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 (*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 int kprobe_gone(struct kprobe *p) 109 { 110 return p->flags & KPROBE_FLAG_GONE; 111 } 112 113 /* Is this kprobe disabled ? */ 114 static inline int 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 int kprobe_optimized(struct kprobe *p) 121 { 122 return p->flags & KPROBE_FLAG_OPTIMIZED; 123 } 124 125 /* Is this kprobe uses ftrace ? */ 126 static inline int 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 struct freelist_head freelist; 154 struct kretprobe_holder *rph; 155 }; 156 157 struct kretprobe_instance { 158 union { 159 struct freelist_node freelist; 160 struct rcu_head rcu; 161 }; 162 struct llist_node llist; 163 struct kretprobe_holder *rph; 164 kprobe_opcode_t *ret_addr; 165 void *fp; 166 char data[]; 167 }; 168 169 struct kretprobe_blackpoint { 170 const char *name; 171 void *addr; 172 }; 173 174 struct kprobe_blacklist_entry { 175 struct list_head list; 176 unsigned long start_addr; 177 unsigned long end_addr; 178 }; 179 180 #ifdef CONFIG_KPROBES 181 DECLARE_PER_CPU(struct kprobe *, current_kprobe); 182 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 183 184 /* 185 * For #ifdef avoidance: 186 */ 187 static inline int kprobes_built_in(void) 188 { 189 return 1; 190 } 191 192 extern void kprobe_busy_begin(void); 193 extern void kprobe_busy_end(void); 194 195 #ifdef CONFIG_KRETPROBES 196 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, 197 struct pt_regs *regs); 198 extern int arch_trampoline_kprobe(struct kprobe *p); 199 200 /* If the trampoline handler called from a kprobe, use this version */ 201 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 202 void *trampoline_address, 203 void *frame_pointer); 204 205 static nokprobe_inline 206 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs, 207 void *trampoline_address, 208 void *frame_pointer) 209 { 210 unsigned long ret; 211 /* 212 * Set a dummy kprobe for avoiding kretprobe recursion. 213 * Since kretprobe never runs in kprobe handler, no kprobe must 214 * be running at this point. 215 */ 216 kprobe_busy_begin(); 217 ret = __kretprobe_trampoline_handler(regs, trampoline_address, frame_pointer); 218 kprobe_busy_end(); 219 220 return ret; 221 } 222 223 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri) 224 { 225 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), 226 "Kretprobe is accessed from instance under preemptive context"); 227 228 return READ_ONCE(ri->rph->rp); 229 } 230 231 #else /* CONFIG_KRETPROBES */ 232 static inline void arch_prepare_kretprobe(struct kretprobe *rp, 233 struct pt_regs *regs) 234 { 235 } 236 static inline int arch_trampoline_kprobe(struct kprobe *p) 237 { 238 return 0; 239 } 240 #endif /* CONFIG_KRETPROBES */ 241 242 extern struct kretprobe_blackpoint kretprobe_blacklist[]; 243 244 #ifdef CONFIG_KPROBES_SANITY_TEST 245 extern int init_test_probes(void); 246 #else 247 static inline int init_test_probes(void) 248 { 249 return 0; 250 } 251 #endif /* CONFIG_KPROBES_SANITY_TEST */ 252 253 extern int arch_prepare_kprobe(struct kprobe *p); 254 extern void arch_arm_kprobe(struct kprobe *p); 255 extern void arch_disarm_kprobe(struct kprobe *p); 256 extern int arch_init_kprobes(void); 257 extern void kprobes_inc_nmissed_count(struct kprobe *p); 258 extern bool arch_within_kprobe_blacklist(unsigned long addr); 259 extern int arch_populate_kprobe_blacklist(void); 260 extern bool arch_kprobe_on_func_entry(unsigned long offset); 261 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset); 262 263 extern bool within_kprobe_blacklist(unsigned long addr); 264 extern int kprobe_add_ksym_blacklist(unsigned long entry); 265 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end); 266 267 struct kprobe_insn_cache { 268 struct mutex mutex; 269 void *(*alloc)(void); /* allocate insn page */ 270 void (*free)(void *); /* free insn page */ 271 const char *sym; /* symbol for insn pages */ 272 struct list_head pages; /* list of kprobe_insn_page */ 273 size_t insn_size; /* size of instruction slot */ 274 int nr_garbage; 275 }; 276 277 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 278 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c); 279 extern void __free_insn_slot(struct kprobe_insn_cache *c, 280 kprobe_opcode_t *slot, int dirty); 281 /* sleep-less address checking routine */ 282 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c, 283 unsigned long addr); 284 285 #define DEFINE_INSN_CACHE_OPS(__name) \ 286 extern struct kprobe_insn_cache kprobe_##__name##_slots; \ 287 \ 288 static inline kprobe_opcode_t *get_##__name##_slot(void) \ 289 { \ 290 return __get_insn_slot(&kprobe_##__name##_slots); \ 291 } \ 292 \ 293 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\ 294 { \ 295 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \ 296 } \ 297 \ 298 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 299 { \ 300 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \ 301 } 302 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page" 303 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page" 304 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, 305 unsigned long *value, char *type, char *sym); 306 #else /* __ARCH_WANT_KPROBES_INSN_SLOT */ 307 #define DEFINE_INSN_CACHE_OPS(__name) \ 308 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \ 309 { \ 310 return 0; \ 311 } 312 #endif 313 314 DEFINE_INSN_CACHE_OPS(insn); 315 316 #ifdef CONFIG_OPTPROBES 317 /* 318 * Internal structure for direct jump optimized probe 319 */ 320 struct optimized_kprobe { 321 struct kprobe kp; 322 struct list_head list; /* list for optimizing queue */ 323 struct arch_optimized_insn optinsn; 324 }; 325 326 /* Architecture dependent functions for direct jump optimization */ 327 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); 328 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); 329 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, 330 struct kprobe *orig); 331 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); 332 extern void arch_optimize_kprobes(struct list_head *oplist); 333 extern void arch_unoptimize_kprobes(struct list_head *oplist, 334 struct list_head *done_list); 335 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); 336 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op, 337 unsigned long addr); 338 339 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs); 340 341 DEFINE_INSN_CACHE_OPS(optinsn); 342 343 #ifdef CONFIG_SYSCTL 344 extern int sysctl_kprobes_optimization; 345 extern int proc_kprobes_optimization_handler(struct ctl_table *table, 346 int write, void *buffer, 347 size_t *length, loff_t *ppos); 348 #endif 349 extern void wait_for_kprobe_optimizer(void); 350 #else 351 static inline void wait_for_kprobe_optimizer(void) { } 352 #endif /* CONFIG_OPTPROBES */ 353 #ifdef CONFIG_KPROBES_ON_FTRACE 354 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 355 struct ftrace_ops *ops, struct ftrace_regs *fregs); 356 extern int arch_prepare_kprobe_ftrace(struct kprobe *p); 357 #endif 358 359 int arch_check_ftrace_location(struct kprobe *p); 360 361 /* Get the kprobe at this addr (if any) - called with preemption disabled */ 362 struct kprobe *get_kprobe(void *addr); 363 364 /* kprobe_running() will just return the current_kprobe on this CPU */ 365 static inline struct kprobe *kprobe_running(void) 366 { 367 return (__this_cpu_read(current_kprobe)); 368 } 369 370 static inline void reset_current_kprobe(void) 371 { 372 __this_cpu_write(current_kprobe, NULL); 373 } 374 375 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) 376 { 377 return this_cpu_ptr(&kprobe_ctlblk); 378 } 379 380 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset); 381 int register_kprobe(struct kprobe *p); 382 void unregister_kprobe(struct kprobe *p); 383 int register_kprobes(struct kprobe **kps, int num); 384 void unregister_kprobes(struct kprobe **kps, int num); 385 unsigned long arch_deref_entry_point(void *); 386 387 int register_kretprobe(struct kretprobe *rp); 388 void unregister_kretprobe(struct kretprobe *rp); 389 int register_kretprobes(struct kretprobe **rps, int num); 390 void unregister_kretprobes(struct kretprobe **rps, int num); 391 392 void kprobe_flush_task(struct task_struct *tk); 393 394 void kprobe_free_init_mem(void); 395 396 int disable_kprobe(struct kprobe *kp); 397 int enable_kprobe(struct kprobe *kp); 398 399 void dump_kprobe(struct kprobe *kp); 400 401 void *alloc_insn_page(void); 402 403 void *alloc_optinsn_page(void); 404 void free_optinsn_page(void *page); 405 406 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, 407 char *sym); 408 409 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, 410 char *type, char *sym); 411 #else /* !CONFIG_KPROBES: */ 412 413 static inline int kprobes_built_in(void) 414 { 415 return 0; 416 } 417 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 418 { 419 return 0; 420 } 421 static inline struct kprobe *get_kprobe(void *addr) 422 { 423 return NULL; 424 } 425 static inline struct kprobe *kprobe_running(void) 426 { 427 return NULL; 428 } 429 static inline int register_kprobe(struct kprobe *p) 430 { 431 return -ENOSYS; 432 } 433 static inline int register_kprobes(struct kprobe **kps, int num) 434 { 435 return -ENOSYS; 436 } 437 static inline void unregister_kprobe(struct kprobe *p) 438 { 439 } 440 static inline void unregister_kprobes(struct kprobe **kps, int num) 441 { 442 } 443 static inline int register_kretprobe(struct kretprobe *rp) 444 { 445 return -ENOSYS; 446 } 447 static inline int register_kretprobes(struct kretprobe **rps, int num) 448 { 449 return -ENOSYS; 450 } 451 static inline void unregister_kretprobe(struct kretprobe *rp) 452 { 453 } 454 static inline void unregister_kretprobes(struct kretprobe **rps, int num) 455 { 456 } 457 static inline void kprobe_flush_task(struct task_struct *tk) 458 { 459 } 460 static inline void kprobe_free_init_mem(void) 461 { 462 } 463 static inline int disable_kprobe(struct kprobe *kp) 464 { 465 return -ENOSYS; 466 } 467 static inline int enable_kprobe(struct kprobe *kp) 468 { 469 return -ENOSYS; 470 } 471 472 static inline bool within_kprobe_blacklist(unsigned long addr) 473 { 474 return true; 475 } 476 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, 477 char *type, char *sym) 478 { 479 return -ERANGE; 480 } 481 #endif /* CONFIG_KPROBES */ 482 static inline int disable_kretprobe(struct kretprobe *rp) 483 { 484 return disable_kprobe(&rp->kp); 485 } 486 static inline int enable_kretprobe(struct kretprobe *rp) 487 { 488 return enable_kprobe(&rp->kp); 489 } 490 491 #ifndef CONFIG_KPROBES 492 static inline bool is_kprobe_insn_slot(unsigned long addr) 493 { 494 return false; 495 } 496 #endif 497 #ifndef CONFIG_OPTPROBES 498 static inline bool is_kprobe_optinsn_slot(unsigned long addr) 499 { 500 return false; 501 } 502 #endif 503 504 /* Returns true if kprobes handled the fault */ 505 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, 506 unsigned int trap) 507 { 508 if (!kprobes_built_in()) 509 return false; 510 if (user_mode(regs)) 511 return false; 512 /* 513 * To be potentially processing a kprobe fault and to be allowed 514 * to call kprobe_running(), we have to be non-preemptible. 515 */ 516 if (preemptible()) 517 return false; 518 if (!kprobe_running()) 519 return false; 520 return kprobe_fault_handler(regs, trap); 521 } 522 523 #endif /* _LINUX_KPROBES_H */ 524