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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 : 0 : const struct user_regset *regset = &view->regsets[setno];
338 : :
339 [ # # ]: 0 : if (!regset->get)
340 : : return -EOPNOTSUPP;
341 : :
342 [ # # ]: 0 : if (!access_ok(VERIFY_WRITE, data, size))
343 : : return -EFAULT;
344 : :
345 : 0 : 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 : 0 : const struct user_regset *regset = &view->regsets[setno];
364 : :
365 [ # # ]: 0 : if (!regset->set)
366 : : return -EOPNOTSUPP;
367 : :
368 [ # # ]: 0 : if (!access_ok(VERIFY_READ, data, size))
369 : : return -EFAULT;
370 : :
371 : 0 : return regset->set(target, regset, offset, size, NULL, data);
372 : : }
373 : :
374 : :
375 : : #endif /* <linux/regset.h> */
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