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 #define VERIFY_READ     0
  58 #define VERIFY_WRITE    1
  59
  60 /**
  61  * access_ok: - Checks if a user space pointer is valid
  62  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  63  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  64  *        to write to a block, it is always safe to read from it.
  65  * @addr: User space pointer to start of block to check
  66  * @size: Size of block to check
  67  *
  68  * Context: User context only.  This function may sleep.
  69  *
  70  * Checks if a pointer to a block of memory in user space is valid.
  71  *
  72  * Returns true (nonzero) if the memory block may be valid, false (zero)
  73  * if it is definitely invalid.
  74  *
  75  * Note that, depending on architecture, this function probably just
  76  * checks that the pointer is in the user space range - after calling
  77  * this function, memory access functions may still return -EFAULT.
  78  */
  79 #define access_ok(type, addr, size) ({                                  \
  80         __chk_user_ptr(addr);                                           \
  81         likely(__access_ok((unsigned long __force)(addr), (size)));     \
  82 })
  83
  84 /*
  85  * Ensure that the range [addr, addr+size) is within the process's
  86  * address space
  87  */
  88 static inline int __access_ok(unsigned long addr, unsigned long size)
  89 {
  90         const mm_segment_t fs = get_fs();
  91
  92         return (size <= fs) && (addr <= (fs - size));
  93 }
  94
  95 /*
  96  * The exception table consists of pairs of addresses: the first is the
  97  * address of an instruction that is allowed to fault, and the second is
  98  * the address at which the program should continue.  No registers are
  99  * modified, so it is entirely up to the continuation code to figure out
 100  * what to do.
 101  *
 102  * All the routines below use bits of fixup code that are out of line
 103  * with the main instruction path.  This means when everything is well,
 104  * we don't even have to jump over them.  Further, they do not intrude
 105  * on our cache or tlb entries.
 106  */
 107
 108 struct exception_table_entry {
 109         unsigned long insn, fixup;
 110 };
 111
 112 extern int fixup_exception(struct pt_regs *state);
 113
 114 #if defined(__LITTLE_ENDIAN)
 115 #define __MSW   1
 116 #define __LSW   0
 117 #elif defined(__BIG_ENDIAN)
 118 #define __MSW   0
 119 #define __LSW   1
 120 #else
 121 #error "Unknown endianness"
 122 #endif
 123
 124 /*
 125  * The "__xxx" versions of the user access functions do not verify the address
 126  * space - it must have been done previously with a separate "access_ok()"
 127  * call.
 128  */
 129
 130 #define __get_user_asm(insn, x, ptr, err)                       \
 131 do {                                                            \
 132         uintptr_t __tmp;                                        \
 133         __typeof__(x) __x;                                      \
 134         __enable_user_access();                                 \
 135         __asm__ __volatile__ (                                  \
 136                 "1:\n"                                          \
 137                 "       " insn " %1, %3\n"                      \
 138                 "2:\n"                                          \
 139                 "       .section .fixup,\"ax\"\n"               \
 140                 "       .balign 4\n"                            \
 141                 "3:\n"                                          \
 142                 "       li %0, %4\n"                            \
 143                 "       li %1, 0\n"                             \
 144                 "       jump 2b, %2\n"                          \
 145                 "       .previous\n"                            \
 146                 "       .section __ex_table,\"a\"\n"            \
 147                 "       .balign " RISCV_SZPTR "\n"                      \
 148                 "       " RISCV_PTR " 1b, 3b\n"                 \
 149                 "       .previous"                              \
 150                 : "+r" (err), "=&r" (__x), "=r" (__tmp)         \
 151                 : "m" (*(ptr)), "i" (-EFAULT));                 \
 152         __disable_user_access();                                \
 153         (x) = __x;                                              \
 154 } while (0)
 155
 156 #ifdef CONFIG_64BIT
 157 #define __get_user_8(x, ptr, err) \
 158         __get_user_asm("ld", x, ptr, err)
 159 #else /* !CONFIG_64BIT */
 160 #define __get_user_8(x, ptr, err)                               \
 161 do {                                                            \
 162         u32 __user *__ptr = (u32 __user *)(ptr);                \
 163         u32 __lo, __hi;                                         \
 164         uintptr_t __tmp;                                        \
 165         __enable_user_access();                                 \
 166         __asm__ __volatile__ (                                  \
 167                 "1:\n"                                          \
 168                 "       lw %1, %4\n"                            \
 169                 "2:\n"                                          \
 170                 "       lw %2, %5\n"                            \
 171                 "3:\n"                                          \
 172                 "       .section .fixup,\"ax\"\n"               \
 173                 "       .balign 4\n"                            \
 174                 "4:\n"                                          \
 175                 "       li %0, %6\n"                            \
 176                 "       li %1, 0\n"                             \
 177                 "       li %2, 0\n"                             \
 178                 "       jump 3b, %3\n"                          \
 179                 "       .previous\n"                            \
 180                 "       .section __ex_table,\"a\"\n"            \
 181                 "       .balign " RISCV_SZPTR "\n"                      \
 182                 "       " RISCV_PTR " 1b, 4b\n"                 \
 183                 "       " RISCV_PTR " 2b, 4b\n"                 \
 184                 "       .previous"                              \
 185                 : "+r" (err), "=&r" (__lo), "=r" (__hi),        \
 186                         "=r" (__tmp)                            \
 187                 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]),       \
 188                         "i" (-EFAULT));                         \
 189         __disable_user_access();                                \
 190         (x) = (__typeof__(x))((__typeof__((x)-(x)))(            \
 191                 (((u64)__hi << 32) | __lo)));                   \
 192 } while (0)
 193 #endif /* CONFIG_64BIT */
 194
 195
 196 /**
 197  * __get_user: - Get a simple variable from user space, with less checking.
 198  * @x:   Variable to store result.
 199  * @ptr: Source address, in user space.
 200  *
 201  * Context: User context only.  This function may sleep.
 202  *
 203  * This macro copies a single simple variable from user space to kernel
 204  * space.  It supports simple types like char and int, but not larger
 205  * data types like structures or arrays.
 206  *
 207  * @ptr must have pointer-to-simple-variable type, and the result of
 208  * dereferencing @ptr must be assignable to @x without a cast.
 209  *
 210  * Caller must check the pointer with access_ok() before calling this
 211  * function.
 212  *
 213  * Returns zero on success, or -EFAULT on error.
 214  * On error, the variable @x is set to zero.
 215  */
 216 #define __get_user(x, ptr)                                      \
 217 ({                                                              \
 218         register long __gu_err = 0;                             \
 219         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);      \
 220         __chk_user_ptr(__gu_ptr);                               \
 221         switch (sizeof(*__gu_ptr)) {                            \
 222         case 1:                                                 \
 223                 __get_user_asm("lb", (x), __gu_ptr, __gu_err);  \
 224                 break;                                          \
 225         case 2:                                                 \
 226                 __get_user_asm("lh", (x), __gu_ptr, __gu_err);  \
 227                 break;                                          \
 228         case 4:                                                 \
 229                 __get_user_asm("lw", (x), __gu_ptr, __gu_err);  \
 230                 break;                                          \
 231         case 8:                                                 \
 232                 __get_user_8((x), __gu_ptr, __gu_err);  \
 233                 break;                                          \
 234         default:                                                \
 235                 BUILD_BUG();                                    \
 236         }                                                       \
 237         __gu_err;                                               \
 238 })
 239
 240 /**
 241  * get_user: - Get a simple variable from user space.
 242  * @x:   Variable to store result.
 243  * @ptr: Source address, in user space.
 244  *
 245  * Context: User context only.  This function may sleep.
 246  *
 247  * This macro copies a single simple variable from user space to kernel
 248  * space.  It supports simple types like char and int, but not larger
 249  * data types like structures or arrays.
 250  *
 251  * @ptr must have pointer-to-simple-variable type, and the result of
 252  * dereferencing @ptr must be assignable to @x without a cast.
 253  *
 254  * Returns zero on success, or -EFAULT on error.
 255  * On error, the variable @x is set to zero.
 256  */
 257 #define get_user(x, ptr)                                        \
 258 ({                                                              \
 259         const __typeof__(*(ptr)) __user *__p = (ptr);           \
 260         might_fault();                                          \
 261         access_ok(VERIFY_READ, __p, sizeof(*__p)) ?             \
 262                 __get_user((x), __p) :                          \
 263                 ((x) = 0, -EFAULT);                             \
 264 })
 265
 266 #define __put_user_asm(insn, x, ptr, err)                       \
 267 do {                                                            \
 268         uintptr_t __tmp;                                        \
 269         __typeof__(*(ptr)) __x = x;                             \
 270         __enable_user_access();                                 \
 271         __asm__ __volatile__ (                                  \
 272                 "1:\n"                                          \
 273                 "       " insn " %z3, %2\n"                     \
 274                 "2:\n"                                          \
 275                 "       .section .fixup,\"ax\"\n"               \
 276                 "       .balign 4\n"                            \
 277                 "3:\n"                                          \
 278                 "       li %0, %4\n"                            \
 279                 "       jump 2b, %1\n"                          \
 280                 "       .previous\n"                            \
 281                 "       .section __ex_table,\"a\"\n"            \
 282                 "       .balign " RISCV_SZPTR "\n"                      \
 283                 "       " RISCV_PTR " 1b, 3b\n"                 \
 284                 "       .previous"                              \
 285                 : "+r" (err), "=r" (__tmp), "=m" (*(ptr))       \
 286                 : "rJ" (__x), "i" (-EFAULT));                   \
 287         __disable_user_access();                                \
 288 } while (0)
 289
 290 #ifdef CONFIG_64BIT
 291 #define __put_user_8(x, ptr, err) \
 292         __put_user_asm("sd", x, ptr, err)
 293 #else /* !CONFIG_64BIT */
 294 #define __put_user_8(x, ptr, err)                               \
 295 do {                                                            \
 296         u32 __user *__ptr = (u32 __user *)(ptr);                \
 297         u64 __x = (__typeof__((x)-(x)))(x);                     \
 298         uintptr_t __tmp;                                        \
 299         __enable_user_access();                                 \
 300         __asm__ __volatile__ (                                  \
 301                 "1:\n"                                          \
 302                 "       sw %z4, %2\n"                           \
 303                 "2:\n"                                          \
 304                 "       sw %z5, %3\n"                           \
 305                 "3:\n"                                          \
 306                 "       .section .fixup,\"ax\"\n"               \
 307                 "       .balign 4\n"                            \
 308                 "4:\n"                                          \
 309                 "       li %0, %6\n"                            \
 310                 "       jump 2b, %1\n"                          \
 311                 "       .previous\n"                            \
 312                 "       .section __ex_table,\"a\"\n"            \
 313                 "       .balign " RISCV_SZPTR "\n"                      \
 314                 "       " RISCV_PTR " 1b, 4b\n"                 \
 315                 "       " RISCV_PTR " 2b, 4b\n"                 \
 316                 "       .previous"                              \
 317                 : "+r" (err), "=r" (__tmp),                     \
 318                         "=m" (__ptr[__LSW]),                    \
 319                         "=m" (__ptr[__MSW])                     \
 320                 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \
 321         __disable_user_access();                                \
 322 } while (0)
 323 #endif /* CONFIG_64BIT */
 324
 325
 326 /**
 327  * __put_user: - Write a simple value into user space, with less checking.
 328  * @x:   Value to copy to user space.
 329  * @ptr: Destination address, in user space.
 330  *
 331  * Context: User context only.  This function may sleep.
 332  *
 333  * This macro copies a single simple value from kernel space to user
 334  * space.  It supports simple types like char and int, but not larger
 335  * data types like structures or arrays.
 336  *
 337  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 338  * to the result of dereferencing @ptr.
 339  *
 340  * Caller must check the pointer with access_ok() before calling this
 341  * function.
 342  *
 343  * Returns zero on success, or -EFAULT on error.
 344  */
 345 #define __put_user(x, ptr)                                      \
 346 ({                                                              \
 347         register long __pu_err = 0;                             \
 348         __typeof__(*(ptr)) __user *__gu_ptr = (ptr);            \
 349         __chk_user_ptr(__gu_ptr);                               \
 350         switch (sizeof(*__gu_ptr)) {                            \
 351         case 1:                                                 \
 352                 __put_user_asm("sb", (x), __gu_ptr, __pu_err);  \
 353                 break;                                          \
 354         case 2:                                                 \
 355                 __put_user_asm("sh", (x), __gu_ptr, __pu_err);  \
 356                 break;                                          \
 357         case 4:                                                 \
 358                 __put_user_asm("sw", (x), __gu_ptr, __pu_err);  \
 359                 break;                                          \
 360         case 8:                                                 \
 361                 __put_user_8((x), __gu_ptr, __pu_err);  \
 362                 break;                                          \
 363         default:                                                \
 364                 BUILD_BUG();                                    \
 365         }                                                       \
 366         __pu_err;                                               \
 367 })
 368
 369 /**
 370  * put_user: - Write a simple value into user space.
 371  * @x:   Value to copy to user space.
 372  * @ptr: Destination address, in user space.
 373  *
 374  * Context: User context only.  This function may sleep.
 375  *
 376  * This macro copies a single simple value from kernel space to user
 377  * space.  It supports simple types like char and int, but not larger
 378  * data types like structures or arrays.
 379  *
 380  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 381  * to the result of dereferencing @ptr.
 382  *
 383  * Returns zero on success, or -EFAULT on error.
 384  */
 385 #define put_user(x, ptr)                                        \
 386 ({                                                              \
 387         __typeof__(*(ptr)) __user *__p = (ptr);                 \
 388         might_fault();                                          \
 389         access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ?            \
 390                 __put_user((x), __p) :                          \
 391                 -EFAULT;                                        \
 392 })
 393
 394
 395 extern unsigned long __must_check __asm_copy_to_user(void __user *to,
 396         const void *from, unsigned long n);
 397 extern unsigned long __must_check __asm_copy_from_user(void *to,
 398         const void __user *from, unsigned long n);
 399
 400 static inline unsigned long
 401 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 402 {
 403         return __asm_copy_to_user(to, from, n);
 404 }
 405
 406 static inline unsigned long
 407 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 408 {
 409         return __asm_copy_from_user(to, from, n);
 410 }
 411
 412 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 413
 414 extern long __must_check strlen_user(const char __user *str);
 415 extern long __must_check strnlen_user(const char __user *str, long n);
 416
 417 extern
 418 unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 419
 420 static inline
 421 unsigned long __must_check clear_user(void __user *to, unsigned long n)
 422 {
 423         might_fault();
 424         return access_ok(VERIFY_WRITE, to, n) ?
 425                 __clear_user(to, n) : n;
 426 }
 427
 428 /*
 429  * Atomic compare-and-exchange, but with a fixup for userspace faults.  Faults
 430  * will set "err" to -EFAULT, while successful accesses return the previous
 431  * value.
 432  */
 433 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb)      \
 434 ({                                                              \
 435         __typeof__(ptr) __ptr = (ptr);                          \
 436         __typeof__(*(ptr)) __old = (old);                       \
 437         __typeof__(*(ptr)) __new = (new);                       \
 438         __typeof__(*(ptr)) __ret;                               \
 439         __typeof__(err) __err = 0;                              \
 440         register unsigned int __rc;                             \
 441         __enable_user_access();                                 \
 442         switch (size) {                                         \
 443         case 4:                                                 \
 444                 __asm__ __volatile__ (                          \
 445                 "0:\n"                                          \
 446                 "       lr.w" #scb " %[ret], %[ptr]\n"          \
 447                 "       bne          %[ret], %z[old], 1f\n"     \
 448                 "       sc.w" #lrb " %[rc], %z[new], %[ptr]\n"  \
 449                 "       bnez         %[rc], 0b\n"               \
 450                 "1:\n"                                          \
 451                 ".section .fixup,\"ax\"\n"                      \
 452                 ".balign 4\n"                                   \
 453                 "2:\n"                                          \
 454                 "       li %[err], %[efault]\n"                 \
 455                 "       jump 1b, %[rc]\n"                       \
 456                 ".previous\n"                                   \
 457                 ".section __ex_table,\"a\"\n"                   \
 458                 ".balign " RISCV_SZPTR "\n"                     \
 459                 "       " RISCV_PTR " 1b, 2b\n"                 \
 460                 ".previous\n"                                   \
 461                         : [ret] "=&r" (__ret),                  \
 462                           [rc]  "=&r" (__rc),                   \
 463                           [ptr] "+A" (*__ptr),                  \
 464                           [err] "=&r" (__err)                   \
 465                         : [old] "rJ" (__old),                   \
 466                           [new] "rJ" (__new),                   \
 467                           [efault] "i" (-EFAULT));              \
 468                 break;                                          \
 469         case 8:                                                 \
 470                 __asm__ __volatile__ (                          \
 471                 "0:\n"                                          \
 472                 "       lr.d" #scb " %[ret], %[ptr]\n"          \
 473                 "       bne          %[ret], %z[old], 1f\n"     \
 474                 "       sc.d" #lrb " %[rc], %z[new], %[ptr]\n"  \
 475                 "       bnez         %[rc], 0b\n"               \
 476                 "1:\n"                                          \
 477                 ".section .fixup,\"ax\"\n"                      \
 478                 ".balign 4\n"                                   \
 479                 "2:\n"                                          \
 480                 "       li %[err], %[efault]\n"                 \
 481                 "       jump 1b, %[rc]\n"                       \
 482                 ".previous\n"                                   \
 483                 ".section __ex_table,\"a\"\n"                   \
 484                 ".balign " RISCV_SZPTR "\n"                     \
 485                 "       " RISCV_PTR " 1b, 2b\n"                 \
 486                 ".previous\n"                                   \
 487                         : [ret] "=&r" (__ret),                  \
 488                           [rc]  "=&r" (__rc),                   \
 489                           [ptr] "+A" (*__ptr),                  \
 490                           [err] "=&r" (__err)                   \
 491                         : [old] "rJ" (__old),                   \
 492                           [new] "rJ" (__new),                   \
 493                           [efault] "i" (-EFAULT));              \
 494                 break;                                          \
 495         default:                                                \
 496                 BUILD_BUG();                                    \
 497         }                                                       \
 498         __disable_user_access();                                \
 499         (err) = __err;                                          \
 500         __ret;                                                  \
 501 })
 502
 503 #endif /* _ASM_RISCV_UACCESS_H */