kernel/arch/arm64/include/asm/uaccess.h

   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 */