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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 : :
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 : :
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 : :
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.
139 : : * @get_size: Function to return the regset's size, or %NULL.
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
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.
149 : : *
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.)
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;
192 : : user_regset_get_size_fn *get_size;
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 : :
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 : 0 : 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 : 0 : if (*count == 0)
260 : : return 0;
261 : 0 : BUG_ON(*pos < start_pos);
262 : 0 : if (end_pos < 0 || *pos < end_pos) {
263 : : unsigned int copy = (end_pos < 0 ? *count
264 : 0 : : min(*count, end_pos - *pos));
265 : 0 : data += *pos - start_pos;
266 : 0 : if (*kbuf) {
267 : 0 : memcpy(*kbuf, data, copy);
268 : 0 : *kbuf += copy;
269 : 0 : } else if (__copy_to_user(*ubuf, data, copy))
270 : : return -EFAULT;
271 : : else
272 : 0 : *ubuf += copy;
273 : 0 : *pos += copy;
274 : 0 : *count -= copy;
275 : : }
276 : : return 0;
277 : : }
278 : :
279 : 0 : 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 : 0 : if (*count == 0)
285 : : return 0;
286 : 0 : BUG_ON(*pos < start_pos);
287 : 0 : if (end_pos < 0 || *pos < end_pos) {
288 : : unsigned int copy = (end_pos < 0 ? *count
289 : 0 : : min(*count, end_pos - *pos));
290 : 0 : data += *pos - start_pos;
291 : 0 : if (*kbuf) {
292 : 0 : memcpy(data, *kbuf, copy);
293 : 0 : *kbuf += copy;
294 : 0 : } else if (__copy_from_user(data, *ubuf, copy))
295 : : return -EFAULT;
296 : : else
297 : 0 : *ubuf += copy;
298 : 0 : *pos += copy;
299 : 0 : *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 : 0 : 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 : 0 : if (*count == 0)
315 : : return 0;
316 : 0 : BUG_ON(*pos < start_pos);
317 : 0 : if (end_pos < 0 || *pos < end_pos) {
318 : : unsigned int copy = (end_pos < 0 ? *count
319 : 0 : : min(*count, end_pos - *pos));
320 : 0 : if (*kbuf) {
321 : 0 : memset(*kbuf, 0, copy);
322 : 0 : *kbuf += copy;
323 : 0 : } else if (__clear_user(*ubuf, copy))
324 : : return -EFAULT;
325 : : else
326 : 0 : *ubuf += copy;
327 : 0 : *pos += copy;
328 : 0 : *count -= copy;
329 : : }
330 : : return 0;
331 : : }
332 : :
333 : 0 : 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 : 0 : if (*count == 0)
341 : : return 0;
342 : 0 : BUG_ON(*pos < start_pos);
343 : 0 : if (end_pos < 0 || *pos < end_pos) {
344 : : unsigned int copy = (end_pos < 0 ? *count
345 : 0 : : min(*count, end_pos - *pos));
346 : 0 : if (*kbuf)
347 : 0 : *kbuf += copy;
348 : : else
349 : 0 : *ubuf += copy;
350 : 0 : *pos += copy;
351 : 0 : *count -= copy;
352 : : }
353 : : return 0;
354 : : }
355 : :
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 : 0 : 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 : 0 : const struct user_regset *regset = &view->regsets[setno];
372 : :
373 : 0 : if (!regset->get)
374 : : return -EOPNOTSUPP;
375 : :
376 : 0 : if (!access_ok(data, size))
377 : : return -EFAULT;
378 : :
379 : 0 : 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 : 0 : 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 : 0 : const struct user_regset *regset = &view->regsets[setno];
398 : :
399 : 0 : if (!regset->set)
400 : : return -EOPNOTSUPP;
401 : :
402 : 0 : if (!access_ok(data, size))
403 : : return -EFAULT;
404 : :
405 : 0 : return regset->set(target, regset, offset, size, NULL, data);
406 : : }
407 : :
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 : 0 : if (!regset->get_size)
420 : 0 : return regset->n * regset->size;
421 : : else
422 : 0 : return regset->get_size(target, regset);
423 : : }
424 : :
425 : : #endif /* <linux/regset.h> */
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