Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6.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 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 ? FAULT_FLAG_WRITE : 0);
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
123                 offset = uaddr & (PAGE_SIZE - 1);
124                 size = min(n - done, PAGE_SIZE - offset);
125                 if (write_user) {
126                         to = (void *)((pfn << PAGE_SHIFT) + offset);
127                         from = kptr + done;
128                 } else {
129                         from = (void *)((pfn << PAGE_SHIFT) + offset);
130                         to = kptr + done;
131                 }
132                 memcpy(to, from, size);
133                 done += size;
134                 uaddr += size;
135         } while (done < n);
136         spin_unlock(&mm->page_table_lock);
137         return n - done;
138 fault:
139         spin_unlock(&mm->page_table_lock);
140         if (__handle_fault(mm, uaddr, write_user))
141                 return n - done;
142         goto retry;
143 }
144
145 /*
146  * Do DAT for user address by page table walk, return kernel address.
147  * This function needs to be called with current->mm->page_table_lock held.
148  */
149 static unsigned long __dat_user_addr(unsigned long uaddr)
150 {
151         struct mm_struct *mm = current->mm;
152         unsigned long pfn, ret;
153         pte_t *pte;
154         int rc;
155
156         ret = 0;
157 retry:
158         pte = follow_table(mm, uaddr);
159         if (!pte || !pte_present(*pte))
160                 goto fault;
161
162         pfn = pte_pfn(*pte);
163         ret = (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
164 out:
165         return ret;
166 fault:
167         spin_unlock(&mm->page_table_lock);
168         rc = __handle_fault(mm, uaddr, 0);
169         spin_lock(&mm->page_table_lock);
170         if (rc)
171                 goto out;
172         goto retry;
173 }
174
175 size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
176 {
177         size_t rc;
178
179         if (segment_eq(get_fs(), KERNEL_DS)) {
180                 memcpy(to, (void __kernel __force *) from, n);
181                 return 0;
182         }
183         rc = __user_copy_pt((unsigned long) from, to, n, 0);
184         if (unlikely(rc))
185                 memset(to + n - rc, 0, rc);
186         return rc;
187 }
188
189 size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
190 {
191         if (segment_eq(get_fs(), KERNEL_DS)) {
192                 memcpy((void __kernel __force *) to, from, n);
193                 return 0;
194         }
195         return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
196 }
197
198 static size_t clear_user_pt(size_t n, void __user *to)
199 {
200         long done, size, ret;
201
202         if (segment_eq(get_fs(), KERNEL_DS)) {
203                 memset((void __kernel __force *) to, 0, n);
204                 return 0;
205         }
206         done = 0;
207         do {
208                 if (n - done > PAGE_SIZE)
209                         size = PAGE_SIZE;
210                 else
211                         size = n - done;
212                 ret = __user_copy_pt((unsigned long) to + done,
213                                       &empty_zero_page, size, 1);
214                 done += size;
215                 if (ret)
216                         return ret + n - done;
217         } while (done < n);
218         return 0;
219 }
220
221 static size_t strnlen_user_pt(size_t count, const char __user *src)
222 {
223         char *addr;
224         unsigned long uaddr = (unsigned long) src;
225         struct mm_struct *mm = current->mm;
226         unsigned long offset, pfn, done, len;
227         pte_t *pte;
228         size_t len_str;
229
230         if (segment_eq(get_fs(), KERNEL_DS))
231                 return strnlen((const char __kernel __force *) src, count) + 1;
232         done = 0;
233 retry:
234         spin_lock(&mm->page_table_lock);
235         do {
236                 pte = follow_table(mm, uaddr);
237                 if (!pte || !pte_present(*pte))
238                         goto fault;
239
240                 pfn = pte_pfn(*pte);
241                 offset = uaddr & (PAGE_SIZE-1);
242                 addr = (char *)(pfn << PAGE_SHIFT) + offset;
243                 len = min(count - done, PAGE_SIZE - offset);
244                 len_str = strnlen(addr, len);
245                 done += len_str;
246                 uaddr += len_str;
247         } while ((len_str == len) && (done < count));
248         spin_unlock(&mm->page_table_lock);
249         return done + 1;
250 fault:
251         spin_unlock(&mm->page_table_lock);
252         if (__handle_fault(mm, uaddr, 0)) {
253                 return 0;
254         }
255         goto retry;
256 }
257
258 static size_t strncpy_from_user_pt(size_t count, const char __user *src,
259                                    char *dst)
260 {
261         size_t n = strnlen_user_pt(count, src);
262
263         if (!n)
264                 return -EFAULT;
265         if (n > count)
266                 n = count;
267         if (segment_eq(get_fs(), KERNEL_DS)) {
268                 memcpy(dst, (const char __kernel __force *) src, n);
269                 if (dst[n-1] == '\0')
270                         return n-1;
271                 else
272                         return n;
273         }
274         if (__user_copy_pt((unsigned long) src, dst, n, 0))
275                 return -EFAULT;
276         if (dst[n-1] == '\0')
277                 return n-1;
278         else
279                 return n;
280 }
281
282 static size_t copy_in_user_pt(size_t n, void __user *to,
283                               const void __user *from)
284 {
285         struct mm_struct *mm = current->mm;
286         unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
287                       uaddr, done, size;
288         unsigned long uaddr_from = (unsigned long) from;
289         unsigned long uaddr_to = (unsigned long) to;
290         pte_t *pte_from, *pte_to;
291         int write_user;
292
293         if (segment_eq(get_fs(), KERNEL_DS)) {
294                 memcpy((void __force *) to, (void __force *) from, n);
295                 return 0;
296         }
297         done = 0;
298 retry:
299         spin_lock(&mm->page_table_lock);
300         do {
301                 pte_from = follow_table(mm, uaddr_from);
302                 if (!pte_from || !pte_present(*pte_from)) {
303                         uaddr = uaddr_from;
304                         write_user = 0;
305                         goto fault;
306                 }
307
308                 pte_to = follow_table(mm, uaddr_to);
309                 if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) {
310                         uaddr = uaddr_to;
311                         write_user = 1;
312                         goto fault;
313                 }
314
315                 pfn_from = pte_pfn(*pte_from);
316                 pfn_to = pte_pfn(*pte_to);
317                 offset_from = uaddr_from & (PAGE_SIZE-1);
318                 offset_to = uaddr_from & (PAGE_SIZE-1);
319                 offset_max = max(offset_from, offset_to);
320                 size = min(n - done, PAGE_SIZE - offset_max);
321
322                 memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
323                        (void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
324                 done += size;
325                 uaddr_from += size;
326                 uaddr_to += size;
327         } while (done < n);
328         spin_unlock(&mm->page_table_lock);
329         return n - done;
330 fault:
331         spin_unlock(&mm->page_table_lock);
332         if (__handle_fault(mm, uaddr, write_user))
333                 return n - done;
334         goto retry;
335 }
336
337 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg)      \
338         asm volatile("0: l   %1,0(%6)\n"                                \
339                      "1: " insn                                         \
340                      "2: cs  %1,%2,0(%6)\n"                             \
341                      "3: jl  1b\n"                                      \
342                      "   lhi %0,0\n"                                    \
343                      "4:\n"                                             \
344                      EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b)    \
345                      : "=d" (ret), "=&d" (oldval), "=&d" (newval),      \
346                        "=m" (*uaddr)                                    \
347                      : "0" (-EFAULT), "d" (oparg), "a" (uaddr),         \
348                        "m" (*uaddr) : "cc" );
349
350 static int __futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
351 {
352         int oldval = 0, newval, ret;
353
354         switch (op) {
355         case FUTEX_OP_SET:
356                 __futex_atomic_op("lr %2,%5\n",
357                                   ret, oldval, newval, uaddr, oparg);
358                 break;
359         case FUTEX_OP_ADD:
360                 __futex_atomic_op("lr %2,%1\nar %2,%5\n",
361                                   ret, oldval, newval, uaddr, oparg);
362                 break;
363         case FUTEX_OP_OR:
364                 __futex_atomic_op("lr %2,%1\nor %2,%5\n",
365                                   ret, oldval, newval, uaddr, oparg);
366                 break;
367         case FUTEX_OP_ANDN:
368                 __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
369                                   ret, oldval, newval, uaddr, oparg);
370                 break;
371         case FUTEX_OP_XOR:
372                 __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
373                                   ret, oldval, newval, uaddr, oparg);
374                 break;
375         default:
376                 ret = -ENOSYS;
377         }
378         if (ret == 0)
379                 *old = oldval;
380         return ret;
381 }
382
383 int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
384 {
385         int ret;
386
387         if (segment_eq(get_fs(), KERNEL_DS))
388                 return __futex_atomic_op_pt(op, uaddr, oparg, old);
389         spin_lock(&current->mm->page_table_lock);
390         uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
391         if (!uaddr) {
392                 spin_unlock(&current->mm->page_table_lock);
393                 return -EFAULT;
394         }
395         get_page(virt_to_page(uaddr));
396         spin_unlock(&current->mm->page_table_lock);
397         ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
398         put_page(virt_to_page(uaddr));
399         return ret;
400 }
401
402 static int __futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
403 {
404         int ret;
405
406         asm volatile("0: cs   %1,%4,0(%5)\n"
407                      "1: lr   %0,%1\n"
408                      "2:\n"
409                      EX_TABLE(0b,2b) EX_TABLE(1b,2b)
410                      : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
411                      : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
412                      : "cc", "memory" );
413         return ret;
414 }
415
416 int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
417 {
418         int ret;
419
420         if (segment_eq(get_fs(), KERNEL_DS))
421                 return __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
422         spin_lock(&current->mm->page_table_lock);
423         uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
424         if (!uaddr) {
425                 spin_unlock(&current->mm->page_table_lock);
426                 return -EFAULT;
427         }
428         get_page(virt_to_page(uaddr));
429         spin_unlock(&current->mm->page_table_lock);
430         ret = __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
431         put_page(virt_to_page(uaddr));
432         return ret;
433 }
434
435 struct uaccess_ops uaccess_pt = {
436         .copy_from_user         = copy_from_user_pt,
437         .copy_from_user_small   = copy_from_user_pt,
438         .copy_to_user           = copy_to_user_pt,
439         .copy_to_user_small     = copy_to_user_pt,
440         .copy_in_user           = copy_in_user_pt,
441         .clear_user             = clear_user_pt,
442         .strnlen_user           = strnlen_user_pt,
443         .strncpy_from_user      = strncpy_from_user_pt,
444         .futex_atomic_op        = futex_atomic_op_pt,
445         .futex_atomic_cmpxchg   = futex_atomic_cmpxchg_pt,
446 };