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 ? */
kprobe_gone(struct kprobe * p)114 static inline int kprobe_gone(struct kprobe *p)
115 {
116 	return p->flags & KPROBE_FLAG_GONE;
117 }
118 
119 /* Is this kprobe disabled ? */
kprobe_disabled(struct kprobe * p)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 ? */
kprobe_optimized(struct kprobe * p)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 ? */
kprobe_ftrace(struct kprobe * p)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  */
kprobes_built_in(void)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 */
arch_prepare_kretprobe(struct kretprobe * rp,struct pt_regs * regs)195 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
196 					struct pt_regs *regs)
197 {
198 }
arch_trampoline_kprobe(struct kprobe * p)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 
kretprobe_assert(struct kretprobe_instance * ri,unsigned long orig_ret_address,unsigned long trampoline_address)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
init_test_probes(void)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
wait_for_kprobe_optimizer(void)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 */
kprobe_running(void)338 static inline struct kprobe *kprobe_running(void)
339 {
340 	return (__this_cpu_read(current_kprobe));
341 }
342 
reset_current_kprobe(void)343 static inline void reset_current_kprobe(void)
344 {
345 	__this_cpu_write(current_kprobe, NULL);
346 }
347 
get_kprobe_ctlblk(void)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 
kprobes_built_in(void)378 static inline int kprobes_built_in(void)
379 {
380 	return 0;
381 }
kprobe_fault_handler(struct pt_regs * regs,int trapnr)382 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
383 {
384 	return 0;
385 }
get_kprobe(void * addr)386 static inline struct kprobe *get_kprobe(void *addr)
387 {
388 	return NULL;
389 }
kprobe_running(void)390 static inline struct kprobe *kprobe_running(void)
391 {
392 	return NULL;
393 }
register_kprobe(struct kprobe * p)394 static inline int register_kprobe(struct kprobe *p)
395 {
396 	return -ENOSYS;
397 }
register_kprobes(struct kprobe ** kps,int num)398 static inline int register_kprobes(struct kprobe **kps, int num)
399 {
400 	return -ENOSYS;
401 }
unregister_kprobe(struct kprobe * p)402 static inline void unregister_kprobe(struct kprobe *p)
403 {
404 }
unregister_kprobes(struct kprobe ** kps,int num)405 static inline void unregister_kprobes(struct kprobe **kps, int num)
406 {
407 }
register_kretprobe(struct kretprobe * rp)408 static inline int register_kretprobe(struct kretprobe *rp)
409 {
410 	return -ENOSYS;
411 }
register_kretprobes(struct kretprobe ** rps,int num)412 static inline int register_kretprobes(struct kretprobe **rps, int num)
413 {
414 	return -ENOSYS;
415 }
unregister_kretprobe(struct kretprobe * rp)416 static inline void unregister_kretprobe(struct kretprobe *rp)
417 {
418 }
unregister_kretprobes(struct kretprobe ** rps,int num)419 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
420 {
421 }
kprobe_flush_task(struct task_struct * tk)422 static inline void kprobe_flush_task(struct task_struct *tk)
423 {
424 }
disable_kprobe(struct kprobe * kp)425 static inline int disable_kprobe(struct kprobe *kp)
426 {
427 	return -ENOSYS;
428 }
enable_kprobe(struct kprobe * kp)429 static inline int enable_kprobe(struct kprobe *kp)
430 {
431 	return -ENOSYS;
432 }
433 
within_kprobe_blacklist(unsigned long addr)434 static inline bool within_kprobe_blacklist(unsigned long addr)
435 {
436 	return true;
437 }
438 #endif /* CONFIG_KPROBES */
disable_kretprobe(struct kretprobe * rp)439 static inline int disable_kretprobe(struct kretprobe *rp)
440 {
441 	return disable_kprobe(&rp->kp);
442 }
enable_kretprobe(struct kretprobe * rp)443 static inline int enable_kretprobe(struct kretprobe *rp)
444 {
445 	return enable_kprobe(&rp->kp);
446 }
447 
448 #ifndef CONFIG_KPROBES
is_kprobe_insn_slot(unsigned long addr)449 static inline bool is_kprobe_insn_slot(unsigned long addr)
450 {
451 	return false;
452 }
453 #endif
454 #ifndef CONFIG_OPTPROBES
is_kprobe_optinsn_slot(unsigned long addr)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 */
kprobe_page_fault(struct pt_regs * regs,unsigned int trap)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 */
481