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
follow_table(struct mm_struct * mm,unsigned long addr)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
__user_copy_pt(unsigned long uaddr,void * kptr,size_t n,int write_user)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 */
__dat_user_addr(unsigned long uaddr)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
copy_from_user_pt(size_t n,const void __user * from,void * to)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
copy_to_user_pt(size_t n,void __user * to,const void * from)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
clear_user_pt(size_t n,void __user * to)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
strnlen_user_pt(size_t count,const char __user * src)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
strncpy_from_user_pt(size_t count,const char __user * src,char * dst)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
copy_in_user_pt(size_t n,void __user * to,const void __user * from)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
__futex_atomic_op_pt(int op,u32 __user * uaddr,int oparg,int * old)305 static int __futex_atomic_op_pt(int op, u32 __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
futex_atomic_op_pt(int op,u32 __user * uaddr,int oparg,int * old)338 int futex_atomic_op_pt(int op, u32 __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(¤t->mm->page_table_lock);
345 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
346 if (!uaddr) {
347 spin_unlock(¤t->mm->page_table_lock);
348 return -EFAULT;
349 }
350 get_page(virt_to_page(uaddr));
351 spin_unlock(¤t->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
__futex_atomic_cmpxchg_pt(u32 * uval,u32 __user * uaddr,u32 oldval,u32 newval)357 static int __futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
358 u32 oldval, u32 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
futex_atomic_cmpxchg_pt(u32 * uval,u32 __user * uaddr,u32 oldval,u32 newval)373 int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
374 u32 oldval, u32 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(¤t->mm->page_table_lock);
381 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
382 if (!uaddr) {
383 spin_unlock(¤t->mm->page_table_lock);
384 return -EFAULT;
385 }
386 get_page(virt_to_page(uaddr));
387 spin_unlock(¤t->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 };
405