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 <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 */ 105 106 /* Has this kprobe gone ? */ 107 static inline bool kprobe_gone(struct kprobe *p) 108 { 109 return p->flags & KPROBE_FLAG_GONE; 110 } 111 112 /* Is this kprobe disabled ? */ 113 static inline bool kprobe_disabled(struct kprobe *p) 114 { 115 return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE); 116 } 117 118 /* Is this kprobe really running optimized path ? */ 119 static inline bool kprobe_optimized(struct kprobe *p) 120 { 121 return p->flags & KPROBE_FLAG_OPTIMIZED; 122 } 123 124 /* Is this kprobe uses ftrace ? */ 125 static inline bool kprobe_ftrace(struct kprobe *p) 126 { 127 return p->flags & KPROBE_FLAG_FTRACE; 128 } 129 130 /* 131 * Function-return probe - 132 * Note: 133 * User needs to provide a handler function, and initialize maxactive. 134 * maxactive - The maximum number of instances of the probed function that 135 * can be active concurrently. 136 * nmissed - tracks the number of times the probed function's return was 137 * ignored, due to maxactive being too low. 138 * 139 */ 140 struct kretprobe_holder { 141 struct kretprobe *rp; 142 refcount_t ref; 143 }; 144 145 struct kretprobe { 146 struct kprobe kp; 147 kretprobe_handler_t handler; 148 kretprobe_handler_t entry_handler; 149 int maxactive; 150 int nmissed; 151 size_t data_size; 152 struct freelist_head freelist; 153 struct kretprobe_holder *rph; 154 }; 155 156 #define KRETPROBE_MAX_DATA_SIZE 4096 157 158 struct kretprobe_instance { 159 union { 160 struct freelist_node freelist; 161 struct rcu_head rcu; 162 }; 163 struct llist_node llist; 164 struct kretprobe_holder *rph; 165 kprobe_opcode_t *ret_addr; 166 void *fp; 167 char data[]; 168 }; 169 170 struct kretprobe_blackpoint { 171 const char *name; 172 void *addr; 173 }; 174 175 struct kprobe_blacklist_entry { 176 struct list_head list; 177 unsigned long start_addr; 178 unsigned long end_addr; 179 }; 180 181 #ifdef CONFIG_KPROBES 182 DECLARE_PER_CPU(struct kprobe *, current_kprobe); 183 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 184 185 extern void kprobe_busy_begin(void); 186 extern void kprobe_busy_end(void); 187 188 #ifdef CONFIG_KRETPROBES 189 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 190 struct pt_regs *regs); 191 extern int arch_trampoline_kprobe(struct kprobe *p); 192 193 void arch_kretprobe_fixup_return(struct pt_regs *regs, 194 kprobe_opcode_t *correct_ret_addr); 195 196 void __kretprobe_trampoline(void); 197 /* 198 * Since some architecture uses structured function pointer, 199 * use dereference_function_descriptor() to get real function address. 200 */ 201 static nokprobe_inline void *kretprobe_trampoline_addr(void) 202 { 203 return dereference_kernel_function_descriptor(__kretprobe_trampoline); 204 } 205 206 /* If the trampoline handler called from a kprobe, use this version */ 207 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 208 void *frame_pointer); 209 210 static nokprobe_inline 211 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 212 void *frame_pointer) 213 { 214 unsigned long ret; 215 /* 216 * Set a dummy kprobe for avoiding kretprobe recursion. 217 * Since kretprobe never runs in kprobe handler, no kprobe must 218 * be running at this point. 219 */ 220 kprobe_busy_begin(); 221 ret = __kretprobe_trampoline_handler(regs, frame_pointer); 222 kprobe_busy_end(); 223 224 return ret; 225 } 226 227 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 228 { 229 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 230 "Kretprobe is accessed from instance under preemptive context"); 231 232 return READ_ONCE(ri->rph->rp); 233 } 234 235 #else /* !CONFIG_KRETPROBES */ 236 static inline void arch_prepare_kretprobe(struct kretprobe *rp, 237 struct pt_regs *regs) 238 { 239 } 240 static inline int arch_trampoline_kprobe(struct kprobe *p) 241 { 242 return 0; 243 } 244 #endif /* CONFIG_KRETPROBES */ 245 246 /* Markers of '_kprobe_blacklist' section */ 247 extern unsigned long __start_kprobe_blacklist[]; 248 extern unsigned long __stop_kprobe_blacklist[]; 249 250 extern struct kretprobe_blackpoint kretprobe_blacklist[]; 251 252 #ifdef CONFIG_KPROBES_SANITY_TEST 253 extern int init_test_probes(void); 254 #else /* !CONFIG_KPROBES_SANITY_TEST */ 255 static inline int init_test_probes(void) 256 { 257 return 0; 258 } 259 #endif /* CONFIG_KPROBES_SANITY_TEST */ 260 261 extern int arch_prepare_kprobe(struct kprobe *p); 262 extern void arch_arm_kprobe(struct kprobe *p); 263 extern void arch_disarm_kprobe(struct kprobe *p); 264 extern int arch_init_kprobes(void); 265 extern void kprobes_inc_nmissed_count(struct kprobe *p); 266 extern bool arch_within_kprobe_blacklist(unsigned long addr); 267 extern int arch_populate_kprobe_blacklist(void); 268 extern bool arch_kprobe_on_func_entry(unsigned long offset); 269 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); 270 271 extern bool within_kprobe_blacklist(unsigned long addr); 272 extern int kprobe_add_ksym_blacklist(unsigned long entry); 273 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end); 274 275 struct kprobe_insn_cache { 276 struct mutex mutex; 277 void *(*alloc)(void); /* allocate insn page */ 278 void (*free)(void *); /* free insn page */ 279 const char *sym; /* symbol for insn pages */ 280 struct list_head pages; /* list of kprobe_insn_page */ 281 size_t insn_size; /* size of instruction slot */ 282 int nr_garbage; 283 }; 284 285 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 286 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c); 287 extern void __free_insn_slot(struct kprobe_insn_cache *c, 288 kprobe_opcode_t *slot, int dirty); 289 /* sleep-less address checking routine */ 290 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c, 291 unsigned long addr); 292 293 #define DEFINE_INSN_CACHE_OPS(__name) \ 294 extern struct kprobe_insn_cache kprobe_##__name##_slots; \ 295 \ 296 static inline kprobe_opcode_t *get_##__name##_slot(void) \ 297 { \ 298 return __get_insn_slot(&kprobe_##__name##_slots); \ 299 } \ 300 \ 301 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\ 302 { \ 303 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \ 304 } \ 305 \ 306 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 307 { \ 308 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \ 309 } 310 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page" 311 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page" 312 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, 313 unsigned long *value, char *type, char *sym); 314 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */ 315 #define DEFINE_INSN_CACHE_OPS(__name) \ 316 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 317 { \ 318 return 0; \ 319 } 320 #endif 321 322 DEFINE_INSN_CACHE_OPS(insn); 323 324 #ifdef CONFIG_OPTPROBES 325 /* 326 * Internal structure for direct jump optimized probe 327 */ 328 struct optimized_kprobe { 329 struct kprobe kp; 330 struct list_head list; /* list for optimizing queue */ 331 struct arch_optimized_insn optinsn; 332 }; 333 334 /* Architecture dependent functions for direct jump optimization */ 335 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); 336 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); 337 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, 338 struct kprobe *orig); 339 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); 340 extern void arch_optimize_kprobes(struct list_head *oplist); 341 extern void arch_unoptimize_kprobes(struct list_head *oplist, 342 struct list_head *done_list); 343 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); 344 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op, 345 kprobe_opcode_t *addr); 346 347 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 348 349 DEFINE_INSN_CACHE_OPS(optinsn); 350 351 extern void wait_for_kprobe_optimizer(void); 352 #else /* !CONFIG_OPTPROBES */ 353 static inline void wait_for_kprobe_optimizer(void) { } 354 #endif /* CONFIG_OPTPROBES */ 355 356 #ifdef CONFIG_KPROBES_ON_FTRACE 357 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 358 struct ftrace_ops *ops, struct ftrace_regs *fregs); 359 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 360 #else 361 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p) 362 { 363 return -EINVAL; 364 } 365 #endif /* CONFIG_KPROBES_ON_FTRACE */ 366 367 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 368 struct kprobe *get_kprobe(void *addr); 369 370 /* kprobe_running() will just return the current_kprobe on this CPU */ 371 static inline struct kprobe *kprobe_running(void) 372 { 373 return __this_cpu_read(current_kprobe); 374 } 375 376 static inline void reset_current_kprobe(void) 377 { 378 __this_cpu_write(current_kprobe, NULL); 379 } 380 381 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 382 { 383 return this_cpu_ptr(&kprobe_ctlblk); 384 } 385 386 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 387 int register_kprobe(struct kprobe *p); 388 void unregister_kprobe(struct kprobe *p); 389 int register_kprobes(struct kprobe **kps, int num); 390 void unregister_kprobes(struct kprobe **kps, int num); 391 392 int register_kretprobe(struct kretprobe *rp); 393 void unregister_kretprobe(struct kretprobe *rp); 394 int register_kretprobes(struct kretprobe **rps, int num); 395 void unregister_kretprobes(struct kretprobe **rps, int num); 396 397 void kprobe_flush_task(struct task_struct *tk); 398 399 void kprobe_free_init_mem(void); 400 401 int disable_kprobe(struct kprobe *kp); 402 int enable_kprobe(struct kprobe *kp); 403 404 void dump_kprobe(struct kprobe *kp); 405 406 void *alloc_insn_page(void); 407 408 void *alloc_optinsn_page(void); 409 void free_optinsn_page(void *page); 410 411 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 412 char *sym); 413 414 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 415 char *type, char *sym); 416 #else /* !CONFIG_KPROBES: */ 417 418 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 419 { 420 return 0; 421 } 422 static inline struct kprobe *get_kprobe(void *addr) 423 { 424 return NULL; 425 } 426 static inline struct kprobe *kprobe_running(void) 427 { 428 return NULL; 429 } 430 static inline int register_kprobe(struct kprobe *p) 431 { 432 return -EOPNOTSUPP; 433 } 434 static inline int register_kprobes(struct kprobe **kps, int num) 435 { 436 return -EOPNOTSUPP; 437 } 438 static inline void unregister_kprobe(struct kprobe *p) 439 { 440 } 441 static inline void unregister_kprobes(struct kprobe **kps, int num) 442 { 443 } 444 static inline int register_kretprobe(struct kretprobe *rp) 445 { 446 return -EOPNOTSUPP; 447 } 448 static inline int register_kretprobes(struct kretprobe **rps, int num) 449 { 450 return -EOPNOTSUPP; 451 } 452 static inline void unregister_kretprobe(struct kretprobe *rp) 453 { 454 } 455 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 456 { 457 } 458 static inline void kprobe_flush_task(struct task_struct *tk) 459 { 460 } 461 static inline void kprobe_free_init_mem(void) 462 { 463 } 464 static inline int disable_kprobe(struct kprobe *kp) 465 { 466 return -EOPNOTSUPP; 467 } 468 static inline int enable_kprobe(struct kprobe *kp) 469 { 470 return -EOPNOTSUPP; 471 } 472 473 static inline bool within_kprobe_blacklist(unsigned long addr) 474 { 475 return true; 476 } 477 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 478 char *type, char *sym) 479 { 480 return -ERANGE; 481 } 482 #endif /* CONFIG_KPROBES */ 483 484 static inline int disable_kretprobe(struct kretprobe *rp) 485 { 486 return disable_kprobe(&rp->kp); 487 } 488 static inline int enable_kretprobe(struct kretprobe *rp) 489 { 490 return enable_kprobe(&rp->kp); 491 } 492 493 #ifndef CONFIG_KPROBES 494 static inline bool is_kprobe_insn_slot(unsigned long addr) 495 { 496 return false; 497 } 498 #endif /* !CONFIG_KPROBES */ 499 500 #ifndef CONFIG_OPTPROBES 501 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 502 { 503 return false; 504 } 505 #endif /* !CONFIG_OPTPROBES */ 506 507 #ifdef CONFIG_KRETPROBES 508 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 509 { 510 return (void *)addr == kretprobe_trampoline_addr(); 511 } 512 513 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 514 struct llist_node **cur); 515 #else 516 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) 517 { 518 return false; 519 } 520 521 static nokprobe_inline 522 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, 523 struct llist_node **cur) 524 { 525 return 0; 526 } 527 #endif 528 529 /* Returns true if kprobes handled the fault */ 530 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 531 unsigned int trap) 532 { 533 if (!IS_ENABLED(CONFIG_KPROBES)) 534 return false; 535 if (user_mode(regs)) 536 return false; 537 /* 538 * To be potentially processing a kprobe fault and to be allowed 539 * to call kprobe_running(), we have to be non-preemptible. 540 */ 541 if (preemptible()) 542 return false; 543 if (!kprobe_running()) 544 return false; 545 return kprobe_fault_handler(regs, trap); 546 } 547 548 #endif /* _LINUX_KPROBES_H */ 549