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 KERNEL_DS       (~0UL)
  43 #define USER_DS         (TASK_SIZE)
  44
  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 #if defined(__LITTLE_ENDIAN)
 103 #define __MSW   1
 104 #define __LSW   0
 105 #elif defined(__BIG_ENDIAN)
 106 #define __MSW   0
 107 #define __LSW   1
 108 #else
 109 #error "Unknown endianness"
 110 #endif
 111
 112 /*
 113  * The "__xxx" versions of the user access functions do not verify the address
 114  * space - it must have been done previously with a separate "access_ok()"
 115  * call.
 116  */
 117
 118 #define __get_user_asm(insn, x, ptr, err)                       \
 119 do {                                                            \
 120         uintptr_t __tmp;                                        \
 121         __typeof__(x) __x;                                      \
 122         __enable_user_access();                                 \
 123         __asm__ __volatile__ (                                  \
 124                 "1:\n"                                          \
 125                 "       " insn " %1, %3\n"                      \
 126                 "2:\n"                                          \
 127                 "       .section .fixup,\"ax\"\n"               \
 128                 "       .balign 4\n"                            \
 129                 "3:\n"                                          \
 130                 "       li %0, %4\n"                            \
 131                 "       li %1, 0\n"                             \
 132                 "       jump 2b, %2\n"                          \
 133                 "       .previous\n"                            \
 134                 "       .section __ex_table,\"a\"\n"            \
 135                 "       .balign " RISCV_SZPTR "\n"                      \
 136                 "       " RISCV_PTR " 1b, 3b\n"                 \
 137                 "       .previous"                              \
 138                 : "+r" (err), "=&r" (__x), "=r" (__tmp)         \
 139                 : "m" (*(ptr)), "i" (-EFAULT));                 \
 140         __disable_user_access();                                \
 141         (x) = __x;                                              \
 142 } while (0)
 143
 144 #ifdef CONFIG_64BIT
 145 #define __get_user_8(x, ptr, err) \
 146         __get_user_asm("ld", x, ptr, err)
 147 #else /* !CONFIG_64BIT */
 148 #define __get_user_8(x, ptr, err)                               \
 149 do {                                                            \
 150         u32 __user *__ptr = (u32 __user *)(ptr);                \
 151         u32 __lo, __hi;                                         \
 152         uintptr_t __tmp;                                        \
 153         __enable_user_access();                                 \
 154         __asm__ __volatile__ (                                  \
 155                 "1:\n"                                          \
 156                 "       lw %1, %4\n"                            \
 157                 "2:\n"                                          \
 158                 "       lw %2, %5\n"                            \
 159                 "3:\n"                                          \
 160                 "       .section .fixup,\"ax\"\n"               \
 161                 "       .balign 4\n"                            \
 162                 "4:\n"                                          \
 163                 "       li %0, %6\n"                            \
 164                 "       li %1, 0\n"                             \
 165                 "       li %2, 0\n"                             \
 166                 "       jump 3b, %3\n"                          \
 167                 "       .previous\n"                            \
 168                 "       .section __ex_table,\"a\"\n"            \
 169                 "       .balign " RISCV_SZPTR "\n"                      \
 170                 "       " RISCV_PTR " 1b, 4b\n"                 \
 171                 "       " RISCV_PTR " 2b, 4b\n"                 \
 172                 "       .previous"                              \
 173                 : "+r" (err), "=&r" (__lo), "=r" (__hi),        \
 174                         "=r" (__tmp)                            \
 175                 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]),       \
 176                         "i" (-EFAULT));                         \
 177         __disable_user_access();                                \
 178         (x) = (__typeof__(x))((__typeof__((x)-(x)))(            \
 179                 (((u64)__hi << 32) | __lo)));                   \
 180 } while (0)
 181 #endif /* CONFIG_64BIT */
 182
 183
 184 /**
 185  * __get_user: - Get a simple variable from user space, with less checking.
 186  * @x:   Variable to store result.
 187  * @ptr: Source address, in user space.
 188  *
 189  * Context: User context only.  This function may sleep.
 190  *
 191  * This macro copies a single simple variable from user space to kernel
 192  * space.  It supports simple types like char and int, but not larger
 193  * data types like structures or arrays.
 194  *
 195  * @ptr must have pointer-to-simple-variable type, and the result of
 196  * dereferencing @ptr must be assignable to @x without a cast.
 197  *
 198  * Caller must check the pointer with access_ok() before calling this
 199  * function.
 200  *
 201  * Returns zero on success, or -EFAULT on error.
 202  * On error, the variable @x is set to zero.
 203  */
 204 #define __get_user(x, ptr)                                      \
 205 ({                                                              \
 206         register long __gu_err = 0;                             \
 207         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);      \
 208         __chk_user_ptr(__gu_ptr);                               \
 209         switch (sizeof(*__gu_ptr)) {                            \
 210         case 1:                                                 \
 211                 __get_user_asm("lb", (x), __gu_ptr, __gu_err);  \
 212                 break;                                          \
 213         case 2:                                                 \
 214                 __get_user_asm("lh", (x), __gu_ptr, __gu_err);  \
 215                 break;                                          \
 216         case 4:                                                 \
 217                 __get_user_asm("lw", (x), __gu_ptr, __gu_err);  \
 218                 break;                                          \
 219         case 8:                                                 \
 220                 __get_user_8((x), __gu_ptr, __gu_err);  \
 221                 break;                                          \
 222         default:                                                \
 223                 BUILD_BUG();                                    \
 224         }                                                       \
 225         __gu_err;                                               \
 226 })
 227
 228 /**
 229  * get_user: - Get a simple variable from user space.
 230  * @x:   Variable to store result.
 231  * @ptr: Source address, in user space.
 232  *
 233  * Context: User context only.  This function may sleep.
 234  *
 235  * This macro copies a single simple variable from user space to kernel
 236  * space.  It supports simple types like char and int, but not larger
 237  * data types like structures or arrays.
 238  *
 239  * @ptr must have pointer-to-simple-variable type, and the result of
 240  * dereferencing @ptr must be assignable to @x without a cast.
 241  *
 242  * Returns zero on success, or -EFAULT on error.
 243  * On error, the variable @x is set to zero.
 244  */
 245 #define get_user(x, ptr)                                        \
 246 ({                                                              \
 247         const __typeof__(*(ptr)) __user *__p = (ptr);           \
 248         might_fault();                                          \
 249         access_ok(__p, sizeof(*__p)) ?          \
 250                 __get_user((x), __p) :                          \
 251                 ((x) = 0, -EFAULT);                             \
 252 })
 253
 254 #define __put_user_asm(insn, x, ptr, err)                       \
 255 do {                                                            \
 256         uintptr_t __tmp;                                        \
 257         __typeof__(*(ptr)) __x = x;                             \
 258         __enable_user_access();                                 \
 259         __asm__ __volatile__ (                                  \
 260                 "1:\n"                                          \
 261                 "       " insn " %z3, %2\n"                     \
 262                 "2:\n"                                          \
 263                 "       .section .fixup,\"ax\"\n"               \
 264                 "       .balign 4\n"                            \
 265                 "3:\n"                                          \
 266                 "       li %0, %4\n"                            \
 267                 "       jump 2b, %1\n"                          \
 268                 "       .previous\n"                            \
 269                 "       .section __ex_table,\"a\"\n"            \
 270                 "       .balign " RISCV_SZPTR "\n"                      \
 271                 "       " RISCV_PTR " 1b, 3b\n"                 \
 272                 "       .previous"                              \
 273                 : "+r" (err), "=r" (__tmp), "=m" (*(ptr))       \
 274                 : "rJ" (__x), "i" (-EFAULT));                   \
 275         __disable_user_access();                                \
 276 } while (0)
 277
 278 #ifdef CONFIG_64BIT
 279 #define __put_user_8(x, ptr, err) \
 280         __put_user_asm("sd", x, ptr, err)
 281 #else /* !CONFIG_64BIT */
 282 #define __put_user_8(x, ptr, err)                               \
 283 do {                                                            \
 284         u32 __user *__ptr = (u32 __user *)(ptr);                \
 285         u64 __x = (__typeof__((x)-(x)))(x);                     \
 286         uintptr_t __tmp;                                        \
 287         __enable_user_access();                                 \
 288         __asm__ __volatile__ (                                  \
 289                 "1:\n"                                          \
 290                 "       sw %z4, %2\n"                           \
 291                 "2:\n"                                          \
 292                 "       sw %z5, %3\n"                           \
 293                 "3:\n"                                          \
 294                 "       .section .fixup,\"ax\"\n"               \
 295                 "       .balign 4\n"                            \
 296                 "4:\n"                                          \
 297                 "       li %0, %6\n"                            \
 298                 "       jump 3b, %1\n"                          \
 299                 "       .previous\n"                            \
 300                 "       .section __ex_table,\"a\"\n"            \
 301                 "       .balign " RISCV_SZPTR "\n"                      \
 302                 "       " RISCV_PTR " 1b, 4b\n"                 \
 303                 "       " RISCV_PTR " 2b, 4b\n"                 \
 304                 "       .previous"                              \
 305                 : "+r" (err), "=r" (__tmp),                     \
 306                         "=m" (__ptr[__LSW]),                    \
 307                         "=m" (__ptr[__MSW])                     \
 308                 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \
 309         __disable_user_access();                                \
 310 } while (0)
 311 #endif /* CONFIG_64BIT */
 312
 313
 314 /**
 315  * __put_user: - Write a simple value into user space, with less checking.
 316  * @x:   Value to copy to user space.
 317  * @ptr: Destination address, in user space.
 318  *
 319  * Context: User context only.  This function may sleep.
 320  *
 321  * This macro copies a single simple value from kernel space to user
 322  * space.  It supports simple types like char and int, but not larger
 323  * data types like structures or arrays.
 324  *
 325  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 326  * to the result of dereferencing @ptr.
 327  *
 328  * Caller must check the pointer with access_ok() before calling this
 329  * function.
 330  *
 331  * Returns zero on success, or -EFAULT on error.
 332  */
 333 #define __put_user(x, ptr)                                      \
 334 ({                                                              \
 335         register long __pu_err = 0;                             \
 336         __typeof__(*(ptr)) __user *__gu_ptr = (ptr);            \
 337         __chk_user_ptr(__gu_ptr);                               \
 338         switch (sizeof(*__gu_ptr)) {                            \
 339         case 1:                                                 \
 340                 __put_user_asm("sb", (x), __gu_ptr, __pu_err);  \
 341                 break;                                          \
 342         case 2:                                                 \
 343                 __put_user_asm("sh", (x), __gu_ptr, __pu_err);  \
 344                 break;                                          \
 345         case 4:                                                 \
 346                 __put_user_asm("sw", (x), __gu_ptr, __pu_err);  \
 347                 break;                                          \
 348         case 8:                                                 \
 349                 __put_user_8((x), __gu_ptr, __pu_err);  \
 350                 break;                                          \
 351         default:                                                \
 352                 BUILD_BUG();                                    \
 353         }                                                       \
 354         __pu_err;                                               \
 355 })
 356
 357 /**
 358  * put_user: - Write a simple value into user space.
 359  * @x:   Value to copy to user space.
 360  * @ptr: Destination address, in user space.
 361  *
 362  * Context: User context only.  This function may sleep.
 363  *
 364  * This macro copies a single simple value from kernel space to user
 365  * space.  It supports simple types like char and int, but not larger
 366  * data types like structures or arrays.
 367  *
 368  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 369  * to the result of dereferencing @ptr.
 370  *
 371  * Returns zero on success, or -EFAULT on error.
 372  */
 373 #define put_user(x, ptr)                                        \
 374 ({                                                              \
 375         __typeof__(*(ptr)) __user *__p = (ptr);                 \
 376         might_fault();                                          \
 377         access_ok(__p, sizeof(*__p)) ?          \
 378                 __put_user((x), __p) :                          \
 379                 -EFAULT;                                        \
 380 })
 381
 382
 383 extern unsigned long __must_check __asm_copy_to_user(void __user *to,
 384         const void *from, unsigned long n);
 385 extern unsigned long __must_check __asm_copy_from_user(void *to,
 386         const void __user *from, unsigned long n);
 387
 388 static inline unsigned long
 389 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 390 {
 391         return __asm_copy_from_user(to, from, n);
 392 }
 393
 394 static inline unsigned long
 395 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 396 {
 397         return __asm_copy_to_user(to, from, n);
 398 }
 399
 400 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 401
 402 extern long __must_check strlen_user(const char __user *str);
 403 extern long __must_check strnlen_user(const char __user *str, long n);
 404
 405 extern
 406 unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 407
 408 static inline
 409 unsigned long __must_check clear_user(void __user *to, unsigned long n)
 410 {
 411         might_fault();
 412         return access_ok(to, n) ?
 413                 __clear_user(to, n) : n;
 414 }
 415
 416 /*
 417  * Atomic compare-and-exchange, but with a fixup for userspace faults.  Faults
 418  * will set "err" to -EFAULT, while successful accesses return the previous
 419  * value.
 420  */
 421 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb)      \
 422 ({                                                              \
 423         __typeof__(ptr) __ptr = (ptr);                          \
 424         __typeof__(*(ptr)) __old = (old);                       \
 425         __typeof__(*(ptr)) __new = (new);                       \
 426         __typeof__(*(ptr)) __ret;                               \
 427         __typeof__(err) __err = 0;                              \
 428         register unsigned int __rc;                             \
 429         __enable_user_access();                                 \
 430         switch (size) {                                         \
 431         case 4:                                                 \
 432                 __asm__ __volatile__ (                          \
 433                 "0:\n"                                          \
 434                 "       lr.w" #scb " %[ret], %[ptr]\n"          \
 435                 "       bne          %[ret], %z[old], 1f\n"     \
 436                 "       sc.w" #lrb " %[rc], %z[new], %[ptr]\n"  \
 437                 "       bnez         %[rc], 0b\n"               \
 438                 "1:\n"                                          \
 439                 ".section .fixup,\"ax\"\n"                      \
 440                 ".balign 4\n"                                   \
 441                 "2:\n"                                          \
 442                 "       li %[err], %[efault]\n"                 \
 443                 "       jump 1b, %[rc]\n"                       \
 444                 ".previous\n"                                   \
 445                 ".section __ex_table,\"a\"\n"                   \
 446                 ".balign " RISCV_SZPTR "\n"                     \
 447                 "       " RISCV_PTR " 1b, 2b\n"                 \
 448                 ".previous\n"                                   \
 449                         : [ret] "=&r" (__ret),                  \
 450                           [rc]  "=&r" (__rc),                   \
 451                           [ptr] "+A" (*__ptr),                  \
 452                           [err] "=&r" (__err)                   \
 453                         : [old] "rJ" (__old),                   \
 454                           [new] "rJ" (__new),                   \
 455                           [efault] "i" (-EFAULT));              \
 456                 break;                                          \
 457         case 8:                                                 \
 458                 __asm__ __volatile__ (                          \
 459                 "0:\n"                                          \
 460                 "       lr.d" #scb " %[ret], %[ptr]\n"          \
 461                 "       bne          %[ret], %z[old], 1f\n"     \
 462                 "       sc.d" #lrb " %[rc], %z[new], %[ptr]\n"  \
 463                 "       bnez         %[rc], 0b\n"               \
 464                 "1:\n"                                          \
 465                 ".section .fixup,\"ax\"\n"                      \
 466                 ".balign 4\n"                                   \
 467                 "2:\n"                                          \
 468                 "       li %[err], %[efault]\n"                 \
 469                 "       jump 1b, %[rc]\n"                       \
 470                 ".previous\n"                                   \
 471                 ".section __ex_table,\"a\"\n"                   \
 472                 ".balign " RISCV_SZPTR "\n"                     \
 473                 "       " RISCV_PTR " 1b, 2b\n"                 \
 474                 ".previous\n"                                   \
 475                         : [ret] "=&r" (__ret),                  \
 476                           [rc]  "=&r" (__rc),                   \
 477                           [ptr] "+A" (*__ptr),                  \
 478                           [err] "=&r" (__err)                   \
 479                         : [old] "rJ" (__old),                   \
 480                           [new] "rJ" (__new),                   \
 481                           [efault] "i" (-EFAULT));              \
 482                 break;                                          \
 483         default:                                                \
 484                 BUILD_BUG();                                    \
 485         }                                                       \
 486         __disable_user_access();                                \
 487         (err) = __err;                                          \
 488         __ret;                                                  \
 489 })
 490
 491 #endif /* _ASM_RISCV_UACCESS_H */