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/objpool.h>
30 #include <linux/rethook.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 #define KPROBE_FLAG_ON_FUNC_ENTRY 16 /* probe is on the function entry */
106
107 /* Has this kprobe gone ? */
108 static inline bool kprobe_gone(struct kprobe *p)
109 {
110 return p->flags & KPROBE_FLAG_GONE;
111 }
112
113 /* Is this kprobe disabled ? */
114 static inline bool 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 bool kprobe_optimized(struct kprobe *p)
121 {
122 return p->flags & KPROBE_FLAG_OPTIMIZED;
123 }
124
125 /* Is this kprobe uses ftrace ? */
126 static inline bool 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 __rcu *rp;
143 struct objpool_head pool;
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 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
154 struct rethook *rh;
155 #else
156 struct kretprobe_holder *rph;
157 #endif
158 };
159
160 #define KRETPROBE_MAX_DATA_SIZE 4096
161
162 struct kretprobe_instance {
163 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
164 struct rethook_node node;
165 #else
166 struct rcu_head rcu;
167 struct llist_node llist;
168 struct kretprobe_holder *rph;
169 kprobe_opcode_t *ret_addr;
170 void *fp;
171 #endif
172 char data[];
173 };
174
175 struct kretprobe_blackpoint {
176 const char *name;
177 void *addr;
178 };
179
180 struct kprobe_blacklist_entry {
181 struct list_head list;
182 unsigned long start_addr;
183 unsigned long end_addr;
184 };
185
186 #ifdef CONFIG_KPROBES
187 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
188 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
189
190 extern void kprobe_busy_begin(void);
191 extern void kprobe_busy_end(void);
192
193 #ifdef CONFIG_KRETPROBES
194 /* Check whether @p is used for implementing a trampoline. */
195 extern int arch_trampoline_kprobe(struct kprobe *p);
196
197 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
198 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
199 {
200 /* rethook::data is non-changed field, so that you can access it freely. */
201 return (struct kretprobe *)ri->node.rethook->data;
202 }
203 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
204 {
205 return ri->node.ret_addr;
206 }
207 #else
208 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
209 struct pt_regs *regs);
210 void arch_kretprobe_fixup_return(struct pt_regs *regs,
211 kprobe_opcode_t *correct_ret_addr);
212
213 void __kretprobe_trampoline(void);
214 /*
215 * Since some architecture uses structured function pointer,
216 * use dereference_function_descriptor() to get real function address.
217 */
218 static nokprobe_inline void *kretprobe_trampoline_addr(void)
219 {
220 return dereference_kernel_function_descriptor(__kretprobe_trampoline);
221 }
222
223 /* If the trampoline handler called from a kprobe, use this version */
224 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
225 void *frame_pointer);
226
227 static nokprobe_inline
228 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
229 void *frame_pointer)
230 {
231 unsigned long ret;
232 /*
233 * Set a dummy kprobe for avoiding kretprobe recursion.
234 * Since kretprobe never runs in kprobe handler, no kprobe must
235 * be running at this point.
236 */
237 kprobe_busy_begin();
238 ret = __kretprobe_trampoline_handler(regs, frame_pointer);
239 kprobe_busy_end();
240
241 return ret;
242 }
243
244 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
245 {
246 return rcu_dereference_check(ri->rph->rp, rcu_read_lock_any_held());
247 }
248
249 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
250 {
251 return (unsigned long)ri->ret_addr;
252 }
253 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */
254
255 #else /* !CONFIG_KRETPROBES */
256 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
257 struct pt_regs *regs)
258 {
259 }
260 static inline int arch_trampoline_kprobe(struct kprobe *p)
261 {
262 return 0;
263 }
264 #endif /* CONFIG_KRETPROBES */
265
266 /* Markers of '_kprobe_blacklist' section */
267 extern unsigned long __start_kprobe_blacklist[];
268 extern unsigned long __stop_kprobe_blacklist[];
269
270 extern struct kretprobe_blackpoint kretprobe_blacklist[];
271
272 #ifdef CONFIG_KPROBES_SANITY_TEST
273 extern int init_test_probes(void);
274 #else /* !CONFIG_KPROBES_SANITY_TEST */
275 static inline int init_test_probes(void)
276 {
277 return 0;
278 }
279 #endif /* CONFIG_KPROBES_SANITY_TEST */
280
281 extern int arch_prepare_kprobe(struct kprobe *p);
282 extern void arch_arm_kprobe(struct kprobe *p);
283 extern void arch_disarm_kprobe(struct kprobe *p);
284 extern int arch_init_kprobes(void);
285 extern void kprobes_inc_nmissed_count(struct kprobe *p);
286 extern bool arch_within_kprobe_blacklist(unsigned long addr);
287 extern int arch_populate_kprobe_blacklist(void);
288 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
289
290 extern bool within_kprobe_blacklist(unsigned long addr);
291 extern int kprobe_add_ksym_blacklist(unsigned long entry);
292 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
293
294 struct kprobe_insn_cache {
295 struct mutex mutex;
296 void *(*alloc)(void); /* allocate insn page */
297 void (*free)(void *); /* free insn page */
298 const char *sym; /* symbol for insn pages */
299 struct list_head pages; /* list of kprobe_insn_page */
300 size_t insn_size; /* size of instruction slot */
301 int nr_garbage;
302 };
303
304 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
305 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
306 extern void __free_insn_slot(struct kprobe_insn_cache *c,
307 kprobe_opcode_t *slot, int dirty);
308 /* sleep-less address checking routine */
309 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
310 unsigned long addr);
311
312 #define DEFINE_INSN_CACHE_OPS(__name) \
313 extern struct kprobe_insn_cache kprobe_##__name##_slots; \
314 \
315 static inline kprobe_opcode_t *get_##__name##_slot(void) \
316 { \
317 return __get_insn_slot(&kprobe_##__name##_slots); \
318 } \
319 \
320 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
321 { \
322 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \
323 } \
324 \
325 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \
326 { \
327 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \
328 }
329 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page"
330 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page"
331 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
332 unsigned long *value, char *type, char *sym);
333 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */
334 #define DEFINE_INSN_CACHE_OPS(__name) \
335 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \
336 { \
337 return 0; \
338 }
339 #endif
340
341 DEFINE_INSN_CACHE_OPS(insn);
342
343 #ifdef CONFIG_OPTPROBES
344 /*
345 * Internal structure for direct jump optimized probe
346 */
347 struct optimized_kprobe {
348 struct kprobe kp;
349 struct list_head list; /* list for optimizing queue */
350 struct arch_optimized_insn optinsn;
351 };
352
353 /* Architecture dependent functions for direct jump optimization */
354 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
355 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
356 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
357 struct kprobe *orig);
358 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
359 extern void arch_optimize_kprobes(struct list_head *oplist);
360 extern void arch_unoptimize_kprobes(struct list_head *oplist,
361 struct list_head *done_list);
362 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
363 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
364 kprobe_opcode_t *addr);
365
366 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
367
368 DEFINE_INSN_CACHE_OPS(optinsn);
369
370 extern void wait_for_kprobe_optimizer(void);
371 bool optprobe_queued_unopt(struct optimized_kprobe *op);
372 bool kprobe_disarmed(struct kprobe *p);
373 #else /* !CONFIG_OPTPROBES */
374 static inline void wait_for_kprobe_optimizer(void) { }
375 #endif /* CONFIG_OPTPROBES */
376
377 #ifdef CONFIG_KPROBES_ON_FTRACE
378 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
379 struct ftrace_ops *ops, struct ftrace_regs *fregs);
380 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
381 /* Set when ftrace has been killed: kprobes on ftrace must be disabled for safety */
382 extern bool kprobe_ftrace_disabled __read_mostly;
383 extern void kprobe_ftrace_kill(void);
384 #else
385 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
386 {
387 return -EINVAL;
388 }
389 static inline void kprobe_ftrace_kill(void) {}
390 #endif /* CONFIG_KPROBES_ON_FTRACE */
391
392 /* Get the kprobe at this addr (if any) - called with preemption disabled */
393 struct kprobe *get_kprobe(void *addr);
394
395 /* kprobe_running() will just return the current_kprobe on this CPU */
396 static inline struct kprobe *kprobe_running(void)
397 {
398 return __this_cpu_read(current_kprobe);
399 }
400
401 static inline void reset_current_kprobe(void)
402 {
403 __this_cpu_write(current_kprobe, NULL);
404 }
405
406 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
407 {
408 return this_cpu_ptr(&kprobe_ctlblk);
409 }
410
411 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
412 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry);
413
414 int register_kprobe(struct kprobe *p);
415 void unregister_kprobe(struct kprobe *p);
416 int register_kprobes(struct kprobe **kps, int num);
417 void unregister_kprobes(struct kprobe **kps, int num);
418
419 int register_kretprobe(struct kretprobe *rp);
420 void unregister_kretprobe(struct kretprobe *rp);
421 int register_kretprobes(struct kretprobe **rps, int num);
422 void unregister_kretprobes(struct kretprobe **rps, int num);
423
424 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
425 #define kprobe_flush_task(tk) do {} while (0)
426 #else
427 void kprobe_flush_task(struct task_struct *tk);
428 #endif
429
430 void kprobe_free_init_mem(void);
431
432 int disable_kprobe(struct kprobe *kp);
433 int enable_kprobe(struct kprobe *kp);
434
435 void dump_kprobe(struct kprobe *kp);
436
437 void *alloc_insn_page(void);
438
439 void *alloc_optinsn_page(void);
440 void free_optinsn_page(void *page);
441
442 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
443 char *sym);
444
445 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
446 char *type, char *sym);
447
448 int kprobe_exceptions_notify(struct notifier_block *self,
449 unsigned long val, void *data);
450
451 #else /* !CONFIG_KPROBES: */
452
453 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
454 {
455 return 0;
456 }
457 static inline struct kprobe *get_kprobe(void *addr)
458 {
459 return NULL;
460 }
461 static inline struct kprobe *kprobe_running(void)
462 {
463 return NULL;
464 }
465 #define kprobe_busy_begin() do {} while (0)
466 #define kprobe_busy_end() do {} while (0)
467
468 static inline int register_kprobe(struct kprobe *p)
469 {
470 return -EOPNOTSUPP;
471 }
472 static inline int register_kprobes(struct kprobe **kps, int num)
473 {
474 return -EOPNOTSUPP;
475 }
476 static inline void unregister_kprobe(struct kprobe *p)
477 {
478 }
479 static inline void unregister_kprobes(struct kprobe **kps, int num)
480 {
481 }
482 static inline int register_kretprobe(struct kretprobe *rp)
483 {
484 return -EOPNOTSUPP;
485 }
486 static inline int register_kretprobes(struct kretprobe **rps, int num)
487 {
488 return -EOPNOTSUPP;
489 }
490 static inline void unregister_kretprobe(struct kretprobe *rp)
491 {
492 }
493 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
494 {
495 }
496 static inline void kprobe_flush_task(struct task_struct *tk)
497 {
498 }
499 static inline void kprobe_free_init_mem(void)
500 {
501 }
502 static inline void kprobe_ftrace_kill(void)
503 {
504 }
505 static inline int disable_kprobe(struct kprobe *kp)
506 {
507 return -EOPNOTSUPP;
508 }
509 static inline int enable_kprobe(struct kprobe *kp)
510 {
511 return -EOPNOTSUPP;
512 }
513
514 static inline bool within_kprobe_blacklist(unsigned long addr)
515 {
516 return true;
517 }
518 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
519 char *type, char *sym)
520 {
521 return -ERANGE;
522 }
523 #endif /* CONFIG_KPROBES */
524
525 static inline int disable_kretprobe(struct kretprobe *rp)
526 {
527 return disable_kprobe(&rp->kp);
528 }
529 static inline int enable_kretprobe(struct kretprobe *rp)
530 {
531 return enable_kprobe(&rp->kp);
532 }
533
534 #ifndef CONFIG_KPROBES
535 static inline bool is_kprobe_insn_slot(unsigned long addr)
536 {
537 return false;
538 }
539 #endif /* !CONFIG_KPROBES */
540
541 #ifndef CONFIG_OPTPROBES
542 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
543 {
544 return false;
545 }
546 #endif /* !CONFIG_OPTPROBES */
547
548 #ifdef CONFIG_KRETPROBES
549 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
550 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
551 {
552 return is_rethook_trampoline(addr);
553 }
554
555 static nokprobe_inline
556 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
557 struct llist_node **cur)
558 {
559 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
560 }
561 #else
562 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
563 {
564 return (void *)addr == kretprobe_trampoline_addr();
565 }
566
567 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
568 struct llist_node **cur);
569 #endif
570 #else
571 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
572 {
573 return false;
574 }
575
576 static nokprobe_inline
577 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
578 struct llist_node **cur)
579 {
580 return 0;
581 }
582 #endif
583
584 /* Returns true if kprobes handled the fault */
585 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
586 unsigned int trap)
587 {
588 if (!IS_ENABLED(CONFIG_KPROBES))
589 return false;
590 if (user_mode(regs))
591 return false;
592 /*
593 * To be potentially processing a kprobe fault and to be allowed
594 * to call kprobe_running(), we have to be non-preemptible.
595 */
596 if (preemptible())
597 return false;
598 if (!kprobe_running())
599 return false;
600 return kprobe_fault_handler(regs, trap);
601 }
602
603 #endif /* _LINUX_KPROBES_H */
604
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