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/refcount.h> 30 #include <linux/freelist.h> 31 #include <linux/rethook.h> 32 #include <asm/kprobes.h> 33 34 #ifdef CONFIG_KPROBES 35 36 /* kprobe_status settings */ 37 #define KPROBE_HIT_ACTIVE 0x00000001 38 #define KPROBE_HIT_SS 0x00000002 39 #define KPROBE_REENTER 0x00000004 40 #define KPROBE_HIT_SSDONE 0x00000008 41 42 #else /* !CONFIG_KPROBES */ 43 #include <asm-generic/kprobes.h> 44 typedef int kprobe_opcode_t; 45 struct arch_specific_insn { 46 int dummy; 47 }; 48 #endif /* CONFIG_KPROBES */ 49 50 struct kprobe; 51 struct pt_regs; 52 struct kretprobe; 53 struct kretprobe_instance; 54 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *); 55 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *, 56 unsigned long flags); 57 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *, 58 struct pt_regs *); 59 60 struct kprobe { 61 struct hlist_node hlist; 62 63 /* list of kprobes for multi-handler support */ 64 struct list_head list; 65 66 /*count the number of times this probe was temporarily disarmed */ 67 unsigned long nmissed; 68 69 /* location of the probe point */ 70 kprobe_opcode_t *addr; 71 72 /* Allow user to indicate symbol name of the probe point */ 73 const char *symbol_name; 74 75 /* Offset into the symbol */ 76 unsigned int offset; 77 78 /* Called before addr is executed. */ 79 kprobe_pre_handler_t pre_handler; 80 81 /* Called after addr is executed, unless... */ 82 kprobe_post_handler_t post_handler; 83 84 /* Saved opcode (which has been replaced with breakpoint) */ 85 kprobe_opcode_t opcode; 86 87 /* copy of the original instruction */ 88 struct arch_specific_insn ainsn; 89 90 /* 91 * Indicates various status flags. 92 * Protected by kprobe_mutex after this kprobe is registered. 93 */ 94 u32 flags; 95 }; 96 97 /* Kprobe status flags */ 98 #define KPROBE_FLAG_GONE 1 /* breakpoint has already gone */ 99 #define KPROBE_FLAG_DISABLED 2 /* probe is temporarily disabled */ 100 #define KPROBE_FLAG_OPTIMIZED 4 /* 101 * probe is really optimized. 102 * NOTE: 103 * this flag is only for optimized_kprobe. 104 */ 105 #define KPROBE_FLAG_FTRACE 8 /* probe is using ftrace */ 106 #define KPROBE_FLAG_ON_FUNC_ENTRY 16 /* probe is on the function entry */ 107 108 /* Has this kprobe gone ? */ 109 static inline bool kprobe_gone(struct kprobe *p) 110 { 111 return p->flags & KPROBE_FLAG_GONE; 112 } 113 114 /* Is this kprobe disabled ? */ 115 static inline bool kprobe_disabled(struct kprobe *p) 116 { 117 return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE); 118 } 119 120 /* Is this kprobe really running optimized path ? */ 121 static inline bool kprobe_optimized(struct kprobe *p) 122 { 123 return p->flags & KPROBE_FLAG_OPTIMIZED; 124 } 125 126 /* Is this kprobe uses ftrace ? */ 127 static inline bool kprobe_ftrace(struct kprobe *p) 128 { 129 return p->flags & KPROBE_FLAG_FTRACE; 130 } 131 132 /* 133 * Function-return probe - 134 * Note: 135 * User needs to provide a handler function, and initialize maxactive. 136 * maxactive - The maximum number of instances of the probed function that 137 * can be active concurrently. 138 * nmissed - tracks the number of times the probed function's return was 139 * ignored, due to maxactive being too low. 140 * 141 */ 142 struct kretprobe_holder { 143 struct kretprobe __rcu *rp; 144 refcount_t ref; 145 }; 146 147 struct kretprobe { 148 struct kprobe kp; 149 kretprobe_handler_t handler; 150 kretprobe_handler_t entry_handler; 151 int maxactive; 152 int nmissed; 153 size_t data_size; 154 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 155 struct rethook *rh; 156 #else 157 struct freelist_head freelist; 158 struct kretprobe_holder *rph; 159 #endif 160 }; 161 162 #define KRETPROBE_MAX_DATA_SIZE 4096 163 164 struct kretprobe_instance { 165 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 166 struct rethook_node node; 167 #else 168 union { 169 struct freelist_node freelist; 170 struct rcu_head rcu; 171 }; 172 struct llist_node llist; 173 struct kretprobe_holder *rph; 174 kprobe_opcode_t *ret_addr; 175 void *fp; 176 #endif 177 char data[]; 178 }; 179 180 struct kretprobe_blackpoint { 181 const char *name; 182 void *addr; 183 }; 184 185 struct kprobe_blacklist_entry { 186 struct list_head list; 187 unsigned long start_addr; 188 unsigned long end_addr; 189 }; 190 191 #ifdef CONFIG_KPROBES 192 DECLARE_PER_CPU(struct kprobe *, current_kprobe); 193 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 194 195 extern void kprobe_busy_begin(void); 196 extern void kprobe_busy_end(void); 197 198 #ifdef CONFIG_KRETPROBES 199 /* Check whether @p is used for implementing a trampoline. */ 200 extern int arch_trampoline_kprobe(struct kprobe *p); 201 202 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 203 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 204 { 205 /* rethook::data is non-changed field, so that you can access it freely. */ 206 return (struct kretprobe *)ri->node.rethook->data; 207 } 208 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 209 { 210 return ri->node.ret_addr; 211 } 212 #else 213 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 214 struct pt_regs *regs); 215 void arch_kretprobe_fixup_return(struct pt_regs *regs, 216 kprobe_opcode_t *correct_ret_addr); 217 218 void __kretprobe_trampoline(void); 219 /* 220 * Since some architecture uses structured function pointer, 221 * use dereference_function_descriptor() to get real function address. 222 */ 223 static nokprobe_inline void *kretprobe_trampoline_addr(void) 224 { 225 return dereference_kernel_function_descriptor(__kretprobe_trampoline); 226 } 227 228 /* If the trampoline handler called from a kprobe, use this version */ 229 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 230 void *frame_pointer); 231 232 static nokprobe_inline 233 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 234 void *frame_pointer) 235 { 236 unsigned long ret; 237 /* 238 * Set a dummy kprobe for avoiding kretprobe recursion. 239 * Since kretprobe never runs in kprobe handler, no kprobe must 240 * be running at this point. 241 */ 242 kprobe_busy_begin(); 243 ret = __kretprobe_trampoline_handler(regs, frame_pointer); 244 kprobe_busy_end(); 245 246 return ret; 247 } 248 249 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 250 { 251 return rcu_dereference_check(ri->rph->rp, rcu_read_lock_any_held()); 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 #else /* !CONFIG_KPROBES: */ 449 450 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 451 { 452 return 0; 453 } 454 static inline struct kprobe *get_kprobe(void *addr) 455 { 456 return NULL; 457 } 458 static inline struct kprobe *kprobe_running(void) 459 { 460 return NULL; 461 } 462 #define kprobe_busy_begin() do {} while (0) 463 #define kprobe_busy_end() do {} while (0) 464 465 static inline int register_kprobe(struct kprobe *p) 466 { 467 return -EOPNOTSUPP; 468 } 469 static inline int register_kprobes(struct kprobe **kps, int num) 470 { 471 return -EOPNOTSUPP; 472 } 473 static inline void unregister_kprobe(struct kprobe *p) 474 { 475 } 476 static inline void unregister_kprobes(struct kprobe **kps, int num) 477 { 478 } 479 static inline int register_kretprobe(struct kretprobe *rp) 480 { 481 return -EOPNOTSUPP; 482 } 483 static inline int register_kretprobes(struct kretprobe **rps, int num) 484 { 485 return -EOPNOTSUPP; 486 } 487 static inline void unregister_kretprobe(struct kretprobe *rp) 488 { 489 } 490 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 491 { 492 } 493 static inline void kprobe_flush_task(struct task_struct *tk) 494 { 495 } 496 static inline void kprobe_free_init_mem(void) 497 { 498 } 499 static inline int disable_kprobe(struct kprobe *kp) 500 { 501 return -EOPNOTSUPP; 502 } 503 static inline int enable_kprobe(struct kprobe *kp) 504 { 505 return -EOPNOTSUPP; 506 } 507 508 static inline bool within_kprobe_blacklist(unsigned long addr) 509 { 510 return true; 511 } 512 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 513 char *type, char *sym) 514 { 515 return -ERANGE; 516 } 517 #endif /* CONFIG_KPROBES */ 518 519 static inline int disable_kretprobe(struct kretprobe *rp) 520 { 521 return disable_kprobe(&rp->kp); 522 } 523 static inline int enable_kretprobe(struct kretprobe *rp) 524 { 525 return enable_kprobe(&rp->kp); 526 } 527 528 #ifndef CONFIG_KPROBES 529 static inline bool is_kprobe_insn_slot(unsigned long addr) 530 { 531 return false; 532 } 533 #endif /* !CONFIG_KPROBES */ 534 535 #ifndef CONFIG_OPTPROBES 536 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 537 { 538 return false; 539 } 540 #endif /* !CONFIG_OPTPROBES */ 541 542 #ifdef CONFIG_KRETPROBES 543 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 544 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 545 { 546 return is_rethook_trampoline(addr); 547 } 548 549 static nokprobe_inline 550 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 551 struct llist_node **cur) 552 { 553 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur); 554 } 555 #else 556 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 557 { 558 return (void *)addr == kretprobe_trampoline_addr(); 559 } 560 561 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 562 struct llist_node **cur); 563 #endif 564 #else 565 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 566 { 567 return false; 568 } 569 570 static nokprobe_inline 571 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 572 struct llist_node **cur) 573 { 574 return 0; 575 } 576 #endif 577 578 /* Returns true if kprobes handled the fault */ 579 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 580 unsigned int trap) 581 { 582 if (!IS_ENABLED(CONFIG_KPROBES)) 583 return false; 584 if (user_mode(regs)) 585 return false; 586 /* 587 * To be potentially processing a kprobe fault and to be allowed 588 * to call kprobe_running(), we have to be non-preemptible. 589 */ 590 if (preemptible()) 591 return false; 592 if (!kprobe_running()) 593 return false; 594 return kprobe_fault_handler(regs, trap); 595 } 596 597 #endif /* _LINUX_KPROBES_H */ 598