Commit | Line | Data |
---|---|---|
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> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/string.h> | |
12 | #include <linux/mm.h> | |
13 | #include <linux/smp.h> | |
1da177e4 LT |
14 | #include <linux/vmalloc.h> |
15 | #include <linux/slab.h> | |
16 | ||
17 | #include <asm/uaccess.h> | |
18 | #include <asm/system.h> | |
19 | #include <asm/ldt.h> | |
20 | #include <asm/desc.h> | |
21 | #include <asm/proto.h> | |
22 | ||
78aa1f66 | 23 | #ifdef CONFIG_SMP |
1da177e4 LT |
24 | static void flush_ldt(void *null) |
25 | { | |
26 | if (current->active_mm) | |
78aa1f66 | 27 | load_LDT(¤t->active_mm->context); |
1da177e4 LT |
28 | } |
29 | #endif | |
30 | ||
31 | static int alloc_ldt(mm_context_t *pc, unsigned mincount, int reload) | |
32 | { | |
33 | void *oldldt; | |
34 | void *newldt; | |
35 | unsigned oldsize; | |
36 | ||
37 | if (mincount <= (unsigned)pc->size) | |
38 | return 0; | |
39 | oldsize = pc->size; | |
78aa1f66 TG |
40 | mincount = (mincount + 511) & (~511); |
41 | if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE) | |
42 | newldt = vmalloc(mincount * LDT_ENTRY_SIZE); | |
1da177e4 | 43 | else |
78aa1f66 | 44 | newldt = kmalloc(mincount * LDT_ENTRY_SIZE, GFP_KERNEL); |
1da177e4 LT |
45 | |
46 | if (!newldt) | |
47 | return -ENOMEM; | |
48 | ||
49 | if (oldsize) | |
78aa1f66 | 50 | memcpy(newldt, pc->ldt, oldsize * LDT_ENTRY_SIZE); |
1da177e4 | 51 | oldldt = pc->ldt; |
78aa1f66 TG |
52 | memset(newldt + oldsize * LDT_ENTRY_SIZE, 0, |
53 | (mincount - oldsize) * LDT_ENTRY_SIZE); | |
1da177e4 LT |
54 | wmb(); |
55 | pc->ldt = newldt; | |
56 | wmb(); | |
57 | pc->size = mincount; | |
58 | wmb(); | |
59 | if (reload) { | |
60 | #ifdef CONFIG_SMP | |
61 | cpumask_t mask; | |
62 | ||
63 | preempt_disable(); | |
64 | mask = cpumask_of_cpu(smp_processor_id()); | |
65 | load_LDT(pc); | |
66 | if (!cpus_equal(current->mm->cpu_vm_mask, mask)) | |
67 | smp_call_function(flush_ldt, NULL, 1, 1); | |
68 | preempt_enable(); | |
69 | #else | |
70 | load_LDT(pc); | |
71 | #endif | |
72 | } | |
73 | if (oldsize) { | |
78aa1f66 | 74 | if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE) |
1da177e4 LT |
75 | vfree(oldldt); |
76 | else | |
77 | kfree(oldldt); | |
78 | } | |
79 | return 0; | |
80 | } | |
81 | ||
82 | static inline int copy_ldt(mm_context_t *new, mm_context_t *old) | |
83 | { | |
84 | int err = alloc_ldt(new, old->size, 0); | |
78aa1f66 | 85 | |
1da177e4 LT |
86 | if (err < 0) |
87 | return err; | |
78aa1f66 | 88 | memcpy(new->ldt, old->ldt, old->size * LDT_ENTRY_SIZE); |
1da177e4 LT |
89 | return 0; |
90 | } | |
91 | ||
92 | /* | |
93 | * we do not have to muck with descriptors here, that is | |
94 | * done in switch_mm() as needed. | |
95 | */ | |
96 | int init_new_context(struct task_struct *tsk, struct mm_struct *mm) | |
97 | { | |
78aa1f66 | 98 | struct mm_struct *old_mm; |
1da177e4 LT |
99 | int retval = 0; |
100 | ||
c7537ab2 | 101 | mutex_init(&mm->context.lock); |
1da177e4 LT |
102 | mm->context.size = 0; |
103 | old_mm = current->mm; | |
104 | if (old_mm && old_mm->context.size > 0) { | |
c7537ab2 | 105 | mutex_lock(&old_mm->context.lock); |
1da177e4 | 106 | retval = copy_ldt(&mm->context, &old_mm->context); |
c7537ab2 | 107 | mutex_unlock(&old_mm->context.lock); |
1da177e4 LT |
108 | } |
109 | return retval; | |
110 | } | |
111 | ||
112 | /* | |
1da177e4 LT |
113 | * Don't touch the LDT register - we're already in the next thread. |
114 | */ | |
115 | void destroy_context(struct mm_struct *mm) | |
116 | { | |
117 | if (mm->context.size) { | |
78aa1f66 | 118 | if ((unsigned)mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE) |
1da177e4 LT |
119 | vfree(mm->context.ldt); |
120 | else | |
121 | kfree(mm->context.ldt); | |
122 | mm->context.size = 0; | |
123 | } | |
124 | } | |
125 | ||
78aa1f66 | 126 | static int read_ldt(void __user *ptr, unsigned long bytecount) |
1da177e4 LT |
127 | { |
128 | int err; | |
129 | unsigned long size; | |
78aa1f66 | 130 | struct mm_struct *mm = current->mm; |
1da177e4 LT |
131 | |
132 | if (!mm->context.size) | |
133 | return 0; | |
78aa1f66 TG |
134 | if (bytecount > LDT_ENTRY_SIZE * LDT_ENTRIES) |
135 | bytecount = LDT_ENTRY_SIZE * LDT_ENTRIES; | |
1da177e4 | 136 | |
c7537ab2 | 137 | mutex_lock(&mm->context.lock); |
78aa1f66 | 138 | size = mm->context.size * LDT_ENTRY_SIZE; |
1da177e4 LT |
139 | if (size > bytecount) |
140 | size = bytecount; | |
141 | ||
142 | err = 0; | |
143 | if (copy_to_user(ptr, mm->context.ldt, size)) | |
144 | err = -EFAULT; | |
c7537ab2 | 145 | mutex_unlock(&mm->context.lock); |
1da177e4 LT |
146 | if (err < 0) |
147 | goto error_return; | |
148 | if (size != bytecount) { | |
149 | /* zero-fill the rest */ | |
78aa1f66 | 150 | if (clear_user(ptr + size, bytecount - size) != 0) { |
1da177e4 LT |
151 | err = -EFAULT; |
152 | goto error_return; | |
153 | } | |
154 | } | |
155 | return bytecount; | |
156 | error_return: | |
157 | return err; | |
158 | } | |
159 | ||
78aa1f66 | 160 | static int read_default_ldt(void __user *ptr, unsigned long bytecount) |
1da177e4 | 161 | { |
78aa1f66 | 162 | /* Arbitrary number */ |
1da177e4 | 163 | /* x86-64 default LDT is all zeros */ |
78aa1f66 TG |
164 | if (bytecount > 128) |
165 | bytecount = 128; | |
1da177e4 LT |
166 | if (clear_user(ptr, bytecount)) |
167 | return -EFAULT; | |
78aa1f66 | 168 | return bytecount; |
1da177e4 LT |
169 | } |
170 | ||
78aa1f66 | 171 | static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode) |
1da177e4 LT |
172 | { |
173 | struct task_struct *me = current; | |
78aa1f66 | 174 | struct mm_struct *mm = me->mm; |
fc2d625c | 175 | __u32 entry_1, entry_2; |
1da177e4 LT |
176 | int error; |
177 | struct user_desc ldt_info; | |
178 | ||
179 | error = -EINVAL; | |
180 | ||
181 | if (bytecount != sizeof(ldt_info)) | |
182 | goto out; | |
78aa1f66 | 183 | error = -EFAULT; |
1da177e4 LT |
184 | if (copy_from_user(&ldt_info, ptr, bytecount)) |
185 | goto out; | |
186 | ||
187 | error = -EINVAL; | |
188 | if (ldt_info.entry_number >= LDT_ENTRIES) | |
189 | goto out; | |
190 | if (ldt_info.contents == 3) { | |
191 | if (oldmode) | |
192 | goto out; | |
193 | if (ldt_info.seg_not_present == 0) | |
194 | goto out; | |
195 | } | |
196 | ||
c7537ab2 | 197 | mutex_lock(&mm->context.lock); |
1da177e4 | 198 | if (ldt_info.entry_number >= (unsigned)mm->context.size) { |
78aa1f66 TG |
199 | error = alloc_ldt(¤t->mm->context, |
200 | ldt_info.entry_number + 1, 1); | |
1da177e4 LT |
201 | if (error < 0) |
202 | goto out_unlock; | |
203 | } | |
204 | ||
78aa1f66 TG |
205 | /* Allow LDTs to be cleared by the user. */ |
206 | if (ldt_info.base_addr == 0 && ldt_info.limit == 0) { | |
1da177e4 LT |
207 | if (oldmode || LDT_empty(&ldt_info)) { |
208 | entry_1 = 0; | |
209 | entry_2 = 0; | |
210 | goto install; | |
211 | } | |
212 | } | |
213 | ||
214 | entry_1 = LDT_entry_a(&ldt_info); | |
215 | entry_2 = LDT_entry_b(&ldt_info); | |
216 | if (oldmode) | |
217 | entry_2 &= ~(1 << 20); | |
218 | ||
219 | /* Install the new entry ... */ | |
220 | install: | |
fc2d625c TG |
221 | write_ldt_entry(mm->context.ldt, ldt_info.entry_number, entry_1, |
222 | entry_2); | |
1da177e4 LT |
223 | error = 0; |
224 | ||
225 | out_unlock: | |
c7537ab2 | 226 | mutex_unlock(&mm->context.lock); |
1da177e4 LT |
227 | out: |
228 | return error; | |
229 | } | |
230 | ||
78aa1f66 TG |
231 | asmlinkage int sys_modify_ldt(int func, void __user *ptr, |
232 | unsigned long bytecount) | |
1da177e4 LT |
233 | { |
234 | int ret = -ENOSYS; | |
235 | ||
236 | switch (func) { | |
237 | case 0: | |
238 | ret = read_ldt(ptr, bytecount); | |
239 | break; | |
240 | case 1: | |
241 | ret = write_ldt(ptr, bytecount, 1); | |
242 | break; | |
243 | case 2: | |
244 | ret = read_default_ldt(ptr, bytecount); | |
245 | break; | |
246 | case 0x11: | |
247 | ret = write_ldt(ptr, bytecount, 0); | |
248 | break; | |
249 | } | |
250 | return ret; | |
251 | } |