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 #include <linux/mutex.h>
21
22 struct uprobe;
23 struct vm_area_struct;
24 struct mm_struct;
25 struct inode;
26 struct notifier_block;
27 struct page;
28
29 /*
30 * Allowed return values from uprobe consumer's handler callback
31 * with following meaning:
32 *
33 * UPROBE_HANDLER_REMOVE
34 * - Remove the uprobe breakpoint from current->mm.
35 * UPROBE_HANDLER_IGNORE
36 * - Ignore ret_handler callback for this consumer.
37 */
38 #define UPROBE_HANDLER_REMOVE 1
39 #define UPROBE_HANDLER_IGNORE 2
40
41 #define MAX_URETPROBE_DEPTH 64
42
43 #define UPROBE_NO_TRAMPOLINE_VADDR (~0UL)
44
45 struct uprobe_consumer {
46 /*
47 * handler() can return UPROBE_HANDLER_REMOVE to signal the need to
48 * unregister uprobe for current process. If UPROBE_HANDLER_REMOVE is
49 * returned, filter() callback has to be implemented as well and it
50 * should return false to "confirm" the decision to uninstall uprobe
51 * for the current process. If filter() is omitted or returns true,
52 * UPROBE_HANDLER_REMOVE is effectively ignored.
53 */
54 int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs, __u64 *data);
55 int (*ret_handler)(struct uprobe_consumer *self,
56 unsigned long func,
57 struct pt_regs *regs, __u64 *data);
58 bool (*filter)(struct uprobe_consumer *self, struct mm_struct *mm);
59
60 struct list_head cons_node;
61
62 __u64 id; /* set when uprobe_consumer is registered */
63 };
64
65 #ifdef CONFIG_UPROBES
66 #include <asm/uprobes.h>
67
68 enum uprobe_task_state {
69 UTASK_RUNNING,
70 UTASK_SSTEP,
71 UTASK_SSTEP_ACK,
72 UTASK_SSTEP_TRAPPED,
73 };
74
75 /* The state of hybrid-lifetime uprobe inside struct return_instance */
76 enum hprobe_state {
77 HPROBE_LEASED, /* uretprobes_srcu-protected uprobe */
78 HPROBE_STABLE, /* refcounted uprobe */
79 HPROBE_GONE, /* NULL uprobe, SRCU expired, refcount failed */
80 HPROBE_CONSUMED, /* uprobe "consumed" by uretprobe handler */
81 };
82
83 /*
84 * Hybrid lifetime uprobe. Represents a uprobe instance that could be either
85 * SRCU protected (with SRCU protection eventually potentially timing out),
86 * refcounted using uprobe->ref, or there could be no valid uprobe (NULL).
87 *
88 * hprobe's internal state is setup such that background timer thread can
89 * atomically "downgrade" temporarily RCU-protected uprobe into refcounted one
90 * (or no uprobe, if refcounting failed).
91 *
92 * *stable* pointer always point to the uprobe (or could be NULL if there is
93 * was no valid underlying uprobe to begin with).
94 *
95 * *leased* pointer is the key to achieving race-free atomic lifetime state
96 * transition and can have three possible states:
97 * - either the same non-NULL value as *stable*, in which case uprobe is
98 * SRCU-protected;
99 * - NULL, in which case uprobe (if there is any) is refcounted;
100 * - special __UPROBE_DEAD value, which represents an uprobe that was SRCU
101 * protected initially, but SRCU period timed out and we attempted to
102 * convert it to refcounted, but refcount_inc_not_zero() failed, because
103 * uprobe effectively went away (the last consumer unsubscribed). In this
104 * case it's important to know that *stable* pointer (which still has
105 * non-NULL uprobe pointer) shouldn't be used, because lifetime of
106 * underlying uprobe is not guaranteed anymore. __UPROBE_DEAD is just an
107 * internal marker and is handled transparently by hprobe_fetch() helper.
108 *
109 * When uprobe is SRCU-protected, we also record srcu_idx value, necessary for
110 * SRCU unlocking.
111 *
112 * See hprobe_expire() and hprobe_fetch() for details of race-free uprobe
113 * state transitioning details. It all hinges on atomic xchg() over *leaded*
114 * pointer. *stable* pointer, once initially set, is not modified concurrently.
115 */
116 struct hprobe {
117 enum hprobe_state state;
118 int srcu_idx;
119 struct uprobe *uprobe;
120 };
121
122 /*
123 * uprobe_task: Metadata of a task while it singlesteps.
124 */
125 struct uprobe_task {
126 enum uprobe_task_state state;
127
128 unsigned int depth;
129 struct return_instance *return_instances;
130
131 struct return_instance *ri_pool;
132 struct timer_list ri_timer;
133 seqcount_t ri_seqcount;
134
135 union {
136 struct {
137 struct arch_uprobe_task autask;
138 unsigned long vaddr;
139 };
140
141 struct {
142 struct callback_head dup_xol_work;
143 unsigned long dup_xol_addr;
144 };
145 };
146
147 struct uprobe *active_uprobe;
148 unsigned long xol_vaddr;
149 bool signal_denied;
150
151 struct arch_uprobe *auprobe;
152 };
153
154 struct return_consumer {
155 __u64 cookie;
156 __u64 id;
157 };
158
159 struct return_instance {
160 struct hprobe hprobe;
161 unsigned long func;
162 unsigned long stack; /* stack pointer */
163 unsigned long orig_ret_vaddr; /* original return address */
164 bool chained; /* true, if instance is nested */
165 int cons_cnt; /* total number of session consumers */
166
167 struct return_instance *next; /* keep as stack */
168 struct rcu_head rcu;
169
170 /* singular pre-allocated return_consumer instance for common case */
171 struct return_consumer consumer;
172 /*
173 * extra return_consumer instances for rare cases of multiple session consumers,
174 * contains (cons_cnt - 1) elements
175 */
176 struct return_consumer *extra_consumers;
177 } ____cacheline_aligned;
178
179 enum rp_check {
180 RP_CHECK_CALL,
181 RP_CHECK_CHAIN_CALL,
182 RP_CHECK_RET,
183 };
184
185 struct xol_area;
186
187 struct uprobes_state {
188 struct xol_area *xol_area;
189 #ifdef CONFIG_X86_64
190 struct hlist_head head_tramps;
191 #endif
192 };
193
194 typedef int (*uprobe_write_verify_t)(struct page *page, unsigned long vaddr,
195 uprobe_opcode_t *insn, int nbytes, void *data);
196
197 extern void __init uprobes_init(void);
198 extern int set_swbp(struct arch_uprobe *aup, struct vm_area_struct *vma, unsigned long vaddr);
199 extern int set_orig_insn(struct arch_uprobe *aup, struct vm_area_struct *vma, unsigned long vaddr);
200 extern bool is_swbp_insn(uprobe_opcode_t *insn);
201 extern bool is_trap_insn(uprobe_opcode_t *insn);
202 extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
203 extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
204 extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma, unsigned long vaddr, uprobe_opcode_t,
205 bool is_register);
206 extern int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma, const unsigned long opcode_vaddr,
207 uprobe_opcode_t *insn, int nbytes, uprobe_write_verify_t verify, bool is_register, bool do_update_ref_ctr,
208 void *data);
209 extern struct uprobe *uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
210 extern int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool);
211 extern void uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc);
212 extern void uprobe_unregister_sync(void);
213 extern int uprobe_mmap(struct vm_area_struct *vma);
214 extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end);
215 extern void uprobe_start_dup_mmap(void);
216 extern void uprobe_end_dup_mmap(void);
217 extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm);
218 extern void uprobe_free_utask(struct task_struct *t);
219 extern void uprobe_copy_process(struct task_struct *t, u64 flags);
220 extern int uprobe_post_sstep_notifier(struct pt_regs *regs);
221 extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
222 extern void uprobe_notify_resume(struct pt_regs *regs);
223 extern bool uprobe_deny_signal(void);
224 extern bool arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs);
225 extern void uprobe_clear_state(struct mm_struct *mm);
226 extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
227 extern int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
228 extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
229 extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
230 extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
231 extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
232 extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
233 extern bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, struct pt_regs *regs);
234 extern bool arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
235 extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
236 void *src, unsigned long len);
237 extern void uprobe_handle_trampoline(struct pt_regs *regs);
238 extern void *arch_uretprobe_trampoline(unsigned long *psize);
239 extern unsigned long uprobe_get_trampoline_vaddr(void);
240 extern void uprobe_copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len);
241 extern void arch_uprobe_clear_state(struct mm_struct *mm);
242 extern void arch_uprobe_init_state(struct mm_struct *mm);
243 extern void handle_syscall_uprobe(struct pt_regs *regs, unsigned long bp_vaddr);
244 extern void arch_uprobe_optimize(struct arch_uprobe *auprobe, unsigned long vaddr);
245 #else /* !CONFIG_UPROBES */
246 struct uprobes_state {
247 };
248
uprobes_init(void)249 static inline void uprobes_init(void)
250 {
251 }
252
253 #define uprobe_get_trap_addr(regs) instruction_pointer(regs)
254
255 static inline struct uprobe *
uprobe_register(struct inode * inode,loff_t offset,loff_t ref_ctr_offset,struct uprobe_consumer * uc)256 uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc)
257 {
258 return ERR_PTR(-ENOSYS);
259 }
260 static inline int
uprobe_apply(struct uprobe * uprobe,struct uprobe_consumer * uc,bool add)261 uprobe_apply(struct uprobe* uprobe, struct uprobe_consumer *uc, bool add)
262 {
263 return -ENOSYS;
264 }
265 static inline void
uprobe_unregister_nosync(struct uprobe * uprobe,struct uprobe_consumer * uc)266 uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc)
267 {
268 }
uprobe_unregister_sync(void)269 static inline void uprobe_unregister_sync(void)
270 {
271 }
uprobe_mmap(struct vm_area_struct * vma)272 static inline int uprobe_mmap(struct vm_area_struct *vma)
273 {
274 return 0;
275 }
276 static inline void
uprobe_munmap(struct vm_area_struct * vma,unsigned long start,unsigned long end)277 uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
278 {
279 }
uprobe_start_dup_mmap(void)280 static inline void uprobe_start_dup_mmap(void)
281 {
282 }
uprobe_end_dup_mmap(void)283 static inline void uprobe_end_dup_mmap(void)
284 {
285 }
286 static inline void
uprobe_dup_mmap(struct mm_struct * oldmm,struct mm_struct * newmm)287 uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
288 {
289 }
uprobe_notify_resume(struct pt_regs * regs)290 static inline void uprobe_notify_resume(struct pt_regs *regs)
291 {
292 }
uprobe_deny_signal(void)293 static inline bool uprobe_deny_signal(void)
294 {
295 return false;
296 }
uprobe_free_utask(struct task_struct * t)297 static inline void uprobe_free_utask(struct task_struct *t)
298 {
299 }
uprobe_copy_process(struct task_struct * t,u64 flags)300 static inline void uprobe_copy_process(struct task_struct *t, u64 flags)
301 {
302 }
uprobe_clear_state(struct mm_struct * mm)303 static inline void uprobe_clear_state(struct mm_struct *mm)
304 {
305 }
306 #endif /* !CONFIG_UPROBES */
307 #endif /* _LINUX_UPROBES_H */
308