1 /* 2 * Based on arch/arm/include/asm/uaccess.h 3 * 4 * Copyright (C) 2012 ARM Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 #ifndef __ASM_UACCESS_H 19 #define __ASM_UACCESS_H 20 21 /* 22 * User space memory access functions 23 */ 24 #include <linux/string.h> 25 #include <linux/thread_info.h> 26 27 #include <asm/ptrace.h> 28 #include <asm/errno.h> 29 #include <asm/memory.h> 30 #include <asm/compiler.h> 31 32 #define VERIFY_READ 0 33 #define VERIFY_WRITE 1 34 35 /* 36 * The exception table consists of pairs of addresses: the first is the 37 * address of an instruction that is allowed to fault, and the second is 38 * the address at which the program should continue. No registers are 39 * modified, so it is entirely up to the continuation code to figure out 40 * what to do. 41 * 42 * All the routines below use bits of fixup code that are out of line 43 * with the main instruction path. This means when everything is well, 44 * we don't even have to jump over them. Further, they do not intrude 45 * on our cache or tlb entries. 46 */ 47 48 struct exception_table_entry 49 { 50 unsigned long insn, fixup; 51 }; 52 53 extern int fixup_exception(struct pt_regs *regs); 54 55 #define KERNEL_DS (-1UL) 56 #define get_ds() (KERNEL_DS) 57 58 #define USER_DS TASK_SIZE_64 59 #define get_fs() (current_thread_info()->addr_limit) 60 61 static inline void set_fs(mm_segment_t fs) 62 { 63 current_thread_info()->addr_limit = fs; 64 } 65 66 #define segment_eq(a,b) ((a) == (b)) 67 68 /* 69 * Return 1 if addr < current->addr_limit, 0 otherwise. 70 */ 71 #define __addr_ok(addr) \ 72 ({ \ 73 unsigned long flag; \ 74 asm("cmp %1, %0; cset %0, lo" \ 75 : "=&r" (flag) \ 76 : "r" (addr), "0" (current_thread_info()->addr_limit) \ 77 : "cc"); \ 78 flag; \ 79 }) 80 81 /* 82 * Test whether a block of memory is a valid user space address. 83 * Returns 1 if the range is valid, 0 otherwise. 84 * 85 * This is equivalent to the following test: 86 * (u65)addr + (u65)size < (u65)current->addr_limit 87 * 88 * This needs 65-bit arithmetic. 89 */ 90 #define __range_ok(addr, size) \ 91 ({ \ 92 unsigned long flag, roksum; \ 93 __chk_user_ptr(addr); \ 94 asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, cc" \ 95 : "=&r" (flag), "=&r" (roksum) \ 96 : "1" (addr), "Ir" (size), \ 97 "r" (current_thread_info()->addr_limit) \ 98 : "cc"); \ 99 flag; \ 100 }) 101 102 #define access_ok(type, addr, size) __range_ok(addr, size) 103 104 /* 105 * The "__xxx" versions of the user access functions do not verify the address 106 * space - it must have been done previously with a separate "access_ok()" 107 * call. 108 * 109 * The "__xxx_error" versions set the third argument to -EFAULT if an error 110 * occurs, and leave it unchanged on success. 111 */ 112 #define __get_user_asm(instr, reg, x, addr, err) \ 113 asm volatile( \ 114 "1: " instr " " reg "1, [%2]\n" \ 115 "2:\n" \ 116 " .section .fixup, \"ax\"\n" \ 117 " .align 2\n" \ 118 "3: mov %w0, %3\n" \ 119 " mov %1, #0\n" \ 120 " b 2b\n" \ 121 " .previous\n" \ 122 " .section __ex_table,\"a\"\n" \ 123 " .align 3\n" \ 124 " .quad 1b, 3b\n" \ 125 " .previous" \ 126 : "+r" (err), "=&r" (x) \ 127 : "r" (addr), "i" (-EFAULT)) 128 129 #define __get_user_err(x, ptr, err) \ 130 do { \ 131 unsigned long __gu_val; \ 132 __chk_user_ptr(ptr); \ 133 switch (sizeof(*(ptr))) { \ 134 case 1: \ 135 __get_user_asm("ldrb", "%w", __gu_val, (ptr), (err)); \ 136 break; \ 137 case 2: \ 138 __get_user_asm("ldrh", "%w", __gu_val, (ptr), (err)); \ 139 break; \ 140 case 4: \ 141 __get_user_asm("ldr", "%w", __gu_val, (ptr), (err)); \ 142 break; \ 143 case 8: \ 144 __get_user_asm("ldr", "%", __gu_val, (ptr), (err)); \ 145 break; \ 146 default: \ 147 BUILD_BUG(); \ 148 } \ 149 (x) = (__typeof__(*(ptr)))__gu_val; \ 150 } while (0) 151 152 #define __get_user(x, ptr) \ 153 ({ \ 154 int __gu_err = 0; \ 155 __get_user_err((x), (ptr), __gu_err); \ 156 __gu_err; \ 157 }) 158 159 #define __get_user_error(x, ptr, err) \ 160 ({ \ 161 __get_user_err((x), (ptr), (err)); \ 162 (void)0; \ 163 }) 164 165 #define __get_user_unaligned __get_user 166 167 #define get_user(x, ptr) \ 168 ({ \ 169 might_sleep(); \ 170 access_ok(VERIFY_READ, (ptr), sizeof(*(ptr))) ? \ 171 __get_user((x), (ptr)) : \ 172 ((x) = 0, -EFAULT); \ 173 }) 174 175 #define __put_user_asm(instr, reg, x, addr, err) \ 176 asm volatile( \ 177 "1: " instr " " reg "1, [%2]\n" \ 178 "2:\n" \ 179 " .section .fixup,\"ax\"\n" \ 180 " .align 2\n" \ 181 "3: mov %w0, %3\n" \ 182 " b 2b\n" \ 183 " .previous\n" \ 184 " .section __ex_table,\"a\"\n" \ 185 " .align 3\n" \ 186 " .quad 1b, 3b\n" \ 187 " .previous" \ 188 : "+r" (err) \ 189 : "r" (x), "r" (addr), "i" (-EFAULT)) 190 191 #define __put_user_err(x, ptr, err) \ 192 do { \ 193 __typeof__(*(ptr)) __pu_val = (x); \ 194 __chk_user_ptr(ptr); \ 195 switch (sizeof(*(ptr))) { \ 196 case 1: \ 197 __put_user_asm("strb", "%w", __pu_val, (ptr), (err)); \ 198 break; \ 199 case 2: \ 200 __put_user_asm("strh", "%w", __pu_val, (ptr), (err)); \ 201 break; \ 202 case 4: \ 203 __put_user_asm("str", "%w", __pu_val, (ptr), (err)); \ 204 break; \ 205 case 8: \ 206 __put_user_asm("str", "%", __pu_val, (ptr), (err)); \ 207 break; \ 208 default: \ 209 BUILD_BUG(); \ 210 } \ 211 } while (0) 212 213 #define __put_user(x, ptr) \ 214 ({ \ 215 int __pu_err = 0; \ 216 __put_user_err((x), (ptr), __pu_err); \ 217 __pu_err; \ 218 }) 219 220 #define __put_user_error(x, ptr, err) \ 221 ({ \ 222 __put_user_err((x), (ptr), (err)); \ 223 (void)0; \ 224 }) 225 226 #define __put_user_unaligned __put_user 227 228 #define put_user(x, ptr) \ 229 ({ \ 230 might_sleep(); \ 231 access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \ 232 __put_user((x), (ptr)) : \ 233 -EFAULT; \ 234 }) 235 236 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n); 237 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n); 238 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n); 239 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 240 241 extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count); 242 extern unsigned long __must_check __strnlen_user(const char __user *s, long n); 243 244 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) 245 { 246 if (access_ok(VERIFY_READ, from, n)) 247 n = __copy_from_user(to, from, n); 248 else /* security hole - plug it */ 249 memset(to, 0, n); 250 return n; 251 } 252 253 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) 254 { 255 if (access_ok(VERIFY_WRITE, to, n)) 256 n = __copy_to_user(to, from, n); 257 return n; 258 } 259 260 static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n) 261 { 262 if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n)) 263 n = __copy_in_user(to, from, n); 264 return n; 265 } 266 267 #define __copy_to_user_inatomic __copy_to_user 268 #define __copy_from_user_inatomic __copy_from_user 269 270 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 271 { 272 if (access_ok(VERIFY_WRITE, to, n)) 273 n = __clear_user(to, n); 274 return n; 275 } 276 277 static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count) 278 { 279 long res = -EFAULT; 280 if (access_ok(VERIFY_READ, src, 1)) 281 res = __strncpy_from_user(dst, src, count); 282 return res; 283 } 284 285 #define strlen_user(s) strnlen_user(s, ~0UL >> 1) 286 287 static inline long __must_check strnlen_user(const char __user *s, long n) 288 { 289 unsigned long res = 0; 290 291 if (__addr_ok(s)) 292 res = __strnlen_user(s, n); 293 294 return res; 295 } 296 297 #endif /* __ASM_UACCESS_H */ 298