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 void early_trace_init(void);
  46 #else
  47 static inline void trace_init(void) { }
  48 static inline void early_trace_init(void) { }
  49 #endif
  50
  51 struct module;
  52 struct ftrace_hash;
  53
  54 #ifdef CONFIG_FUNCTION_TRACER
  55
  56 extern int ftrace_enabled;
  57 extern int
  58 ftrace_enable_sysctl(struct ctl_table *table, int write,
  59                      void __user *buffer, size_t *lenp,
  60                      loff_t *ppos);
  61
  62 struct ftrace_ops;
  63
  64 typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
  65                               struct ftrace_ops *op, struct pt_regs *regs);
  66
  67 ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
  68
  69 /*
  70  * FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
  71  * set in the flags member.
  72  * CONTROL, SAVE_REGS, SAVE_REGS_IF_SUPPORTED, RECURSION_SAFE, STUB and
  73  * IPMODIFY are a kind of attribute flags which can be set only before
  74  * registering the ftrace_ops, and can not be modified while registered.
  75  * Changing those attribute flags after registering ftrace_ops will
  76  * cause unexpected results.
  77  *
  78  * ENABLED - set/unset when ftrace_ops is registered/unregistered
  79  * DYNAMIC - set when ftrace_ops is registered to denote dynamically
  80  *           allocated ftrace_ops which need special care
  81  * PER_CPU - set manualy by ftrace_ops user to denote the ftrace_ops
  82  *           could be controlled by following calls:
  83  *             ftrace_function_local_enable
  84  *             ftrace_function_local_disable
  85  * SAVE_REGS - The ftrace_ops wants regs saved at each function called
  86  *            and passed to the callback. If this flag is set, but the
  87  *            architecture does not support passing regs
  88  *            (CONFIG_DYNAMIC_FTRACE_WITH_REGS is not defined), then the
  89  *            ftrace_ops will fail to register, unless the next flag
  90  *            is set.
  91  * SAVE_REGS_IF_SUPPORTED - This is the same as SAVE_REGS, but if the
  92  *            handler can handle an arch that does not save regs
  93  *            (the handler tests if regs == NULL), then it can set
  94  *            this flag instead. It will not fail registering the ftrace_ops
  95  *            but, the regs field will be NULL if the arch does not support
  96  *            passing regs to the handler.
  97  *            Note, if this flag is set, the SAVE_REGS flag will automatically
  98  *            get set upon registering the ftrace_ops, if the arch supports it.
  99  * RECURSION_SAFE - The ftrace_ops can set this to tell the ftrace infrastructure
 100  *            that the call back has its own recursion protection. If it does
 101  *            not set this, then the ftrace infrastructure will add recursion
 102  *            protection for the caller.
 103  * STUB   - The ftrace_ops is just a place holder.
 104  * INITIALIZED - The ftrace_ops has already been initialized (first use time
 105  *            register_ftrace_function() is called, it will initialized the ops)
 106  * DELETED - The ops are being deleted, do not let them be registered again.
 107  * ADDING  - The ops is in the process of being added.
 108  * REMOVING - The ops is in the process of being removed.
 109  * MODIFYING - The ops is in the process of changing its filter functions.
 110  * ALLOC_TRAMP - A dynamic trampoline was allocated by the core code.
 111  *            The arch specific code sets this flag when it allocated a
 112  *            trampoline. This lets the arch know that it can update the
 113  *            trampoline in case the callback function changes.
 114  *            The ftrace_ops trampoline can be set by the ftrace users, and
 115  *            in such cases the arch must not modify it. Only the arch ftrace
 116  *            core code should set this flag.
 117  * IPMODIFY - The ops can modify the IP register. This can only be set with
 118  *            SAVE_REGS. If another ops with this flag set is already registered
 119  *            for any of the functions that this ops will be registered for, then
 120  *            this ops will fail to register or set_filter_ip.
 121  * PID     - Is affected by set_ftrace_pid (allows filtering on those pids)
 122  */
 123 enum {
 124         FTRACE_OPS_FL_ENABLED                   = 1 << 0,
 125         FTRACE_OPS_FL_DYNAMIC                   = 1 << 1,
 126         FTRACE_OPS_FL_PER_CPU                   = 1 << 2,
 127         FTRACE_OPS_FL_SAVE_REGS                 = 1 << 3,
 128         FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED    = 1 << 4,
 129         FTRACE_OPS_FL_RECURSION_SAFE            = 1 << 5,
 130         FTRACE_OPS_FL_STUB                      = 1 << 6,
 131         FTRACE_OPS_FL_INITIALIZED               = 1 << 7,
 132         FTRACE_OPS_FL_DELETED                   = 1 << 8,
 133         FTRACE_OPS_FL_ADDING                    = 1 << 9,
 134         FTRACE_OPS_FL_REMOVING                  = 1 << 10,
 135         FTRACE_OPS_FL_MODIFYING                 = 1 << 11,
 136         FTRACE_OPS_FL_ALLOC_TRAMP               = 1 << 12,
 137         FTRACE_OPS_FL_IPMODIFY                  = 1 << 13,
 138         FTRACE_OPS_FL_PID                       = 1 << 14,
 139         FTRACE_OPS_FL_RCU                       = 1 << 15,
 140 };
 141
 142 #ifdef CONFIG_DYNAMIC_FTRACE
 143 /* The hash used to know what functions callbacks trace */
 144 struct ftrace_ops_hash {
 145         struct ftrace_hash              *notrace_hash;
 146         struct ftrace_hash              *filter_hash;
 147         struct mutex                    regex_lock;
 148 };
 149
 150 void ftrace_free_init_mem(void);
 151 #else
 152 static inline void ftrace_free_init_mem(void) { }
 153 #endif
 154
 155 /*
 156  * Note, ftrace_ops can be referenced outside of RCU protection, unless
 157  * the RCU flag is set. If ftrace_ops is allocated and not part of kernel
 158  * core data, the unregistering of it will perform a scheduling on all CPUs
 159  * to make sure that there are no more users. Depending on the load of the
 160  * system that may take a bit of time.
 161  *
 162  * Any private data added must also take care not to be freed and if private
 163  * data is added to a ftrace_ops that is in core code, the user of the
 164  * ftrace_ops must perform a schedule_on_each_cpu() before freeing it.
 165  */
 166 struct ftrace_ops {
 167         ftrace_func_t                   func;
 168         struct ftrace_ops               *next;
 169         unsigned long                   flags;
 170         void                            *private;
 171         ftrace_func_t                   saved_func;
 172         int __percpu                    *disabled;
 173 #ifdef CONFIG_DYNAMIC_FTRACE
 174         struct ftrace_ops_hash          local_hash;
 175         struct ftrace_ops_hash          *func_hash;
 176         struct ftrace_ops_hash          old_hash;
 177         unsigned long                   trampoline;
 178         unsigned long                   trampoline_size;
 179 #endif
 180 };
 181
 182 /*
 183  * Type of the current tracing.
 184  */
 185 enum ftrace_tracing_type_t {
 186         FTRACE_TYPE_ENTER = 0, /* Hook the call of the function */
 187         FTRACE_TYPE_RETURN,     /* Hook the return of the function */
 188 };
 189
 190 /* Current tracing type, default is FTRACE_TYPE_ENTER */
 191 extern enum ftrace_tracing_type_t ftrace_tracing_type;
 192
 193 /*
 194  * The ftrace_ops must be a static and should also
 195  * be read_mostly.  These functions do modify read_mostly variables
 196  * so use them sparely. Never free an ftrace_op or modify the
 197  * next pointer after it has been registered. Even after unregistering
 198  * it, the next pointer may still be used internally.
 199  */
 200 int register_ftrace_function(struct ftrace_ops *ops);
 201 int unregister_ftrace_function(struct ftrace_ops *ops);
 202 void clear_ftrace_function(void);
 203
 204 /**
 205  * ftrace_function_local_enable - enable ftrace_ops on current cpu
 206  *
 207  * This function enables tracing on current cpu by decreasing
 208  * the per cpu control variable.
 209  * It must be called with preemption disabled and only on ftrace_ops
 210  * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
 211  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 212  */
 213 static inline void ftrace_function_local_enable(struct ftrace_ops *ops)
 214 {
 215         if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
 216                 return;
 217
 218         (*this_cpu_ptr(ops->disabled))--;
 219 }
 220
 221 /**
 222  * ftrace_function_local_disable - disable ftrace_ops on current cpu
 223  *
 224  * This function disables tracing on current cpu by increasing
 225  * the per cpu control variable.
 226  * It must be called with preemption disabled and only on ftrace_ops
 227  * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
 228  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 229  */
 230 static inline void ftrace_function_local_disable(struct ftrace_ops *ops)
 231 {
 232         if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
 233                 return;
 234
 235         (*this_cpu_ptr(ops->disabled))++;
 236 }
 237
 238 /**
 239  * ftrace_function_local_disabled - returns ftrace_ops disabled value
 240  *                                  on current cpu
 241  *
 242  * This function returns value of ftrace_ops::disabled on current cpu.
 243  * It must be called with preemption disabled and only on ftrace_ops
 244  * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
 245  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 246  */
 247 static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
 248 {
 249         WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU));
 250         return *this_cpu_ptr(ops->disabled);
 251 }
 252
 253 extern void ftrace_stub(unsigned long a0, unsigned long a1,
 254                         struct ftrace_ops *op, struct pt_regs *regs);
 255
 256 #else /* !CONFIG_FUNCTION_TRACER */
 257 /*
 258  * (un)register_ftrace_function must be a macro since the ops parameter
 259  * must not be evaluated.
 260  */
 261 #define register_ftrace_function(ops) ({ 0; })
 262 #define unregister_ftrace_function(ops) ({ 0; })
 263 static inline int ftrace_nr_registered_ops(void)
 264 {
 265         return 0;
 266 }
 267 static inline void clear_ftrace_function(void) { }
 268 static inline void ftrace_kill(void) { }
 269 static inline void ftrace_free_init_mem(void) { }
 270 #endif /* CONFIG_FUNCTION_TRACER */
 271
 272 #ifdef CONFIG_STACK_TRACER
 273
 274 #define STACK_TRACE_ENTRIES 500
 275
 276 struct stack_trace;
 277
 278 extern unsigned stack_trace_index[];
 279 extern struct stack_trace stack_trace_max;
 280 extern unsigned long stack_trace_max_size;
 281 extern arch_spinlock_t stack_trace_max_lock;
 282
 283 extern int stack_tracer_enabled;
 284 void stack_trace_print(void);
 285 int
 286 stack_trace_sysctl(struct ctl_table *table, int write,
 287                    void __user *buffer, size_t *lenp,
 288                    loff_t *ppos);
 289
 290 /* DO NOT MODIFY THIS VARIABLE DIRECTLY! */
 291 DECLARE_PER_CPU(int, disable_stack_tracer);
 292
 293 /**
 294  * stack_tracer_disable - temporarily disable the stack tracer
 295  *
 296  * There's a few locations (namely in RCU) where stack tracing
 297  * cannot be executed. This function is used to disable stack
 298  * tracing during those critical sections.
 299  *
 300  * This function must be called with preemption or interrupts
 301  * disabled and stack_tracer_enable() must be called shortly after
 302  * while preemption or interrupts are still disabled.
 303  */
 304 static inline void stack_tracer_disable(void)
 305 {
 306         /* Preemption or interupts must be disabled */
 307         if (IS_ENABLED(CONFIG_PREEMPT_DEBUG))
 308                 WARN_ON_ONCE(!preempt_count() || !irqs_disabled());
 309         this_cpu_inc(disable_stack_tracer);
 310 }
 311
 312 /**
 313  * stack_tracer_enable - re-enable the stack tracer
 314  *
 315  * After stack_tracer_disable() is called, stack_tracer_enable()
 316  * must be called shortly afterward.
 317  */
 318 static inline void stack_tracer_enable(void)
 319 {
 320         if (IS_ENABLED(CONFIG_PREEMPT_DEBUG))
 321                 WARN_ON_ONCE(!preempt_count() || !irqs_disabled());
 322         this_cpu_dec(disable_stack_tracer);
 323 }
 324 #else
 325 static inline void stack_tracer_disable(void) { }
 326 static inline void stack_tracer_enable(void) { }
 327 #endif
 328
 329 #ifdef CONFIG_DYNAMIC_FTRACE
 330
 331 int ftrace_arch_code_modify_prepare(void);
 332 int ftrace_arch_code_modify_post_process(void);
 333
 334 struct dyn_ftrace;
 335
 336 enum ftrace_bug_type {
 337         FTRACE_BUG_UNKNOWN,
 338         FTRACE_BUG_INIT,
 339         FTRACE_BUG_NOP,
 340         FTRACE_BUG_CALL,
 341         FTRACE_BUG_UPDATE,
 342 };
 343 extern enum ftrace_bug_type ftrace_bug_type;
 344
 345 /*
 346  * Archs can set this to point to a variable that holds the value that was
 347  * expected at the call site before calling ftrace_bug().
 348  */
 349 extern const void *ftrace_expected;
 350
 351 void ftrace_bug(int err, struct dyn_ftrace *rec);
 352
 353 struct seq_file;
 354
 355 extern int ftrace_text_reserved(const void *start, const void *end);
 356
 357 extern int ftrace_nr_registered_ops(void);
 358
 359 bool is_ftrace_trampoline(unsigned long addr);
 360
 361 /*
 362  * The dyn_ftrace record's flags field is split into two parts.
 363  * the first part which is '0-FTRACE_REF_MAX' is a counter of
 364  * the number of callbacks that have registered the function that
 365  * the dyn_ftrace descriptor represents.
 366  *
 367  * The second part is a mask:
 368  *  ENABLED - the function is being traced
 369  *  REGS    - the record wants the function to save regs
 370  *  REGS_EN - the function is set up to save regs.
 371  *  IPMODIFY - the record allows for the IP address to be changed.
 372  *  DISABLED - the record is not ready to be touched yet
 373  *
 374  * When a new ftrace_ops is registered and wants a function to save
 375  * pt_regs, the rec->flag REGS is set. When the function has been
 376  * set up to save regs, the REG_EN flag is set. Once a function
 377  * starts saving regs it will do so until all ftrace_ops are removed
 378  * from tracing that function.
 379  */
 380 enum {
 381         FTRACE_FL_ENABLED       = (1UL << 31),
 382         FTRACE_FL_REGS          = (1UL << 30),
 383         FTRACE_FL_REGS_EN       = (1UL << 29),
 384         FTRACE_FL_TRAMP         = (1UL << 28),
 385         FTRACE_FL_TRAMP_EN      = (1UL << 27),
 386         FTRACE_FL_IPMODIFY      = (1UL << 26),
 387         FTRACE_FL_DISABLED      = (1UL << 25),
 388 };
 389
 390 #define FTRACE_REF_MAX_SHIFT    25
 391 #define FTRACE_FL_BITS          7
 392 #define FTRACE_FL_MASKED_BITS   ((1UL << FTRACE_FL_BITS) - 1)
 393 #define FTRACE_FL_MASK          (FTRACE_FL_MASKED_BITS << FTRACE_REF_MAX_SHIFT)
 394 #define FTRACE_REF_MAX          ((1UL << FTRACE_REF_MAX_SHIFT) - 1)
 395
 396 #define ftrace_rec_count(rec)   ((rec)->flags & ~FTRACE_FL_MASK)
 397
 398 struct dyn_ftrace {
 399         unsigned long           ip; /* address of mcount call-site */
 400         unsigned long           flags;
 401         struct dyn_arch_ftrace  arch;
 402 };
 403
 404 int ftrace_force_update(void);
 405 int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
 406                          int remove, int reset);
 407 int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
 408                        int len, int reset);
 409 int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
 410                         int len, int reset);
 411 void ftrace_set_global_filter(unsigned char *buf, int len, int reset);
 412 void ftrace_set_global_notrace(unsigned char *buf, int len, int reset);
 413 void ftrace_free_filter(struct ftrace_ops *ops);
 414 void ftrace_ops_set_global_filter(struct ftrace_ops *ops);
 415
 416 enum {
 417         FTRACE_UPDATE_CALLS             = (1 << 0),
 418         FTRACE_DISABLE_CALLS            = (1 << 1),
 419         FTRACE_UPDATE_TRACE_FUNC        = (1 << 2),
 420         FTRACE_START_FUNC_RET           = (1 << 3),
 421         FTRACE_STOP_FUNC_RET            = (1 << 4),
 422 };
 423
 424 /*
 425  * The FTRACE_UPDATE_* enum is used to pass information back
 426  * from the ftrace_update_record() and ftrace_test_record()
 427  * functions. These are called by the code update routines
 428  * to find out what is to be done for a given function.
 429  *
 430  *  IGNORE           - The function is already what we want it to be
 431  *  MAKE_CALL        - Start tracing the function
 432  *  MODIFY_CALL      - Stop saving regs for the function
 433  *  MAKE_NOP         - Stop tracing the function
 434  */
 435 enum {
 436         FTRACE_UPDATE_IGNORE,
 437         FTRACE_UPDATE_MAKE_CALL,
 438         FTRACE_UPDATE_MODIFY_CALL,
 439         FTRACE_UPDATE_MAKE_NOP,
 440 };
 441
 442 enum {
 443         FTRACE_ITER_FILTER      = (1 << 0),
 444         FTRACE_ITER_NOTRACE     = (1 << 1),
 445         FTRACE_ITER_PRINTALL    = (1 << 2),
 446         FTRACE_ITER_DO_PROBES   = (1 << 3),
 447         FTRACE_ITER_PROBE       = (1 << 4),
 448         FTRACE_ITER_ENABLED     = (1 << 5),
 449 };
 450
 451 void arch_ftrace_update_code(int command);
 452
 453 struct ftrace_rec_iter;
 454
 455 struct ftrace_rec_iter *ftrace_rec_iter_start(void);
 456 struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter);
 457 struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter);
 458
 459 #define for_ftrace_rec_iter(iter)               \
 460         for (iter = ftrace_rec_iter_start();    \
 461              iter;                              \
 462              iter = ftrace_rec_iter_next(iter))
 463
 464
 465 int ftrace_update_record(struct dyn_ftrace *rec, int enable);
 466 int ftrace_test_record(struct dyn_ftrace *rec, int enable);
 467 void ftrace_run_stop_machine(int command);
 468 unsigned long ftrace_location(unsigned long ip);
 469 unsigned long ftrace_location_range(unsigned long start, unsigned long end);
 470 unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec);
 471 unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec);
 472
 473 extern ftrace_func_t ftrace_trace_function;
 474
 475 int ftrace_regex_open(struct ftrace_ops *ops, int flag,
 476                   struct inode *inode, struct file *file);
 477 ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
 478                             size_t cnt, loff_t *ppos);
 479 ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 480                              size_t cnt, loff_t *ppos);
 481 int ftrace_regex_release(struct inode *inode, struct file *file);
 482
 483 void __init
 484 ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable);
 485
 486 /* defined in arch */
 487 extern int ftrace_ip_converted(unsigned long ip);
 488 extern int ftrace_dyn_arch_init(void);
 489 extern void ftrace_replace_code(int enable);
 490 extern int ftrace_update_ftrace_func(ftrace_func_t func);
 491 extern void ftrace_caller(void);
 492 extern void ftrace_regs_caller(void);
 493 extern void ftrace_call(void);
 494 extern void ftrace_regs_call(void);
 495 extern void mcount_call(void);
 496
 497 void ftrace_modify_all_code(int command);
 498
 499 #ifndef FTRACE_ADDR
 500 #define FTRACE_ADDR ((unsigned long)ftrace_caller)
 501 #endif
 502
 503 #ifndef FTRACE_GRAPH_ADDR
 504 #define FTRACE_GRAPH_ADDR ((unsigned long)ftrace_graph_caller)
 505 #endif
 506
 507 #ifndef FTRACE_REGS_ADDR
 508 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 509 # define FTRACE_REGS_ADDR ((unsigned long)ftrace_regs_caller)
 510 #else
 511 # define FTRACE_REGS_ADDR FTRACE_ADDR
 512 #endif
 513 #endif
 514
 515 /*
 516  * If an arch would like functions that are only traced
 517  * by the function graph tracer to jump directly to its own
 518  * trampoline, then they can define FTRACE_GRAPH_TRAMP_ADDR
 519  * to be that address to jump to.
 520  */
 521 #ifndef FTRACE_GRAPH_TRAMP_ADDR
 522 #define FTRACE_GRAPH_TRAMP_ADDR ((unsigned long) 0)
 523 #endif
 524
 525 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 526 extern void ftrace_graph_caller(void);
 527 extern int ftrace_enable_ftrace_graph_caller(void);
 528 extern int ftrace_disable_ftrace_graph_caller(void);
 529 #else
 530 static inline int ftrace_enable_ftrace_graph_caller(void) { return 0; }
 531 static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; }
 532 #endif
 533
 534 /**
 535  * ftrace_make_nop - convert code into nop
 536  * @mod: module structure if called by module load initialization
 537  * @rec: the mcount call site record
 538  * @addr: the address that the call site should be calling
 539  *
 540  * This is a very sensitive operation and great care needs
 541  * to be taken by the arch.  The operation should carefully
 542  * read the location, check to see if what is read is indeed
 543  * what we expect it to be, and then on success of the compare,
 544  * it should write to the location.
 545  *
 546  * The code segment at @rec->ip should be a caller to @addr
 547  *
 548  * Return must be:
 549  *  0 on success
 550  *  -EFAULT on error reading the location
 551  *  -EINVAL on a failed compare of the contents
 552  *  -EPERM  on error writing to the location
 553  * Any other value will be considered a failure.
 554  */
 555 extern int ftrace_make_nop(struct module *mod,
 556                            struct dyn_ftrace *rec, unsigned long addr);
 557
 558 /**
 559  * ftrace_make_call - convert a nop call site into a call to addr
 560  * @rec: the mcount call site record
 561  * @addr: the address that the call site should call
 562  *
 563  * This is a very sensitive operation and great care needs
 564  * to be taken by the arch.  The operation should carefully
 565  * read the location, check to see if what is read is indeed
 566  * what we expect it to be, and then on success of the compare,
 567  * it should write to the location.
 568  *
 569  * The code segment at @rec->ip should be a nop
 570  *
 571  * Return must be:
 572  *  0 on success
 573  *  -EFAULT on error reading the location
 574  *  -EINVAL on a failed compare of the contents
 575  *  -EPERM  on error writing to the location
 576  * Any other value will be considered a failure.
 577  */
 578 extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
 579
 580 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 581 /**
 582  * ftrace_modify_call - convert from one addr to another (no nop)
 583  * @rec: the mcount call site record
 584  * @old_addr: the address expected to be currently called to
 585  * @addr: the address to change to
 586  *
 587  * This is a very sensitive operation and great care needs
 588  * to be taken by the arch.  The operation should carefully
 589  * read the location, check to see if what is read is indeed
 590  * what we expect it to be, and then on success of the compare,
 591  * it should write to the location.
 592  *
 593  * The code segment at @rec->ip should be a caller to @old_addr
 594  *
 595  * Return must be:
 596  *  0 on success
 597  *  -EFAULT on error reading the location
 598  *  -EINVAL on a failed compare of the contents
 599  *  -EPERM  on error writing to the location
 600  * Any other value will be considered a failure.
 601  */
 602 extern int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 603                               unsigned long addr);
 604 #else
 605 /* Should never be called */
 606 static inline int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 607                                      unsigned long addr)
 608 {
 609         return -EINVAL;
 610 }
 611 #endif
 612
 613 /* May be defined in arch */
 614 extern int ftrace_arch_read_dyn_info(char *buf, int size);
 615
 616 extern int skip_trace(unsigned long ip);
 617 extern void ftrace_module_init(struct module *mod);
 618 extern void ftrace_module_enable(struct module *mod);
 619 extern void ftrace_release_mod(struct module *mod);
 620
 621 extern void ftrace_disable_daemon(void);
 622 extern void ftrace_enable_daemon(void);
 623 #else /* CONFIG_DYNAMIC_FTRACE */
 624 static inline int skip_trace(unsigned long ip) { return 0; }
 625 static inline int ftrace_force_update(void) { return 0; }
 626 static inline void ftrace_disable_daemon(void) { }
 627 static inline void ftrace_enable_daemon(void) { }
 628 static inline void ftrace_module_init(struct module *mod) { }
 629 static inline void ftrace_module_enable(struct module *mod) { }
 630 static inline void ftrace_release_mod(struct module *mod) { }
 631 static inline int ftrace_text_reserved(const void *start, const void *end)
 632 {
 633         return 0;
 634 }
 635 static inline unsigned long ftrace_location(unsigned long ip)
 636 {
 637         return 0;
 638 }
 639
 640 /*
 641  * Again users of functions that have ftrace_ops may not
 642  * have them defined when ftrace is not enabled, but these
 643  * functions may still be called. Use a macro instead of inline.
 644  */
 645 #define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; })
 646 #define ftrace_set_early_filter(ops, buf, enable) do { } while (0)
 647 #define ftrace_set_filter_ip(ops, ip, remove, reset) ({ -ENODEV; })
 648 #define ftrace_set_filter(ops, buf, len, reset) ({ -ENODEV; })
 649 #define ftrace_set_notrace(ops, buf, len, reset) ({ -ENODEV; })
 650 #define ftrace_free_filter(ops) do { } while (0)
 651 #define ftrace_ops_set_global_filter(ops) do { } while (0)
 652
 653 static inline ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
 654                             size_t cnt, loff_t *ppos) { return -ENODEV; }
 655 static inline ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 656                              size_t cnt, loff_t *ppos) { return -ENODEV; }
 657 static inline int
 658 ftrace_regex_release(struct inode *inode, struct file *file) { return -ENODEV; }
 659
 660 static inline bool is_ftrace_trampoline(unsigned long addr)
 661 {
 662         return false;
 663 }
 664 #endif /* CONFIG_DYNAMIC_FTRACE */
 665
 666 /* totally disable ftrace - can not re-enable after this */
 667 void ftrace_kill(void);
 668
 669 static inline void tracer_disable(void)
 670 {
 671 #ifdef CONFIG_FUNCTION_TRACER
 672         ftrace_enabled = 0;
 673 #endif
 674 }
 675
 676 /*
 677  * Ftrace disable/restore without lock. Some synchronization mechanism
 678  * must be used to prevent ftrace_enabled to be changed between
 679  * disable/restore.
 680  */
 681 static inline int __ftrace_enabled_save(void)
 682 {
 683 #ifdef CONFIG_FUNCTION_TRACER
 684         int saved_ftrace_enabled = ftrace_enabled;
 685         ftrace_enabled = 0;
 686         return saved_ftrace_enabled;
 687 #else
 688         return 0;
 689 #endif
 690 }
 691
 692 static inline void __ftrace_enabled_restore(int enabled)
 693 {
 694 #ifdef CONFIG_FUNCTION_TRACER
 695         ftrace_enabled = enabled;
 696 #endif
 697 }
 698
 699 /* All archs should have this, but we define it for consistency */
 700 #ifndef ftrace_return_address0
 701 # define ftrace_return_address0 __builtin_return_address(0)
 702 #endif
 703
 704 /* Archs may use other ways for ADDR1 and beyond */
 705 #ifndef ftrace_return_address
 706 # ifdef CONFIG_FRAME_POINTER
 707 #  define ftrace_return_address(n) __builtin_return_address(n)
 708 # else
 709 #  define ftrace_return_address(n) 0UL
 710 # endif
 711 #endif
 712
 713 #define CALLER_ADDR0 ((unsigned long)ftrace_return_address0)
 714 #define CALLER_ADDR1 ((unsigned long)ftrace_return_address(1))
 715 #define CALLER_ADDR2 ((unsigned long)ftrace_return_address(2))
 716 #define CALLER_ADDR3 ((unsigned long)ftrace_return_address(3))
 717 #define CALLER_ADDR4 ((unsigned long)ftrace_return_address(4))
 718 #define CALLER_ADDR5 ((unsigned long)ftrace_return_address(5))
 719 #define CALLER_ADDR6 ((unsigned long)ftrace_return_address(6))
 720
 721 static inline unsigned long get_lock_parent_ip(void)
 722 {
 723         unsigned long addr = CALLER_ADDR0;
 724
 725         if (!in_lock_functions(addr))
 726                 return addr;
 727         addr = CALLER_ADDR1;
 728         if (!in_lock_functions(addr))
 729                 return addr;
 730         return CALLER_ADDR2;
 731 }
 732
 733 #ifdef CONFIG_IRQSOFF_TRACER
 734   extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
 735   extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
 736 #else
 737   static inline void time_hardirqs_on(unsigned long a0, unsigned long a1) { }
 738   static inline void time_hardirqs_off(unsigned long a0, unsigned long a1) { }
 739 #endif
 740
 741 #ifdef CONFIG_PREEMPT_TRACER
 742   extern void trace_preempt_on(unsigned long a0, unsigned long a1);
 743   extern void trace_preempt_off(unsigned long a0, unsigned long a1);
 744 #else
 745 /*
 746  * Use defines instead of static inlines because some arches will make code out
 747  * of the CALLER_ADDR, when we really want these to be a real nop.
 748  */
 749 # define trace_preempt_on(a0, a1) do { } while (0)
 750 # define trace_preempt_off(a0, a1) do { } while (0)
 751 #endif
 752
 753 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 754 extern void ftrace_init(void);
 755 #else
 756 static inline void ftrace_init(void) { }
 757 #endif
 758
 759 /*
 760  * Structure that defines an entry function trace.
 761  * It's already packed but the attribute "packed" is needed
 762  * to remove extra padding at the end.
 763  */
 764 struct ftrace_graph_ent {
 765         unsigned long func; /* Current function */
 766         int depth;
 767 } __packed;
 768
 769 /*
 770  * Structure that defines a return function trace.
 771  * It's already packed but the attribute "packed" is needed
 772  * to remove extra padding at the end.
 773  */
 774 struct ftrace_graph_ret {
 775         unsigned long func; /* Current function */
 776         /* Number of functions that overran the depth limit for current task */
 777         unsigned long overrun;
 778         unsigned long long calltime;
 779         unsigned long long rettime;
 780         int depth;
 781 } __packed;
 782
 783 /* Type of the callback handlers for tracing function graph*/
 784 typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *); /* return */
 785 typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */
 786
 787 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 788
 789 /* for init task */
 790 #define INIT_FTRACE_GRAPH               .ret_stack = NULL,
 791
 792 /*
 793  * Stack of return addresses for functions
 794  * of a thread.
 795  * Used in struct thread_info
 796  */
 797 struct ftrace_ret_stack {
 798         unsigned long ret;
 799         unsigned long func;
 800         unsigned long long calltime;
 801 #ifdef CONFIG_FUNCTION_PROFILER
 802         unsigned long long subtime;
 803 #endif
 804 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
 805         unsigned long fp;
 806 #endif
 807 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 808         unsigned long *retp;
 809 #endif
 810 };
 811
 812 /*
 813  * Primary handler of a function return.
 814  * It relays on ftrace_return_to_handler.
 815  * Defined in entry_32/64.S
 816  */
 817 extern void return_to_handler(void);
 818
 819 extern int
 820 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
 821                          unsigned long frame_pointer, unsigned long *retp);
 822
 823 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
 824                                     unsigned long ret, unsigned long *retp);
 825
 826 /*
 827  * Sometimes we don't want to trace a function with the function
 828  * graph tracer but we want them to keep traced by the usual function
 829  * tracer if the function graph tracer is not configured.
 830  */
 831 #define __notrace_funcgraph             notrace
 832
 833 #define FTRACE_NOTRACE_DEPTH 65536
 834 #define FTRACE_RETFUNC_DEPTH 50
 835 #define FTRACE_RETSTACK_ALLOC_SIZE 32
 836 extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 837                                 trace_func_graph_ent_t entryfunc);
 838
 839 extern bool ftrace_graph_is_dead(void);
 840 extern void ftrace_graph_stop(void);
 841
 842 /* The current handlers in use */
 843 extern trace_func_graph_ret_t ftrace_graph_return;
 844 extern trace_func_graph_ent_t ftrace_graph_entry;
 845
 846 extern void unregister_ftrace_graph(void);
 847
 848 extern void ftrace_graph_init_task(struct task_struct *t);
 849 extern void ftrace_graph_exit_task(struct task_struct *t);
 850 extern void ftrace_graph_init_idle_task(struct task_struct *t, int cpu);
 851
 852 static inline int task_curr_ret_stack(struct task_struct *t)
 853 {
 854         return t->curr_ret_stack;
 855 }
 856
 857 static inline void pause_graph_tracing(void)
 858 {
 859         atomic_inc(&current->tracing_graph_pause);
 860 }
 861
 862 static inline void unpause_graph_tracing(void)
 863 {
 864         atomic_dec(&current->tracing_graph_pause);
 865 }
 866 #else /* !CONFIG_FUNCTION_GRAPH_TRACER */
 867
 868 #define __notrace_funcgraph
 869 #define INIT_FTRACE_GRAPH
 870
 871 static inline void ftrace_graph_init_task(struct task_struct *t) { }
 872 static inline void ftrace_graph_exit_task(struct task_struct *t) { }
 873 static inline void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) { }
 874
 875 static inline int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 876                           trace_func_graph_ent_t entryfunc)
 877 {
 878         return -1;
 879 }
 880 static inline void unregister_ftrace_graph(void) { }
 881
 882 static inline int task_curr_ret_stack(struct task_struct *tsk)
 883 {
 884         return -1;
 885 }
 886
 887 static inline unsigned long
 888 ftrace_graph_ret_addr(struct task_struct *task, int *idx, unsigned long ret,
 889                       unsigned long *retp)
 890 {
 891         return ret;
 892 }
 893
 894 static inline void pause_graph_tracing(void) { }
 895 static inline void unpause_graph_tracing(void) { }
 896 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 897
 898 #ifdef CONFIG_TRACING
 899
 900 /* flags for current->trace */
 901 enum {
 902         TSK_TRACE_FL_TRACE_BIT  = 0,
 903         TSK_TRACE_FL_GRAPH_BIT  = 1,
 904 };
 905 enum {
 906         TSK_TRACE_FL_TRACE      = 1 << TSK_TRACE_FL_TRACE_BIT,
 907         TSK_TRACE_FL_GRAPH      = 1 << TSK_TRACE_FL_GRAPH_BIT,
 908 };
 909
 910 static inline void set_tsk_trace_trace(struct task_struct *tsk)
 911 {
 912         set_bit(TSK_TRACE_FL_TRACE_BIT, &tsk->trace);
 913 }
 914
 915 static inline void clear_tsk_trace_trace(struct task_struct *tsk)
 916 {
 917         clear_bit(TSK_TRACE_FL_TRACE_BIT, &tsk->trace);
 918 }
 919
 920 static inline int test_tsk_trace_trace(struct task_struct *tsk)
 921 {
 922         return tsk->trace & TSK_TRACE_FL_TRACE;
 923 }
 924
 925 static inline void set_tsk_trace_graph(struct task_struct *tsk)
 926 {
 927         set_bit(TSK_TRACE_FL_GRAPH_BIT, &tsk->trace);
 928 }
 929
 930 static inline void clear_tsk_trace_graph(struct task_struct *tsk)
 931 {
 932         clear_bit(TSK_TRACE_FL_GRAPH_BIT, &tsk->trace);
 933 }
 934
 935 static inline int test_tsk_trace_graph(struct task_struct *tsk)
 936 {
 937         return tsk->trace & TSK_TRACE_FL_GRAPH;
 938 }
 939
 940 enum ftrace_dump_mode;
 941
 942 extern enum ftrace_dump_mode ftrace_dump_on_oops;
 943 extern int tracepoint_printk;
 944
 945 extern void disable_trace_on_warning(void);
 946 extern int __disable_trace_on_warning;
 947
 948 #ifdef CONFIG_PREEMPT
 949 #define INIT_TRACE_RECURSION            .trace_recursion = 0,
 950 #endif
 951
 952 int tracepoint_printk_sysctl(struct ctl_table *table, int write,
 953                              void __user *buffer, size_t *lenp,
 954                              loff_t *ppos);
 955
 956 #else /* CONFIG_TRACING */
 957 static inline void  disable_trace_on_warning(void) { }
 958 #endif /* CONFIG_TRACING */
 959
 960 #ifndef INIT_TRACE_RECURSION
 961 #define INIT_TRACE_RECURSION
 962 #endif
 963
 964 #ifdef CONFIG_FTRACE_SYSCALLS
 965
 966 unsigned long arch_syscall_addr(int nr);
 967
 968 #endif /* CONFIG_FTRACE_SYSCALLS */
 969
 970 #endif /* _LINUX_FTRACE_H */