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 *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 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 201 "Kretprobe is accessed from instance under preemptive context"); 202 203 return (struct kretprobe *)READ_ONCE(ri->node.rethook->data); 204 } 205 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 206 { 207 return ri->node.ret_addr; 208 } 209 #else 210 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 211 struct pt_regs *regs); 212 void arch_kretprobe_fixup_return(struct pt_regs *regs, 213 kprobe_opcode_t *correct_ret_addr); 214 215 void __kretprobe_trampoline(void); 216 /* 217 * Since some architecture uses structured function pointer, 218 * use dereference_function_descriptor() to get real function address. 219 */ 220 static nokprobe_inline void *kretprobe_trampoline_addr(void) 221 { 222 return dereference_kernel_function_descriptor(__kretprobe_trampoline); 223 } 224 225 /* If the trampoline handler called from a kprobe, use this version */ 226 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 227 void *frame_pointer); 228 229 static nokprobe_inline 230 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 231 void *frame_pointer) 232 { 233 unsigned long ret; 234 /* 235 * Set a dummy kprobe for avoiding kretprobe recursion. 236 * Since kretprobe never runs in kprobe handler, no kprobe must 237 * be running at this point. 238 */ 239 kprobe_busy_begin(); 240 ret = __kretprobe_trampoline_handler(regs, frame_pointer); 241 kprobe_busy_end(); 242 243 return ret; 244 } 245 246 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 247 { 248 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 249 "Kretprobe is accessed from instance under preemptive context"); 250 251 return READ_ONCE(ri->rph->rp); 252 } 253 254 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 255 { 256 return (unsigned long)ri->ret_addr; 257 } 258 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */ 259 260 #else /* !CONFIG_KRETPROBES */ 261 static inline void arch_prepare_kretprobe(struct kretprobe *rp, 262 struct pt_regs *regs) 263 { 264 } 265 static inline int arch_trampoline_kprobe(struct kprobe *p) 266 { 267 return 0; 268 } 269 #endif /* CONFIG_KRETPROBES */ 270 271 /* Markers of '_kprobe_blacklist' section */ 272 extern unsigned long __start_kprobe_blacklist[]; 273 extern unsigned long __stop_kprobe_blacklist[]; 274 275 extern struct kretprobe_blackpoint kretprobe_blacklist[]; 276 277 #ifdef CONFIG_KPROBES_SANITY_TEST 278 extern int init_test_probes(void); 279 #else /* !CONFIG_KPROBES_SANITY_TEST */ 280 static inline int init_test_probes(void) 281 { 282 return 0; 283 } 284 #endif /* CONFIG_KPROBES_SANITY_TEST */ 285 286 extern int arch_prepare_kprobe(struct kprobe *p); 287 extern void arch_arm_kprobe(struct kprobe *p); 288 extern void arch_disarm_kprobe(struct kprobe *p); 289 extern int arch_init_kprobes(void); 290 extern void kprobes_inc_nmissed_count(struct kprobe *p); 291 extern bool arch_within_kprobe_blacklist(unsigned long addr); 292 extern int arch_populate_kprobe_blacklist(void); 293 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); 294 295 extern bool within_kprobe_blacklist(unsigned long addr); 296 extern int kprobe_add_ksym_blacklist(unsigned long entry); 297 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end); 298 299 struct kprobe_insn_cache { 300 struct mutex mutex; 301 void *(*alloc)(void); /* allocate insn page */ 302 void (*free)(void *); /* free insn page */ 303 const char *sym; /* symbol for insn pages */ 304 struct list_head pages; /* list of kprobe_insn_page */ 305 size_t insn_size; /* size of instruction slot */ 306 int nr_garbage; 307 }; 308 309 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 310 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c); 311 extern void __free_insn_slot(struct kprobe_insn_cache *c, 312 kprobe_opcode_t *slot, int dirty); 313 /* sleep-less address checking routine */ 314 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c, 315 unsigned long addr); 316 317 #define DEFINE_INSN_CACHE_OPS(__name) \ 318 extern struct kprobe_insn_cache kprobe_##__name##_slots; \ 319 \ 320 static inline kprobe_opcode_t *get_##__name##_slot(void) \ 321 { \ 322 return __get_insn_slot(&kprobe_##__name##_slots); \ 323 } \ 324 \ 325 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\ 326 { \ 327 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \ 328 } \ 329 \ 330 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 331 { \ 332 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \ 333 } 334 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page" 335 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page" 336 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, 337 unsigned long *value, char *type, char *sym); 338 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */ 339 #define DEFINE_INSN_CACHE_OPS(__name) \ 340 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 341 { \ 342 return 0; \ 343 } 344 #endif 345 346 DEFINE_INSN_CACHE_OPS(insn); 347 348 #ifdef CONFIG_OPTPROBES 349 /* 350 * Internal structure for direct jump optimized probe 351 */ 352 struct optimized_kprobe { 353 struct kprobe kp; 354 struct list_head list; /* list for optimizing queue */ 355 struct arch_optimized_insn optinsn; 356 }; 357 358 /* Architecture dependent functions for direct jump optimization */ 359 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); 360 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); 361 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, 362 struct kprobe *orig); 363 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); 364 extern void arch_optimize_kprobes(struct list_head *oplist); 365 extern void arch_unoptimize_kprobes(struct list_head *oplist, 366 struct list_head *done_list); 367 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); 368 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op, 369 kprobe_opcode_t *addr); 370 371 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 372 373 DEFINE_INSN_CACHE_OPS(optinsn); 374 375 extern void wait_for_kprobe_optimizer(void); 376 bool optprobe_queued_unopt(struct optimized_kprobe *op); 377 bool kprobe_disarmed(struct kprobe *p); 378 #else /* !CONFIG_OPTPROBES */ 379 static inline void wait_for_kprobe_optimizer(void) { } 380 #endif /* CONFIG_OPTPROBES */ 381 382 #ifdef CONFIG_KPROBES_ON_FTRACE 383 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 384 struct ftrace_ops *ops, struct ftrace_regs *fregs); 385 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 386 #else 387 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p) 388 { 389 return -EINVAL; 390 } 391 #endif /* CONFIG_KPROBES_ON_FTRACE */ 392 393 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 394 struct kprobe *get_kprobe(void *addr); 395 396 /* kprobe_running() will just return the current_kprobe on this CPU */ 397 static inline struct kprobe *kprobe_running(void) 398 { 399 return __this_cpu_read(current_kprobe); 400 } 401 402 static inline void reset_current_kprobe(void) 403 { 404 __this_cpu_write(current_kprobe, NULL); 405 } 406 407 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 408 { 409 return this_cpu_ptr(&kprobe_ctlblk); 410 } 411 412 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 413 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry); 414 415 int register_kprobe(struct kprobe *p); 416 void unregister_kprobe(struct kprobe *p); 417 int register_kprobes(struct kprobe **kps, int num); 418 void unregister_kprobes(struct kprobe **kps, int num); 419 420 int register_kretprobe(struct kretprobe *rp); 421 void unregister_kretprobe(struct kretprobe *rp); 422 int register_kretprobes(struct kretprobe **rps, int num); 423 void unregister_kretprobes(struct kretprobe **rps, int num); 424 425 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES) 426 #define kprobe_flush_task(tk) do {} while (0) 427 #else 428 void kprobe_flush_task(struct task_struct *tk); 429 #endif 430 431 void kprobe_free_init_mem(void); 432 433 int disable_kprobe(struct kprobe *kp); 434 int enable_kprobe(struct kprobe *kp); 435 436 void dump_kprobe(struct kprobe *kp); 437 438 void *alloc_insn_page(void); 439 440 void *alloc_optinsn_page(void); 441 void free_optinsn_page(void *page); 442 443 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 444 char *sym); 445 446 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 447 char *type, char *sym); 448 449 int kprobe_exceptions_notify(struct notifier_block *self, 450 unsigned long val, void *data); 451 452 #else /* !CONFIG_KPROBES: */ 453 454 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 455 { 456 return 0; 457 } 458 static inline struct kprobe *get_kprobe(void *addr) 459 { 460 return NULL; 461 } 462 static inline struct kprobe *kprobe_running(void) 463 { 464 return NULL; 465 } 466 #define kprobe_busy_begin() do {} while (0) 467 #define kprobe_busy_end() do {} while (0) 468 469 static inline int register_kprobe(struct kprobe *p) 470 { 471 return -EOPNOTSUPP; 472 } 473 static inline int register_kprobes(struct kprobe **kps, int num) 474 { 475 return -EOPNOTSUPP; 476 } 477 static inline void unregister_kprobe(struct kprobe *p) 478 { 479 } 480 static inline void unregister_kprobes(struct kprobe **kps, int num) 481 { 482 } 483 static inline int register_kretprobe(struct kretprobe *rp) 484 { 485 return -EOPNOTSUPP; 486 } 487 static inline int register_kretprobes(struct kretprobe **rps, int num) 488 { 489 return -EOPNOTSUPP; 490 } 491 static inline void unregister_kretprobe(struct kretprobe *rp) 492 { 493 } 494 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 495 { 496 } 497 static inline void kprobe_flush_task(struct task_struct *tk) 498 { 499 } 500 static inline void kprobe_free_init_mem(void) 501 { 502 } 503 static inline int disable_kprobe(struct kprobe *kp) 504 { 505 return -EOPNOTSUPP; 506 } 507 static inline int enable_kprobe(struct kprobe *kp) 508 { 509 return -EOPNOTSUPP; 510 } 511 512 static inline bool within_kprobe_blacklist(unsigned long addr) 513 { 514 return true; 515 } 516 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 517 char *type, char *sym) 518 { 519 return -ERANGE; 520 } 521 #endif /* CONFIG_KPROBES */ 522 523 static inline int disable_kretprobe(struct kretprobe *rp) 524 { 525 return disable_kprobe(&rp->kp); 526 } 527 static inline int enable_kretprobe(struct kretprobe *rp) 528 { 529 return enable_kprobe(&rp->kp); 530 } 531 532 #ifndef CONFIG_KPROBES 533 static inline bool is_kprobe_insn_slot(unsigned long addr) 534 { 535 return false; 536 } 537 #endif /* !CONFIG_KPROBES */ 538 539 #ifndef CONFIG_OPTPROBES 540 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 541 { 542 return false; 543 } 544 #endif /* !CONFIG_OPTPROBES */ 545 546 #ifdef CONFIG_KRETPROBES 547 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 548 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 549 { 550 return is_rethook_trampoline(addr); 551 } 552 553 static nokprobe_inline 554 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 555 struct llist_node **cur) 556 { 557 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur); 558 } 559 #else 560 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 561 { 562 return (void *)addr == kretprobe_trampoline_addr(); 563 } 564 565 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 566 struct llist_node **cur); 567 #endif 568 #else 569 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 570 { 571 return false; 572 } 573 574 static nokprobe_inline 575 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 576 struct llist_node **cur) 577 { 578 return 0; 579 } 580 #endif 581 582 /* Returns true if kprobes handled the fault */ 583 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 584 unsigned int trap) 585 { 586 if (!IS_ENABLED(CONFIG_KPROBES)) 587 return false; 588 if (user_mode(regs)) 589 return false; 590 /* 591 * To be potentially processing a kprobe fault and to be allowed 592 * to call kprobe_running(), we have to be non-preemptible. 593 */ 594 if (preemptible()) 595 return false; 596 if (!kprobe_running()) 597 return false; 598 return kprobe_fault_handler(regs, trap); 599 } 600 601 #endif /* _LINUX_KPROBES_H */ 602