2 * include/asm-xtensa/uaccess.h
4 * User space memory access functions
6 * These routines provide basic accessing functions to the user memory
7 * space for the kernel. This header file provides functions such as:
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
13 * Copyright (C) 2001 - 2005 Tensilica Inc.
16 #ifndef _XTENSA_UACCESS_H
17 #define _XTENSA_UACCESS_H
19 #include <linux/prefetch.h>
20 #include <asm/types.h>
21 #include <asm/extable.h>
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.
28 * For historical reasons (Data Segment Register?), these macros are
32 #define KERNEL_DS ((mm_segment_t) { 0 })
33 #define USER_DS ((mm_segment_t) { 1 })
35 #define get_fs() (current->thread.current_ds)
36 #define set_fs(val) (current->thread.current_ds = (val))
38 #define segment_eq(a, b) ((a).seg == (b).seg)
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))
46 #define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
49 * These are the main single-value transfer routines. They
50 * automatically use the right size if we just have the right pointer
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.
59 * (a) re-use the arguments for side effects (sizeof is ok)
60 * (b) require any knowledge of processes at this stage
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)))
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).
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)))
75 extern long __put_user_bad(void);
77 #define __put_user_nocheck(x, ptr, size) \
80 __put_user_size((x), (ptr), (size), __pu_err); \
84 #define __put_user_check(x, ptr, size) \
86 long __pu_err = -EFAULT; \
87 __typeof__(*(ptr)) *__pu_addr = (ptr); \
88 if (access_ok(__pu_addr, size)) \
89 __put_user_size((x), __pu_addr, (size), __pu_err); \
93 #define __put_user_size(x, ptr, size, retval) \
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; \
102 __typeof__(*ptr) __v64 = x; \
103 retval = __copy_to_user(ptr, &__v64, 8) ? -EFAULT : 0; \
106 default: __put_user_bad(); \
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):
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
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
132 #define __check_align_1 ""
134 #define __check_align_2 \
135 " _bbci.l %3, 0, 1f \n" \
139 #define __check_align_4 \
140 " _bbsi.l %3, 0, 0f \n" \
141 " _bbci.l %3, 1, 1f \n" \
142 "0: movi %0, %4 \n" \
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.
151 * WARNING: If you modify this macro at all, verify that the
152 * __check_align_* macros still work.
154 #define __put_user_asm(x, addr, err, align, insn, cb) \
155 __asm__ __volatile__( \
156 __check_align_##align \
157 "1: "insn" %2, %3, 0 \n" \
159 " .section .fixup,\"ax\" \n" \
161 " .literal_position \n" \
167 " .section __ex_table,\"a\" \n" \
170 :"=r" (err), "=r" (cb) \
171 :"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))
173 #define __get_user_nocheck(x, ptr, size) \
175 long __gu_err, __gu_val; \
176 __get_user_size(__gu_val, (ptr), (size), __gu_err); \
177 (x) = (__force __typeof__(*(ptr)))__gu_val; \
181 #define __get_user_check(x, ptr, size) \
183 long __gu_err = -EFAULT, __gu_val = 0; \
184 const __typeof__(*(ptr)) *__gu_addr = (ptr); \
185 if (access_ok(__gu_addr, size)) \
186 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
187 (x) = (__force __typeof__(*(ptr)))__gu_val; \
191 extern long __get_user_bad(void);
193 #define __get_user_size(x, ptr, size, retval) \
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;\
203 if (unlikely(__copy_from_user(&__x, ptr, 8))) { \
207 (x) = *(__force __typeof__((ptr)))&__x; \
211 default: (x) = __get_user_bad(); \
217 * WARNING: If you modify this macro at all, verify that the
218 * __check_align_* macros still work.
220 #define __get_user_asm(x, addr, err, align, insn, cb) \
221 __asm__ __volatile__( \
222 __check_align_##align \
223 "1: "insn" %2, %3, 0 \n" \
225 " .section .fixup,\"ax\" \n" \
227 " .literal_position \n" \
234 " .section __ex_table,\"a\" \n" \
237 :"=r" (err), "=r" (cb), "=r" (x) \
238 :"r" (addr), "i" (-EFAULT), "0" (err))
242 * Copy to/from user space
245 extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
247 static inline unsigned long
248 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
251 return __xtensa_copy_user(to, (__force const void *)from, n);
253 static inline unsigned long
254 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
257 return __xtensa_copy_user((__force void *)to, from, n);
259 #define INLINE_COPY_FROM_USER
260 #define INLINE_COPY_TO_USER
263 * We need to return the number of bytes not cleared. Our memset()
264 * returns zero if a problem occurs while accessing user-space memory.
265 * In that event, return no memory cleared. Otherwise, zero for
269 static inline unsigned long
270 __xtensa_clear_user(void *addr, unsigned long size)
272 if (!__memset(addr, 0, size))
277 static inline unsigned long
278 clear_user(void *addr, unsigned long size)
280 if (access_ok(addr, size))
281 return __xtensa_clear_user(addr, size);
282 return size ? -EFAULT : 0;
285 #define __clear_user __xtensa_clear_user
288 #ifndef CONFIG_GENERIC_STRNCPY_FROM_USER
290 extern long __strncpy_user(char *, const char *, long);
293 strncpy_from_user(char *dst, const char *src, long count)
295 if (access_ok(src, 1))
296 return __strncpy_user(dst, src, count);
300 long strncpy_from_user(char *dst, const char *src, long count);
304 * Return the size of a string (including the ending 0!)
306 extern long __strnlen_user(const char *, long);
308 static inline long strnlen_user(const char *str, long len)
310 unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1;
312 if ((unsigned long)str > top)
314 return __strnlen_user(str, len);
317 #endif /* _XTENSA_UACCESS_H */