arch/riscv/include/asm/uaccess.h

   1 /*
   2  * Copyright (C) 2012 Regents of the University of California
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful,
   9  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  *   GNU General Public License for more details.
  12  *
  13  * This file was copied from include/asm-generic/uaccess.h
  14  */
  15
  16 #ifndef _ASM_RISCV_UACCESS_H
  17 #define _ASM_RISCV_UACCESS_H
  18
  19 /*
  20  * User space memory access functions
  21  */
  22 #include <linux/errno.h>
  23 #include <linux/compiler.h>
  24 #include <linux/thread_info.h>
  25 #include <asm/byteorder.h>
  26 #include <asm/asm.h>
  27
  28 #define __enable_user_access()                                                  \
  29         __asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory")
  30 #define __disable_user_access()                                                 \
  31         __asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")
  32
  33 /*
  34  * The fs value determines whether argument validity checking should be
  35  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  36  * get_fs() == KERNEL_DS, checking is bypassed.
  37  *
  38  * For historical reasons, these macros are grossly misnamed.
  39  */
  40
  41 #define KERNEL_DS       (~0UL)
  42 #define USER_DS         (TASK_SIZE)
  43
  44 #define get_ds()        (KERNEL_DS)
  45 #define get_fs()        (current_thread_info()->addr_limit)
  46
  47 static inline void set_fs(mm_segment_t fs)
  48 {
  49         current_thread_info()->addr_limit = fs;
  50 }
  51
  52 #define segment_eq(a, b) ((a) == (b))
  53
  54 #define user_addr_max() (get_fs())
  55
  56
  57 /**
  58  * access_ok: - Checks if a user space pointer is valid
  59  * @addr: User space pointer to start of block to check
  60  * @size: Size of block to check
  61  *
  62  * Context: User context only.  This function may sleep.
  63  *
  64  * Checks if a pointer to a block of memory in user space is valid.
  65  *
  66  * Returns true (nonzero) if the memory block may be valid, false (zero)
  67  * if it is definitely invalid.
  68  *
  69  * Note that, depending on architecture, this function probably just
  70  * checks that the pointer is in the user space range - after calling
  71  * this function, memory access functions may still return -EFAULT.
  72  */
  73 #define access_ok(addr, size) ({                                        \
  74         __chk_user_ptr(addr);                                           \
  75         likely(__access_ok((unsigned long __force)(addr), (size)));     \
  76 })
  77
  78 /*
  79  * Ensure that the range [addr, addr+size) is within the process's
  80  * address space
  81  */
  82 static inline int __access_ok(unsigned long addr, unsigned long size)
  83 {
  84         const mm_segment_t fs = get_fs();
  85
  86         return (size <= fs) && (addr <= (fs - size));
  87 }
  88
  89 /*
  90  * The exception table consists of pairs of addresses: the first is the
  91  * address of an instruction that is allowed to fault, and the second is
  92  * the address at which the program should continue.  No registers are
  93  * modified, so it is entirely up to the continuation code to figure out
  94  * what to do.
  95  *
  96  * All the routines below use bits of fixup code that are out of line
  97  * with the main instruction path.  This means when everything is well,
  98  * we don't even have to jump over them.  Further, they do not intrude
  99  * on our cache or tlb entries.
 100  */
 101
 102 struct exception_table_entry {
 103         unsigned long insn, fixup;
 104 };
 105
 106 extern int fixup_exception(struct pt_regs *state);
 107
 108 #if defined(__LITTLE_ENDIAN)
 109 #define __MSW   1
 110 #define __LSW   0
 111 #elif defined(__BIG_ENDIAN)
 112 #define __MSW   0
 113 #define __LSW   1
 114 #else
 115 #error "Unknown endianness"
 116 #endif
 117
 118 /*
 119  * The "__xxx" versions of the user access functions do not verify the address
 120  * space - it must have been done previously with a separate "access_ok()"
 121  * call.
 122  */
 123
 124 #define __get_user_asm(insn, x, ptr, err)                       \
 125 do {                                                            \
 126         uintptr_t __tmp;                                        \
 127         __typeof__(x) __x;                                      \
 128         __enable_user_access();                                 \
 129         __asm__ __volatile__ (                                  \
 130                 "1:\n"                                          \
 131                 "       " insn " %1, %3\n"                      \
 132                 "2:\n"                                          \
 133                 "       .section .fixup,\"ax\"\n"               \
 134                 "       .balign 4\n"                            \
 135                 "3:\n"                                          \
 136                 "       li %0, %4\n"                            \
 137                 "       li %1, 0\n"                             \
 138                 "       jump 2b, %2\n"                          \
 139                 "       .previous\n"                            \
 140                 "       .section __ex_table,\"a\"\n"            \
 141                 "       .balign " RISCV_SZPTR "\n"                      \
 142                 "       " RISCV_PTR " 1b, 3b\n"                 \
 143                 "       .previous"                              \
 144                 : "+r" (err), "=&r" (__x), "=r" (__tmp)         \
 145                 : "m" (*(ptr)), "i" (-EFAULT));                 \
 146         __disable_user_access();                                \
 147         (x) = __x;                                              \
 148 } while (0)
 149
 150 #ifdef CONFIG_64BIT
 151 #define __get_user_8(x, ptr, err) \
 152         __get_user_asm("ld", x, ptr, err)
 153 #else /* !CONFIG_64BIT */
 154 #define __get_user_8(x, ptr, err)                               \
 155 do {                                                            \
 156         u32 __user *__ptr = (u32 __user *)(ptr);                \
 157         u32 __lo, __hi;                                         \
 158         uintptr_t __tmp;                                        \
 159         __enable_user_access();                                 \
 160         __asm__ __volatile__ (                                  \
 161                 "1:\n"                                          \
 162                 "       lw %1, %4\n"                            \
 163                 "2:\n"                                          \
 164                 "       lw %2, %5\n"                            \
 165                 "3:\n"                                          \
 166                 "       .section .fixup,\"ax\"\n"               \
 167                 "       .balign 4\n"                            \
 168                 "4:\n"                                          \
 169                 "       li %0, %6\n"                            \
 170                 "       li %1, 0\n"                             \
 171                 "       li %2, 0\n"                             \
 172                 "       jump 3b, %3\n"                          \
 173                 "       .previous\n"                            \
 174                 "       .section __ex_table,\"a\"\n"            \
 175                 "       .balign " RISCV_SZPTR "\n"                      \
 176                 "       " RISCV_PTR " 1b, 4b\n"                 \
 177                 "       " RISCV_PTR " 2b, 4b\n"                 \
 178                 "       .previous"                              \
 179                 : "+r" (err), "=&r" (__lo), "=r" (__hi),        \
 180                         "=r" (__tmp)                            \
 181                 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]),       \
 182                         "i" (-EFAULT));                         \
 183         __disable_user_access();                                \
 184         (x) = (__typeof__(x))((__typeof__((x)-(x)))(            \
 185                 (((u64)__hi << 32) | __lo)));                   \
 186 } while (0)
 187 #endif /* CONFIG_64BIT */
 188
 189
 190 /**
 191  * __get_user: - Get a simple variable from user space, with less checking.
 192  * @x:   Variable to store result.
 193  * @ptr: Source address, in user space.
 194  *
 195  * Context: User context only.  This function may sleep.
 196  *
 197  * This macro copies a single simple variable from user space to kernel
 198  * space.  It supports simple types like char and int, but not larger
 199  * data types like structures or arrays.
 200  *
 201  * @ptr must have pointer-to-simple-variable type, and the result of
 202  * dereferencing @ptr must be assignable to @x without a cast.
 203  *
 204  * Caller must check the pointer with access_ok() before calling this
 205  * function.
 206  *
 207  * Returns zero on success, or -EFAULT on error.
 208  * On error, the variable @x is set to zero.
 209  */
 210 #define __get_user(x, ptr)                                      \
 211 ({                                                              \
 212         register long __gu_err = 0;                             \
 213         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);      \
 214         __chk_user_ptr(__gu_ptr);                               \
 215         switch (sizeof(*__gu_ptr)) {                            \
 216         case 1:                                                 \
 217                 __get_user_asm("lb", (x), __gu_ptr, __gu_err);  \
 218                 break;                                          \
 219         case 2:                                                 \
 220                 __get_user_asm("lh", (x), __gu_ptr, __gu_err);  \
 221                 break;                                          \
 222         case 4:                                                 \
 223                 __get_user_asm("lw", (x), __gu_ptr, __gu_err);  \
 224                 break;                                          \
 225         case 8:                                                 \
 226                 __get_user_8((x), __gu_ptr, __gu_err);  \
 227                 break;                                          \
 228         default:                                                \
 229                 BUILD_BUG();                                    \
 230         }                                                       \
 231         __gu_err;                                               \
 232 })
 233
 234 /**
 235  * get_user: - Get a simple variable from user space.
 236  * @x:   Variable to store result.
 237  * @ptr: Source address, in user space.
 238  *
 239  * Context: User context only.  This function may sleep.
 240  *
 241  * This macro copies a single simple variable from user space to kernel
 242  * space.  It supports simple types like char and int, but not larger
 243  * data types like structures or arrays.
 244  *
 245  * @ptr must have pointer-to-simple-variable type, and the result of
 246  * dereferencing @ptr must be assignable to @x without a cast.
 247  *
 248  * Returns zero on success, or -EFAULT on error.
 249  * On error, the variable @x is set to zero.
 250  */
 251 #define get_user(x, ptr)                                        \
 252 ({                                                              \
 253         const __typeof__(*(ptr)) __user *__p = (ptr);           \
 254         might_fault();                                          \
 255         access_ok(__p, sizeof(*__p)) ?          \
 256                 __get_user((x), __p) :                          \
 257                 ((x) = 0, -EFAULT);                             \
 258 })
 259
 260 #define __put_user_asm(insn, x, ptr, err)                       \
 261 do {                                                            \
 262         uintptr_t __tmp;                                        \
 263         __typeof__(*(ptr)) __x = x;                             \
 264         __enable_user_access();                                 \
 265         __asm__ __volatile__ (                                  \
 266                 "1:\n"                                          \
 267                 "       " insn " %z3, %2\n"                     \
 268                 "2:\n"                                          \
 269                 "       .section .fixup,\"ax\"\n"               \
 270                 "       .balign 4\n"                            \
 271                 "3:\n"                                          \
 272                 "       li %0, %4\n"                            \
 273                 "       jump 2b, %1\n"                          \
 274                 "       .previous\n"                            \
 275                 "       .section __ex_table,\"a\"\n"            \
 276                 "       .balign " RISCV_SZPTR "\n"                      \
 277                 "       " RISCV_PTR " 1b, 3b\n"                 \
 278                 "       .previous"                              \
 279                 : "+r" (err), "=r" (__tmp), "=m" (*(ptr))       \
 280                 : "rJ" (__x), "i" (-EFAULT));                   \
 281         __disable_user_access();                                \
 282 } while (0)
 283
 284 #ifdef CONFIG_64BIT
 285 #define __put_user_8(x, ptr, err) \
 286         __put_user_asm("sd", x, ptr, err)
 287 #else /* !CONFIG_64BIT */
 288 #define __put_user_8(x, ptr, err)                               \
 289 do {                                                            \
 290         u32 __user *__ptr = (u32 __user *)(ptr);                \
 291         u64 __x = (__typeof__((x)-(x)))(x);                     \
 292         uintptr_t __tmp;                                        \
 293         __enable_user_access();                                 \
 294         __asm__ __volatile__ (                                  \
 295                 "1:\n"                                          \
 296                 "       sw %z4, %2\n"                           \
 297                 "2:\n"                                          \
 298                 "       sw %z5, %3\n"                           \
 299                 "3:\n"                                          \
 300                 "       .section .fixup,\"ax\"\n"               \
 301                 "       .balign 4\n"                            \
 302                 "4:\n"                                          \
 303                 "       li %0, %6\n"                            \
 304                 "       jump 2b, %1\n"                          \
 305                 "       .previous\n"                            \
 306                 "       .section __ex_table,\"a\"\n"            \
 307                 "       .balign " RISCV_SZPTR "\n"                      \
 308                 "       " RISCV_PTR " 1b, 4b\n"                 \
 309                 "       " RISCV_PTR " 2b, 4b\n"                 \
 310                 "       .previous"                              \
 311                 : "+r" (err), "=r" (__tmp),                     \
 312                         "=m" (__ptr[__LSW]),                    \
 313                         "=m" (__ptr[__MSW])                     \
 314                 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \
 315         __disable_user_access();                                \
 316 } while (0)
 317 #endif /* CONFIG_64BIT */
 318
 319
 320 /**
 321  * __put_user: - Write a simple value into user space, with less checking.
 322  * @x:   Value to copy to user space.
 323  * @ptr: Destination address, in user space.
 324  *
 325  * Context: User context only.  This function may sleep.
 326  *
 327  * This macro copies a single simple value from kernel space to user
 328  * space.  It supports simple types like char and int, but not larger
 329  * data types like structures or arrays.
 330  *
 331  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 332  * to the result of dereferencing @ptr.
 333  *
 334  * Caller must check the pointer with access_ok() before calling this
 335  * function.
 336  *
 337  * Returns zero on success, or -EFAULT on error.
 338  */
 339 #define __put_user(x, ptr)                                      \
 340 ({                                                              \
 341         register long __pu_err = 0;                             \
 342         __typeof__(*(ptr)) __user *__gu_ptr = (ptr);            \
 343         __chk_user_ptr(__gu_ptr);                               \
 344         switch (sizeof(*__gu_ptr)) {                            \
 345         case 1:                                                 \
 346                 __put_user_asm("sb", (x), __gu_ptr, __pu_err);  \
 347                 break;                                          \
 348         case 2:                                                 \
 349                 __put_user_asm("sh", (x), __gu_ptr, __pu_err);  \
 350                 break;                                          \
 351         case 4:                                                 \
 352                 __put_user_asm("sw", (x), __gu_ptr, __pu_err);  \
 353                 break;                                          \
 354         case 8:                                                 \
 355                 __put_user_8((x), __gu_ptr, __pu_err);  \
 356                 break;                                          \
 357         default:                                                \
 358                 BUILD_BUG();                                    \
 359         }                                                       \
 360         __pu_err;                                               \
 361 })
 362
 363 /**
 364  * put_user: - Write a simple value into user space.
 365  * @x:   Value to copy to user space.
 366  * @ptr: Destination address, in user space.
 367  *
 368  * Context: User context only.  This function may sleep.
 369  *
 370  * This macro copies a single simple value from kernel space to user
 371  * space.  It supports simple types like char and int, but not larger
 372  * data types like structures or arrays.
 373  *
 374  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 375  * to the result of dereferencing @ptr.
 376  *
 377  * Returns zero on success, or -EFAULT on error.
 378  */
 379 #define put_user(x, ptr)                                        \
 380 ({                                                              \
 381         __typeof__(*(ptr)) __user *__p = (ptr);                 \
 382         might_fault();                                          \
 383         access_ok(__p, sizeof(*__p)) ?          \
 384                 __put_user((x), __p) :                          \
 385                 -EFAULT;                                        \
 386 })
 387
 388
 389 extern unsigned long __must_check __asm_copy_to_user(void __user *to,
 390         const void *from, unsigned long n);
 391 extern unsigned long __must_check __asm_copy_from_user(void *to,
 392         const void __user *from, unsigned long n);
 393
 394 static inline unsigned long
 395 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 396 {
 397         return __asm_copy_from_user(to, from, n);
 398 }
 399
 400 static inline unsigned long
 401 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 402 {
 403         return __asm_copy_to_user(to, from, n);
 404 }
 405
 406 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 407
 408 extern long __must_check strlen_user(const char __user *str);
 409 extern long __must_check strnlen_user(const char __user *str, long n);
 410
 411 extern
 412 unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 413
 414 static inline
 415 unsigned long __must_check clear_user(void __user *to, unsigned long n)
 416 {
 417         might_fault();
 418         return access_ok(to, n) ?
 419                 __clear_user(to, n) : n;
 420 }
 421
 422 /*
 423  * Atomic compare-and-exchange, but with a fixup for userspace faults.  Faults
 424  * will set "err" to -EFAULT, while successful accesses return the previous
 425  * value.
 426  */
 427 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb)      \
 428 ({                                                              \
 429         __typeof__(ptr) __ptr = (ptr);                          \
 430         __typeof__(*(ptr)) __old = (old);                       \
 431         __typeof__(*(ptr)) __new = (new);                       \
 432         __typeof__(*(ptr)) __ret;                               \
 433         __typeof__(err) __err = 0;                              \
 434         register unsigned int __rc;                             \
 435         __enable_user_access();                                 \
 436         switch (size) {                                         \
 437         case 4:                                                 \
 438                 __asm__ __volatile__ (                          \
 439                 "0:\n"                                          \
 440                 "       lr.w" #scb " %[ret], %[ptr]\n"          \
 441                 "       bne          %[ret], %z[old], 1f\n"     \
 442                 "       sc.w" #lrb " %[rc], %z[new], %[ptr]\n"  \
 443                 "       bnez         %[rc], 0b\n"               \
 444                 "1:\n"                                          \
 445                 ".section .fixup,\"ax\"\n"                      \
 446                 ".balign 4\n"                                   \
 447                 "2:\n"                                          \
 448                 "       li %[err], %[efault]\n"                 \
 449                 "       jump 1b, %[rc]\n"                       \
 450                 ".previous\n"                                   \
 451                 ".section __ex_table,\"a\"\n"                   \
 452                 ".balign " RISCV_SZPTR "\n"                     \
 453                 "       " RISCV_PTR " 1b, 2b\n"                 \
 454                 ".previous\n"                                   \
 455                         : [ret] "=&r" (__ret),                  \
 456                           [rc]  "=&r" (__rc),                   \
 457                           [ptr] "+A" (*__ptr),                  \
 458                           [err] "=&r" (__err)                   \
 459                         : [old] "rJ" (__old),                   \
 460                           [new] "rJ" (__new),                   \
 461                           [efault] "i" (-EFAULT));              \
 462                 break;                                          \
 463         case 8:                                                 \
 464                 __asm__ __volatile__ (                          \
 465                 "0:\n"                                          \
 466                 "       lr.d" #scb " %[ret], %[ptr]\n"          \
 467                 "       bne          %[ret], %z[old], 1f\n"     \
 468                 "       sc.d" #lrb " %[rc], %z[new], %[ptr]\n"  \
 469                 "       bnez         %[rc], 0b\n"               \
 470                 "1:\n"                                          \
 471                 ".section .fixup,\"ax\"\n"                      \
 472                 ".balign 4\n"                                   \
 473                 "2:\n"                                          \
 474                 "       li %[err], %[efault]\n"                 \
 475                 "       jump 1b, %[rc]\n"                       \
 476                 ".previous\n"                                   \
 477                 ".section __ex_table,\"a\"\n"                   \
 478                 ".balign " RISCV_SZPTR "\n"                     \
 479                 "       " RISCV_PTR " 1b, 2b\n"                 \
 480                 ".previous\n"                                   \
 481                         : [ret] "=&r" (__ret),                  \
 482                           [rc]  "=&r" (__rc),                   \
 483                           [ptr] "+A" (*__ptr),                  \
 484                           [err] "=&r" (__err)                   \
 485                         : [old] "rJ" (__old),                   \
 486                           [new] "rJ" (__new),                   \
 487                           [efault] "i" (-EFAULT));              \
 488                 break;                                          \
 489         default:                                                \
 490                 BUILD_BUG();                                    \
 491         }                                                       \
 492         __disable_user_access();                                \
 493         (err) = __err;                                          \
 494         __ret;                                                  \
 495 })
 496
 497 #endif /* _ASM_RISCV_UACCESS_H */