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 ? */
kprobe_gone(struct kprobe * p)107 static inline bool kprobe_gone(struct kprobe *p)
108 {
109 return p->flags & KPROBE_FLAG_GONE;
110 }
111
112 /* Is this kprobe disabled ? */
kprobe_disabled(struct kprobe * p)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 ? */
kprobe_optimized(struct kprobe * p)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 ? */
kprobe_ftrace(struct kprobe * p)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 #define KRETPROBE_MAX_DATA_SIZE 4096
157
158 struct kretprobe_instance {
159 union {
160 struct freelist_node freelist;
161 struct rcu_head rcu;
162 };
163 struct llist_node llist;
164 struct kretprobe_holder *rph;
165 kprobe_opcode_t *ret_addr;
166 void *fp;
167 char data[];
168 };
169
170 struct kretprobe_blackpoint {
171 const char *name;
172 void *addr;
173 };
174
175 struct kprobe_blacklist_entry {
176 struct list_head list;
177 unsigned long start_addr;
178 unsigned long end_addr;
179 };
180
181 #ifdef CONFIG_KPROBES
182 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
183 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
184
185 extern void kprobe_busy_begin(void);
186 extern void kprobe_busy_end(void);
187
188 #ifdef CONFIG_KRETPROBES
189 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
190 struct pt_regs *regs);
191 extern int arch_trampoline_kprobe(struct kprobe *p);
192
193 void arch_kretprobe_fixup_return(struct pt_regs *regs,
194 kprobe_opcode_t *correct_ret_addr);
195
196 void __kretprobe_trampoline(void);
197 /*
198 * Since some architecture uses structured function pointer,
199 * use dereference_function_descriptor() to get real function address.
200 */
kretprobe_trampoline_addr(void)201 static nokprobe_inline void *kretprobe_trampoline_addr(void)
202 {
203 return dereference_kernel_function_descriptor(__kretprobe_trampoline);
204 }
205
206 /* If the trampoline handler called from a kprobe, use this version */
207 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
208 void *frame_pointer);
209
210 static nokprobe_inline
kretprobe_trampoline_handler(struct pt_regs * regs,void * frame_pointer)211 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
212 void *frame_pointer)
213 {
214 unsigned long ret;
215 /*
216 * Set a dummy kprobe for avoiding kretprobe recursion.
217 * Since kretprobe never runs in kprobe handler, no kprobe must
218 * be running at this point.
219 */
220 kprobe_busy_begin();
221 ret = __kretprobe_trampoline_handler(regs, frame_pointer);
222 kprobe_busy_end();
223
224 return ret;
225 }
226
get_kretprobe(struct kretprobe_instance * ri)227 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
228 {
229 RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
230 "Kretprobe is accessed from instance under preemptive context");
231
232 return READ_ONCE(ri->rph->rp);
233 }
234
235 #else /* !CONFIG_KRETPROBES */
arch_prepare_kretprobe(struct kretprobe * rp,struct pt_regs * regs)236 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
237 struct pt_regs *regs)
238 {
239 }
arch_trampoline_kprobe(struct kprobe * p)240 static inline int arch_trampoline_kprobe(struct kprobe *p)
241 {
242 return 0;
243 }
244 #endif /* CONFIG_KRETPROBES */
245
246 /* Markers of '_kprobe_blacklist' section */
247 extern unsigned long __start_kprobe_blacklist[];
248 extern unsigned long __stop_kprobe_blacklist[];
249
250 extern struct kretprobe_blackpoint kretprobe_blacklist[];
251
252 #ifdef CONFIG_KPROBES_SANITY_TEST
253 extern int init_test_probes(void);
254 #else /* !CONFIG_KPROBES_SANITY_TEST */
init_test_probes(void)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 kprobe_opcode_t *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 /* CONFIG_SYSCTL */
357 extern void wait_for_kprobe_optimizer(void);
358 #else /* !CONFIG_OPTPROBES */
wait_for_kprobe_optimizer(void)359 static inline void wait_for_kprobe_optimizer(void) { }
360 #endif /* CONFIG_OPTPROBES */
361
362 #ifdef CONFIG_KPROBES_ON_FTRACE
363 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
364 struct ftrace_ops *ops, struct ftrace_regs *fregs);
365 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
366 #else
arch_prepare_kprobe_ftrace(struct kprobe * p)367 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
368 {
369 return -EINVAL;
370 }
371 #endif /* CONFIG_KPROBES_ON_FTRACE */
372
373 /* Get the kprobe at this addr (if any) - called with preemption disabled */
374 struct kprobe *get_kprobe(void *addr);
375
376 /* kprobe_running() will just return the current_kprobe on this CPU */
kprobe_running(void)377 static inline struct kprobe *kprobe_running(void)
378 {
379 return __this_cpu_read(current_kprobe);
380 }
381
reset_current_kprobe(void)382 static inline void reset_current_kprobe(void)
383 {
384 __this_cpu_write(current_kprobe, NULL);
385 }
386
get_kprobe_ctlblk(void)387 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
388 {
389 return this_cpu_ptr(&kprobe_ctlblk);
390 }
391
392 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
393 int register_kprobe(struct kprobe *p);
394 void unregister_kprobe(struct kprobe *p);
395 int register_kprobes(struct kprobe **kps, int num);
396 void unregister_kprobes(struct kprobe **kps, int num);
397
398 int register_kretprobe(struct kretprobe *rp);
399 void unregister_kretprobe(struct kretprobe *rp);
400 int register_kretprobes(struct kretprobe **rps, int num);
401 void unregister_kretprobes(struct kretprobe **rps, int num);
402
403 void kprobe_flush_task(struct task_struct *tk);
404
405 void kprobe_free_init_mem(void);
406
407 int disable_kprobe(struct kprobe *kp);
408 int enable_kprobe(struct kprobe *kp);
409
410 void dump_kprobe(struct kprobe *kp);
411
412 void *alloc_insn_page(void);
413
414 void *alloc_optinsn_page(void);
415 void free_optinsn_page(void *page);
416
417 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
418 char *sym);
419
420 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
421 char *type, char *sym);
422 #else /* !CONFIG_KPROBES: */
423
kprobe_fault_handler(struct pt_regs * regs,int trapnr)424 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
425 {
426 return 0;
427 }
get_kprobe(void * addr)428 static inline struct kprobe *get_kprobe(void *addr)
429 {
430 return NULL;
431 }
kprobe_running(void)432 static inline struct kprobe *kprobe_running(void)
433 {
434 return NULL;
435 }
register_kprobe(struct kprobe * p)436 static inline int register_kprobe(struct kprobe *p)
437 {
438 return -EOPNOTSUPP;
439 }
register_kprobes(struct kprobe ** kps,int num)440 static inline int register_kprobes(struct kprobe **kps, int num)
441 {
442 return -EOPNOTSUPP;
443 }
unregister_kprobe(struct kprobe * p)444 static inline void unregister_kprobe(struct kprobe *p)
445 {
446 }
unregister_kprobes(struct kprobe ** kps,int num)447 static inline void unregister_kprobes(struct kprobe **kps, int num)
448 {
449 }
register_kretprobe(struct kretprobe * rp)450 static inline int register_kretprobe(struct kretprobe *rp)
451 {
452 return -EOPNOTSUPP;
453 }
register_kretprobes(struct kretprobe ** rps,int num)454 static inline int register_kretprobes(struct kretprobe **rps, int num)
455 {
456 return -EOPNOTSUPP;
457 }
unregister_kretprobe(struct kretprobe * rp)458 static inline void unregister_kretprobe(struct kretprobe *rp)
459 {
460 }
unregister_kretprobes(struct kretprobe ** rps,int num)461 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
462 {
463 }
kprobe_flush_task(struct task_struct * tk)464 static inline void kprobe_flush_task(struct task_struct *tk)
465 {
466 }
kprobe_free_init_mem(void)467 static inline void kprobe_free_init_mem(void)
468 {
469 }
disable_kprobe(struct kprobe * kp)470 static inline int disable_kprobe(struct kprobe *kp)
471 {
472 return -EOPNOTSUPP;
473 }
enable_kprobe(struct kprobe * kp)474 static inline int enable_kprobe(struct kprobe *kp)
475 {
476 return -EOPNOTSUPP;
477 }
478
within_kprobe_blacklist(unsigned long addr)479 static inline bool within_kprobe_blacklist(unsigned long addr)
480 {
481 return true;
482 }
kprobe_get_kallsym(unsigned int symnum,unsigned long * value,char * type,char * sym)483 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
484 char *type, char *sym)
485 {
486 return -ERANGE;
487 }
488 #endif /* CONFIG_KPROBES */
489
disable_kretprobe(struct kretprobe * rp)490 static inline int disable_kretprobe(struct kretprobe *rp)
491 {
492 return disable_kprobe(&rp->kp);
493 }
enable_kretprobe(struct kretprobe * rp)494 static inline int enable_kretprobe(struct kretprobe *rp)
495 {
496 return enable_kprobe(&rp->kp);
497 }
498
499 #ifndef CONFIG_KPROBES
is_kprobe_insn_slot(unsigned long addr)500 static inline bool is_kprobe_insn_slot(unsigned long addr)
501 {
502 return false;
503 }
504 #endif /* !CONFIG_KPROBES */
505
506 #ifndef CONFIG_OPTPROBES
is_kprobe_optinsn_slot(unsigned long addr)507 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
508 {
509 return false;
510 }
511 #endif /* !CONFIG_OPTPROBES */
512
513 #ifdef CONFIG_KRETPROBES
is_kretprobe_trampoline(unsigned long addr)514 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
515 {
516 return (void *)addr == kretprobe_trampoline_addr();
517 }
518
519 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
520 struct llist_node **cur);
521 #else
is_kretprobe_trampoline(unsigned long addr)522 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
523 {
524 return false;
525 }
526
527 static nokprobe_inline
kretprobe_find_ret_addr(struct task_struct * tsk,void * fp,struct llist_node ** cur)528 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
529 struct llist_node **cur)
530 {
531 return 0;
532 }
533 #endif
534
535 /* Returns true if kprobes handled the fault */
kprobe_page_fault(struct pt_regs * regs,unsigned int trap)536 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
537 unsigned int trap)
538 {
539 if (!IS_ENABLED(CONFIG_KPROBES))
540 return false;
541 if (user_mode(regs))
542 return false;
543 /*
544 * To be potentially processing a kprobe fault and to be allowed
545 * to call kprobe_running(), we have to be non-preemptible.
546 */
547 if (preemptible())
548 return false;
549 if (!kprobe_running())
550 return false;
551 return kprobe_fault_handler(regs, trap);
552 }
553
554 #endif /* _LINUX_KPROBES_H */
555