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