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