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

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  1 /*
  2  * OpenRISC Linux
  3  *
  4  * Linux architectural port borrowing liberally from similar works of
  5  * others.  All original copyrights apply as per the original source
  6  * declaration.
  7  *
  8  * OpenRISC implementation:
  9  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
 10  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
 11  * et al.
 12  *
 13  * This program is free software; you can redistribute it and/or modify
 14  * it under the terms of the GNU General Public License as published by
 15  * the Free Software Foundation; either version 2 of the License, or
 16  * (at your option) any later version.
 17  */
 18 
 19 #ifndef __ASM_OPENRISC_UACCESS_H
 20 #define __ASM_OPENRISC_UACCESS_H
 21 
 22 /*
 23  * User space memory access functions
 24  */
 25 #include <linux/errno.h>
 26 #include <linux/thread_info.h>
 27 #include <linux/prefetch.h>
 28 #include <linux/string.h>
 29 #include <asm/page.h>
 30 
 31 #define VERIFY_READ     0
 32 #define VERIFY_WRITE    1
 33 
 34 /*
 35  * The fs value determines whether argument validity checking should be
 36  * performed or not.  If get_fs() == USER_DS, checking is performed, with
 37  * get_fs() == KERNEL_DS, checking is bypassed.
 38  *
 39  * For historical reasons, these macros are grossly misnamed.
 40  */
 41 
 42 /* addr_limit is the maximum accessible address for the task. we misuse
 43  * the KERNEL_DS and USER_DS values to both assign and compare the
 44  * addr_limit values through the equally misnamed get/set_fs macros.
 45  * (see above)
 46  */
 47 
 48 #define KERNEL_DS       (~0UL)
 49 #define get_ds()        (KERNEL_DS)
 50 
 51 #define USER_DS         (TASK_SIZE)
 52 #define get_fs()        (current_thread_info()->addr_limit)
 53 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
 54 
 55 #define segment_eq(a, b)        ((a) == (b))
 56 
 57 /* Ensure that the range from addr to addr+size is all within the process'
 58  * address space
 59  */
 60 #define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs()-size))
 61 
 62 /* Ensure that addr is below task's addr_limit */
 63 #define __addr_ok(addr) ((unsigned long) addr < get_fs())
 64 
 65 #define access_ok(type, addr, size) \
 66         __range_ok((unsigned long)addr, (unsigned long)size)
 67 
 68 /*
 69  * The exception table consists of pairs of addresses: the first is the
 70  * address of an instruction that is allowed to fault, and the second is
 71  * the address at which the program should continue.  No registers are
 72  * modified, so it is entirely up to the continuation code to figure out
 73  * what to do.
 74  *
 75  * All the routines below use bits of fixup code that are out of line
 76  * with the main instruction path.  This means when everything is well,
 77  * we don't even have to jump over them.  Further, they do not intrude
 78  * on our cache or tlb entries.
 79  */
 80 
 81 struct exception_table_entry {
 82         unsigned long insn, fixup;
 83 };
 84 
 85 /* Returns 0 if exception not found and fixup otherwise.  */
 86 extern unsigned long search_exception_table(unsigned long);
 87 extern void sort_exception_table(void);
 88 
 89 /*
 90  * These are the main single-value transfer routines.  They automatically
 91  * use the right size if we just have the right pointer type.
 92  *
 93  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 94  * and yet we don't want to do any pointers, because that is too much
 95  * of a performance impact. Thus we have a few rather ugly macros here,
 96  * and hide all the uglyness from the user.
 97  *
 98  * The "__xxx" versions of the user access functions are versions that
 99  * do not verify the address space, that must have been done previously
100  * with a separate "access_ok()" call (this is used when we do multiple
101  * accesses to the same area of user memory).
102  *
103  * As we use the same address space for kernel and user data on the
104  * PowerPC, we can just do these as direct assignments.  (Of course, the
105  * exception handling means that it's no longer "just"...)
106  */
107 #define get_user(x, ptr) \
108         __get_user_check((x), (ptr), sizeof(*(ptr)))
109 #define put_user(x, ptr) \
110         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
111 
112 #define __get_user(x, ptr) \
113         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
114 #define __put_user(x, ptr) \
115         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
116 
117 extern long __put_user_bad(void);
118 
119 #define __put_user_nocheck(x, ptr, size)                \
120 ({                                                      \
121         long __pu_err;                                  \
122         __put_user_size((x), (ptr), (size), __pu_err);  \
123         __pu_err;                                       \
124 })
125 
126 #define __put_user_check(x, ptr, size)                                  \
127 ({                                                                      \
128         long __pu_err = -EFAULT;                                        \
129         __typeof__(*(ptr)) *__pu_addr = (ptr);                          \
130         if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
131                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
132         __pu_err;                                                       \
133 })
134 
135 #define __put_user_size(x, ptr, size, retval)                           \
136 do {                                                                    \
137         retval = 0;                                                     \
138         switch (size) {                                                 \
139         case 1: __put_user_asm(x, ptr, retval, "l.sb"); break;          \
140         case 2: __put_user_asm(x, ptr, retval, "l.sh"); break;          \
141         case 4: __put_user_asm(x, ptr, retval, "l.sw"); break;          \
142         case 8: __put_user_asm2(x, ptr, retval); break;                 \
143         default: __put_user_bad();                                      \
144         }                                                               \
145 } while (0)
146 
147 struct __large_struct {
148         unsigned long buf[100];
149 };
150 #define __m(x) (*(struct __large_struct *)(x))
151 
152 /*
153  * We don't tell gcc that we are accessing memory, but this is OK
154  * because we do not write to any memory gcc knows about, so there
155  * are no aliasing issues.
156  */
157 #define __put_user_asm(x, addr, err, op)                        \
158         __asm__ __volatile__(                                   \
159                 "1:     "op" 0(%2),%1\n"                        \
160                 "2:\n"                                          \
161                 ".section .fixup,\"ax\"\n"                      \
162                 "3:     l.addi %0,r0,%3\n"                      \
163                 "       l.j 2b\n"                               \
164                 "       l.nop\n"                                \
165                 ".previous\n"                                   \
166                 ".section __ex_table,\"a\"\n"                   \
167                 "       .align 2\n"                             \
168                 "       .long 1b,3b\n"                          \
169                 ".previous"                                     \
170                 : "=r"(err)                                     \
171                 : "r"(x), "r"(addr), "i"(-EFAULT), ""(err))
172 
173 #define __put_user_asm2(x, addr, err)                           \
174         __asm__ __volatile__(                                   \
175                 "1:     l.sw 0(%2),%1\n"                        \
176                 "2:     l.sw 4(%2),%H1\n"                       \
177                 "3:\n"                                          \
178                 ".section .fixup,\"ax\"\n"                      \
179                 "4:     l.addi %0,r0,%3\n"                      \
180                 "       l.j 3b\n"                               \
181                 "       l.nop\n"                                \
182                 ".previous\n"                                   \
183                 ".section __ex_table,\"a\"\n"                   \
184                 "       .align 2\n"                             \
185                 "       .long 1b,4b\n"                          \
186                 "       .long 2b,4b\n"                          \
187                 ".previous"                                     \
188                 : "=r"(err)                                     \
189                 : "r"(x), "r"(addr), "i"(-EFAULT), ""(err))
190 
191 #define __get_user_nocheck(x, ptr, size)                        \
192 ({                                                              \
193         long __gu_err, __gu_val;                                \
194         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
195         (x) = (__force __typeof__(*(ptr)))__gu_val;             \
196         __gu_err;                                               \
197 })
198 
199 #define __get_user_check(x, ptr, size)                                  \
200 ({                                                                      \
201         long __gu_err = -EFAULT, __gu_val = 0;                          \
202         const __typeof__(*(ptr)) * __gu_addr = (ptr);                   \
203         if (access_ok(VERIFY_READ, __gu_addr, size))                    \
204                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
205         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
206         __gu_err;                                                       \
207 })
208 
209 extern long __get_user_bad(void);
210 
211 #define __get_user_size(x, ptr, size, retval)                           \
212 do {                                                                    \
213         retval = 0;                                                     \
214         switch (size) {                                                 \
215         case 1: __get_user_asm(x, ptr, retval, "l.lbz"); break;         \
216         case 2: __get_user_asm(x, ptr, retval, "l.lhz"); break;         \
217         case 4: __get_user_asm(x, ptr, retval, "l.lwz"); break;         \
218         case 8: __get_user_asm2(x, ptr, retval);                        \
219         default: (x) = __get_user_bad();                                \
220         }                                                               \
221 } while (0)
222 
223 #define __get_user_asm(x, addr, err, op)                \
224         __asm__ __volatile__(                           \
225                 "1:     "op" %1,0(%2)\n"                \
226                 "2:\n"                                  \
227                 ".section .fixup,\"ax\"\n"              \
228                 "3:     l.addi %0,r0,%3\n"              \
229                 "       l.addi %1,r0,0\n"               \
230                 "       l.j 2b\n"                       \
231                 "       l.nop\n"                        \
232                 ".previous\n"                           \
233                 ".section __ex_table,\"a\"\n"           \
234                 "       .align 2\n"                     \
235                 "       .long 1b,3b\n"                  \
236                 ".previous"                             \
237                 : "=r"(err), "=r"(x)                    \
238                 : "r"(addr), "i"(-EFAULT), ""(err))
239 
240 #define __get_user_asm2(x, addr, err)                   \
241         __asm__ __volatile__(                           \
242                 "1:     l.lwz %1,0(%2)\n"               \
243                 "2:     l.lwz %H1,4(%2)\n"              \
244                 "3:\n"                                  \
245                 ".section .fixup,\"ax\"\n"              \
246                 "4:     l.addi %0,r0,%3\n"              \
247                 "       l.addi %1,r0,0\n"               \
248                 "       l.addi %H1,r0,0\n"              \
249                 "       l.j 3b\n"                       \
250                 "       l.nop\n"                        \
251                 ".previous\n"                           \
252                 ".section __ex_table,\"a\"\n"           \
253                 "       .align 2\n"                     \
254                 "       .long 1b,4b\n"                  \
255                 "       .long 2b,4b\n"                  \
256                 ".previous"                             \
257                 : "=r"(err), "=&r"(x)                   \
258                 : "r"(addr), "i"(-EFAULT), ""(err))
259 
260 /* more complex routines */
261 
262 extern unsigned long __must_check
263 __copy_tofrom_user(void *to, const void *from, unsigned long size);
264 
265 #define __copy_from_user(to, from, size) \
266         __copy_tofrom_user(to, from, size)
267 #define __copy_to_user(to, from, size) \
268         __copy_tofrom_user(to, from, size)
269 
270 #define __copy_to_user_inatomic __copy_to_user
271 #define __copy_from_user_inatomic __copy_from_user
272 
273 static inline unsigned long
274 copy_from_user(void *to, const void *from, unsigned long n)
275 {
276         unsigned long res = n;
277 
278         if (likely(access_ok(VERIFY_READ, from, n)))
279                 res = __copy_tofrom_user(to, from, n);
280         if (unlikely(res))
281                 memset(to + (n - res), 0, res);
282         return res;
283 }
284 
285 static inline unsigned long
286 copy_to_user(void *to, const void *from, unsigned long n)
287 {
288         if (likely(access_ok(VERIFY_WRITE, to, n)))
289                 n = __copy_tofrom_user(to, from, n);
290         return n;
291 }
292 
293 extern unsigned long __clear_user(void *addr, unsigned long size);
294 
295 static inline __must_check unsigned long
296 clear_user(void *addr, unsigned long size)
297 {
298         if (likely(access_ok(VERIFY_WRITE, addr, size)))
299                 size = __clear_user(addr, size);
300         return size;
301 }
302 
303 #define user_addr_max() \
304         (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
305 
306 extern long strncpy_from_user(char *dest, const char __user *src, long count);
307 
308 extern __must_check long strlen_user(const char __user *str);
309 extern __must_check long strnlen_user(const char __user *str, long n);
310 
311 #endif /* __ASM_OPENRISC_UACCESS_H */
312 

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