1 /*
2  * uaccess.h: User space memore access functions.
3  *
4  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
5  * Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
6  */
7 #ifndef _ASM_UACCESS_H
8 #define _ASM_UACCESS_H
9 
10 #ifdef __KERNEL__
11 #include <linux/compiler.h>
12 #include <linux/sched.h>
13 #include <linux/string.h>
14 #include <linux/errno.h>
15 #endif
16 
17 #ifndef __ASSEMBLY__
18 
19 #include <asm/processor.h>
20 
21 #define ARCH_HAS_SORT_EXTABLE
22 #define ARCH_HAS_SEARCH_EXTABLE
23 
24 /* Sparc is not segmented, however we need to be able to fool access_ok()
25  * when doing system calls from kernel mode legitimately.
26  *
27  * "For historical reasons, these macros are grossly misnamed." -Linus
28  */
29 
30 #define KERNEL_DS   ((mm_segment_t) { 0 })
31 #define USER_DS     ((mm_segment_t) { -1 })
32 
33 #define VERIFY_READ	0
34 #define VERIFY_WRITE	1
35 
36 #define get_ds()	(KERNEL_DS)
37 #define get_fs()	(current->thread.current_ds)
38 #define set_fs(val)	((current->thread.current_ds) = (val))
39 
40 #define segment_eq(a, b) ((a).seg == (b).seg)
41 
42 /* We have there a nice not-mapped page at PAGE_OFFSET - PAGE_SIZE, so that this test
43  * can be fairly lightweight.
44  * No one can read/write anything from userland in the kernel space by setting
45  * large size and address near to PAGE_OFFSET - a fault will break his intentions.
46  */
47 #define __user_ok(addr, size) ({ (void)(size); (addr) < STACK_TOP; })
48 #define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
49 #define __access_ok(addr, size) (__user_ok((addr) & get_fs().seg, (size)))
50 #define access_ok(type, addr, size) \
51 	({ (void)(type); __access_ok((unsigned long)(addr), size); })
52 
53 /*
54  * The exception table consists of pairs of addresses: the first is the
55  * address of an instruction that is allowed to fault, and the second is
56  * the address at which the program should continue.  No registers are
57  * modified, so it is entirely up to the continuation code to figure out
58  * what to do.
59  *
60  * All the routines below use bits of fixup code that are out of line
61  * with the main instruction path.  This means when everything is well,
62  * we don't even have to jump over them.  Further, they do not intrude
63  * on our cache or tlb entries.
64  *
65  * There is a special way how to put a range of potentially faulting
66  * insns (like twenty ldd/std's with now intervening other instructions)
67  * You specify address of first in insn and 0 in fixup and in the next
68  * exception_table_entry you specify last potentially faulting insn + 1
69  * and in fixup the routine which should handle the fault.
70  * That fixup code will get
71  * (faulting_insn_address - first_insn_in_the_range_address)/4
72  * in %g2 (ie. index of the faulting instruction in the range).
73  */
74 
75 struct exception_table_entry
76 {
77         unsigned long insn, fixup;
78 };
79 
80 /* Returns 0 if exception not found and fixup otherwise.  */
81 unsigned long search_extables_range(unsigned long addr, unsigned long *g2);
82 
83 void __ret_efault(void);
84 
85 /* Uh, these should become the main single-value transfer routines..
86  * They automatically use the right size if we just have the right
87  * pointer type..
88  *
89  * This gets kind of ugly. We want to return _two_ values in "get_user()"
90  * and yet we don't want to do any pointers, because that is too much
91  * of a performance impact. Thus we have a few rather ugly macros here,
92  * and hide all the ugliness from the user.
93  */
94 #define put_user(x, ptr) ({ \
95 	unsigned long __pu_addr = (unsigned long)(ptr); \
96 	__chk_user_ptr(ptr); \
97 	__put_user_check((__typeof__(*(ptr)))(x), __pu_addr, sizeof(*(ptr))); \
98 })
99 
100 #define get_user(x, ptr) ({ \
101 	unsigned long __gu_addr = (unsigned long)(ptr); \
102 	__chk_user_ptr(ptr); \
103 	__get_user_check((x), __gu_addr, sizeof(*(ptr)), __typeof__(*(ptr))); \
104 })
105 
106 /*
107  * The "__xxx" versions do not do address space checking, useful when
108  * doing multiple accesses to the same area (the user has to do the
109  * checks by hand with "access_ok()")
110  */
111 #define __put_user(x, ptr) \
112 	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
113 #define __get_user(x, ptr) \
114     __get_user_nocheck((x), (ptr), sizeof(*(ptr)), __typeof__(*(ptr)))
115 
116 struct __large_struct { unsigned long buf[100]; };
117 #define __m(x) ((struct __large_struct __user *)(x))
118 
119 #define __put_user_check(x, addr, size) ({ \
120 	register int __pu_ret; \
121 	if (__access_ok(addr, size)) { \
122 		switch (size) { \
123 		case 1: \
124 			__put_user_asm(x, b, addr, __pu_ret); \
125 			break; \
126 		case 2: \
127 			__put_user_asm(x, h, addr, __pu_ret); \
128 			break; \
129 		case 4: \
130 			__put_user_asm(x, , addr, __pu_ret); \
131 			break; \
132 		case 8: \
133 			__put_user_asm(x, d, addr, __pu_ret); \
134 			break; \
135 		default: \
136 			__pu_ret = __put_user_bad(); \
137 			break; \
138 		} \
139 	} else { \
140 		__pu_ret = -EFAULT; \
141 	} \
142 	__pu_ret; \
143 })
144 
145 #define __put_user_nocheck(x, addr, size) ({			\
146 	register int __pu_ret;					\
147 	switch (size) {						\
148 	case 1: __put_user_asm(x, b, addr, __pu_ret); break;	\
149 	case 2: __put_user_asm(x, h, addr, __pu_ret); break;	\
150 	case 4: __put_user_asm(x, , addr, __pu_ret); break;	\
151 	case 8: __put_user_asm(x, d, addr, __pu_ret); break;	\
152 	default: __pu_ret = __put_user_bad(); break;		\
153 	} \
154 	__pu_ret; \
155 })
156 
157 #define __put_user_asm(x, size, addr, ret)				\
158 __asm__ __volatile__(							\
159 		"/* Put user asm, inline. */\n"				\
160 	"1:\t"	"st"#size " %1, %2\n\t"					\
161 		"clr	%0\n"						\
162 	"2:\n\n\t"							\
163 		".section .fixup,#alloc,#execinstr\n\t"			\
164 		".align	4\n"						\
165 	"3:\n\t"							\
166 		"b	2b\n\t"						\
167 		" mov	%3, %0\n\t"					\
168 		".previous\n\n\t"					\
169 		".section __ex_table,#alloc\n\t"			\
170 		".align	4\n\t"						\
171 		".word	1b, 3b\n\t"					\
172 		".previous\n\n\t"					\
173 	       : "=&r" (ret) : "r" (x), "m" (*__m(addr)),		\
174 		 "i" (-EFAULT))
175 
176 int __put_user_bad(void);
177 
178 #define __get_user_check(x, addr, size, type) ({ \
179 	register int __gu_ret; \
180 	register unsigned long __gu_val; \
181 	if (__access_ok(addr, size)) { \
182 		switch (size) { \
183 		case 1: \
184 			 __get_user_asm(__gu_val, ub, addr, __gu_ret); \
185 			break; \
186 		case 2: \
187 			__get_user_asm(__gu_val, uh, addr, __gu_ret); \
188 			break; \
189 		case 4: \
190 			__get_user_asm(__gu_val, , addr, __gu_ret); \
191 			break; \
192 		case 8: \
193 			__get_user_asm(__gu_val, d, addr, __gu_ret); \
194 			break; \
195 		default: \
196 			__gu_val = 0; \
197 			__gu_ret = __get_user_bad(); \
198 			break; \
199 		} \
200 	 } else { \
201 		 __gu_val = 0; \
202 		 __gu_ret = -EFAULT; \
203 	} \
204 	x = (__force type) __gu_val; \
205 	__gu_ret; \
206 })
207 
208 #define __get_user_nocheck(x, addr, size, type) ({			\
209 	register int __gu_ret;						\
210 	register unsigned long __gu_val;				\
211 	switch (size) {							\
212 	case 1: __get_user_asm(__gu_val, ub, addr, __gu_ret); break;	\
213 	case 2: __get_user_asm(__gu_val, uh, addr, __gu_ret); break;	\
214 	case 4: __get_user_asm(__gu_val, , addr, __gu_ret); break;	\
215 	case 8: __get_user_asm(__gu_val, d, addr, __gu_ret); break;	\
216 	default:							\
217 		__gu_val = 0;						\
218 		__gu_ret = __get_user_bad();				\
219 		break;							\
220 	}								\
221 	x = (__force type) __gu_val;					\
222 	__gu_ret;							\
223 })
224 
225 #define __get_user_asm(x, size, addr, ret)				\
226 __asm__ __volatile__(							\
227 		"/* Get user asm, inline. */\n"				\
228 	"1:\t"	"ld"#size " %2, %1\n\t"					\
229 		"clr	%0\n"						\
230 	"2:\n\n\t"							\
231 		".section .fixup,#alloc,#execinstr\n\t"			\
232 		".align	4\n"						\
233 	"3:\n\t"							\
234 		"clr	%1\n\t"						\
235 		"b	2b\n\t"						\
236 		" mov	%3, %0\n\n\t"					\
237 		".previous\n\t"						\
238 		".section __ex_table,#alloc\n\t"			\
239 		".align	4\n\t"						\
240 		".word	1b, 3b\n\n\t"					\
241 		".previous\n\t"						\
242 	       : "=&r" (ret), "=&r" (x) : "m" (*__m(addr)),		\
243 		 "i" (-EFAULT))
244 
245 int __get_user_bad(void);
246 
247 unsigned long __copy_user(void __user *to, const void __user *from, unsigned long size);
248 
249 static inline unsigned long copy_to_user(void __user *to, const void *from, unsigned long n)
250 {
251 	if (n && __access_ok((unsigned long) to, n))
252 		return __copy_user(to, (__force void __user *) from, n);
253 	else
254 		return n;
255 }
256 
257 static inline unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n)
258 {
259 	return __copy_user(to, (__force void __user *) from, n);
260 }
261 
262 static inline unsigned long copy_from_user(void *to, const void __user *from, unsigned long n)
263 {
264 	if (n && __access_ok((unsigned long) from, n))
265 		return __copy_user((__force void __user *) to, from, n);
266 	else
267 		return n;
268 }
269 
270 static inline unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n)
271 {
272 	return __copy_user((__force void __user *) to, from, n);
273 }
274 
275 #define __copy_to_user_inatomic __copy_to_user
276 #define __copy_from_user_inatomic __copy_from_user
277 
278 static inline unsigned long __clear_user(void __user *addr, unsigned long size)
279 {
280 	unsigned long ret;
281 
282 	__asm__ __volatile__ (
283 		".section __ex_table,#alloc\n\t"
284 		".align 4\n\t"
285 		".word 1f,3\n\t"
286 		".previous\n\t"
287 		"mov %2, %%o1\n"
288 		"1:\n\t"
289 		"call __bzero\n\t"
290 		" mov %1, %%o0\n\t"
291 		"mov %%o0, %0\n"
292 		: "=r" (ret) : "r" (addr), "r" (size) :
293 		"o0", "o1", "o2", "o3", "o4", "o5", "o7",
294 		"g1", "g2", "g3", "g4", "g5", "g7", "cc");
295 
296 	return ret;
297 }
298 
299 static inline unsigned long clear_user(void __user *addr, unsigned long n)
300 {
301 	if (n && __access_ok((unsigned long) addr, n))
302 		return __clear_user(addr, n);
303 	else
304 		return n;
305 }
306 
307 __must_check long strlen_user(const char __user *str);
308 __must_check long strnlen_user(const char __user *str, long n);
309 
310 #endif  /* __ASSEMBLY__ */
311 
312 #endif /* _ASM_UACCESS_H */
313