1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* |
3 | * User-mode machine state access |
4 | * |
5 | * Copyright (C) 2007 Red Hat, Inc. All rights reserved. |
6 | * |
7 | * Red Hat Author: Roland McGrath. |
8 | */ |
9 | |
10 | #ifndef _LINUX_REGSET_H |
11 | #define _LINUX_REGSET_H 1 |
12 | |
13 | #include <linux/compiler.h> |
14 | #include <linux/types.h> |
15 | #include <linux/bug.h> |
16 | #include <linux/uaccess.h> |
17 | struct task_struct; |
18 | struct user_regset; |
19 | |
20 | struct membuf { |
21 | void *p; |
22 | size_t left; |
23 | }; |
24 | |
25 | static inline int membuf_zero(struct membuf *s, size_t size) |
26 | { |
27 | if (s->left) { |
28 | if (size > s->left) |
29 | size = s->left; |
30 | memset(s->p, 0, size); |
31 | s->p += size; |
32 | s->left -= size; |
33 | } |
34 | return s->left; |
35 | } |
36 | |
37 | static inline int membuf_write(struct membuf *s, const void *v, size_t size) |
38 | { |
39 | if (s->left) { |
40 | if (size > s->left) |
41 | size = s->left; |
42 | memcpy(s->p, v, size); |
43 | s->p += size; |
44 | s->left -= size; |
45 | } |
46 | return s->left; |
47 | } |
48 | |
49 | static inline struct membuf membuf_at(const struct membuf *s, size_t offs) |
50 | { |
51 | struct membuf n = *s; |
52 | |
53 | if (offs > n.left) |
54 | offs = n.left; |
55 | n.p += offs; |
56 | n.left -= offs; |
57 | |
58 | return n; |
59 | } |
60 | |
61 | /* current s->p must be aligned for v; v must be a scalar */ |
62 | #define membuf_store(s, v) \ |
63 | ({ \ |
64 | struct membuf *__s = (s); \ |
65 | if (__s->left) { \ |
66 | typeof(v) __v = (v); \ |
67 | size_t __size = sizeof(__v); \ |
68 | if (unlikely(__size > __s->left)) { \ |
69 | __size = __s->left; \ |
70 | memcpy(__s->p, &__v, __size); \ |
71 | } else { \ |
72 | *(typeof(__v + 0) *)__s->p = __v; \ |
73 | } \ |
74 | __s->p += __size; \ |
75 | __s->left -= __size; \ |
76 | } \ |
77 | __s->left;}) |
78 | |
79 | /** |
80 | * user_regset_active_fn - type of @active function in &struct user_regset |
81 | * @target: thread being examined |
82 | * @regset: regset being examined |
83 | * |
84 | * Return -%ENODEV if not available on the hardware found. |
85 | * Return %0 if no interesting state in this thread. |
86 | * Return >%0 number of @size units of interesting state. |
87 | * Any get call fetching state beyond that number will |
88 | * see the default initialization state for this data, |
89 | * so a caller that knows what the default state is need |
90 | * not copy it all out. |
91 | * This call is optional; the pointer is %NULL if there |
92 | * is no inexpensive check to yield a value < @n. |
93 | */ |
94 | typedef int user_regset_active_fn(struct task_struct *target, |
95 | const struct user_regset *regset); |
96 | |
97 | typedef int user_regset_get2_fn(struct task_struct *target, |
98 | const struct user_regset *regset, |
99 | struct membuf to); |
100 | |
101 | /** |
102 | * user_regset_set_fn - type of @set function in &struct user_regset |
103 | * @target: thread being examined |
104 | * @regset: regset being examined |
105 | * @pos: offset into the regset data to access, in bytes |
106 | * @count: amount of data to copy, in bytes |
107 | * @kbuf: if not %NULL, a kernel-space pointer to copy from |
108 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy from |
109 | * |
110 | * Store register values. Return %0 on success; -%EIO or -%ENODEV |
111 | * are usual failure returns. The @pos and @count values are in |
112 | * bytes, but must be properly aligned. If @kbuf is non-null, that |
113 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then |
114 | * ubuf gives a userland pointer to access directly, and an -%EFAULT |
115 | * return value is possible. |
116 | */ |
117 | typedef int user_regset_set_fn(struct task_struct *target, |
118 | const struct user_regset *regset, |
119 | unsigned int pos, unsigned int count, |
120 | const void *kbuf, const void __user *ubuf); |
121 | |
122 | /** |
123 | * user_regset_writeback_fn - type of @writeback function in &struct user_regset |
124 | * @target: thread being examined |
125 | * @regset: regset being examined |
126 | * @immediate: zero if writeback at completion of next context switch is OK |
127 | * |
128 | * This call is optional; usually the pointer is %NULL. When |
129 | * provided, there is some user memory associated with this regset's |
130 | * hardware, such as memory backing cached register data on register |
131 | * window machines; the regset's data controls what user memory is |
132 | * used (e.g. via the stack pointer value). |
133 | * |
134 | * Write register data back to user memory. If the @immediate flag |
135 | * is nonzero, it must be written to the user memory so uaccess or |
136 | * access_process_vm() can see it when this call returns; if zero, |
137 | * then it must be written back by the time the task completes a |
138 | * context switch (as synchronized with wait_task_inactive()). |
139 | * Return %0 on success or if there was nothing to do, -%EFAULT for |
140 | * a memory problem (bad stack pointer or whatever), or -%EIO for a |
141 | * hardware problem. |
142 | */ |
143 | typedef int user_regset_writeback_fn(struct task_struct *target, |
144 | const struct user_regset *regset, |
145 | int immediate); |
146 | |
147 | /** |
148 | * struct user_regset - accessible thread CPU state |
149 | * @n: Number of slots (registers). |
150 | * @size: Size in bytes of a slot (register). |
151 | * @align: Required alignment, in bytes. |
152 | * @bias: Bias from natural indexing. |
153 | * @core_note_type: ELF note @n_type value used in core dumps. |
154 | * @get: Function to fetch values. |
155 | * @set: Function to store values. |
156 | * @active: Function to report if regset is active, or %NULL. |
157 | * @writeback: Function to write data back to user memory, or %NULL. |
158 | * |
159 | * This data structure describes a machine resource we call a register set. |
160 | * This is part of the state of an individual thread, not necessarily |
161 | * actual CPU registers per se. A register set consists of a number of |
162 | * similar slots, given by @n. Each slot is @size bytes, and aligned to |
163 | * @align bytes (which is at least @size). For dynamically-sized |
164 | * regsets, @n must contain the maximum possible number of slots for the |
165 | * regset. |
166 | * |
167 | * For backward compatibility, the @get and @set methods must pad to, or |
168 | * accept, @n * @size bytes, even if the current regset size is smaller. |
169 | * The precise semantics of these operations depend on the regset being |
170 | * accessed. |
171 | * |
172 | * The functions to which &struct user_regset members point must be |
173 | * called only on the current thread or on a thread that is in |
174 | * %TASK_STOPPED or %TASK_TRACED state, that we are guaranteed will not |
175 | * be woken up and return to user mode, and that we have called |
176 | * wait_task_inactive() on. (The target thread always might wake up for |
177 | * SIGKILL while these functions are working, in which case that |
178 | * thread's user_regset state might be scrambled.) |
179 | * |
180 | * The @pos argument must be aligned according to @align; the @count |
181 | * argument must be a multiple of @size. These functions are not |
182 | * responsible for checking for invalid arguments. |
183 | * |
184 | * When there is a natural value to use as an index, @bias gives the |
185 | * difference between the natural index and the slot index for the |
186 | * register set. For example, x86 GDT segment descriptors form a regset; |
187 | * the segment selector produces a natural index, but only a subset of |
188 | * that index space is available as a regset (the TLS slots); subtracting |
189 | * @bias from a segment selector index value computes the regset slot. |
190 | * |
191 | * If nonzero, @core_note_type gives the n_type field (NT_* value) |
192 | * of the core file note in which this regset's data appears. |
193 | * NT_PRSTATUS is a special case in that the regset data starts at |
194 | * offsetof(struct elf_prstatus, pr_reg) into the note data; that is |
195 | * part of the per-machine ELF formats userland knows about. In |
196 | * other cases, the core file note contains exactly the whole regset |
197 | * (@n * @size) and nothing else. The core file note is normally |
198 | * omitted when there is an @active function and it returns zero. |
199 | */ |
200 | struct user_regset { |
201 | user_regset_get2_fn *regset_get; |
202 | user_regset_set_fn *set; |
203 | user_regset_active_fn *active; |
204 | user_regset_writeback_fn *writeback; |
205 | unsigned int n; |
206 | unsigned int size; |
207 | unsigned int align; |
208 | unsigned int bias; |
209 | unsigned int core_note_type; |
210 | }; |
211 | |
212 | /** |
213 | * struct user_regset_view - available regsets |
214 | * @name: Identifier, e.g. UTS_MACHINE string. |
215 | * @regsets: Array of @n regsets available in this view. |
216 | * @n: Number of elements in @regsets. |
217 | * @e_machine: ELF header @e_machine %EM_* value written in core dumps. |
218 | * @e_flags: ELF header @e_flags value written in core dumps. |
219 | * @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps. |
220 | * |
221 | * A regset view is a collection of regsets (&struct user_regset, |
222 | * above). This describes all the state of a thread that can be seen |
223 | * from a given architecture/ABI environment. More than one view might |
224 | * refer to the same &struct user_regset, or more than one regset |
225 | * might refer to the same machine-specific state in the thread. For |
226 | * example, a 32-bit thread's state could be examined from the 32-bit |
227 | * view or from the 64-bit view. Either method reaches the same thread |
228 | * register state, doing appropriate widening or truncation. |
229 | */ |
230 | struct user_regset_view { |
231 | const char *name; |
232 | const struct user_regset *regsets; |
233 | unsigned int n; |
234 | u32 e_flags; |
235 | u16 e_machine; |
236 | u8 ei_osabi; |
237 | }; |
238 | |
239 | /* |
240 | * This is documented here rather than at the definition sites because its |
241 | * implementation is machine-dependent but its interface is universal. |
242 | */ |
243 | /** |
244 | * task_user_regset_view - Return the process's native regset view. |
245 | * @tsk: a thread of the process in question |
246 | * |
247 | * Return the &struct user_regset_view that is native for the given process. |
248 | * For example, what it would access when it called ptrace(). |
249 | * Throughout the life of the process, this only changes at exec. |
250 | */ |
251 | const struct user_regset_view *task_user_regset_view(struct task_struct *tsk); |
252 | |
253 | static inline int user_regset_copyin(unsigned int *pos, unsigned int *count, |
254 | const void **kbuf, |
255 | const void __user **ubuf, void *data, |
256 | const int start_pos, const int end_pos) |
257 | { |
258 | if (*count == 0) |
259 | return 0; |
260 | BUG_ON(*pos < start_pos); |
261 | if (end_pos < 0 || *pos < end_pos) { |
262 | unsigned int copy = (end_pos < 0 ? *count |
263 | : min(*count, end_pos - *pos)); |
264 | data += *pos - start_pos; |
265 | if (*kbuf) { |
266 | memcpy(data, *kbuf, copy); |
267 | *kbuf += copy; |
268 | } else if (__copy_from_user(to: data, from: *ubuf, n: copy)) |
269 | return -EFAULT; |
270 | else |
271 | *ubuf += copy; |
272 | *pos += copy; |
273 | *count -= copy; |
274 | } |
275 | return 0; |
276 | } |
277 | |
278 | static inline void user_regset_copyin_ignore(unsigned int *pos, |
279 | unsigned int *count, |
280 | const void **kbuf, |
281 | const void __user **ubuf, |
282 | const int start_pos, |
283 | const int end_pos) |
284 | { |
285 | if (*count == 0) |
286 | return; |
287 | BUG_ON(*pos < start_pos); |
288 | if (end_pos < 0 || *pos < end_pos) { |
289 | unsigned int copy = (end_pos < 0 ? *count |
290 | : min(*count, end_pos - *pos)); |
291 | if (*kbuf) |
292 | *kbuf += copy; |
293 | else |
294 | *ubuf += copy; |
295 | *pos += copy; |
296 | *count -= copy; |
297 | } |
298 | } |
299 | |
300 | extern int regset_get(struct task_struct *target, |
301 | const struct user_regset *regset, |
302 | unsigned int size, void *data); |
303 | |
304 | extern int regset_get_alloc(struct task_struct *target, |
305 | const struct user_regset *regset, |
306 | unsigned int size, |
307 | void **data); |
308 | |
309 | extern int copy_regset_to_user(struct task_struct *target, |
310 | const struct user_regset_view *view, |
311 | unsigned int setno, unsigned int offset, |
312 | unsigned int size, void __user *data); |
313 | |
314 | /** |
315 | * copy_regset_from_user - store into thread's user_regset data from user memory |
316 | * @target: thread to be examined |
317 | * @view: &struct user_regset_view describing user thread machine state |
318 | * @setno: index in @view->regsets |
319 | * @offset: offset into the regset data, in bytes |
320 | * @size: amount of data to copy, in bytes |
321 | * @data: user-mode pointer to copy from |
322 | */ |
323 | static inline int copy_regset_from_user(struct task_struct *target, |
324 | const struct user_regset_view *view, |
325 | unsigned int setno, |
326 | unsigned int offset, unsigned int size, |
327 | const void __user *data) |
328 | { |
329 | const struct user_regset *regset = &view->regsets[setno]; |
330 | |
331 | if (!regset->set) |
332 | return -EOPNOTSUPP; |
333 | |
334 | if (!access_ok(data, size)) |
335 | return -EFAULT; |
336 | |
337 | return regset->set(target, regset, offset, size, NULL, data); |
338 | } |
339 | |
340 | #endif /* <linux/regset.h> */ |
341 | |