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Committer: Michael Beasley <mike@snafu.setup>
[mikesnafu-overlay.git] / arch / s390 / lib / uaccess_pt.c
blob5efdfe9f5e769732a17ca2b60bcee062f408e38b
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 done = 0;
306 retry:
307 spin_lock(&mm->page_table_lock);
308 do {
309 pte_from = follow_table(mm, uaddr_from);
310 if (!pte_from || !pte_present(*pte_from)) {
311 uaddr = uaddr_from;
312 write_user = 0;
313 goto fault;
314 }
315
316 pte_to = follow_table(mm, uaddr_to);
317 if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) {
318 uaddr = uaddr_to;
319 write_user = 1;
320 goto fault;
321 }
322
323 pfn_from = pte_pfn(*pte_from);
324 if (!pfn_valid(pfn_from))
325 goto out;
326 pfn_to = pte_pfn(*pte_to);
327 if (!pfn_valid(pfn_to))
328 goto out;
329
330 offset_from = uaddr_from & (PAGE_SIZE-1);
331 offset_to = uaddr_from & (PAGE_SIZE-1);
332 offset_max = max(offset_from, offset_to);
333 size = min(n - done, PAGE_SIZE - offset_max);
334
335 memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
336 (void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
337 done += size;
338 uaddr_from += size;
339 uaddr_to += size;
340 } while (done < n);
341 out:
342 spin_unlock(&mm->page_table_lock);
343 return n - done;
344 fault:
345 spin_unlock(&mm->page_table_lock);
346 if (__handle_fault(mm, uaddr, write_user))
347 return n - done;
348 goto retry;
349 }
350
351 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
352 asm volatile("0: l %1,0(%6)\n" \
353 "1: " insn \
354 "2: cs %1,%2,0(%6)\n" \
355 "3: jl 1b\n" \
356 " lhi %0,0\n" \
357 "4:\n" \
358 EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
359 : "=d" (ret), "=&d" (oldval), "=&d" (newval), \
360 "=m" (*uaddr) \
361 : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
362 "m" (*uaddr) : "cc" );
363
364 int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
365 {
366 int oldval = 0, newval, ret;
367
368 spin_lock(&current->mm->page_table_lock);
369 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
370 if (!uaddr) {
371 spin_unlock(&current->mm->page_table_lock);
372 return -EFAULT;
373 }
374 get_page(virt_to_page(uaddr));
375 spin_unlock(&current->mm->page_table_lock);
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 put_page(virt_to_page(uaddr));
401 *old = oldval;
402 return ret;
403 }
404
405 int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
406 {
407 int ret;
408
409 if (!current->mm)
410 return -EFAULT;
411 spin_lock(&current->mm->page_table_lock);
412 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
413 if (!uaddr) {
414 spin_unlock(&current->mm->page_table_lock);
415 return -EFAULT;
416 }
417 get_page(virt_to_page(uaddr));
418 spin_unlock(&current->mm->page_table_lock);
419 asm volatile(" cs %1,%4,0(%5)\n"
420 "0: lr %0,%1\n"
421 "1:\n"
422 EX_TABLE(0b,1b)
423 : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
424 : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
425 : "cc", "memory" );
426 put_page(virt_to_page(uaddr));
427 return ret;
428 }
429
430 struct uaccess_ops uaccess_pt = {
431 .copy_from_user = copy_from_user_pt,
432 .copy_from_user_small = copy_from_user_pt,
433 .copy_to_user = copy_to_user_pt,
434 .copy_to_user_small = copy_to_user_pt,
435 .copy_in_user = copy_in_user_pt,
436 .clear_user = clear_user_pt,
437 .strnlen_user = strnlen_user_pt,
438 .strncpy_from_user = strncpy_from_user_pt,
439 .futex_atomic_op = futex_atomic_op_pt,
440 .futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
441 };
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