Linux 3.8-rc7
[cris-mirror.git] / arch / x86 / kernel / tls.c
blob9d9d2f9e77a5a18e318a64915e17008e82aa0537
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>
7 #include <asm/uaccess.h>
8 #include <asm/desc.h>
9 #include <asm/ldt.h>
10 #include <asm/processor.h>
11 #include <asm/proto.h>
12 #include <asm/syscalls.h>
14 #include "tls.h"
17 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
19 static int get_free_idx(void)
21 struct thread_struct *t = &current->thread;
22 int idx;
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;
30 static void set_tls_desc(struct task_struct *p, int idx,
31 const struct user_desc *info, int n)
33 struct thread_struct *t = &p->thread;
34 struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN];
35 int cpu;
38 * We must not get preempted while modifying the TLS.
40 cpu = get_cpu();
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;
51 if (t == &current->thread)
52 load_TLS(t, cpu);
54 put_cpu();
58 * Set a given TLS descriptor:
60 int do_set_thread_area(struct task_struct *p, int idx,
61 struct user_desc __user *u_info,
62 int can_allocate)
64 struct user_desc info;
66 if (copy_from_user(&info, u_info, sizeof(info)))
67 return -EFAULT;
69 if (idx == -1)
70 idx = info.entry_number;
73 * index -1 means the kernel should try to find and
74 * allocate an empty descriptor:
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;
84 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
85 return -EINVAL;
87 set_tls_desc(p, idx, &info, 1);
89 return 0;
92 asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
94 int ret = do_set_thread_area(current, -1, u_info, 1);
95 asmlinkage_protect(1, ret, u_info);
96 return ret;
101 * Get the current Thread-Local Storage area:
104 static void fill_user_desc(struct user_desc *info, int idx,
105 const struct desc_struct *desc)
108 memset(info, 0, sizeof(*info));
109 info->entry_number = idx;
110 info->base_addr = get_desc_base(desc);
111 info->limit = get_desc_limit(desc);
112 info->seg_32bit = desc->d;
113 info->contents = desc->type >> 2;
114 info->read_exec_only = !(desc->type & 2);
115 info->limit_in_pages = desc->g;
116 info->seg_not_present = !desc->p;
117 info->useable = desc->avl;
118 #ifdef CONFIG_X86_64
119 info->lm = desc->l;
120 #endif
123 int do_get_thread_area(struct task_struct *p, int idx,
124 struct user_desc __user *u_info)
126 struct user_desc info;
128 if (idx == -1 && get_user(idx, &u_info->entry_number))
129 return -EFAULT;
131 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
132 return -EINVAL;
134 fill_user_desc(&info, idx,
135 &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]);
137 if (copy_to_user(u_info, &info, sizeof(info)))
138 return -EFAULT;
139 return 0;
142 asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
144 int ret = do_get_thread_area(current, -1, u_info);
145 asmlinkage_protect(1, ret, u_info);
146 return ret;
149 int regset_tls_active(struct task_struct *target,
150 const struct user_regset *regset)
152 struct thread_struct *t = &target->thread;
153 int n = GDT_ENTRY_TLS_ENTRIES;
154 while (n > 0 && desc_empty(&t->tls_array[n - 1]))
155 --n;
156 return n;
159 int regset_tls_get(struct task_struct *target, const struct user_regset *regset,
160 unsigned int pos, unsigned int count,
161 void *kbuf, void __user *ubuf)
163 const struct desc_struct *tls;
165 if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
166 (pos % sizeof(struct user_desc)) != 0 ||
167 (count % sizeof(struct user_desc)) != 0)
168 return -EINVAL;
170 pos /= sizeof(struct user_desc);
171 count /= sizeof(struct user_desc);
173 tls = &target->thread.tls_array[pos];
175 if (kbuf) {
176 struct user_desc *info = kbuf;
177 while (count-- > 0)
178 fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++,
179 tls++);
180 } else {
181 struct user_desc __user *u_info = ubuf;
182 while (count-- > 0) {
183 struct user_desc info;
184 fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++);
185 if (__copy_to_user(u_info++, &info, sizeof(info)))
186 return -EFAULT;
190 return 0;
193 int regset_tls_set(struct task_struct *target, const struct user_regset *regset,
194 unsigned int pos, unsigned int count,
195 const void *kbuf, const void __user *ubuf)
197 struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES];
198 const struct user_desc *info;
200 if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
201 (pos % sizeof(struct user_desc)) != 0 ||
202 (count % sizeof(struct user_desc)) != 0)
203 return -EINVAL;
205 if (kbuf)
206 info = kbuf;
207 else if (__copy_from_user(infobuf, ubuf, count))
208 return -EFAULT;
209 else
210 info = infobuf;
212 set_tls_desc(target,
213 GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)),
214 info, count / sizeof(struct user_desc));
216 return 0;