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Linux 2.6.28-rc5
[cris-mirror.git] / arch / s390 / lib / uaccess_pt.c
blobd66215b0fde9d8d932cd31a43b3dee2e283b3a4a
1 /*
2 * arch/s390/lib/uaccess_pt.c
3 *
4 * User access functions based on page table walks for enhanced
5 * system layout without hardware support.
6 *
7 * Copyright IBM Corp. 2006
8 * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
9 */
10
11 #include <linux/errno.h>
12 #include <linux/hardirq.h>
13 #include <linux/mm.h>
14 #include <asm/uaccess.h>
15 #include <asm/futex.h>
16 #include "uaccess.h"
17
18 static inline pte_t *follow_table(struct mm_struct *mm, unsigned long addr)
19 {
20 pgd_t *pgd;
21 pud_t *pud;
22 pmd_t *pmd;
23
24 pgd = pgd_offset(mm, addr);
25 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
26 return NULL;
27
28 pud = pud_offset(pgd, addr);
29 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
30 return NULL;
31
32 pmd = pmd_offset(pud, addr);
33 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
34 return NULL;
35
36 return pte_offset_map(pmd, addr);
37 }
38
39 static int __handle_fault(struct mm_struct *mm, unsigned long address,
40 int write_access)
41 {
42 struct vm_area_struct *vma;
43 int ret = -EFAULT;
44 int fault;
45
46 if (in_atomic())
47 return ret;
48 down_read(&mm->mmap_sem);
49 vma = find_vma(mm, address);
50 if (unlikely(!vma))
51 goto out;
52 if (unlikely(vma->vm_start > address)) {
53 if (!(vma->vm_flags & VM_GROWSDOWN))
54 goto out;
55 if (expand_stack(vma, address))
56 goto out;
57 }
58
59 if (!write_access) {
60 /* page not present, check vm flags */
61 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
62 goto out;
63 } else {
64 if (!(vma->vm_flags & VM_WRITE))
65 goto out;
66 }
67
68 survive:
69 fault = handle_mm_fault(mm, vma, address, write_access);
70 if (unlikely(fault & VM_FAULT_ERROR)) {
71 if (fault & VM_FAULT_OOM)
72 goto out_of_memory;
73 else if (fault & VM_FAULT_SIGBUS)
74 goto out_sigbus;
75 BUG();
76 }
77 if (fault & VM_FAULT_MAJOR)
78 current->maj_flt++;
79 else
80 current->min_flt++;
81 ret = 0;
82 out:
83 up_read(&mm->mmap_sem);
84 return ret;
85
86 out_of_memory:
87 up_read(&mm->mmap_sem);
88 if (is_global_init(current)) {
89 yield();
90 down_read(&mm->mmap_sem);
91 goto survive;
92 }
93 printk("VM: killing process %s\n", current->comm);
94 return ret;
95
96 out_sigbus:
97 up_read(&mm->mmap_sem);
98 current->thread.prot_addr = address;
99 current->thread.trap_no = 0x11;
100 force_sig(SIGBUS, current);
101 return ret;
102 }
103
104 static size_t __user_copy_pt(unsigned long uaddr, void *kptr,
105 size_t n, int write_user)
106 {
107 struct mm_struct *mm = current->mm;
108 unsigned long offset, pfn, done, size;
109 pte_t *pte;
110 void *from, *to;
111
112 done = 0;
113 retry:
114 spin_lock(&mm->page_table_lock);
115 do {
116 pte = follow_table(mm, uaddr);
117 if (!pte || !pte_present(*pte) ||
118 (write_user && !pte_write(*pte)))
119 goto fault;
120
121 pfn = pte_pfn(*pte);
122 if (!pfn_valid(pfn))
123 goto out;
124
125 offset = uaddr & (PAGE_SIZE - 1);
126 size = min(n - done, PAGE_SIZE - offset);
127 if (write_user) {
128 to = (void *)((pfn << PAGE_SHIFT) + offset);
129 from = kptr + done;
130 } else {
131 from = (void *)((pfn << PAGE_SHIFT) + offset);
132 to = kptr + done;
133 }
134 memcpy(to, from, size);
135 done += size;
136 uaddr += size;
137 } while (done < n);
138 out:
139 spin_unlock(&mm->page_table_lock);
140 return n - done;
141 fault:
142 spin_unlock(&mm->page_table_lock);
143 if (__handle_fault(mm, uaddr, write_user))
144 return n - done;
145 goto retry;
146 }
147
148 /*
149 * Do DAT for user address by page table walk, return kernel address.
150 * This function needs to be called with current->mm->page_table_lock held.
151 */
152 static unsigned long __dat_user_addr(unsigned long uaddr)
153 {
154 struct mm_struct *mm = current->mm;
155 unsigned long pfn, ret;
156 pte_t *pte;
157 int rc;
158
159 ret = 0;
160 retry:
161 pte = follow_table(mm, uaddr);
162 if (!pte || !pte_present(*pte))
163 goto fault;
164
165 pfn = pte_pfn(*pte);
166 if (!pfn_valid(pfn))
167 goto out;
168
169 ret = (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
170 out:
171 return ret;
172 fault:
173 spin_unlock(&mm->page_table_lock);
174 rc = __handle_fault(mm, uaddr, 0);
175 spin_lock(&mm->page_table_lock);
176 if (rc)
177 goto out;
178 goto retry;
179 }
180
181 size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
182 {
183 size_t rc;
184
185 if (segment_eq(get_fs(), KERNEL_DS)) {
186 memcpy(to, (void __kernel __force *) from, n);
187 return 0;
188 }
189 rc = __user_copy_pt((unsigned long) from, to, n, 0);
190 if (unlikely(rc))
191 memset(to + n - rc, 0, rc);
192 return rc;
193 }
194
195 size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
196 {
197 if (segment_eq(get_fs(), KERNEL_DS)) {
198 memcpy((void __kernel __force *) to, from, n);
199 return 0;
200 }
201 return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
202 }
203
204 static size_t clear_user_pt(size_t n, void __user *to)
205 {
206 long done, size, ret;
207
208 if (segment_eq(get_fs(), KERNEL_DS)) {
209 memset((void __kernel __force *) to, 0, n);
210 return 0;
211 }
212 done = 0;
213 do {
214 if (n - done > PAGE_SIZE)
215 size = PAGE_SIZE;
216 else
217 size = n - done;
218 ret = __user_copy_pt((unsigned long) to + done,
219 &empty_zero_page, size, 1);
220 done += size;
221 if (ret)
222 return ret + n - done;
223 } while (done < n);
224 return 0;
225 }
226
227 static size_t strnlen_user_pt(size_t count, const char __user *src)
228 {
229 char *addr;
230 unsigned long uaddr = (unsigned long) src;
231 struct mm_struct *mm = current->mm;
232 unsigned long offset, pfn, done, len;
233 pte_t *pte;
234 size_t len_str;
235
236 if (segment_eq(get_fs(), KERNEL_DS))
237 return strnlen((const char __kernel __force *) src, count) + 1;
238 done = 0;
239 retry:
240 spin_lock(&mm->page_table_lock);
241 do {
242 pte = follow_table(mm, uaddr);
243 if (!pte || !pte_present(*pte))
244 goto fault;
245
246 pfn = pte_pfn(*pte);
247 if (!pfn_valid(pfn)) {
248 done = -1;
249 goto out;
250 }
251
252 offset = uaddr & (PAGE_SIZE-1);
253 addr = (char *)(pfn << PAGE_SHIFT) + offset;
254 len = min(count - done, PAGE_SIZE - offset);
255 len_str = strnlen(addr, len);
256 done += len_str;
257 uaddr += len_str;
258 } while ((len_str == len) && (done < count));
259 out:
260 spin_unlock(&mm->page_table_lock);
261 return done + 1;
262 fault:
263 spin_unlock(&mm->page_table_lock);
264 if (__handle_fault(mm, uaddr, 0)) {
265 return 0;
266 }
267 goto retry;
268 }
269
270 static size_t strncpy_from_user_pt(size_t count, const char __user *src,
271 char *dst)
272 {
273 size_t n = strnlen_user_pt(count, src);
274
275 if (!n)
276 return -EFAULT;
277 if (n > count)
278 n = count;
279 if (segment_eq(get_fs(), KERNEL_DS)) {
280 memcpy(dst, (const char __kernel __force *) src, n);
281 if (dst[n-1] == '\0')
282 return n-1;
283 else
284 return n;
285 }
286 if (__user_copy_pt((unsigned long) src, dst, n, 0))
287 return -EFAULT;
288 if (dst[n-1] == '\0')
289 return n-1;
290 else
291 return n;
292 }
293
294 static size_t copy_in_user_pt(size_t n, void __user *to,
295 const void __user *from)
296 {
297 struct mm_struct *mm = current->mm;
298 unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
299 uaddr, done, size;
300 unsigned long uaddr_from = (unsigned long) from;
301 unsigned long uaddr_to = (unsigned long) to;
302 pte_t *pte_from, *pte_to;
303 int write_user;
304
305 if (segment_eq(get_fs(), KERNEL_DS)) {
306 memcpy((void __force *) to, (void __force *) from, n);
307 return 0;
308 }
309 done = 0;
310 retry:
311 spin_lock(&mm->page_table_lock);
312 do {
313 pte_from = follow_table(mm, uaddr_from);
314 if (!pte_from || !pte_present(*pte_from)) {
315 uaddr = uaddr_from;
316 write_user = 0;
317 goto fault;
318 }
319
320 pte_to = follow_table(mm, uaddr_to);
321 if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) {
322 uaddr = uaddr_to;
323 write_user = 1;
324 goto fault;
325 }
326
327 pfn_from = pte_pfn(*pte_from);
328 if (!pfn_valid(pfn_from))
329 goto out;
330 pfn_to = pte_pfn(*pte_to);
331 if (!pfn_valid(pfn_to))
332 goto out;
333
334 offset_from = uaddr_from & (PAGE_SIZE-1);
335 offset_to = uaddr_from & (PAGE_SIZE-1);
336 offset_max = max(offset_from, offset_to);
337 size = min(n - done, PAGE_SIZE - offset_max);
338
339 memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
340 (void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
341 done += size;
342 uaddr_from += size;
343 uaddr_to += size;
344 } while (done < n);
345 out:
346 spin_unlock(&mm->page_table_lock);
347 return n - done;
348 fault:
349 spin_unlock(&mm->page_table_lock);
350 if (__handle_fault(mm, uaddr, write_user))
351 return n - done;
352 goto retry;
353 }
354
355 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
356 asm volatile("0: l %1,0(%6)\n" \
357 "1: " insn \
358 "2: cs %1,%2,0(%6)\n" \
359 "3: jl 1b\n" \
360 " lhi %0,0\n" \
361 "4:\n" \
362 EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
363 : "=d" (ret), "=&d" (oldval), "=&d" (newval), \
364 "=m" (*uaddr) \
365 : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
366 "m" (*uaddr) : "cc" );
367
368 static int __futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
369 {
370 int oldval = 0, newval, ret;
371
372 switch (op) {
373 case FUTEX_OP_SET:
374 __futex_atomic_op("lr %2,%5\n",
375 ret, oldval, newval, uaddr, oparg);
376 break;
377 case FUTEX_OP_ADD:
378 __futex_atomic_op("lr %2,%1\nar %2,%5\n",
379 ret, oldval, newval, uaddr, oparg);
380 break;
381 case FUTEX_OP_OR:
382 __futex_atomic_op("lr %2,%1\nor %2,%5\n",
383 ret, oldval, newval, uaddr, oparg);
384 break;
385 case FUTEX_OP_ANDN:
386 __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
387 ret, oldval, newval, uaddr, oparg);
388 break;
389 case FUTEX_OP_XOR:
390 __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
391 ret, oldval, newval, uaddr, oparg);
392 break;
393 default:
394 ret = -ENOSYS;
395 }
396 if (ret == 0)
397 *old = oldval;
398 return ret;
399 }
400
401 int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
402 {
403 int ret;
404
405 if (segment_eq(get_fs(), KERNEL_DS))
406 return __futex_atomic_op_pt(op, uaddr, oparg, old);
407 spin_lock(&current->mm->page_table_lock);
408 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
409 if (!uaddr) {
410 spin_unlock(&current->mm->page_table_lock);
411 return -EFAULT;
412 }
413 get_page(virt_to_page(uaddr));
414 spin_unlock(&current->mm->page_table_lock);
415 ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
416 put_page(virt_to_page(uaddr));
417 return ret;
418 }
419
420 static int __futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
421 {
422 int ret;
423
424 asm volatile("0: cs %1,%4,0(%5)\n"
425 "1: lr %0,%1\n"
426 "2:\n"
427 EX_TABLE(0b,2b) EX_TABLE(1b,2b)
428 : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
429 : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
430 : "cc", "memory" );
431 return ret;
432 }
433
434 int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
435 {
436 int ret;
437
438 if (segment_eq(get_fs(), KERNEL_DS))
439 return __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
440 spin_lock(&current->mm->page_table_lock);
441 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
442 if (!uaddr) {
443 spin_unlock(&current->mm->page_table_lock);
444 return -EFAULT;
445 }
446 get_page(virt_to_page(uaddr));
447 spin_unlock(&current->mm->page_table_lock);
448 ret = __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
449 put_page(virt_to_page(uaddr));
450 return ret;
451 }
452
453 struct uaccess_ops uaccess_pt = {
454 .copy_from_user = copy_from_user_pt,
455 .copy_from_user_small = copy_from_user_pt,
456 .copy_to_user = copy_to_user_pt,
457 .copy_to_user_small = copy_to_user_pt,
458 .copy_in_user = copy_in_user_pt,
459 .clear_user = clear_user_pt,
460 .strnlen_user = strnlen_user_pt,
461 .strncpy_from_user = strncpy_from_user_pt,
462 .futex_atomic_op = futex_atomic_op_pt,
463 .futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
464 };
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