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 *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 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 206 "Kretprobe is accessed from instance under preemptive context"); 207 208 return (struct kretprobe *)READ_ONCE(ri->node.rethook->data); 209 } 210 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 211 { 212 return ri->node.ret_addr; 213 } 214 #else 215 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 216 struct pt_regs *regs); 217 void arch_kretprobe_fixup_return(struct pt_regs *regs, 218 kprobe_opcode_t *correct_ret_addr); 219 220 void __kretprobe_trampoline(void); 221 /* 222 * Since some architecture uses structured function pointer, 223 * use dereference_function_descriptor() to get real function address. 224 */ 225 static nokprobe_inline void *kretprobe_trampoline_addr(void) 226 { 227 return dereference_kernel_function_descriptor(__kretprobe_trampoline); 228 } 229 230 /* If the trampoline handler called from a kprobe, use this version */ 231 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 232 void *frame_pointer); 233 234 static nokprobe_inline 235 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 236 void *frame_pointer) 237 { 238 unsigned long ret; 239 /* 240 * Set a dummy kprobe for avoiding kretprobe recursion. 241 * Since kretprobe never runs in kprobe handler, no kprobe must 242 * be running at this point. 243 */ 244 kprobe_busy_begin(); 245 ret = __kretprobe_trampoline_handler(regs, frame_pointer); 246 kprobe_busy_end(); 247 248 return ret; 249 } 250 251 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 252 { 253 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 254 "Kretprobe is accessed from instance under preemptive context"); 255 256 return READ_ONCE(ri->rph->rp); 257 } 258 259 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 260 { 261 return (unsigned long)ri->ret_addr; 262 } 263 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */ 264 265 #else /* !CONFIG_KRETPROBES */ 266 static inline void arch_prepare_kretprobe(struct kretprobe *rp, 267 struct pt_regs *regs) 268 { 269 } 270 static inline int arch_trampoline_kprobe(struct kprobe *p) 271 { 272 return 0; 273 } 274 #endif /* CONFIG_KRETPROBES */ 275 276 /* Markers of '_kprobe_blacklist' section */ 277 extern unsigned long __start_kprobe_blacklist[]; 278 extern unsigned long __stop_kprobe_blacklist[]; 279 280 extern struct kretprobe_blackpoint kretprobe_blacklist[]; 281 282 #ifdef CONFIG_KPROBES_SANITY_TEST 283 extern int init_test_probes(void); 284 #else /* !CONFIG_KPROBES_SANITY_TEST */ 285 static inline int init_test_probes(void) 286 { 287 return 0; 288 } 289 #endif /* CONFIG_KPROBES_SANITY_TEST */ 290 291 extern int arch_prepare_kprobe(struct kprobe *p); 292 extern void arch_arm_kprobe(struct kprobe *p); 293 extern void arch_disarm_kprobe(struct kprobe *p); 294 extern int arch_init_kprobes(void); 295 extern void kprobes_inc_nmissed_count(struct kprobe *p); 296 extern bool arch_within_kprobe_blacklist(unsigned long addr); 297 extern int arch_populate_kprobe_blacklist(void); 298 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); 299 300 extern bool within_kprobe_blacklist(unsigned long addr); 301 extern int kprobe_add_ksym_blacklist(unsigned long entry); 302 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end); 303 304 struct kprobe_insn_cache { 305 struct mutex mutex; 306 void *(*alloc)(void); /* allocate insn page */ 307 void (*free)(void *); /* free insn page */ 308 const char *sym; /* symbol for insn pages */ 309 struct list_head pages; /* list of kprobe_insn_page */ 310 size_t insn_size; /* size of instruction slot */ 311 int nr_garbage; 312 }; 313 314 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 315 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c); 316 extern void __free_insn_slot(struct kprobe_insn_cache *c, 317 kprobe_opcode_t *slot, int dirty); 318 /* sleep-less address checking routine */ 319 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c, 320 unsigned long addr); 321 322 #define DEFINE_INSN_CACHE_OPS(__name) \ 323 extern struct kprobe_insn_cache kprobe_##__name##_slots; \ 324 \ 325 static inline kprobe_opcode_t *get_##__name##_slot(void) \ 326 { \ 327 return __get_insn_slot(&kprobe_##__name##_slots); \ 328 } \ 329 \ 330 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\ 331 { \ 332 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \ 333 } \ 334 \ 335 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 336 { \ 337 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \ 338 } 339 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page" 340 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page" 341 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, 342 unsigned long *value, char *type, char *sym); 343 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */ 344 #define DEFINE_INSN_CACHE_OPS(__name) \ 345 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 346 { \ 347 return 0; \ 348 } 349 #endif 350 351 DEFINE_INSN_CACHE_OPS(insn); 352 353 #ifdef CONFIG_OPTPROBES 354 /* 355 * Internal structure for direct jump optimized probe 356 */ 357 struct optimized_kprobe { 358 struct kprobe kp; 359 struct list_head list; /* list for optimizing queue */ 360 struct arch_optimized_insn optinsn; 361 }; 362 363 /* Architecture dependent functions for direct jump optimization */ 364 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); 365 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); 366 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, 367 struct kprobe *orig); 368 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); 369 extern void arch_optimize_kprobes(struct list_head *oplist); 370 extern void arch_unoptimize_kprobes(struct list_head *oplist, 371 struct list_head *done_list); 372 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); 373 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op, 374 kprobe_opcode_t *addr); 375 376 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 377 378 DEFINE_INSN_CACHE_OPS(optinsn); 379 380 extern void wait_for_kprobe_optimizer(void); 381 bool optprobe_queued_unopt(struct optimized_kprobe *op); 382 bool kprobe_disarmed(struct kprobe *p); 383 #else /* !CONFIG_OPTPROBES */ 384 static inline void wait_for_kprobe_optimizer(void) { } 385 #endif /* CONFIG_OPTPROBES */ 386 387 #ifdef CONFIG_KPROBES_ON_FTRACE 388 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 389 struct ftrace_ops *ops, struct ftrace_regs *fregs); 390 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 391 #else 392 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p) 393 { 394 return -EINVAL; 395 } 396 #endif /* CONFIG_KPROBES_ON_FTRACE */ 397 398 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 399 struct kprobe *get_kprobe(void *addr); 400 401 /* kprobe_running() will just return the current_kprobe on this CPU */ 402 static inline struct kprobe *kprobe_running(void) 403 { 404 return __this_cpu_read(current_kprobe); 405 } 406 407 static inline void reset_current_kprobe(void) 408 { 409 __this_cpu_write(current_kprobe, NULL); 410 } 411 412 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 413 { 414 return this_cpu_ptr(&kprobe_ctlblk); 415 } 416 417 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 418 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry); 419 420 int register_kprobe(struct kprobe *p); 421 void unregister_kprobe(struct kprobe *p); 422 int register_kprobes(struct kprobe **kps, int num); 423 void unregister_kprobes(struct kprobe **kps, int num); 424 425 int register_kretprobe(struct kretprobe *rp); 426 void unregister_kretprobe(struct kretprobe *rp); 427 int register_kretprobes(struct kretprobe **rps, int num); 428 void unregister_kretprobes(struct kretprobe **rps, int num); 429 430 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES) 431 #define kprobe_flush_task(tk) do {} while (0) 432 #else 433 void kprobe_flush_task(struct task_struct *tk); 434 #endif 435 436 void kprobe_free_init_mem(void); 437 438 int disable_kprobe(struct kprobe *kp); 439 int enable_kprobe(struct kprobe *kp); 440 441 void dump_kprobe(struct kprobe *kp); 442 443 void *alloc_insn_page(void); 444 445 void *alloc_optinsn_page(void); 446 void free_optinsn_page(void *page); 447 448 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 449 char *sym); 450 451 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 452 char *type, char *sym); 453 #else /* !CONFIG_KPROBES: */ 454 455 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 456 { 457 return 0; 458 } 459 static inline struct kprobe *get_kprobe(void *addr) 460 { 461 return NULL; 462 } 463 static inline struct kprobe *kprobe_running(void) 464 { 465 return NULL; 466 } 467 #define kprobe_busy_begin() do {} while (0) 468 #define kprobe_busy_end() do {} while (0) 469 470 static inline int register_kprobe(struct kprobe *p) 471 { 472 return -EOPNOTSUPP; 473 } 474 static inline int register_kprobes(struct kprobe **kps, int num) 475 { 476 return -EOPNOTSUPP; 477 } 478 static inline void unregister_kprobe(struct kprobe *p) 479 { 480 } 481 static inline void unregister_kprobes(struct kprobe **kps, int num) 482 { 483 } 484 static inline int register_kretprobe(struct kretprobe *rp) 485 { 486 return -EOPNOTSUPP; 487 } 488 static inline int register_kretprobes(struct kretprobe **rps, int num) 489 { 490 return -EOPNOTSUPP; 491 } 492 static inline void unregister_kretprobe(struct kretprobe *rp) 493 { 494 } 495 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 496 { 497 } 498 static inline void kprobe_flush_task(struct task_struct *tk) 499 { 500 } 501 static inline void kprobe_free_init_mem(void) 502 { 503 } 504 static inline int disable_kprobe(struct kprobe *kp) 505 { 506 return -EOPNOTSUPP; 507 } 508 static inline int enable_kprobe(struct kprobe *kp) 509 { 510 return -EOPNOTSUPP; 511 } 512 513 static inline bool within_kprobe_blacklist(unsigned long addr) 514 { 515 return true; 516 } 517 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 518 char *type, char *sym) 519 { 520 return -ERANGE; 521 } 522 #endif /* CONFIG_KPROBES */ 523 524 static inline int disable_kretprobe(struct kretprobe *rp) 525 { 526 return disable_kprobe(&rp->kp); 527 } 528 static inline int enable_kretprobe(struct kretprobe *rp) 529 { 530 return enable_kprobe(&rp->kp); 531 } 532 533 #ifndef CONFIG_KPROBES 534 static inline bool is_kprobe_insn_slot(unsigned long addr) 535 { 536 return false; 537 } 538 #endif /* !CONFIG_KPROBES */ 539 540 #ifndef CONFIG_OPTPROBES 541 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 542 { 543 return false; 544 } 545 #endif /* !CONFIG_OPTPROBES */ 546 547 #ifdef CONFIG_KRETPROBES 548 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 549 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 550 { 551 return is_rethook_trampoline(addr); 552 } 553 554 static nokprobe_inline 555 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 556 struct llist_node **cur) 557 { 558 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur); 559 } 560 #else 561 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 562 { 563 return (void *)addr == kretprobe_trampoline_addr(); 564 } 565 566 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 567 struct llist_node **cur); 568 #endif 569 #else 570 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 571 { 572 return false; 573 } 574 575 static nokprobe_inline 576 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 577 struct llist_node **cur) 578 { 579 return 0; 580 } 581 #endif 582 583 /* Returns true if kprobes handled the fault */ 584 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 585 unsigned int trap) 586 { 587 if (!IS_ENABLED(CONFIG_KPROBES)) 588 return false; 589 if (user_mode(regs)) 590 return false; 591 /* 592 * To be potentially processing a kprobe fault and to be allowed 593 * to call kprobe_running(), we have to be non-preemptible. 594 */ 595 if (preemptible()) 596 return false; 597 if (!kprobe_running()) 598 return false; 599 return kprobe_fault_handler(regs, trap); 600 } 601 602 #endif /* _LINUX_KPROBES_H */ 603