1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 #ifndef _LINUX_KPROBES_H 3 #define _LINUX_KPROBES_H 4 /* 5 * Kernel Probes (KProbes) 6 * 7 * Copyright (C) IBM Corporation, 2002, 2004 8 * 9 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel 10 * Probes initial implementation ( includes suggestions from 11 * Rusty Russell). 12 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes 13 * interface to access function arguments. 14 * 2005-May Hien Nguyen <hien@us.ibm.com> and Jim Keniston 15 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi 16 * <prasanna@in.ibm.com> added function-return probes. 17 */ 18 #include <linux/compiler.h> 19 #include <linux/linkage.h> 20 #include <linux/list.h> 21 #include <linux/notifier.h> 22 #include <linux/smp.h> 23 #include <linux/bug.h> 24 #include <linux/percpu.h> 25 #include <linux/spinlock.h> 26 #include <linux/rcupdate.h> 27 #include <linux/mutex.h> 28 #include <linux/ftrace.h> 29 #include <linux/objpool.h> 30 #include <linux/rethook.h> 31 #include <asm/kprobes.h> 32 33 #ifdef CONFIG_KPROBES 34 35 /* kprobe_status settings */ 36 #define KPROBE_HIT_ACTIVE 0x00000001 37 #define KPROBE_HIT_SS 0x00000002 38 #define KPROBE_REENTER 0x00000004 39 #define KPROBE_HIT_SSDONE 0x00000008 40 41 #else /* !CONFIG_KPROBES */ 42 #include <asm-generic/kprobes.h> 43 typedef int kprobe_opcode_t; 44 struct arch_specific_insn { 45 int dummy; 46 }; 47 #endif /* CONFIG_KPROBES */ 48 49 struct kprobe; 50 struct pt_regs; 51 struct kretprobe; 52 struct kretprobe_instance; 53 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *); 54 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *, 55 unsigned long flags); 56 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *, 57 struct pt_regs *); 58 59 struct kprobe { 60 struct hlist_node hlist; 61 62 /* list of kprobes for multi-handler support */ 63 struct list_head list; 64 65 /*count the number of times this probe was temporarily disarmed */ 66 unsigned long nmissed; 67 68 /* location of the probe point */ 69 kprobe_opcode_t *addr; 70 71 /* Allow user to indicate symbol name of the probe point */ 72 const char *symbol_name; 73 74 /* Offset into the symbol */ 75 unsigned int offset; 76 77 /* Called before addr is executed. */ 78 kprobe_pre_handler_t pre_handler; 79 80 /* Called after addr is executed, unless... */ 81 kprobe_post_handler_t post_handler; 82 83 /* Saved opcode (which has been replaced with breakpoint) */ 84 kprobe_opcode_t opcode; 85 86 /* copy of the original instruction */ 87 struct arch_specific_insn ainsn; 88 89 /* 90 * Indicates various status flags. 91 * Protected by kprobe_mutex after this kprobe is registered. 92 */ 93 u32 flags; 94 }; 95 96 /* Kprobe status flags */ 97 #define KPROBE_FLAG_GONE 1 /* breakpoint has already gone */ 98 #define KPROBE_FLAG_DISABLED 2 /* probe is temporarily disabled */ 99 #define KPROBE_FLAG_OPTIMIZED 4 /* 100 * probe is really optimized. 101 * NOTE: 102 * this flag is only for optimized_kprobe. 103 */ 104 #define KPROBE_FLAG_FTRACE 8 /* probe is using ftrace */ 105 #define KPROBE_FLAG_ON_FUNC_ENTRY 16 /* probe is on the function entry */ 106 107 /* Has this kprobe gone ? */ 108 static inline bool kprobe_gone(struct kprobe *p) 109 { 110 return p->flags & KPROBE_FLAG_GONE; 111 } 112 113 /* Is this kprobe disabled ? */ 114 static inline bool kprobe_disabled(struct kprobe *p) 115 { 116 return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE); 117 } 118 119 /* Is this kprobe really running optimized path ? */ 120 static inline bool kprobe_optimized(struct kprobe *p) 121 { 122 return p->flags & KPROBE_FLAG_OPTIMIZED; 123 } 124 125 /* Is this kprobe uses ftrace ? */ 126 static inline bool kprobe_ftrace(struct kprobe *p) 127 { 128 return p->flags & KPROBE_FLAG_FTRACE; 129 } 130 131 /* 132 * Function-return probe - 133 * Note: 134 * User needs to provide a handler function, and initialize maxactive. 135 * maxactive - The maximum number of instances of the probed function that 136 * can be active concurrently. 137 * nmissed - tracks the number of times the probed function's return was 138 * ignored, due to maxactive being too low. 139 * 140 */ 141 struct kretprobe_holder { 142 struct kretprobe __rcu *rp; 143 struct objpool_head pool; 144 }; 145 146 struct kretprobe { 147 struct kprobe kp; 148 kretprobe_handler_t handler; 149 kretprobe_handler_t entry_handler; 150 int maxactive; 151 int nmissed; 152 size_t data_size; 153 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 154 struct rethook *rh; 155 #else 156 struct kretprobe_holder *rph; 157 #endif 158 }; 159 160 #define KRETPROBE_MAX_DATA_SIZE 4096 161 162 struct kretprobe_instance { 163 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 164 struct rethook_node node; 165 #else 166 struct rcu_head rcu; 167 struct llist_node llist; 168 struct kretprobe_holder *rph; 169 kprobe_opcode_t *ret_addr; 170 void *fp; 171 #endif 172 char data[]; 173 }; 174 175 struct kretprobe_blackpoint { 176 const char *name; 177 void *addr; 178 }; 179 180 struct kprobe_blacklist_entry { 181 struct list_head list; 182 unsigned long start_addr; 183 unsigned long end_addr; 184 }; 185 186 #ifdef CONFIG_KPROBES 187 DECLARE_PER_CPU(struct kprobe *, current_kprobe); 188 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 189 190 extern void kprobe_busy_begin(void); 191 extern void kprobe_busy_end(void); 192 193 #ifdef CONFIG_KRETPROBES 194 /* Check whether @p is used for implementing a trampoline. */ 195 extern int arch_trampoline_kprobe(struct kprobe *p); 196 197 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 198 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 199 { 200 /* rethook::data is non-changed field, so that you can access it freely. */ 201 return (struct kretprobe *)ri->node.rethook->data; 202 } 203 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 204 { 205 return ri->node.ret_addr; 206 } 207 #else 208 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 209 struct pt_regs *regs); 210 void arch_kretprobe_fixup_return(struct pt_regs *regs, 211 kprobe_opcode_t *correct_ret_addr); 212 213 void __kretprobe_trampoline(void); 214 /* 215 * Since some architecture uses structured function pointer, 216 * use dereference_function_descriptor() to get real function address. 217 */ 218 static nokprobe_inline void *kretprobe_trampoline_addr(void) 219 { 220 return dereference_kernel_function_descriptor(__kretprobe_trampoline); 221 } 222 223 /* If the trampoline handler called from a kprobe, use this version */ 224 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 225 void *frame_pointer); 226 227 static nokprobe_inline 228 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 229 void *frame_pointer) 230 { 231 unsigned long ret; 232 /* 233 * Set a dummy kprobe for avoiding kretprobe recursion. 234 * Since kretprobe never runs in kprobe handler, no kprobe must 235 * be running at this point. 236 */ 237 kprobe_busy_begin(); 238 ret = __kretprobe_trampoline_handler(regs, frame_pointer); 239 kprobe_busy_end(); 240 241 return ret; 242 } 243 244 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 245 { 246 return rcu_dereference_check(ri->rph->rp, rcu_read_lock_any_held()); 247 } 248 249 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 250 { 251 return (unsigned long)ri->ret_addr; 252 } 253 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */ 254 255 #else /* !CONFIG_KRETPROBES */ 256 static inline void arch_prepare_kretprobe(struct kretprobe *rp, 257 struct pt_regs *regs) 258 { 259 } 260 static inline int arch_trampoline_kprobe(struct kprobe *p) 261 { 262 return 0; 263 } 264 #endif /* CONFIG_KRETPROBES */ 265 266 /* Markers of '_kprobe_blacklist' section */ 267 extern unsigned long __start_kprobe_blacklist[]; 268 extern unsigned long __stop_kprobe_blacklist[]; 269 270 extern struct kretprobe_blackpoint kretprobe_blacklist[]; 271 272 extern int arch_prepare_kprobe(struct kprobe *p); 273 extern void arch_arm_kprobe(struct kprobe *p); 274 extern void arch_disarm_kprobe(struct kprobe *p); 275 extern int arch_init_kprobes(void); 276 extern void kprobes_inc_nmissed_count(struct kprobe *p); 277 extern bool arch_within_kprobe_blacklist(unsigned long addr); 278 extern int arch_populate_kprobe_blacklist(void); 279 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); 280 281 extern bool within_kprobe_blacklist(unsigned long addr); 282 extern int kprobe_add_ksym_blacklist(unsigned long entry); 283 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end); 284 285 struct kprobe_insn_cache { 286 struct mutex mutex; 287 void *(*alloc)(void); /* allocate insn page */ 288 void (*free)(void *); /* free insn page */ 289 const char *sym; /* symbol for insn pages */ 290 struct list_head pages; /* list of kprobe_insn_page */ 291 size_t insn_size; /* size of instruction slot */ 292 int nr_garbage; 293 }; 294 295 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 296 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c); 297 extern void __free_insn_slot(struct kprobe_insn_cache *c, 298 kprobe_opcode_t *slot, int dirty); 299 /* sleep-less address checking routine */ 300 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c, 301 unsigned long addr); 302 303 #define DEFINE_INSN_CACHE_OPS(__name) \ 304 extern struct kprobe_insn_cache kprobe_##__name##_slots; \ 305 \ 306 static inline kprobe_opcode_t *get_##__name##_slot(void) \ 307 { \ 308 return __get_insn_slot(&kprobe_##__name##_slots); \ 309 } \ 310 \ 311 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\ 312 { \ 313 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \ 314 } \ 315 \ 316 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 317 { \ 318 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \ 319 } 320 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page" 321 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page" 322 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, 323 unsigned long *value, char *type, char *sym); 324 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */ 325 #define DEFINE_INSN_CACHE_OPS(__name) \ 326 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 327 { \ 328 return 0; \ 329 } 330 #endif 331 332 DEFINE_INSN_CACHE_OPS(insn); 333 334 #ifdef CONFIG_OPTPROBES 335 /* 336 * Internal structure for direct jump optimized probe 337 */ 338 struct optimized_kprobe { 339 struct kprobe kp; 340 struct list_head list; /* list for optimizing queue */ 341 struct arch_optimized_insn optinsn; 342 }; 343 344 /* Architecture dependent functions for direct jump optimization */ 345 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); 346 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); 347 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, 348 struct kprobe *orig); 349 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); 350 extern void arch_optimize_kprobes(struct list_head *oplist); 351 extern void arch_unoptimize_kprobes(struct list_head *oplist, 352 struct list_head *done_list); 353 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); 354 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op, 355 kprobe_opcode_t *addr); 356 357 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 358 359 DEFINE_INSN_CACHE_OPS(optinsn); 360 361 extern void wait_for_kprobe_optimizer(void); 362 bool optprobe_queued_unopt(struct optimized_kprobe *op); 363 bool kprobe_disarmed(struct kprobe *p); 364 #else /* !CONFIG_OPTPROBES */ 365 static inline void wait_for_kprobe_optimizer(void) { } 366 #endif /* CONFIG_OPTPROBES */ 367 368 #ifdef CONFIG_KPROBES_ON_FTRACE 369 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 370 struct ftrace_ops *ops, struct ftrace_regs *fregs); 371 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 372 /* Set when ftrace has been killed: kprobes on ftrace must be disabled for safety */ 373 extern bool kprobe_ftrace_disabled __read_mostly; 374 extern void kprobe_ftrace_kill(void); 375 #else 376 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p) 377 { 378 return -EINVAL; 379 } 380 static inline void kprobe_ftrace_kill(void) {} 381 #endif /* CONFIG_KPROBES_ON_FTRACE */ 382 383 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 384 struct kprobe *get_kprobe(void *addr); 385 386 /* kprobe_running() will just return the current_kprobe on this CPU */ 387 static inline struct kprobe *kprobe_running(void) 388 { 389 return __this_cpu_read(current_kprobe); 390 } 391 392 static inline void reset_current_kprobe(void) 393 { 394 __this_cpu_write(current_kprobe, NULL); 395 } 396 397 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 398 { 399 return this_cpu_ptr(&kprobe_ctlblk); 400 } 401 402 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 403 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry); 404 405 int register_kprobe(struct kprobe *p); 406 void unregister_kprobe(struct kprobe *p); 407 int register_kprobes(struct kprobe **kps, int num); 408 void unregister_kprobes(struct kprobe **kps, int num); 409 410 int register_kretprobe(struct kretprobe *rp); 411 void unregister_kretprobe(struct kretprobe *rp); 412 int register_kretprobes(struct kretprobe **rps, int num); 413 void unregister_kretprobes(struct kretprobe **rps, int num); 414 415 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES) 416 #define kprobe_flush_task(tk) do {} while (0) 417 #else 418 void kprobe_flush_task(struct task_struct *tk); 419 #endif 420 421 void kprobe_free_init_mem(void); 422 423 int disable_kprobe(struct kprobe *kp); 424 int enable_kprobe(struct kprobe *kp); 425 426 void dump_kprobe(struct kprobe *kp); 427 428 void *alloc_insn_page(void); 429 430 void *alloc_optinsn_page(void); 431 void free_optinsn_page(void *page); 432 433 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 434 char *sym); 435 436 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 437 char *type, char *sym); 438 439 int kprobe_exceptions_notify(struct notifier_block *self, 440 unsigned long val, void *data); 441 442 #else /* !CONFIG_KPROBES: */ 443 444 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 445 { 446 return 0; 447 } 448 static inline struct kprobe *get_kprobe(void *addr) 449 { 450 return NULL; 451 } 452 static inline struct kprobe *kprobe_running(void) 453 { 454 return NULL; 455 } 456 #define kprobe_busy_begin() do {} while (0) 457 #define kprobe_busy_end() do {} while (0) 458 459 static inline int register_kprobe(struct kprobe *p) 460 { 461 return -EOPNOTSUPP; 462 } 463 static inline int register_kprobes(struct kprobe **kps, int num) 464 { 465 return -EOPNOTSUPP; 466 } 467 static inline void unregister_kprobe(struct kprobe *p) 468 { 469 } 470 static inline void unregister_kprobes(struct kprobe **kps, int num) 471 { 472 } 473 static inline int register_kretprobe(struct kretprobe *rp) 474 { 475 return -EOPNOTSUPP; 476 } 477 static inline int register_kretprobes(struct kretprobe **rps, int num) 478 { 479 return -EOPNOTSUPP; 480 } 481 static inline void unregister_kretprobe(struct kretprobe *rp) 482 { 483 } 484 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 485 { 486 } 487 static inline void kprobe_flush_task(struct task_struct *tk) 488 { 489 } 490 static inline void kprobe_free_init_mem(void) 491 { 492 } 493 static inline void kprobe_ftrace_kill(void) 494 { 495 } 496 static inline int disable_kprobe(struct kprobe *kp) 497 { 498 return -EOPNOTSUPP; 499 } 500 static inline int enable_kprobe(struct kprobe *kp) 501 { 502 return -EOPNOTSUPP; 503 } 504 505 static inline bool within_kprobe_blacklist(unsigned long addr) 506 { 507 return true; 508 } 509 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 510 char *type, char *sym) 511 { 512 return -ERANGE; 513 } 514 #endif /* CONFIG_KPROBES */ 515 516 static inline int disable_kretprobe(struct kretprobe *rp) 517 { 518 return disable_kprobe(&rp->kp); 519 } 520 static inline int enable_kretprobe(struct kretprobe *rp) 521 { 522 return enable_kprobe(&rp->kp); 523 } 524 525 #ifndef CONFIG_KPROBES 526 static inline bool is_kprobe_insn_slot(unsigned long addr) 527 { 528 return false; 529 } 530 #endif /* !CONFIG_KPROBES */ 531 532 #ifndef CONFIG_OPTPROBES 533 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 534 { 535 return false; 536 } 537 #endif /* !CONFIG_OPTPROBES */ 538 539 #ifdef CONFIG_KRETPROBES 540 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 541 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 542 { 543 return is_rethook_trampoline(addr); 544 } 545 546 static nokprobe_inline 547 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 548 struct llist_node **cur) 549 { 550 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur); 551 } 552 #else 553 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 554 { 555 return (void *)addr == kretprobe_trampoline_addr(); 556 } 557 558 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 559 struct llist_node **cur); 560 #endif 561 #else 562 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 563 { 564 return false; 565 } 566 567 static nokprobe_inline 568 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 569 struct llist_node **cur) 570 { 571 return 0; 572 } 573 #endif 574 575 /* Returns true if kprobes handled the fault */ 576 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 577 unsigned int trap) 578 { 579 if (!IS_ENABLED(CONFIG_KPROBES)) 580 return false; 581 if (user_mode(regs)) 582 return false; 583 /* 584 * To be potentially processing a kprobe fault and to be allowed 585 * to call kprobe_running(), we have to be non-preemptible. 586 */ 587 if (preemptible()) 588 return false; 589 if (!kprobe_running()) 590 return false; 591 return kprobe_fault_handler(regs, trap); 592 } 593 594 #endif /* _LINUX_KPROBES_H */ 595