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Linux 3.11-rc3
[cris-mirror.git] / arch / s390 / lib / uaccess_pt.c
blob50ea137a2d3c296859b600c0ef861c07fcce5209
1 /*
2 * User access functions based on page table walks for enhanced
3 * system layout without hardware support.
4 *
5 * Copyright IBM Corp. 2006, 2012
6 * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
7 */
8
9 #include <linux/errno.h>
10 #include <linux/hardirq.h>
11 #include <linux/mm.h>
12 #include <linux/hugetlb.h>
13 #include <asm/uaccess.h>
14 #include <asm/futex.h>
15 #include "uaccess.h"
16
17 #ifndef CONFIG_64BIT
18 #define AHI "ahi"
19 #define SLR "slr"
20 #else
21 #define AHI "aghi"
22 #define SLR "slgr"
23 #endif
24
25 static size_t strnlen_kernel(size_t count, const char __user *src)
26 {
27 register unsigned long reg0 asm("0") = 0UL;
28 unsigned long tmp1, tmp2;
29
30 asm volatile(
31 " la %2,0(%1)\n"
32 " la %3,0(%0,%1)\n"
33 " "SLR" %0,%0\n"
34 "0: srst %3,%2\n"
35 " jo 0b\n"
36 " la %0,1(%3)\n" /* strnlen_kernel results includes \0 */
37 " "SLR" %0,%1\n"
38 "1:\n"
39 EX_TABLE(0b,1b)
40 : "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
41 : "d" (reg0) : "cc", "memory");
42 return count;
43 }
44
45 static size_t copy_in_kernel(size_t count, void __user *to,
46 const void __user *from)
47 {
48 unsigned long tmp1;
49
50 asm volatile(
51 " "AHI" %0,-1\n"
52 " jo 5f\n"
53 " bras %3,3f\n"
54 "0:"AHI" %0,257\n"
55 "1: mvc 0(1,%1),0(%2)\n"
56 " la %1,1(%1)\n"
57 " la %2,1(%2)\n"
58 " "AHI" %0,-1\n"
59 " jnz 1b\n"
60 " j 5f\n"
61 "2: mvc 0(256,%1),0(%2)\n"
62 " la %1,256(%1)\n"
63 " la %2,256(%2)\n"
64 "3:"AHI" %0,-256\n"
65 " jnm 2b\n"
66 "4: ex %0,1b-0b(%3)\n"
67 "5:"SLR" %0,%0\n"
68 "6:\n"
69 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
70 : "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
71 : : "cc", "memory");
72 return count;
73 }
74
75 /*
76 * Returns kernel address for user virtual address. If the returned address is
77 * >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occured and the address
78 * contains the (negative) exception code.
79 */
80 #ifdef CONFIG_64BIT
81 static unsigned long follow_table(struct mm_struct *mm,
82 unsigned long address, int write)
83 {
84 unsigned long *table = (unsigned long *)__pa(mm->pgd);
85
86 switch (mm->context.asce_bits & _ASCE_TYPE_MASK) {
87 case _ASCE_TYPE_REGION1:
88 table = table + ((address >> 53) & 0x7ff);
89 if (unlikely(*table & _REGION_ENTRY_INV))
90 return -0x39UL;
91 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
92 /* fallthrough */
93 case _ASCE_TYPE_REGION2:
94 table = table + ((address >> 42) & 0x7ff);
95 if (unlikely(*table & _REGION_ENTRY_INV))
96 return -0x3aUL;
97 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
98 /* fallthrough */
99 case _ASCE_TYPE_REGION3:
100 table = table + ((address >> 31) & 0x7ff);
101 if (unlikely(*table & _REGION_ENTRY_INV))
102 return -0x3bUL;
103 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
104 /* fallthrough */
105 case _ASCE_TYPE_SEGMENT:
106 table = table + ((address >> 20) & 0x7ff);
107 if (unlikely(*table & _SEGMENT_ENTRY_INV))
108 return -0x10UL;
109 if (unlikely(*table & _SEGMENT_ENTRY_LARGE)) {
110 if (write && (*table & _SEGMENT_ENTRY_RO))
111 return -0x04UL;
112 return (*table & _SEGMENT_ENTRY_ORIGIN_LARGE) +
113 (address & ~_SEGMENT_ENTRY_ORIGIN_LARGE);
114 }
115 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
116 }
117 table = table + ((address >> 12) & 0xff);
118 if (unlikely(*table & _PAGE_INVALID))
119 return -0x11UL;
120 if (write && (*table & _PAGE_RO))
121 return -0x04UL;
122 return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
123 }
124
125 #else /* CONFIG_64BIT */
126
127 static unsigned long follow_table(struct mm_struct *mm,
128 unsigned long address, int write)
129 {
130 unsigned long *table = (unsigned long *)__pa(mm->pgd);
131
132 table = table + ((address >> 20) & 0x7ff);
133 if (unlikely(*table & _SEGMENT_ENTRY_INV))
134 return -0x10UL;
135 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
136 table = table + ((address >> 12) & 0xff);
137 if (unlikely(*table & _PAGE_INVALID))
138 return -0x11UL;
139 if (write && (*table & _PAGE_RO))
140 return -0x04UL;
141 return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
142 }
143
144 #endif /* CONFIG_64BIT */
145
146 static __always_inline size_t __user_copy_pt(unsigned long uaddr, void *kptr,
147 size_t n, int write_user)
148 {
149 struct mm_struct *mm = current->mm;
150 unsigned long offset, done, size, kaddr;
151 void *from, *to;
152
153 done = 0;
154 retry:
155 spin_lock(&mm->page_table_lock);
156 do {
157 kaddr = follow_table(mm, uaddr, write_user);
158 if (IS_ERR_VALUE(kaddr))
159 goto fault;
160
161 offset = uaddr & ~PAGE_MASK;
162 size = min(n - done, PAGE_SIZE - offset);
163 if (write_user) {
164 to = (void *) kaddr;
165 from = kptr + done;
166 } else {
167 from = (void *) kaddr;
168 to = kptr + done;
169 }
170 memcpy(to, from, size);
171 done += size;
172 uaddr += size;
173 } while (done < n);
174 spin_unlock(&mm->page_table_lock);
175 return n - done;
176 fault:
177 spin_unlock(&mm->page_table_lock);
178 if (__handle_fault(uaddr, -kaddr, write_user))
179 return n - done;
180 goto retry;
181 }
182
183 /*
184 * Do DAT for user address by page table walk, return kernel address.
185 * This function needs to be called with current->mm->page_table_lock held.
186 */
187 static __always_inline unsigned long __dat_user_addr(unsigned long uaddr,
188 int write)
189 {
190 struct mm_struct *mm = current->mm;
191 unsigned long kaddr;
192 int rc;
193
194 retry:
195 kaddr = follow_table(mm, uaddr, write);
196 if (IS_ERR_VALUE(kaddr))
197 goto fault;
198
199 return kaddr;
200 fault:
201 spin_unlock(&mm->page_table_lock);
202 rc = __handle_fault(uaddr, -kaddr, write);
203 spin_lock(&mm->page_table_lock);
204 if (!rc)
205 goto retry;
206 return 0;
207 }
208
209 size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
210 {
211 size_t rc;
212
213 if (segment_eq(get_fs(), KERNEL_DS))
214 return copy_in_kernel(n, (void __user *) to, from);
215 rc = __user_copy_pt((unsigned long) from, to, n, 0);
216 if (unlikely(rc))
217 memset(to + n - rc, 0, rc);
218 return rc;
219 }
220
221 size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
222 {
223 if (segment_eq(get_fs(), KERNEL_DS))
224 return copy_in_kernel(n, to, (void __user *) from);
225 return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
226 }
227
228 static size_t clear_user_pt(size_t n, void __user *to)
229 {
230 void *zpage = (void *) empty_zero_page;
231 long done, size, ret;
232
233 done = 0;
234 do {
235 if (n - done > PAGE_SIZE)
236 size = PAGE_SIZE;
237 else
238 size = n - done;
239 if (segment_eq(get_fs(), KERNEL_DS))
240 ret = copy_in_kernel(n, to, (void __user *) zpage);
241 else
242 ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
243 done += size;
244 to += size;
245 if (ret)
246 return ret + n - done;
247 } while (done < n);
248 return 0;
249 }
250
251 static size_t strnlen_user_pt(size_t count, const char __user *src)
252 {
253 unsigned long uaddr = (unsigned long) src;
254 struct mm_struct *mm = current->mm;
255 unsigned long offset, done, len, kaddr;
256 size_t len_str;
257
258 if (unlikely(!count))
259 return 0;
260 if (segment_eq(get_fs(), KERNEL_DS))
261 return strnlen_kernel(count, src);
262 done = 0;
263 retry:
264 spin_lock(&mm->page_table_lock);
265 do {
266 kaddr = follow_table(mm, uaddr, 0);
267 if (IS_ERR_VALUE(kaddr))
268 goto fault;
269
270 offset = uaddr & ~PAGE_MASK;
271 len = min(count - done, PAGE_SIZE - offset);
272 len_str = strnlen((char *) kaddr, len);
273 done += len_str;
274 uaddr += len_str;
275 } while ((len_str == len) && (done < count));
276 spin_unlock(&mm->page_table_lock);
277 return done + 1;
278 fault:
279 spin_unlock(&mm->page_table_lock);
280 if (__handle_fault(uaddr, -kaddr, 0))
281 return 0;
282 goto retry;
283 }
284
285 static size_t strncpy_from_user_pt(size_t count, const char __user *src,
286 char *dst)
287 {
288 size_t done, len, offset, len_str;
289
290 if (unlikely(!count))
291 return 0;
292 done = 0;
293 do {
294 offset = (size_t)src & ~PAGE_MASK;
295 len = min(count - done, PAGE_SIZE - offset);
296 if (segment_eq(get_fs(), KERNEL_DS)) {
297 if (copy_in_kernel(len, (void __user *) dst, src))
298 return -EFAULT;
299 } else {
300 if (__user_copy_pt((unsigned long) src, dst, len, 0))
301 return -EFAULT;
302 }
303 len_str = strnlen(dst, len);
304 done += len_str;
305 src += len_str;
306 dst += len_str;
307 } while ((len_str == len) && (done < count));
308 return done;
309 }
310
311 static size_t copy_in_user_pt(size_t n, void __user *to,
312 const void __user *from)
313 {
314 struct mm_struct *mm = current->mm;
315 unsigned long offset_max, uaddr, done, size, error_code;
316 unsigned long uaddr_from = (unsigned long) from;
317 unsigned long uaddr_to = (unsigned long) to;
318 unsigned long kaddr_to, kaddr_from;
319 int write_user;
320
321 if (segment_eq(get_fs(), KERNEL_DS))
322 return copy_in_kernel(n, to, from);
323 done = 0;
324 retry:
325 spin_lock(&mm->page_table_lock);
326 do {
327 write_user = 0;
328 uaddr = uaddr_from;
329 kaddr_from = follow_table(mm, uaddr_from, 0);
330 error_code = kaddr_from;
331 if (IS_ERR_VALUE(error_code))
332 goto fault;
333
334 write_user = 1;
335 uaddr = uaddr_to;
336 kaddr_to = follow_table(mm, uaddr_to, 1);
337 error_code = (unsigned long) kaddr_to;
338 if (IS_ERR_VALUE(error_code))
339 goto fault;
340
341 offset_max = max(uaddr_from & ~PAGE_MASK,
342 uaddr_to & ~PAGE_MASK);
343 size = min(n - done, PAGE_SIZE - offset_max);
344
345 memcpy((void *) kaddr_to, (void *) kaddr_from, size);
346 done += size;
347 uaddr_from += size;
348 uaddr_to += size;
349 } while (done < n);
350 spin_unlock(&mm->page_table_lock);
351 return n - done;
352 fault:
353 spin_unlock(&mm->page_table_lock);
354 if (__handle_fault(uaddr, -error_code, write_user))
355 return n - done;
356 goto retry;
357 }
358
359 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
360 asm volatile("0: l %1,0(%6)\n" \
361 "1: " insn \
362 "2: cs %1,%2,0(%6)\n" \
363 "3: jl 1b\n" \
364 " lhi %0,0\n" \
365 "4:\n" \
366 EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
367 : "=d" (ret), "=&d" (oldval), "=&d" (newval), \
368 "=m" (*uaddr) \
369 : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
370 "m" (*uaddr) : "cc" );
371
372 static int __futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
373 {
374 int oldval = 0, newval, ret;
375
376 switch (op) {
377 case FUTEX_OP_SET:
378 __futex_atomic_op("lr %2,%5\n",
379 ret, oldval, newval, uaddr, oparg);
380 break;
381 case FUTEX_OP_ADD:
382 __futex_atomic_op("lr %2,%1\nar %2,%5\n",
383 ret, oldval, newval, uaddr, oparg);
384 break;
385 case FUTEX_OP_OR:
386 __futex_atomic_op("lr %2,%1\nor %2,%5\n",
387 ret, oldval, newval, uaddr, oparg);
388 break;
389 case FUTEX_OP_ANDN:
390 __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
391 ret, oldval, newval, uaddr, oparg);
392 break;
393 case FUTEX_OP_XOR:
394 __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
395 ret, oldval, newval, uaddr, oparg);
396 break;
397 default:
398 ret = -ENOSYS;
399 }
400 if (ret == 0)
401 *old = oldval;
402 return ret;
403 }
404
405 int futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
406 {
407 int ret;
408
409 if (segment_eq(get_fs(), KERNEL_DS))
410 return __futex_atomic_op_pt(op, uaddr, oparg, old);
411 spin_lock(&current->mm->page_table_lock);
412 uaddr = (u32 __force __user *)
413 __dat_user_addr((__force unsigned long) uaddr, 1);
414 if (!uaddr) {
415 spin_unlock(&current->mm->page_table_lock);
416 return -EFAULT;
417 }
418 get_page(virt_to_page(uaddr));
419 spin_unlock(&current->mm->page_table_lock);
420 ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
421 put_page(virt_to_page(uaddr));
422 return ret;
423 }
424
425 static int __futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
426 u32 oldval, u32 newval)
427 {
428 int ret;
429
430 asm volatile("0: cs %1,%4,0(%5)\n"
431 "1: la %0,0\n"
432 "2:\n"
433 EX_TABLE(0b,2b) EX_TABLE(1b,2b)
434 : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
435 : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
436 : "cc", "memory" );
437 *uval = oldval;
438 return ret;
439 }
440
441 int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
442 u32 oldval, u32 newval)
443 {
444 int ret;
445
446 if (segment_eq(get_fs(), KERNEL_DS))
447 return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
448 spin_lock(&current->mm->page_table_lock);
449 uaddr = (u32 __force __user *)
450 __dat_user_addr((__force unsigned long) uaddr, 1);
451 if (!uaddr) {
452 spin_unlock(&current->mm->page_table_lock);
453 return -EFAULT;
454 }
455 get_page(virt_to_page(uaddr));
456 spin_unlock(&current->mm->page_table_lock);
457 ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
458 put_page(virt_to_page(uaddr));
459 return ret;
460 }
461
462 struct uaccess_ops uaccess_pt = {
463 .copy_from_user = copy_from_user_pt,
464 .copy_from_user_small = copy_from_user_pt,
465 .copy_to_user = copy_to_user_pt,
466 .copy_to_user_small = copy_to_user_pt,
467 .copy_in_user = copy_in_user_pt,
468 .clear_user = clear_user_pt,
469 .strnlen_user = strnlen_user_pt,
470 .strncpy_from_user = strncpy_from_user_pt,
471 .futex_atomic_op = futex_atomic_op_pt,
472 .futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
473 };
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