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_ds() (KERNEL_DS) 36 #define get_fs() (current->thread.current_ds) 37 #define set_fs(val) (current->thread.current_ds = (val)) 38 39 #define segment_eq(a, b) ((a).seg == (b).seg) 40 41 #define __kernel_ok (uaccess_kernel()) 42 #define __user_ok(addr, size) \ 43 (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size))) 44 #define __access_ok(addr, size) (__kernel_ok || __user_ok((addr), (size))) 45 #define access_ok(type, addr, size) __access_ok((unsigned long)(addr), (size)) 46 47 #define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE) 48 49 /* 50 * These are the main single-value transfer routines. They 51 * automatically use the right size if we just have the right pointer 52 * type. 53 * 54 * This gets kind of ugly. We want to return _two_ values in 55 * "get_user()" and yet we don't want to do any pointers, because that 56 * is too much of a performance impact. Thus we have a few rather ugly 57 * macros here, and hide all the uglyness from the user. 58 * 59 * Careful to not 60 * (a) re-use the arguments for side effects (sizeof is ok) 61 * (b) require any knowledge of processes at this stage 62 */ 63 #define put_user(x, ptr) __put_user_check((x), (ptr), sizeof(*(ptr))) 64 #define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr))) 65 66 /* 67 * The "__xxx" versions of the user access functions are versions that 68 * do not verify the address space, that must have been done previously 69 * with a separate "access_ok()" call (this is used when we do multiple 70 * accesses to the same area of user memory). 71 */ 72 #define __put_user(x, ptr) __put_user_nocheck((x), (ptr), sizeof(*(ptr))) 73 #define __get_user(x, ptr) __get_user_nocheck((x), (ptr), sizeof(*(ptr))) 74 75 76 extern long __put_user_bad(void); 77 78 #define __put_user_nocheck(x, ptr, size) \ 79 ({ \ 80 long __pu_err; \ 81 __put_user_size((x), (ptr), (size), __pu_err); \ 82 __pu_err; \ 83 }) 84 85 #define __put_user_check(x, ptr, size) \ 86 ({ \ 87 long __pu_err = -EFAULT; \ 88 __typeof__(*(ptr)) *__pu_addr = (ptr); \ 89 if (access_ok(VERIFY_WRITE, __pu_addr, size)) \ 90 __put_user_size((x), __pu_addr, (size), __pu_err); \ 91 __pu_err; \ 92 }) 93 94 #define __put_user_size(x, ptr, size, retval) \ 95 do { \ 96 int __cb; \ 97 retval = 0; \ 98 switch (size) { \ 99 case 1: __put_user_asm(x, ptr, retval, 1, "s8i", __cb); break; \ 100 case 2: __put_user_asm(x, ptr, retval, 2, "s16i", __cb); break; \ 101 case 4: __put_user_asm(x, ptr, retval, 4, "s32i", __cb); break; \ 102 case 8: { \ 103 __typeof__(*ptr) __v64 = x; \ 104 retval = __copy_to_user(ptr, &__v64, 8); \ 105 break; \ 106 } \ 107 default: __put_user_bad(); \ 108 } \ 109 } while (0) 110 111 112 /* 113 * Consider a case of a user single load/store would cause both an 114 * unaligned exception and an MMU-related exception (unaligned 115 * exceptions happen first): 116 * 117 * User code passes a bad variable ptr to a system call. 118 * Kernel tries to access the variable. 119 * Unaligned exception occurs. 120 * Unaligned exception handler tries to make aligned accesses. 121 * Double exception occurs for MMU-related cause (e.g., page not mapped). 122 * do_page_fault() thinks the fault address belongs to the kernel, not the 123 * user, and panics. 124 * 125 * The kernel currently prohibits user unaligned accesses. We use the 126 * __check_align_* macros to check for unaligned addresses before 127 * accessing user space so we don't crash the kernel. Both 128 * __put_user_asm and __get_user_asm use these alignment macros, so 129 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in 130 * sync. 131 */ 132 133 #define __check_align_1 "" 134 135 #define __check_align_2 \ 136 " _bbci.l %3, 0, 1f \n" \ 137 " movi %0, %4 \n" \ 138 " _j 2f \n" 139 140 #define __check_align_4 \ 141 " _bbsi.l %3, 0, 0f \n" \ 142 " _bbci.l %3, 1, 1f \n" \ 143 "0: movi %0, %4 \n" \ 144 " _j 2f \n" 145 146 147 /* 148 * We don't tell gcc that we are accessing memory, but this is OK 149 * because we do not write to any memory gcc knows about, so there 150 * are no aliasing issues. 151 * 152 * WARNING: If you modify this macro at all, verify that the 153 * __check_align_* macros still work. 154 */ 155 #define __put_user_asm(x, addr, err, align, insn, cb) \ 156 __asm__ __volatile__( \ 157 __check_align_##align \ 158 "1: "insn" %2, %3, 0 \n" \ 159 "2: \n" \ 160 " .section .fixup,\"ax\" \n" \ 161 " .align 4 \n" \ 162 "4: \n" \ 163 " .long 2b \n" \ 164 "5: \n" \ 165 " l32r %1, 4b \n" \ 166 " movi %0, %4 \n" \ 167 " jx %1 \n" \ 168 " .previous \n" \ 169 " .section __ex_table,\"a\" \n" \ 170 " .long 1b, 5b \n" \ 171 " .previous" \ 172 :"=r" (err), "=r" (cb) \ 173 :"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err)) 174 175 #define __get_user_nocheck(x, ptr, size) \ 176 ({ \ 177 long __gu_err, __gu_val; \ 178 __get_user_size(__gu_val, (ptr), (size), __gu_err); \ 179 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 180 __gu_err; \ 181 }) 182 183 #define __get_user_check(x, ptr, size) \ 184 ({ \ 185 long __gu_err = -EFAULT, __gu_val = 0; \ 186 const __typeof__(*(ptr)) *__gu_addr = (ptr); \ 187 if (access_ok(VERIFY_READ, __gu_addr, size)) \ 188 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ 189 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 190 __gu_err; \ 191 }) 192 193 extern long __get_user_bad(void); 194 195 #define __get_user_size(x, ptr, size, retval) \ 196 do { \ 197 int __cb; \ 198 retval = 0; \ 199 switch (size) { \ 200 case 1: __get_user_asm(x, ptr, retval, 1, "l8ui", __cb); break;\ 201 case 2: __get_user_asm(x, ptr, retval, 2, "l16ui", __cb); break;\ 202 case 4: __get_user_asm(x, ptr, retval, 4, "l32i", __cb); break;\ 203 case 8: retval = __copy_from_user(&x, ptr, 8); break; \ 204 default: (x) = __get_user_bad(); \ 205 } \ 206 } while (0) 207 208 209 /* 210 * WARNING: If you modify this macro at all, verify that the 211 * __check_align_* macros still work. 212 */ 213 #define __get_user_asm(x, addr, err, align, insn, cb) \ 214 __asm__ __volatile__( \ 215 __check_align_##align \ 216 "1: "insn" %2, %3, 0 \n" \ 217 "2: \n" \ 218 " .section .fixup,\"ax\" \n" \ 219 " .align 4 \n" \ 220 "4: \n" \ 221 " .long 2b \n" \ 222 "5: \n" \ 223 " l32r %1, 4b \n" \ 224 " movi %2, 0 \n" \ 225 " movi %0, %4 \n" \ 226 " jx %1 \n" \ 227 " .previous \n" \ 228 " .section __ex_table,\"a\" \n" \ 229 " .long 1b, 5b \n" \ 230 " .previous" \ 231 :"=r" (err), "=r" (cb), "=r" (x) \ 232 :"r" (addr), "i" (-EFAULT), "0" (err)) 233 234 235 /* 236 * Copy to/from user space 237 */ 238 239 extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n); 240 241 static inline unsigned long 242 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 243 { 244 prefetchw(to); 245 return __xtensa_copy_user(to, (__force const void *)from, n); 246 } 247 static inline unsigned long 248 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 249 { 250 prefetch(from); 251 return __xtensa_copy_user((__force void *)to, from, n); 252 } 253 #define INLINE_COPY_FROM_USER 254 #define INLINE_COPY_TO_USER 255 256 /* 257 * We need to return the number of bytes not cleared. Our memset() 258 * returns zero if a problem occurs while accessing user-space memory. 259 * In that event, return no memory cleared. Otherwise, zero for 260 * success. 261 */ 262 263 static inline unsigned long 264 __xtensa_clear_user(void *addr, unsigned long size) 265 { 266 if (!__memset(addr, 0, size)) 267 return size; 268 return 0; 269 } 270 271 static inline unsigned long 272 clear_user(void *addr, unsigned long size) 273 { 274 if (access_ok(VERIFY_WRITE, addr, size)) 275 return __xtensa_clear_user(addr, size); 276 return size ? -EFAULT : 0; 277 } 278 279 #define __clear_user __xtensa_clear_user 280 281 282 #ifndef CONFIG_GENERIC_STRNCPY_FROM_USER 283 284 extern long __strncpy_user(char *, const char *, long); 285 286 static inline long 287 strncpy_from_user(char *dst, const char *src, long count) 288 { 289 if (access_ok(VERIFY_READ, src, 1)) 290 return __strncpy_user(dst, src, count); 291 return -EFAULT; 292 } 293 #else 294 long strncpy_from_user(char *dst, const char *src, long count); 295 #endif 296 297 /* 298 * Return the size of a string (including the ending 0!) 299 */ 300 extern long __strnlen_user(const char *, long); 301 302 static inline long strnlen_user(const char *str, long len) 303 { 304 unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1; 305 306 if ((unsigned long)str > top) 307 return 0; 308 return __strnlen_user(str, len); 309 } 310 311 #endif /* _XTENSA_UACCESS_H */ 312