xref: /linux/include/linux/uprobes.h (revision 3fd6c59042dbba50391e30862beac979491145fe)
1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 #ifndef _LINUX_UPROBES_H
3 #define _LINUX_UPROBES_H
4 /*
5  * User-space Probes (UProbes)
6  *
7  * Copyright (C) IBM Corporation, 2008-2012
8  * Authors:
9  *	Srikar Dronamraju
10  *	Jim Keniston
11  * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra
12  */
13 
14 #include <linux/errno.h>
15 #include <linux/rbtree.h>
16 #include <linux/types.h>
17 #include <linux/wait.h>
18 #include <linux/timer.h>
19 
20 struct uprobe;
21 struct vm_area_struct;
22 struct mm_struct;
23 struct inode;
24 struct notifier_block;
25 struct page;
26 
27 /*
28  * Allowed return values from uprobe consumer's handler callback
29  * with following meaning:
30  *
31  * UPROBE_HANDLER_REMOVE
32  * - Remove the uprobe breakpoint from current->mm.
33  * UPROBE_HANDLER_IGNORE
34  * - Ignore ret_handler callback for this consumer.
35  */
36 #define UPROBE_HANDLER_REMOVE		1
37 #define UPROBE_HANDLER_IGNORE		2
38 
39 #define MAX_URETPROBE_DEPTH		64
40 
41 struct uprobe_consumer {
42 	/*
43 	 * handler() can return UPROBE_HANDLER_REMOVE to signal the need to
44 	 * unregister uprobe for current process. If UPROBE_HANDLER_REMOVE is
45 	 * returned, filter() callback has to be implemented as well and it
46 	 * should return false to "confirm" the decision to uninstall uprobe
47 	 * for the current process. If filter() is omitted or returns true,
48 	 * UPROBE_HANDLER_REMOVE is effectively ignored.
49 	 */
50 	int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs, __u64 *data);
51 	int (*ret_handler)(struct uprobe_consumer *self,
52 				unsigned long func,
53 				struct pt_regs *regs, __u64 *data);
54 	bool (*filter)(struct uprobe_consumer *self, struct mm_struct *mm);
55 
56 	struct list_head cons_node;
57 
58 	__u64 id;	/* set when uprobe_consumer is registered */
59 };
60 
61 #ifdef CONFIG_UPROBES
62 #include <asm/uprobes.h>
63 
64 enum uprobe_task_state {
65 	UTASK_RUNNING,
66 	UTASK_SSTEP,
67 	UTASK_SSTEP_ACK,
68 	UTASK_SSTEP_TRAPPED,
69 };
70 
71 /* The state of hybrid-lifetime uprobe inside struct return_instance */
72 enum hprobe_state {
73 	HPROBE_LEASED,		/* uretprobes_srcu-protected uprobe */
74 	HPROBE_STABLE,		/* refcounted uprobe */
75 	HPROBE_GONE,		/* NULL uprobe, SRCU expired, refcount failed */
76 	HPROBE_CONSUMED,	/* uprobe "consumed" by uretprobe handler */
77 };
78 
79 /*
80  * Hybrid lifetime uprobe. Represents a uprobe instance that could be either
81  * SRCU protected (with SRCU protection eventually potentially timing out),
82  * refcounted using uprobe->ref, or there could be no valid uprobe (NULL).
83  *
84  * hprobe's internal state is setup such that background timer thread can
85  * atomically "downgrade" temporarily RCU-protected uprobe into refcounted one
86  * (or no uprobe, if refcounting failed).
87  *
88  * *stable* pointer always point to the uprobe (or could be NULL if there is
89  * was no valid underlying uprobe to begin with).
90  *
91  * *leased* pointer is the key to achieving race-free atomic lifetime state
92  * transition and can have three possible states:
93  *   - either the same non-NULL value as *stable*, in which case uprobe is
94  *     SRCU-protected;
95  *   - NULL, in which case uprobe (if there is any) is refcounted;
96  *   - special __UPROBE_DEAD value, which represents an uprobe that was SRCU
97  *     protected initially, but SRCU period timed out and we attempted to
98  *     convert it to refcounted, but refcount_inc_not_zero() failed, because
99  *     uprobe effectively went away (the last consumer unsubscribed). In this
100  *     case it's important to know that *stable* pointer (which still has
101  *     non-NULL uprobe pointer) shouldn't be used, because lifetime of
102  *     underlying uprobe is not guaranteed anymore. __UPROBE_DEAD is just an
103  *     internal marker and is handled transparently by hprobe_fetch() helper.
104  *
105  * When uprobe is SRCU-protected, we also record srcu_idx value, necessary for
106  * SRCU unlocking.
107  *
108  * See hprobe_expire() and hprobe_fetch() for details of race-free uprobe
109  * state transitioning details. It all hinges on atomic xchg() over *leaded*
110  * pointer. *stable* pointer, once initially set, is not modified concurrently.
111  */
112 struct hprobe {
113 	enum hprobe_state state;
114 	int srcu_idx;
115 	struct uprobe *uprobe;
116 };
117 
118 /*
119  * uprobe_task: Metadata of a task while it singlesteps.
120  */
121 struct uprobe_task {
122 	enum uprobe_task_state		state;
123 
124 	unsigned int			depth;
125 	struct return_instance		*return_instances;
126 
127 	union {
128 		struct {
129 			struct arch_uprobe_task	autask;
130 			unsigned long		vaddr;
131 		};
132 
133 		struct {
134 			struct callback_head	dup_xol_work;
135 			unsigned long		dup_xol_addr;
136 		};
137 	};
138 
139 	struct uprobe			*active_uprobe;
140 	struct timer_list		ri_timer;
141 	unsigned long			xol_vaddr;
142 
143 	struct arch_uprobe              *auprobe;
144 };
145 
146 struct return_consumer {
147 	__u64	cookie;
148 	__u64	id;
149 };
150 
151 struct return_instance {
152 	struct hprobe		hprobe;
153 	unsigned long		func;
154 	unsigned long		stack;		/* stack pointer */
155 	unsigned long		orig_ret_vaddr; /* original return address */
156 	bool			chained;	/* true, if instance is nested */
157 	int			consumers_cnt;
158 
159 	struct return_instance	*next;		/* keep as stack */
160 	struct rcu_head		rcu;
161 
162 	struct return_consumer	consumers[] __counted_by(consumers_cnt);
163 } ____cacheline_aligned;
164 
165 enum rp_check {
166 	RP_CHECK_CALL,
167 	RP_CHECK_CHAIN_CALL,
168 	RP_CHECK_RET,
169 };
170 
171 struct xol_area;
172 
173 struct uprobes_state {
174 	struct xol_area		*xol_area;
175 };
176 
177 extern void __init uprobes_init(void);
178 extern int set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
179 extern int set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
180 extern bool is_swbp_insn(uprobe_opcode_t *insn);
181 extern bool is_trap_insn(uprobe_opcode_t *insn);
182 extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
183 extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
184 extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t);
185 extern struct uprobe *uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
186 extern int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool);
187 extern void uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc);
188 extern void uprobe_unregister_sync(void);
189 extern int uprobe_mmap(struct vm_area_struct *vma);
190 extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end);
191 extern void uprobe_start_dup_mmap(void);
192 extern void uprobe_end_dup_mmap(void);
193 extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm);
194 extern void uprobe_free_utask(struct task_struct *t);
195 extern void uprobe_copy_process(struct task_struct *t, unsigned long flags);
196 extern int uprobe_post_sstep_notifier(struct pt_regs *regs);
197 extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
198 extern void uprobe_notify_resume(struct pt_regs *regs);
199 extern bool uprobe_deny_signal(void);
200 extern bool arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs);
201 extern void uprobe_clear_state(struct mm_struct *mm);
202 extern int  arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
203 extern int  arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
204 extern int  arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
205 extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
206 extern int  arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
207 extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
208 extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
209 extern bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, struct pt_regs *regs);
210 extern bool arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
211 extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
212 					 void *src, unsigned long len);
213 extern void uprobe_handle_trampoline(struct pt_regs *regs);
214 extern void *arch_uprobe_trampoline(unsigned long *psize);
215 extern unsigned long uprobe_get_trampoline_vaddr(void);
216 #else /* !CONFIG_UPROBES */
217 struct uprobes_state {
218 };
219 
uprobes_init(void)220 static inline void uprobes_init(void)
221 {
222 }
223 
224 #define uprobe_get_trap_addr(regs)	instruction_pointer(regs)
225 
226 static inline struct uprobe *
uprobe_register(struct inode * inode,loff_t offset,loff_t ref_ctr_offset,struct uprobe_consumer * uc)227 uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc)
228 {
229 	return ERR_PTR(-ENOSYS);
230 }
231 static inline int
uprobe_apply(struct uprobe * uprobe,struct uprobe_consumer * uc,bool add)232 uprobe_apply(struct uprobe* uprobe, struct uprobe_consumer *uc, bool add)
233 {
234 	return -ENOSYS;
235 }
236 static inline void
uprobe_unregister_nosync(struct uprobe * uprobe,struct uprobe_consumer * uc)237 uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc)
238 {
239 }
uprobe_unregister_sync(void)240 static inline void uprobe_unregister_sync(void)
241 {
242 }
uprobe_mmap(struct vm_area_struct * vma)243 static inline int uprobe_mmap(struct vm_area_struct *vma)
244 {
245 	return 0;
246 }
247 static inline void
uprobe_munmap(struct vm_area_struct * vma,unsigned long start,unsigned long end)248 uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
249 {
250 }
uprobe_start_dup_mmap(void)251 static inline void uprobe_start_dup_mmap(void)
252 {
253 }
uprobe_end_dup_mmap(void)254 static inline void uprobe_end_dup_mmap(void)
255 {
256 }
257 static inline void
uprobe_dup_mmap(struct mm_struct * oldmm,struct mm_struct * newmm)258 uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
259 {
260 }
uprobe_notify_resume(struct pt_regs * regs)261 static inline void uprobe_notify_resume(struct pt_regs *regs)
262 {
263 }
uprobe_deny_signal(void)264 static inline bool uprobe_deny_signal(void)
265 {
266 	return false;
267 }
uprobe_free_utask(struct task_struct * t)268 static inline void uprobe_free_utask(struct task_struct *t)
269 {
270 }
uprobe_copy_process(struct task_struct * t,unsigned long flags)271 static inline void uprobe_copy_process(struct task_struct *t, unsigned long flags)
272 {
273 }
uprobe_clear_state(struct mm_struct * mm)274 static inline void uprobe_clear_state(struct mm_struct *mm)
275 {
276 }
277 #endif /* !CONFIG_UPROBES */
278 #endif	/* _LINUX_UPROBES_H */
279