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Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds |
3 | * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> | |
4 | * Copyright (C) 2002 Andi Kleen | |
78aa1f66 | 5 | * |
1da177e4 LT |
6 | * This handles calls from both 32bit and 64bit mode. |
7 | */ | |
8 | ||
9 | #include <linux/errno.h> | |
5a0e3ad6 | 10 | #include <linux/gfp.h> |
1da177e4 LT |
11 | #include <linux/sched.h> |
12 | #include <linux/string.h> | |
13 | #include <linux/mm.h> | |
14 | #include <linux/smp.h> | |
1da177e4 | 15 | #include <linux/vmalloc.h> |
423a5405 | 16 | #include <linux/uaccess.h> |
1da177e4 | 17 | |
1da177e4 LT |
18 | #include <asm/system.h> |
19 | #include <asm/ldt.h> | |
20 | #include <asm/desc.h> | |
70f5088d | 21 | #include <asm/mmu_context.h> |
bbc1f698 | 22 | #include <asm/syscalls.h> |
1da177e4 | 23 | |
78aa1f66 | 24 | #ifdef CONFIG_SMP |
b478458a | 25 | static void flush_ldt(void *current_mm) |
1da177e4 | 26 | { |
b478458a | 27 | if (current->active_mm == current_mm) |
78aa1f66 | 28 | load_LDT(¤t->active_mm->context); |
1da177e4 LT |
29 | } |
30 | #endif | |
31 | ||
70f5088d | 32 | static int alloc_ldt(mm_context_t *pc, int mincount, int reload) |
1da177e4 | 33 | { |
70f5088d TG |
34 | void *oldldt, *newldt; |
35 | int oldsize; | |
1da177e4 | 36 | |
70f5088d | 37 | if (mincount <= pc->size) |
1da177e4 LT |
38 | return 0; |
39 | oldsize = pc->size; | |
fa0c864d CG |
40 | mincount = (mincount + (PAGE_SIZE / LDT_ENTRY_SIZE - 1)) & |
41 | (~(PAGE_SIZE / LDT_ENTRY_SIZE - 1)); | |
78aa1f66 TG |
42 | if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE) |
43 | newldt = vmalloc(mincount * LDT_ENTRY_SIZE); | |
1da177e4 | 44 | else |
4dbf7af6 | 45 | newldt = (void *)__get_free_page(GFP_KERNEL); |
1da177e4 LT |
46 | |
47 | if (!newldt) | |
48 | return -ENOMEM; | |
49 | ||
50 | if (oldsize) | |
78aa1f66 | 51 | memcpy(newldt, pc->ldt, oldsize * LDT_ENTRY_SIZE); |
1da177e4 | 52 | oldldt = pc->ldt; |
78aa1f66 TG |
53 | memset(newldt + oldsize * LDT_ENTRY_SIZE, 0, |
54 | (mincount - oldsize) * LDT_ENTRY_SIZE); | |
77e463d1 | 55 | |
38ffbe66 JF |
56 | paravirt_alloc_ldt(newldt, mincount); |
57 | ||
77e463d1 TG |
58 | #ifdef CONFIG_X86_64 |
59 | /* CHECKME: Do we really need this ? */ | |
1da177e4 | 60 | wmb(); |
77e463d1 | 61 | #endif |
1da177e4 LT |
62 | pc->ldt = newldt; |
63 | wmb(); | |
64 | pc->size = mincount; | |
65 | wmb(); | |
70f5088d | 66 | |
1da177e4 LT |
67 | if (reload) { |
68 | #ifdef CONFIG_SMP | |
1da177e4 | 69 | preempt_disable(); |
1da177e4 | 70 | load_LDT(pc); |
78f1c4d6 RR |
71 | if (!cpumask_equal(mm_cpumask(current->mm), |
72 | cpumask_of(smp_processor_id()))) | |
1a781a77 | 73 | smp_call_function(flush_ldt, current->mm, 1); |
1da177e4 LT |
74 | preempt_enable(); |
75 | #else | |
76 | load_LDT(pc); | |
77 | #endif | |
78 | } | |
79 | if (oldsize) { | |
38ffbe66 | 80 | paravirt_free_ldt(oldldt, oldsize); |
78aa1f66 | 81 | if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE) |
1da177e4 LT |
82 | vfree(oldldt); |
83 | else | |
4dbf7af6 | 84 | put_page(virt_to_page(oldldt)); |
1da177e4 LT |
85 | } |
86 | return 0; | |
87 | } | |
88 | ||
89 | static inline int copy_ldt(mm_context_t *new, mm_context_t *old) | |
90 | { | |
91 | int err = alloc_ldt(new, old->size, 0); | |
38ffbe66 | 92 | int i; |
78aa1f66 | 93 | |
1da177e4 LT |
94 | if (err < 0) |
95 | return err; | |
38ffbe66 | 96 | |
423a5405 | 97 | for (i = 0; i < old->size; i++) |
38ffbe66 | 98 | write_ldt_entry(new->ldt, i, old->ldt + i * LDT_ENTRY_SIZE); |
1da177e4 LT |
99 | return 0; |
100 | } | |
101 | ||
102 | /* | |
103 | * we do not have to muck with descriptors here, that is | |
104 | * done in switch_mm() as needed. | |
105 | */ | |
106 | int init_new_context(struct task_struct *tsk, struct mm_struct *mm) | |
107 | { | |
78aa1f66 | 108 | struct mm_struct *old_mm; |
1da177e4 LT |
109 | int retval = 0; |
110 | ||
c7537ab2 | 111 | mutex_init(&mm->context.lock); |
1da177e4 LT |
112 | mm->context.size = 0; |
113 | old_mm = current->mm; | |
114 | if (old_mm && old_mm->context.size > 0) { | |
c7537ab2 | 115 | mutex_lock(&old_mm->context.lock); |
1da177e4 | 116 | retval = copy_ldt(&mm->context, &old_mm->context); |
c7537ab2 | 117 | mutex_unlock(&old_mm->context.lock); |
1da177e4 LT |
118 | } |
119 | return retval; | |
120 | } | |
121 | ||
122 | /* | |
77e463d1 TG |
123 | * No need to lock the MM as we are the last user |
124 | * | |
125 | * 64bit: Don't touch the LDT register - we're already in the next thread. | |
1da177e4 LT |
126 | */ |
127 | void destroy_context(struct mm_struct *mm) | |
128 | { | |
129 | if (mm->context.size) { | |
77e463d1 TG |
130 | #ifdef CONFIG_X86_32 |
131 | /* CHECKME: Can this ever happen ? */ | |
132 | if (mm == current->active_mm) | |
133 | clear_LDT(); | |
134 | #endif | |
38ffbe66 | 135 | paravirt_free_ldt(mm->context.ldt, mm->context.size); |
70f5088d | 136 | if (mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE) |
1da177e4 LT |
137 | vfree(mm->context.ldt); |
138 | else | |
4dbf7af6 | 139 | put_page(virt_to_page(mm->context.ldt)); |
1da177e4 LT |
140 | mm->context.size = 0; |
141 | } | |
142 | } | |
143 | ||
78aa1f66 | 144 | static int read_ldt(void __user *ptr, unsigned long bytecount) |
1da177e4 LT |
145 | { |
146 | int err; | |
147 | unsigned long size; | |
78aa1f66 | 148 | struct mm_struct *mm = current->mm; |
1da177e4 LT |
149 | |
150 | if (!mm->context.size) | |
151 | return 0; | |
78aa1f66 TG |
152 | if (bytecount > LDT_ENTRY_SIZE * LDT_ENTRIES) |
153 | bytecount = LDT_ENTRY_SIZE * LDT_ENTRIES; | |
1da177e4 | 154 | |
c7537ab2 | 155 | mutex_lock(&mm->context.lock); |
78aa1f66 | 156 | size = mm->context.size * LDT_ENTRY_SIZE; |
1da177e4 LT |
157 | if (size > bytecount) |
158 | size = bytecount; | |
159 | ||
160 | err = 0; | |
161 | if (copy_to_user(ptr, mm->context.ldt, size)) | |
162 | err = -EFAULT; | |
c7537ab2 | 163 | mutex_unlock(&mm->context.lock); |
1da177e4 LT |
164 | if (err < 0) |
165 | goto error_return; | |
166 | if (size != bytecount) { | |
167 | /* zero-fill the rest */ | |
78aa1f66 | 168 | if (clear_user(ptr + size, bytecount - size) != 0) { |
1da177e4 LT |
169 | err = -EFAULT; |
170 | goto error_return; | |
171 | } | |
172 | } | |
173 | return bytecount; | |
174 | error_return: | |
175 | return err; | |
176 | } | |
177 | ||
78aa1f66 | 178 | static int read_default_ldt(void __user *ptr, unsigned long bytecount) |
1da177e4 | 179 | { |
77e463d1 TG |
180 | /* CHECKME: Can we use _one_ random number ? */ |
181 | #ifdef CONFIG_X86_32 | |
182 | unsigned long size = 5 * sizeof(struct desc_struct); | |
183 | #else | |
184 | unsigned long size = 128; | |
185 | #endif | |
186 | if (bytecount > size) | |
187 | bytecount = size; | |
1da177e4 LT |
188 | if (clear_user(ptr, bytecount)) |
189 | return -EFAULT; | |
78aa1f66 | 190 | return bytecount; |
1da177e4 LT |
191 | } |
192 | ||
78aa1f66 | 193 | static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode) |
1da177e4 | 194 | { |
70f5088d | 195 | struct mm_struct *mm = current->mm; |
5af72502 | 196 | struct desc_struct ldt; |
1da177e4 LT |
197 | int error; |
198 | struct user_desc ldt_info; | |
199 | ||
200 | error = -EINVAL; | |
1da177e4 LT |
201 | if (bytecount != sizeof(ldt_info)) |
202 | goto out; | |
78aa1f66 | 203 | error = -EFAULT; |
70f5088d | 204 | if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info))) |
1da177e4 LT |
205 | goto out; |
206 | ||
207 | error = -EINVAL; | |
208 | if (ldt_info.entry_number >= LDT_ENTRIES) | |
209 | goto out; | |
210 | if (ldt_info.contents == 3) { | |
211 | if (oldmode) | |
212 | goto out; | |
213 | if (ldt_info.seg_not_present == 0) | |
214 | goto out; | |
215 | } | |
216 | ||
c7537ab2 | 217 | mutex_lock(&mm->context.lock); |
70f5088d | 218 | if (ldt_info.entry_number >= mm->context.size) { |
78aa1f66 TG |
219 | error = alloc_ldt(¤t->mm->context, |
220 | ldt_info.entry_number + 1, 1); | |
1da177e4 LT |
221 | if (error < 0) |
222 | goto out_unlock; | |
223 | } | |
224 | ||
78aa1f66 TG |
225 | /* Allow LDTs to be cleared by the user. */ |
226 | if (ldt_info.base_addr == 0 && ldt_info.limit == 0) { | |
1da177e4 | 227 | if (oldmode || LDT_empty(&ldt_info)) { |
5af72502 | 228 | memset(&ldt, 0, sizeof(ldt)); |
1da177e4 LT |
229 | goto install; |
230 | } | |
231 | } | |
232 | ||
80fbb69a | 233 | fill_ldt(&ldt, &ldt_info); |
1da177e4 | 234 | if (oldmode) |
5af72502 | 235 | ldt.avl = 0; |
1da177e4 LT |
236 | |
237 | /* Install the new entry ... */ | |
238 | install: | |
75b8bb3e | 239 | write_ldt_entry(mm->context.ldt, ldt_info.entry_number, &ldt); |
1da177e4 LT |
240 | error = 0; |
241 | ||
242 | out_unlock: | |
c7537ab2 | 243 | mutex_unlock(&mm->context.lock); |
1da177e4 LT |
244 | out: |
245 | return error; | |
246 | } | |
247 | ||
78aa1f66 TG |
248 | asmlinkage int sys_modify_ldt(int func, void __user *ptr, |
249 | unsigned long bytecount) | |
1da177e4 LT |
250 | { |
251 | int ret = -ENOSYS; | |
252 | ||
253 | switch (func) { | |
254 | case 0: | |
255 | ret = read_ldt(ptr, bytecount); | |
256 | break; | |
257 | case 1: | |
258 | ret = write_ldt(ptr, bytecount, 1); | |
259 | break; | |
260 | case 2: | |
261 | ret = read_default_ldt(ptr, bytecount); | |
262 | break; | |
263 | case 0x11: | |
264 | ret = write_ldt(ptr, bytecount, 0); | |
265 | break; | |
266 | } | |
267 | return ret; | |
268 | } |