Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
f30c2269 | 2 | * linux/arch/i386/kernel/ldt.c |
1da177e4 LT |
3 | * |
4 | * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds | |
5 | * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> | |
6 | */ | |
7 | ||
8 | #include <linux/errno.h> | |
9 | #include <linux/sched.h> | |
10 | #include <linux/string.h> | |
11 | #include <linux/mm.h> | |
12 | #include <linux/smp.h> | |
1da177e4 LT |
13 | #include <linux/vmalloc.h> |
14 | #include <linux/slab.h> | |
15 | ||
16 | #include <asm/uaccess.h> | |
17 | #include <asm/system.h> | |
18 | #include <asm/ldt.h> | |
19 | #include <asm/desc.h> | |
8d1ed636 | 20 | #include <asm/mmu_context.h> |
1da177e4 LT |
21 | |
22 | #ifdef CONFIG_SMP /* avoids "defined but not used" warnig */ | |
23 | static void flush_ldt(void *null) | |
24 | { | |
25 | if (current->active_mm) | |
26 | load_LDT(¤t->active_mm->context); | |
27 | } | |
28 | #endif | |
29 | ||
30 | static int alloc_ldt(mm_context_t *pc, int mincount, int reload) | |
31 | { | |
32 | void *oldldt; | |
33 | void *newldt; | |
34 | int oldsize; | |
35 | ||
36 | if (mincount <= pc->size) | |
37 | return 0; | |
38 | oldsize = pc->size; | |
39 | mincount = (mincount+511)&(~511); | |
40 | if (mincount*LDT_ENTRY_SIZE > PAGE_SIZE) | |
41 | newldt = vmalloc(mincount*LDT_ENTRY_SIZE); | |
42 | else | |
43 | newldt = kmalloc(mincount*LDT_ENTRY_SIZE, GFP_KERNEL); | |
44 | ||
45 | if (!newldt) | |
46 | return -ENOMEM; | |
47 | ||
48 | if (oldsize) | |
49 | memcpy(newldt, pc->ldt, oldsize*LDT_ENTRY_SIZE); | |
50 | oldldt = pc->ldt; | |
51 | memset(newldt+oldsize*LDT_ENTRY_SIZE, 0, (mincount-oldsize)*LDT_ENTRY_SIZE); | |
52 | pc->ldt = newldt; | |
53 | wmb(); | |
54 | pc->size = mincount; | |
55 | wmb(); | |
56 | ||
57 | if (reload) { | |
58 | #ifdef CONFIG_SMP | |
59 | cpumask_t mask; | |
60 | preempt_disable(); | |
61 | load_LDT(pc); | |
62 | mask = cpumask_of_cpu(smp_processor_id()); | |
63 | if (!cpus_equal(current->mm->cpu_vm_mask, mask)) | |
64 | smp_call_function(flush_ldt, NULL, 1, 1); | |
65 | preempt_enable(); | |
66 | #else | |
67 | load_LDT(pc); | |
68 | #endif | |
69 | } | |
70 | if (oldsize) { | |
71 | if (oldsize*LDT_ENTRY_SIZE > PAGE_SIZE) | |
72 | vfree(oldldt); | |
73 | else | |
74 | kfree(oldldt); | |
75 | } | |
76 | return 0; | |
77 | } | |
78 | ||
79 | static inline int copy_ldt(mm_context_t *new, mm_context_t *old) | |
80 | { | |
81 | int err = alloc_ldt(new, old->size, 0); | |
82 | if (err < 0) | |
83 | return err; | |
84 | memcpy(new->ldt, old->ldt, old->size*LDT_ENTRY_SIZE); | |
85 | return 0; | |
86 | } | |
87 | ||
88 | /* | |
89 | * we do not have to muck with descriptors here, that is | |
90 | * done in switch_mm() as needed. | |
91 | */ | |
92 | int init_new_context(struct task_struct *tsk, struct mm_struct *mm) | |
93 | { | |
94 | struct mm_struct * old_mm; | |
95 | int retval = 0; | |
96 | ||
97 | init_MUTEX(&mm->context.sem); | |
98 | mm->context.size = 0; | |
99 | old_mm = current->mm; | |
100 | if (old_mm && old_mm->context.size > 0) { | |
101 | down(&old_mm->context.sem); | |
102 | retval = copy_ldt(&mm->context, &old_mm->context); | |
103 | up(&old_mm->context.sem); | |
104 | } | |
105 | return retval; | |
106 | } | |
107 | ||
108 | /* | |
109 | * No need to lock the MM as we are the last user | |
110 | */ | |
111 | void destroy_context(struct mm_struct *mm) | |
112 | { | |
113 | if (mm->context.size) { | |
114 | if (mm == current->active_mm) | |
115 | clear_LDT(); | |
116 | if (mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE) | |
117 | vfree(mm->context.ldt); | |
118 | else | |
119 | kfree(mm->context.ldt); | |
120 | mm->context.size = 0; | |
121 | } | |
122 | } | |
123 | ||
124 | static int read_ldt(void __user * ptr, unsigned long bytecount) | |
125 | { | |
126 | int err; | |
127 | unsigned long size; | |
128 | struct mm_struct * mm = current->mm; | |
129 | ||
130 | if (!mm->context.size) | |
131 | return 0; | |
132 | if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES) | |
133 | bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES; | |
134 | ||
135 | down(&mm->context.sem); | |
136 | size = mm->context.size*LDT_ENTRY_SIZE; | |
137 | if (size > bytecount) | |
138 | size = bytecount; | |
139 | ||
140 | err = 0; | |
141 | if (copy_to_user(ptr, mm->context.ldt, size)) | |
142 | err = -EFAULT; | |
143 | up(&mm->context.sem); | |
144 | if (err < 0) | |
145 | goto error_return; | |
146 | if (size != bytecount) { | |
147 | /* zero-fill the rest */ | |
148 | if (clear_user(ptr+size, bytecount-size) != 0) { | |
149 | err = -EFAULT; | |
150 | goto error_return; | |
151 | } | |
152 | } | |
153 | return bytecount; | |
154 | error_return: | |
155 | return err; | |
156 | } | |
157 | ||
158 | static int read_default_ldt(void __user * ptr, unsigned long bytecount) | |
159 | { | |
160 | int err; | |
161 | unsigned long size; | |
1da177e4 LT |
162 | |
163 | err = 0; | |
1da177e4 LT |
164 | size = 5*sizeof(struct desc_struct); |
165 | if (size > bytecount) | |
166 | size = bytecount; | |
167 | ||
168 | err = size; | |
e5e3a042 | 169 | if (clear_user(ptr, size)) |
1da177e4 LT |
170 | err = -EFAULT; |
171 | ||
172 | return err; | |
173 | } | |
174 | ||
175 | static int write_ldt(void __user * ptr, unsigned long bytecount, int oldmode) | |
176 | { | |
177 | struct mm_struct * mm = current->mm; | |
f2f30ebc | 178 | __u32 entry_1, entry_2; |
1da177e4 LT |
179 | int error; |
180 | struct user_desc ldt_info; | |
181 | ||
182 | error = -EINVAL; | |
183 | if (bytecount != sizeof(ldt_info)) | |
184 | goto out; | |
185 | error = -EFAULT; | |
186 | if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info))) | |
187 | goto out; | |
188 | ||
189 | error = -EINVAL; | |
190 | if (ldt_info.entry_number >= LDT_ENTRIES) | |
191 | goto out; | |
192 | if (ldt_info.contents == 3) { | |
193 | if (oldmode) | |
194 | goto out; | |
195 | if (ldt_info.seg_not_present == 0) | |
196 | goto out; | |
197 | } | |
198 | ||
199 | down(&mm->context.sem); | |
200 | if (ldt_info.entry_number >= mm->context.size) { | |
201 | error = alloc_ldt(¤t->mm->context, ldt_info.entry_number+1, 1); | |
202 | if (error < 0) | |
203 | goto out_unlock; | |
204 | } | |
205 | ||
1da177e4 LT |
206 | /* Allow LDTs to be cleared by the user. */ |
207 | if (ldt_info.base_addr == 0 && ldt_info.limit == 0) { | |
208 | if (oldmode || LDT_empty(&ldt_info)) { | |
209 | entry_1 = 0; | |
210 | entry_2 = 0; | |
211 | goto install; | |
212 | } | |
213 | } | |
214 | ||
215 | entry_1 = LDT_entry_a(&ldt_info); | |
216 | entry_2 = LDT_entry_b(&ldt_info); | |
217 | if (oldmode) | |
218 | entry_2 &= ~(1 << 20); | |
219 | ||
220 | /* Install the new entry ... */ | |
221 | install: | |
f2f30ebc | 222 | write_ldt_entry(mm->context.ldt, ldt_info.entry_number, entry_1, entry_2); |
1da177e4 LT |
223 | error = 0; |
224 | ||
225 | out_unlock: | |
226 | up(&mm->context.sem); | |
227 | out: | |
228 | return error; | |
229 | } | |
230 | ||
231 | asmlinkage int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount) | |
232 | { | |
233 | int ret = -ENOSYS; | |
234 | ||
235 | switch (func) { | |
236 | case 0: | |
237 | ret = read_ldt(ptr, bytecount); | |
238 | break; | |
239 | case 1: | |
240 | ret = write_ldt(ptr, bytecount, 1); | |
241 | break; | |
242 | case 2: | |
243 | ret = read_default_ldt(ptr, bytecount); | |
244 | break; | |
245 | case 0x11: | |
246 | ret = write_ldt(ptr, bytecount, 0); | |
247 | break; | |
248 | } | |
249 | return ret; | |
250 | } |