1#include <linux/kernel.h>
2#include <linux/errno.h>
3#include <linux/sched.h>
4#include <linux/user.h>
5#include <linux/regset.h>
6#include <linux/syscalls.h>
7
8#include <asm/uaccess.h>
9#include <asm/desc.h>
10#include <asm/ldt.h>
11#include <asm/processor.h>
12#include <asm/proto.h>
13
14#include "tls.h"
15
16/*
17 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
18 */
19static int get_free_idx(void)
20{
21	struct thread_struct *t = &current->thread;
22	int idx;
23
24	for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
25		if (desc_empty(&t->tls_array[idx]))
26			return idx + GDT_ENTRY_TLS_MIN;
27	return -ESRCH;
28}
29
30static void set_tls_desc(struct task_struct *p, int idx,
31			 const struct user_desc *info, int n)
32{
33	struct thread_struct *t = &p->thread;
34	struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN];
35	int cpu;
36
37	/*
38	 * We must not get preempted while modifying the TLS.
39	 */
40	cpu = get_cpu();
41
42	while (n-- > 0) {
43		if (LDT_empty(info))
44			desc->a = desc->b = 0;
45		else
46			fill_ldt(desc, info);
47		++info;
48		++desc;
49	}
50
51	if (t == &current->thread)
52		load_TLS(t, cpu);
53
54	put_cpu();
55}
56
57/*
58 * Set a given TLS descriptor:
59 */
60int do_set_thread_area(struct task_struct *p, int idx,
61		       struct user_desc __user *u_info,
62		       int can_allocate)
63{
64	struct user_desc info;
65
66	if (copy_from_user(&info, u_info, sizeof(info)))
67		return -EFAULT;
68
69	if (idx == -1)
70		idx = info.entry_number;
71
72	/*
73	 * index -1 means the kernel should try to find and
74	 * allocate an empty descriptor:
75	 */
76	if (idx == -1 && can_allocate) {
77		idx = get_free_idx();
78		if (idx < 0)
79			return idx;
80		if (put_user(idx, &u_info->entry_number))
81			return -EFAULT;
82	}
83
84	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
85		return -EINVAL;
86
87	set_tls_desc(p, idx, &info, 1);
88
89	return 0;
90}
91
92SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
93{
94	return do_set_thread_area(current, -1, u_info, 1);
95}
96
97
98/*
99 * Get the current Thread-Local Storage area:
100 */
101
102static void fill_user_desc(struct user_desc *info, int idx,
103			   const struct desc_struct *desc)
104
105{
106	memset(info, 0, sizeof(*info));
107	info->entry_number = idx;
108	info->base_addr = get_desc_base(desc);
109	info->limit = get_desc_limit(desc);
110	info->seg_32bit = desc->d;
111	info->contents = desc->type >> 2;
112	info->read_exec_only = !(desc->type & 2);
113	info->limit_in_pages = desc->g;
114	info->seg_not_present = !desc->p;
115	info->useable = desc->avl;
116#ifdef CONFIG_X86_64
117	info->lm = desc->l;
118#endif
119}
120
121int do_get_thread_area(struct task_struct *p, int idx,
122		       struct user_desc __user *u_info)
123{
124	struct user_desc info;
125
126	if (idx == -1 && get_user(idx, &u_info->entry_number))
127		return -EFAULT;
128
129	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
130		return -EINVAL;
131
132	fill_user_desc(&info, idx,
133		       &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]);
134
135	if (copy_to_user(u_info, &info, sizeof(info)))
136		return -EFAULT;
137	return 0;
138}
139
140SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
141{
142	return do_get_thread_area(current, -1, u_info);
143}
144
145int regset_tls_active(struct task_struct *target,
146		      const struct user_regset *regset)
147{
148	struct thread_struct *t = &target->thread;
149	int n = GDT_ENTRY_TLS_ENTRIES;
150	while (n > 0 && desc_empty(&t->tls_array[n - 1]))
151		--n;
152	return n;
153}
154
155int regset_tls_get(struct task_struct *target, const struct user_regset *regset,
156		   unsigned int pos, unsigned int count,
157		   void *kbuf, void __user *ubuf)
158{
159	const struct desc_struct *tls;
160
161	if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
162	    (pos % sizeof(struct user_desc)) != 0 ||
163	    (count % sizeof(struct user_desc)) != 0)
164		return -EINVAL;
165
166	pos /= sizeof(struct user_desc);
167	count /= sizeof(struct user_desc);
168
169	tls = &target->thread.tls_array[pos];
170
171	if (kbuf) {
172		struct user_desc *info = kbuf;
173		while (count-- > 0)
174			fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++,
175				       tls++);
176	} else {
177		struct user_desc __user *u_info = ubuf;
178		while (count-- > 0) {
179			struct user_desc info;
180			fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++);
181			if (__copy_to_user(u_info++, &info, sizeof(info)))
182				return -EFAULT;
183		}
184	}
185
186	return 0;
187}
188
189int regset_tls_set(struct task_struct *target, const struct user_regset *regset,
190		   unsigned int pos, unsigned int count,
191		   const void *kbuf, const void __user *ubuf)
192{
193	struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES];
194	const struct user_desc *info;
195
196	if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
197	    (pos % sizeof(struct user_desc)) != 0 ||
198	    (count % sizeof(struct user_desc)) != 0)
199		return -EINVAL;
200
201	if (kbuf)
202		info = kbuf;
203	else if (__copy_from_user(infobuf, ubuf, count))
204		return -EFAULT;
205	else
206		info = infobuf;
207
208	set_tls_desc(target,
209		     GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)),
210		     info, count / sizeof(struct user_desc));
211
212	return 0;
213}
214