arch/arm/include/asm/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  *  arch/arm/include/asm/uaccess.h
   4  */
   5 #ifndef _ASMARM_UACCESS_H
   6 #define _ASMARM_UACCESS_H
   7
   8 /*
   9  * User space memory access functions
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <asm/page.h>
  14 #include <asm/domain.h>
  15 #include <asm/unaligned.h>
  16 #include <asm/unified.h>
  17 #include <asm/compiler.h>
  18
  19 #include <asm/extable.h>
  20
  21 /*
  22  * These two functions allow hooking accesses to userspace to increase
  23  * system integrity by ensuring that the kernel can not inadvertantly
  24  * perform such accesses (eg, via list poison values) which could then
  25  * be exploited for priviledge escalation.
  26  */
  27 static __always_inline unsigned int uaccess_save_and_enable(void)
  28 {
  29 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  30         unsigned int old_domain = get_domain();
  31
  32         /* Set the current domain access to permit user accesses */
  33         set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
  34                    domain_val(DOMAIN_USER, DOMAIN_CLIENT));
  35
  36         return old_domain;
  37 #else
  38         return 0;
  39 #endif
  40 }
  41
  42 static __always_inline void uaccess_restore(unsigned int flags)
  43 {
  44 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  45         /* Restore the user access mask */
  46         set_domain(flags);
  47 #endif
  48 }
  49
  50 /*
  51  * These two are intentionally not defined anywhere - if the kernel
  52  * code generates any references to them, that's a bug.
  53  */
  54 extern int __get_user_bad(void);
  55 extern int __put_user_bad(void);
  56
  57 #ifdef CONFIG_MMU
  58
  59 /*
  60  * This is a type: either unsigned long, if the argument fits into
  61  * that type, or otherwise unsigned long long.
  62  */
  63 #define __inttype(x) \
  64         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
  65
  66 /*
  67  * Sanitise a uaccess pointer such that it becomes NULL if addr+size
  68  * is above the current addr_limit.
  69  */
  70 #define uaccess_mask_range_ptr(ptr, size)                       \
  71         ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
  72 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
  73                                                     size_t size)
  74 {
  75         void __user *safe_ptr = (void __user *)ptr;
  76         unsigned long tmp;
  77
  78         asm volatile(
  79         "       .syntax unified\n"
  80         "       sub     %1, %3, #1\n"
  81         "       subs    %1, %1, %0\n"
  82         "       addhs   %1, %1, #1\n"
  83         "       subshs  %1, %1, %2\n"
  84         "       movlo   %0, #0\n"
  85         : "+r" (safe_ptr), "=&r" (tmp)
  86         : "r" (size), "r" (TASK_SIZE)
  87         : "cc");
  88
  89         csdb();
  90         return safe_ptr;
  91 }
  92
  93 /*
  94  * Single-value transfer routines.  They automatically use the right
  95  * size if we just have the right pointer type.  Note that the functions
  96  * which read from user space (*get_*) need to take care not to leak
  97  * kernel data even if the calling code is buggy and fails to check
  98  * the return value.  This means zeroing out the destination variable
  99  * or buffer on error.  Normally this is done out of line by the
 100  * fixup code, but there are a few places where it intrudes on the
 101  * main code path.  When we only write to user space, there is no
 102  * problem.
 103  */
 104 extern int __get_user_1(void *);
 105 extern int __get_user_2(void *);
 106 extern int __get_user_4(void *);
 107 extern int __get_user_32t_8(void *);
 108 extern int __get_user_8(void *);
 109 extern int __get_user_64t_1(void *);
 110 extern int __get_user_64t_2(void *);
 111 extern int __get_user_64t_4(void *);
 112
 113 #define __get_user_x(__r2, __p, __e, __l, __s)                          \
 114            __asm__ __volatile__ (                                       \
 115                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 116                 __asmeq("%3", "r1")                                     \
 117                 "bl     __get_user_" #__s                               \
 118                 : "=&r" (__e), "=r" (__r2)                              \
 119                 : "0" (__p), "r" (__l)                                  \
 120                 : "ip", "lr", "cc")
 121
 122 /* narrowing a double-word get into a single 32bit word register: */
 123 #ifdef __ARMEB__
 124 #define __get_user_x_32t(__r2, __p, __e, __l, __s)                      \
 125         __get_user_x(__r2, __p, __e, __l, 32t_8)
 126 #else
 127 #define __get_user_x_32t __get_user_x
 128 #endif
 129
 130 /*
 131  * storing result into proper least significant word of 64bit target var,
 132  * different only for big endian case where 64 bit __r2 lsw is r3:
 133  */
 134 #ifdef __ARMEB__
 135 #define __get_user_x_64t(__r2, __p, __e, __l, __s)                      \
 136            __asm__ __volatile__ (                                       \
 137                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 138                 __asmeq("%3", "r1")                                     \
 139                 "bl     __get_user_64t_" #__s                           \
 140                 : "=&r" (__e), "=r" (__r2)                              \
 141                 : "0" (__p), "r" (__l)                                  \
 142                 : "ip", "lr", "cc")
 143 #else
 144 #define __get_user_x_64t __get_user_x
 145 #endif
 146
 147
 148 #define __get_user_check(x, p)                                          \
 149         ({                                                              \
 150                 unsigned long __limit = TASK_SIZE - 1; \
 151                 register typeof(*(p)) __user *__p asm("r0") = (p);      \
 152                 register __inttype(x) __r2 asm("r2");                   \
 153                 register unsigned long __l asm("r1") = __limit;         \
 154                 register int __e asm("r0");                             \
 155                 unsigned int __ua_flags = uaccess_save_and_enable();    \
 156                 int __tmp_e;                                            \
 157                 switch (sizeof(*(__p))) {                               \
 158                 case 1:                                                 \
 159                         if (sizeof((x)) >= 8)                           \
 160                                 __get_user_x_64t(__r2, __p, __e, __l, 1); \
 161                         else                                            \
 162                                 __get_user_x(__r2, __p, __e, __l, 1);   \
 163                         break;                                          \
 164                 case 2:                                                 \
 165                         if (sizeof((x)) >= 8)                           \
 166                                 __get_user_x_64t(__r2, __p, __e, __l, 2); \
 167                         else                                            \
 168                                 __get_user_x(__r2, __p, __e, __l, 2);   \
 169                         break;                                          \
 170                 case 4:                                                 \
 171                         if (sizeof((x)) >= 8)                           \
 172                                 __get_user_x_64t(__r2, __p, __e, __l, 4); \
 173                         else                                            \
 174                                 __get_user_x(__r2, __p, __e, __l, 4);   \
 175                         break;                                          \
 176                 case 8:                                                 \
 177                         if (sizeof((x)) < 8)                            \
 178                                 __get_user_x_32t(__r2, __p, __e, __l, 4); \
 179                         else                                            \
 180                                 __get_user_x(__r2, __p, __e, __l, 8);   \
 181                         break;                                          \
 182                 default: __e = __get_user_bad(); break;                 \
 183                 }                                                       \
 184                 __tmp_e = __e;                                          \
 185                 uaccess_restore(__ua_flags);                            \
 186                 x = (typeof(*(p))) __r2;                                \
 187                 __tmp_e;                                                \
 188         })
 189
 190 #define get_user(x, p)                                                  \
 191         ({                                                              \
 192                 might_fault();                                          \
 193                 __get_user_check(x, p);                                 \
 194          })
 195
 196 extern int __put_user_1(void *, unsigned int);
 197 extern int __put_user_2(void *, unsigned int);
 198 extern int __put_user_4(void *, unsigned int);
 199 extern int __put_user_8(void *, unsigned long long);
 200
 201 #define __put_user_check(__pu_val, __ptr, __err, __s)                   \
 202         ({                                                              \
 203                 unsigned long __limit = TASK_SIZE - 1; \
 204                 register typeof(__pu_val) __r2 asm("r2") = __pu_val;    \
 205                 register const void __user *__p asm("r0") = __ptr;      \
 206                 register unsigned long __l asm("r1") = __limit;         \
 207                 register int __e asm("r0");                             \
 208                 __asm__ __volatile__ (                                  \
 209                         __asmeq("%0", "r0") __asmeq("%2", "r2")         \
 210                         __asmeq("%3", "r1")                             \
 211                         "bl     __put_user_" #__s                       \
 212                         : "=&r" (__e)                                   \
 213                         : "0" (__p), "r" (__r2), "r" (__l)              \
 214                         : "ip", "lr", "cc");                            \
 215                 __err = __e;                                            \
 216         })
 217
 218 #else /* CONFIG_MMU */
 219
 220 #define get_user(x, p)  __get_user(x, p)
 221 #define __put_user_check __put_user_nocheck
 222
 223 #endif /* CONFIG_MMU */
 224
 225 #include <asm-generic/access_ok.h>
 226
 227 #ifdef CONFIG_CPU_SPECTRE
 228 /*
 229  * When mitigating Spectre variant 1, it is not worth fixing the non-
 230  * verifying accessors, because we need to add verification of the
 231  * address space there.  Force these to use the standard get_user()
 232  * version instead.
 233  */
 234 #define __get_user(x, ptr) get_user(x, ptr)
 235 #else
 236
 237 /*
 238  * The "__xxx" versions of the user access functions do not verify the
 239  * address space - it must have been done previously with a separate
 240  * "access_ok()" call.
 241  *
 242  * The "xxx_error" versions set the third argument to EFAULT if an
 243  * error occurs, and leave it unchanged on success.  Note that these
 244  * versions are void (ie, don't return a value as such).
 245  */
 246 #define __get_user(x, ptr)                                              \
 247 ({                                                                      \
 248         long __gu_err = 0;                                              \
 249         __get_user_err((x), (ptr), __gu_err, TUSER());                  \
 250         __gu_err;                                                       \
 251 })
 252
 253 #define __get_user_err(x, ptr, err, __t)                                \
 254 do {                                                                    \
 255         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 256         unsigned long __gu_val;                                         \
 257         unsigned int __ua_flags;                                        \
 258         __chk_user_ptr(ptr);                                            \
 259         might_fault();                                                  \
 260         __ua_flags = uaccess_save_and_enable();                         \
 261         switch (sizeof(*(ptr))) {                                       \
 262         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break;      \
 263         case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break;      \
 264         case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break;      \
 265         default: (__gu_val) = __get_user_bad();                         \
 266         }                                                               \
 267         uaccess_restore(__ua_flags);                                    \
 268         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 269 } while (0)
 270 #endif
 271
 272 #define __get_user_asm(x, addr, err, instr)                     \
 273         __asm__ __volatile__(                                   \
 274         "1:     " instr " %1, [%2], #0\n"                       \
 275         "2:\n"                                                  \
 276         "       .pushsection .text.fixup,\"ax\"\n"              \
 277         "       .align  2\n"                                    \
 278         "3:     mov     %0, %3\n"                               \
 279         "       mov     %1, #0\n"                               \
 280         "       b       2b\n"                                   \
 281         "       .popsection\n"                                  \
 282         "       .pushsection __ex_table,\"a\"\n"                \
 283         "       .align  3\n"                                    \
 284         "       .long   1b, 3b\n"                               \
 285         "       .popsection"                                    \
 286         : "+r" (err), "=&r" (x)                                 \
 287         : "r" (addr), "i" (-EFAULT)                             \
 288         : "cc")
 289
 290 #define __get_user_asm_byte(x, addr, err, __t)                  \
 291         __get_user_asm(x, addr, err, "ldrb" __t)
 292
 293 #if __LINUX_ARM_ARCH__ >= 6
 294
 295 #define __get_user_asm_half(x, addr, err, __t)                  \
 296         __get_user_asm(x, addr, err, "ldrh" __t)
 297
 298 #else
 299
 300 #ifndef __ARMEB__
 301 #define __get_user_asm_half(x, __gu_addr, err, __t)             \
 302 ({                                                              \
 303         unsigned long __b1, __b2;                               \
 304         __get_user_asm_byte(__b1, __gu_addr, err, __t);         \
 305         __get_user_asm_byte(__b2, __gu_addr + 1, err, __t);     \
 306         (x) = __b1 | (__b2 << 8);                               \
 307 })
 308 #else
 309 #define __get_user_asm_half(x, __gu_addr, err, __t)             \
 310 ({                                                              \
 311         unsigned long __b1, __b2;                               \
 312         __get_user_asm_byte(__b1, __gu_addr, err, __t);         \
 313         __get_user_asm_byte(__b2, __gu_addr + 1, err, __t);     \
 314         (x) = (__b1 << 8) | __b2;                               \
 315 })
 316 #endif
 317
 318 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 319
 320 #define __get_user_asm_word(x, addr, err, __t)                  \
 321         __get_user_asm(x, addr, err, "ldr" __t)
 322
 323 #define __put_user_switch(x, ptr, __err, __fn)                          \
 324         do {                                                            \
 325                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 326                 __typeof__(*(ptr)) __pu_val = (x);                      \
 327                 unsigned int __ua_flags;                                \
 328                 might_fault();                                          \
 329                 __ua_flags = uaccess_save_and_enable();                 \
 330                 switch (sizeof(*(ptr))) {                               \
 331                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 332                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 333                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 334                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 335                 default: __err = __put_user_bad(); break;               \
 336                 }                                                       \
 337                 uaccess_restore(__ua_flags);                            \
 338         } while (0)
 339
 340 #define put_user(x, ptr)                                                \
 341 ({                                                                      \
 342         int __pu_err = 0;                                               \
 343         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 344         __pu_err;                                                       \
 345 })
 346
 347 #ifdef CONFIG_CPU_SPECTRE
 348 /*
 349  * When mitigating Spectre variant 1.1, all accessors need to include
 350  * verification of the address space.
 351  */
 352 #define __put_user(x, ptr) put_user(x, ptr)
 353
 354 #else
 355 #define __put_user(x, ptr)                                              \
 356 ({                                                                      \
 357         long __pu_err = 0;                                              \
 358         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 359         __pu_err;                                                       \
 360 })
 361
 362 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 363         do {                                                            \
 364                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 365                 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\
 366         } while (0)
 367
 368 #define __put_user_nocheck_1 __put_user_asm_byte
 369 #define __put_user_nocheck_2 __put_user_asm_half
 370 #define __put_user_nocheck_4 __put_user_asm_word
 371 #define __put_user_nocheck_8 __put_user_asm_dword
 372
 373 #endif /* !CONFIG_CPU_SPECTRE */
 374
 375 #define __put_user_asm(x, __pu_addr, err, instr)                \
 376         __asm__ __volatile__(                                   \
 377         "1:     " instr " %1, [%2], #0\n"               \
 378         "2:\n"                                                  \
 379         "       .pushsection .text.fixup,\"ax\"\n"              \
 380         "       .align  2\n"                                    \
 381         "3:     mov     %0, %3\n"                               \
 382         "       b       2b\n"                                   \
 383         "       .popsection\n"                                  \
 384         "       .pushsection __ex_table,\"a\"\n"                \
 385         "       .align  3\n"                                    \
 386         "       .long   1b, 3b\n"                               \
 387         "       .popsection"                                    \
 388         : "+r" (err)                                            \
 389         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 390         : "cc")
 391
 392 #define __put_user_asm_byte(x, __pu_addr, err, __t)             \
 393         __put_user_asm(x, __pu_addr, err, "strb" __t)
 394
 395 #if __LINUX_ARM_ARCH__ >= 6
 396
 397 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 398         __put_user_asm(x, __pu_addr, err, "strh" __t)
 399
 400 #else
 401
 402 #ifndef __ARMEB__
 403 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 404 ({                                                              \
 405         unsigned long __temp = (__force unsigned long)(x);      \
 406         __put_user_asm_byte(__temp, __pu_addr, err, __t);       \
 407         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\
 408 })
 409 #else
 410 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 411 ({                                                              \
 412         unsigned long __temp = (__force unsigned long)(x);      \
 413         __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t);  \
 414         __put_user_asm_byte(__temp, __pu_addr + 1, err, __t);   \
 415 })
 416 #endif
 417
 418 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 419
 420 #define __put_user_asm_word(x, __pu_addr, err, __t)             \
 421         __put_user_asm(x, __pu_addr, err, "str" __t)
 422
 423 #ifndef __ARMEB__
 424 #define __reg_oper0     "%R2"
 425 #define __reg_oper1     "%Q2"
 426 #else
 427 #define __reg_oper0     "%Q2"
 428 #define __reg_oper1     "%R2"
 429 #endif
 430
 431 #define __put_user_asm_dword(x, __pu_addr, err, __t)            \
 432         __asm__ __volatile__(                                   \
 433  ARM(   "1:     str" __t "      " __reg_oper1 ", [%1], #4\n"  ) \
 434  ARM(   "2:     str" __t "      " __reg_oper0 ", [%1]\n"      ) \
 435  THUMB( "1:     str" __t "      " __reg_oper1 ", [%1]\n"      ) \
 436  THUMB( "2:     str" __t "      " __reg_oper0 ", [%1, #4]\n"  ) \
 437         "3:\n"                                                  \
 438         "       .pushsection .text.fixup,\"ax\"\n"              \
 439         "       .align  2\n"                                    \
 440         "4:     mov     %0, %3\n"                               \
 441         "       b       3b\n"                                   \
 442         "       .popsection\n"                                  \
 443         "       .pushsection __ex_table,\"a\"\n"                \
 444         "       .align  3\n"                                    \
 445         "       .long   1b, 4b\n"                               \
 446         "       .long   2b, 4b\n"                               \
 447         "       .popsection"                                    \
 448         : "+r" (err), "+r" (__pu_addr)                          \
 449         : "r" (x), "i" (-EFAULT)                                \
 450         : "cc")
 451
 452 #define __get_kernel_nofault(dst, src, type, err_label)                 \
 453 do {                                                                    \
 454         const type *__pk_ptr = (src);                                   \
 455         unsigned long __src = (unsigned long)(__pk_ptr);                \
 456         type __val;                                                     \
 457         int __err = 0;                                                  \
 458         switch (sizeof(type)) {                                         \
 459         case 1: __get_user_asm_byte(__val, __src, __err, ""); break;    \
 460         case 2: __get_user_asm_half(__val, __src, __err, ""); break;    \
 461         case 4: __get_user_asm_word(__val, __src, __err, ""); break;    \
 462         case 8: {                                                       \
 463                 u32 *__v32 = (u32*)&__val;                              \
 464                 __get_user_asm_word(__v32[0], __src, __err, "");        \
 465                 if (__err)                                              \
 466                         break;                                          \
 467                 __get_user_asm_word(__v32[1], __src+4, __err, "");      \
 468                 break;                                                  \
 469         }                                                               \
 470         default: __err = __get_user_bad(); break;                       \
 471         }                                                               \
 472         if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))         \
 473                 put_unaligned(__val, (type *)(dst));                    \
 474         else                                                            \
 475                 *(type *)(dst) = __val; /* aligned by caller */         \
 476         if (__err)                                                      \
 477                 goto err_label;                                         \
 478 } while (0)
 479
 480 #define __put_kernel_nofault(dst, src, type, err_label)                 \
 481 do {                                                                    \
 482         const type *__pk_ptr = (dst);                                   \
 483         unsigned long __dst = (unsigned long)__pk_ptr;                  \
 484         int __err = 0;                                                  \
 485         type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \
 486                      ? get_unaligned((type *)(src))                     \
 487                      : *(type *)(src);  /* aligned by caller */         \
 488         switch (sizeof(type)) {                                         \
 489         case 1: __put_user_asm_byte(__val, __dst, __err, ""); break;    \
 490         case 2: __put_user_asm_half(__val, __dst, __err, ""); break;    \
 491         case 4: __put_user_asm_word(__val, __dst, __err, ""); break;    \
 492         case 8: __put_user_asm_dword(__val, __dst, __err, ""); break;   \
 493         default: __err = __put_user_bad(); break;                       \
 494         }                                                               \
 495         if (__err)                                                      \
 496                 goto err_label;                                         \
 497 } while (0)
 498
 499 #ifdef CONFIG_MMU
 500 extern unsigned long __must_check
 501 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 502
 503 static inline unsigned long __must_check
 504 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 505 {
 506         unsigned int __ua_flags;
 507
 508         __ua_flags = uaccess_save_and_enable();
 509         n = arm_copy_from_user(to, from, n);
 510         uaccess_restore(__ua_flags);
 511         return n;
 512 }
 513
 514 extern unsigned long __must_check
 515 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 516 extern unsigned long __must_check
 517 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 518
 519 static inline unsigned long __must_check
 520 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 521 {
 522 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 523         unsigned int __ua_flags;
 524         __ua_flags = uaccess_save_and_enable();
 525         n = arm_copy_to_user(to, from, n);
 526         uaccess_restore(__ua_flags);
 527         return n;
 528 #else
 529         return arm_copy_to_user(to, from, n);
 530 #endif
 531 }
 532
 533 extern unsigned long __must_check
 534 arm_clear_user(void __user *addr, unsigned long n);
 535 extern unsigned long __must_check
 536 __clear_user_std(void __user *addr, unsigned long n);
 537
 538 static inline unsigned long __must_check
 539 __clear_user(void __user *addr, unsigned long n)
 540 {
 541         unsigned int __ua_flags = uaccess_save_and_enable();
 542         n = arm_clear_user(addr, n);
 543         uaccess_restore(__ua_flags);
 544         return n;
 545 }
 546
 547 #else
 548 static inline unsigned long
 549 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 550 {
 551         memcpy(to, (const void __force *)from, n);
 552         return 0;
 553 }
 554 static inline unsigned long
 555 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 556 {
 557         memcpy((void __force *)to, from, n);
 558         return 0;
 559 }
 560 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 561 #endif
 562 #define INLINE_COPY_TO_USER
 563 #define INLINE_COPY_FROM_USER
 564
 565 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 566 {
 567         if (access_ok(to, n))
 568                 n = __clear_user(to, n);
 569         return n;
 570 }
 571
 572 /* These are from lib/ code, and use __get_user() and friends */
 573 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 574
 575 extern __must_check long strnlen_user(const char __user *str, long n);
 576
 577 #endif /* _ASMARM_UACCESS_H */