include/linux/kprobes.h

   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 <asm/kprobes.h>
  31
  32 #ifdef CONFIG_KPROBES
  33
  34 /* kprobe_status settings */
  35 #define KPROBE_HIT_ACTIVE       0x00000001
  36 #define KPROBE_HIT_SS           0x00000002
  37 #define KPROBE_REENTER          0x00000004
  38 #define KPROBE_HIT_SSDONE       0x00000008
  39
  40 #else /* CONFIG_KPROBES */
  41 #include <asm-generic/kprobes.h>
  42 typedef int kprobe_opcode_t;
  43 struct arch_specific_insn {
  44         int dummy;
  45 };
  46 #endif /* CONFIG_KPROBES */
  47
  48 struct kprobe;
  49 struct pt_regs;
  50 struct kretprobe;
  51 struct kretprobe_instance;
  52 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
  53 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
  54                                        unsigned long flags);
  55 typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *,
  56                                        int trapnr);
  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         /*
  85          * ... called if executing addr causes a fault (eg. page fault).
  86          * Return 1 if it handled fault, otherwise kernel will see it.
  87          */
  88         kprobe_fault_handler_t fault_handler;
  89
  90         /* Saved opcode (which has been replaced with breakpoint) */
  91         kprobe_opcode_t opcode;
  92
  93         /* copy of the original instruction */
  94         struct arch_specific_insn ainsn;
  95
  96         /*
  97          * Indicates various status flags.
  98          * Protected by kprobe_mutex after this kprobe is registered.
  99          */
 100         u32 flags;
 101 };
 102
 103 /* Kprobe status flags */
 104 #define KPROBE_FLAG_GONE        1 /* breakpoint has already gone */
 105 #define KPROBE_FLAG_DISABLED    2 /* probe is temporarily disabled */
 106 #define KPROBE_FLAG_OPTIMIZED   4 /*
 107                                    * probe is really optimized.
 108                                    * NOTE:
 109                                    * this flag is only for optimized_kprobe.
 110                                    */
 111 #define KPROBE_FLAG_FTRACE      8 /* probe is using ftrace */
 112
 113 /* Has this kprobe gone ? */
 114 static inline int kprobe_gone(struct kprobe *p)
 115 {
 116         return p->flags & KPROBE_FLAG_GONE;
 117 }
 118
 119 /* Is this kprobe disabled ? */
 120 static inline int kprobe_disabled(struct kprobe *p)
 121 {
 122         return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE);
 123 }
 124
 125 /* Is this kprobe really running optimized path ? */
 126 static inline int kprobe_optimized(struct kprobe *p)
 127 {
 128         return p->flags & KPROBE_FLAG_OPTIMIZED;
 129 }
 130
 131 /* Is this kprobe uses ftrace ? */
 132 static inline int kprobe_ftrace(struct kprobe *p)
 133 {
 134         return p->flags & KPROBE_FLAG_FTRACE;
 135 }
 136
 137 /*
 138  * Function-return probe -
 139  * Note:
 140  * User needs to provide a handler function, and initialize maxactive.
 141  * maxactive - The maximum number of instances of the probed function that
 142  * can be active concurrently.
 143  * nmissed - tracks the number of times the probed function's return was
 144  * ignored, due to maxactive being too low.
 145  *
 146  */
 147 struct kretprobe {
 148         struct kprobe kp;
 149         kretprobe_handler_t handler;
 150         kretprobe_handler_t entry_handler;
 151         int maxactive;
 152         int nmissed;
 153         size_t data_size;
 154         struct hlist_head free_instances;
 155         raw_spinlock_t lock;
 156 };
 157
 158 struct kretprobe_instance {
 159         struct hlist_node hlist;
 160         struct kretprobe *rp;
 161         kprobe_opcode_t *ret_addr;
 162         struct task_struct *task;
 163         void *fp;
 164         char data[0];
 165 };
 166
 167 struct kretprobe_blackpoint {
 168         const char *name;
 169         void *addr;
 170 };
 171
 172 struct kprobe_blacklist_entry {
 173         struct list_head list;
 174         unsigned long start_addr;
 175         unsigned long end_addr;
 176 };
 177
 178 #ifdef CONFIG_KPROBES
 179 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 180 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 181
 182 /*
 183  * For #ifdef avoidance:
 184  */
 185 static inline int kprobes_built_in(void)
 186 {
 187         return 1;
 188 }
 189
 190 #ifdef CONFIG_KRETPROBES
 191 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
 192                                    struct pt_regs *regs);
 193 extern int arch_trampoline_kprobe(struct kprobe *p);
 194 #else /* CONFIG_KRETPROBES */
 195 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 196                                         struct pt_regs *regs)
 197 {
 198 }
 199 static inline int arch_trampoline_kprobe(struct kprobe *p)
 200 {
 201         return 0;
 202 }
 203 #endif /* CONFIG_KRETPROBES */
 204
 205 extern struct kretprobe_blackpoint kretprobe_blacklist[];
 206
 207 static inline void kretprobe_assert(struct kretprobe_instance *ri,
 208         unsigned long orig_ret_address, unsigned long trampoline_address)
 209 {
 210         if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
 211                 printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
 212                                 ri->rp, ri->rp->kp.addr);
 213                 BUG();
 214         }
 215 }
 216
 217 #ifdef CONFIG_KPROBES_SANITY_TEST
 218 extern int init_test_probes(void);
 219 #else
 220 static inline int init_test_probes(void)
 221 {
 222         return 0;
 223 }
 224 #endif /* CONFIG_KPROBES_SANITY_TEST */
 225
 226 extern int arch_prepare_kprobe(struct kprobe *p);
 227 extern void arch_arm_kprobe(struct kprobe *p);
 228 extern void arch_disarm_kprobe(struct kprobe *p);
 229 extern int arch_init_kprobes(void);
 230 extern void show_registers(struct pt_regs *regs);
 231 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 232 extern bool arch_within_kprobe_blacklist(unsigned long addr);
 233 extern int arch_populate_kprobe_blacklist(void);
 234 extern bool arch_kprobe_on_func_entry(unsigned long offset);
 235 extern bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
 236
 237 extern bool within_kprobe_blacklist(unsigned long addr);
 238 extern int kprobe_add_ksym_blacklist(unsigned long entry);
 239 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
 240
 241 struct kprobe_insn_cache {
 242         struct mutex mutex;
 243         void *(*alloc)(void);   /* allocate insn page */
 244         void (*free)(void *);   /* free insn page */
 245         struct list_head pages; /* list of kprobe_insn_page */
 246         size_t insn_size;       /* size of instruction slot */
 247         int nr_garbage;
 248 };
 249
 250 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 251 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
 252 extern void __free_insn_slot(struct kprobe_insn_cache *c,
 253                              kprobe_opcode_t *slot, int dirty);
 254 /* sleep-less address checking routine  */
 255 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
 256                                 unsigned long addr);
 257
 258 #define DEFINE_INSN_CACHE_OPS(__name)                                   \
 259 extern struct kprobe_insn_cache kprobe_##__name##_slots;                \
 260                                                                         \
 261 static inline kprobe_opcode_t *get_##__name##_slot(void)                \
 262 {                                                                       \
 263         return __get_insn_slot(&kprobe_##__name##_slots);               \
 264 }                                                                       \
 265                                                                         \
 266 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
 267 {                                                                       \
 268         __free_insn_slot(&kprobe_##__name##_slots, slot, dirty);        \
 269 }                                                                       \
 270                                                                         \
 271 static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \
 272 {                                                                       \
 273         return __is_insn_slot_addr(&kprobe_##__name##_slots, addr);     \
 274 }
 275 #else /* __ARCH_WANT_KPROBES_INSN_SLOT */
 276 #define DEFINE_INSN_CACHE_OPS(__name)                                   \
 277 static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \
 278 {                                                                       \
 279         return 0;                                                       \
 280 }
 281 #endif
 282
 283 DEFINE_INSN_CACHE_OPS(insn);
 284
 285 #ifdef CONFIG_OPTPROBES
 286 /*
 287  * Internal structure for direct jump optimized probe
 288  */
 289 struct optimized_kprobe {
 290         struct kprobe kp;
 291         struct list_head list;  /* list for optimizing queue */
 292         struct arch_optimized_insn optinsn;
 293 };
 294
 295 /* Architecture dependent functions for direct jump optimization */
 296 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
 297 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
 298 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
 299                                          struct kprobe *orig);
 300 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
 301 extern void arch_optimize_kprobes(struct list_head *oplist);
 302 extern void arch_unoptimize_kprobes(struct list_head *oplist,
 303                                     struct list_head *done_list);
 304 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
 305 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
 306                                         unsigned long addr);
 307
 308 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
 309
 310 DEFINE_INSN_CACHE_OPS(optinsn);
 311
 312 #ifdef CONFIG_SYSCTL
 313 extern int sysctl_kprobes_optimization;
 314 extern int proc_kprobes_optimization_handler(struct ctl_table *table,
 315                                              int write, void __user *buffer,
 316                                              size_t *length, loff_t *ppos);
 317 #endif
 318 extern void wait_for_kprobe_optimizer(void);
 319 #else
 320 static inline void wait_for_kprobe_optimizer(void) { }
 321 #endif /* CONFIG_OPTPROBES */
 322 #ifdef CONFIG_KPROBES_ON_FTRACE
 323 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 324                                   struct ftrace_ops *ops, struct pt_regs *regs);
 325 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
 326 #endif
 327
 328 int arch_check_ftrace_location(struct kprobe *p);
 329
 330 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 331 struct kprobe *get_kprobe(void *addr);
 332 void kretprobe_hash_lock(struct task_struct *tsk,
 333                          struct hlist_head **head, unsigned long *flags);
 334 void kretprobe_hash_unlock(struct task_struct *tsk, unsigned long *flags);
 335 struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
 336
 337 /* kprobe_running() will just return the current_kprobe on this CPU */
 338 static inline struct kprobe *kprobe_running(void)
 339 {
 340         return (__this_cpu_read(current_kprobe));
 341 }
 342
 343 static inline void reset_current_kprobe(void)
 344 {
 345         __this_cpu_write(current_kprobe, NULL);
 346 }
 347
 348 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 349 {
 350         return this_cpu_ptr(&kprobe_ctlblk);
 351 }
 352
 353 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
 354 int register_kprobe(struct kprobe *p);
 355 void unregister_kprobe(struct kprobe *p);
 356 int register_kprobes(struct kprobe **kps, int num);
 357 void unregister_kprobes(struct kprobe **kps, int num);
 358 unsigned long arch_deref_entry_point(void *);
 359
 360 int register_kretprobe(struct kretprobe *rp);
 361 void unregister_kretprobe(struct kretprobe *rp);
 362 int register_kretprobes(struct kretprobe **rps, int num);
 363 void unregister_kretprobes(struct kretprobe **rps, int num);
 364
 365 void kprobe_flush_task(struct task_struct *tk);
 366 void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
 367
 368 int disable_kprobe(struct kprobe *kp);
 369 int enable_kprobe(struct kprobe *kp);
 370
 371 void dump_kprobe(struct kprobe *kp);
 372
 373 void *alloc_insn_page(void);
 374 void free_insn_page(void *page);
 375
 376 #else /* !CONFIG_KPROBES: */
 377
 378 static inline int kprobes_built_in(void)
 379 {
 380         return 0;
 381 }
 382 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 383 {
 384         return 0;
 385 }
 386 static inline struct kprobe *get_kprobe(void *addr)
 387 {
 388         return NULL;
 389 }
 390 static inline struct kprobe *kprobe_running(void)
 391 {
 392         return NULL;
 393 }
 394 static inline int register_kprobe(struct kprobe *p)
 395 {
 396         return -ENOSYS;
 397 }
 398 static inline int register_kprobes(struct kprobe **kps, int num)
 399 {
 400         return -ENOSYS;
 401 }
 402 static inline void unregister_kprobe(struct kprobe *p)
 403 {
 404 }
 405 static inline void unregister_kprobes(struct kprobe **kps, int num)
 406 {
 407 }
 408 static inline int register_kretprobe(struct kretprobe *rp)
 409 {
 410         return -ENOSYS;
 411 }
 412 static inline int register_kretprobes(struct kretprobe **rps, int num)
 413 {
 414         return -ENOSYS;
 415 }
 416 static inline void unregister_kretprobe(struct kretprobe *rp)
 417 {
 418 }
 419 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
 420 {
 421 }
 422 static inline void kprobe_flush_task(struct task_struct *tk)
 423 {
 424 }
 425 static inline int disable_kprobe(struct kprobe *kp)
 426 {
 427         return -ENOSYS;
 428 }
 429 static inline int enable_kprobe(struct kprobe *kp)
 430 {
 431         return -ENOSYS;
 432 }
 433
 434 static inline bool within_kprobe_blacklist(unsigned long addr)
 435 {
 436         return true;
 437 }
 438 #endif /* CONFIG_KPROBES */
 439 static inline int disable_kretprobe(struct kretprobe *rp)
 440 {
 441         return disable_kprobe(&rp->kp);
 442 }
 443 static inline int enable_kretprobe(struct kretprobe *rp)
 444 {
 445         return enable_kprobe(&rp->kp);
 446 }
 447
 448 #ifndef CONFIG_KPROBES
 449 static inline bool is_kprobe_insn_slot(unsigned long addr)
 450 {
 451         return false;
 452 }
 453 #endif
 454 #ifndef CONFIG_OPTPROBES
 455 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
 456 {
 457         return false;
 458 }
 459 #endif
 460
 461 /* Returns true if kprobes handled the fault */
 462 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
 463                                               unsigned int trap)
 464 {
 465         if (!kprobes_built_in())
 466                 return false;
 467         if (user_mode(regs))
 468                 return false;
 469         /*
 470          * To be potentially processing a kprobe fault and to be allowed
 471          * to call kprobe_running(), we have to be non-preemptible.
 472          */
 473         if (preemptible())
 474                 return false;
 475         if (!kprobe_running())
 476                 return false;
 477         return kprobe_fault_handler(regs, trap);
 478 }
 479
 480 #endif /* _LINUX_KPROBES_H */