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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
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}
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/system.h>
19#include <asm/ldt.h>
20#include <asm/desc.h>
21#include <asm/mmu_context.h>
22#include <asm/syscalls.h>
23
24#ifdef CONFIG_SMP
25static void flush_ldt(void *current_mm)
26{
27 if (current->active_mm == current_mm)
28 load_LDT(¤t->active_mm->context);
29}
30#endif
31
32static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
33{
34 void *oldldt, *newldt;
35 int oldsize;
36
37 if (mincount <= pc->size)
38 return 0;
39 oldsize = pc->size;
40 mincount = (mincount + (PAGE_SIZE / LDT_ENTRY_SIZE - 1)) &
41 (~(PAGE_SIZE / LDT_ENTRY_SIZE - 1));
42 if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE)
43 newldt = vmalloc(mincount * LDT_ENTRY_SIZE);
44 else
45 newldt = (void *)__get_free_page(GFP_KERNEL);
46
47 if (!newldt)
48 return -ENOMEM;
49
50 if (oldsize)
51 memcpy(newldt, pc->ldt, oldsize * LDT_ENTRY_SIZE);
52 oldldt = pc->ldt;
53 memset(newldt + oldsize * LDT_ENTRY_SIZE, 0,
54 (mincount - oldsize) * LDT_ENTRY_SIZE);
55
56 paravirt_alloc_ldt(newldt, mincount);
57
58#ifdef CONFIG_X86_64
59 /* CHECKME: Do we really need this ? */
60 wmb();
61#endif
62 pc->ldt = newldt;
63 wmb();
64 pc->size = mincount;
65 wmb();
66
67 if (reload) {
68#ifdef CONFIG_SMP
69 preempt_disable();
70 load_LDT(pc);
71 if (!cpumask_equal(mm_cpumask(current->mm),
72 cpumask_of(smp_processor_id())))
73 smp_call_function(flush_ldt, current->mm, 1);
74 preempt_enable();
75#else
76 load_LDT(pc);
77#endif
78 }
79 if (oldsize) {
80 paravirt_free_ldt(oldldt, oldsize);
81 if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
82 vfree(oldldt);
83 else
84 put_page(virt_to_page(oldldt));
85 }
86 return 0;
87}
88
89static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
90{
91 int err = alloc_ldt(new, old->size, 0);
92 int i;
93
94 if (err < 0)
95 return err;
96
97 for (i = 0; i < old->size; i++)
98 write_ldt_entry(new->ldt, i, old->ldt + i * LDT_ENTRY_SIZE);
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 */
106int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
107{
108 struct mm_struct *old_mm;
109 int retval = 0;
110
111 mutex_init(&mm->context.lock);
112 mm->context.size = 0;
113 old_mm = current->mm;
114 if (old_mm && old_mm->context.size > 0) {
115 mutex_lock(&old_mm->context.lock);
116 retval = copy_ldt(&mm->context, &old_mm->context);
117 mutex_unlock(&old_mm->context.lock);
118 }
119 return retval;
120}
121
122/*
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.
126 */
127void destroy_context(struct mm_struct *mm)
128{
129 if (mm->context.size) {
130#ifdef CONFIG_X86_32
131 /* CHECKME: Can this ever happen ? */
132 if (mm == current->active_mm)
133 clear_LDT();
134#endif
135 paravirt_free_ldt(mm->context.ldt, mm->context.size);
136 if (mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE)
137 vfree(mm->context.ldt);
138 else
139 put_page(virt_to_page(mm->context.ldt));
140 mm->context.size = 0;
141 }
142}
143
144static int read_ldt(void __user *ptr, unsigned long bytecount)
145{
146 int err;
147 unsigned long size;
148 struct mm_struct *mm = current->mm;
149
150 if (!mm->context.size)
151 return 0;
152 if (bytecount > LDT_ENTRY_SIZE * LDT_ENTRIES)
153 bytecount = LDT_ENTRY_SIZE * LDT_ENTRIES;
154
155 mutex_lock(&mm->context.lock);
156 size = mm->context.size * LDT_ENTRY_SIZE;
157 if (size > bytecount)
158 size = bytecount;
159
160 err = 0;
161 if (copy_to_user(ptr, mm->context.ldt, size))
162 err = -EFAULT;
163 mutex_unlock(&mm->context.lock);
164 if (err < 0)
165 goto error_return;
166 if (size != bytecount) {
167 /* zero-fill the rest */
168 if (clear_user(ptr + size, bytecount - size) != 0) {
169 err = -EFAULT;
170 goto error_return;
171 }
172 }
173 return bytecount;
174error_return:
175 return err;
176}
177
178static int read_default_ldt(void __user *ptr, unsigned long bytecount)
179{
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;
188 if (clear_user(ptr, bytecount))
189 return -EFAULT;
190 return bytecount;
191}
192
193static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
194{
195 struct mm_struct *mm = current->mm;
196 struct desc_struct ldt;
197 int error;
198 struct user_desc ldt_info;
199
200 error = -EINVAL;
201 if (bytecount != sizeof(ldt_info))
202 goto out;
203 error = -EFAULT;
204 if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
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
217 mutex_lock(&mm->context.lock);
218 if (ldt_info.entry_number >= mm->context.size) {
219 error = alloc_ldt(¤t->mm->context,
220 ldt_info.entry_number + 1, 1);
221 if (error < 0)
222 goto out_unlock;
223 }
224
225 /* Allow LDTs to be cleared by the user. */
226 if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
227 if (oldmode || LDT_empty(&ldt_info)) {
228 memset(&ldt, 0, sizeof(ldt));
229 goto install;
230 }
231 }
232
233 fill_ldt(&ldt, &ldt_info);
234 if (oldmode)
235 ldt.avl = 0;
236
237 /* Install the new entry ... */
238install:
239 write_ldt_entry(mm->context.ldt, ldt_info.entry_number, &ldt);
240 error = 0;
241
242out_unlock:
243 mutex_unlock(&mm->context.lock);
244out:
245 return error;
246}
247
248asmlinkage int sys_modify_ldt(int func, void __user *ptr,
249 unsigned long bytecount)
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}