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>
43typedef int kprobe_opcode_t;
44struct arch_specific_insn {
45	int dummy;
46};
47#endif /* CONFIG_KPROBES */
48
49struct kprobe;
50struct pt_regs;
51struct kretprobe;
52struct kretprobe_instance;
53typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
54typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
55				       unsigned long flags);
56typedef int (*kretprobe_handler_t) (struct kretprobe_instance *,
57				    struct pt_regs *);
58
59struct 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 ? */
108static inline bool kprobe_gone(struct kprobe *p)
109{
110	return p->flags & KPROBE_FLAG_GONE;
111}
112
113/* Is this kprobe disabled ? */
114static 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 ? */
120static inline bool kprobe_optimized(struct kprobe *p)
121{
122	return p->flags & KPROBE_FLAG_OPTIMIZED;
123}
124
125/* Is this kprobe uses ftrace ? */
126static 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 */
141struct kretprobe_holder {
142	struct kretprobe __rcu *rp;
143	struct objpool_head	pool;
144};
145
146struct 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
162struct 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
175struct kretprobe_blackpoint {
176	const char *name;
177	void *addr;
178};
179
180struct kprobe_blacklist_entry {
181	struct list_head list;
182	unsigned long start_addr;
183	unsigned long end_addr;
184};
185
186#ifdef CONFIG_KPROBES
187DECLARE_PER_CPU(struct kprobe *, current_kprobe);
188DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
189
190extern void kprobe_busy_begin(void);
191extern void kprobe_busy_end(void);
192
193#ifdef CONFIG_KRETPROBES
194/* Check whether @p is used for implementing a trampoline. */
195extern int arch_trampoline_kprobe(struct kprobe *p);
196
197#ifdef CONFIG_KRETPROBE_ON_RETHOOK
198static 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}
203static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
204{
205	return ri->node.ret_addr;
206}
207#else
208extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
209				   struct pt_regs *regs);
210void arch_kretprobe_fixup_return(struct pt_regs *regs,
211				 kprobe_opcode_t *correct_ret_addr);
212
213void __kretprobe_trampoline(void);
214/*
215 * Since some architecture uses structured function pointer,
216 * use dereference_function_descriptor() to get real function address.
217 */
218static 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 */
224unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
225					     void *frame_pointer);
226
227static nokprobe_inline
228unsigned 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
244static 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
249static 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 */
256static inline void arch_prepare_kretprobe(struct kretprobe *rp,
257					struct pt_regs *regs)
258{
259}
260static inline int arch_trampoline_kprobe(struct kprobe *p)
261{
262	return 0;
263}
264#endif /* CONFIG_KRETPROBES */
265
266/* Markers of '_kprobe_blacklist' section */
267extern unsigned long __start_kprobe_blacklist[];
268extern unsigned long __stop_kprobe_blacklist[];
269
270extern struct kretprobe_blackpoint kretprobe_blacklist[];
271
272#ifdef CONFIG_KPROBES_SANITY_TEST
273extern int init_test_probes(void);
274#else /* !CONFIG_KPROBES_SANITY_TEST */
275static inline int init_test_probes(void)
276{
277	return 0;
278}
279#endif /* CONFIG_KPROBES_SANITY_TEST */
280
281extern int arch_prepare_kprobe(struct kprobe *p);
282extern void arch_arm_kprobe(struct kprobe *p);
283extern void arch_disarm_kprobe(struct kprobe *p);
284extern int arch_init_kprobes(void);
285extern void kprobes_inc_nmissed_count(struct kprobe *p);
286extern bool arch_within_kprobe_blacklist(unsigned long addr);
287extern int arch_populate_kprobe_blacklist(void);
288extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
289
290extern bool within_kprobe_blacklist(unsigned long addr);
291extern int kprobe_add_ksym_blacklist(unsigned long entry);
292extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
293
294struct 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
305extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
306extern void __free_insn_slot(struct kprobe_insn_cache *c,
307			     kprobe_opcode_t *slot, int dirty);
308/* sleep-less address checking routine  */
309extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
310				unsigned long addr);
311
312#define DEFINE_INSN_CACHE_OPS(__name)					\
313extern struct kprobe_insn_cache kprobe_##__name##_slots;		\
314									\
315static inline kprobe_opcode_t *get_##__name##_slot(void)		\
316{									\
317	return __get_insn_slot(&kprobe_##__name##_slots);		\
318}									\
319									\
320static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
321{									\
322	__free_insn_slot(&kprobe_##__name##_slots, slot, dirty);	\
323}									\
324									\
325static 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"
331int 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)					\
335static inline bool is_kprobe_##__name##_slot(unsigned long addr)	\
336{									\
337	return 0;							\
338}
339#endif
340
341DEFINE_INSN_CACHE_OPS(insn);
342
343#ifdef CONFIG_OPTPROBES
344/*
345 * Internal structure for direct jump optimized probe
346 */
347struct 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 */
354extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
355extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
356extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
357					 struct kprobe *orig);
358extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
359extern void arch_optimize_kprobes(struct list_head *oplist);
360extern void arch_unoptimize_kprobes(struct list_head *oplist,
361				    struct list_head *done_list);
362extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
363extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
364					kprobe_opcode_t *addr);
365
366extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
367
368DEFINE_INSN_CACHE_OPS(optinsn);
369
370extern void wait_for_kprobe_optimizer(void);
371bool optprobe_queued_unopt(struct optimized_kprobe *op);
372bool kprobe_disarmed(struct kprobe *p);
373#else /* !CONFIG_OPTPROBES */
374static inline void wait_for_kprobe_optimizer(void) { }
375#endif /* CONFIG_OPTPROBES */
376
377#ifdef CONFIG_KPROBES_ON_FTRACE
378extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
379				  struct ftrace_ops *ops, struct ftrace_regs *fregs);
380extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
381#else
382static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
383{
384	return -EINVAL;
385}
386#endif /* CONFIG_KPROBES_ON_FTRACE */
387
388/* Get the kprobe at this addr (if any) - called with preemption disabled */
389struct kprobe *get_kprobe(void *addr);
390
391/* kprobe_running() will just return the current_kprobe on this CPU */
392static inline struct kprobe *kprobe_running(void)
393{
394	return __this_cpu_read(current_kprobe);
395}
396
397static inline void reset_current_kprobe(void)
398{
399	__this_cpu_write(current_kprobe, NULL);
400}
401
402static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
403{
404	return this_cpu_ptr(&kprobe_ctlblk);
405}
406
407kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
408kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry);
409
410int register_kprobe(struct kprobe *p);
411void unregister_kprobe(struct kprobe *p);
412int register_kprobes(struct kprobe **kps, int num);
413void unregister_kprobes(struct kprobe **kps, int num);
414
415int register_kretprobe(struct kretprobe *rp);
416void unregister_kretprobe(struct kretprobe *rp);
417int register_kretprobes(struct kretprobe **rps, int num);
418void unregister_kretprobes(struct kretprobe **rps, int num);
419
420#if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
421#define kprobe_flush_task(tk)	do {} while (0)
422#else
423void kprobe_flush_task(struct task_struct *tk);
424#endif
425
426void kprobe_free_init_mem(void);
427
428int disable_kprobe(struct kprobe *kp);
429int enable_kprobe(struct kprobe *kp);
430
431void dump_kprobe(struct kprobe *kp);
432
433void *alloc_insn_page(void);
434
435void *alloc_optinsn_page(void);
436void free_optinsn_page(void *page);
437
438int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
439		       char *sym);
440
441int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
442			    char *type, char *sym);
443
444int kprobe_exceptions_notify(struct notifier_block *self,
445			     unsigned long val, void *data);
446
447#else /* !CONFIG_KPROBES: */
448
449static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
450{
451	return 0;
452}
453static inline struct kprobe *get_kprobe(void *addr)
454{
455	return NULL;
456}
457static inline struct kprobe *kprobe_running(void)
458{
459	return NULL;
460}
461#define kprobe_busy_begin()	do {} while (0)
462#define kprobe_busy_end()	do {} while (0)
463
464static inline int register_kprobe(struct kprobe *p)
465{
466	return -EOPNOTSUPP;
467}
468static inline int register_kprobes(struct kprobe **kps, int num)
469{
470	return -EOPNOTSUPP;
471}
472static inline void unregister_kprobe(struct kprobe *p)
473{
474}
475static inline void unregister_kprobes(struct kprobe **kps, int num)
476{
477}
478static inline int register_kretprobe(struct kretprobe *rp)
479{
480	return -EOPNOTSUPP;
481}
482static inline int register_kretprobes(struct kretprobe **rps, int num)
483{
484	return -EOPNOTSUPP;
485}
486static inline void unregister_kretprobe(struct kretprobe *rp)
487{
488}
489static inline void unregister_kretprobes(struct kretprobe **rps, int num)
490{
491}
492static inline void kprobe_flush_task(struct task_struct *tk)
493{
494}
495static inline void kprobe_free_init_mem(void)
496{
497}
498static inline int disable_kprobe(struct kprobe *kp)
499{
500	return -EOPNOTSUPP;
501}
502static inline int enable_kprobe(struct kprobe *kp)
503{
504	return -EOPNOTSUPP;
505}
506
507static inline bool within_kprobe_blacklist(unsigned long addr)
508{
509	return true;
510}
511static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
512				     char *type, char *sym)
513{
514	return -ERANGE;
515}
516#endif /* CONFIG_KPROBES */
517
518static inline int disable_kretprobe(struct kretprobe *rp)
519{
520	return disable_kprobe(&rp->kp);
521}
522static inline int enable_kretprobe(struct kretprobe *rp)
523{
524	return enable_kprobe(&rp->kp);
525}
526
527#ifndef CONFIG_KPROBES
528static inline bool is_kprobe_insn_slot(unsigned long addr)
529{
530	return false;
531}
532#endif /* !CONFIG_KPROBES */
533
534#ifndef CONFIG_OPTPROBES
535static inline bool is_kprobe_optinsn_slot(unsigned long addr)
536{
537	return false;
538}
539#endif /* !CONFIG_OPTPROBES */
540
541#ifdef CONFIG_KRETPROBES
542#ifdef CONFIG_KRETPROBE_ON_RETHOOK
543static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
544{
545	return is_rethook_trampoline(addr);
546}
547
548static nokprobe_inline
549unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
550				      struct llist_node **cur)
551{
552	return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
553}
554#else
555static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
556{
557	return (void *)addr == kretprobe_trampoline_addr();
558}
559
560unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
561				      struct llist_node **cur);
562#endif
563#else
564static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
565{
566	return false;
567}
568
569static nokprobe_inline
570unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
571				      struct llist_node **cur)
572{
573	return 0;
574}
575#endif
576
577/* Returns true if kprobes handled the fault */
578static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
579					      unsigned int trap)
580{
581	if (!IS_ENABLED(CONFIG_KPROBES))
582		return false;
583	if (user_mode(regs))
584		return false;
585	/*
586	 * To be potentially processing a kprobe fault and to be allowed
587	 * to call kprobe_running(), we have to be non-preemptible.
588	 */
589	if (preemptible())
590		return false;
591	if (!kprobe_running())
592		return false;
593	return kprobe_fault_handler(regs, trap);
594}
595
596#endif /* _LINUX_KPROBES_H */
597