1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/user.h>
#include <linux/regset.h>
#include <asm/uaccess.h>
#include <asm/desc.h>
#include <asm/system.h>
#include <asm/ldt.h>
#include <asm/processor.h>
#include <asm/proto.h>
#include "tls.h"
/*
* sys_alloc_thread_area: get a yet unused TLS descriptor index.
*/
static int get_free_idx(void)
{
struct thread_struct *t = ¤t->thread;
int idx;
for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
if (desc_empty(&t->tls_array[idx]))
return idx + GDT_ENTRY_TLS_MIN;
return -ESRCH;
}
static void set_tls_desc(struct task_struct *p, int idx,
const struct user_desc *info, int n)
{
struct thread_struct *t = &p->thread;
struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN];
int cpu;
/*
* We must not get preempted while modifying the TLS.
*/
cpu = get_cpu();
while (n-- > 0) {
if (LDT_empty(info))
desc->a = desc->b = 0;
else
fill_ldt(desc, info);
++info;
++desc;
}
if (t == ¤t->thread)
load_TLS(t, cpu);
put_cpu();
}
/*
* Set a given TLS descriptor:
*/
int do_set_thread_area(struct task_struct *p, int idx,
struct user_desc __user *u_info,
int can_allocate)
{
struct user_desc info;
if (copy_from_user(&info, u_info, sizeof(info)))
return -EFAULT;
if (idx == -1)
idx = info.entry_number;
/*
* index -1 means the kernel should try to find and
* allocate an empty descriptor:
*/
if (idx == -1 && can_allocate) {
idx = get_free_idx();
if (idx < 0)
return idx;
if (put_user(idx, &u_info->entry_number))
return -EFAULT;
}
if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
return -EINVAL;
set_tls_desc(p, idx, &info, 1);
return 0;
}
asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
{
int ret = do_set_thread_area(current, -1, u_info, 1);
prevent_tail_call(ret);
return ret;
}
/*
* Get the current Thread-Local Storage area:
*/
static void fill_user_desc(struct user_desc *info, int idx,
const struct desc_struct *desc)
{
memset(info, 0, sizeof(*info));
info->entry_number = idx;
info->base_addr = get_desc_base(desc);
info->limit = get_desc_limit(desc);
info->seg_32bit = desc->d;
info->contents = desc->type >> 2;
info->read_exec_only = !(desc->type & 2);
info->limit_in_pages = desc->g;
info->seg_not_present = !desc->p;
info->useable = desc->avl;
#ifdef CONFIG_X86_64
info->lm = desc->l;
#endif
}
int do_get_thread_area(struct task_struct *p, int idx,
struct user_desc __user *u_info)
{
struct user_desc info;
if (idx == -1 && get_user(idx, &u_info->entry_number))
return -EFAULT;
if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
return -EINVAL;
fill_user_desc(&info, idx,
&p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]);
if (copy_to_user(u_info, &info, sizeof(info)))
return -EFAULT;
return 0;
}
asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
{
int ret = do_get_thread_area(current, -1, u_info);
prevent_tail_call(ret);
return ret;
}
int regset_tls_active(struct task_struct *target,
const struct user_regset *regset)
{
struct thread_struct *t = &target->thread;
int n = GDT_ENTRY_TLS_ENTRIES;
while (n > 0 && desc_empty(&t->tls_array[n - 1]))
--n;
return n;
}
int regset_tls_get(struct task_struct *target, const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
const struct desc_struct *tls;
if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
(pos % sizeof(struct user_desc)) != 0 ||
(count % sizeof(struct user_desc)) != 0)
return -EINVAL;
pos /= sizeof(struct user_desc);
count /= sizeof(struct user_desc);
tls = &target->thread.tls_array[pos];
if (kbuf) {
struct user_desc *info = kbuf;
while (count-- > 0)
fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++,
tls++);
} else {
struct user_desc __user *u_info = ubuf;
while (count-- > 0) {
struct user_desc info;
fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++);
if (__copy_to_user(u_info++, &info, sizeof(info)))
return -EFAULT;
}
}
return 0;
}
int regset_tls_set(struct task_struct *target, const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES];
const struct user_desc *info;
if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
(pos % sizeof(struct user_desc)) != 0 ||
(count % sizeof(struct user_desc)) != 0)
return -EINVAL;
if (kbuf)
info = kbuf;
else if (__copy_from_user(infobuf, ubuf, count))
return -EFAULT;
else
info = infobuf;
set_tls_desc(target,
GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)),
info, count / sizeof(struct user_desc));
return 0;
}
|
