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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>
187f1882 18#include <linux/bug.h>
bae3f7c3 19#include <linux/uaccess.h>
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20struct task_struct;
21struct 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 */
39typedef 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 */
58typedef 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 */
79typedef 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 */
105typedef 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 */
154struct 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 */
184struct 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 */
205const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);
206
207
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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
220static 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
245static 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 */
274static 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
299static 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
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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 */
331static 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
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339 if (!regset->get)
340 return -EOPNOTSUPP;
341
5bde4d18 342 if (!access_ok(VERIFY_WRITE, data, size))
5189fa19 343 return -EFAULT;
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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 */
357static 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
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365 if (!regset->set)
366 return -EOPNOTSUPP;
367
5bde4d18 368 if (!access_ok(VERIFY_READ, data, size))
5189fa19 369 return -EFAULT;
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370
371 return regset->set(target, regset, offset, size, NULL, data);
372}
373
bae3f7c3 374
bdf88217 375#endif /* <linux/regset.h> */