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