arch/riscv/include/asm/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2012 Regents of the University of California
   4  *
   5  * This file was copied from include/asm-generic/uaccess.h
   6  */
   7
   8 #ifndef _ASM_RISCV_UACCESS_H
   9 #define _ASM_RISCV_UACCESS_H
  10
  11 #include <asm/pgtable.h>                /* for TASK_SIZE */
  12
  13 /*
  14  * User space memory access functions
  15  */
  16
  17 extern unsigned long __must_check __asm_copy_to_user(void __user *to,
  18         const void *from, unsigned long n);
  19 extern unsigned long __must_check __asm_copy_from_user(void *to,
  20         const void __user *from, unsigned long n);
  21
  22 static inline unsigned long
  23 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
  24 {
  25         return __asm_copy_from_user(to, from, n);
  26 }
  27
  28 static inline unsigned long
  29 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
  30 {
  31         return __asm_copy_to_user(to, from, n);
  32 }
  33
  34 #ifdef CONFIG_MMU
  35 #include <linux/errno.h>
  36 #include <linux/compiler.h>
  37 #include <linux/thread_info.h>
  38 #include <asm/byteorder.h>
  39 #include <asm/extable.h>
  40 #include <asm/asm.h>
  41
  42 #define __enable_user_access()                                                  \
  43         __asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory")
  44 #define __disable_user_access()                                                 \
  45         __asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")
  46
  47 /*
  48  * The fs value determines whether argument validity checking should be
  49  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  50  * get_fs() == KERNEL_DS, checking is bypassed.
  51  *
  52  * For historical reasons, these macros are grossly misnamed.
  53  */
  54
  55 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  56
  57 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
  58 #define USER_DS         MAKE_MM_SEG(TASK_SIZE)
  59
  60 #define get_fs()        (current_thread_info()->addr_limit)
  61
  62 static inline void set_fs(mm_segment_t fs)
  63 {
  64         current_thread_info()->addr_limit = fs;
  65 }
  66
  67 #define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
  68 #define user_addr_max() (get_fs().seg)
  69
  70 /**
  71  * access_ok: - Checks if a user space pointer is valid
  72  * @addr: User space pointer to start of block to check
  73  * @size: Size of block to check
  74  *
  75  * Context: User context only.  This function may sleep.
  76  *
  77  * Checks if a pointer to a block of memory in user space is valid.
  78  *
  79  * Returns true (nonzero) if the memory block may be valid, false (zero)
  80  * if it is definitely invalid.
  81  *
  82  * Note that, depending on architecture, this function probably just
  83  * checks that the pointer is in the user space range - after calling
  84  * this function, memory access functions may still return -EFAULT.
  85  */
  86 #define access_ok(addr, size) ({                                        \
  87         __chk_user_ptr(addr);                                           \
  88         likely(__access_ok((unsigned long __force)(addr), (size)));     \
  89 })
  90
  91 /*
  92  * Ensure that the range [addr, addr+size) is within the process's
  93  * address space
  94  */
  95 static inline int __access_ok(unsigned long addr, unsigned long size)
  96 {
  97         const mm_segment_t fs = get_fs();
  98
  99         return size <= fs.seg && addr <= fs.seg - size;
 100 }
 101
 102 /*
 103  * The exception table consists of pairs of addresses: the first is the
 104  * address of an instruction that is allowed to fault, and the second is
 105  * the address at which the program should continue.  No registers are
 106  * modified, so it is entirely up to the continuation code to figure out
 107  * what to do.
 108  *
 109  * All the routines below use bits of fixup code that are out of line
 110  * with the main instruction path.  This means when everything is well,
 111  * we don't even have to jump over them.  Further, they do not intrude
 112  * on our cache or tlb entries.
 113  */
 114
 115 #define __LSW   0
 116 #define __MSW   1
 117
 118 /*
 119  * The "__xxx" versions of the user access functions do not verify the address
 120  * space - it must have been done previously with a separate "access_ok()"
 121  * call.
 122  */
 123
 124 #define __get_user_asm(insn, x, ptr, err)                       \
 125 do {                                                            \
 126         uintptr_t __tmp;                                        \
 127         __typeof__(x) __x;                                      \
 128         __enable_user_access();                                 \
 129         __asm__ __volatile__ (                                  \
 130                 "1:\n"                                          \
 131                 "       " insn " %1, %3\n"                      \
 132                 "2:\n"                                          \
 133                 "       .section .fixup,\"ax\"\n"               \
 134                 "       .balign 4\n"                            \
 135                 "3:\n"                                          \
 136                 "       li %0, %4\n"                            \
 137                 "       li %1, 0\n"                             \
 138                 "       jump 2b, %2\n"                          \
 139                 "       .previous\n"                            \
 140                 "       .section __ex_table,\"a\"\n"            \
 141                 "       .balign " RISCV_SZPTR "\n"                      \
 142                 "       " RISCV_PTR " 1b, 3b\n"                 \
 143                 "       .previous"                              \
 144                 : "+r" (err), "=&r" (__x), "=r" (__tmp)         \
 145                 : "m" (*(ptr)), "i" (-EFAULT));                 \
 146         __disable_user_access();                                \
 147         (x) = __x;                                              \
 148 } while (0)
 149
 150 #ifdef CONFIG_64BIT
 151 #define __get_user_8(x, ptr, err) \
 152         __get_user_asm("ld", x, ptr, err)
 153 #else /* !CONFIG_64BIT */
 154 #define __get_user_8(x, ptr, err)                               \
 155 do {                                                            \
 156         u32 __user *__ptr = (u32 __user *)(ptr);                \
 157         u32 __lo, __hi;                                         \
 158         uintptr_t __tmp;                                        \
 159         __enable_user_access();                                 \
 160         __asm__ __volatile__ (                                  \
 161                 "1:\n"                                          \
 162                 "       lw %1, %4\n"                            \
 163                 "2:\n"                                          \
 164                 "       lw %2, %5\n"                            \
 165                 "3:\n"                                          \
 166                 "       .section .fixup,\"ax\"\n"               \
 167                 "       .balign 4\n"                            \
 168                 "4:\n"                                          \
 169                 "       li %0, %6\n"                            \
 170                 "       li %1, 0\n"                             \
 171                 "       li %2, 0\n"                             \
 172                 "       jump 3b, %3\n"                          \
 173                 "       .previous\n"                            \
 174                 "       .section __ex_table,\"a\"\n"            \
 175                 "       .balign " RISCV_SZPTR "\n"                      \
 176                 "       " RISCV_PTR " 1b, 4b\n"                 \
 177                 "       " RISCV_PTR " 2b, 4b\n"                 \
 178                 "       .previous"                              \
 179                 : "+r" (err), "=&r" (__lo), "=r" (__hi),        \
 180                         "=r" (__tmp)                            \
 181                 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]),       \
 182                         "i" (-EFAULT));                         \
 183         __disable_user_access();                                \
 184         (x) = (__typeof__(x))((__typeof__((x)-(x)))(            \
 185                 (((u64)__hi << 32) | __lo)));                   \
 186 } while (0)
 187 #endif /* CONFIG_64BIT */
 188
 189
 190 /**
 191  * __get_user: - Get a simple variable from user space, with less checking.
 192  * @x:   Variable to store result.
 193  * @ptr: Source address, in user space.
 194  *
 195  * Context: User context only.  This function may sleep.
 196  *
 197  * This macro copies a single simple variable from user space to kernel
 198  * space.  It supports simple types like char and int, but not larger
 199  * data types like structures or arrays.
 200  *
 201  * @ptr must have pointer-to-simple-variable type, and the result of
 202  * dereferencing @ptr must be assignable to @x without a cast.
 203  *
 204  * Caller must check the pointer with access_ok() before calling this
 205  * function.
 206  *
 207  * Returns zero on success, or -EFAULT on error.
 208  * On error, the variable @x is set to zero.
 209  */
 210 #define __get_user(x, ptr)                                      \
 211 ({                                                              \
 212         register long __gu_err = 0;                             \
 213         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);      \
 214         __chk_user_ptr(__gu_ptr);                               \
 215         switch (sizeof(*__gu_ptr)) {                            \
 216         case 1:                                                 \
 217                 __get_user_asm("lb", (x), __gu_ptr, __gu_err);  \
 218                 break;                                          \
 219         case 2:                                                 \
 220                 __get_user_asm("lh", (x), __gu_ptr, __gu_err);  \
 221                 break;                                          \
 222         case 4:                                                 \
 223                 __get_user_asm("lw", (x), __gu_ptr, __gu_err);  \
 224                 break;                                          \
 225         case 8:                                                 \
 226                 __get_user_8((x), __gu_ptr, __gu_err);  \
 227                 break;                                          \
 228         default:                                                \
 229                 BUILD_BUG();                                    \
 230         }                                                       \
 231         __gu_err;                                               \
 232 })
 233
 234 /**
 235  * get_user: - Get a simple variable from user space.
 236  * @x:   Variable to store result.
 237  * @ptr: Source address, in user space.
 238  *
 239  * Context: User context only.  This function may sleep.
 240  *
 241  * This macro copies a single simple variable from user space to kernel
 242  * space.  It supports simple types like char and int, but not larger
 243  * data types like structures or arrays.
 244  *
 245  * @ptr must have pointer-to-simple-variable type, and the result of
 246  * dereferencing @ptr must be assignable to @x without a cast.
 247  *
 248  * Returns zero on success, or -EFAULT on error.
 249  * On error, the variable @x is set to zero.
 250  */
 251 #define get_user(x, ptr)                                        \
 252 ({                                                              \
 253         const __typeof__(*(ptr)) __user *__p = (ptr);           \
 254         might_fault();                                          \
 255         access_ok(__p, sizeof(*__p)) ?          \
 256                 __get_user((x), __p) :                          \
 257                 ((x) = 0, -EFAULT);                             \
 258 })
 259
 260 #define __put_user_asm(insn, x, ptr, err)                       \
 261 do {                                                            \
 262         uintptr_t __tmp;                                        \
 263         __typeof__(*(ptr)) __x = x;                             \
 264         __enable_user_access();                                 \
 265         __asm__ __volatile__ (                                  \
 266                 "1:\n"                                          \
 267                 "       " insn " %z3, %2\n"                     \
 268                 "2:\n"                                          \
 269                 "       .section .fixup,\"ax\"\n"               \
 270                 "       .balign 4\n"                            \
 271                 "3:\n"                                          \
 272                 "       li %0, %4\n"                            \
 273                 "       jump 2b, %1\n"                          \
 274                 "       .previous\n"                            \
 275                 "       .section __ex_table,\"a\"\n"            \
 276                 "       .balign " RISCV_SZPTR "\n"                      \
 277                 "       " RISCV_PTR " 1b, 3b\n"                 \
 278                 "       .previous"                              \
 279                 : "+r" (err), "=r" (__tmp), "=m" (*(ptr))       \
 280                 : "rJ" (__x), "i" (-EFAULT));                   \
 281         __disable_user_access();                                \
 282 } while (0)
 283
 284 #ifdef CONFIG_64BIT
 285 #define __put_user_8(x, ptr, err) \
 286         __put_user_asm("sd", x, ptr, err)
 287 #else /* !CONFIG_64BIT */
 288 #define __put_user_8(x, ptr, err)                               \
 289 do {                                                            \
 290         u32 __user *__ptr = (u32 __user *)(ptr);                \
 291         u64 __x = (__typeof__((x)-(x)))(x);                     \
 292         uintptr_t __tmp;                                        \
 293         __enable_user_access();                                 \
 294         __asm__ __volatile__ (                                  \
 295                 "1:\n"                                          \
 296                 "       sw %z4, %2\n"                           \
 297                 "2:\n"                                          \
 298                 "       sw %z5, %3\n"                           \
 299                 "3:\n"                                          \
 300                 "       .section .fixup,\"ax\"\n"               \
 301                 "       .balign 4\n"                            \
 302                 "4:\n"                                          \
 303                 "       li %0, %6\n"                            \
 304                 "       jump 3b, %1\n"                          \
 305                 "       .previous\n"                            \
 306                 "       .section __ex_table,\"a\"\n"            \
 307                 "       .balign " RISCV_SZPTR "\n"                      \
 308                 "       " RISCV_PTR " 1b, 4b\n"                 \
 309                 "       " RISCV_PTR " 2b, 4b\n"                 \
 310                 "       .previous"                              \
 311                 : "+r" (err), "=r" (__tmp),                     \
 312                         "=m" (__ptr[__LSW]),                    \
 313                         "=m" (__ptr[__MSW])                     \
 314                 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \
 315         __disable_user_access();                                \
 316 } while (0)
 317 #endif /* CONFIG_64BIT */
 318
 319
 320 /**
 321  * __put_user: - Write a simple value into user space, with less checking.
 322  * @x:   Value to copy to user space.
 323  * @ptr: Destination address, in user space.
 324  *
 325  * Context: User context only.  This function may sleep.
 326  *
 327  * This macro copies a single simple value from kernel space to user
 328  * space.  It supports simple types like char and int, but not larger
 329  * data types like structures or arrays.
 330  *
 331  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 332  * to the result of dereferencing @ptr.
 333  *
 334  * Caller must check the pointer with access_ok() before calling this
 335  * function.
 336  *
 337  * Returns zero on success, or -EFAULT on error.
 338  */
 339 #define __put_user(x, ptr)                                      \
 340 ({                                                              \
 341         register long __pu_err = 0;                             \
 342         __typeof__(*(ptr)) __user *__gu_ptr = (ptr);            \
 343         __chk_user_ptr(__gu_ptr);                               \
 344         switch (sizeof(*__gu_ptr)) {                            \
 345         case 1:                                                 \
 346                 __put_user_asm("sb", (x), __gu_ptr, __pu_err);  \
 347                 break;                                          \
 348         case 2:                                                 \
 349                 __put_user_asm("sh", (x), __gu_ptr, __pu_err);  \
 350                 break;                                          \
 351         case 4:                                                 \
 352                 __put_user_asm("sw", (x), __gu_ptr, __pu_err);  \
 353                 break;                                          \
 354         case 8:                                                 \
 355                 __put_user_8((x), __gu_ptr, __pu_err);  \
 356                 break;                                          \
 357         default:                                                \
 358                 BUILD_BUG();                                    \
 359         }                                                       \
 360         __pu_err;                                               \
 361 })
 362
 363 /**
 364  * put_user: - Write a simple value into user space.
 365  * @x:   Value to copy to user space.
 366  * @ptr: Destination address, in user space.
 367  *
 368  * Context: User context only.  This function may sleep.
 369  *
 370  * This macro copies a single simple value from kernel space to user
 371  * space.  It supports simple types like char and int, but not larger
 372  * data types like structures or arrays.
 373  *
 374  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 375  * to the result of dereferencing @ptr.
 376  *
 377  * Returns zero on success, or -EFAULT on error.
 378  */
 379 #define put_user(x, ptr)                                        \
 380 ({                                                              \
 381         __typeof__(*(ptr)) __user *__p = (ptr);                 \
 382         might_fault();                                          \
 383         access_ok(__p, sizeof(*__p)) ?          \
 384                 __put_user((x), __p) :                          \
 385                 -EFAULT;                                        \
 386 })
 387
 388 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 389
 390 extern long __must_check strlen_user(const char __user *str);
 391 extern long __must_check strnlen_user(const char __user *str, long n);
 392
 393 extern
 394 unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 395
 396 static inline
 397 unsigned long __must_check clear_user(void __user *to, unsigned long n)
 398 {
 399         might_fault();
 400         return access_ok(to, n) ?
 401                 __clear_user(to, n) : n;
 402 }
 403
 404 /*
 405  * Atomic compare-and-exchange, but with a fixup for userspace faults.  Faults
 406  * will set "err" to -EFAULT, while successful accesses return the previous
 407  * value.
 408  */
 409 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb)      \
 410 ({                                                              \
 411         __typeof__(ptr) __ptr = (ptr);                          \
 412         __typeof__(*(ptr)) __old = (old);                       \
 413         __typeof__(*(ptr)) __new = (new);                       \
 414         __typeof__(*(ptr)) __ret;                               \
 415         __typeof__(err) __err = 0;                              \
 416         register unsigned int __rc;                             \
 417         __enable_user_access();                                 \
 418         switch (size) {                                         \
 419         case 4:                                                 \
 420                 __asm__ __volatile__ (                          \
 421                 "0:\n"                                          \
 422                 "       lr.w" #scb " %[ret], %[ptr]\n"          \
 423                 "       bne          %[ret], %z[old], 1f\n"     \
 424                 "       sc.w" #lrb " %[rc], %z[new], %[ptr]\n"  \
 425                 "       bnez         %[rc], 0b\n"               \
 426                 "1:\n"                                          \
 427                 ".section .fixup,\"ax\"\n"                      \
 428                 ".balign 4\n"                                   \
 429                 "2:\n"                                          \
 430                 "       li %[err], %[efault]\n"                 \
 431                 "       jump 1b, %[rc]\n"                       \
 432                 ".previous\n"                                   \
 433                 ".section __ex_table,\"a\"\n"                   \
 434                 ".balign " RISCV_SZPTR "\n"                     \
 435                 "       " RISCV_PTR " 1b, 2b\n"                 \
 436                 ".previous\n"                                   \
 437                         : [ret] "=&r" (__ret),                  \
 438                           [rc]  "=&r" (__rc),                   \
 439                           [ptr] "+A" (*__ptr),                  \
 440                           [err] "=&r" (__err)                   \
 441                         : [old] "rJ" (__old),                   \
 442                           [new] "rJ" (__new),                   \
 443                           [efault] "i" (-EFAULT));              \
 444                 break;                                          \
 445         case 8:                                                 \
 446                 __asm__ __volatile__ (                          \
 447                 "0:\n"                                          \
 448                 "       lr.d" #scb " %[ret], %[ptr]\n"          \
 449                 "       bne          %[ret], %z[old], 1f\n"     \
 450                 "       sc.d" #lrb " %[rc], %z[new], %[ptr]\n"  \
 451                 "       bnez         %[rc], 0b\n"               \
 452                 "1:\n"                                          \
 453                 ".section .fixup,\"ax\"\n"                      \
 454                 ".balign 4\n"                                   \
 455                 "2:\n"                                          \
 456                 "       li %[err], %[efault]\n"                 \
 457                 "       jump 1b, %[rc]\n"                       \
 458                 ".previous\n"                                   \
 459                 ".section __ex_table,\"a\"\n"                   \
 460                 ".balign " RISCV_SZPTR "\n"                     \
 461                 "       " RISCV_PTR " 1b, 2b\n"                 \
 462                 ".previous\n"                                   \
 463                         : [ret] "=&r" (__ret),                  \
 464                           [rc]  "=&r" (__rc),                   \
 465                           [ptr] "+A" (*__ptr),                  \
 466                           [err] "=&r" (__err)                   \
 467                         : [old] "rJ" (__old),                   \
 468                           [new] "rJ" (__new),                   \
 469                           [efault] "i" (-EFAULT));              \
 470                 break;                                          \
 471         default:                                                \
 472                 BUILD_BUG();                                    \
 473         }                                                       \
 474         __disable_user_access();                                \
 475         (err) = __err;                                          \
 476         __ret;                                                  \
 477 })
 478
 479 #else /* CONFIG_MMU */
 480 #include <asm-generic/uaccess.h>
 481 #endif /* CONFIG_MMU */
 482 #endif /* _ASM_RISCV_UACCESS_H */