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/alternative.h>
  28 #include <asm/cpufeature.h>
  29 #include <asm/ptrace.h>
  30 #include <asm/sysreg.h>
  31 #include <asm/errno.h>
  32 #include <asm/memory.h>
  33 #include <asm/compiler.h>
  34
  35 #define VERIFY_READ 0
  36 #define VERIFY_WRITE 1
  37
  38 /*
  39  * The exception table consists of pairs of addresses: the first is the
  40  * address of an instruction that is allowed to fault, and the second is
  41  * the address at which the program should continue.  No registers are
  42  * modified, so it is entirely up to the continuation code to figure out
  43  * what to do.
  44  *
  45  * All the routines below use bits of fixup code that are out of line
  46  * with the main instruction path.  This means when everything is well,
  47  * we don't even have to jump over them.  Further, they do not intrude
  48  * on our cache or tlb entries.
  49  */
  50
  51 struct exception_table_entry
  52 {
  53         unsigned long insn, fixup;
  54 };
  55
  56 extern int fixup_exception(struct pt_regs *regs);
  57
  58 #define KERNEL_DS       (-1UL)
  59 #define get_ds()        (KERNEL_DS)
  60
  61 #define USER_DS         TASK_SIZE_64
  62 #define get_fs()        (current_thread_info()->addr_limit)
  63
  64 static inline void set_fs(mm_segment_t fs)
  65 {
  66         current_thread_info()->addr_limit = fs;
  67 }
  68
  69 #define segment_eq(a, b)        ((a) == (b))
  70
  71 /*
  72  * Return 1 if addr < current->addr_limit, 0 otherwise.
  73  */
  74 #define __addr_ok(addr)                                                 \
  75 ({                                                                      \
  76         unsigned long flag;                                             \
  77         asm("cmp %1, %0; cset %0, lo"                                   \
  78                 : "=&r" (flag)                                          \
  79                 : "r" (addr), "0" (current_thread_info()->addr_limit)   \
  80                 : "cc");                                                \
  81         flag;                                                           \
  82 })
  83
  84 /*
  85  * Test whether a block of memory is a valid user space address.
  86  * Returns 1 if the range is valid, 0 otherwise.
  87  *
  88  * This is equivalent to the following test:
  89  * (u65)addr + (u65)size <= current->addr_limit
  90  *
  91  * This needs 65-bit arithmetic.
  92  */
  93 #define __range_ok(addr, size)                                          \
  94 ({                                                                      \
  95         unsigned long flag, roksum;                                     \
  96         __chk_user_ptr(addr);                                           \
  97         asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls"         \
  98                 : "=&r" (flag), "=&r" (roksum)                          \
  99                 : "1" (addr), "Ir" (size),                              \
 100                   "r" (current_thread_info()->addr_limit)               \
 101                 : "cc");                                                \
 102         flag;                                                           \
 103 })
 104
 105 #define access_ok(type, addr, size)     __range_ok(addr, size)
 106 #define user_addr_max                   get_fs
 107
 108 /*
 109  * The "__xxx" versions of the user access functions do not verify the address
 110  * space - it must have been done previously with a separate "access_ok()"
 111  * call.
 112  *
 113  * The "__xxx_error" versions set the third argument to -EFAULT if an error
 114  * occurs, and leave it unchanged on success.
 115  */
 116 #define __get_user_asm(instr, reg, x, addr, err)                        \
 117         asm volatile(                                                   \
 118         "1:     " instr "       " reg "1, [%2]\n"                       \
 119         "2:\n"                                                          \
 120         "       .section .fixup, \"ax\"\n"                              \
 121         "       .align  2\n"                                            \
 122         "3:     mov     %w0, %3\n"                                      \
 123         "       mov     %1, #0\n"                                       \
 124         "       b       2b\n"                                           \
 125         "       .previous\n"                                            \
 126         "       .section __ex_table,\"a\"\n"                            \
 127         "       .align  3\n"                                            \
 128         "       .quad   1b, 3b\n"                                       \
 129         "       .previous"                                              \
 130         : "+r" (err), "=&r" (x)                                         \
 131         : "r" (addr), "i" (-EFAULT))
 132
 133 #define __get_user_err(x, ptr, err)                                     \
 134 do {                                                                    \
 135         unsigned long __gu_val;                                         \
 136         __chk_user_ptr(ptr);                                            \
 137         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,        \
 138                         CONFIG_ARM64_PAN));                             \
 139         switch (sizeof(*(ptr))) {                                       \
 140         case 1:                                                         \
 141                 __get_user_asm("ldrb", "%w", __gu_val, (ptr), (err));   \
 142                 break;                                                  \
 143         case 2:                                                         \
 144                 __get_user_asm("ldrh", "%w", __gu_val, (ptr), (err));   \
 145                 break;                                                  \
 146         case 4:                                                         \
 147                 __get_user_asm("ldr", "%w", __gu_val, (ptr), (err));    \
 148                 break;                                                  \
 149         case 8:                                                         \
 150                 __get_user_asm("ldr", "%",  __gu_val, (ptr), (err));    \
 151                 break;                                                  \
 152         default:                                                        \
 153                 BUILD_BUG();                                            \
 154         }                                                               \
 155         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 156         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,        \
 157                         CONFIG_ARM64_PAN));                             \
 158 } while (0)
 159
 160 #define __get_user(x, ptr)                                              \
 161 ({                                                                      \
 162         int __gu_err = 0;                                               \
 163         __get_user_err((x), (ptr), __gu_err);                           \
 164         __gu_err;                                                       \
 165 })
 166
 167 #define __get_user_error(x, ptr, err)                                   \
 168 ({                                                                      \
 169         __get_user_err((x), (ptr), (err));                              \
 170         (void)0;                                                        \
 171 })
 172
 173 #define __get_user_unaligned __get_user
 174
 175 #define get_user(x, ptr)                                                \
 176 ({                                                                      \
 177         __typeof__(*(ptr)) __user *__p = (ptr);                         \
 178         might_fault();                                                  \
 179         access_ok(VERIFY_READ, __p, sizeof(*__p)) ?                     \
 180                 __get_user((x), __p) :                                  \
 181                 ((x) = 0, -EFAULT);                                     \
 182 })
 183
 184 #define __put_user_asm(instr, reg, x, addr, err)                        \
 185         asm volatile(                                                   \
 186         "1:     " instr "       " reg "1, [%2]\n"                       \
 187         "2:\n"                                                          \
 188         "       .section .fixup,\"ax\"\n"                               \
 189         "       .align  2\n"                                            \
 190         "3:     mov     %w0, %3\n"                                      \
 191         "       b       2b\n"                                           \
 192         "       .previous\n"                                            \
 193         "       .section __ex_table,\"a\"\n"                            \
 194         "       .align  3\n"                                            \
 195         "       .quad   1b, 3b\n"                                       \
 196         "       .previous"                                              \
 197         : "+r" (err)                                                    \
 198         : "r" (x), "r" (addr), "i" (-EFAULT))
 199
 200 #define __put_user_err(x, ptr, err)                                     \
 201 do {                                                                    \
 202         __typeof__(*(ptr)) __pu_val = (x);                              \
 203         __chk_user_ptr(ptr);                                            \
 204         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,        \
 205                         CONFIG_ARM64_PAN));                             \
 206         switch (sizeof(*(ptr))) {                                       \
 207         case 1:                                                         \
 208                 __put_user_asm("strb", "%w", __pu_val, (ptr), (err));   \
 209                 break;                                                  \
 210         case 2:                                                         \
 211                 __put_user_asm("strh", "%w", __pu_val, (ptr), (err));   \
 212                 break;                                                  \
 213         case 4:                                                         \
 214                 __put_user_asm("str",  "%w", __pu_val, (ptr), (err));   \
 215                 break;                                                  \
 216         case 8:                                                         \
 217                 __put_user_asm("str",  "%", __pu_val, (ptr), (err));    \
 218                 break;                                                  \
 219         default:                                                        \
 220                 BUILD_BUG();                                            \
 221         }                                                               \
 222         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,        \
 223                         CONFIG_ARM64_PAN));                             \
 224 } while (0)
 225
 226 #define __put_user(x, ptr)                                              \
 227 ({                                                                      \
 228         int __pu_err = 0;                                               \
 229         __put_user_err((x), (ptr), __pu_err);                           \
 230         __pu_err;                                                       \
 231 })
 232
 233 #define __put_user_error(x, ptr, err)                                   \
 234 ({                                                                      \
 235         __put_user_err((x), (ptr), (err));                              \
 236         (void)0;                                                        \
 237 })
 238
 239 #define __put_user_unaligned __put_user
 240
 241 #define put_user(x, ptr)                                                \
 242 ({                                                                      \
 243         __typeof__(*(ptr)) __user *__p = (ptr);                         \
 244         might_fault();                                                  \
 245         access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ?                    \
 246                 __put_user((x), __p) :                                  \
 247                 -EFAULT;                                                \
 248 })
 249
 250 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 251 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 252 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
 253 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 254
 255 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 256 {
 257         if (access_ok(VERIFY_READ, from, n))
 258                 n = __copy_from_user(to, from, n);
 259         else /* security hole - plug it */
 260                 memset(to, 0, n);
 261         return n;
 262 }
 263
 264 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 265 {
 266         if (access_ok(VERIFY_WRITE, to, n))
 267                 n = __copy_to_user(to, from, n);
 268         return n;
 269 }
 270
 271 static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n)
 272 {
 273         if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n))
 274                 n = __copy_in_user(to, from, n);
 275         return n;
 276 }
 277
 278 #define __copy_to_user_inatomic __copy_to_user
 279 #define __copy_from_user_inatomic __copy_from_user
 280
 281 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 282 {
 283         if (access_ok(VERIFY_WRITE, to, n))
 284                 n = __clear_user(to, n);
 285         return n;
 286 }
 287
 288 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 289
 290 extern __must_check long strlen_user(const char __user *str);
 291 extern __must_check long strnlen_user(const char __user *str, long n);
 292
 293 #endif /* __ASM_UACCESS_H */