Line data Source code
1 : /*
2 : * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 : * Licensed under the GPL
4 : */
5 :
6 : #include <linux/mm.h>
7 : #include <linux/sched.h>
8 : #include <linux/slab.h>
9 : #include <linux/syscalls.h>
10 : #include <linux/uaccess.h>
11 : #include <asm/unistd.h>
12 : #include <os.h>
13 : #include <skas.h>
14 : #include <sysdep/tls.h>
15 :
16 : static inline int modify_ldt (int func, void *ptr, unsigned long bytecount)
17 : {
18 0 : return syscall(__NR_modify_ldt, func, ptr, bytecount);
19 : }
20 :
21 0 : static long write_ldt_entry(struct mm_id *mm_idp, int func,
22 : struct user_desc *desc, void **addr, int done)
23 : {
24 : long res;
25 : void *stub_addr;
26 :
27 : BUILD_BUG_ON(sizeof(*desc) % sizeof(long));
28 :
29 0 : res = syscall_stub_data(mm_idp, (unsigned long *)desc,
30 : sizeof(*desc) / sizeof(long),
31 : addr, &stub_addr);
32 0 : if (!res) {
33 0 : unsigned long args[] = { func,
34 0 : (unsigned long)stub_addr,
35 : sizeof(*desc),
36 : 0, 0, 0 };
37 0 : res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
38 : 0, addr, done);
39 : }
40 :
41 0 : return res;
42 : }
43 :
44 : /*
45 : * In skas mode, we hold our own ldt data in UML.
46 : * Thus, the code implementing sys_modify_ldt_skas
47 : * is very similar to (and mostly stolen from) sys_modify_ldt
48 : * for arch/i386/kernel/ldt.c
49 : * The routines copied and modified in part are:
50 : * - read_ldt
51 : * - read_default_ldt
52 : * - write_ldt
53 : * - sys_modify_ldt_skas
54 : */
55 :
56 0 : static int read_ldt(void __user * ptr, unsigned long bytecount)
57 : {
58 0 : int i, err = 0;
59 : unsigned long size;
60 0 : uml_ldt_t *ldt = ¤t->mm->context.arch.ldt;
61 :
62 0 : if (!ldt->entry_count)
63 : goto out;
64 0 : if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
65 0 : bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
66 0 : err = bytecount;
67 :
68 0 : mutex_lock(&ldt->lock);
69 0 : if (ldt->entry_count <= LDT_DIRECT_ENTRIES) {
70 0 : size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
71 0 : if (size > bytecount)
72 0 : size = bytecount;
73 0 : if (copy_to_user(ptr, ldt->u.entries, size))
74 0 : err = -EFAULT;
75 0 : bytecount -= size;
76 0 : ptr += size;
77 : }
78 : else {
79 0 : for (i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
80 0 : i++) {
81 0 : size = PAGE_SIZE;
82 0 : if (size > bytecount)
83 0 : size = bytecount;
84 0 : if (copy_to_user(ptr, ldt->u.pages[i], size)) {
85 : err = -EFAULT;
86 : break;
87 : }
88 0 : bytecount -= size;
89 0 : ptr += size;
90 : }
91 : }
92 0 : mutex_unlock(&ldt->lock);
93 :
94 0 : if (bytecount == 0 || err == -EFAULT)
95 : goto out;
96 :
97 0 : if (clear_user(ptr, bytecount))
98 0 : err = -EFAULT;
99 :
100 : out:
101 0 : return err;
102 : }
103 :
104 : static int read_default_ldt(void __user * ptr, unsigned long bytecount)
105 : {
106 : int err;
107 :
108 0 : if (bytecount > 5*LDT_ENTRY_SIZE)
109 0 : bytecount = 5*LDT_ENTRY_SIZE;
110 :
111 0 : err = bytecount;
112 : /*
113 : * UML doesn't support lcall7 and lcall27.
114 : * So, we don't really have a default ldt, but emulate
115 : * an empty ldt of common host default ldt size.
116 : */
117 0 : if (clear_user(ptr, bytecount))
118 0 : err = -EFAULT;
119 :
120 : return err;
121 : }
122 :
123 0 : static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
124 : {
125 0 : uml_ldt_t *ldt = ¤t->mm->context.arch.ldt;
126 0 : struct mm_id * mm_idp = ¤t->mm->context.id;
127 : int i, err;
128 : struct user_desc ldt_info;
129 : struct ldt_entry entry0, *ldt_p;
130 0 : void *addr = NULL;
131 :
132 0 : err = -EINVAL;
133 0 : if (bytecount != sizeof(ldt_info))
134 : goto out;
135 0 : err = -EFAULT;
136 0 : if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
137 : goto out;
138 :
139 0 : err = -EINVAL;
140 0 : if (ldt_info.entry_number >= LDT_ENTRIES)
141 : goto out;
142 0 : if (ldt_info.contents == 3) {
143 0 : if (func == 1)
144 : goto out;
145 0 : if (ldt_info.seg_not_present == 0)
146 : goto out;
147 : }
148 :
149 0 : mutex_lock(&ldt->lock);
150 :
151 0 : err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
152 0 : if (err)
153 : goto out_unlock;
154 :
155 0 : if (ldt_info.entry_number >= ldt->entry_count &&
156 : ldt_info.entry_number >= LDT_DIRECT_ENTRIES) {
157 0 : for (i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
158 0 : i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
159 0 : i++) {
160 0 : if (i == 0)
161 0 : memcpy(&entry0, ldt->u.entries,
162 : sizeof(entry0));
163 0 : ldt->u.pages[i] = (struct ldt_entry *)
164 0 : __get_free_page(GFP_KERNEL|__GFP_ZERO);
165 0 : if (!ldt->u.pages[i]) {
166 0 : err = -ENOMEM;
167 : /* Undo the change in host */
168 0 : memset(&ldt_info, 0, sizeof(ldt_info));
169 0 : write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
170 0 : goto out_unlock;
171 : }
172 0 : if (i == 0) {
173 0 : memcpy(ldt->u.pages[0], &entry0,
174 : sizeof(entry0));
175 0 : memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
176 : sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
177 : }
178 0 : ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
179 : }
180 : }
181 0 : if (ldt->entry_count <= ldt_info.entry_number)
182 0 : ldt->entry_count = ldt_info.entry_number + 1;
183 :
184 0 : if (ldt->entry_count <= LDT_DIRECT_ENTRIES)
185 0 : ldt_p = ldt->u.entries + ldt_info.entry_number;
186 : else
187 0 : ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
188 0 : ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
189 :
190 0 : if (ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
191 0 : (func == 1 || LDT_empty(&ldt_info))) {
192 0 : ldt_p->a = 0;
193 0 : ldt_p->b = 0;
194 : }
195 : else{
196 0 : if (func == 1)
197 0 : ldt_info.useable = 0;
198 0 : ldt_p->a = LDT_entry_a(&ldt_info);
199 0 : ldt_p->b = LDT_entry_b(&ldt_info);
200 : }
201 : err = 0;
202 :
203 : out_unlock:
204 0 : mutex_unlock(&ldt->lock);
205 : out:
206 0 : return err;
207 : }
208 :
209 0 : static long do_modify_ldt_skas(int func, void __user *ptr,
210 : unsigned long bytecount)
211 : {
212 0 : int ret = -ENOSYS;
213 :
214 0 : switch (func) {
215 : case 0:
216 0 : ret = read_ldt(ptr, bytecount);
217 0 : break;
218 : case 1:
219 : case 0x11:
220 0 : ret = write_ldt(ptr, bytecount, func);
221 0 : break;
222 : case 2:
223 : ret = read_default_ldt(ptr, bytecount);
224 : break;
225 : }
226 0 : return ret;
227 : }
228 :
229 : static DEFINE_SPINLOCK(host_ldt_lock);
230 : static short dummy_list[9] = {0, -1};
231 : static short * host_ldt_entries = NULL;
232 :
233 0 : static void ldt_get_host_info(void)
234 : {
235 : long ret;
236 : struct ldt_entry * ldt;
237 : short *tmp;
238 : int i, size, k, order;
239 :
240 0 : spin_lock(&host_ldt_lock);
241 :
242 0 : if (host_ldt_entries != NULL) {
243 : spin_unlock(&host_ldt_lock);
244 : return;
245 : }
246 0 : host_ldt_entries = dummy_list+1;
247 :
248 0 : spin_unlock(&host_ldt_lock);
249 :
250 0 : for (i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++)
251 : ;
252 :
253 0 : ldt = (struct ldt_entry *)
254 0 : __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
255 0 : if (ldt == NULL) {
256 0 : printk(KERN_ERR "ldt_get_host_info: couldn't allocate buffer "
257 : "for host ldt\n");
258 0 : return;
259 : }
260 :
261 0 : ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
262 0 : if (ret < 0) {
263 0 : printk(KERN_ERR "ldt_get_host_info: couldn't read host ldt\n");
264 0 : goto out_free;
265 : }
266 0 : if (ret == 0) {
267 : /* default_ldt is active, simply write an empty entry 0 */
268 0 : host_ldt_entries = dummy_list;
269 0 : goto out_free;
270 : }
271 :
272 0 : for (i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++) {
273 0 : if (ldt[i].a != 0 || ldt[i].b != 0)
274 0 : size++;
275 : }
276 :
277 0 : if (size < ARRAY_SIZE(dummy_list))
278 0 : host_ldt_entries = dummy_list;
279 : else {
280 0 : size = (size + 1) * sizeof(dummy_list[0]);
281 0 : tmp = kmalloc(size, GFP_KERNEL);
282 0 : if (tmp == NULL) {
283 0 : printk(KERN_ERR "ldt_get_host_info: couldn't allocate "
284 : "host ldt list\n");
285 0 : goto out_free;
286 : }
287 0 : host_ldt_entries = tmp;
288 : }
289 :
290 0 : for (i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++) {
291 0 : if (ldt[i].a != 0 || ldt[i].b != 0)
292 0 : host_ldt_entries[k++] = i;
293 : }
294 0 : host_ldt_entries[k] = -1;
295 :
296 : out_free:
297 0 : free_pages((unsigned long)ldt, order);
298 : }
299 :
300 0 : long init_new_ldt(struct mm_context *new_mm, struct mm_context *from_mm)
301 : {
302 : struct user_desc desc;
303 : short * num_p;
304 : int i;
305 0 : long page, err=0;
306 0 : void *addr = NULL;
307 :
308 :
309 0 : mutex_init(&new_mm->arch.ldt.lock);
310 :
311 0 : if (!from_mm) {
312 0 : memset(&desc, 0, sizeof(desc));
313 : /*
314 : * Now we try to retrieve info about the ldt, we
315 : * inherited from the host. All ldt-entries found
316 : * will be reset in the following loop
317 : */
318 0 : ldt_get_host_info();
319 0 : for (num_p=host_ldt_entries; *num_p != -1; num_p++) {
320 0 : desc.entry_number = *num_p;
321 0 : err = write_ldt_entry(&new_mm->id, 1, &desc,
322 0 : &addr, *(num_p + 1) == -1);
323 0 : if (err)
324 : break;
325 : }
326 0 : new_mm->arch.ldt.entry_count = 0;
327 :
328 0 : goto out;
329 : }
330 :
331 : /*
332 : * Our local LDT is used to supply the data for
333 : * modify_ldt(READLDT), if PTRACE_LDT isn't available,
334 : * i.e., we have to use the stub for modify_ldt, which
335 : * can't handle the big read buffer of up to 64kB.
336 : */
337 0 : mutex_lock(&from_mm->arch.ldt.lock);
338 0 : if (from_mm->arch.ldt.entry_count <= LDT_DIRECT_ENTRIES)
339 0 : memcpy(new_mm->arch.ldt.u.entries, from_mm->arch.ldt.u.entries,
340 : sizeof(new_mm->arch.ldt.u.entries));
341 : else {
342 0 : i = from_mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
343 0 : while (i-->0) {
344 0 : page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
345 0 : if (!page) {
346 : err = -ENOMEM;
347 : break;
348 : }
349 0 : new_mm->arch.ldt.u.pages[i] =
350 0 : (struct ldt_entry *) page;
351 0 : memcpy(new_mm->arch.ldt.u.pages[i],
352 0 : from_mm->arch.ldt.u.pages[i], PAGE_SIZE);
353 : }
354 : }
355 0 : new_mm->arch.ldt.entry_count = from_mm->arch.ldt.entry_count;
356 0 : mutex_unlock(&from_mm->arch.ldt.lock);
357 :
358 : out:
359 0 : return err;
360 : }
361 :
362 :
363 0 : void free_ldt(struct mm_context *mm)
364 : {
365 : int i;
366 :
367 0 : if (mm->arch.ldt.entry_count > LDT_DIRECT_ENTRIES) {
368 0 : i = mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
369 0 : while (i-- > 0)
370 0 : free_page((long) mm->arch.ldt.u.pages[i]);
371 : }
372 0 : mm->arch.ldt.entry_count = 0;
373 0 : }
374 :
375 0 : SYSCALL_DEFINE3(modify_ldt, int , func , void __user * , ptr ,
376 : unsigned long , bytecount)
377 : {
378 : /* See non-um modify_ldt() for why we do this cast */
379 0 : return (unsigned int)do_modify_ldt_skas(func, ptr, bytecount);
380 : }
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