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 *
  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
272extern int arch_prepare_kprobe(struct kprobe *p);
273extern void arch_arm_kprobe(struct kprobe *p);
274extern void arch_disarm_kprobe(struct kprobe *p);
275extern int arch_init_kprobes(void);
276extern void kprobes_inc_nmissed_count(struct kprobe *p);
277extern bool arch_within_kprobe_blacklist(unsigned long addr);
278extern int arch_populate_kprobe_blacklist(void);
279extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
280
281extern bool within_kprobe_blacklist(unsigned long addr);
282extern int kprobe_add_ksym_blacklist(unsigned long entry);
283extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
284
285struct kprobe_insn_cache {
286	struct mutex mutex;
287	void *(*alloc)(void);	/* allocate insn page */
288	void (*free)(void *);	/* free insn page */
289	const char *sym;	/* symbol for insn pages */
290	struct list_head pages; /* list of kprobe_insn_page */
291	size_t insn_size;	/* size of instruction slot */
292	int nr_garbage;
293};
294
295#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
296extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
297extern void __free_insn_slot(struct kprobe_insn_cache *c,
298			     kprobe_opcode_t *slot, int dirty);
299/* sleep-less address checking routine  */
300extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
301				unsigned long addr);
302
303#define DEFINE_INSN_CACHE_OPS(__name)					\
304extern struct kprobe_insn_cache kprobe_##__name##_slots;		\
305									\
306static inline kprobe_opcode_t *get_##__name##_slot(void)		\
307{									\
308	return __get_insn_slot(&kprobe_##__name##_slots);		\
309}									\
310									\
311static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
312{									\
313	__free_insn_slot(&kprobe_##__name##_slots, slot, dirty);	\
314}									\
315									\
316static inline bool is_kprobe_##__name##_slot(unsigned long addr)	\
317{									\
318	return __is_insn_slot_addr(&kprobe_##__name##_slots, addr);	\
319}
320#define KPROBE_INSN_PAGE_SYM		"kprobe_insn_page"
321#define KPROBE_OPTINSN_PAGE_SYM		"kprobe_optinsn_page"
322int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
323			     unsigned long *value, char *type, char *sym);
324#else /* !__ARCH_WANT_KPROBES_INSN_SLOT */
325#define DEFINE_INSN_CACHE_OPS(__name)					\
326static inline bool is_kprobe_##__name##_slot(unsigned long addr)	\
327{									\
328	return 0;							\
329}
330#endif
331
332DEFINE_INSN_CACHE_OPS(insn);
333
334#ifdef CONFIG_OPTPROBES
335/*
336 * Internal structure for direct jump optimized probe
337 */
338struct optimized_kprobe {
339	struct kprobe kp;
340	struct list_head list;	/* list for optimizing queue */
341	struct arch_optimized_insn optinsn;
342};
343
344/* Architecture dependent functions for direct jump optimization */
345extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
346extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
347extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
348					 struct kprobe *orig);
349extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
350extern void arch_optimize_kprobes(struct list_head *oplist);
351extern void arch_unoptimize_kprobes(struct list_head *oplist,
352				    struct list_head *done_list);
353extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
354extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
355					kprobe_opcode_t *addr);
356
357extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
358
359DEFINE_INSN_CACHE_OPS(optinsn);
360
361extern void wait_for_kprobe_optimizer(void);
362bool optprobe_queued_unopt(struct optimized_kprobe *op);
363bool kprobe_disarmed(struct kprobe *p);
364#else /* !CONFIG_OPTPROBES */
365static inline void wait_for_kprobe_optimizer(void) { }
366#endif /* CONFIG_OPTPROBES */
367
368#ifdef CONFIG_KPROBES_ON_FTRACE
369extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
370				  struct ftrace_ops *ops, struct ftrace_regs *fregs);
371extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
372/* Set when ftrace has been killed: kprobes on ftrace must be disabled for safety */
373extern bool kprobe_ftrace_disabled __read_mostly;
374extern void kprobe_ftrace_kill(void);
375#else
376static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
377{
378	return -EINVAL;
379}
380static inline void kprobe_ftrace_kill(void) {}
381#endif /* CONFIG_KPROBES_ON_FTRACE */
382
383/* Get the kprobe at this addr (if any) - called with preemption disabled */
384struct kprobe *get_kprobe(void *addr);
385
386/* kprobe_running() will just return the current_kprobe on this CPU */
387static inline struct kprobe *kprobe_running(void)
388{
389	return __this_cpu_read(current_kprobe);
390}
391
392static inline void reset_current_kprobe(void)
393{
394	__this_cpu_write(current_kprobe, NULL);
395}
396
397static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
398{
399	return this_cpu_ptr(&kprobe_ctlblk);
400}
401
402kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
403kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry);
404
405int register_kprobe(struct kprobe *p);
406void unregister_kprobe(struct kprobe *p);
407int register_kprobes(struct kprobe **kps, int num);
408void unregister_kprobes(struct kprobe **kps, int num);
409
410int register_kretprobe(struct kretprobe *rp);
411void unregister_kretprobe(struct kretprobe *rp);
412int register_kretprobes(struct kretprobe **rps, int num);
413void unregister_kretprobes(struct kretprobe **rps, int num);
414
415#if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
416#define kprobe_flush_task(tk)	do {} while (0)
417#else
418void kprobe_flush_task(struct task_struct *tk);
419#endif
420
421void kprobe_free_init_mem(void);
422
423int disable_kprobe(struct kprobe *kp);
424int enable_kprobe(struct kprobe *kp);
425
426void dump_kprobe(struct kprobe *kp);
427
428void *alloc_insn_page(void);
429
430void *alloc_optinsn_page(void);
431void free_optinsn_page(void *page);
432
433int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
434		       char *sym);
435
436int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
437			    char *type, char *sym);
438
439int kprobe_exceptions_notify(struct notifier_block *self,
440			     unsigned long val, void *data);
441
442#else /* !CONFIG_KPROBES: */
443
444static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
445{
446	return 0;
447}
448static inline struct kprobe *get_kprobe(void *addr)
449{
450	return NULL;
451}
452static inline struct kprobe *kprobe_running(void)
453{
454	return NULL;
455}
456#define kprobe_busy_begin()	do {} while (0)
457#define kprobe_busy_end()	do {} while (0)
458
459static inline int register_kprobe(struct kprobe *p)
460{
461	return -EOPNOTSUPP;
462}
463static inline int register_kprobes(struct kprobe **kps, int num)
464{
465	return -EOPNOTSUPP;
466}
467static inline void unregister_kprobe(struct kprobe *p)
468{
469}
470static inline void unregister_kprobes(struct kprobe **kps, int num)
471{
472}
473static inline int register_kretprobe(struct kretprobe *rp)
474{
475	return -EOPNOTSUPP;
476}
477static inline int register_kretprobes(struct kretprobe **rps, int num)
478{
479	return -EOPNOTSUPP;
480}
481static inline void unregister_kretprobe(struct kretprobe *rp)
482{
483}
484static inline void unregister_kretprobes(struct kretprobe **rps, int num)
485{
486}
487static inline void kprobe_flush_task(struct task_struct *tk)
488{
489}
490static inline void kprobe_free_init_mem(void)
491{
492}
493static inline void kprobe_ftrace_kill(void)
494{
495}
496static inline int disable_kprobe(struct kprobe *kp)
497{
498	return -EOPNOTSUPP;
499}
500static inline int enable_kprobe(struct kprobe *kp)
501{
502	return -EOPNOTSUPP;
503}
504
505static inline bool within_kprobe_blacklist(unsigned long addr)
506{
507	return true;
508}
509static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
510				     char *type, char *sym)
511{
512	return -ERANGE;
513}
514#endif /* CONFIG_KPROBES */
515
516static inline int disable_kretprobe(struct kretprobe *rp)
517{
518	return disable_kprobe(&rp->kp);
519}
520static inline int enable_kretprobe(struct kretprobe *rp)
521{
522	return enable_kprobe(&rp->kp);
523}
524
525#ifndef CONFIG_KPROBES
526static inline bool is_kprobe_insn_slot(unsigned long addr)
527{
528	return false;
529}
530#endif /* !CONFIG_KPROBES */
531
532#ifndef CONFIG_OPTPROBES
533static inline bool is_kprobe_optinsn_slot(unsigned long addr)
534{
535	return false;
536}
537#endif /* !CONFIG_OPTPROBES */
538
539#ifdef CONFIG_KRETPROBES
540#ifdef CONFIG_KRETPROBE_ON_RETHOOK
541static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
542{
543	return is_rethook_trampoline(addr);
544}
545
546static nokprobe_inline
547unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
548				      struct llist_node **cur)
549{
550	return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
551}
552#else
553static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
554{
555	return (void *)addr == kretprobe_trampoline_addr();
556}
557
558unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
559				      struct llist_node **cur);
560#endif
561#else
562static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
563{
564	return false;
565}
566
567static nokprobe_inline
568unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
569				      struct llist_node **cur)
570{
571	return 0;
572}
573#endif
574
575/* Returns true if kprobes handled the fault */
576static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
577					      unsigned int trap)
578{
579	if (!IS_ENABLED(CONFIG_KPROBES))
580		return false;
581	if (user_mode(regs))
582		return false;
583	/*
584	 * To be potentially processing a kprobe fault and to be allowed
585	 * to call kprobe_running(), we have to be non-preemptible.
586	 */
587	if (preemptible())
588		return false;
589	if (!kprobe_running())
590		return false;
591	return kprobe_fault_handler(regs, trap);
592}
593
594#endif /* _LINUX_KPROBES_H */