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 #ifdef CONFIG_MMU
 131 #define __get_user_asm(insn, x, ptr, err)                       \
 132 do {                                                            \
 133         uintptr_t __tmp;                                        \
 134         __typeof__(x) __x;                                      \
 135         __enable_user_access();                                 \
 136         __asm__ __volatile__ (                                  \
 137                 "1:\n"                                          \
 138                 "       " insn " %1, %3\n"                      \
 139                 "2:\n"                                          \
 140                 "       .section .fixup,\"ax\"\n"               \
 141                 "       .balign 4\n"                            \
 142                 "3:\n"                                          \
 143                 "       li %0, %4\n"                            \
 144                 "       li %1, 0\n"                             \
 145                 "       jump 2b, %2\n"                          \
 146                 "       .previous\n"                            \
 147                 "       .section __ex_table,\"a\"\n"            \
 148                 "       .balign " RISCV_SZPTR "\n"                      \
 149                 "       " RISCV_PTR " 1b, 3b\n"                 \
 150                 "       .previous"                              \
 151                 : "+r" (err), "=&r" (__x), "=r" (__tmp)         \
 152                 : "m" (*(ptr)), "i" (-EFAULT));                 \
 153         __disable_user_access();                                \
 154         (x) = __x;                                              \
 155 } while (0)
 156 #endif /* CONFIG_MMU */
 157
 158 #ifdef CONFIG_64BIT
 159 #define __get_user_8(x, ptr, err) \
 160         __get_user_asm("ld", x, ptr, err)
 161 #else /* !CONFIG_64BIT */
 162 #ifdef CONFIG_MMU
 163 #define __get_user_8(x, ptr, err)                               \
 164 do {                                                            \
 165         u32 __user *__ptr = (u32 __user *)(ptr);                \
 166         u32 __lo, __hi;                                         \
 167         uintptr_t __tmp;                                        \
 168         __enable_user_access();                                 \
 169         __asm__ __volatile__ (                                  \
 170                 "1:\n"                                          \
 171                 "       lw %1, %4\n"                            \
 172                 "2:\n"                                          \
 173                 "       lw %2, %5\n"                            \
 174                 "3:\n"                                          \
 175                 "       .section .fixup,\"ax\"\n"               \
 176                 "       .balign 4\n"                            \
 177                 "4:\n"                                          \
 178                 "       li %0, %6\n"                            \
 179                 "       li %1, 0\n"                             \
 180                 "       li %2, 0\n"                             \
 181                 "       jump 3b, %3\n"                          \
 182                 "       .previous\n"                            \
 183                 "       .section __ex_table,\"a\"\n"            \
 184                 "       .balign " RISCV_SZPTR "\n"                      \
 185                 "       " RISCV_PTR " 1b, 4b\n"                 \
 186                 "       " RISCV_PTR " 2b, 4b\n"                 \
 187                 "       .previous"                              \
 188                 : "+r" (err), "=&r" (__lo), "=r" (__hi),        \
 189                         "=r" (__tmp)                            \
 190                 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]),       \
 191                         "i" (-EFAULT));                         \
 192         __disable_user_access();                                \
 193         (x) = (__typeof__(x))((__typeof__((x)-(x)))(            \
 194                 (((u64)__hi << 32) | __lo)));                   \
 195 } while (0)
 196 #endif /* CONFIG_MMU */
 197 #endif /* CONFIG_64BIT */
 198
 199
 200 /**
 201  * __get_user: - Get a simple variable from user space, with less checking.
 202  * @x:   Variable to store result.
 203  * @ptr: Source address, in user space.
 204  *
 205  * Context: User context only.  This function may sleep.
 206  *
 207  * This macro copies a single simple variable from user space to kernel
 208  * space.  It supports simple types like char and int, but not larger
 209  * data types like structures or arrays.
 210  *
 211  * @ptr must have pointer-to-simple-variable type, and the result of
 212  * dereferencing @ptr must be assignable to @x without a cast.
 213  *
 214  * Caller must check the pointer with access_ok() before calling this
 215  * function.
 216  *
 217  * Returns zero on success, or -EFAULT on error.
 218  * On error, the variable @x is set to zero.
 219  */
 220 #define __get_user(x, ptr)                                      \
 221 ({                                                              \
 222         register long __gu_err = 0;                             \
 223         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);      \
 224         __chk_user_ptr(__gu_ptr);                               \
 225         switch (sizeof(*__gu_ptr)) {                            \
 226         case 1:                                                 \
 227                 __get_user_asm("lb", (x), __gu_ptr, __gu_err);  \
 228                 break;                                          \
 229         case 2:                                                 \
 230                 __get_user_asm("lh", (x), __gu_ptr, __gu_err);  \
 231                 break;                                          \
 232         case 4:                                                 \
 233                 __get_user_asm("lw", (x), __gu_ptr, __gu_err);  \
 234                 break;                                          \
 235         case 8:                                                 \
 236                 __get_user_8((x), __gu_ptr, __gu_err);  \
 237                 break;                                          \
 238         default:                                                \
 239                 BUILD_BUG();                                    \
 240         }                                                       \
 241         __gu_err;                                               \
 242 })
 243
 244 /**
 245  * get_user: - Get a simple variable from user space.
 246  * @x:   Variable to store result.
 247  * @ptr: Source address, in user space.
 248  *
 249  * Context: User context only.  This function may sleep.
 250  *
 251  * This macro copies a single simple variable from user space to kernel
 252  * space.  It supports simple types like char and int, but not larger
 253  * data types like structures or arrays.
 254  *
 255  * @ptr must have pointer-to-simple-variable type, and the result of
 256  * dereferencing @ptr must be assignable to @x without a cast.
 257  *
 258  * Returns zero on success, or -EFAULT on error.
 259  * On error, the variable @x is set to zero.
 260  */
 261 #define get_user(x, ptr)                                        \
 262 ({                                                              \
 263         const __typeof__(*(ptr)) __user *__p = (ptr);           \
 264         might_fault();                                          \
 265         access_ok(VERIFY_READ, __p, sizeof(*__p)) ?             \
 266                 __get_user((x), __p) :                          \
 267                 ((x) = 0, -EFAULT);                             \
 268 })
 269
 270
 271 #ifdef CONFIG_MMU
 272 #define __put_user_asm(insn, x, ptr, err)                       \
 273 do {                                                            \
 274         uintptr_t __tmp;                                        \
 275         __typeof__(*(ptr)) __x = x;                             \
 276         __enable_user_access();                                 \
 277         __asm__ __volatile__ (                                  \
 278                 "1:\n"                                          \
 279                 "       " insn " %z3, %2\n"                     \
 280                 "2:\n"                                          \
 281                 "       .section .fixup,\"ax\"\n"               \
 282                 "       .balign 4\n"                            \
 283                 "3:\n"                                          \
 284                 "       li %0, %4\n"                            \
 285                 "       jump 2b, %1\n"                          \
 286                 "       .previous\n"                            \
 287                 "       .section __ex_table,\"a\"\n"            \
 288                 "       .balign " RISCV_SZPTR "\n"                      \
 289                 "       " RISCV_PTR " 1b, 3b\n"                 \
 290                 "       .previous"                              \
 291                 : "+r" (err), "=r" (__tmp), "=m" (*(ptr))       \
 292                 : "rJ" (__x), "i" (-EFAULT));                   \
 293         __disable_user_access();                                \
 294 } while (0)
 295 #endif /* CONFIG_MMU */
 296
 297
 298 #ifdef CONFIG_64BIT
 299 #define __put_user_8(x, ptr, err) \
 300         __put_user_asm("sd", x, ptr, err)
 301 #else /* !CONFIG_64BIT */
 302 #ifdef CONFIG_MMU
 303 #define __put_user_8(x, ptr, err)                               \
 304 do {                                                            \
 305         u32 __user *__ptr = (u32 __user *)(ptr);                \
 306         u64 __x = (__typeof__((x)-(x)))(x);                     \
 307         uintptr_t __tmp;                                        \
 308         __enable_user_access();                                 \
 309         __asm__ __volatile__ (                                  \
 310                 "1:\n"                                          \
 311                 "       sw %z4, %2\n"                           \
 312                 "2:\n"                                          \
 313                 "       sw %z5, %3\n"                           \
 314                 "3:\n"                                          \
 315                 "       .section .fixup,\"ax\"\n"               \
 316                 "       .balign 4\n"                            \
 317                 "4:\n"                                          \
 318                 "       li %0, %6\n"                            \
 319                 "       jump 2b, %1\n"                          \
 320                 "       .previous\n"                            \
 321                 "       .section __ex_table,\"a\"\n"            \
 322                 "       .balign " RISCV_SZPTR "\n"                      \
 323                 "       " RISCV_PTR " 1b, 4b\n"                 \
 324                 "       " RISCV_PTR " 2b, 4b\n"                 \
 325                 "       .previous"                              \
 326                 : "+r" (err), "=r" (__tmp),                     \
 327                         "=m" (__ptr[__LSW]),                    \
 328                         "=m" (__ptr[__MSW])                     \
 329                 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \
 330         __disable_user_access();                                \
 331 } while (0)
 332 #endif /* CONFIG_MMU */
 333 #endif /* CONFIG_64BIT */
 334
 335
 336 /**
 337  * __put_user: - Write a simple value into user space, with less checking.
 338  * @x:   Value to copy to user space.
 339  * @ptr: Destination address, in user space.
 340  *
 341  * Context: User context only.  This function may sleep.
 342  *
 343  * This macro copies a single simple value from kernel space to user
 344  * space.  It supports simple types like char and int, but not larger
 345  * data types like structures or arrays.
 346  *
 347  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 348  * to the result of dereferencing @ptr.
 349  *
 350  * Caller must check the pointer with access_ok() before calling this
 351  * function.
 352  *
 353  * Returns zero on success, or -EFAULT on error.
 354  */
 355 #define __put_user(x, ptr)                                      \
 356 ({                                                              \
 357         register long __pu_err = 0;                             \
 358         __typeof__(*(ptr)) __user *__gu_ptr = (ptr);            \
 359         __chk_user_ptr(__gu_ptr);                               \
 360         switch (sizeof(*__gu_ptr)) {                            \
 361         case 1:                                                 \
 362                 __put_user_asm("sb", (x), __gu_ptr, __pu_err);  \
 363                 break;                                          \
 364         case 2:                                                 \
 365                 __put_user_asm("sh", (x), __gu_ptr, __pu_err);  \
 366                 break;                                          \
 367         case 4:                                                 \
 368                 __put_user_asm("sw", (x), __gu_ptr, __pu_err);  \
 369                 break;                                          \
 370         case 8:                                                 \
 371                 __put_user_8((x), __gu_ptr, __pu_err);  \
 372                 break;                                          \
 373         default:                                                \
 374                 BUILD_BUG();                                    \
 375         }                                                       \
 376         __pu_err;                                               \
 377 })
 378
 379 /**
 380  * put_user: - Write a simple value into user space.
 381  * @x:   Value to copy to user space.
 382  * @ptr: Destination address, in user space.
 383  *
 384  * Context: User context only.  This function may sleep.
 385  *
 386  * This macro copies a single simple value from kernel space to user
 387  * space.  It supports simple types like char and int, but not larger
 388  * data types like structures or arrays.
 389  *
 390  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 391  * to the result of dereferencing @ptr.
 392  *
 393  * Returns zero on success, or -EFAULT on error.
 394  */
 395 #define put_user(x, ptr)                                        \
 396 ({                                                              \
 397         __typeof__(*(ptr)) __user *__p = (ptr);                 \
 398         might_fault();                                          \
 399         access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ?            \
 400                 __put_user((x), __p) :                          \
 401                 -EFAULT;                                        \
 402 })
 403
 404
 405 extern unsigned long __must_check __copy_user(void __user *to,
 406         const void __user *from, unsigned long n);
 407
 408 static inline unsigned long
 409 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 410 {
 411         return __copy_user(to, from, n);
 412 }
 413
 414 static inline unsigned long
 415 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 416 {
 417         return __copy_user(to, from, n);
 418 }
 419
 420 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 421
 422 extern long __must_check strlen_user(const char __user *str);
 423 extern long __must_check strnlen_user(const char __user *str, long n);
 424
 425 extern
 426 unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 427
 428 static inline
 429 unsigned long __must_check clear_user(void __user *to, unsigned long n)
 430 {
 431         might_fault();
 432         return access_ok(VERIFY_WRITE, to, n) ?
 433                 __clear_user(to, n) : n;
 434 }
 435
 436 /*
 437  * Atomic compare-and-exchange, but with a fixup for userspace faults.  Faults
 438  * will set "err" to -EFAULT, while successful accesses return the previous
 439  * value.
 440  */
 441 #ifdef CONFIG_MMU
 442 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb)      \
 443 ({                                                              \
 444         __typeof__(ptr) __ptr = (ptr);                          \
 445         __typeof__(*(ptr)) __old = (old);                       \
 446         __typeof__(*(ptr)) __new = (new);                       \
 447         __typeof__(*(ptr)) __ret;                               \
 448         __typeof__(err) __err = 0;                              \
 449         register unsigned int __rc;                             \
 450         __enable_user_access();                                 \
 451         switch (size) {                                         \
 452         case 4:                                                 \
 453                 __asm__ __volatile__ (                          \
 454                 "0:\n"                                          \
 455                 "       lr.w" #scb " %[ret], %[ptr]\n"          \
 456                 "       bne          %[ret], %z[old], 1f\n"     \
 457                 "       sc.w" #lrb " %[rc], %z[new], %[ptr]\n"  \
 458                 "       bnez         %[rc], 0b\n"               \
 459                 "1:\n"                                          \
 460                 ".section .fixup,\"ax\"\n"                      \
 461                 ".balign 4\n"                                   \
 462                 "2:\n"                                          \
 463                 "       li %[err], %[efault]\n"                 \
 464                 "       jump 1b, %[rc]\n"                       \
 465                 ".previous\n"                                   \
 466                 ".section __ex_table,\"a\"\n"                   \
 467                 ".balign " RISCV_SZPTR "\n"                     \
 468                 "       " RISCV_PTR " 1b, 2b\n"                 \
 469                 ".previous\n"                                   \
 470                         : [ret] "=&r" (__ret),                  \
 471                           [rc]  "=&r" (__rc),                   \
 472                           [ptr] "+A" (*__ptr),                  \
 473                           [err] "=&r" (__err)                   \
 474                         : [old] "rJ" (__old),                   \
 475                           [new] "rJ" (__new),                   \
 476                           [efault] "i" (-EFAULT));              \
 477                 break;                                          \
 478         case 8:                                                 \
 479                 __asm__ __volatile__ (                          \
 480                 "0:\n"                                          \
 481                 "       lr.d" #scb " %[ret], %[ptr]\n"          \
 482                 "       bne          %[ret], %z[old], 1f\n"     \
 483                 "       sc.d" #lrb " %[rc], %z[new], %[ptr]\n"  \
 484                 "       bnez         %[rc], 0b\n"               \
 485                 "1:\n"                                          \
 486                 ".section .fixup,\"ax\"\n"                      \
 487                 ".balign 4\n"                                   \
 488                 "2:\n"                                          \
 489                 "       li %[err], %[efault]\n"                 \
 490                 "       jump 1b, %[rc]\n"                       \
 491                 ".previous\n"                                   \
 492                 ".section __ex_table,\"a\"\n"                   \
 493                 ".balign " RISCV_SZPTR "\n"                     \
 494                 "       " RISCV_PTR " 1b, 2b\n"                 \
 495                 ".previous\n"                                   \
 496                         : [ret] "=&r" (__ret),                  \
 497                           [rc]  "=&r" (__rc),                   \
 498                           [ptr] "+A" (*__ptr),                  \
 499                           [err] "=&r" (__err)                   \
 500                         : [old] "rJ" (__old),                   \
 501                           [new] "rJ" (__new),                   \
 502                           [efault] "i" (-EFAULT));              \
 503                 break;                                          \
 504         default:                                                \
 505                 BUILD_BUG();                                    \
 506         }                                                       \
 507         __disable_user_access();                                \
 508         (err) = __err;                                          \
 509         __ret;                                                  \
 510 })
 511 #endif /* CONFIG_MMU */
 512
 513 #endif /* _ASM_RISCV_UACCESS_H */