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