summaryrefslogtreecommitdiffstats
path: root/arch/x86/ia32/tls32.c
blob: 1cc4340de3ca4997b9966e8a5065f21b42e8c6c2 (plain)
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
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/user.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>

/*
 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
 */
static int get_free_idx(void)
{
	struct thread_struct *t = &current->thread;
	int idx;

	for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
		if (desc_empty((struct n_desc_struct *)(t->tls_array) + idx))
			return idx + GDT_ENTRY_TLS_MIN;
	return -ESRCH;
}

/*
 * Set a given TLS descriptor:
 * When you want addresses > 32bit use arch_prctl() 
 */
int do_set_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
{
	struct user_desc info;
	struct n_desc_struct *desc;
	int cpu, idx;

	if (copy_from_user(&info, u_info, sizeof(info)))
		return -EFAULT;

	idx = info.entry_number;

	/*
	 * index -1 means the kernel should try to find and
	 * allocate an empty descriptor:
	 */
	if (idx == -1) {
		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;

	desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;

	/*
	 * We must not get preempted while modifying the TLS.
	 */
	cpu = get_cpu();

	if (LDT_empty(&info)) {
		desc->a = 0;
		desc->b = 0;
	} else {
		desc->a = LDT_entry_a(&info);
		desc->b = LDT_entry_b(&info);
	}
	if (t == &current->thread)
		load_TLS(t, cpu);

	put_cpu();
	return 0;
}

asmlinkage long sys32_set_thread_area(struct user_desc __user *u_info)
{ 
	return do_set_thread_area(&current->thread, u_info); 
} 


/*
 * Get the current Thread-Local Storage area:
 */

#define GET_BASE(desc) ( \
	(((desc)->a >> 16) & 0x0000ffff) | \
	(((desc)->b << 16) & 0x00ff0000) | \
	( (desc)->b        & 0xff000000)   )

#define GET_LIMIT(desc) ( \
	((desc)->a & 0x0ffff) | \
	 ((desc)->b & 0xf0000) )
	
#define GET_32BIT(desc)		(((desc)->b >> 22) & 1)
#define GET_CONTENTS(desc)	(((desc)->b >> 10) & 3)
#define GET_WRITABLE(desc)	(((desc)->b >>  9) & 1)
#define GET_LIMIT_PAGES(desc)	(((desc)->b >> 23) & 1)
#define GET_PRESENT(desc)	(((desc)->b >> 15) & 1)
#define GET_USEABLE(desc)	(((desc)->b >> 20) & 1)
#define GET_LONGMODE(desc)	(((desc)->b >> 21) & 1)

int do_get_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
{
	struct user_desc info;
	struct n_desc_struct *desc;
	int idx;

	if (get_user(idx, &u_info->entry_number))
		return -EFAULT;
	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
		return -EINVAL;

	desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;

	memset(&info, 0, sizeof(struct user_desc));
	info.entry_number = idx;
	info.base_addr = GET_BASE(desc);
	info.limit = GET_LIMIT(desc);
	info.seg_32bit = GET_32BIT(desc);
	info.contents = GET_CONTENTS(desc);
	info.read_exec_only = !GET_WRITABLE(desc);
	info.limit_in_pages = GET_LIMIT_PAGES(desc);
	info.seg_not_present = !GET_PRESENT(desc);
	info.useable = GET_USEABLE(desc);
	info.lm = GET_LONGMODE(desc);

	if (copy_to_user(u_info, &info, sizeof(info)))
		return -EFAULT;
	return 0;
}

asmlinkage long sys32_get_thread_area(struct user_desc __user *u_info)
{
	return do_get_thread_area(&current->thread, u_info);
} 


int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs)
{
	struct n_desc_struct *desc;
	struct user_desc info;
	struct user_desc __user *cp;
	int idx;
	
	cp = (void __user *)childregs->rsi;
	if (copy_from_user(&info, cp, sizeof(info)))
		return -EFAULT;
	if (LDT_empty(&info))
		return -EINVAL;
	
	idx = info.entry_number;
	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
		return -EINVAL;
	
	desc = (struct n_desc_struct *)(p->thread.tls_array) + idx - GDT_ENTRY_TLS_MIN;
	desc->a = LDT_entry_a(&info);
	desc->b = LDT_entry_b(&info);

	return 0;
}