summaryrefslogtreecommitdiffstats
path: root/arch/xtensa/include/asm/uaccess.h
blob: 848a3d736bcbfb0909723114451ccf2fc2b48e83 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
/*
 * include/asm-xtensa/uaccess.h
 *
 * User space memory access functions
 *
 * These routines provide basic accessing functions to the user memory
 * space for the kernel. This header file provides functions such as:
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001 - 2005 Tensilica Inc.
 */

#ifndef _XTENSA_UACCESS_H
#define _XTENSA_UACCESS_H

#include <linux/errno.h>
#include <linux/prefetch.h>
#include <asm/types.h>

#define VERIFY_READ    0
#define VERIFY_WRITE   1

#include <linux/sched.h>

/*
 * The fs value determines whether argument validity checking should
 * be performed or not.  If get_fs() == USER_DS, checking is
 * performed, with get_fs() == KERNEL_DS, checking is bypassed.
 *
 * For historical reasons (Data Segment Register?), these macros are
 * grossly misnamed.
 */

#define KERNEL_DS	((mm_segment_t) { 0 })
#define USER_DS		((mm_segment_t) { 1 })

#define get_ds()	(KERNEL_DS)
#define get_fs()	(current->thread.current_ds)
#define set_fs(val)	(current->thread.current_ds = (val))

#define segment_eq(a, b)	((a).seg == (b).seg)

#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
#define __user_ok(addr, size) \
		(((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
#define __access_ok(addr, size) (__kernel_ok || __user_ok((addr), (size)))
#define access_ok(type, addr, size) __access_ok((unsigned long)(addr), (size))

/*
 * These are the main single-value transfer routines.  They
 * automatically use the right size if we just have the right pointer
 * type.
 *
 * This gets kind of ugly. We want to return _two_ values in
 * "get_user()" and yet we don't want to do any pointers, because that
 * is too much of a performance impact. Thus we have a few rather ugly
 * macros here, and hide all the uglyness from the user.
 *
 * Careful to not
 * (a) re-use the arguments for side effects (sizeof is ok)
 * (b) require any knowledge of processes at this stage
 */
#define put_user(x, ptr)	__put_user_check((x), (ptr), sizeof(*(ptr)))
#define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr)))

/*
 * The "__xxx" versions of the user access functions are versions that
 * do not verify the address space, that must have been done previously
 * with a separate "access_ok()" call (this is used when we do multiple
 * accesses to the same area of user memory).
 */
#define __put_user(x, ptr) __put_user_nocheck((x), (ptr), sizeof(*(ptr)))
#define __get_user(x, ptr) __get_user_nocheck((x), (ptr), sizeof(*(ptr)))


extern long __put_user_bad(void);

#define __put_user_nocheck(x, ptr, size)		\
({							\
	long __pu_err;					\
	__put_user_size((x), (ptr), (size), __pu_err);	\
	__pu_err;					\
})

#define __put_user_check(x, ptr, size)					\
({									\
	long __pu_err = -EFAULT;					\
	__typeof__(*(ptr)) *__pu_addr = (ptr);				\
	if (access_ok(VERIFY_WRITE, __pu_addr, size))			\
		__put_user_size((x), __pu_addr, (size), __pu_err);	\
	__pu_err;							\
})

#define __put_user_size(x, ptr, size, retval)				\
do {									\
	int __cb;							\
	retval = 0;							\
	switch (size) {							\
	case 1: __put_user_asm(x, ptr, retval, 1, "s8i", __cb);  break;	\
	case 2: __put_user_asm(x, ptr, retval, 2, "s16i", __cb); break;	\
	case 4: __put_user_asm(x, ptr, retval, 4, "s32i", __cb); break;	\
	case 8: {							\
		     __typeof__(*ptr) __v64 = x;			\
		     retval = __copy_to_user(ptr, &__v64, 8);		\
		     break;						\
	        }							\
	default: __put_user_bad();					\
	}								\
} while (0)


/*
 * Consider a case of a user single load/store would cause both an
 * unaligned exception and an MMU-related exception (unaligned
 * exceptions happen first):
 *
 * User code passes a bad variable ptr to a system call.
 * Kernel tries to access the variable.
 * Unaligned exception occurs.
 * Unaligned exception handler tries to make aligned accesses.
 * Double exception occurs for MMU-related cause (e.g., page not mapped).
 * do_page_fault() thinks the fault address belongs to the kernel, not the
 * user, and panics.
 *
 * The kernel currently prohibits user unaligned accesses.  We use the
 * __check_align_* macros to check for unaligned addresses before
 * accessing user space so we don't crash the kernel.  Both
 * __put_user_asm and __get_user_asm use these alignment macros, so
 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
 * sync.
 */

#define __check_align_1  ""

#define __check_align_2				\
	"   _bbci.l %3,  0, 1f		\n"	\
	"   movi    %0, %4		\n"	\
	"   _j      2f			\n"

#define __check_align_4				\
	"   _bbsi.l %3,  0, 0f		\n"	\
	"   _bbci.l %3,  1, 1f		\n"	\
	"0: movi    %0, %4		\n"	\
	"   _j      2f			\n"


/*
 * We don't tell gcc that we are accessing memory, but this is OK
 * because we do not write to any memory gcc knows about, so there
 * are no aliasing issues.
 *
 * WARNING: If you modify this macro at all, verify that the
 * __check_align_* macros still work.
 */
#define __put_user_asm(x, addr, err, align, insn, cb)	\
__asm__ __volatile__(					\
	__check_align_##align				\
	"1: "insn"  %2, %3, 0		\n"		\
	"2:				\n"		\
	"   .section  .fixup,\"ax\"	\n"		\
	"   .align 4			\n"		\
	"4:				\n"		\
	"   .long  2b			\n"		\
	"5:				\n"		\
	"   l32r   %1, 4b		\n"		\
	"   movi   %0, %4		\n"		\
	"   jx     %1			\n"		\
	"   .previous			\n"		\
	"   .section  __ex_table,\"a\"	\n"		\
	"   .long	1b, 5b		\n"		\
	"   .previous"					\
	:"=r" (err), "=r" (cb)				\
	:"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))

#define __get_user_nocheck(x, ptr, size)			\
({								\
	long __gu_err, __gu_val;				\
	__get_user_size(__gu_val, (ptr), (size), __gu_err);	\
	(x) = (__force __typeof__(*(ptr)))__gu_val;		\
	__gu_err;						\
})

#define __get_user_check(x, ptr, size)					\
({									\
	long __gu_err = -EFAULT, __gu_val = 0;				\
	const __typeof__(*(ptr)) *__gu_addr = (ptr);			\
	if (access_ok(VERIFY_READ, __gu_addr, size))			\
		__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
	__gu_err;							\
})

extern long __get_user_bad(void);

#define __get_user_size(x, ptr, size, retval)				\
do {									\
	int __cb;							\
	retval = 0;							\
	switch (size) {							\
	case 1: __get_user_asm(x, ptr, retval, 1, "l8ui", __cb);  break;\
	case 2: __get_user_asm(x, ptr, retval, 2, "l16ui", __cb); break;\
	case 4: __get_user_asm(x, ptr, retval, 4, "l32i", __cb);  break;\
	case 8: retval = __copy_from_user(&x, ptr, 8);    break;	\
	default: (x) = __get_user_bad();				\
	}								\
} while (0)


/*
 * WARNING: If you modify this macro at all, verify that the
 * __check_align_* macros still work.
 */
#define __get_user_asm(x, addr, err, align, insn, cb) \
__asm__ __volatile__(			\
	__check_align_##align			\
	"1: "insn"  %2, %3, 0		\n"	\
	"2:				\n"	\
	"   .section  .fixup,\"ax\"	\n"	\
	"   .align 4			\n"	\
	"4:				\n"	\
	"   .long  2b			\n"	\
	"5:				\n"	\
	"   l32r   %1, 4b		\n"	\
	"   movi   %2, 0		\n"	\
	"   movi   %0, %4		\n"	\
	"   jx     %1			\n"	\
	"   .previous			\n"	\
	"   .section  __ex_table,\"a\"	\n"	\
	"   .long	1b, 5b		\n"	\
	"   .previous"				\
	:"=r" (err), "=r" (cb), "=r" (x)	\
	:"r" (addr), "i" (-EFAULT), "0" (err))


/*
 * Copy to/from user space
 */

/*
 * We use a generic, arbitrary-sized copy subroutine.  The Xtensa
 * architecture would cause heavy code bloat if we tried to inline
 * these functions and provide __constant_copy_* equivalents like the
 * i386 versions.  __xtensa_copy_user is quite efficient.  See the
 * .fixup section of __xtensa_copy_user for a discussion on the
 * X_zeroing equivalents for Xtensa.
 */

extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
#define __copy_user(to, from, size) __xtensa_copy_user(to, from, size)


static inline unsigned long
__generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n)
{
	return __copy_user(to, from, n);
}

static inline unsigned long
__generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n)
{
	return __copy_user(to, from, n);
}

static inline unsigned long
__generic_copy_to_user(void *to, const void *from, unsigned long n)
{
	prefetch(from);
	if (access_ok(VERIFY_WRITE, to, n))
		return __copy_user(to, from, n);
	return n;
}

static inline unsigned long
__generic_copy_from_user(void *to, const void *from, unsigned long n)
{
	prefetchw(to);
	if (access_ok(VERIFY_READ, from, n))
		return __copy_user(to, from, n);
	else
		memset(to, 0, n);
	return n;
}

#define copy_to_user(to, from, n) __generic_copy_to_user((to), (from), (n))
#define copy_from_user(to, from, n) __generic_copy_from_user((to), (from), (n))
#define __copy_to_user(to, from, n) \
	__generic_copy_to_user_nocheck((to), (from), (n))
#define __copy_from_user(to, from, n) \
	__generic_copy_from_user_nocheck((to), (from), (n))
#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user


/*
 * We need to return the number of bytes not cleared.  Our memset()
 * returns zero if a problem occurs while accessing user-space memory.
 * In that event, return no memory cleared.  Otherwise, zero for
 * success.
 */

static inline unsigned long
__xtensa_clear_user(void *addr, unsigned long size)
{
	if ( ! memset(addr, 0, size) )
		return size;
	return 0;
}

static inline unsigned long
clear_user(void *addr, unsigned long size)
{
	if (access_ok(VERIFY_WRITE, addr, size))
		return __xtensa_clear_user(addr, size);
	return size ? -EFAULT : 0;
}

#define __clear_user  __xtensa_clear_user


extern long __strncpy_user(char *, const char *, long);
#define __strncpy_from_user __strncpy_user

static inline long
strncpy_from_user(char *dst, const char *src, long count)
{
	if (access_ok(VERIFY_READ, src, 1))
		return __strncpy_from_user(dst, src, count);
	return -EFAULT;
}


#define strlen_user(str) strnlen_user((str), TASK_SIZE - 1)

/*
 * Return the size of a string (including the ending 0!)
 */
extern long __strnlen_user(const char *, long);

static inline long strnlen_user(const char *str, long len)
{
	unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1;

	if ((unsigned long)str > top)
		return 0;
	return __strnlen_user(str, len);
}


struct exception_table_entry
{
	unsigned long insn, fixup;
};

#endif	/* _XTENSA_UACCESS_H */