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 #include <linux/seqlock.h>
20
21 struct uprobe;
22 struct vm_area_struct;
23 struct mm_struct;
24 struct inode;
25 struct notifier_block;
26 struct page;
27
28 /*
29 * Allowed return values from uprobe consumer's handler callback
30 * with following meaning:
31 *
32 * UPROBE_HANDLER_REMOVE
33 * - Remove the uprobe breakpoint from current->mm.
34 * UPROBE_HANDLER_IGNORE
35 * - Ignore ret_handler callback for this consumer.
36 */
37 #define UPROBE_HANDLER_REMOVE 1
38 #define UPROBE_HANDLER_IGNORE 2
39
40 #define MAX_URETPROBE_DEPTH 64
41
42 #define UPROBE_NO_TRAMPOLINE_VADDR (~0UL)
43
44 struct uprobe_consumer {
45 /*
46 * handler() can return UPROBE_HANDLER_REMOVE to signal the need to
47 * unregister uprobe for current process. If UPROBE_HANDLER_REMOVE is
48 * returned, filter() callback has to be implemented as well and it
49 * should return false to "confirm" the decision to uninstall uprobe
50 * for the current process. If filter() is omitted or returns true,
51 * UPROBE_HANDLER_REMOVE is effectively ignored.
52 */
53 int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs, __u64 *data);
54 int (*ret_handler)(struct uprobe_consumer *self,
55 unsigned long func,
56 struct pt_regs *regs, __u64 *data);
57 bool (*filter)(struct uprobe_consumer *self, struct mm_struct *mm);
58
59 struct list_head cons_node;
60
61 __u64 id; /* set when uprobe_consumer is registered */
62 };
63
64 #ifdef CONFIG_UPROBES
65 #include <asm/uprobes.h>
66
67 enum uprobe_task_state {
68 UTASK_RUNNING,
69 UTASK_SSTEP,
70 UTASK_SSTEP_ACK,
71 UTASK_SSTEP_TRAPPED,
72 };
73
74 /* The state of hybrid-lifetime uprobe inside struct return_instance */
75 enum hprobe_state {
76 HPROBE_LEASED, /* uretprobes_srcu-protected uprobe */
77 HPROBE_STABLE, /* refcounted uprobe */
78 HPROBE_GONE, /* NULL uprobe, SRCU expired, refcount failed */
79 HPROBE_CONSUMED, /* uprobe "consumed" by uretprobe handler */
80 };
81
82 /*
83 * Hybrid lifetime uprobe. Represents a uprobe instance that could be either
84 * SRCU protected (with SRCU protection eventually potentially timing out),
85 * refcounted using uprobe->ref, or there could be no valid uprobe (NULL).
86 *
87 * hprobe's internal state is setup such that background timer thread can
88 * atomically "downgrade" temporarily RCU-protected uprobe into refcounted one
89 * (or no uprobe, if refcounting failed).
90 *
91 * *stable* pointer always point to the uprobe (or could be NULL if there is
92 * was no valid underlying uprobe to begin with).
93 *
94 * *leased* pointer is the key to achieving race-free atomic lifetime state
95 * transition and can have three possible states:
96 * - either the same non-NULL value as *stable*, in which case uprobe is
97 * SRCU-protected;
98 * - NULL, in which case uprobe (if there is any) is refcounted;
99 * - special __UPROBE_DEAD value, which represents an uprobe that was SRCU
100 * protected initially, but SRCU period timed out and we attempted to
101 * convert it to refcounted, but refcount_inc_not_zero() failed, because
102 * uprobe effectively went away (the last consumer unsubscribed). In this
103 * case it's important to know that *stable* pointer (which still has
104 * non-NULL uprobe pointer) shouldn't be used, because lifetime of
105 * underlying uprobe is not guaranteed anymore. __UPROBE_DEAD is just an
106 * internal marker and is handled transparently by hprobe_fetch() helper.
107 *
108 * When uprobe is SRCU-protected, we also record srcu_idx value, necessary for
109 * SRCU unlocking.
110 *
111 * See hprobe_expire() and hprobe_fetch() for details of race-free uprobe
112 * state transitioning details. It all hinges on atomic xchg() over *leaded*
113 * pointer. *stable* pointer, once initially set, is not modified concurrently.
114 */
115 struct hprobe {
116 enum hprobe_state state;
117 int srcu_idx;
118 struct uprobe *uprobe;
119 };
120
121 /*
122 * uprobe_task: Metadata of a task while it singlesteps.
123 */
124 struct uprobe_task {
125 enum uprobe_task_state state;
126
127 unsigned int depth;
128 struct return_instance *return_instances;
129
130 struct return_instance *ri_pool;
131 struct timer_list ri_timer;
132 seqcount_t ri_seqcount;
133
134 union {
135 struct {
136 struct arch_uprobe_task autask;
137 unsigned long vaddr;
138 };
139
140 struct {
141 struct callback_head dup_xol_work;
142 unsigned long dup_xol_addr;
143 };
144 };
145
146 struct uprobe *active_uprobe;
147 unsigned long xol_vaddr;
148 bool signal_denied;
149
150 struct arch_uprobe *auprobe;
151 };
152
153 struct return_consumer {
154 __u64 cookie;
155 __u64 id;
156 };
157
158 struct return_instance {
159 struct hprobe hprobe;
160 unsigned long func;
161 unsigned long stack; /* stack pointer */
162 unsigned long orig_ret_vaddr; /* original return address */
163 bool chained; /* true, if instance is nested */
164 int cons_cnt; /* total number of session consumers */
165
166 struct return_instance *next; /* keep as stack */
167 struct rcu_head rcu;
168
169 /* singular pre-allocated return_consumer instance for common case */
170 struct return_consumer consumer;
171 /*
172 * extra return_consumer instances for rare cases of multiple session consumers,
173 * contains (cons_cnt - 1) elements
174 */
175 struct return_consumer *extra_consumers;
176 } ____cacheline_aligned;
177
178 enum rp_check {
179 RP_CHECK_CALL,
180 RP_CHECK_CHAIN_CALL,
181 RP_CHECK_RET,
182 };
183
184 struct xol_area;
185
186 struct uprobes_state {
187 struct xol_area *xol_area;
188 };
189
190 extern void __init uprobes_init(void);
191 extern int set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
192 extern int set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
193 extern bool is_swbp_insn(uprobe_opcode_t *insn);
194 extern bool is_trap_insn(uprobe_opcode_t *insn);
195 extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
196 extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
197 extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t);
198 extern struct uprobe *uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
199 extern int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool);
200 extern void uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc);
201 extern void uprobe_unregister_sync(void);
202 extern int uprobe_mmap(struct vm_area_struct *vma);
203 extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end);
204 extern void uprobe_start_dup_mmap(void);
205 extern void uprobe_end_dup_mmap(void);
206 extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm);
207 extern void uprobe_free_utask(struct task_struct *t);
208 extern void uprobe_copy_process(struct task_struct *t, unsigned long flags);
209 extern int uprobe_post_sstep_notifier(struct pt_regs *regs);
210 extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
211 extern void uprobe_notify_resume(struct pt_regs *regs);
212 extern bool uprobe_deny_signal(void);
213 extern bool arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs);
214 extern void uprobe_clear_state(struct mm_struct *mm);
215 extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
216 extern int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
217 extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
218 extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
219 extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
220 extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
221 extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
222 extern bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, struct pt_regs *regs);
223 extern bool arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
224 extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
225 void *src, unsigned long len);
226 extern void uprobe_handle_trampoline(struct pt_regs *regs);
227 extern void *arch_uprobe_trampoline(unsigned long *psize);
228 extern unsigned long uprobe_get_trampoline_vaddr(void);
229 #else /* !CONFIG_UPROBES */
230 struct uprobes_state {
231 };
232
uprobes_init(void)233 static inline void uprobes_init(void)
234 {
235 }
236
237 #define uprobe_get_trap_addr(regs) instruction_pointer(regs)
238
239 static inline struct uprobe *
uprobe_register(struct inode * inode,loff_t offset,loff_t ref_ctr_offset,struct uprobe_consumer * uc)240 uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc)
241 {
242 return ERR_PTR(-ENOSYS);
243 }
244 static inline int
uprobe_apply(struct uprobe * uprobe,struct uprobe_consumer * uc,bool add)245 uprobe_apply(struct uprobe* uprobe, struct uprobe_consumer *uc, bool add)
246 {
247 return -ENOSYS;
248 }
249 static inline void
uprobe_unregister_nosync(struct uprobe * uprobe,struct uprobe_consumer * uc)250 uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc)
251 {
252 }
uprobe_unregister_sync(void)253 static inline void uprobe_unregister_sync(void)
254 {
255 }
uprobe_mmap(struct vm_area_struct * vma)256 static inline int uprobe_mmap(struct vm_area_struct *vma)
257 {
258 return 0;
259 }
260 static inline void
uprobe_munmap(struct vm_area_struct * vma,unsigned long start,unsigned long end)261 uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
262 {
263 }
uprobe_start_dup_mmap(void)264 static inline void uprobe_start_dup_mmap(void)
265 {
266 }
uprobe_end_dup_mmap(void)267 static inline void uprobe_end_dup_mmap(void)
268 {
269 }
270 static inline void
uprobe_dup_mmap(struct mm_struct * oldmm,struct mm_struct * newmm)271 uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
272 {
273 }
uprobe_notify_resume(struct pt_regs * regs)274 static inline void uprobe_notify_resume(struct pt_regs *regs)
275 {
276 }
uprobe_deny_signal(void)277 static inline bool uprobe_deny_signal(void)
278 {
279 return false;
280 }
uprobe_free_utask(struct task_struct * t)281 static inline void uprobe_free_utask(struct task_struct *t)
282 {
283 }
uprobe_copy_process(struct task_struct * t,unsigned long flags)284 static inline void uprobe_copy_process(struct task_struct *t, unsigned long flags)
285 {
286 }
uprobe_clear_state(struct mm_struct * mm)287 static inline void uprobe_clear_state(struct mm_struct *mm)
288 {
289 }
290 #endif /* !CONFIG_UPROBES */
291 #endif /* _LINUX_UPROBES_H */
292