1/*
2 * include/asm-xtensa/uaccess.h
3 *
4 * User space memory access functions
5 *
6 * These routines provide basic accessing functions to the user memory
7 * space for the kernel. This header file provides functions such as:
8 *
9 * This file is subject to the terms and conditions of the GNU General Public
10 * License.  See the file "COPYING" in the main directory of this archive
11 * for more details.
12 *
13 * Copyright (C) 2001 - 2005 Tensilica Inc.
14 */
15
16#ifndef _XTENSA_UACCESS_H
17#define _XTENSA_UACCESS_H
18
19#include <linux/prefetch.h>
20#include <asm/types.h>
21#include <asm/extable.h>
22
23/*
24 * The fs value determines whether argument validity checking should
25 * be performed or not.  If get_fs() == USER_DS, checking is
26 * performed, with get_fs() == KERNEL_DS, checking is bypassed.
27 *
28 * For historical reasons (Data Segment Register?), these macros are
29 * grossly misnamed.
30 */
31
32#define KERNEL_DS	((mm_segment_t) { 0 })
33#define USER_DS		((mm_segment_t) { 1 })
34
35#define get_fs()	(current->thread.current_ds)
36#define set_fs(val)	(current->thread.current_ds = (val))
37
38#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
39
40#define __kernel_ok (uaccess_kernel())
41#define __user_ok(addr, size) \
42		(((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
43#define __access_ok(addr, size) (__kernel_ok || __user_ok((addr), (size)))
44#define access_ok(addr, size) __access_ok((unsigned long)(addr), (size))
45
46#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
47
48/*
49 * These are the main single-value transfer routines.  They
50 * automatically use the right size if we just have the right pointer
51 * type.
52 *
53 * This gets kind of ugly. We want to return _two_ values in
54 * "get_user()" and yet we don't want to do any pointers, because that
55 * is too much of a performance impact. Thus we have a few rather ugly
56 * macros here, and hide all the uglyness from the user.
57 *
58 * Careful to not
59 * (a) re-use the arguments for side effects (sizeof is ok)
60 * (b) require any knowledge of processes at this stage
61 */
62#define put_user(x, ptr)	__put_user_check((x), (ptr), sizeof(*(ptr)))
63#define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr)))
64
65/*
66 * The "__xxx" versions of the user access functions are versions that
67 * do not verify the address space, that must have been done previously
68 * with a separate "access_ok()" call (this is used when we do multiple
69 * accesses to the same area of user memory).
70 */
71#define __put_user(x, ptr) __put_user_nocheck((x), (ptr), sizeof(*(ptr)))
72#define __get_user(x, ptr) __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
73
74
75extern long __put_user_bad(void);
76
77#define __put_user_nocheck(x, ptr, size)		\
78({							\
79	long __pu_err;					\
80	__put_user_size((x), (ptr), (size), __pu_err);	\
81	__pu_err;					\
82})
83
84#define __put_user_check(x, ptr, size)					\
85({									\
86	long __pu_err = -EFAULT;					\
87	__typeof__(*(ptr)) __user *__pu_addr = (ptr);			\
88	if (access_ok(__pu_addr, size))			\
89		__put_user_size((x), __pu_addr, (size), __pu_err);	\
90	__pu_err;							\
91})
92
93#define __put_user_size(x, ptr, size, retval)				\
94do {									\
95	int __cb;							\
96	retval = 0;							\
97	switch (size) {							\
98	case 1: __put_user_asm(x, ptr, retval, 1, "s8i", __cb);  break;	\
99	case 2: __put_user_asm(x, ptr, retval, 2, "s16i", __cb); break;	\
100	case 4: __put_user_asm(x, ptr, retval, 4, "s32i", __cb); break;	\
101	case 8: {							\
102		     __typeof__(*ptr) __v64 = x;			\
103		     retval = __copy_to_user(ptr, &__v64, 8) ? -EFAULT : 0;	\
104		     break;						\
105	        }							\
106	default: __put_user_bad();					\
107	}								\
108} while (0)
109
110
111/*
112 * Consider a case of a user single load/store would cause both an
113 * unaligned exception and an MMU-related exception (unaligned
114 * exceptions happen first):
115 *
116 * User code passes a bad variable ptr to a system call.
117 * Kernel tries to access the variable.
118 * Unaligned exception occurs.
119 * Unaligned exception handler tries to make aligned accesses.
120 * Double exception occurs for MMU-related cause (e.g., page not mapped).
121 * do_page_fault() thinks the fault address belongs to the kernel, not the
122 * user, and panics.
123 *
124 * The kernel currently prohibits user unaligned accesses.  We use the
125 * __check_align_* macros to check for unaligned addresses before
126 * accessing user space so we don't crash the kernel.  Both
127 * __put_user_asm and __get_user_asm use these alignment macros, so
128 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
129 * sync.
130 */
131
132#define __check_align_1  ""
133
134#define __check_align_2				\
135	"   _bbci.l %[mem] * 0, 1f	\n"	\
136	"   movi    %[err], %[efault]	\n"	\
137	"   _j      2f			\n"
138
139#define __check_align_4				\
140	"   _bbsi.l %[mem] * 0, 0f	\n"	\
141	"   _bbci.l %[mem] * 0 + 1, 1f	\n"	\
142	"0: movi    %[err], %[efault]	\n"	\
143	"   _j      2f			\n"
144
145
146/*
147 * We don't tell gcc that we are accessing memory, but this is OK
148 * because we do not write to any memory gcc knows about, so there
149 * are no aliasing issues.
150 *
151 * WARNING: If you modify this macro at all, verify that the
152 * __check_align_* macros still work.
153 */
154#define __put_user_asm(x_, addr_, err_, align, insn, cb)\
155__asm__ __volatile__(					\
156	__check_align_##align				\
157	"1: "insn"  %[x], %[mem]	\n"		\
158	"2:				\n"		\
159	"   .section  .fixup,\"ax\"	\n"		\
160	"   .align 4			\n"		\
161	"   .literal_position		\n"		\
162	"5:				\n"		\
163	"   movi   %[tmp], 2b		\n"		\
164	"   movi   %[err], %[efault]	\n"		\
165	"   jx     %[tmp]		\n"		\
166	"   .previous			\n"		\
167	"   .section  __ex_table,\"a\"	\n"		\
168	"   .long	1b, 5b		\n"		\
169	"   .previous"					\
170	:[err] "+r"(err_), [tmp] "=r"(cb), [mem] "=m"(*(addr_))		\
171	:[x] "r"(x_), [efault] "i"(-EFAULT))
172
173#define __get_user_nocheck(x, ptr, size)			\
174({								\
175	long __gu_err;						\
176	__get_user_size((x), (ptr), (size), __gu_err);		\
177	__gu_err;						\
178})
179
180#define __get_user_check(x, ptr, size)					\
181({									\
182	long __gu_err = -EFAULT;					\
183	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);		\
184	if (access_ok(__gu_addr, size))					\
185		__get_user_size((x), __gu_addr, (size), __gu_err);	\
186	else								\
187		(x) = (__typeof__(*(ptr)))0;				\
188	__gu_err;							\
189})
190
191extern long __get_user_bad(void);
192
193#define __get_user_size(x, ptr, size, retval)				\
194do {									\
195	int __cb;							\
196	retval = 0;							\
197	switch (size) {							\
198	case 1: __get_user_asm(x, ptr, retval, 1, "l8ui", __cb);  break;\
199	case 2: __get_user_asm(x, ptr, retval, 2, "l16ui", __cb); break;\
200	case 4: __get_user_asm(x, ptr, retval, 4, "l32i", __cb);  break;\
201	case 8: {							\
202		u64 __x;						\
203		if (unlikely(__copy_from_user(&__x, ptr, 8))) {		\
204			retval = -EFAULT;				\
205			(x) = (__typeof__(*(ptr)))0;			\
206		} else {						\
207			(x) = *(__force __typeof__(*(ptr)) *)&__x;	\
208		}							\
209		break;							\
210	}								\
211	default:							\
212		(x) = (__typeof__(*(ptr)))0;				\
213		__get_user_bad();					\
214	}								\
215} while (0)
216
217
218/*
219 * WARNING: If you modify this macro at all, verify that the
220 * __check_align_* macros still work.
221 */
222#define __get_user_asm(x_, addr_, err_, align, insn, cb) \
223do {							\
224	u32 __x = 0;					\
225	__asm__ __volatile__(				\
226		__check_align_##align			\
227		"1: "insn"  %[x], %[mem]	\n"	\
228		"2:				\n"	\
229		"   .section  .fixup,\"ax\"	\n"	\
230		"   .align 4			\n"	\
231		"   .literal_position		\n"	\
232		"5:				\n"	\
233		"   movi   %[tmp], 2b		\n"	\
234		"   movi   %[err], %[efault]	\n"	\
235		"   jx     %[tmp]		\n"	\
236		"   .previous			\n"	\
237		"   .section  __ex_table,\"a\"	\n"	\
238		"   .long	1b, 5b		\n"	\
239		"   .previous"				\
240		:[err] "+r"(err_), [tmp] "=r"(cb), [x] "+r"(__x) \
241		:[mem] "m"(*(addr_)), [efault] "i"(-EFAULT)); \
242	(x_) = (__force __typeof__(*(addr_)))__x;	\
243} while (0)
244
245
246/*
247 * Copy to/from user space
248 */
249
250extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
251
252static inline unsigned long
253raw_copy_from_user(void *to, const void __user *from, unsigned long n)
254{
255	prefetchw(to);
256	return __xtensa_copy_user(to, (__force const void *)from, n);
257}
258static inline unsigned long
259raw_copy_to_user(void __user *to, const void *from, unsigned long n)
260{
261	prefetch(from);
262	return __xtensa_copy_user((__force void *)to, from, n);
263}
264#define INLINE_COPY_FROM_USER
265#define INLINE_COPY_TO_USER
266
267/*
268 * We need to return the number of bytes not cleared.  Our memset()
269 * returns zero if a problem occurs while accessing user-space memory.
270 * In that event, return no memory cleared.  Otherwise, zero for
271 * success.
272 */
273
274static inline unsigned long
275__xtensa_clear_user(void __user *addr, unsigned long size)
276{
277	if (!__memset((void __force *)addr, 0, size))
278		return size;
279	return 0;
280}
281
282static inline unsigned long
283clear_user(void __user *addr, unsigned long size)
284{
285	if (access_ok(addr, size))
286		return __xtensa_clear_user(addr, size);
287	return size ? -EFAULT : 0;
288}
289
290#define __clear_user  __xtensa_clear_user
291
292
293#ifndef CONFIG_GENERIC_STRNCPY_FROM_USER
294
295extern long __strncpy_user(char *dst, const char __user *src, long count);
296
297static inline long
298strncpy_from_user(char *dst, const char __user *src, long count)
299{
300	if (access_ok(src, 1))
301		return __strncpy_user(dst, src, count);
302	return -EFAULT;
303}
304#else
305long strncpy_from_user(char *dst, const char __user *src, long count);
306#endif
307
308/*
309 * Return the size of a string (including the ending 0!)
310 */
311extern long __strnlen_user(const char __user *str, long len);
312
313static inline long strnlen_user(const char __user *str, long len)
314{
315	if (!access_ok(str, 1))
316		return 0;
317	return __strnlen_user(str, len);
318}
319
320#endif	/* _XTENSA_UACCESS_H */
321