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 #ifdef CONFIG_KPROBES_SANITY_TEST 273 extern int init_test_probes(void); 274 #else /* !CONFIG_KPROBES_SANITY_TEST */ 275 static inline int init_test_probes(void) 276 { 277 return 0; 278 } 279 #endif /* CONFIG_KPROBES_SANITY_TEST */ 280 281 extern int arch_prepare_kprobe(struct kprobe *p); 282 extern void arch_arm_kprobe(struct kprobe *p); 283 extern void arch_disarm_kprobe(struct kprobe *p); 284 extern int arch_init_kprobes(void); 285 extern void kprobes_inc_nmissed_count(struct kprobe *p); 286 extern bool arch_within_kprobe_blacklist(unsigned long addr); 287 extern int arch_populate_kprobe_blacklist(void); 288 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); 289 290 extern bool within_kprobe_blacklist(unsigned long addr); 291 extern int kprobe_add_ksym_blacklist(unsigned long entry); 292 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end); 293 294 struct kprobe_insn_cache { 295 struct mutex mutex; 296 void *(*alloc)(void); /* allocate insn page */ 297 void (*free)(void *); /* free insn page */ 298 const char *sym; /* symbol for insn pages */ 299 struct list_head pages; /* list of kprobe_insn_page */ 300 size_t insn_size; /* size of instruction slot */ 301 int nr_garbage; 302 }; 303 304 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 305 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c); 306 extern void __free_insn_slot(struct kprobe_insn_cache *c, 307 kprobe_opcode_t *slot, int dirty); 308 /* sleep-less address checking routine */ 309 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c, 310 unsigned long addr); 311 312 #define DEFINE_INSN_CACHE_OPS(__name) \ 313 extern struct kprobe_insn_cache kprobe_##__name##_slots; \ 314 \ 315 static inline kprobe_opcode_t *get_##__name##_slot(void) \ 316 { \ 317 return __get_insn_slot(&kprobe_##__name##_slots); \ 318 } \ 319 \ 320 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\ 321 { \ 322 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \ 323 } \ 324 \ 325 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 326 { \ 327 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \ 328 } 329 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page" 330 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page" 331 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, 332 unsigned long *value, char *type, char *sym); 333 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */ 334 #define DEFINE_INSN_CACHE_OPS(__name) \ 335 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 336 { \ 337 return 0; \ 338 } 339 #endif 340 341 DEFINE_INSN_CACHE_OPS(insn); 342 343 #ifdef CONFIG_OPTPROBES 344 /* 345 * Internal structure for direct jump optimized probe 346 */ 347 struct optimized_kprobe { 348 struct kprobe kp; 349 struct list_head list; /* list for optimizing queue */ 350 struct arch_optimized_insn optinsn; 351 }; 352 353 /* Architecture dependent functions for direct jump optimization */ 354 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); 355 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); 356 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, 357 struct kprobe *orig); 358 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); 359 extern void arch_optimize_kprobes(struct list_head *oplist); 360 extern void arch_unoptimize_kprobes(struct list_head *oplist, 361 struct list_head *done_list); 362 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); 363 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op, 364 kprobe_opcode_t *addr); 365 366 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 367 368 DEFINE_INSN_CACHE_OPS(optinsn); 369 370 extern void wait_for_kprobe_optimizer(void); 371 bool optprobe_queued_unopt(struct optimized_kprobe *op); 372 bool kprobe_disarmed(struct kprobe *p); 373 #else /* !CONFIG_OPTPROBES */ 374 static inline void wait_for_kprobe_optimizer(void) { } 375 #endif /* CONFIG_OPTPROBES */ 376 377 #ifdef CONFIG_KPROBES_ON_FTRACE 378 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 379 struct ftrace_ops *ops, struct ftrace_regs *fregs); 380 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 381 /* Set when ftrace has been killed: kprobes on ftrace must be disabled for safety */ 382 extern bool kprobe_ftrace_disabled __read_mostly; 383 extern void kprobe_ftrace_kill(void); 384 #else 385 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p) 386 { 387 return -EINVAL; 388 } 389 static inline void kprobe_ftrace_kill(void) {} 390 #endif /* CONFIG_KPROBES_ON_FTRACE */ 391 392 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 393 struct kprobe *get_kprobe(void *addr); 394 395 /* kprobe_running() will just return the current_kprobe on this CPU */ 396 static inline struct kprobe *kprobe_running(void) 397 { 398 return __this_cpu_read(current_kprobe); 399 } 400 401 static inline void reset_current_kprobe(void) 402 { 403 __this_cpu_write(current_kprobe, NULL); 404 } 405 406 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 407 { 408 return this_cpu_ptr(&kprobe_ctlblk); 409 } 410 411 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 412 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry); 413 414 int register_kprobe(struct kprobe *p); 415 void unregister_kprobe(struct kprobe *p); 416 int register_kprobes(struct kprobe **kps, int num); 417 void unregister_kprobes(struct kprobe **kps, int num); 418 419 int register_kretprobe(struct kretprobe *rp); 420 void unregister_kretprobe(struct kretprobe *rp); 421 int register_kretprobes(struct kretprobe **rps, int num); 422 void unregister_kretprobes(struct kretprobe **rps, int num); 423 424 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES) 425 #define kprobe_flush_task(tk) do {} while (0) 426 #else 427 void kprobe_flush_task(struct task_struct *tk); 428 #endif 429 430 void kprobe_free_init_mem(void); 431 432 int disable_kprobe(struct kprobe *kp); 433 int enable_kprobe(struct kprobe *kp); 434 435 void dump_kprobe(struct kprobe *kp); 436 437 void *alloc_insn_page(void); 438 439 void *alloc_optinsn_page(void); 440 void free_optinsn_page(void *page); 441 442 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 443 char *sym); 444 445 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 446 char *type, char *sym); 447 448 int kprobe_exceptions_notify(struct notifier_block *self, 449 unsigned long val, void *data); 450 451 #else /* !CONFIG_KPROBES: */ 452 453 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 454 { 455 return 0; 456 } 457 static inline struct kprobe *get_kprobe(void *addr) 458 { 459 return NULL; 460 } 461 static inline struct kprobe *kprobe_running(void) 462 { 463 return NULL; 464 } 465 #define kprobe_busy_begin() do {} while (0) 466 #define kprobe_busy_end() do {} while (0) 467 468 static inline int register_kprobe(struct kprobe *p) 469 { 470 return -EOPNOTSUPP; 471 } 472 static inline int register_kprobes(struct kprobe **kps, int num) 473 { 474 return -EOPNOTSUPP; 475 } 476 static inline void unregister_kprobe(struct kprobe *p) 477 { 478 } 479 static inline void unregister_kprobes(struct kprobe **kps, int num) 480 { 481 } 482 static inline int register_kretprobe(struct kretprobe *rp) 483 { 484 return -EOPNOTSUPP; 485 } 486 static inline int register_kretprobes(struct kretprobe **rps, int num) 487 { 488 return -EOPNOTSUPP; 489 } 490 static inline void unregister_kretprobe(struct kretprobe *rp) 491 { 492 } 493 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 494 { 495 } 496 static inline void kprobe_flush_task(struct task_struct *tk) 497 { 498 } 499 static inline void kprobe_free_init_mem(void) 500 { 501 } 502 static inline void kprobe_ftrace_kill(void) 503 { 504 } 505 static inline int disable_kprobe(struct kprobe *kp) 506 { 507 return -EOPNOTSUPP; 508 } 509 static inline int enable_kprobe(struct kprobe *kp) 510 { 511 return -EOPNOTSUPP; 512 } 513 514 static inline bool within_kprobe_blacklist(unsigned long addr) 515 { 516 return true; 517 } 518 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 519 char *type, char *sym) 520 { 521 return -ERANGE; 522 } 523 #endif /* CONFIG_KPROBES */ 524 525 static inline int disable_kretprobe(struct kretprobe *rp) 526 { 527 return disable_kprobe(&rp->kp); 528 } 529 static inline int enable_kretprobe(struct kretprobe *rp) 530 { 531 return enable_kprobe(&rp->kp); 532 } 533 534 #ifndef CONFIG_KPROBES 535 static inline bool is_kprobe_insn_slot(unsigned long addr) 536 { 537 return false; 538 } 539 #endif /* !CONFIG_KPROBES */ 540 541 #ifndef CONFIG_OPTPROBES 542 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 543 { 544 return false; 545 } 546 #endif /* !CONFIG_OPTPROBES */ 547 548 #ifdef CONFIG_KRETPROBES 549 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 550 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 551 { 552 return is_rethook_trampoline(addr); 553 } 554 555 static nokprobe_inline 556 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 557 struct llist_node **cur) 558 { 559 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur); 560 } 561 #else 562 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 563 { 564 return (void *)addr == kretprobe_trampoline_addr(); 565 } 566 567 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 568 struct llist_node **cur); 569 #endif 570 #else 571 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 572 { 573 return false; 574 } 575 576 static nokprobe_inline 577 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 578 struct llist_node **cur) 579 { 580 return 0; 581 } 582 #endif 583 584 /* Returns true if kprobes handled the fault */ 585 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 586 unsigned int trap) 587 { 588 if (!IS_ENABLED(CONFIG_KPROBES)) 589 return false; 590 if (user_mode(regs)) 591 return false; 592 /* 593 * To be potentially processing a kprobe fault and to be allowed 594 * to call kprobe_running(), we have to be non-preemptible. 595 */ 596 if (preemptible()) 597 return false; 598 if (!kprobe_running()) 599 return false; 600 return kprobe_fault_handler(regs, trap); 601 } 602 603 #endif /* _LINUX_KPROBES_H */ 604