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Linux/arch/arm64/include/asm/uaccess.h

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  1 /*
  2  * Based on arch/arm/include/asm/uaccess.h
  3  *
  4  * Copyright (C) 2012 ARM Ltd.
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License version 2 as
  8  * published by the Free Software Foundation.
  9  *
 10  * This program is distributed in the hope that it will be useful,
 11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13  * GNU General Public License for more details.
 14  *
 15  * You should have received a copy of the GNU General Public License
 16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 17  */
 18 #ifndef __ASM_UACCESS_H
 19 #define __ASM_UACCESS_H
 20 
 21 /*
 22  * User space memory access functions
 23  */
 24 #include <linux/string.h>
 25 #include <linux/thread_info.h>
 26 
 27 #include <asm/ptrace.h>
 28 #include <asm/errno.h>
 29 #include <asm/memory.h>
 30 #include <asm/compiler.h>
 31 
 32 #define VERIFY_READ 0
 33 #define VERIFY_WRITE 1
 34 
 35 /*
 36  * The exception table consists of pairs of addresses: the first is the
 37  * address of an instruction that is allowed to fault, and the second is
 38  * the address at which the program should continue.  No registers are
 39  * modified, so it is entirely up to the continuation code to figure out
 40  * what to do.
 41  *
 42  * All the routines below use bits of fixup code that are out of line
 43  * with the main instruction path.  This means when everything is well,
 44  * we don't even have to jump over them.  Further, they do not intrude
 45  * on our cache or tlb entries.
 46  */
 47 
 48 struct exception_table_entry
 49 {
 50         unsigned long insn, fixup;
 51 };
 52 
 53 extern int fixup_exception(struct pt_regs *regs);
 54 
 55 #define KERNEL_DS       (-1UL)
 56 #define get_ds()        (KERNEL_DS)
 57 
 58 #define USER_DS         TASK_SIZE_64
 59 #define get_fs()        (current_thread_info()->addr_limit)
 60 
 61 static inline void set_fs(mm_segment_t fs)
 62 {
 63         current_thread_info()->addr_limit = fs;
 64 }
 65 
 66 #define segment_eq(a,b) ((a) == (b))
 67 
 68 /*
 69  * Return 1 if addr < current->addr_limit, 0 otherwise.
 70  */
 71 #define __addr_ok(addr)                                                 \
 72 ({                                                                      \
 73         unsigned long flag;                                             \
 74         asm("cmp %1, %0; cset %0, lo"                                   \
 75                 : "=&r" (flag)                                          \
 76                 : "r" (addr), "" (current_thread_info()->addr_limit)   \
 77                 : "cc");                                                \
 78         flag;                                                           \
 79 })
 80 
 81 /*
 82  * Test whether a block of memory is a valid user space address.
 83  * Returns 1 if the range is valid, 0 otherwise.
 84  *
 85  * This is equivalent to the following test:
 86  * (u65)addr + (u65)size < (u65)current->addr_limit
 87  *
 88  * This needs 65-bit arithmetic.
 89  */
 90 #define __range_ok(addr, size)                                          \
 91 ({                                                                      \
 92         unsigned long flag, roksum;                                     \
 93         __chk_user_ptr(addr);                                           \
 94         asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, cc"         \
 95                 : "=&r" (flag), "=&r" (roksum)                          \
 96                 : "1" (addr), "Ir" (size),                              \
 97                   "r" (current_thread_info()->addr_limit)               \
 98                 : "cc");                                                \
 99         flag;                                                           \
100 })
101 
102 #define access_ok(type, addr, size)     __range_ok(addr, size)
103 
104 /*
105  * The "__xxx" versions of the user access functions do not verify the address
106  * space - it must have been done previously with a separate "access_ok()"
107  * call.
108  *
109  * The "__xxx_error" versions set the third argument to -EFAULT if an error
110  * occurs, and leave it unchanged on success.
111  */
112 #define __get_user_asm(instr, reg, x, addr, err)                        \
113         asm volatile(                                                   \
114         "1:     " instr "       " reg "1, [%2]\n"                       \
115         "2:\n"                                                          \
116         "       .section .fixup, \"ax\"\n"                              \
117         "       .align  2\n"                                            \
118         "3:     mov     %w0, %3\n"                                      \
119         "       mov     %1, #0\n"                                       \
120         "       b       2b\n"                                           \
121         "       .previous\n"                                            \
122         "       .section __ex_table,\"a\"\n"                            \
123         "       .align  3\n"                                            \
124         "       .quad   1b, 3b\n"                                       \
125         "       .previous"                                              \
126         : "+r" (err), "=&r" (x)                                         \
127         : "r" (addr), "i" (-EFAULT))
128 
129 #define __get_user_err(x, ptr, err)                                     \
130 do {                                                                    \
131         unsigned long __gu_val;                                         \
132         __chk_user_ptr(ptr);                                            \
133         switch (sizeof(*(ptr))) {                                       \
134         case 1:                                                         \
135                 __get_user_asm("ldrb", "%w", __gu_val, (ptr), (err));   \
136                 break;                                                  \
137         case 2:                                                         \
138                 __get_user_asm("ldrh", "%w", __gu_val, (ptr), (err));   \
139                 break;                                                  \
140         case 4:                                                         \
141                 __get_user_asm("ldr", "%w", __gu_val, (ptr), (err));    \
142                 break;                                                  \
143         case 8:                                                         \
144                 __get_user_asm("ldr", "%",  __gu_val, (ptr), (err));    \
145                 break;                                                  \
146         default:                                                        \
147                 BUILD_BUG();                                            \
148         }                                                               \
149         (x) = (__typeof__(*(ptr)))__gu_val;                             \
150 } while (0)
151 
152 #define __get_user(x, ptr)                                              \
153 ({                                                                      \
154         int __gu_err = 0;                                               \
155         __get_user_err((x), (ptr), __gu_err);                           \
156         __gu_err;                                                       \
157 })
158 
159 #define __get_user_error(x, ptr, err)                                   \
160 ({                                                                      \
161         __get_user_err((x), (ptr), (err));                              \
162         (void)0;                                                        \
163 })
164 
165 #define __get_user_unaligned __get_user
166 
167 #define get_user(x, ptr)                                                \
168 ({                                                                      \
169         __typeof__(*(ptr)) __user *__p = (ptr);                         \
170         might_fault();                                                  \
171         access_ok(VERIFY_READ, __p, sizeof(*__p)) ?                     \
172                 __get_user((x), __p) :                                  \
173                 ((x) = 0, -EFAULT);                                     \
174 })
175 
176 #define __put_user_asm(instr, reg, x, addr, err)                        \
177         asm volatile(                                                   \
178         "1:     " instr "       " reg "1, [%2]\n"                       \
179         "2:\n"                                                          \
180         "       .section .fixup,\"ax\"\n"                               \
181         "       .align  2\n"                                            \
182         "3:     mov     %w0, %3\n"                                      \
183         "       b       2b\n"                                           \
184         "       .previous\n"                                            \
185         "       .section __ex_table,\"a\"\n"                            \
186         "       .align  3\n"                                            \
187         "       .quad   1b, 3b\n"                                       \
188         "       .previous"                                              \
189         : "+r" (err)                                                    \
190         : "r" (x), "r" (addr), "i" (-EFAULT))
191 
192 #define __put_user_err(x, ptr, err)                                     \
193 do {                                                                    \
194         __typeof__(*(ptr)) __pu_val = (x);                              \
195         __chk_user_ptr(ptr);                                            \
196         switch (sizeof(*(ptr))) {                                       \
197         case 1:                                                         \
198                 __put_user_asm("strb", "%w", __pu_val, (ptr), (err));   \
199                 break;                                                  \
200         case 2:                                                         \
201                 __put_user_asm("strh", "%w", __pu_val, (ptr), (err));   \
202                 break;                                                  \
203         case 4:                                                         \
204                 __put_user_asm("str",  "%w", __pu_val, (ptr), (err));   \
205                 break;                                                  \
206         case 8:                                                         \
207                 __put_user_asm("str",  "%", __pu_val, (ptr), (err));    \
208                 break;                                                  \
209         default:                                                        \
210                 BUILD_BUG();                                            \
211         }                                                               \
212 } while (0)
213 
214 #define __put_user(x, ptr)                                              \
215 ({                                                                      \
216         int __pu_err = 0;                                               \
217         __put_user_err((x), (ptr), __pu_err);                           \
218         __pu_err;                                                       \
219 })
220 
221 #define __put_user_error(x, ptr, err)                                   \
222 ({                                                                      \
223         __put_user_err((x), (ptr), (err));                              \
224         (void)0;                                                        \
225 })
226 
227 #define __put_user_unaligned __put_user
228 
229 #define put_user(x, ptr)                                                \
230 ({                                                                      \
231         __typeof__(*(ptr)) __user *__p = (ptr);                         \
232         might_fault();                                                  \
233         access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ?                    \
234                 __put_user((x), __p) :                                  \
235                 -EFAULT;                                                \
236 })
237 
238 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
239 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
240 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
241 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
242 
243 extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
244 extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
245 
246 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
247 {
248         if (access_ok(VERIFY_READ, from, n))
249                 n = __copy_from_user(to, from, n);
250         else /* security hole - plug it */
251                 memset(to, 0, n);
252         return n;
253 }
254 
255 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
256 {
257         if (access_ok(VERIFY_WRITE, to, n))
258                 n = __copy_to_user(to, from, n);
259         return n;
260 }
261 
262 static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n)
263 {
264         if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n))
265                 n = __copy_in_user(to, from, n);
266         return n;
267 }
268 
269 #define __copy_to_user_inatomic __copy_to_user
270 #define __copy_from_user_inatomic __copy_from_user
271 
272 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
273 {
274         if (access_ok(VERIFY_WRITE, to, n))
275                 n = __clear_user(to, n);
276         return n;
277 }
278 
279 static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
280 {
281         long res = -EFAULT;
282         if (access_ok(VERIFY_READ, src, 1))
283                 res = __strncpy_from_user(dst, src, count);
284         return res;
285 }
286 
287 #define strlen_user(s)  strnlen_user(s, ~0UL >> 1)
288 
289 static inline long __must_check strnlen_user(const char __user *s, long n)
290 {
291         unsigned long res = 0;
292 
293         if (__addr_ok(s))
294                 res = __strnlen_user(s, n);
295 
296         return res;
297 }
298 
299 #endif /* __ASM_UACCESS_H */
300 

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