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), "0"(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), "0"(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) = (__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) = (__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), "0"(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), "0"(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 over;
277 
278 	if (access_ok(VERIFY_READ, from, n))
279 		return __copy_tofrom_user(to, from, n);
280 	if ((unsigned long)from < TASK_SIZE) {
281 		over = (unsigned long)from + n - TASK_SIZE;
282 		return __copy_tofrom_user(to, from, n - over) + over;
283 	}
284 	return n;
285 }
286 
287 static inline unsigned long
288 copy_to_user(void *to, const void *from, unsigned long n)
289 {
290 	unsigned long over;
291 
292 	if (access_ok(VERIFY_WRITE, to, n))
293 		return __copy_tofrom_user(to, from, n);
294 	if ((unsigned long)to < TASK_SIZE) {
295 		over = (unsigned long)to + n - TASK_SIZE;
296 		return __copy_tofrom_user(to, from, n - over) + over;
297 	}
298 	return n;
299 }
300 
301 extern unsigned long __clear_user(void *addr, unsigned long size);
302 
303 static inline __must_check unsigned long
304 clear_user(void *addr, unsigned long size)
305 {
306 
307 	if (access_ok(VERIFY_WRITE, addr, size))
308 		return __clear_user(addr, size);
309 	if ((unsigned long)addr < TASK_SIZE) {
310 		unsigned long over = (unsigned long)addr + size - TASK_SIZE;
311 		return __clear_user(addr, size - over) + over;
312 	}
313 	return size;
314 }
315 
316 #define user_addr_max() \
317 	(segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
318 
319 extern long strncpy_from_user(char *dest, const char __user *src, long count);
320 
321 extern __must_check long strlen_user(const char __user *str);
322 extern __must_check long strnlen_user(const char __user *str, long n);
323 
324 #endif /* __ASM_OPENRISC_UACCESS_H */
325