1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/export.h>
3 #include <linux/slab.h>
4 #include <linux/regset.h>
5
6 static int __regset_get(struct task_struct *target,
7 const struct user_regset *regset,
8 unsigned int size,
9 void **data)
10 {
11 void *p = *data, *to_free = NULL;
12 int res;
13
14 if (!regset->regset_get)
15 return -EOPNOTSUPP;
16 if (size > regset->n * regset->size)
17 size = regset->n * regset->size;
18 if (!p) {
19 to_free = p = kvzalloc(size, GFP_KERNEL);
20 if (!p)
21 return -ENOMEM;
22 }
23 res = regset->regset_get(target, regset,
24 (struct membuf){.p = p, .left = size});
25 if (res < 0) {
26 kvfree(to_free);
27 return res;
28 }
29 *data = p;
30 return size - res;
31 }
32
33 int regset_get(struct task_struct *target,
34 const struct user_regset *regset,
35 unsigned int size,
36 void *data)
37 {
38 return __regset_get(target, regset, size, &data);
39 }
40 EXPORT_SYMBOL(regset_get);
41
42 int regset_get_alloc(struct task_struct *target,
43 const struct user_regset *regset,
44 unsigned int size,
45 void **data)
46 {
47 *data = NULL;
48 return __regset_get(target, regset, size, data);
49 }
50 EXPORT_SYMBOL(regset_get_alloc);
51
52 /**
53 * copy_regset_to_user - fetch a thread's user_regset data into user memory
54 * @target: thread to be examined
55 * @view: &struct user_regset_view describing user thread machine state
56 * @setno: index in @view->regsets
57 * @offset: offset into the regset data, in bytes
58 * @size: amount of data to copy, in bytes
59 * @data: user-mode pointer to copy into
60 */
61 int copy_regset_to_user(struct task_struct *target,
62 const struct user_regset_view *view,
63 unsigned int setno,
64 unsigned int offset, unsigned int size,
65 void __user *data)
66 {
67 const struct user_regset *regset = &view->regsets[setno];
68 void *buf;
69 int ret;
70
71 ret = regset_get_alloc(target, regset, size, &buf);
72 if (ret > 0)
73 ret = copy_to_user(data, buf, ret) ? -EFAULT : 0;
74 kvfree(buf);
75 return ret;
76 }
77
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