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 * include/linux/kprobes.h 7 * 8 * Copyright (C) IBM Corporation, 2002, 2004 9 * 10 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel 11 * Probes initial implementation ( includes suggestions from 12 * Rusty Russell). 13 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes 14 * interface to access function arguments. 15 * 2005-May Hien Nguyen <hien@us.ibm.com> and Jim Keniston 16 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi 17 * <prasanna@in.ibm.com> added function-return probes. 18 */ 19 #include <linux/compiler.h> 20 #include <linux/linkage.h> 21 #include <linux/list.h> 22 #include <linux/notifier.h> 23 #include <linux/smp.h> 24 #include <linux/bug.h> 25 #include <linux/percpu.h> 26 #include <linux/spinlock.h> 27 #include <linux/rcupdate.h> 28 #include <linux/mutex.h> 29 #include <linux/ftrace.h> 30 #include <linux/refcount.h> 31 #include <linux/freelist.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 (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *, 58 int trapnr); 59 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *, 60 struct pt_regs *); 61 62 struct kprobe { 63 struct hlist_node hlist; 64 65 /* list of kprobes for multi-handler support */ 66 struct list_head list; 67 68 /*count the number of times this probe was temporarily disarmed */ 69 unsigned long nmissed; 70 71 /* location of the probe point */ 72 kprobe_opcode_t *addr; 73 74 /* Allow user to indicate symbol name of the probe point */ 75 const char *symbol_name; 76 77 /* Offset into the symbol */ 78 unsigned int offset; 79 80 /* Called before addr is executed. */ 81 kprobe_pre_handler_t pre_handler; 82 83 /* Called after addr is executed, unless... */ 84 kprobe_post_handler_t post_handler; 85 86 /* 87 * ... called if executing addr causes a fault (eg. page fault). 88 * Return 1 if it handled fault, otherwise kernel will see it. 89 */ 90 kprobe_fault_handler_t fault_handler; 91 92 /* Saved opcode (which has been replaced with breakpoint) */ 93 kprobe_opcode_t opcode; 94 95 /* copy of the original instruction */ 96 struct arch_specific_insn ainsn; 97 98 /* 99 * Indicates various status flags. 100 * Protected by kprobe_mutex after this kprobe is registered. 101 */ 102 u32 flags; 103 }; 104 105 /* Kprobe status flags */ 106 #define KPROBE_FLAG_GONE 1 /* breakpoint has already gone */ 107 #define KPROBE_FLAG_DISABLED 2 /* probe is temporarily disabled */ 108 #define KPROBE_FLAG_OPTIMIZED 4 /* 109 * probe is really optimized. 110 * NOTE: 111 * this flag is only for optimized_kprobe. 112 */ 113 #define KPROBE_FLAG_FTRACE 8 /* probe is using ftrace */ 114 115 /* Has this kprobe gone ? */ 116 static inline int kprobe_gone(struct kprobe *p) 117 { 118 return p->flags & KPROBE_FLAG_GONE; 119 } 120 121 /* Is this kprobe disabled ? */ 122 static inline int kprobe_disabled(struct kprobe *p) 123 { 124 return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE); 125 } 126 127 /* Is this kprobe really running optimized path ? */ 128 static inline int kprobe_optimized(struct kprobe *p) 129 { 130 return p->flags & KPROBE_FLAG_OPTIMIZED; 131 } 132 133 /* Is this kprobe uses ftrace ? */ 134 static inline int kprobe_ftrace(struct kprobe *p) 135 { 136 return p->flags & KPROBE_FLAG_FTRACE; 137 } 138 139 /* 140 * Function-return probe - 141 * Note: 142 * User needs to provide a handler function, and initialize maxactive. 143 * maxactive - The maximum number of instances of the probed function that 144 * can be active concurrently. 145 * nmissed - tracks the number of times the probed function's return was 146 * ignored, due to maxactive being too low. 147 * 148 */ 149 struct kretprobe_holder { 150 struct kretprobe *rp; 151 refcount_t ref; 152 }; 153 154 struct kretprobe { 155 struct kprobe kp; 156 kretprobe_handler_t handler; 157 kretprobe_handler_t entry_handler; 158 int maxactive; 159 int nmissed; 160 size_t data_size; 161 struct freelist_head freelist; 162 struct kretprobe_holder *rph; 163 }; 164 165 struct kretprobe_instance { 166 union { 167 struct freelist_node freelist; 168 struct rcu_head rcu; 169 }; 170 struct llist_node llist; 171 struct kretprobe_holder *rph; 172 kprobe_opcode_t *ret_addr; 173 void *fp; 174 char data[]; 175 }; 176 177 struct kretprobe_blackpoint { 178 const char *name; 179 void *addr; 180 }; 181 182 struct kprobe_blacklist_entry { 183 struct list_head list; 184 unsigned long start_addr; 185 unsigned long end_addr; 186 }; 187 188 #ifdef CONFIG_KPROBES 189 DECLARE_PER_CPU(struct kprobe *, current_kprobe); 190 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 191 192 /* 193 * For #ifdef avoidance: 194 */ 195 static inline int kprobes_built_in(void) 196 { 197 return 1; 198 } 199 200 extern void kprobe_busy_begin(void); 201 extern void kprobe_busy_end(void); 202 203 #ifdef CONFIG_KRETPROBES 204 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 205 struct pt_regs *regs); 206 extern int arch_trampoline_kprobe(struct kprobe *p); 207 208 /* If the trampoline handler called from a kprobe, use this version */ 209 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 210 void *trampoline_address, 211 void *frame_pointer); 212 213 static nokprobe_inline 214 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 215 void *trampoline_address, 216 void *frame_pointer) 217 { 218 unsigned long ret; 219 /* 220 * Set a dummy kprobe for avoiding kretprobe recursion. 221 * Since kretprobe never runs in kprobe handler, no kprobe must 222 * be running at this point. 223 */ 224 kprobe_busy_begin(); 225 ret = __kretprobe_trampoline_handler(regs, trampoline_address, frame_pointer); 226 kprobe_busy_end(); 227 228 return ret; 229 } 230 231 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 232 { 233 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 234 "Kretprobe is accessed from instance under preemptive context"); 235 236 return READ_ONCE(ri->rph->rp); 237 } 238 239 #else /* CONFIG_KRETPROBES */ 240 static inline void arch_prepare_kretprobe(struct kretprobe *rp, 241 struct pt_regs *regs) 242 { 243 } 244 static inline int arch_trampoline_kprobe(struct kprobe *p) 245 { 246 return 0; 247 } 248 #endif /* CONFIG_KRETPROBES */ 249 250 extern struct kretprobe_blackpoint kretprobe_blacklist[]; 251 252 #ifdef CONFIG_KPROBES_SANITY_TEST 253 extern int init_test_probes(void); 254 #else 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 unsigned long addr); 346 347 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 348 349 DEFINE_INSN_CACHE_OPS(optinsn); 350 351 #ifdef CONFIG_SYSCTL 352 extern int sysctl_kprobes_optimization; 353 extern int proc_kprobes_optimization_handler(struct ctl_table *table, 354 int write, void *buffer, 355 size_t *length, loff_t *ppos); 356 #endif 357 extern void wait_for_kprobe_optimizer(void); 358 #else 359 static inline void wait_for_kprobe_optimizer(void) { } 360 #endif /* CONFIG_OPTPROBES */ 361 #ifdef CONFIG_KPROBES_ON_FTRACE 362 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 363 struct ftrace_ops *ops, struct ftrace_regs *fregs); 364 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 365 #endif 366 367 int arch_check_ftrace_location(struct kprobe *p); 368 369 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 370 struct kprobe *get_kprobe(void *addr); 371 372 /* kprobe_running() will just return the current_kprobe on this CPU */ 373 static inline struct kprobe *kprobe_running(void) 374 { 375 return (__this_cpu_read(current_kprobe)); 376 } 377 378 static inline void reset_current_kprobe(void) 379 { 380 __this_cpu_write(current_kprobe, NULL); 381 } 382 383 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 384 { 385 return this_cpu_ptr(&kprobe_ctlblk); 386 } 387 388 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 389 int register_kprobe(struct kprobe *p); 390 void unregister_kprobe(struct kprobe *p); 391 int register_kprobes(struct kprobe **kps, int num); 392 void unregister_kprobes(struct kprobe **kps, int num); 393 unsigned long arch_deref_entry_point(void *); 394 395 int register_kretprobe(struct kretprobe *rp); 396 void unregister_kretprobe(struct kretprobe *rp); 397 int register_kretprobes(struct kretprobe **rps, int num); 398 void unregister_kretprobes(struct kretprobe **rps, int num); 399 400 void kprobe_flush_task(struct task_struct *tk); 401 402 void kprobe_free_init_mem(void); 403 404 int disable_kprobe(struct kprobe *kp); 405 int enable_kprobe(struct kprobe *kp); 406 407 void dump_kprobe(struct kprobe *kp); 408 409 void *alloc_insn_page(void); 410 void free_insn_page(void *page); 411 412 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 413 char *sym); 414 415 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 416 char *type, char *sym); 417 #else /* !CONFIG_KPROBES: */ 418 419 static inline int kprobes_built_in(void) 420 { 421 return 0; 422 } 423 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 424 { 425 return 0; 426 } 427 static inline struct kprobe *get_kprobe(void *addr) 428 { 429 return NULL; 430 } 431 static inline struct kprobe *kprobe_running(void) 432 { 433 return NULL; 434 } 435 static inline int register_kprobe(struct kprobe *p) 436 { 437 return -ENOSYS; 438 } 439 static inline int register_kprobes(struct kprobe **kps, int num) 440 { 441 return -ENOSYS; 442 } 443 static inline void unregister_kprobe(struct kprobe *p) 444 { 445 } 446 static inline void unregister_kprobes(struct kprobe **kps, int num) 447 { 448 } 449 static inline int register_kretprobe(struct kretprobe *rp) 450 { 451 return -ENOSYS; 452 } 453 static inline int register_kretprobes(struct kretprobe **rps, int num) 454 { 455 return -ENOSYS; 456 } 457 static inline void unregister_kretprobe(struct kretprobe *rp) 458 { 459 } 460 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 461 { 462 } 463 static inline void kprobe_flush_task(struct task_struct *tk) 464 { 465 } 466 static inline void kprobe_free_init_mem(void) 467 { 468 } 469 static inline int disable_kprobe(struct kprobe *kp) 470 { 471 return -ENOSYS; 472 } 473 static inline int enable_kprobe(struct kprobe *kp) 474 { 475 return -ENOSYS; 476 } 477 478 static inline bool within_kprobe_blacklist(unsigned long addr) 479 { 480 return true; 481 } 482 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 483 char *type, char *sym) 484 { 485 return -ERANGE; 486 } 487 #endif /* CONFIG_KPROBES */ 488 static inline int disable_kretprobe(struct kretprobe *rp) 489 { 490 return disable_kprobe(&rp->kp); 491 } 492 static inline int enable_kretprobe(struct kretprobe *rp) 493 { 494 return enable_kprobe(&rp->kp); 495 } 496 497 #ifndef CONFIG_KPROBES 498 static inline bool is_kprobe_insn_slot(unsigned long addr) 499 { 500 return false; 501 } 502 #endif 503 #ifndef CONFIG_OPTPROBES 504 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 505 { 506 return false; 507 } 508 #endif 509 510 /* Returns true if kprobes handled the fault */ 511 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 512 unsigned int trap) 513 { 514 if (!kprobes_built_in()) 515 return false; 516 if (user_mode(regs)) 517 return false; 518 /* 519 * To be potentially processing a kprobe fault and to be allowed 520 * to call kprobe_running(), we have to be non-preemptible. 521 */ 522 if (preemptible()) 523 return false; 524 if (!kprobe_running()) 525 return false; 526 return kprobe_fault_handler(regs, trap); 527 } 528 529 #endif /* _LINUX_KPROBES_H */ 530