410
 411 struct ftrace_rec_iter;
 412
 413 struct ftrace_rec_iter *ftrace_rec_iter_start(void);
 414 struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter);
 415 struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter);
 416
 417 #define for_ftrace_rec_iter(iter)               \
 418         for (iter = ftrace_rec_iter_start();    \
 419              iter;                              \
 420              iter = ftrace_rec_iter_next(iter))
 421
 422
 423 int ftrace_update_record(struct dyn_ftrace *rec, int enable);
 424 int ftrace_test_record(struct dyn_ftrace *rec, int enable);
 425 void ftrace_run_stop_machine(int command);
 426 unsigned long ftrace_location(unsigned long ip);
 427 unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec);
 428 unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec);
 429
 430 extern ftrace_func_t ftrace_trace_function;
 431
 432 int ftrace_regex_open(struct ftrace_ops *ops, int flag,
 433                   struct inode *inode, struct file *file);
 434 ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
 435                             size_t cnt, loff_t *ppos);
 436 ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 437                              size_t cnt, loff_t *ppos);
 438 int ftrace_regex_release(struct inode *inode, struct file *file);
 439
 440 void __init
 441 ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable);
 442
 443 /* defined in arch */
 444 extern int ftrace_ip_converted(unsigned long ip);
 445 extern int ftrace_dyn_arch_init(void);
 446 extern void ftrace_replace_code(int enable);
 447 extern int ftrace_update_ftrace_func(ftrace_func_t func);
 448 extern void ftrace_caller(void);
 449 extern void ftrace_regs_caller(void);
 450 extern void ftrace_call(void);
 451 extern void ftrace_regs_call(void);
 452 extern void mcount_call(void);
 453
 454 void ftrace_modify_all_code(int command);
 455
 456 #ifndef FTRACE_ADDR
 457 #define FTRACE_ADDR ((unsigned long)ftrace_caller)
 458 #endif
 459
 460 #ifndef FTRACE_GRAPH_ADDR
 461 #define FTRACE_GRAPH_ADDR ((unsigned long)ftrace_graph_caller)
 462 #endif
 463
 464 #ifndef FTRACE_REGS_ADDR
 465 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 466 # define FTRACE_REGS_ADDR ((unsigned long)ftrace_regs_caller)
 467 #else
 468 # define FTRACE_REGS_ADDR FTRACE_ADDR
 469 #endif
 470 #endif
 471
 472 /*
 473  * If an arch would like functions that are only traced
 474  * by the function graph tracer to jump directly to its own
 475  * trampoline, then they can define FTRACE_GRAPH_TRAMP_ADDR
 476  * to be that address to jump to.
 477  */
 478 #ifndef FTRACE_GRAPH_TRAMP_ADDR
 479 #define FTRACE_GRAPH_TRAMP_ADDR ((unsigned long) 0)
 480 #endif
 481
 482 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 483 extern void ftrace_graph_caller(void);
 484 extern int ftrace_enable_ftrace_graph_caller(void);
 485 extern int ftrace_disable_ftrace_graph_caller(void);
 486 #else
 487 static inline int ftrace_enable_ftrace_graph_caller(void) { return 0; }
 488 static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; }
 489 #endif
 490
 491 /**
 492  * ftrace_make_nop - convert code into nop
 493  * @mod: module structure if called by module load initialization
 494  * @rec: the mcount call site record
 495  * @addr: the address that the call site should be calling
 496  *
 497  * This is a very sensitive operation and great care needs
 498  * to be taken by the arch.  The operation should carefully
 499  * read the location, check to see if what is read is indeed
 500  * what we expect it to be, and then on success of the compare,
 501  * it should write to the location.
 502  *
 503  * The code segment at @rec->ip should be a caller to @addr
 504  *
 505  * Return must be:
 506  *  0 on success
 507  *  -EFAULT on error reading the location
 508  *  -EINVAL on a failed compare of the contents
 509  *  -EPERM  on error writing to the location
 510  * Any other value will be considered a failure.
 511  */
 512 extern int ftrace_make_nop(struct module *mod,
 513                            struct dyn_ftrace *rec, unsigned long addr);
 514
 515 /**
 516  * ftrace_make_call - convert a nop call site into a call to addr
 517  * @rec: the mcount call site record
 518  * @addr: the address that the call site should call
 519  *
 520  * This is a very sensitive operation and great care needs
 521  * to be taken by the arch.  The operation should carefully
 522  * read the location, check to see if what is read is indeed
 523  * what we expect it to be, and then on success of the compare,
 524  * it should write to the location.
 525  *
 526  * The code segment at @rec->ip should be a nop
 527  *
 528  * Return must be:
 529  *  0 on success
 530  *  -EFAULT on error reading the location
 531  *  -EINVAL on a failed compare of the contents
 532  *  -EPERM  on error writing to the location
 533  * Any other value will be considered a failure.
 534  */
 535 extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
 536
 537 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 538 /**
 539  * ftrace_modify_call - convert from one addr to another (no nop)
 540  * @rec: the mcount call site record
 541  * @old_addr: the address expected to be currently called to
 542  * @addr: the address to change to
 543  *
 544  * This is a very sensitive operation and great care needs
 545  * to be taken by the arch.  The operation should carefully
 546  * read the location, check to see if what is read is indeed
 547  * what we expect it to be, and then on success of the compare,
 548  * it should write to the location.
 549  *
 550  * The code segment at @rec->ip should be a caller to @old_addr
 551  *
 552  * Return must be:
 553  *  0 on success
 554  *  -EFAULT on error reading the location
 555  *  -EINVAL on a failed compare of the contents
 556  *  -EPERM  on error writing to the location
 557  * Any other value will be considered a failure.
 558  */
 559 extern int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 560                               unsigned long addr);
 561 #else
 562 /* Should never be called */
 563 static inline int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 564                                      unsigned long addr)
 565 {
 566         return -EINVAL;
 567 }
 568 #endif
 569
 570 /* May be defined in arch */
 571 extern int ftrace_arch_read_dyn_info(char *buf, int size);
 572
 573 extern int skip_trace(unsigned long ip);
 574 extern void ftrace_module_init(struct module *mod);
 575
 576 extern void ftrace_disable_daemon(void);
 577 extern void ftrace_enable_daemon(void);
 578 #else /* CONFIG_DYNAMIC_FTRACE */
 579 static inline int skip_trace(unsigned long ip) { return 0; }
 580 static inline int ftrace_force_update(void) { return 0; }
 581 static inline void ftrace_disable_daemon(void) { }
 582 static inline void ftrace_enable_daemon(void) { }
 583 static inline void ftrace_release_mod(struct module *mod) {}
 584 static inline void ftrace_module_init(struct module *mod) {}
 585 static inline __init int register_ftrace_command(struct ftrace_func_command *cmd)
 586 {
 587         return -EINVAL;
 588 }
 589 static inline __init int unregister_ftrace_command(char *cmd_name)
 590 {
 591         return -EINVAL;
 592 }
 593 static inline int ftrace_text_reserved(const void *start, const void *end)
 594 {
 595         return 0;
 596 }
 597 static inline unsigned long ftrace_location(unsigned long ip)
 598 {
 599         return 0;
 600 }
 601
 602 /*
 603  * Again users of functions that have ftrace_ops may not
 604  * have them defined when ftrace is not enabled, but these
 605  * functions may still be called. Use a macro instead of inline.
 606  */
 607 #define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; })
 608 #define ftrace_set_early_filter(ops, buf, enable) do { } while (0)
 609 #define ftrace_set_filter_ip(ops, ip, remove, reset) ({ -ENODEV; })
 610 #define ftrace_set_filter(ops, buf, len, reset) ({ -ENODEV; })
 611 #define ftrace_set_notrace(ops, buf, len, reset) ({ -ENODEV; })
 612 #define ftrace_free_filter(ops) do { } while (0)
 613
 614 static inline ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
 615                             size_t cnt, loff_t *ppos) { return -ENODEV; }
 616 static inline ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 617                              size_t cnt, loff_t *ppos) { return -ENODEV; }
 618 static inline int
 619 ftrace_regex_release(struct inode *inode, struct file *file) { return -ENODEV; }
 620
 621 static inline bool is_ftrace_trampoline(unsigned long addr)
 622 {
 623         return false;
 624 }
 625 #endif /* CONFIG_DYNAMIC_FTRACE */
 626
 627 /* totally disable ftrace - can not re-enable after this */
 628 void ftrace_kill(void);
 629
 630 static inline void tracer_disable(void)
 631 {
 632 #ifdef CONFIG_FUNCTION_TRACER
 633         ftrace_enabled = 0;
 634 #endif
 635 }
 636
 637 /*
 638  * Ftrace disable/restore without lock. Some synchronization mechanism
 639  * must be used to prevent ftrace_enabled to be changed between
 640  * disable/restore.
 641  */
 642 static inline int __ftrace_enabled_save(void)
 643 {
 644 #ifdef CONFIG_FUNCTION_TRACER
 645         int saved_ftrace_enabled = ftrace_enabled;
 646         ftrace_enabled = 0;
 647         return saved_ftrace_enabled;
 648 #else
 649         return 0;
 650 #endif
 651 }
 652
 653 static inline void __ftrace_enabled_restore(int enabled)
 654 {
 655 #ifdef CONFIG_FUNCTION_TRACER
 656         ftrace_enabled = enabled;
 657 #endif
 658 }
 659
 660 /* All archs should have this, but we define it for consistency */
 661 #ifndef ftrace_return_address0
 662 # define ftrace_return_address0 __builtin_return_address(0)
 663 #endif
 664
 665 /* Archs may use other ways for ADDR1 and beyond */
 666 #ifndef ftrace_return_address
 667 # ifdef CONFIG_FRAME_POINTER
 668 #  define ftrace_return_address(n) __builtin_return_address(n)
 669 # else
 670 #  define ftrace_return_address(n) 0UL
 671 # endif
 672 #endif
 673
 674 #define CALLER_ADDR0 ((unsigned long)ftrace_return_address0)
 675 #define CALLER_ADDR1 ((unsigned long)ftrace_return_address(1))
 676 #define CALLER_ADDR2 ((unsigned long)ftrace_return_address(2))
 677 #define CALLER_ADDR3 ((unsigned long)ftrace_return_address(3))
 678 #define CALLER_ADDR4 ((unsigned long)ftrace_return_address(4))
 679 #define CALLER_ADDR5 ((unsigned long)ftrace_return_address(5))
 680 #define CALLER_ADDR6 ((unsigned long)ftrace_return_address(6))
 681
 682 #ifdef CONFIG_IRQSOFF_TRACER
 683   extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
 684   extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
 685 #else
 686   static inline void time_hardirqs_on(unsigned long a0, unsigned long a1) { }
 687   static inline void time_hardirqs_off(unsigned long a0, unsigned long a1) { }
 688 #endif
 689
 690 #ifdef CONFIG_PREEMPT_TRACER
 691   extern void trace_preempt_on(unsigned long a0, unsigned long a1);
 692   extern void trace_preempt_off(unsigned long a0, unsigned long a1);
 693 #else
 694 /*
 695  * Use defines instead of static inlines because some arches will make code out
 696  * of the CALLER_ADDR, when we really want these to be a real nop.
 697  */
 698 # define trace_preempt_on(a0, a1) do { } while (0)
 699 # define trace_preempt_off(a0, a1) do { } while (0)
 700 #endif
 701
 702 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 703 extern void ftrace_init(void);
 704 #else
 705 static inline void ftrace_init(void) { }
 706 #endif
 707
 708 /*
 709  * Structure that defines an entry function trace.
 710  */
 711 struct ftrace_graph_ent {
 712         unsigned long func; /* Current function */
 713         int depth;
 714 };
 715
 716 /*
 717  * Structure that defines a return function trace.
 718  */
 719 struct ftrace_graph_ret {
 720         unsigned long func; /* Current function */
 721         unsigned long long calltime;
 722         unsigned long long rettime;
 723         /* Number of functions that overran the depth limit for current task */
 724         unsigned long overrun;
 725         int depth;
 726 };
 727
 728 /* Type of the callback handlers for tracing function graph*/
 729 typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *); /* return */
 730 typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */
 731
 732 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 733
 734 /* for init task */
 735 #define INIT_FTRACE_GRAPH               .ret_stack = NULL,
 736
 737 /*
 738  * Stack of return addresses for functions
 739  * of a thread.
 740  * Used in struct thread_info
 741  */
 742 struct ftrace_ret_stack {
 743         unsigned long ret;
 744         unsigned long func;
 745         unsigned long long calltime;
 746         unsigned long long subtime;
 747         unsigned long fp;
 748 };
 749
 750 /*
 751  * Primary handler of a function return.
 752  * It relays on ftrace_return_to_handler.
 753  * Defined in entry_32/64.S
 754  */
 755 extern void return_to_handler(void);
 756
 757 extern int
 758 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
 759                          unsigned long frame_pointer);
 760
 761 /*
 762  * Sometimes we don't want to trace a function with the function
 763  * graph tracer but we want them to keep traced by the usual function
 764  * tracer if the function graph tracer is not configured.
 765  */
 766 #define __notrace_funcgraph             notrace
 767
 768 /*
 769  * We want to which function is an entrypoint of a hardirq.
 770  * That will help us to put a signal on output.
 771  */
 772 #define __irq_entry              __attribute__((__section__(".irqentry.text")))
 773
 774 /* Limits of hardirq entrypoints */
 775 extern char __irqentry_text_start[];
 776 extern char __irqentry_text_end[];
 777
 778 #define FTRACE_NOTRACE_DEPTH 65536
 779 #define FTRACE_RETFUNC_DEPTH 50
 780 #define FTRACE_RETSTACK_ALLOC_SIZE 32
 781 extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 782                                 trace_func_graph_ent_t entryfunc);
 783
 784 extern bool ftrace_graph_is_dead(void);
 785 extern void ftrace_graph_stop(void);
 786
 787 /* The current handlers in use */
 788 extern trace_func_graph_ret_t ftrace_graph_return;
 789 extern trace_func_graph_ent_t ftrace_graph_entry;
 790
 791 extern void unregister_ftrace_graph(void);
 792
 793 extern void ftrace_graph_init_task(struct task_struct *t);
 794 extern void ftrace_graph_exit_task(struct task_struct *t);
 795 extern void ftrace_graph_init_idle_task(struct task_struct *t, int cpu);
 796
 797 static inline int task_curr_ret_stack(struct task_struct *t)
 798 {
 799         return t->curr_ret_stack;
 800 }
 801
 802 static inline void pause_graph_tracing(void)
 803 {
 804         atomic_inc(&current->tracing_graph_pause);
 805 }
 806
 807 static inline void unpause_graph_tracing(void)
 808 {
 809         atomic_dec(&current->tracing_graph_pause);
 810 }
 811 #else /* !CONFIG_FUNCTION_GRAPH_TRACER */
 812
 813 #define __notrace_funcgraph
 814 #define __irq_entry
 815 #define INIT_FTRACE_GRAPH
 816
 817 static inline void ftrace_graph_init_task(struct task_struct *t) { }
 818 static inline void ftrace_graph_exit_task(struct task_struct *t) { }
 819 static inline void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) { }
 820
 821 static inline int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 822                           trace_func_graph_ent_t entryfunc)
 823 {
 824         return -1;
 825 }
 826 static inline void unregister_ftrace_graph(void) { }
 827
 828 static inline int task_curr_ret_stack(struct task_struct *tsk)
 829 {
 830         return -1;
 831 }
 832
 833 static inline void pause_graph_tracing(void) { }
 834 static inline void unpause_graph_tracing(void) { }
 835 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 836
 837 #ifdef CONFIG_TRACING
 838
 839 /* flags for current->trace */
 840 enum {
 841         TSK_TRACE_FL_TRACE_BIT  = 0,
 842         TSK_TRACE_FL_GRAPH_BIT  = 1,
 843 };
 844 enum {
 845         TSK_TRACE_FL_TRACE      = 1 << TSK_TRACE_FL_TRACE_BIT,
 846         TSK_TRACE_FL_GRAPH      = 1 << TSK_TRACE_FL_GRAPH_BIT,
 847 };
 848
 849 static inline void set_tsk_trace_trace(struct task_struct *tsk)
 850 {
 851         set_bit(TSK_TRACE_FL_TRACE_BIT, &tsk->trace);
 852 }
 853
 854 static inline void clear_tsk_trace_trace(struct task_struct *tsk)
 855 {
 856         clear_bit(TSK_TRACE_FL_TRACE_BIT, &tsk->trace);
 857 }
 858
 859 static inline int test_tsk_trace_trace(struct task_struct *tsk)
 860 {
 861         return tsk->trace & TSK_TRACE_FL_TRACE;
 862 }
 863
 864 static inline void set_tsk_trace_graph(struct task_struct *tsk)
 865 {
 866         set_bit(TSK_TRACE_FL_GRAPH_BIT, &tsk->trace);
 867 }
 868
 869 static inline void clear_tsk_trace_graph(struct task_struct *tsk)
 870 {
 871         clear_bit(TSK_TRACE_FL_GRAPH_BIT, &tsk->trace);
 872 }
 873
 874 static inline int test_tsk_trace_graph(struct task_struct *tsk)
 875 {
 876         return tsk->trace & TSK_TRACE_FL_GRAPH;
 877 }
 878
 879 enum ftrace_dump_mode;
 880
 881 extern enum ftrace_dump_mode ftrace_dump_on_oops;
 882
 883 extern void disable_trace_on_warning(void);
 884 extern int __disable_trace_on_warning;
 885
 886 #ifdef CONFIG_PREEMPT
 887 #define INIT_TRACE_RECURSION            .trace_recursion = 0,
 888 #endif
 889
 890 #else /* CONFIG_TRACING */
 891 static inline void  disable_trace_on_warning(void) { }
 892 #endif /* CONFIG_TRACING */
 893
 894 #ifndef INIT_TRACE_RECURSION
 895 #define INIT_TRACE_RECURSION
 896 #endif
 897
 898 #ifdef CONFIG_FTRACE_SYSCALLS
 899
 900 unsigned long arch_syscall_addr(int nr);
 901
 902 #endif /* CONFIG_FTRACE_SYSCALLS */
 903
 904 #endif /* _LINUX_FTRACE_H */