Linux 4.13.16
[linux/fpc-iii.git] / arch / x86 / um / ldt.c
blob836a1eb5df436bdad88fe3b4ae59b512f9573b19
1 /*
2 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
6 #include <linux/mm.h>
7 #include <linux/sched.h>
8 #include <linux/slab.h>
9 #include <linux/uaccess.h>
10 #include <asm/unistd.h>
11 #include <os.h>
12 #include <skas.h>
13 #include <sysdep/tls.h>
15 static inline int modify_ldt (int func, void *ptr, unsigned long bytecount)
17 return syscall(__NR_modify_ldt, func, ptr, bytecount);
20 static long write_ldt_entry(struct mm_id *mm_idp, int func,
21 struct user_desc *desc, void **addr, int done)
23 long res;
24 void *stub_addr;
25 res = syscall_stub_data(mm_idp, (unsigned long *)desc,
26 (sizeof(*desc) + sizeof(long) - 1) &
27 ~(sizeof(long) - 1),
28 addr, &stub_addr);
29 if (!res) {
30 unsigned long args[] = { func,
31 (unsigned long)stub_addr,
32 sizeof(*desc),
33 0, 0, 0 };
34 res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
35 0, addr, done);
38 return res;
42 * In skas mode, we hold our own ldt data in UML.
43 * Thus, the code implementing sys_modify_ldt_skas
44 * is very similar to (and mostly stolen from) sys_modify_ldt
45 * for arch/i386/kernel/ldt.c
46 * The routines copied and modified in part are:
47 * - read_ldt
48 * - read_default_ldt
49 * - write_ldt
50 * - sys_modify_ldt_skas
53 static int read_ldt(void __user * ptr, unsigned long bytecount)
55 int i, err = 0;
56 unsigned long size;
57 uml_ldt_t *ldt = &current->mm->context.arch.ldt;
59 if (!ldt->entry_count)
60 goto out;
61 if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
62 bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
63 err = bytecount;
65 mutex_lock(&ldt->lock);
66 if (ldt->entry_count <= LDT_DIRECT_ENTRIES) {
67 size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
68 if (size > bytecount)
69 size = bytecount;
70 if (copy_to_user(ptr, ldt->u.entries, size))
71 err = -EFAULT;
72 bytecount -= size;
73 ptr += size;
75 else {
76 for (i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
77 i++) {
78 size = PAGE_SIZE;
79 if (size > bytecount)
80 size = bytecount;
81 if (copy_to_user(ptr, ldt->u.pages[i], size)) {
82 err = -EFAULT;
83 break;
85 bytecount -= size;
86 ptr += size;
89 mutex_unlock(&ldt->lock);
91 if (bytecount == 0 || err == -EFAULT)
92 goto out;
94 if (clear_user(ptr, bytecount))
95 err = -EFAULT;
97 out:
98 return err;
101 static int read_default_ldt(void __user * ptr, unsigned long bytecount)
103 int err;
105 if (bytecount > 5*LDT_ENTRY_SIZE)
106 bytecount = 5*LDT_ENTRY_SIZE;
108 err = bytecount;
110 * UML doesn't support lcall7 and lcall27.
111 * So, we don't really have a default ldt, but emulate
112 * an empty ldt of common host default ldt size.
114 if (clear_user(ptr, bytecount))
115 err = -EFAULT;
117 return err;
120 static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
122 uml_ldt_t *ldt = &current->mm->context.arch.ldt;
123 struct mm_id * mm_idp = &current->mm->context.id;
124 int i, err;
125 struct user_desc ldt_info;
126 struct ldt_entry entry0, *ldt_p;
127 void *addr = NULL;
129 err = -EINVAL;
130 if (bytecount != sizeof(ldt_info))
131 goto out;
132 err = -EFAULT;
133 if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
134 goto out;
136 err = -EINVAL;
137 if (ldt_info.entry_number >= LDT_ENTRIES)
138 goto out;
139 if (ldt_info.contents == 3) {
140 if (func == 1)
141 goto out;
142 if (ldt_info.seg_not_present == 0)
143 goto out;
146 mutex_lock(&ldt->lock);
148 err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
149 if (err)
150 goto out_unlock;
152 if (ldt_info.entry_number >= ldt->entry_count &&
153 ldt_info.entry_number >= LDT_DIRECT_ENTRIES) {
154 for (i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
155 i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
156 i++) {
157 if (i == 0)
158 memcpy(&entry0, ldt->u.entries,
159 sizeof(entry0));
160 ldt->u.pages[i] = (struct ldt_entry *)
161 __get_free_page(GFP_KERNEL|__GFP_ZERO);
162 if (!ldt->u.pages[i]) {
163 err = -ENOMEM;
164 /* Undo the change in host */
165 memset(&ldt_info, 0, sizeof(ldt_info));
166 write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
167 goto out_unlock;
169 if (i == 0) {
170 memcpy(ldt->u.pages[0], &entry0,
171 sizeof(entry0));
172 memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
173 sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
175 ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
178 if (ldt->entry_count <= ldt_info.entry_number)
179 ldt->entry_count = ldt_info.entry_number + 1;
181 if (ldt->entry_count <= LDT_DIRECT_ENTRIES)
182 ldt_p = ldt->u.entries + ldt_info.entry_number;
183 else
184 ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
185 ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
187 if (ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
188 (func == 1 || LDT_empty(&ldt_info))) {
189 ldt_p->a = 0;
190 ldt_p->b = 0;
192 else{
193 if (func == 1)
194 ldt_info.useable = 0;
195 ldt_p->a = LDT_entry_a(&ldt_info);
196 ldt_p->b = LDT_entry_b(&ldt_info);
198 err = 0;
200 out_unlock:
201 mutex_unlock(&ldt->lock);
202 out:
203 return err;
206 static long do_modify_ldt_skas(int func, void __user *ptr,
207 unsigned long bytecount)
209 int ret = -ENOSYS;
211 switch (func) {
212 case 0:
213 ret = read_ldt(ptr, bytecount);
214 break;
215 case 1:
216 case 0x11:
217 ret = write_ldt(ptr, bytecount, func);
218 break;
219 case 2:
220 ret = read_default_ldt(ptr, bytecount);
221 break;
223 return ret;
226 static DEFINE_SPINLOCK(host_ldt_lock);
227 static short dummy_list[9] = {0, -1};
228 static short * host_ldt_entries = NULL;
230 static void ldt_get_host_info(void)
232 long ret;
233 struct ldt_entry * ldt;
234 short *tmp;
235 int i, size, k, order;
237 spin_lock(&host_ldt_lock);
239 if (host_ldt_entries != NULL) {
240 spin_unlock(&host_ldt_lock);
241 return;
243 host_ldt_entries = dummy_list+1;
245 spin_unlock(&host_ldt_lock);
247 for (i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++)
250 ldt = (struct ldt_entry *)
251 __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
252 if (ldt == NULL) {
253 printk(KERN_ERR "ldt_get_host_info: couldn't allocate buffer "
254 "for host ldt\n");
255 return;
258 ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
259 if (ret < 0) {
260 printk(KERN_ERR "ldt_get_host_info: couldn't read host ldt\n");
261 goto out_free;
263 if (ret == 0) {
264 /* default_ldt is active, simply write an empty entry 0 */
265 host_ldt_entries = dummy_list;
266 goto out_free;
269 for (i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++) {
270 if (ldt[i].a != 0 || ldt[i].b != 0)
271 size++;
274 if (size < ARRAY_SIZE(dummy_list))
275 host_ldt_entries = dummy_list;
276 else {
277 size = (size + 1) * sizeof(dummy_list[0]);
278 tmp = kmalloc(size, GFP_KERNEL);
279 if (tmp == NULL) {
280 printk(KERN_ERR "ldt_get_host_info: couldn't allocate "
281 "host ldt list\n");
282 goto out_free;
284 host_ldt_entries = tmp;
287 for (i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++) {
288 if (ldt[i].a != 0 || ldt[i].b != 0)
289 host_ldt_entries[k++] = i;
291 host_ldt_entries[k] = -1;
293 out_free:
294 free_pages((unsigned long)ldt, order);
297 long init_new_ldt(struct mm_context *new_mm, struct mm_context *from_mm)
299 struct user_desc desc;
300 short * num_p;
301 int i;
302 long page, err=0;
303 void *addr = NULL;
306 mutex_init(&new_mm->arch.ldt.lock);
308 if (!from_mm) {
309 memset(&desc, 0, sizeof(desc));
311 * Now we try to retrieve info about the ldt, we
312 * inherited from the host. All ldt-entries found
313 * will be reset in the following loop
315 ldt_get_host_info();
316 for (num_p=host_ldt_entries; *num_p != -1; num_p++) {
317 desc.entry_number = *num_p;
318 err = write_ldt_entry(&new_mm->id, 1, &desc,
319 &addr, *(num_p + 1) == -1);
320 if (err)
321 break;
323 new_mm->arch.ldt.entry_count = 0;
325 goto out;
329 * Our local LDT is used to supply the data for
330 * modify_ldt(READLDT), if PTRACE_LDT isn't available,
331 * i.e., we have to use the stub for modify_ldt, which
332 * can't handle the big read buffer of up to 64kB.
334 mutex_lock(&from_mm->arch.ldt.lock);
335 if (from_mm->arch.ldt.entry_count <= LDT_DIRECT_ENTRIES)
336 memcpy(new_mm->arch.ldt.u.entries, from_mm->arch.ldt.u.entries,
337 sizeof(new_mm->arch.ldt.u.entries));
338 else {
339 i = from_mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
340 while (i-->0) {
341 page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
342 if (!page) {
343 err = -ENOMEM;
344 break;
346 new_mm->arch.ldt.u.pages[i] =
347 (struct ldt_entry *) page;
348 memcpy(new_mm->arch.ldt.u.pages[i],
349 from_mm->arch.ldt.u.pages[i], PAGE_SIZE);
352 new_mm->arch.ldt.entry_count = from_mm->arch.ldt.entry_count;
353 mutex_unlock(&from_mm->arch.ldt.lock);
355 out:
356 return err;
360 void free_ldt(struct mm_context *mm)
362 int i;
364 if (mm->arch.ldt.entry_count > LDT_DIRECT_ENTRIES) {
365 i = mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
366 while (i-- > 0)
367 free_page((long) mm->arch.ldt.u.pages[i]);
369 mm->arch.ldt.entry_count = 0;
372 int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
374 return do_modify_ldt_skas(func, ptr, bytecount);