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 <= 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, ls" \ 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 #define user_addr_max get_fs 104 105 /* 106 * The "__xxx" versions of the user access functions do not verify the address 107 * space - it must have been done previously with a separate "access_ok()" 108 * call. 109 * 110 * The "__xxx_error" versions set the third argument to -EFAULT if an error 111 * occurs, and leave it unchanged on success. 112 */ 113 #define __get_user_asm(instr, reg, x, addr, err) \ 114 asm volatile( \ 115 "1: " instr " " reg "1, [%2]\n" \ 116 "2:\n" \ 117 " .section .fixup, \"ax\"\n" \ 118 " .align 2\n" \ 119 "3: mov %w0, %3\n" \ 120 " mov %1, #0\n" \ 121 " b 2b\n" \ 122 " .previous\n" \ 123 " .section __ex_table,\"a\"\n" \ 124 " .align 3\n" \ 125 " .quad 1b, 3b\n" \ 126 " .previous" \ 127 : "+r" (err), "=&r" (x) \ 128 : "r" (addr), "i" (-EFAULT)) 129 130 #define __get_user_err(x, ptr, err) \ 131 do { \ 132 unsigned long __gu_val; \ 133 __chk_user_ptr(ptr); \ 134 switch (sizeof(*(ptr))) { \ 135 case 1: \ 136 __get_user_asm("ldrb", "%w", __gu_val, (ptr), (err)); \ 137 break; \ 138 case 2: \ 139 __get_user_asm("ldrh", "%w", __gu_val, (ptr), (err)); \ 140 break; \ 141 case 4: \ 142 __get_user_asm("ldr", "%w", __gu_val, (ptr), (err)); \ 143 break; \ 144 case 8: \ 145 __get_user_asm("ldr", "%", __gu_val, (ptr), (err)); \ 146 break; \ 147 default: \ 148 BUILD_BUG(); \ 149 } \ 150 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 151 } while (0) 152 153 #define __get_user(x, ptr) \ 154 ({ \ 155 int __gu_err = 0; \ 156 __get_user_err((x), (ptr), __gu_err); \ 157 __gu_err; \ 158 }) 159 160 #define __get_user_error(x, ptr, err) \ 161 ({ \ 162 __get_user_err((x), (ptr), (err)); \ 163 (void)0; \ 164 }) 165 166 #define __get_user_unaligned __get_user 167 168 #define get_user(x, ptr) \ 169 ({ \ 170 __typeof__(*(ptr)) __user *__p = (ptr); \ 171 might_fault(); \ 172 access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ 173 __get_user((x), __p) : \ 174 ((x) = 0, -EFAULT); \ 175 }) 176 177 #define __put_user_asm(instr, reg, x, addr, err) \ 178 asm volatile( \ 179 "1: " instr " " reg "1, [%2]\n" \ 180 "2:\n" \ 181 " .section .fixup,\"ax\"\n" \ 182 " .align 2\n" \ 183 "3: mov %w0, %3\n" \ 184 " b 2b\n" \ 185 " .previous\n" \ 186 " .section __ex_table,\"a\"\n" \ 187 " .align 3\n" \ 188 " .quad 1b, 3b\n" \ 189 " .previous" \ 190 : "+r" (err) \ 191 : "r" (x), "r" (addr), "i" (-EFAULT)) 192 193 #define __put_user_err(x, ptr, err) \ 194 do { \ 195 __typeof__(*(ptr)) __pu_val = (x); \ 196 __chk_user_ptr(ptr); \ 197 switch (sizeof(*(ptr))) { \ 198 case 1: \ 199 __put_user_asm("strb", "%w", __pu_val, (ptr), (err)); \ 200 break; \ 201 case 2: \ 202 __put_user_asm("strh", "%w", __pu_val, (ptr), (err)); \ 203 break; \ 204 case 4: \ 205 __put_user_asm("str", "%w", __pu_val, (ptr), (err)); \ 206 break; \ 207 case 8: \ 208 __put_user_asm("str", "%", __pu_val, (ptr), (err)); \ 209 break; \ 210 default: \ 211 BUILD_BUG(); \ 212 } \ 213 } while (0) 214 215 #define __put_user(x, ptr) \ 216 ({ \ 217 int __pu_err = 0; \ 218 __put_user_err((x), (ptr), __pu_err); \ 219 __pu_err; \ 220 }) 221 222 #define __put_user_error(x, ptr, err) \ 223 ({ \ 224 __put_user_err((x), (ptr), (err)); \ 225 (void)0; \ 226 }) 227 228 #define __put_user_unaligned __put_user 229 230 #define put_user(x, ptr) \ 231 ({ \ 232 __typeof__(*(ptr)) __user *__p = (ptr); \ 233 might_fault(); \ 234 access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ 235 __put_user((x), __p) : \ 236 -EFAULT; \ 237 }) 238 239 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n); 240 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n); 241 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n); 242 extern unsigned long __must_check __clear_user(void __user *addr, unsigned 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 extern long strncpy_from_user(char *dest, const char __user *src, long count); 278 279 extern __must_check long strlen_user(const char __user *str); 280 extern __must_check long strnlen_user(const char __user *str, long n); 281 282 #endif /* __ASM_UACCESS_H */ 283