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2522fe45 | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
bdf88217 RM |
2 | /* |
3 | * User-mode machine state access | |
4 | * | |
5 | * Copyright (C) 2007 Red Hat, Inc. All rights reserved. | |
6 | * | |
bdf88217 RM |
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> | |
187f1882 | 15 | #include <linux/bug.h> |
bae3f7c3 | 16 | #include <linux/uaccess.h> |
bdf88217 RM |
17 | struct task_struct; |
18 | struct user_regset; | |
19 | ||
20 | ||
21 | /** | |
22 | * user_regset_active_fn - type of @active function in &struct user_regset | |
23 | * @target: thread being examined | |
24 | * @regset: regset being examined | |
25 | * | |
26 | * Return -%ENODEV if not available on the hardware found. | |
27 | * Return %0 if no interesting state in this thread. | |
28 | * Return >%0 number of @size units of interesting state. | |
29 | * Any get call fetching state beyond that number will | |
30 | * see the default initialization state for this data, | |
31 | * so a caller that knows what the default state is need | |
32 | * not copy it all out. | |
33 | * This call is optional; the pointer is %NULL if there | |
34 | * is no inexpensive check to yield a value < @n. | |
35 | */ | |
36 | typedef int user_regset_active_fn(struct task_struct *target, | |
37 | const struct user_regset *regset); | |
38 | ||
39 | /** | |
40 | * user_regset_get_fn - type of @get function in &struct user_regset | |
41 | * @target: thread being examined | |
42 | * @regset: regset being examined | |
43 | * @pos: offset into the regset data to access, in bytes | |
44 | * @count: amount of data to copy, in bytes | |
45 | * @kbuf: if not %NULL, a kernel-space pointer to copy into | |
46 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy into | |
47 | * | |
48 | * Fetch register values. Return %0 on success; -%EIO or -%ENODEV | |
49 | * are usual failure returns. The @pos and @count values are in | |
50 | * bytes, but must be properly aligned. If @kbuf is non-null, that | |
51 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then | |
52 | * ubuf gives a userland pointer to access directly, and an -%EFAULT | |
53 | * return value is possible. | |
54 | */ | |
55 | typedef int user_regset_get_fn(struct task_struct *target, | |
56 | const struct user_regset *regset, | |
57 | unsigned int pos, unsigned int count, | |
58 | void *kbuf, void __user *ubuf); | |
59 | ||
60 | /** | |
61 | * user_regset_set_fn - type of @set function in &struct user_regset | |
62 | * @target: thread being examined | |
63 | * @regset: regset being examined | |
64 | * @pos: offset into the regset data to access, in bytes | |
65 | * @count: amount of data to copy, in bytes | |
66 | * @kbuf: if not %NULL, a kernel-space pointer to copy from | |
67 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy from | |
68 | * | |
69 | * Store register values. Return %0 on success; -%EIO or -%ENODEV | |
70 | * are usual failure returns. The @pos and @count values are in | |
71 | * bytes, but must be properly aligned. If @kbuf is non-null, that | |
72 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then | |
73 | * ubuf gives a userland pointer to access directly, and an -%EFAULT | |
74 | * return value is possible. | |
75 | */ | |
76 | typedef int user_regset_set_fn(struct task_struct *target, | |
77 | const struct user_regset *regset, | |
78 | unsigned int pos, unsigned int count, | |
79 | const void *kbuf, const void __user *ubuf); | |
80 | ||
81 | /** | |
82 | * user_regset_writeback_fn - type of @writeback function in &struct user_regset | |
83 | * @target: thread being examined | |
84 | * @regset: regset being examined | |
85 | * @immediate: zero if writeback at completion of next context switch is OK | |
86 | * | |
87 | * This call is optional; usually the pointer is %NULL. When | |
88 | * provided, there is some user memory associated with this regset's | |
89 | * hardware, such as memory backing cached register data on register | |
90 | * window machines; the regset's data controls what user memory is | |
91 | * used (e.g. via the stack pointer value). | |
92 | * | |
93 | * Write register data back to user memory. If the @immediate flag | |
94 | * is nonzero, it must be written to the user memory so uaccess or | |
95 | * access_process_vm() can see it when this call returns; if zero, | |
96 | * then it must be written back by the time the task completes a | |
97 | * context switch (as synchronized with wait_task_inactive()). | |
98 | * Return %0 on success or if there was nothing to do, -%EFAULT for | |
99 | * a memory problem (bad stack pointer or whatever), or -%EIO for a | |
100 | * hardware problem. | |
101 | */ | |
102 | typedef int user_regset_writeback_fn(struct task_struct *target, | |
103 | const struct user_regset *regset, | |
104 | int immediate); | |
105 | ||
27e64b4b DM |
106 | /** |
107 | * user_regset_get_size_fn - type of @get_size function in &struct user_regset | |
108 | * @target: thread being examined | |
109 | * @regset: regset being examined | |
110 | * | |
111 | * This call is optional; usually the pointer is %NULL. | |
112 | * | |
113 | * When provided, this function must return the current size of regset | |
114 | * data, as observed by the @get function in &struct user_regset. The | |
115 | * value returned must be a multiple of @size. The returned size is | |
116 | * required to be valid only until the next time (if any) @regset is | |
117 | * modified for @target. | |
118 | * | |
119 | * This function is intended for dynamically sized regsets. A regset | |
120 | * that is statically sized does not need to implement it. | |
121 | * | |
122 | * This function should not be called directly: instead, callers should | |
123 | * call regset_size() to determine the current size of a regset. | |
124 | */ | |
125 | typedef unsigned int user_regset_get_size_fn(struct task_struct *target, | |
126 | const struct user_regset *regset); | |
127 | ||
bdf88217 RM |
128 | /** |
129 | * struct user_regset - accessible thread CPU state | |
130 | * @n: Number of slots (registers). | |
131 | * @size: Size in bytes of a slot (register). | |
132 | * @align: Required alignment, in bytes. | |
133 | * @bias: Bias from natural indexing. | |
134 | * @core_note_type: ELF note @n_type value used in core dumps. | |
135 | * @get: Function to fetch values. | |
136 | * @set: Function to store values. | |
137 | * @active: Function to report if regset is active, or %NULL. | |
138 | * @writeback: Function to write data back to user memory, or %NULL. | |
27e64b4b | 139 | * @get_size: Function to return the regset's size, or %NULL. |
bdf88217 RM |
140 | * |
141 | * This data structure describes a machine resource we call a register set. | |
142 | * This is part of the state of an individual thread, not necessarily | |
143 | * actual CPU registers per se. A register set consists of a number of | |
144 | * similar slots, given by @n. Each slot is @size bytes, and aligned to | |
27e64b4b DM |
145 | * @align bytes (which is at least @size). For dynamically-sized |
146 | * regsets, @n must contain the maximum possible number of slots for the | |
147 | * regset, and @get_size must point to a function that returns the | |
148 | * current regset size. | |
bdf88217 | 149 | * |
27e64b4b DM |
150 | * Callers that need to know only the current size of the regset and do |
151 | * not care about its internal structure should call regset_size() | |
152 | * instead of inspecting @n or calling @get_size. | |
153 | * | |
154 | * For backward compatibility, the @get and @set methods must pad to, or | |
155 | * accept, @n * @size bytes, even if the current regset size is smaller. | |
156 | * The precise semantics of these operations depend on the regset being | |
157 | * accessed. | |
158 | * | |
159 | * The functions to which &struct user_regset members point must be | |
160 | * called only on the current thread or on a thread that is in | |
161 | * %TASK_STOPPED or %TASK_TRACED state, that we are guaranteed will not | |
162 | * be woken up and return to user mode, and that we have called | |
163 | * wait_task_inactive() on. (The target thread always might wake up for | |
164 | * SIGKILL while these functions are working, in which case that | |
165 | * thread's user_regset state might be scrambled.) | |
bdf88217 RM |
166 | * |
167 | * The @pos argument must be aligned according to @align; the @count | |
168 | * argument must be a multiple of @size. These functions are not | |
169 | * responsible for checking for invalid arguments. | |
170 | * | |
171 | * When there is a natural value to use as an index, @bias gives the | |
172 | * difference between the natural index and the slot index for the | |
173 | * register set. For example, x86 GDT segment descriptors form a regset; | |
174 | * the segment selector produces a natural index, but only a subset of | |
175 | * that index space is available as a regset (the TLS slots); subtracting | |
176 | * @bias from a segment selector index value computes the regset slot. | |
177 | * | |
178 | * If nonzero, @core_note_type gives the n_type field (NT_* value) | |
179 | * of the core file note in which this regset's data appears. | |
180 | * NT_PRSTATUS is a special case in that the regset data starts at | |
181 | * offsetof(struct elf_prstatus, pr_reg) into the note data; that is | |
182 | * part of the per-machine ELF formats userland knows about. In | |
183 | * other cases, the core file note contains exactly the whole regset | |
184 | * (@n * @size) and nothing else. The core file note is normally | |
185 | * omitted when there is an @active function and it returns zero. | |
186 | */ | |
187 | struct user_regset { | |
188 | user_regset_get_fn *get; | |
189 | user_regset_set_fn *set; | |
190 | user_regset_active_fn *active; | |
191 | user_regset_writeback_fn *writeback; | |
27e64b4b | 192 | user_regset_get_size_fn *get_size; |
bdf88217 RM |
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 | ||
bae3f7c3 RM |
242 | /* |
243 | * These are helpers for writing regset get/set functions in arch code. | |
244 | * Because @start_pos and @end_pos are always compile-time constants, | |
245 | * these are inlined into very little code though they look large. | |
246 | * | |
247 | * Use one or more calls sequentially for each chunk of regset data stored | |
248 | * contiguously in memory. Call with constants for @start_pos and @end_pos, | |
249 | * giving the range of byte positions in the regset that data corresponds | |
250 | * to; @end_pos can be -1 if this chunk is at the end of the regset layout. | |
251 | * Each call updates the arguments to point past its chunk. | |
252 | */ | |
253 | ||
254 | static inline int user_regset_copyout(unsigned int *pos, unsigned int *count, | |
255 | void **kbuf, | |
256 | void __user **ubuf, const void *data, | |
257 | const int start_pos, const int end_pos) | |
258 | { | |
259 | if (*count == 0) | |
260 | return 0; | |
261 | BUG_ON(*pos < start_pos); | |
262 | if (end_pos < 0 || *pos < end_pos) { | |
263 | unsigned int copy = (end_pos < 0 ? *count | |
264 | : min(*count, end_pos - *pos)); | |
265 | data += *pos - start_pos; | |
266 | if (*kbuf) { | |
267 | memcpy(*kbuf, data, copy); | |
268 | *kbuf += copy; | |
269 | } else if (__copy_to_user(*ubuf, data, copy)) | |
270 | return -EFAULT; | |
271 | else | |
272 | *ubuf += copy; | |
273 | *pos += copy; | |
274 | *count -= copy; | |
275 | } | |
276 | return 0; | |
277 | } | |
278 | ||
279 | static inline int user_regset_copyin(unsigned int *pos, unsigned int *count, | |
280 | const void **kbuf, | |
281 | const void __user **ubuf, void *data, | |
282 | const int start_pos, const int end_pos) | |
283 | { | |
284 | if (*count == 0) | |
285 | return 0; | |
286 | BUG_ON(*pos < start_pos); | |
287 | if (end_pos < 0 || *pos < end_pos) { | |
288 | unsigned int copy = (end_pos < 0 ? *count | |
289 | : min(*count, end_pos - *pos)); | |
290 | data += *pos - start_pos; | |
291 | if (*kbuf) { | |
292 | memcpy(data, *kbuf, copy); | |
293 | *kbuf += copy; | |
294 | } else if (__copy_from_user(data, *ubuf, copy)) | |
295 | return -EFAULT; | |
296 | else | |
297 | *ubuf += copy; | |
298 | *pos += copy; | |
299 | *count -= copy; | |
300 | } | |
301 | return 0; | |
302 | } | |
303 | ||
304 | /* | |
305 | * These two parallel the two above, but for portions of a regset layout | |
306 | * that always read as all-zero or for which writes are ignored. | |
307 | */ | |
308 | static inline int user_regset_copyout_zero(unsigned int *pos, | |
309 | unsigned int *count, | |
310 | void **kbuf, void __user **ubuf, | |
311 | const int start_pos, | |
312 | const int end_pos) | |
313 | { | |
314 | if (*count == 0) | |
315 | return 0; | |
316 | BUG_ON(*pos < start_pos); | |
317 | if (end_pos < 0 || *pos < end_pos) { | |
318 | unsigned int copy = (end_pos < 0 ? *count | |
319 | : min(*count, end_pos - *pos)); | |
320 | if (*kbuf) { | |
321 | memset(*kbuf, 0, copy); | |
322 | *kbuf += copy; | |
323 | } else if (__clear_user(*ubuf, copy)) | |
324 | return -EFAULT; | |
325 | else | |
326 | *ubuf += copy; | |
327 | *pos += copy; | |
328 | *count -= copy; | |
329 | } | |
330 | return 0; | |
331 | } | |
332 | ||
333 | static inline int user_regset_copyin_ignore(unsigned int *pos, | |
334 | unsigned int *count, | |
335 | const void **kbuf, | |
336 | const void __user **ubuf, | |
337 | const int start_pos, | |
338 | const int end_pos) | |
339 | { | |
340 | if (*count == 0) | |
341 | return 0; | |
342 | BUG_ON(*pos < start_pos); | |
343 | if (end_pos < 0 || *pos < end_pos) { | |
344 | unsigned int copy = (end_pos < 0 ? *count | |
345 | : min(*count, end_pos - *pos)); | |
346 | if (*kbuf) | |
347 | *kbuf += copy; | |
348 | else | |
349 | *ubuf += copy; | |
350 | *pos += copy; | |
351 | *count -= copy; | |
352 | } | |
353 | return 0; | |
354 | } | |
355 | ||
5bde4d18 RM |
356 | /** |
357 | * copy_regset_to_user - fetch a thread's user_regset data into user memory | |
358 | * @target: thread to be examined | |
359 | * @view: &struct user_regset_view describing user thread machine state | |
360 | * @setno: index in @view->regsets | |
361 | * @offset: offset into the regset data, in bytes | |
362 | * @size: amount of data to copy, in bytes | |
363 | * @data: user-mode pointer to copy into | |
364 | */ | |
365 | static inline int copy_regset_to_user(struct task_struct *target, | |
366 | const struct user_regset_view *view, | |
367 | unsigned int setno, | |
368 | unsigned int offset, unsigned int size, | |
369 | void __user *data) | |
370 | { | |
371 | const struct user_regset *regset = &view->regsets[setno]; | |
372 | ||
c8e25258 PA |
373 | if (!regset->get) |
374 | return -EOPNOTSUPP; | |
375 | ||
96d4f267 | 376 | if (!access_ok(data, size)) |
5189fa19 | 377 | return -EFAULT; |
5bde4d18 RM |
378 | |
379 | return regset->get(target, regset, offset, size, NULL, data); | |
380 | } | |
381 | ||
382 | /** | |
383 | * copy_regset_from_user - store into thread's user_regset data from user memory | |
384 | * @target: thread to be examined | |
385 | * @view: &struct user_regset_view describing user thread machine state | |
386 | * @setno: index in @view->regsets | |
387 | * @offset: offset into the regset data, in bytes | |
388 | * @size: amount of data to copy, in bytes | |
389 | * @data: user-mode pointer to copy from | |
390 | */ | |
391 | static inline int copy_regset_from_user(struct task_struct *target, | |
392 | const struct user_regset_view *view, | |
393 | unsigned int setno, | |
394 | unsigned int offset, unsigned int size, | |
395 | const void __user *data) | |
396 | { | |
397 | const struct user_regset *regset = &view->regsets[setno]; | |
398 | ||
c8e25258 PA |
399 | if (!regset->set) |
400 | return -EOPNOTSUPP; | |
401 | ||
96d4f267 | 402 | if (!access_ok(data, size)) |
5189fa19 | 403 | return -EFAULT; |
5bde4d18 RM |
404 | |
405 | return regset->set(target, regset, offset, size, NULL, data); | |
406 | } | |
407 | ||
27e64b4b DM |
408 | /** |
409 | * regset_size - determine the current size of a regset | |
410 | * @target: thread to be examined | |
411 | * @regset: regset to be examined | |
412 | * | |
413 | * Note that the returned size is valid only until the next time | |
414 | * (if any) @regset is modified for @target. | |
415 | */ | |
416 | static inline unsigned int regset_size(struct task_struct *target, | |
417 | const struct user_regset *regset) | |
418 | { | |
419 | if (!regset->get_size) | |
420 | return regset->n * regset->size; | |
421 | else | |
422 | return regset->get_size(target, regset); | |
423 | } | |
bae3f7c3 | 424 | |
bdf88217 | 425 | #endif /* <linux/regset.h> */ |