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bdf88217 RM |
1 | /* |
2 | * User-mode machine state access | |
3 | * | |
4 | * Copyright (C) 2007 Red Hat, Inc. All rights reserved. | |
5 | * | |
6 | * This copyrighted material is made available to anyone wishing to use, | |
7 | * modify, copy, or redistribute it subject to the terms and conditions | |
8 | * of the GNU General Public License v.2. | |
9 | * | |
10 | * Red Hat Author: Roland McGrath. | |
11 | */ | |
12 | ||
13 | #ifndef _LINUX_REGSET_H | |
14 | #define _LINUX_REGSET_H 1 | |
15 | ||
16 | #include <linux/compiler.h> | |
17 | #include <linux/types.h> | |
187f1882 | 18 | #include <linux/bug.h> |
bae3f7c3 | 19 | #include <linux/uaccess.h> |
bdf88217 RM |
20 | struct task_struct; |
21 | struct user_regset; | |
22 | ||
23 | ||
24 | /** | |
25 | * user_regset_active_fn - type of @active function in &struct user_regset | |
26 | * @target: thread being examined | |
27 | * @regset: regset being examined | |
28 | * | |
29 | * Return -%ENODEV if not available on the hardware found. | |
30 | * Return %0 if no interesting state in this thread. | |
31 | * Return >%0 number of @size units of interesting state. | |
32 | * Any get call fetching state beyond that number will | |
33 | * see the default initialization state for this data, | |
34 | * so a caller that knows what the default state is need | |
35 | * not copy it all out. | |
36 | * This call is optional; the pointer is %NULL if there | |
37 | * is no inexpensive check to yield a value < @n. | |
38 | */ | |
39 | typedef int user_regset_active_fn(struct task_struct *target, | |
40 | const struct user_regset *regset); | |
41 | ||
42 | /** | |
43 | * user_regset_get_fn - type of @get function in &struct user_regset | |
44 | * @target: thread being examined | |
45 | * @regset: regset being examined | |
46 | * @pos: offset into the regset data to access, in bytes | |
47 | * @count: amount of data to copy, in bytes | |
48 | * @kbuf: if not %NULL, a kernel-space pointer to copy into | |
49 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy into | |
50 | * | |
51 | * Fetch register values. Return %0 on success; -%EIO or -%ENODEV | |
52 | * are usual failure returns. The @pos and @count values are in | |
53 | * bytes, but must be properly aligned. If @kbuf is non-null, that | |
54 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then | |
55 | * ubuf gives a userland pointer to access directly, and an -%EFAULT | |
56 | * return value is possible. | |
57 | */ | |
58 | typedef int user_regset_get_fn(struct task_struct *target, | |
59 | const struct user_regset *regset, | |
60 | unsigned int pos, unsigned int count, | |
61 | void *kbuf, void __user *ubuf); | |
62 | ||
63 | /** | |
64 | * user_regset_set_fn - type of @set function in &struct user_regset | |
65 | * @target: thread being examined | |
66 | * @regset: regset being examined | |
67 | * @pos: offset into the regset data to access, in bytes | |
68 | * @count: amount of data to copy, in bytes | |
69 | * @kbuf: if not %NULL, a kernel-space pointer to copy from | |
70 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy from | |
71 | * | |
72 | * Store register values. Return %0 on success; -%EIO or -%ENODEV | |
73 | * are usual failure returns. The @pos and @count values are in | |
74 | * bytes, but must be properly aligned. If @kbuf is non-null, that | |
75 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then | |
76 | * ubuf gives a userland pointer to access directly, and an -%EFAULT | |
77 | * return value is possible. | |
78 | */ | |
79 | typedef int user_regset_set_fn(struct task_struct *target, | |
80 | const struct user_regset *regset, | |
81 | unsigned int pos, unsigned int count, | |
82 | const void *kbuf, const void __user *ubuf); | |
83 | ||
84 | /** | |
85 | * user_regset_writeback_fn - type of @writeback function in &struct user_regset | |
86 | * @target: thread being examined | |
87 | * @regset: regset being examined | |
88 | * @immediate: zero if writeback at completion of next context switch is OK | |
89 | * | |
90 | * This call is optional; usually the pointer is %NULL. When | |
91 | * provided, there is some user memory associated with this regset's | |
92 | * hardware, such as memory backing cached register data on register | |
93 | * window machines; the regset's data controls what user memory is | |
94 | * used (e.g. via the stack pointer value). | |
95 | * | |
96 | * Write register data back to user memory. If the @immediate flag | |
97 | * is nonzero, it must be written to the user memory so uaccess or | |
98 | * access_process_vm() can see it when this call returns; if zero, | |
99 | * then it must be written back by the time the task completes a | |
100 | * context switch (as synchronized with wait_task_inactive()). | |
101 | * Return %0 on success or if there was nothing to do, -%EFAULT for | |
102 | * a memory problem (bad stack pointer or whatever), or -%EIO for a | |
103 | * hardware problem. | |
104 | */ | |
105 | typedef int user_regset_writeback_fn(struct task_struct *target, | |
106 | const struct user_regset *regset, | |
107 | int immediate); | |
108 | ||
27e64b4b DM |
109 | /** |
110 | * user_regset_get_size_fn - type of @get_size function in &struct user_regset | |
111 | * @target: thread being examined | |
112 | * @regset: regset being examined | |
113 | * | |
114 | * This call is optional; usually the pointer is %NULL. | |
115 | * | |
116 | * When provided, this function must return the current size of regset | |
117 | * data, as observed by the @get function in &struct user_regset. The | |
118 | * value returned must be a multiple of @size. The returned size is | |
119 | * required to be valid only until the next time (if any) @regset is | |
120 | * modified for @target. | |
121 | * | |
122 | * This function is intended for dynamically sized regsets. A regset | |
123 | * that is statically sized does not need to implement it. | |
124 | * | |
125 | * This function should not be called directly: instead, callers should | |
126 | * call regset_size() to determine the current size of a regset. | |
127 | */ | |
128 | typedef unsigned int user_regset_get_size_fn(struct task_struct *target, | |
129 | const struct user_regset *regset); | |
130 | ||
bdf88217 RM |
131 | /** |
132 | * struct user_regset - accessible thread CPU state | |
133 | * @n: Number of slots (registers). | |
134 | * @size: Size in bytes of a slot (register). | |
135 | * @align: Required alignment, in bytes. | |
136 | * @bias: Bias from natural indexing. | |
137 | * @core_note_type: ELF note @n_type value used in core dumps. | |
138 | * @get: Function to fetch values. | |
139 | * @set: Function to store values. | |
140 | * @active: Function to report if regset is active, or %NULL. | |
141 | * @writeback: Function to write data back to user memory, or %NULL. | |
27e64b4b | 142 | * @get_size: Function to return the regset's size, or %NULL. |
bdf88217 RM |
143 | * |
144 | * This data structure describes a machine resource we call a register set. | |
145 | * This is part of the state of an individual thread, not necessarily | |
146 | * actual CPU registers per se. A register set consists of a number of | |
147 | * similar slots, given by @n. Each slot is @size bytes, and aligned to | |
27e64b4b DM |
148 | * @align bytes (which is at least @size). For dynamically-sized |
149 | * regsets, @n must contain the maximum possible number of slots for the | |
150 | * regset, and @get_size must point to a function that returns the | |
151 | * current regset size. | |
bdf88217 | 152 | * |
27e64b4b DM |
153 | * Callers that need to know only the current size of the regset and do |
154 | * not care about its internal structure should call regset_size() | |
155 | * instead of inspecting @n or calling @get_size. | |
156 | * | |
157 | * For backward compatibility, the @get and @set methods must pad to, or | |
158 | * accept, @n * @size bytes, even if the current regset size is smaller. | |
159 | * The precise semantics of these operations depend on the regset being | |
160 | * accessed. | |
161 | * | |
162 | * The functions to which &struct user_regset members point must be | |
163 | * called only on the current thread or on a thread that is in | |
164 | * %TASK_STOPPED or %TASK_TRACED state, that we are guaranteed will not | |
165 | * be woken up and return to user mode, and that we have called | |
166 | * wait_task_inactive() on. (The target thread always might wake up for | |
167 | * SIGKILL while these functions are working, in which case that | |
168 | * thread's user_regset state might be scrambled.) | |
bdf88217 RM |
169 | * |
170 | * The @pos argument must be aligned according to @align; the @count | |
171 | * argument must be a multiple of @size. These functions are not | |
172 | * responsible for checking for invalid arguments. | |
173 | * | |
174 | * When there is a natural value to use as an index, @bias gives the | |
175 | * difference between the natural index and the slot index for the | |
176 | * register set. For example, x86 GDT segment descriptors form a regset; | |
177 | * the segment selector produces a natural index, but only a subset of | |
178 | * that index space is available as a regset (the TLS slots); subtracting | |
179 | * @bias from a segment selector index value computes the regset slot. | |
180 | * | |
181 | * If nonzero, @core_note_type gives the n_type field (NT_* value) | |
182 | * of the core file note in which this regset's data appears. | |
183 | * NT_PRSTATUS is a special case in that the regset data starts at | |
184 | * offsetof(struct elf_prstatus, pr_reg) into the note data; that is | |
185 | * part of the per-machine ELF formats userland knows about. In | |
186 | * other cases, the core file note contains exactly the whole regset | |
187 | * (@n * @size) and nothing else. The core file note is normally | |
188 | * omitted when there is an @active function and it returns zero. | |
189 | */ | |
190 | struct user_regset { | |
191 | user_regset_get_fn *get; | |
192 | user_regset_set_fn *set; | |
193 | user_regset_active_fn *active; | |
194 | user_regset_writeback_fn *writeback; | |
27e64b4b | 195 | user_regset_get_size_fn *get_size; |
bdf88217 RM |
196 | unsigned int n; |
197 | unsigned int size; | |
198 | unsigned int align; | |
199 | unsigned int bias; | |
200 | unsigned int core_note_type; | |
201 | }; | |
202 | ||
203 | /** | |
204 | * struct user_regset_view - available regsets | |
205 | * @name: Identifier, e.g. UTS_MACHINE string. | |
206 | * @regsets: Array of @n regsets available in this view. | |
207 | * @n: Number of elements in @regsets. | |
208 | * @e_machine: ELF header @e_machine %EM_* value written in core dumps. | |
209 | * @e_flags: ELF header @e_flags value written in core dumps. | |
210 | * @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps. | |
211 | * | |
212 | * A regset view is a collection of regsets (&struct user_regset, | |
213 | * above). This describes all the state of a thread that can be seen | |
214 | * from a given architecture/ABI environment. More than one view might | |
215 | * refer to the same &struct user_regset, or more than one regset | |
216 | * might refer to the same machine-specific state in the thread. For | |
217 | * example, a 32-bit thread's state could be examined from the 32-bit | |
218 | * view or from the 64-bit view. Either method reaches the same thread | |
219 | * register state, doing appropriate widening or truncation. | |
220 | */ | |
221 | struct user_regset_view { | |
222 | const char *name; | |
223 | const struct user_regset *regsets; | |
224 | unsigned int n; | |
225 | u32 e_flags; | |
226 | u16 e_machine; | |
227 | u8 ei_osabi; | |
228 | }; | |
229 | ||
230 | /* | |
231 | * This is documented here rather than at the definition sites because its | |
232 | * implementation is machine-dependent but its interface is universal. | |
233 | */ | |
234 | /** | |
235 | * task_user_regset_view - Return the process's native regset view. | |
236 | * @tsk: a thread of the process in question | |
237 | * | |
238 | * Return the &struct user_regset_view that is native for the given process. | |
239 | * For example, what it would access when it called ptrace(). | |
240 | * Throughout the life of the process, this only changes at exec. | |
241 | */ | |
242 | const struct user_regset_view *task_user_regset_view(struct task_struct *tsk); | |
243 | ||
244 | ||
bae3f7c3 RM |
245 | /* |
246 | * These are helpers for writing regset get/set functions in arch code. | |
247 | * Because @start_pos and @end_pos are always compile-time constants, | |
248 | * these are inlined into very little code though they look large. | |
249 | * | |
250 | * Use one or more calls sequentially for each chunk of regset data stored | |
251 | * contiguously in memory. Call with constants for @start_pos and @end_pos, | |
252 | * giving the range of byte positions in the regset that data corresponds | |
253 | * to; @end_pos can be -1 if this chunk is at the end of the regset layout. | |
254 | * Each call updates the arguments to point past its chunk. | |
255 | */ | |
256 | ||
257 | static inline int user_regset_copyout(unsigned int *pos, unsigned int *count, | |
258 | void **kbuf, | |
259 | void __user **ubuf, const void *data, | |
260 | const int start_pos, const int end_pos) | |
261 | { | |
262 | if (*count == 0) | |
263 | return 0; | |
264 | BUG_ON(*pos < start_pos); | |
265 | if (end_pos < 0 || *pos < end_pos) { | |
266 | unsigned int copy = (end_pos < 0 ? *count | |
267 | : min(*count, end_pos - *pos)); | |
268 | data += *pos - start_pos; | |
269 | if (*kbuf) { | |
270 | memcpy(*kbuf, data, copy); | |
271 | *kbuf += copy; | |
272 | } else if (__copy_to_user(*ubuf, data, copy)) | |
273 | return -EFAULT; | |
274 | else | |
275 | *ubuf += copy; | |
276 | *pos += copy; | |
277 | *count -= copy; | |
278 | } | |
279 | return 0; | |
280 | } | |
281 | ||
282 | static inline int user_regset_copyin(unsigned int *pos, unsigned int *count, | |
283 | const void **kbuf, | |
284 | const void __user **ubuf, void *data, | |
285 | const int start_pos, const int end_pos) | |
286 | { | |
287 | if (*count == 0) | |
288 | return 0; | |
289 | BUG_ON(*pos < start_pos); | |
290 | if (end_pos < 0 || *pos < end_pos) { | |
291 | unsigned int copy = (end_pos < 0 ? *count | |
292 | : min(*count, end_pos - *pos)); | |
293 | data += *pos - start_pos; | |
294 | if (*kbuf) { | |
295 | memcpy(data, *kbuf, copy); | |
296 | *kbuf += copy; | |
297 | } else if (__copy_from_user(data, *ubuf, copy)) | |
298 | return -EFAULT; | |
299 | else | |
300 | *ubuf += copy; | |
301 | *pos += copy; | |
302 | *count -= copy; | |
303 | } | |
304 | return 0; | |
305 | } | |
306 | ||
307 | /* | |
308 | * These two parallel the two above, but for portions of a regset layout | |
309 | * that always read as all-zero or for which writes are ignored. | |
310 | */ | |
311 | static inline int user_regset_copyout_zero(unsigned int *pos, | |
312 | unsigned int *count, | |
313 | void **kbuf, void __user **ubuf, | |
314 | const int start_pos, | |
315 | const int end_pos) | |
316 | { | |
317 | if (*count == 0) | |
318 | return 0; | |
319 | BUG_ON(*pos < start_pos); | |
320 | if (end_pos < 0 || *pos < end_pos) { | |
321 | unsigned int copy = (end_pos < 0 ? *count | |
322 | : min(*count, end_pos - *pos)); | |
323 | if (*kbuf) { | |
324 | memset(*kbuf, 0, copy); | |
325 | *kbuf += copy; | |
326 | } else if (__clear_user(*ubuf, copy)) | |
327 | return -EFAULT; | |
328 | else | |
329 | *ubuf += copy; | |
330 | *pos += copy; | |
331 | *count -= copy; | |
332 | } | |
333 | return 0; | |
334 | } | |
335 | ||
336 | static inline int user_regset_copyin_ignore(unsigned int *pos, | |
337 | unsigned int *count, | |
338 | const void **kbuf, | |
339 | const void __user **ubuf, | |
340 | const int start_pos, | |
341 | const int end_pos) | |
342 | { | |
343 | if (*count == 0) | |
344 | return 0; | |
345 | BUG_ON(*pos < start_pos); | |
346 | if (end_pos < 0 || *pos < end_pos) { | |
347 | unsigned int copy = (end_pos < 0 ? *count | |
348 | : min(*count, end_pos - *pos)); | |
349 | if (*kbuf) | |
350 | *kbuf += copy; | |
351 | else | |
352 | *ubuf += copy; | |
353 | *pos += copy; | |
354 | *count -= copy; | |
355 | } | |
356 | return 0; | |
357 | } | |
358 | ||
5bde4d18 RM |
359 | /** |
360 | * copy_regset_to_user - fetch a thread's user_regset data into user memory | |
361 | * @target: thread to be examined | |
362 | * @view: &struct user_regset_view describing user thread machine state | |
363 | * @setno: index in @view->regsets | |
364 | * @offset: offset into the regset data, in bytes | |
365 | * @size: amount of data to copy, in bytes | |
366 | * @data: user-mode pointer to copy into | |
367 | */ | |
368 | static inline int copy_regset_to_user(struct task_struct *target, | |
369 | const struct user_regset_view *view, | |
370 | unsigned int setno, | |
371 | unsigned int offset, unsigned int size, | |
372 | void __user *data) | |
373 | { | |
374 | const struct user_regset *regset = &view->regsets[setno]; | |
375 | ||
c8e25258 PA |
376 | if (!regset->get) |
377 | return -EOPNOTSUPP; | |
378 | ||
5bde4d18 | 379 | if (!access_ok(VERIFY_WRITE, data, size)) |
5189fa19 | 380 | return -EFAULT; |
5bde4d18 RM |
381 | |
382 | return regset->get(target, regset, offset, size, NULL, data); | |
383 | } | |
384 | ||
385 | /** | |
386 | * copy_regset_from_user - store into thread's user_regset data from user memory | |
387 | * @target: thread to be examined | |
388 | * @view: &struct user_regset_view describing user thread machine state | |
389 | * @setno: index in @view->regsets | |
390 | * @offset: offset into the regset data, in bytes | |
391 | * @size: amount of data to copy, in bytes | |
392 | * @data: user-mode pointer to copy from | |
393 | */ | |
394 | static inline int copy_regset_from_user(struct task_struct *target, | |
395 | const struct user_regset_view *view, | |
396 | unsigned int setno, | |
397 | unsigned int offset, unsigned int size, | |
398 | const void __user *data) | |
399 | { | |
400 | const struct user_regset *regset = &view->regsets[setno]; | |
401 | ||
c8e25258 PA |
402 | if (!regset->set) |
403 | return -EOPNOTSUPP; | |
404 | ||
5bde4d18 | 405 | if (!access_ok(VERIFY_READ, data, size)) |
5189fa19 | 406 | return -EFAULT; |
5bde4d18 RM |
407 | |
408 | return regset->set(target, regset, offset, size, NULL, data); | |
409 | } | |
410 | ||
27e64b4b DM |
411 | /** |
412 | * regset_size - determine the current size of a regset | |
413 | * @target: thread to be examined | |
414 | * @regset: regset to be examined | |
415 | * | |
416 | * Note that the returned size is valid only until the next time | |
417 | * (if any) @regset is modified for @target. | |
418 | */ | |
419 | static inline unsigned int regset_size(struct task_struct *target, | |
420 | const struct user_regset *regset) | |
421 | { | |
422 | if (!regset->get_size) | |
423 | return regset->n * regset->size; | |
424 | else | |
425 | return regset->get_size(target, regset); | |
426 | } | |
bae3f7c3 | 427 | |
bdf88217 | 428 | #endif /* <linux/regset.h> */ |