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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> |
18 | #include <linux/bug.h> |
19 | #include <linux/uaccess.h> |
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 | |
109 | /** |
110 | * struct user_regset - accessible thread CPU state |
111 | * @n: Number of slots (registers). |
112 | * @size: Size in bytes of a slot (register). |
113 | * @align: Required alignment, in bytes. |
114 | * @bias: Bias from natural indexing. |
115 | * @core_note_type: ELF note @n_type value used in core dumps. |
116 | * @get: Function to fetch values. |
117 | * @set: Function to store values. |
118 | * @active: Function to report if regset is active, or %NULL. |
119 | * @writeback: Function to write data back to user memory, or %NULL. |
120 | * |
121 | * This data structure describes a machine resource we call a register set. |
122 | * This is part of the state of an individual thread, not necessarily |
123 | * actual CPU registers per se. A register set consists of a number of |
124 | * similar slots, given by @n. Each slot is @size bytes, and aligned to |
125 | * @align bytes (which is at least @size). |
126 | * |
127 | * These functions must be called only on the current thread or on a |
128 | * thread that is in %TASK_STOPPED or %TASK_TRACED state, that we are |
129 | * guaranteed will not be woken up and return to user mode, and that we |
130 | * have called wait_task_inactive() on. (The target thread always might |
131 | * wake up for SIGKILL while these functions are working, in which case |
132 | * that thread's user_regset state might be scrambled.) |
133 | * |
134 | * The @pos argument must be aligned according to @align; the @count |
135 | * argument must be a multiple of @size. These functions are not |
136 | * responsible for checking for invalid arguments. |
137 | * |
138 | * When there is a natural value to use as an index, @bias gives the |
139 | * difference between the natural index and the slot index for the |
140 | * register set. For example, x86 GDT segment descriptors form a regset; |
141 | * the segment selector produces a natural index, but only a subset of |
142 | * that index space is available as a regset (the TLS slots); subtracting |
143 | * @bias from a segment selector index value computes the regset slot. |
144 | * |
145 | * If nonzero, @core_note_type gives the n_type field (NT_* value) |
146 | * of the core file note in which this regset's data appears. |
147 | * NT_PRSTATUS is a special case in that the regset data starts at |
148 | * offsetof(struct elf_prstatus, pr_reg) into the note data; that is |
149 | * part of the per-machine ELF formats userland knows about. In |
150 | * other cases, the core file note contains exactly the whole regset |
151 | * (@n * @size) and nothing else. The core file note is normally |
152 | * omitted when there is an @active function and it returns zero. |
153 | */ |
154 | struct user_regset { |
155 | user_regset_get_fn *get; |
156 | user_regset_set_fn *set; |
157 | user_regset_active_fn *active; |
158 | user_regset_writeback_fn *writeback; |
159 | unsigned int n; |
160 | unsigned int size; |
161 | unsigned int align; |
162 | unsigned int bias; |
163 | unsigned int core_note_type; |
164 | }; |
165 | |
166 | /** |
167 | * struct user_regset_view - available regsets |
168 | * @name: Identifier, e.g. UTS_MACHINE string. |
169 | * @regsets: Array of @n regsets available in this view. |
170 | * @n: Number of elements in @regsets. |
171 | * @e_machine: ELF header @e_machine %EM_* value written in core dumps. |
172 | * @e_flags: ELF header @e_flags value written in core dumps. |
173 | * @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps. |
174 | * |
175 | * A regset view is a collection of regsets (&struct user_regset, |
176 | * above). This describes all the state of a thread that can be seen |
177 | * from a given architecture/ABI environment. More than one view might |
178 | * refer to the same &struct user_regset, or more than one regset |
179 | * might refer to the same machine-specific state in the thread. For |
180 | * example, a 32-bit thread's state could be examined from the 32-bit |
181 | * view or from the 64-bit view. Either method reaches the same thread |
182 | * register state, doing appropriate widening or truncation. |
183 | */ |
184 | struct user_regset_view { |
185 | const char *name; |
186 | const struct user_regset *regsets; |
187 | unsigned int n; |
188 | u32 e_flags; |
189 | u16 e_machine; |
190 | u8 ei_osabi; |
191 | }; |
192 | |
193 | /* |
194 | * This is documented here rather than at the definition sites because its |
195 | * implementation is machine-dependent but its interface is universal. |
196 | */ |
197 | /** |
198 | * task_user_regset_view - Return the process's native regset view. |
199 | * @tsk: a thread of the process in question |
200 | * |
201 | * Return the &struct user_regset_view that is native for the given process. |
202 | * For example, what it would access when it called ptrace(). |
203 | * Throughout the life of the process, this only changes at exec. |
204 | */ |
205 | const struct user_regset_view *task_user_regset_view(struct task_struct *tsk); |
206 | |
207 | |
208 | /* |
209 | * These are helpers for writing regset get/set functions in arch code. |
210 | * Because @start_pos and @end_pos are always compile-time constants, |
211 | * these are inlined into very little code though they look large. |
212 | * |
213 | * Use one or more calls sequentially for each chunk of regset data stored |
214 | * contiguously in memory. Call with constants for @start_pos and @end_pos, |
215 | * giving the range of byte positions in the regset that data corresponds |
216 | * to; @end_pos can be -1 if this chunk is at the end of the regset layout. |
217 | * Each call updates the arguments to point past its chunk. |
218 | */ |
219 | |
220 | static inline int user_regset_copyout(unsigned int *pos, unsigned int *count, |
221 | void **kbuf, |
222 | void __user **ubuf, const void *data, |
223 | const int start_pos, const int end_pos) |
224 | { |
225 | if (*count == 0) |
226 | return 0; |
227 | BUG_ON(*pos < start_pos); |
228 | if (end_pos < 0 || *pos < end_pos) { |
229 | unsigned int copy = (end_pos < 0 ? *count |
230 | : min(*count, end_pos - *pos)); |
231 | data += *pos - start_pos; |
232 | if (*kbuf) { |
233 | memcpy(*kbuf, data, copy); |
234 | *kbuf += copy; |
235 | } else if (__copy_to_user(*ubuf, data, copy)) |
236 | return -EFAULT; |
237 | else |
238 | *ubuf += copy; |
239 | *pos += copy; |
240 | *count -= copy; |
241 | } |
242 | return 0; |
243 | } |
244 | |
245 | static inline int user_regset_copyin(unsigned int *pos, unsigned int *count, |
246 | const void **kbuf, |
247 | const void __user **ubuf, void *data, |
248 | const int start_pos, const int end_pos) |
249 | { |
250 | if (*count == 0) |
251 | return 0; |
252 | BUG_ON(*pos < start_pos); |
253 | if (end_pos < 0 || *pos < end_pos) { |
254 | unsigned int copy = (end_pos < 0 ? *count |
255 | : min(*count, end_pos - *pos)); |
256 | data += *pos - start_pos; |
257 | if (*kbuf) { |
258 | memcpy(data, *kbuf, copy); |
259 | *kbuf += copy; |
260 | } else if (__copy_from_user(data, *ubuf, copy)) |
261 | return -EFAULT; |
262 | else |
263 | *ubuf += copy; |
264 | *pos += copy; |
265 | *count -= copy; |
266 | } |
267 | return 0; |
268 | } |
269 | |
270 | /* |
271 | * These two parallel the two above, but for portions of a regset layout |
272 | * that always read as all-zero or for which writes are ignored. |
273 | */ |
274 | static inline int user_regset_copyout_zero(unsigned int *pos, |
275 | unsigned int *count, |
276 | void **kbuf, void __user **ubuf, |
277 | const int start_pos, |
278 | const int end_pos) |
279 | { |
280 | if (*count == 0) |
281 | return 0; |
282 | BUG_ON(*pos < start_pos); |
283 | if (end_pos < 0 || *pos < end_pos) { |
284 | unsigned int copy = (end_pos < 0 ? *count |
285 | : min(*count, end_pos - *pos)); |
286 | if (*kbuf) { |
287 | memset(*kbuf, 0, copy); |
288 | *kbuf += copy; |
289 | } else if (__clear_user(*ubuf, copy)) |
290 | return -EFAULT; |
291 | else |
292 | *ubuf += copy; |
293 | *pos += copy; |
294 | *count -= copy; |
295 | } |
296 | return 0; |
297 | } |
298 | |
299 | static inline int user_regset_copyin_ignore(unsigned int *pos, |
300 | unsigned int *count, |
301 | const void **kbuf, |
302 | const void __user **ubuf, |
303 | const int start_pos, |
304 | const int end_pos) |
305 | { |
306 | if (*count == 0) |
307 | return 0; |
308 | BUG_ON(*pos < start_pos); |
309 | if (end_pos < 0 || *pos < end_pos) { |
310 | unsigned int copy = (end_pos < 0 ? *count |
311 | : min(*count, end_pos - *pos)); |
312 | if (*kbuf) |
313 | *kbuf += copy; |
314 | else |
315 | *ubuf += copy; |
316 | *pos += copy; |
317 | *count -= copy; |
318 | } |
319 | return 0; |
320 | } |
321 | |
322 | /** |
323 | * copy_regset_to_user - fetch a thread's user_regset data into user memory |
324 | * @target: thread to be examined |
325 | * @view: &struct user_regset_view describing user thread machine state |
326 | * @setno: index in @view->regsets |
327 | * @offset: offset into the regset data, in bytes |
328 | * @size: amount of data to copy, in bytes |
329 | * @data: user-mode pointer to copy into |
330 | */ |
331 | static inline int copy_regset_to_user(struct task_struct *target, |
332 | const struct user_regset_view *view, |
333 | unsigned int setno, |
334 | unsigned int offset, unsigned int size, |
335 | void __user *data) |
336 | { |
337 | const struct user_regset *regset = &view->regsets[setno]; |
338 | |
339 | if (!regset->get) |
340 | return -EOPNOTSUPP; |
341 | |
342 | if (!access_ok(VERIFY_WRITE, data, size)) |
343 | return -EFAULT; |
344 | |
345 | return regset->get(target, regset, offset, size, NULL, data); |
346 | } |
347 | |
348 | /** |
349 | * copy_regset_from_user - store into thread's user_regset data from user memory |
350 | * @target: thread to be examined |
351 | * @view: &struct user_regset_view describing user thread machine state |
352 | * @setno: index in @view->regsets |
353 | * @offset: offset into the regset data, in bytes |
354 | * @size: amount of data to copy, in bytes |
355 | * @data: user-mode pointer to copy from |
356 | */ |
357 | static inline int copy_regset_from_user(struct task_struct *target, |
358 | const struct user_regset_view *view, |
359 | unsigned int setno, |
360 | unsigned int offset, unsigned int size, |
361 | const void __user *data) |
362 | { |
363 | const struct user_regset *regset = &view->regsets[setno]; |
364 | |
365 | if (!regset->set) |
366 | return -EOPNOTSUPP; |
367 | |
368 | if (!access_ok(VERIFY_READ, data, size)) |
369 | return -EFAULT; |
370 | |
371 | return regset->set(target, regset, offset, size, NULL, data); |
372 | } |
373 | |
374 | |
375 | #endif /* <linux/regset.h> */ |
376 |
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