1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/export.h>
3#include <linux/slab.h>
4#include <linux/regset.h>
5
6static 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 = kzalloc(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		kfree(to_free);
27		return res;
28	}
29	*data = p;
30	return size - res;
31}
32
33int 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}
40EXPORT_SYMBOL(regset_get);
41
42int 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}
50EXPORT_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 */
61int 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	kfree(buf);
75	return ret;
76}
77