b3cebcd52f5c11a2d0ac50c4980c131c4a94aee7
[linux-3.10.git] / arch / s390 / lib / uaccess_pt.c
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 (pte_t *) 0x3a;
27
28         pud = pud_offset(pgd, addr);
29         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
30                 return (pte_t *) 0x3b;
31
32         pmd = pmd_offset(pud, addr);
33         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
34                 return (pte_t *) 0x10;
35
36         return pte_offset_map(pmd, addr);
37 }
38
39 static __always_inline size_t __user_copy_pt(unsigned long uaddr, void *kptr,
40                                              size_t n, int write_user)
41 {
42         struct mm_struct *mm = current->mm;
43         unsigned long offset, pfn, done, size;
44         pte_t *pte;
45         void *from, *to;
46
47         done = 0;
48 retry:
49         spin_lock(&mm->page_table_lock);
50         do {
51                 pte = follow_table(mm, uaddr);
52                 if ((unsigned long) pte < 0x1000)
53                         goto fault;
54                 if (!pte_present(*pte)) {
55                         pte = (pte_t *) 0x11;
56                         goto fault;
57                 } else if (write_user && !pte_write(*pte)) {
58                         pte = (pte_t *) 0x04;
59                         goto fault;
60                 }
61
62                 pfn = pte_pfn(*pte);
63                 offset = uaddr & (PAGE_SIZE - 1);
64                 size = min(n - done, PAGE_SIZE - offset);
65                 if (write_user) {
66                         to = (void *)((pfn << PAGE_SHIFT) + offset);
67                         from = kptr + done;
68                 } else {
69                         from = (void *)((pfn << PAGE_SHIFT) + offset);
70                         to = kptr + done;
71                 }
72                 memcpy(to, from, size);
73                 done += size;
74                 uaddr += size;
75         } while (done < n);
76         spin_unlock(&mm->page_table_lock);
77         return n - done;
78 fault:
79         spin_unlock(&mm->page_table_lock);
80         if (__handle_fault(uaddr, (unsigned long) pte, write_user))
81                 return n - done;
82         goto retry;
83 }
84
85 /*
86  * Do DAT for user address by page table walk, return kernel address.
87  * This function needs to be called with current->mm->page_table_lock held.
88  */
89 static __always_inline unsigned long __dat_user_addr(unsigned long uaddr)
90 {
91         struct mm_struct *mm = current->mm;
92         unsigned long pfn;
93         pte_t *pte;
94         int rc;
95
96 retry:
97         pte = follow_table(mm, uaddr);
98         if ((unsigned long) pte < 0x1000)
99                 goto fault;
100         if (!pte_present(*pte)) {
101                 pte = (pte_t *) 0x11;
102                 goto fault;
103         }
104
105         pfn = pte_pfn(*pte);
106         return (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
107 fault:
108         spin_unlock(&mm->page_table_lock);
109         rc = __handle_fault(uaddr, (unsigned long) pte, 0);
110         spin_lock(&mm->page_table_lock);
111         if (!rc)
112                 goto retry;
113         return 0;
114 }
115
116 size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
117 {
118         size_t rc;
119
120         if (segment_eq(get_fs(), KERNEL_DS)) {
121                 memcpy(to, (void __kernel __force *) from, n);
122                 return 0;
123         }
124         rc = __user_copy_pt((unsigned long) from, to, n, 0);
125         if (unlikely(rc))
126                 memset(to + n - rc, 0, rc);
127         return rc;
128 }
129
130 size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
131 {
132         if (segment_eq(get_fs(), KERNEL_DS)) {
133                 memcpy((void __kernel __force *) to, from, n);
134                 return 0;
135         }
136         return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
137 }
138
139 static size_t clear_user_pt(size_t n, void __user *to)
140 {
141         long done, size, ret;
142
143         if (segment_eq(get_fs(), KERNEL_DS)) {
144                 memset((void __kernel __force *) to, 0, n);
145                 return 0;
146         }
147         done = 0;
148         do {
149                 if (n - done > PAGE_SIZE)
150                         size = PAGE_SIZE;
151                 else
152                         size = n - done;
153                 ret = __user_copy_pt((unsigned long) to + done,
154                                       &empty_zero_page, size, 1);
155                 done += size;
156                 if (ret)
157                         return ret + n - done;
158         } while (done < n);
159         return 0;
160 }
161
162 static size_t strnlen_user_pt(size_t count, const char __user *src)
163 {
164         char *addr;
165         unsigned long uaddr = (unsigned long) src;
166         struct mm_struct *mm = current->mm;
167         unsigned long offset, pfn, done, len;
168         pte_t *pte;
169         size_t len_str;
170
171         if (segment_eq(get_fs(), KERNEL_DS))
172                 return strnlen((const char __kernel __force *) src, count) + 1;
173         done = 0;
174 retry:
175         spin_lock(&mm->page_table_lock);
176         do {
177                 pte = follow_table(mm, uaddr);
178                 if ((unsigned long) pte < 0x1000)
179                         goto fault;
180                 if (!pte_present(*pte)) {
181                         pte = (pte_t *) 0x11;
182                         goto fault;
183                 }
184
185                 pfn = pte_pfn(*pte);
186                 offset = uaddr & (PAGE_SIZE-1);
187                 addr = (char *)(pfn << PAGE_SHIFT) + offset;
188                 len = min(count - done, PAGE_SIZE - offset);
189                 len_str = strnlen(addr, len);
190                 done += len_str;
191                 uaddr += len_str;
192         } while ((len_str == len) && (done < count));
193         spin_unlock(&mm->page_table_lock);
194         return done + 1;
195 fault:
196         spin_unlock(&mm->page_table_lock);
197         if (__handle_fault(uaddr, (unsigned long) pte, 0))
198                 return 0;
199         goto retry;
200 }
201
202 static size_t strncpy_from_user_pt(size_t count, const char __user *src,
203                                    char *dst)
204 {
205         size_t n = strnlen_user_pt(count, src);
206
207         if (!n)
208                 return -EFAULT;
209         if (n > count)
210                 n = count;
211         if (segment_eq(get_fs(), KERNEL_DS)) {
212                 memcpy(dst, (const char __kernel __force *) src, n);
213                 if (dst[n-1] == '\0')
214                         return n-1;
215                 else
216                         return n;
217         }
218         if (__user_copy_pt((unsigned long) src, dst, n, 0))
219                 return -EFAULT;
220         if (dst[n-1] == '\0')
221                 return n-1;
222         else
223                 return n;
224 }
225
226 static size_t copy_in_user_pt(size_t n, void __user *to,
227                               const void __user *from)
228 {
229         struct mm_struct *mm = current->mm;
230         unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
231                       uaddr, done, size, error_code;
232         unsigned long uaddr_from = (unsigned long) from;
233         unsigned long uaddr_to = (unsigned long) to;
234         pte_t *pte_from, *pte_to;
235         int write_user;
236
237         if (segment_eq(get_fs(), KERNEL_DS)) {
238                 memcpy((void __force *) to, (void __force *) from, n);
239                 return 0;
240         }
241         done = 0;
242 retry:
243         spin_lock(&mm->page_table_lock);
244         do {
245                 write_user = 0;
246                 uaddr = uaddr_from;
247                 pte_from = follow_table(mm, uaddr_from);
248                 error_code = (unsigned long) pte_from;
249                 if (error_code < 0x1000)
250                         goto fault;
251                 if (!pte_present(*pte_from)) {
252                         error_code = 0x11;
253                         goto fault;
254                 }
255
256                 write_user = 1;
257                 uaddr = uaddr_to;
258                 pte_to = follow_table(mm, uaddr_to);
259                 error_code = (unsigned long) pte_to;
260                 if (error_code < 0x1000)
261                         goto fault;
262                 if (!pte_present(*pte_to)) {
263                         error_code = 0x11;
264                         goto fault;
265                 } else if (!pte_write(*pte_to)) {
266                         error_code = 0x04;
267                         goto fault;
268                 }
269
270                 pfn_from = pte_pfn(*pte_from);
271                 pfn_to = pte_pfn(*pte_to);
272                 offset_from = uaddr_from & (PAGE_SIZE-1);
273                 offset_to = uaddr_from & (PAGE_SIZE-1);
274                 offset_max = max(offset_from, offset_to);
275                 size = min(n - done, PAGE_SIZE - offset_max);
276
277                 memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
278                        (void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
279                 done += size;
280                 uaddr_from += size;
281                 uaddr_to += size;
282         } while (done < n);
283         spin_unlock(&mm->page_table_lock);
284         return n - done;
285 fault:
286         spin_unlock(&mm->page_table_lock);
287         if (__handle_fault(uaddr, error_code, write_user))
288                 return n - done;
289         goto retry;
290 }
291
292 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg)      \
293         asm volatile("0: l   %1,0(%6)\n"                                \
294                      "1: " insn                                         \
295                      "2: cs  %1,%2,0(%6)\n"                             \
296                      "3: jl  1b\n"                                      \
297                      "   lhi %0,0\n"                                    \
298                      "4:\n"                                             \
299                      EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b)    \
300                      : "=d" (ret), "=&d" (oldval), "=&d" (newval),      \
301                        "=m" (*uaddr)                                    \
302                      : "0" (-EFAULT), "d" (oparg), "a" (uaddr),         \
303                        "m" (*uaddr) : "cc" );
304
305 static int __futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
306 {
307         int oldval = 0, newval, ret;
308
309         switch (op) {
310         case FUTEX_OP_SET:
311                 __futex_atomic_op("lr %2,%5\n",
312                                   ret, oldval, newval, uaddr, oparg);
313                 break;
314         case FUTEX_OP_ADD:
315                 __futex_atomic_op("lr %2,%1\nar %2,%5\n",
316                                   ret, oldval, newval, uaddr, oparg);
317                 break;
318         case FUTEX_OP_OR:
319                 __futex_atomic_op("lr %2,%1\nor %2,%5\n",
320                                   ret, oldval, newval, uaddr, oparg);
321                 break;
322         case FUTEX_OP_ANDN:
323                 __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
324                                   ret, oldval, newval, uaddr, oparg);
325                 break;
326         case FUTEX_OP_XOR:
327                 __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
328                                   ret, oldval, newval, uaddr, oparg);
329                 break;
330         default:
331                 ret = -ENOSYS;
332         }
333         if (ret == 0)
334                 *old = oldval;
335         return ret;
336 }
337
338 int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
339 {
340         int ret;
341
342         if (segment_eq(get_fs(), KERNEL_DS))
343                 return __futex_atomic_op_pt(op, uaddr, oparg, old);
344         spin_lock(&current->mm->page_table_lock);
345         uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
346         if (!uaddr) {
347                 spin_unlock(&current->mm->page_table_lock);
348                 return -EFAULT;
349         }
350         get_page(virt_to_page(uaddr));
351         spin_unlock(&current->mm->page_table_lock);
352         ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
353         put_page(virt_to_page(uaddr));
354         return ret;
355 }
356
357 static int __futex_atomic_cmpxchg_pt(int *uval, int __user *uaddr,
358                                      int oldval, int newval)
359 {
360         int ret;
361
362         asm volatile("0: cs   %1,%4,0(%5)\n"
363                      "1: la   %0,0\n"
364                      "2:\n"
365                      EX_TABLE(0b,2b) EX_TABLE(1b,2b)
366                      : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
367                      : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
368                      : "cc", "memory" );
369         *uval = oldval;
370         return ret;
371 }
372
373 int futex_atomic_cmpxchg_pt(int *uval, int __user *uaddr,
374                             int oldval, int newval)
375 {
376         int ret;
377
378         if (segment_eq(get_fs(), KERNEL_DS))
379                 return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
380         spin_lock(&current->mm->page_table_lock);
381         uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
382         if (!uaddr) {
383                 spin_unlock(&current->mm->page_table_lock);
384                 return -EFAULT;
385         }
386         get_page(virt_to_page(uaddr));
387         spin_unlock(&current->mm->page_table_lock);
388         ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
389         put_page(virt_to_page(uaddr));
390         return ret;
391 }
392
393 struct uaccess_ops uaccess_pt = {
394         .copy_from_user         = copy_from_user_pt,
395         .copy_from_user_small   = copy_from_user_pt,
396         .copy_to_user           = copy_to_user_pt,
397         .copy_to_user_small     = copy_to_user_pt,
398         .copy_in_user           = copy_in_user_pt,
399         .clear_user             = clear_user_pt,
400         .strnlen_user           = strnlen_user_pt,
401         .strncpy_from_user      = strncpy_from_user_pt,
402         .futex_atomic_op        = futex_atomic_op_pt,
403         .futex_atomic_cmpxchg   = futex_atomic_cmpxchg_pt,
404 };