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1 | /* SPDX-License-Identifier: GPL-2.0-only */ | |
2 | /* | |
3 | * User-mode machine state access | |
4 | * | |
5 | * Copyright (C) 2007 Red Hat, Inc. All rights reserved. | |
6 | * | |
7 | * Red Hat Author: Roland McGrath. | |
8 | */ | |
9 | ||
10 | #ifndef _LINUX_REGSET_H | |
11 | #define _LINUX_REGSET_H 1 | |
12 | ||
13 | #include <linux/compiler.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/bug.h> | |
16 | #include <linux/uaccess.h> | |
17 | struct task_struct; | |
18 | struct user_regset; | |
19 | ||
20 | struct membuf { | |
21 | void *p; | |
22 | size_t left; | |
23 | }; | |
24 | ||
25 | static inline int membuf_zero(struct membuf *s, size_t size) | |
26 | { | |
27 | if (s->left) { | |
28 | if (size > s->left) | |
29 | size = s->left; | |
30 | memset(s->p, 0, size); | |
31 | s->p += size; | |
32 | s->left -= size; | |
33 | } | |
34 | return s->left; | |
35 | } | |
36 | ||
37 | static inline int membuf_write(struct membuf *s, const void *v, size_t size) | |
38 | { | |
39 | if (s->left) { | |
40 | if (size > s->left) | |
41 | size = s->left; | |
42 | memcpy(s->p, v, size); | |
43 | s->p += size; | |
44 | s->left -= size; | |
45 | } | |
46 | return s->left; | |
47 | } | |
48 | ||
49 | /* current s->p must be aligned for v; v must be a scalar */ | |
50 | #define membuf_store(s, v) \ | |
51 | ({ \ | |
52 | struct membuf *__s = (s); \ | |
53 | if (__s->left) { \ | |
54 | typeof(v) __v = (v); \ | |
55 | size_t __size = sizeof(__v); \ | |
56 | if (unlikely(__size > __s->left)) { \ | |
57 | __size = __s->left; \ | |
58 | memcpy(__s->p, &__v, __size); \ | |
59 | } else { \ | |
60 | *(typeof(__v + 0) *)__s->p = __v; \ | |
61 | } \ | |
62 | __s->p += __size; \ | |
63 | __s->left -= __size; \ | |
64 | } \ | |
65 | __s->left;}) | |
66 | ||
67 | /** | |
68 | * user_regset_active_fn - type of @active function in &struct user_regset | |
69 | * @target: thread being examined | |
70 | * @regset: regset being examined | |
71 | * | |
72 | * Return -%ENODEV if not available on the hardware found. | |
73 | * Return %0 if no interesting state in this thread. | |
74 | * Return >%0 number of @size units of interesting state. | |
75 | * Any get call fetching state beyond that number will | |
76 | * see the default initialization state for this data, | |
77 | * so a caller that knows what the default state is need | |
78 | * not copy it all out. | |
79 | * This call is optional; the pointer is %NULL if there | |
80 | * is no inexpensive check to yield a value < @n. | |
81 | */ | |
82 | typedef int user_regset_active_fn(struct task_struct *target, | |
83 | const struct user_regset *regset); | |
84 | ||
85 | typedef int user_regset_get2_fn(struct task_struct *target, | |
86 | const struct user_regset *regset, | |
87 | struct membuf to); | |
88 | ||
89 | /** | |
90 | * user_regset_set_fn - type of @set function in &struct user_regset | |
91 | * @target: thread being examined | |
92 | * @regset: regset being examined | |
93 | * @pos: offset into the regset data to access, in bytes | |
94 | * @count: amount of data to copy, in bytes | |
95 | * @kbuf: if not %NULL, a kernel-space pointer to copy from | |
96 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy from | |
97 | * | |
98 | * Store register values. Return %0 on success; -%EIO or -%ENODEV | |
99 | * are usual failure returns. The @pos and @count values are in | |
100 | * bytes, but must be properly aligned. If @kbuf is non-null, that | |
101 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then | |
102 | * ubuf gives a userland pointer to access directly, and an -%EFAULT | |
103 | * return value is possible. | |
104 | */ | |
105 | typedef int user_regset_set_fn(struct task_struct *target, | |
106 | const struct user_regset *regset, | |
107 | unsigned int pos, unsigned int count, | |
108 | const void *kbuf, const void __user *ubuf); | |
109 | ||
110 | /** | |
111 | * user_regset_writeback_fn - type of @writeback function in &struct user_regset | |
112 | * @target: thread being examined | |
113 | * @regset: regset being examined | |
114 | * @immediate: zero if writeback at completion of next context switch is OK | |
115 | * | |
116 | * This call is optional; usually the pointer is %NULL. When | |
117 | * provided, there is some user memory associated with this regset's | |
118 | * hardware, such as memory backing cached register data on register | |
119 | * window machines; the regset's data controls what user memory is | |
120 | * used (e.g. via the stack pointer value). | |
121 | * | |
122 | * Write register data back to user memory. If the @immediate flag | |
123 | * is nonzero, it must be written to the user memory so uaccess or | |
124 | * access_process_vm() can see it when this call returns; if zero, | |
125 | * then it must be written back by the time the task completes a | |
126 | * context switch (as synchronized with wait_task_inactive()). | |
127 | * Return %0 on success or if there was nothing to do, -%EFAULT for | |
128 | * a memory problem (bad stack pointer or whatever), or -%EIO for a | |
129 | * hardware problem. | |
130 | */ | |
131 | typedef int user_regset_writeback_fn(struct task_struct *target, | |
132 | const struct user_regset *regset, | |
133 | int immediate); | |
134 | ||
135 | /** | |
136 | * struct user_regset - accessible thread CPU state | |
137 | * @n: Number of slots (registers). | |
138 | * @size: Size in bytes of a slot (register). | |
139 | * @align: Required alignment, in bytes. | |
140 | * @bias: Bias from natural indexing. | |
141 | * @core_note_type: ELF note @n_type value used in core dumps. | |
142 | * @get: Function to fetch values. | |
143 | * @set: Function to store values. | |
144 | * @active: Function to report if regset is active, or %NULL. | |
145 | * @writeback: Function to write data back to user memory, or %NULL. | |
146 | * | |
147 | * This data structure describes a machine resource we call a register set. | |
148 | * This is part of the state of an individual thread, not necessarily | |
149 | * actual CPU registers per se. A register set consists of a number of | |
150 | * similar slots, given by @n. Each slot is @size bytes, and aligned to | |
151 | * @align bytes (which is at least @size). For dynamically-sized | |
152 | * regsets, @n must contain the maximum possible number of slots for the | |
153 | * regset. | |
154 | * | |
155 | * For backward compatibility, the @get and @set methods must pad to, or | |
156 | * accept, @n * @size bytes, even if the current regset size is smaller. | |
157 | * The precise semantics of these operations depend on the regset being | |
158 | * accessed. | |
159 | * | |
160 | * The functions to which &struct user_regset members point must be | |
161 | * called only on the current thread or on a thread that is in | |
162 | * %TASK_STOPPED or %TASK_TRACED state, that we are guaranteed will not | |
163 | * be woken up and return to user mode, and that we have called | |
164 | * wait_task_inactive() on. (The target thread always might wake up for | |
165 | * SIGKILL while these functions are working, in which case that | |
166 | * thread's user_regset state might be scrambled.) | |
167 | * | |
168 | * The @pos argument must be aligned according to @align; the @count | |
169 | * argument must be a multiple of @size. These functions are not | |
170 | * responsible for checking for invalid arguments. | |
171 | * | |
172 | * When there is a natural value to use as an index, @bias gives the | |
173 | * difference between the natural index and the slot index for the | |
174 | * register set. For example, x86 GDT segment descriptors form a regset; | |
175 | * the segment selector produces a natural index, but only a subset of | |
176 | * that index space is available as a regset (the TLS slots); subtracting | |
177 | * @bias from a segment selector index value computes the regset slot. | |
178 | * | |
179 | * If nonzero, @core_note_type gives the n_type field (NT_* value) | |
180 | * of the core file note in which this regset's data appears. | |
181 | * NT_PRSTATUS is a special case in that the regset data starts at | |
182 | * offsetof(struct elf_prstatus, pr_reg) into the note data; that is | |
183 | * part of the per-machine ELF formats userland knows about. In | |
184 | * other cases, the core file note contains exactly the whole regset | |
185 | * (@n * @size) and nothing else. The core file note is normally | |
186 | * omitted when there is an @active function and it returns zero. | |
187 | */ | |
188 | struct user_regset { | |
189 | user_regset_get2_fn *regset_get; | |
190 | user_regset_set_fn *set; | |
191 | user_regset_active_fn *active; | |
192 | user_regset_writeback_fn *writeback; | |
193 | unsigned int n; | |
194 | unsigned int size; | |
195 | unsigned int align; | |
196 | unsigned int bias; | |
197 | unsigned int core_note_type; | |
198 | }; | |
199 | ||
200 | /** | |
201 | * struct user_regset_view - available regsets | |
202 | * @name: Identifier, e.g. UTS_MACHINE string. | |
203 | * @regsets: Array of @n regsets available in this view. | |
204 | * @n: Number of elements in @regsets. | |
205 | * @e_machine: ELF header @e_machine %EM_* value written in core dumps. | |
206 | * @e_flags: ELF header @e_flags value written in core dumps. | |
207 | * @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps. | |
208 | * | |
209 | * A regset view is a collection of regsets (&struct user_regset, | |
210 | * above). This describes all the state of a thread that can be seen | |
211 | * from a given architecture/ABI environment. More than one view might | |
212 | * refer to the same &struct user_regset, or more than one regset | |
213 | * might refer to the same machine-specific state in the thread. For | |
214 | * example, a 32-bit thread's state could be examined from the 32-bit | |
215 | * view or from the 64-bit view. Either method reaches the same thread | |
216 | * register state, doing appropriate widening or truncation. | |
217 | */ | |
218 | struct user_regset_view { | |
219 | const char *name; | |
220 | const struct user_regset *regsets; | |
221 | unsigned int n; | |
222 | u32 e_flags; | |
223 | u16 e_machine; | |
224 | u8 ei_osabi; | |
225 | }; | |
226 | ||
227 | /* | |
228 | * This is documented here rather than at the definition sites because its | |
229 | * implementation is machine-dependent but its interface is universal. | |
230 | */ | |
231 | /** | |
232 | * task_user_regset_view - Return the process's native regset view. | |
233 | * @tsk: a thread of the process in question | |
234 | * | |
235 | * Return the &struct user_regset_view that is native for the given process. | |
236 | * For example, what it would access when it called ptrace(). | |
237 | * Throughout the life of the process, this only changes at exec. | |
238 | */ | |
239 | const struct user_regset_view *task_user_regset_view(struct task_struct *tsk); | |
240 | ||
241 | static inline int user_regset_copyin(unsigned int *pos, unsigned int *count, | |
242 | const void **kbuf, | |
243 | const void __user **ubuf, void *data, | |
244 | const int start_pos, const int end_pos) | |
245 | { | |
246 | if (*count == 0) | |
247 | return 0; | |
248 | BUG_ON(*pos < start_pos); | |
249 | if (end_pos < 0 || *pos < end_pos) { | |
250 | unsigned int copy = (end_pos < 0 ? *count | |
251 | : min(*count, end_pos - *pos)); | |
252 | data += *pos - start_pos; | |
253 | if (*kbuf) { | |
254 | memcpy(data, *kbuf, copy); | |
255 | *kbuf += copy; | |
256 | } else if (__copy_from_user(data, *ubuf, copy)) | |
257 | return -EFAULT; | |
258 | else | |
259 | *ubuf += copy; | |
260 | *pos += copy; | |
261 | *count -= copy; | |
262 | } | |
263 | return 0; | |
264 | } | |
265 | ||
266 | static inline int user_regset_copyin_ignore(unsigned int *pos, | |
267 | unsigned int *count, | |
268 | const void **kbuf, | |
269 | const void __user **ubuf, | |
270 | const int start_pos, | |
271 | const int end_pos) | |
272 | { | |
273 | if (*count == 0) | |
274 | return 0; | |
275 | BUG_ON(*pos < start_pos); | |
276 | if (end_pos < 0 || *pos < end_pos) { | |
277 | unsigned int copy = (end_pos < 0 ? *count | |
278 | : min(*count, end_pos - *pos)); | |
279 | if (*kbuf) | |
280 | *kbuf += copy; | |
281 | else | |
282 | *ubuf += copy; | |
283 | *pos += copy; | |
284 | *count -= copy; | |
285 | } | |
286 | return 0; | |
287 | } | |
288 | ||
289 | extern int regset_get(struct task_struct *target, | |
290 | const struct user_regset *regset, | |
291 | unsigned int size, void *data); | |
292 | ||
293 | extern int regset_get_alloc(struct task_struct *target, | |
294 | const struct user_regset *regset, | |
295 | unsigned int size, | |
296 | void **data); | |
297 | ||
298 | extern int copy_regset_to_user(struct task_struct *target, | |
299 | const struct user_regset_view *view, | |
300 | unsigned int setno, unsigned int offset, | |
301 | unsigned int size, void __user *data); | |
302 | ||
303 | /** | |
304 | * copy_regset_from_user - store into thread's user_regset data from user memory | |
305 | * @target: thread to be examined | |
306 | * @view: &struct user_regset_view describing user thread machine state | |
307 | * @setno: index in @view->regsets | |
308 | * @offset: offset into the regset data, in bytes | |
309 | * @size: amount of data to copy, in bytes | |
310 | * @data: user-mode pointer to copy from | |
311 | */ | |
312 | static inline int copy_regset_from_user(struct task_struct *target, | |
313 | const struct user_regset_view *view, | |
314 | unsigned int setno, | |
315 | unsigned int offset, unsigned int size, | |
316 | const void __user *data) | |
317 | { | |
318 | const struct user_regset *regset = &view->regsets[setno]; | |
319 | ||
320 | if (!regset->set) | |
321 | return -EOPNOTSUPP; | |
322 | ||
323 | if (!access_ok(data, size)) | |
324 | return -EFAULT; | |
325 | ||
326 | return regset->set(target, regset, offset, size, NULL, data); | |
327 | } | |
328 | ||
329 | #endif /* <linux/regset.h> */ |