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1/*
2 * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
3 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
4 * Copyright (C) 2002 Andi Kleen
5 *
6 * This handles calls from both 32bit and 64bit mode.
7 */
8
9#include <linux/errno.h>
10#include <linux/gfp.h>
11#include <linux/sched.h>
12#include <linux/string.h>
13#include <linux/mm.h>
14#include <linux/smp.h>
15#include <linux/vmalloc.h>
16#include <linux/uaccess.h>
17
18#include <asm/ldt.h>
19#include <asm/desc.h>
20#include <asm/mmu_context.h>
21#include <asm/syscalls.h>
22
23int sysctl_ldt16 = 0;
24
25#ifdef CONFIG_SMP
26static void flush_ldt(void *current_mm)
27{
28 if (current->active_mm == current_mm)
29 load_LDT(¤t->active_mm->context);
30}
31#endif
32
33static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
34{
35 void *oldldt, *newldt;
36 int oldsize;
37
38 if (mincount <= pc->size)
39 return 0;
40 oldsize = pc->size;
41 mincount = (mincount + (PAGE_SIZE / LDT_ENTRY_SIZE - 1)) &
42 (~(PAGE_SIZE / LDT_ENTRY_SIZE - 1));
43 if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE)
44 newldt = vmalloc(mincount * LDT_ENTRY_SIZE);
45 else
46 newldt = (void *)__get_free_page(GFP_KERNEL);
47
48 if (!newldt)
49 return -ENOMEM;
50
51 if (oldsize)
52 memcpy(newldt, pc->ldt, oldsize * LDT_ENTRY_SIZE);
53 oldldt = pc->ldt;
54 memset(newldt + oldsize * LDT_ENTRY_SIZE, 0,
55 (mincount - oldsize) * LDT_ENTRY_SIZE);
56
57 paravirt_alloc_ldt(newldt, mincount);
58
59#ifdef CONFIG_X86_64
60 /* CHECKME: Do we really need this ? */
61 wmb();
62#endif
63 pc->ldt = newldt;
64 wmb();
65 pc->size = mincount;
66 wmb();
67
68 if (reload) {
69#ifdef CONFIG_SMP
70 preempt_disable();
71 load_LDT(pc);
72 if (!cpumask_equal(mm_cpumask(current->mm),
73 cpumask_of(smp_processor_id())))
74 smp_call_function(flush_ldt, current->mm, 1);
75 preempt_enable();
76#else
77 load_LDT(pc);
78#endif
79 }
80 if (oldsize) {
81 paravirt_free_ldt(oldldt, oldsize);
82 if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
83 vfree(oldldt);
84 else
85 put_page(virt_to_page(oldldt));
86 }
87 return 0;
88}
89
90static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
91{
92 int err = alloc_ldt(new, old->size, 0);
93 int i;
94
95 if (err < 0)
96 return err;
97
98 for (i = 0; i < old->size; i++)
99 write_ldt_entry(new->ldt, i, old->ldt + i * LDT_ENTRY_SIZE);
100 return 0;
101}
102
103/*
104 * we do not have to muck with descriptors here, that is
105 * done in switch_mm() as needed.
106 */
107int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
108{
109 struct mm_struct *old_mm;
110 int retval = 0;
111
112 mutex_init(&mm->context.lock);
113 mm->context.size = 0;
114 old_mm = current->mm;
115 if (old_mm && old_mm->context.size > 0) {
116 mutex_lock(&old_mm->context.lock);
117 retval = copy_ldt(&mm->context, &old_mm->context);
118 mutex_unlock(&old_mm->context.lock);
119 }
120 return retval;
121}
122
123/*
124 * No need to lock the MM as we are the last user
125 *
126 * 64bit: Don't touch the LDT register - we're already in the next thread.
127 */
128void destroy_context(struct mm_struct *mm)
129{
130 if (mm->context.size) {
131#ifdef CONFIG_X86_32
132 /* CHECKME: Can this ever happen ? */
133 if (mm == current->active_mm)
134 clear_LDT();
135#endif
136 paravirt_free_ldt(mm->context.ldt, mm->context.size);
137 if (mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE)
138 vfree(mm->context.ldt);
139 else
140 put_page(virt_to_page(mm->context.ldt));
141 mm->context.size = 0;
142 }
143}
144
145static int read_ldt(void __user *ptr, unsigned long bytecount)
146{
147 int err;
148 unsigned long size;
149 struct mm_struct *mm = current->mm;
150
151 if (!mm->context.size)
152 return 0;
153 if (bytecount > LDT_ENTRY_SIZE * LDT_ENTRIES)
154 bytecount = LDT_ENTRY_SIZE * LDT_ENTRIES;
155
156 mutex_lock(&mm->context.lock);
157 size = mm->context.size * LDT_ENTRY_SIZE;
158 if (size > bytecount)
159 size = bytecount;
160
161 err = 0;
162 if (copy_to_user(ptr, mm->context.ldt, size))
163 err = -EFAULT;
164 mutex_unlock(&mm->context.lock);
165 if (err < 0)
166 goto error_return;
167 if (size != bytecount) {
168 /* zero-fill the rest */
169 if (clear_user(ptr + size, bytecount - size) != 0) {
170 err = -EFAULT;
171 goto error_return;
172 }
173 }
174 return bytecount;
175error_return:
176 return err;
177}
178
179static int read_default_ldt(void __user *ptr, unsigned long bytecount)
180{
181 /* CHECKME: Can we use _one_ random number ? */
182#ifdef CONFIG_X86_32
183 unsigned long size = 5 * sizeof(struct desc_struct);
184#else
185 unsigned long size = 128;
186#endif
187 if (bytecount > size)
188 bytecount = size;
189 if (clear_user(ptr, bytecount))
190 return -EFAULT;
191 return bytecount;
192}
193
194static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
195{
196 struct mm_struct *mm = current->mm;
197 struct desc_struct ldt;
198 int error;
199 struct user_desc ldt_info;
200
201 error = -EINVAL;
202 if (bytecount != sizeof(ldt_info))
203 goto out;
204 error = -EFAULT;
205 if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
206 goto out;
207
208 error = -EINVAL;
209 if (ldt_info.entry_number >= LDT_ENTRIES)
210 goto out;
211 if (ldt_info.contents == 3) {
212 if (oldmode)
213 goto out;
214 if (ldt_info.seg_not_present == 0)
215 goto out;
216 }
217
218 mutex_lock(&mm->context.lock);
219 if (ldt_info.entry_number >= mm->context.size) {
220 error = alloc_ldt(¤t->mm->context,
221 ldt_info.entry_number + 1, 1);
222 if (error < 0)
223 goto out_unlock;
224 }
225
226 /* Allow LDTs to be cleared by the user. */
227 if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
228 if (oldmode || LDT_empty(&ldt_info)) {
229 memset(&ldt, 0, sizeof(ldt));
230 goto install;
231 }
232 }
233
234 /*
235 * On x86-64 we do not support 16-bit segments due to
236 * IRET leaking the high bits of the kernel stack address.
237 */
238#ifdef CONFIG_X86_64
239 if (!ldt_info.seg_32bit && !sysctl_ldt16) {
240 error = -EINVAL;
241 goto out_unlock;
242 }
243#endif
244
245 fill_ldt(&ldt, &ldt_info);
246 if (oldmode)
247 ldt.avl = 0;
248
249 /* Install the new entry ... */
250install:
251 write_ldt_entry(mm->context.ldt, ldt_info.entry_number, &ldt);
252 error = 0;
253
254out_unlock:
255 mutex_unlock(&mm->context.lock);
256out:
257 return error;
258}
259
260asmlinkage int sys_modify_ldt(int func, void __user *ptr,
261 unsigned long bytecount)
262{
263 int ret = -ENOSYS;
264
265 switch (func) {
266 case 0:
267 ret = read_ldt(ptr, bytecount);
268 break;
269 case 1:
270 ret = write_ldt(ptr, bytecount, 1);
271 break;
272 case 2:
273 ret = read_default_ldt(ptr, bytecount);
274 break;
275 case 0x11:
276 ret = write_ldt(ptr, bytecount, 0);
277 break;
278 }
279 return ret;
280}
1/*
2 * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
3 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
4 * Copyright (C) 2002 Andi Kleen
5 *
6 * This handles calls from both 32bit and 64bit mode.
7 */
8
9#include <linux/errno.h>
10#include <linux/gfp.h>
11#include <linux/sched.h>
12#include <linux/string.h>
13#include <linux/mm.h>
14#include <linux/smp.h>
15#include <linux/vmalloc.h>
16#include <linux/uaccess.h>
17
18#include <asm/ldt.h>
19#include <asm/desc.h>
20#include <asm/mmu_context.h>
21#include <asm/syscalls.h>
22
23#ifdef CONFIG_SMP
24static void flush_ldt(void *current_mm)
25{
26 if (current->active_mm == current_mm)
27 load_LDT(¤t->active_mm->context);
28}
29#endif
30
31static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
32{
33 void *oldldt, *newldt;
34 int oldsize;
35
36 if (mincount <= pc->size)
37 return 0;
38 oldsize = pc->size;
39 mincount = (mincount + (PAGE_SIZE / LDT_ENTRY_SIZE - 1)) &
40 (~(PAGE_SIZE / LDT_ENTRY_SIZE - 1));
41 if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE)
42 newldt = vmalloc(mincount * LDT_ENTRY_SIZE);
43 else
44 newldt = (void *)__get_free_page(GFP_KERNEL);
45
46 if (!newldt)
47 return -ENOMEM;
48
49 if (oldsize)
50 memcpy(newldt, pc->ldt, oldsize * LDT_ENTRY_SIZE);
51 oldldt = pc->ldt;
52 memset(newldt + oldsize * LDT_ENTRY_SIZE, 0,
53 (mincount - oldsize) * LDT_ENTRY_SIZE);
54
55 paravirt_alloc_ldt(newldt, mincount);
56
57#ifdef CONFIG_X86_64
58 /* CHECKME: Do we really need this ? */
59 wmb();
60#endif
61 pc->ldt = newldt;
62 wmb();
63 pc->size = mincount;
64 wmb();
65
66 if (reload) {
67#ifdef CONFIG_SMP
68 preempt_disable();
69 load_LDT(pc);
70 if (!cpumask_equal(mm_cpumask(current->mm),
71 cpumask_of(smp_processor_id())))
72 smp_call_function(flush_ldt, current->mm, 1);
73 preempt_enable();
74#else
75 load_LDT(pc);
76#endif
77 }
78 if (oldsize) {
79 paravirt_free_ldt(oldldt, oldsize);
80 if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
81 vfree(oldldt);
82 else
83 put_page(virt_to_page(oldldt));
84 }
85 return 0;
86}
87
88static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
89{
90 int err = alloc_ldt(new, old->size, 0);
91 int i;
92
93 if (err < 0)
94 return err;
95
96 for (i = 0; i < old->size; i++)
97 write_ldt_entry(new->ldt, i, old->ldt + i * LDT_ENTRY_SIZE);
98 return 0;
99}
100
101/*
102 * we do not have to muck with descriptors here, that is
103 * done in switch_mm() as needed.
104 */
105int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
106{
107 struct mm_struct *old_mm;
108 int retval = 0;
109
110 mutex_init(&mm->context.lock);
111 mm->context.size = 0;
112 old_mm = current->mm;
113 if (old_mm && old_mm->context.size > 0) {
114 mutex_lock(&old_mm->context.lock);
115 retval = copy_ldt(&mm->context, &old_mm->context);
116 mutex_unlock(&old_mm->context.lock);
117 }
118 return retval;
119}
120
121/*
122 * No need to lock the MM as we are the last user
123 *
124 * 64bit: Don't touch the LDT register - we're already in the next thread.
125 */
126void destroy_context(struct mm_struct *mm)
127{
128 if (mm->context.size) {
129#ifdef CONFIG_X86_32
130 /* CHECKME: Can this ever happen ? */
131 if (mm == current->active_mm)
132 clear_LDT();
133#endif
134 paravirt_free_ldt(mm->context.ldt, mm->context.size);
135 if (mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE)
136 vfree(mm->context.ldt);
137 else
138 put_page(virt_to_page(mm->context.ldt));
139 mm->context.size = 0;
140 }
141}
142
143static int read_ldt(void __user *ptr, unsigned long bytecount)
144{
145 int err;
146 unsigned long size;
147 struct mm_struct *mm = current->mm;
148
149 if (!mm->context.size)
150 return 0;
151 if (bytecount > LDT_ENTRY_SIZE * LDT_ENTRIES)
152 bytecount = LDT_ENTRY_SIZE * LDT_ENTRIES;
153
154 mutex_lock(&mm->context.lock);
155 size = mm->context.size * LDT_ENTRY_SIZE;
156 if (size > bytecount)
157 size = bytecount;
158
159 err = 0;
160 if (copy_to_user(ptr, mm->context.ldt, size))
161 err = -EFAULT;
162 mutex_unlock(&mm->context.lock);
163 if (err < 0)
164 goto error_return;
165 if (size != bytecount) {
166 /* zero-fill the rest */
167 if (clear_user(ptr + size, bytecount - size) != 0) {
168 err = -EFAULT;
169 goto error_return;
170 }
171 }
172 return bytecount;
173error_return:
174 return err;
175}
176
177static int read_default_ldt(void __user *ptr, unsigned long bytecount)
178{
179 /* CHECKME: Can we use _one_ random number ? */
180#ifdef CONFIG_X86_32
181 unsigned long size = 5 * sizeof(struct desc_struct);
182#else
183 unsigned long size = 128;
184#endif
185 if (bytecount > size)
186 bytecount = size;
187 if (clear_user(ptr, bytecount))
188 return -EFAULT;
189 return bytecount;
190}
191
192static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
193{
194 struct mm_struct *mm = current->mm;
195 struct desc_struct ldt;
196 int error;
197 struct user_desc ldt_info;
198
199 error = -EINVAL;
200 if (bytecount != sizeof(ldt_info))
201 goto out;
202 error = -EFAULT;
203 if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
204 goto out;
205
206 error = -EINVAL;
207 if (ldt_info.entry_number >= LDT_ENTRIES)
208 goto out;
209 if (ldt_info.contents == 3) {
210 if (oldmode)
211 goto out;
212 if (ldt_info.seg_not_present == 0)
213 goto out;
214 }
215
216 mutex_lock(&mm->context.lock);
217 if (ldt_info.entry_number >= mm->context.size) {
218 error = alloc_ldt(¤t->mm->context,
219 ldt_info.entry_number + 1, 1);
220 if (error < 0)
221 goto out_unlock;
222 }
223
224 /* Allow LDTs to be cleared by the user. */
225 if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
226 if (oldmode || LDT_empty(&ldt_info)) {
227 memset(&ldt, 0, sizeof(ldt));
228 goto install;
229 }
230 }
231
232 fill_ldt(&ldt, &ldt_info);
233 if (oldmode)
234 ldt.avl = 0;
235
236 /* Install the new entry ... */
237install:
238 write_ldt_entry(mm->context.ldt, ldt_info.entry_number, &ldt);
239 error = 0;
240
241out_unlock:
242 mutex_unlock(&mm->context.lock);
243out:
244 return error;
245}
246
247asmlinkage int sys_modify_ldt(int func, void __user *ptr,
248 unsigned long bytecount)
249{
250 int ret = -ENOSYS;
251
252 switch (func) {
253 case 0:
254 ret = read_ldt(ptr, bytecount);
255 break;
256 case 1:
257 ret = write_ldt(ptr, bytecount, 1);
258 break;
259 case 2:
260 ret = read_default_ldt(ptr, bytecount);
261 break;
262 case 0x11:
263 ret = write_ldt(ptr, bytecount, 0);
264 break;
265 }
266 return ret;
267}