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/bitops.h>
  25 #include <linux/string.h>
  26 #include <linux/thread_info.h>
  27
  28 #include <asm/alternative.h>
  29 #include <asm/cpufeature.h>
  30 #include <asm/ptrace.h>
  31 #include <asm/sysreg.h>
  32 #include <asm/errno.h>
  33 #include <asm/memory.h>
  34 #include <asm/compiler.h>
  35
  36 #define VERIFY_READ 0
  37 #define VERIFY_WRITE 1
  38
  39 /*
  40  * The exception table consists of pairs of addresses: the first is the
  41  * address of an instruction that is allowed to fault, and the second is
  42  * the address at which the program should continue.  No registers are
  43  * modified, so it is entirely up to the continuation code to figure out
  44  * what to do.
  45  *
  46  * All the routines below use bits of fixup code that are out of line
  47  * with the main instruction path.  This means when everything is well,
  48  * we don't even have to jump over them.  Further, they do not intrude
  49  * on our cache or tlb entries.
  50  */
  51
  52 struct exception_table_entry
  53 {
  54         unsigned long insn, fixup;
  55 };
  56
  57 extern int fixup_exception(struct pt_regs *regs);
  58
  59 #define KERNEL_DS       (-1UL)
  60 #define get_ds()        (KERNEL_DS)
  61
  62 #define USER_DS         TASK_SIZE_64
  63 #define get_fs()        (current_thread_info()->addr_limit)
  64
  65 static inline void set_fs(mm_segment_t fs)
  66 {
  67         current_thread_info()->addr_limit = fs;
  68 }
  69
  70 #define segment_eq(a, b)        ((a) == (b))
  71
  72 /*
  73  * Return 1 if addr < current->addr_limit, 0 otherwise.
  74  */
  75 #define __addr_ok(addr)                                                 \
  76 ({                                                                      \
  77         unsigned long flag;                                             \
  78         asm("cmp %1, %0; cset %0, lo"                                   \
  79                 : "=&r" (flag)                                          \
  80                 : "r" (addr), "0" (current_thread_info()->addr_limit)   \
  81                 : "cc");                                                \
  82         flag;                                                           \
  83 })
  84
  85 /*
  86  * Test whether a block of memory is a valid user space address.
  87  * Returns 1 if the range is valid, 0 otherwise.
  88  *
  89  * This is equivalent to the following test:
  90  * (u65)addr + (u65)size <= current->addr_limit
  91  *
  92  * This needs 65-bit arithmetic.
  93  */
  94 #define __range_ok(addr, size)                                          \
  95 ({                                                                      \
  96         unsigned long __addr = (unsigned long __force)(addr);           \
  97         unsigned long flag, roksum;                                     \
  98         __chk_user_ptr(addr);                                           \
  99         asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls"         \
 100                 : "=&r" (flag), "=&r" (roksum)                          \
 101                 : "1" (__addr), "Ir" (size),                            \
 102                   "r" (current_thread_info()->addr_limit)               \
 103                 : "cc");                                                \
 104         flag;                                                           \
 105 })
 106
 107 /*
 108  * When dealing with data aborts, watchpoints, or instruction traps we may end
 109  * up with a tagged userland pointer. Clear the tag to get a sane pointer to
 110  * pass on to access_ok(), for instance.
 111  */
 112 #define untagged_addr(addr)             sign_extend64(addr, 55)
 113
 114 #define access_ok(type, addr, size)     __range_ok(addr, size)
 115 #define user_addr_max                   get_fs
 116
 117 /*
 118  * The "__xxx" versions of the user access functions do not verify the address
 119  * space - it must have been done previously with a separate "access_ok()"
 120  * call.
 121  *
 122  * The "__xxx_error" versions set the third argument to -EFAULT if an error
 123  * occurs, and leave it unchanged on success.
 124  */
 125 #define __get_user_asm(instr, reg, x, addr, err)                        \
 126         asm volatile(                                                   \
 127         "1:     " instr "       " reg "1, [%2]\n"                       \
 128         "2:\n"                                                          \
 129         "       .section .fixup, \"ax\"\n"                              \
 130         "       .align  2\n"                                            \
 131         "3:     mov     %w0, %3\n"                                      \
 132         "       mov     %1, #0\n"                                       \
 133         "       b       2b\n"                                           \
 134         "       .previous\n"                                            \
 135         "       .section __ex_table,\"a\"\n"                            \
 136         "       .align  3\n"                                            \
 137         "       .quad   1b, 3b\n"                                       \
 138         "       .previous"                                              \
 139         : "+r" (err), "=&r" (x)                                         \
 140         : "r" (addr), "i" (-EFAULT))
 141
 142 #define __get_user_err(x, ptr, err)                                     \
 143 do {                                                                    \
 144         unsigned long __gu_val;                                         \
 145         __chk_user_ptr(ptr);                                            \
 146         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,        \
 147                         CONFIG_ARM64_PAN));                             \
 148         switch (sizeof(*(ptr))) {                                       \
 149         case 1:                                                         \
 150                 __get_user_asm("ldrb", "%w", __gu_val, (ptr), (err));   \
 151                 break;                                                  \
 152         case 2:                                                         \
 153                 __get_user_asm("ldrh", "%w", __gu_val, (ptr), (err));   \
 154                 break;                                                  \
 155         case 4:                                                         \
 156                 __get_user_asm("ldr", "%w", __gu_val, (ptr), (err));    \
 157                 break;                                                  \
 158         case 8:                                                         \
 159                 __get_user_asm("ldr", "%",  __gu_val, (ptr), (err));    \
 160                 break;                                                  \
 161         default:                                                        \
 162                 BUILD_BUG();                                            \
 163         }                                                               \
 164         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 165         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,        \
 166                         CONFIG_ARM64_PAN));                             \
 167 } while (0)
 168
 169 #define __get_user(x, ptr)                                              \
 170 ({                                                                      \
 171         int __gu_err = 0;                                               \
 172         __get_user_err((x), (ptr), __gu_err);                           \
 173         __gu_err;                                                       \
 174 })
 175
 176 #define __get_user_error(x, ptr, err)                                   \
 177 ({                                                                      \
 178         __get_user_err((x), (ptr), (err));                              \
 179         (void)0;                                                        \
 180 })
 181
 182 #define __get_user_unaligned __get_user
 183
 184 #define get_user(x, ptr)                                                \
 185 ({                                                                      \
 186         __typeof__(*(ptr)) __user *__p = (ptr);                         \
 187         might_fault();                                                  \
 188         access_ok(VERIFY_READ, __p, sizeof(*__p)) ?                     \
 189                 __get_user((x), __p) :                                  \
 190                 ((x) = 0, -EFAULT);                                     \
 191 })
 192
 193 #define __put_user_asm(instr, reg, x, addr, err)                        \
 194         asm volatile(                                                   \
 195         "1:     " instr "       " reg "1, [%2]\n"                       \
 196         "2:\n"                                                          \
 197         "       .section .fixup,\"ax\"\n"                               \
 198         "       .align  2\n"                                            \
 199         "3:     mov     %w0, %3\n"                                      \
 200         "       b       2b\n"                                           \
 201         "       .previous\n"                                            \
 202         "       .section __ex_table,\"a\"\n"                            \
 203         "       .align  3\n"                                            \
 204         "       .quad   1b, 3b\n"                                       \
 205         "       .previous"                                              \
 206         : "+r" (err)                                                    \
 207         : "r" (x), "r" (addr), "i" (-EFAULT))
 208
 209 #define __put_user_err(x, ptr, err)                                     \
 210 do {                                                                    \
 211         __typeof__(*(ptr)) __pu_val = (x);                              \
 212         __chk_user_ptr(ptr);                                            \
 213         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,        \
 214                         CONFIG_ARM64_PAN));                             \
 215         switch (sizeof(*(ptr))) {                                       \
 216         case 1:                                                         \
 217                 __put_user_asm("strb", "%w", __pu_val, (ptr), (err));   \
 218                 break;                                                  \
 219         case 2:                                                         \
 220                 __put_user_asm("strh", "%w", __pu_val, (ptr), (err));   \
 221                 break;                                                  \
 222         case 4:                                                         \
 223                 __put_user_asm("str",  "%w", __pu_val, (ptr), (err));   \
 224                 break;                                                  \
 225         case 8:                                                         \
 226                 __put_user_asm("str",  "%", __pu_val, (ptr), (err));    \
 227                 break;                                                  \
 228         default:                                                        \
 229                 BUILD_BUG();                                            \
 230         }                                                               \
 231         asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,        \
 232                         CONFIG_ARM64_PAN));                             \
 233 } while (0)
 234
 235 #define __put_user(x, ptr)                                              \
 236 ({                                                                      \
 237         int __pu_err = 0;                                               \
 238         __put_user_err((x), (ptr), __pu_err);                           \
 239         __pu_err;                                                       \
 240 })
 241
 242 #define __put_user_error(x, ptr, err)                                   \
 243 ({                                                                      \
 244         __put_user_err((x), (ptr), (err));                              \
 245         (void)0;                                                        \
 246 })
 247
 248 #define __put_user_unaligned __put_user
 249
 250 #define put_user(x, ptr)                                                \
 251 ({                                                                      \
 252         __typeof__(*(ptr)) __user *__p = (ptr);                         \
 253         might_fault();                                                  \
 254         access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ?                    \
 255                 __put_user((x), __p) :                                  \
 256                 -EFAULT;                                                \
 257 })
 258
 259 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 260 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 261 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
 262 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 263
 264 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 265 {
 266         if (access_ok(VERIFY_READ, from, n))
 267                 n = __copy_from_user(to, from, n);
 268         else /* security hole - plug it */
 269                 memset(to, 0, n);
 270         return n;
 271 }
 272
 273 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 274 {
 275         if (access_ok(VERIFY_WRITE, to, n))
 276                 n = __copy_to_user(to, from, n);
 277         return n;
 278 }
 279
 280 static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n)
 281 {
 282         if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n))
 283                 n = __copy_in_user(to, from, n);
 284         return n;
 285 }
 286
 287 #define __copy_to_user_inatomic __copy_to_user
 288 #define __copy_from_user_inatomic __copy_from_user
 289
 290 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 291 {
 292         if (access_ok(VERIFY_WRITE, to, n))
 293                 n = __clear_user(to, n);
 294         return n;
 295 }
 296
 297 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 298
 299 extern __must_check long strlen_user(const char __user *str);
 300 extern __must_check long strnlen_user(const char __user *str, long n);
 301
 302 #endif /* __ASM_UACCESS_H */