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 */ 106 107 /* 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 refcount_t ref; 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 freelist_head freelist; 157 struct kretprobe_holder *rph; 158 #endif 159 }; 160 161 #define KRETPROBE_MAX_DATA_SIZE 4096 162 163 struct kretprobe_instance { 164 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 165 struct rethook_node node; 166 #else 167 union { 168 struct freelist_node freelist; 169 struct rcu_head rcu; 170 }; 171 struct llist_node llist; 172 struct kretprobe_holder *rph; 173 kprobe_opcode_t *ret_addr; 174 void *fp; 175 #endif 176 char data[]; 177 }; 178 179 struct kretprobe_blackpoint { 180 const char *name; 181 void *addr; 182 }; 183 184 struct kprobe_blacklist_entry { 185 struct list_head list; 186 unsigned long start_addr; 187 unsigned long end_addr; 188 }; 189 190 #ifdef CONFIG_KPROBES 191 DECLARE_PER_CPU(struct kprobe *, current_kprobe); 192 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 193 194 extern void kprobe_busy_begin(void); 195 extern void kprobe_busy_end(void); 196 197 #ifdef CONFIG_KRETPROBES 198 /* Check whether @p is used for implementing a trampoline. */ 199 extern int arch_trampoline_kprobe(struct kprobe *p); 200 201 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 202 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 203 { 204 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 205 "Kretprobe is accessed from instance under preemptive context"); 206 207 return (struct kretprobe *)READ_ONCE(ri->node.rethook->data); 208 } 209 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 210 { 211 return ri->node.ret_addr; 212 } 213 #else 214 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 215 struct pt_regs *regs); 216 void arch_kretprobe_fixup_return(struct pt_regs *regs, 217 kprobe_opcode_t *correct_ret_addr); 218 219 void __kretprobe_trampoline(void); 220 /* 221 * Since some architecture uses structured function pointer, 222 * use dereference_function_descriptor() to get real function address. 223 */ 224 static nokprobe_inline void *kretprobe_trampoline_addr(void) 225 { 226 return dereference_kernel_function_descriptor(__kretprobe_trampoline); 227 } 228 229 /* If the trampoline handler called from a kprobe, use this version */ 230 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 231 void *frame_pointer); 232 233 static nokprobe_inline 234 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 235 void *frame_pointer) 236 { 237 unsigned long ret; 238 /* 239 * Set a dummy kprobe for avoiding kretprobe recursion. 240 * Since kretprobe never runs in kprobe handler, no kprobe must 241 * be running at this point. 242 */ 243 kprobe_busy_begin(); 244 ret = __kretprobe_trampoline_handler(regs, frame_pointer); 245 kprobe_busy_end(); 246 247 return ret; 248 } 249 250 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 251 { 252 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 253 "Kretprobe is accessed from instance under preemptive context"); 254 255 return READ_ONCE(ri->rph->rp); 256 } 257 258 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri) 259 { 260 return (unsigned long)ri->ret_addr; 261 } 262 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */ 263 264 #else /* !CONFIG_KRETPROBES */ 265 static inline void arch_prepare_kretprobe(struct kretprobe *rp, 266 struct pt_regs *regs) 267 { 268 } 269 static inline int arch_trampoline_kprobe(struct kprobe *p) 270 { 271 return 0; 272 } 273 #endif /* CONFIG_KRETPROBES */ 274 275 /* Markers of '_kprobe_blacklist' section */ 276 extern unsigned long __start_kprobe_blacklist[]; 277 extern unsigned long __stop_kprobe_blacklist[]; 278 279 extern struct kretprobe_blackpoint kretprobe_blacklist[]; 280 281 #ifdef CONFIG_KPROBES_SANITY_TEST 282 extern int init_test_probes(void); 283 #else /* !CONFIG_KPROBES_SANITY_TEST */ 284 static inline int init_test_probes(void) 285 { 286 return 0; 287 } 288 #endif /* CONFIG_KPROBES_SANITY_TEST */ 289 290 extern int arch_prepare_kprobe(struct kprobe *p); 291 extern void arch_arm_kprobe(struct kprobe *p); 292 extern void arch_disarm_kprobe(struct kprobe *p); 293 extern int arch_init_kprobes(void); 294 extern void kprobes_inc_nmissed_count(struct kprobe *p); 295 extern bool arch_within_kprobe_blacklist(unsigned long addr); 296 extern int arch_populate_kprobe_blacklist(void); 297 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); 298 299 extern bool within_kprobe_blacklist(unsigned long addr); 300 extern int kprobe_add_ksym_blacklist(unsigned long entry); 301 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end); 302 303 struct kprobe_insn_cache { 304 struct mutex mutex; 305 void *(*alloc)(void); /* allocate insn page */ 306 void (*free)(void *); /* free insn page */ 307 const char *sym; /* symbol for insn pages */ 308 struct list_head pages; /* list of kprobe_insn_page */ 309 size_t insn_size; /* size of instruction slot */ 310 int nr_garbage; 311 }; 312 313 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 314 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c); 315 extern void __free_insn_slot(struct kprobe_insn_cache *c, 316 kprobe_opcode_t *slot, int dirty); 317 /* sleep-less address checking routine */ 318 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c, 319 unsigned long addr); 320 321 #define DEFINE_INSN_CACHE_OPS(__name) \ 322 extern struct kprobe_insn_cache kprobe_##__name##_slots; \ 323 \ 324 static inline kprobe_opcode_t *get_##__name##_slot(void) \ 325 { \ 326 return __get_insn_slot(&kprobe_##__name##_slots); \ 327 } \ 328 \ 329 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\ 330 { \ 331 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \ 332 } \ 333 \ 334 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 335 { \ 336 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \ 337 } 338 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page" 339 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page" 340 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, 341 unsigned long *value, char *type, char *sym); 342 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */ 343 #define DEFINE_INSN_CACHE_OPS(__name) \ 344 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 345 { \ 346 return 0; \ 347 } 348 #endif 349 350 DEFINE_INSN_CACHE_OPS(insn); 351 352 #ifdef CONFIG_OPTPROBES 353 /* 354 * Internal structure for direct jump optimized probe 355 */ 356 struct optimized_kprobe { 357 struct kprobe kp; 358 struct list_head list; /* list for optimizing queue */ 359 struct arch_optimized_insn optinsn; 360 }; 361 362 /* Architecture dependent functions for direct jump optimization */ 363 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); 364 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); 365 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, 366 struct kprobe *orig); 367 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); 368 extern void arch_optimize_kprobes(struct list_head *oplist); 369 extern void arch_unoptimize_kprobes(struct list_head *oplist, 370 struct list_head *done_list); 371 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); 372 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op, 373 kprobe_opcode_t *addr); 374 375 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 376 377 DEFINE_INSN_CACHE_OPS(optinsn); 378 379 extern void wait_for_kprobe_optimizer(void); 380 #else /* !CONFIG_OPTPROBES */ 381 static inline void wait_for_kprobe_optimizer(void) { } 382 #endif /* CONFIG_OPTPROBES */ 383 384 #ifdef CONFIG_KPROBES_ON_FTRACE 385 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 386 struct ftrace_ops *ops, struct ftrace_regs *fregs); 387 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 388 #else 389 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p) 390 { 391 return -EINVAL; 392 } 393 #endif /* CONFIG_KPROBES_ON_FTRACE */ 394 395 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 396 struct kprobe *get_kprobe(void *addr); 397 398 /* kprobe_running() will just return the current_kprobe on this CPU */ 399 static inline struct kprobe *kprobe_running(void) 400 { 401 return __this_cpu_read(current_kprobe); 402 } 403 404 static inline void reset_current_kprobe(void) 405 { 406 __this_cpu_write(current_kprobe, NULL); 407 } 408 409 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 410 { 411 return this_cpu_ptr(&kprobe_ctlblk); 412 } 413 414 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 415 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry); 416 417 int register_kprobe(struct kprobe *p); 418 void unregister_kprobe(struct kprobe *p); 419 int register_kprobes(struct kprobe **kps, int num); 420 void unregister_kprobes(struct kprobe **kps, int num); 421 422 int register_kretprobe(struct kretprobe *rp); 423 void unregister_kretprobe(struct kretprobe *rp); 424 int register_kretprobes(struct kretprobe **rps, int num); 425 void unregister_kretprobes(struct kretprobe **rps, int num); 426 427 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 428 #define kprobe_flush_task(tk) do {} while (0) 429 #else 430 void kprobe_flush_task(struct task_struct *tk); 431 #endif 432 433 void kprobe_free_init_mem(void); 434 435 int disable_kprobe(struct kprobe *kp); 436 int enable_kprobe(struct kprobe *kp); 437 438 void dump_kprobe(struct kprobe *kp); 439 440 void *alloc_insn_page(void); 441 442 void *alloc_optinsn_page(void); 443 void free_optinsn_page(void *page); 444 445 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 446 char *sym); 447 448 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 449 char *type, char *sym); 450 #else /* !CONFIG_KPROBES: */ 451 452 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 453 { 454 return 0; 455 } 456 static inline struct kprobe *get_kprobe(void *addr) 457 { 458 return NULL; 459 } 460 static inline struct kprobe *kprobe_running(void) 461 { 462 return NULL; 463 } 464 #define kprobe_busy_begin() do {} while (0) 465 #define kprobe_busy_end() do {} while (0) 466 467 static inline int register_kprobe(struct kprobe *p) 468 { 469 return -EOPNOTSUPP; 470 } 471 static inline int register_kprobes(struct kprobe **kps, int num) 472 { 473 return -EOPNOTSUPP; 474 } 475 static inline void unregister_kprobe(struct kprobe *p) 476 { 477 } 478 static inline void unregister_kprobes(struct kprobe **kps, int num) 479 { 480 } 481 static inline int register_kretprobe(struct kretprobe *rp) 482 { 483 return -EOPNOTSUPP; 484 } 485 static inline int register_kretprobes(struct kretprobe **rps, int num) 486 { 487 return -EOPNOTSUPP; 488 } 489 static inline void unregister_kretprobe(struct kretprobe *rp) 490 { 491 } 492 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 493 { 494 } 495 static inline void kprobe_flush_task(struct task_struct *tk) 496 { 497 } 498 static inline void kprobe_free_init_mem(void) 499 { 500 } 501 static inline int disable_kprobe(struct kprobe *kp) 502 { 503 return -EOPNOTSUPP; 504 } 505 static inline int enable_kprobe(struct kprobe *kp) 506 { 507 return -EOPNOTSUPP; 508 } 509 510 static inline bool within_kprobe_blacklist(unsigned long addr) 511 { 512 return true; 513 } 514 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 515 char *type, char *sym) 516 { 517 return -ERANGE; 518 } 519 #endif /* CONFIG_KPROBES */ 520 521 static inline int disable_kretprobe(struct kretprobe *rp) 522 { 523 return disable_kprobe(&rp->kp); 524 } 525 static inline int enable_kretprobe(struct kretprobe *rp) 526 { 527 return enable_kprobe(&rp->kp); 528 } 529 530 #ifndef CONFIG_KPROBES 531 static inline bool is_kprobe_insn_slot(unsigned long addr) 532 { 533 return false; 534 } 535 #endif /* !CONFIG_KPROBES */ 536 537 #ifndef CONFIG_OPTPROBES 538 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 539 { 540 return false; 541 } 542 #endif /* !CONFIG_OPTPROBES */ 543 544 #ifdef CONFIG_KRETPROBES 545 #ifdef CONFIG_KRETPROBE_ON_RETHOOK 546 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 547 { 548 return is_rethook_trampoline(addr); 549 } 550 551 static nokprobe_inline 552 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 553 struct llist_node **cur) 554 { 555 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur); 556 } 557 #else 558 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 559 { 560 return (void *)addr == kretprobe_trampoline_addr(); 561 } 562 563 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 564 struct llist_node **cur); 565 #endif 566 #else 567 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 568 { 569 return false; 570 } 571 572 static nokprobe_inline 573 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 574 struct llist_node **cur) 575 { 576 return 0; 577 } 578 #endif 579 580 /* Returns true if kprobes handled the fault */ 581 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 582 unsigned int trap) 583 { 584 if (!IS_ENABLED(CONFIG_KPROBES)) 585 return false; 586 if (user_mode(regs)) 587 return false; 588 /* 589 * To be potentially processing a kprobe fault and to be allowed 590 * to call kprobe_running(), we have to be non-preemptible. 591 */ 592 if (preemptible()) 593 return false; 594 if (!kprobe_running()) 595 return false; 596 return kprobe_fault_handler(regs, trap); 597 } 598 599 #endif /* _LINUX_KPROBES_H */ 600