arch/arm/include/asm/uaccess.h

   1 /*
   2  *  arch/arm/include/asm/uaccess.h
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #ifndef _ASMARM_UACCESS_H
   9 #define _ASMARM_UACCESS_H
  10
  11 /*
  12  * User space memory access functions
  13  */
  14 #include <linux/string.h>
  15 #include <asm/memory.h>
  16 #include <asm/domain.h>
  17 #include <asm/unified.h>
  18 #include <asm/compiler.h>
  19
  20 #include <asm/extable.h>
  21
  22 /*
  23  * These two functions allow hooking accesses to userspace to increase
  24  * system integrity by ensuring that the kernel can not inadvertantly
  25  * perform such accesses (eg, via list poison values) which could then
  26  * be exploited for priviledge escalation.
  27  */
  28 static inline unsigned int uaccess_save_and_enable(void)
  29 {
  30 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  31         unsigned int old_domain = get_domain();
  32
  33         /* Set the current domain access to permit user accesses */
  34         set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
  35                    domain_val(DOMAIN_USER, DOMAIN_CLIENT));
  36
  37         return old_domain;
  38 #else
  39         return 0;
  40 #endif
  41 }
  42
  43 static inline void uaccess_restore(unsigned int flags)
  44 {
  45 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  46         /* Restore the user access mask */
  47         set_domain(flags);
  48 #endif
  49 }
  50
  51 /*
  52  * These two are intentionally not defined anywhere - if the kernel
  53  * code generates any references to them, that's a bug.
  54  */
  55 extern int __get_user_bad(void);
  56 extern int __put_user_bad(void);
  57
  58 /*
  59  * Note that this is actually 0x1,0000,0000
  60  */
  61 #define KERNEL_DS       0x00000000
  62
  63 #ifdef CONFIG_MMU
  64
  65 #define USER_DS         TASK_SIZE
  66 #define get_fs()        (current_thread_info()->addr_limit)
  67
  68 static inline void set_fs(mm_segment_t fs)
  69 {
  70         current_thread_info()->addr_limit = fs;
  71
  72         /*
  73          * Prevent a mispredicted conditional call to set_fs from forwarding
  74          * the wrong address limit to access_ok under speculation.
  75          */
  76         dsb(nsh);
  77         isb();
  78
  79         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
  80 }
  81
  82 #define segment_eq(a, b)        ((a) == (b))
  83
  84 /* We use 33-bit arithmetic here... */
  85 #define __range_ok(addr, size) ({ \
  86         unsigned long flag, roksum; \
  87         __chk_user_ptr(addr);   \
  88         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
  89                 : "=&r" (flag), "=&r" (roksum) \
  90                 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
  91                 : "cc"); \
  92         flag; })
  93
  94 /*
  95  * This is a type: either unsigned long, if the argument fits into
  96  * that type, or otherwise unsigned long long.
  97  */
  98 #define __inttype(x) \
  99         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 100
 101 /*
 102  * Sanitise a uaccess pointer such that it becomes NULL if addr+size
 103  * is above the current addr_limit.
 104  */
 105 #define uaccess_mask_range_ptr(ptr, size)                       \
 106         ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
 107 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
 108                                                     size_t size)
 109 {
 110         void __user *safe_ptr = (void __user *)ptr;
 111         unsigned long tmp;
 112
 113         asm volatile(
 114         "       sub     %1, %3, #1\n"
 115         "       subs    %1, %1, %0\n"
 116         "       addhs   %1, %1, #1\n"
 117         "       subhss  %1, %1, %2\n"
 118         "       movlo   %0, #0\n"
 119         : "+r" (safe_ptr), "=&r" (tmp)
 120         : "r" (size), "r" (current_thread_info()->addr_limit)
 121         : "cc");
 122
 123         csdb();
 124         return safe_ptr;
 125 }
 126
 127 /*
 128  * Single-value transfer routines.  They automatically use the right
 129  * size if we just have the right pointer type.  Note that the functions
 130  * which read from user space (*get_*) need to take care not to leak
 131  * kernel data even if the calling code is buggy and fails to check
 132  * the return value.  This means zeroing out the destination variable
 133  * or buffer on error.  Normally this is done out of line by the
 134  * fixup code, but there are a few places where it intrudes on the
 135  * main code path.  When we only write to user space, there is no
 136  * problem.
 137  */
 138 extern int __get_user_1(void *);
 139 extern int __get_user_2(void *);
 140 extern int __get_user_4(void *);
 141 extern int __get_user_32t_8(void *);
 142 extern int __get_user_8(void *);
 143 extern int __get_user_64t_1(void *);
 144 extern int __get_user_64t_2(void *);
 145 extern int __get_user_64t_4(void *);
 146
 147 #define __GUP_CLOBBER_1 "lr", "cc"
 148 #ifdef CONFIG_CPU_USE_DOMAINS
 149 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
 150 #else
 151 #define __GUP_CLOBBER_2 "lr", "cc"
 152 #endif
 153 #define __GUP_CLOBBER_4 "lr", "cc"
 154 #define __GUP_CLOBBER_32t_8 "lr", "cc"
 155 #define __GUP_CLOBBER_8 "lr", "cc"
 156
 157 #define __get_user_x(__r2, __p, __e, __l, __s)                          \
 158            __asm__ __volatile__ (                                       \
 159                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 160                 __asmeq("%3", "r1")                                     \
 161                 "bl     __get_user_" #__s                               \
 162                 : "=&r" (__e), "=r" (__r2)                              \
 163                 : "0" (__p), "r" (__l)                                  \
 164                 : __GUP_CLOBBER_##__s)
 165
 166 /* narrowing a double-word get into a single 32bit word register: */
 167 #ifdef __ARMEB__
 168 #define __get_user_x_32t(__r2, __p, __e, __l, __s)                      \
 169         __get_user_x(__r2, __p, __e, __l, 32t_8)
 170 #else
 171 #define __get_user_x_32t __get_user_x
 172 #endif
 173
 174 /*
 175  * storing result into proper least significant word of 64bit target var,
 176  * different only for big endian case where 64 bit __r2 lsw is r3:
 177  */
 178 #ifdef __ARMEB__
 179 #define __get_user_x_64t(__r2, __p, __e, __l, __s)                      \
 180            __asm__ __volatile__ (                                       \
 181                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 182                 __asmeq("%3", "r1")                                     \
 183                 "bl     __get_user_64t_" #__s                           \
 184                 : "=&r" (__e), "=r" (__r2)                              \
 185                 : "0" (__p), "r" (__l)                                  \
 186                 : __GUP_CLOBBER_##__s)
 187 #else
 188 #define __get_user_x_64t __get_user_x
 189 #endif
 190
 191
 192 #define __get_user_check(x, p)                                          \
 193         ({                                                              \
 194                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 195                 register typeof(*(p)) __user *__p asm("r0") = (p);      \
 196                 register __inttype(x) __r2 asm("r2");                   \
 197                 register unsigned long __l asm("r1") = __limit;         \
 198                 register int __e asm("r0");                             \
 199                 unsigned int __ua_flags = uaccess_save_and_enable();    \
 200                 switch (sizeof(*(__p))) {                               \
 201                 case 1:                                                 \
 202                         if (sizeof((x)) >= 8)                           \
 203                                 __get_user_x_64t(__r2, __p, __e, __l, 1); \
 204                         else                                            \
 205                                 __get_user_x(__r2, __p, __e, __l, 1);   \
 206                         break;                                          \
 207                 case 2:                                                 \
 208                         if (sizeof((x)) >= 8)                           \
 209                                 __get_user_x_64t(__r2, __p, __e, __l, 2); \
 210                         else                                            \
 211                                 __get_user_x(__r2, __p, __e, __l, 2);   \
 212                         break;                                          \
 213                 case 4:                                                 \
 214                         if (sizeof((x)) >= 8)                           \
 215                                 __get_user_x_64t(__r2, __p, __e, __l, 4); \
 216                         else                                            \
 217                                 __get_user_x(__r2, __p, __e, __l, 4);   \
 218                         break;                                          \
 219                 case 8:                                                 \
 220                         if (sizeof((x)) < 8)                            \
 221                                 __get_user_x_32t(__r2, __p, __e, __l, 4); \
 222                         else                                            \
 223                                 __get_user_x(__r2, __p, __e, __l, 8);   \
 224                         break;                                          \
 225                 default: __e = __get_user_bad(); break;                 \
 226                 }                                                       \
 227                 uaccess_restore(__ua_flags);                            \
 228                 x = (typeof(*(p))) __r2;                                \
 229                 __e;                                                    \
 230         })
 231
 232 #define get_user(x, p)                                                  \
 233         ({                                                              \
 234                 might_fault();                                          \
 235                 __get_user_check(x, p);                                 \
 236          })
 237
 238 extern int __put_user_1(void *, unsigned int);
 239 extern int __put_user_2(void *, unsigned int);
 240 extern int __put_user_4(void *, unsigned int);
 241 extern int __put_user_8(void *, unsigned long long);
 242
 243 #define __put_user_check(__pu_val, __ptr, __err, __s)                   \
 244         ({                                                              \
 245                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 246                 register typeof(__pu_val) __r2 asm("r2") = __pu_val;    \
 247                 register const void __user *__p asm("r0") = __ptr;      \
 248                 register unsigned long __l asm("r1") = __limit;         \
 249                 register int __e asm("r0");                             \
 250                 __asm__ __volatile__ (                                  \
 251                         __asmeq("%0", "r0") __asmeq("%2", "r2")         \
 252                         __asmeq("%3", "r1")                             \
 253                         "bl     __put_user_" #__s                       \
 254                         : "=&r" (__e)                                   \
 255                         : "0" (__p), "r" (__r2), "r" (__l)              \
 256                         : "ip", "lr", "cc");                            \
 257                 __err = __e;                                            \
 258         })
 259
 260 #else /* CONFIG_MMU */
 261
 262 /*
 263  * uClinux has only one addr space, so has simplified address limits.
 264  */
 265 #define USER_DS                 KERNEL_DS
 266
 267 #define segment_eq(a, b)                (1)
 268 #define __addr_ok(addr)         ((void)(addr), 1)
 269 #define __range_ok(addr, size)  ((void)(addr), 0)
 270 #define get_fs()                (KERNEL_DS)
 271
 272 static inline void set_fs(mm_segment_t fs)
 273 {
 274 }
 275
 276 #define get_user(x, p)  __get_user(x, p)
 277 #define __put_user_check __put_user_nocheck
 278
 279 #endif /* CONFIG_MMU */
 280
 281 #define access_ok(addr, size)   (__range_ok(addr, size) == 0)
 282
 283 #define user_addr_max() \
 284         (uaccess_kernel() ? ~0UL : get_fs())
 285
 286 #ifdef CONFIG_CPU_SPECTRE
 287 /*
 288  * When mitigating Spectre variant 1, it is not worth fixing the non-
 289  * verifying accessors, because we need to add verification of the
 290  * address space there.  Force these to use the standard get_user()
 291  * version instead.
 292  */
 293 #define __get_user(x, ptr) get_user(x, ptr)
 294 #else
 295
 296 /*
 297  * The "__xxx" versions of the user access functions do not verify the
 298  * address space - it must have been done previously with a separate
 299  * "access_ok()" call.
 300  *
 301  * The "xxx_error" versions set the third argument to EFAULT if an
 302  * error occurs, and leave it unchanged on success.  Note that these
 303  * versions are void (ie, don't return a value as such).
 304  */
 305 #define __get_user(x, ptr)                                              \
 306 ({                                                                      \
 307         long __gu_err = 0;                                              \
 308         __get_user_err((x), (ptr), __gu_err);                           \
 309         __gu_err;                                                       \
 310 })
 311
 312 #define __get_user_err(x, ptr, err)                                     \
 313 do {                                                                    \
 314         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 315         unsigned long __gu_val;                                         \
 316         unsigned int __ua_flags;                                        \
 317         __chk_user_ptr(ptr);                                            \
 318         might_fault();                                                  \
 319         __ua_flags = uaccess_save_and_enable();                         \
 320         switch (sizeof(*(ptr))) {                                       \
 321         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err);  break;  \
 322         case 2: __get_user_asm_half(__gu_val, __gu_addr, err);  break;  \
 323         case 4: __get_user_asm_word(__gu_val, __gu_addr, err);  break;  \
 324         default: (__gu_val) = __get_user_bad();                         \
 325         }                                                               \
 326         uaccess_restore(__ua_flags);                                    \
 327         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 328 } while (0)
 329
 330 #define __get_user_asm(x, addr, err, instr)                     \
 331         __asm__ __volatile__(                                   \
 332         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 333         "2:\n"                                                  \
 334         "       .pushsection .text.fixup,\"ax\"\n"              \
 335         "       .align  2\n"                                    \
 336         "3:     mov     %0, %3\n"                               \
 337         "       mov     %1, #0\n"                               \
 338         "       b       2b\n"                                   \
 339         "       .popsection\n"                                  \
 340         "       .pushsection __ex_table,\"a\"\n"                \
 341         "       .align  3\n"                                    \
 342         "       .long   1b, 3b\n"                               \
 343         "       .popsection"                                    \
 344         : "+r" (err), "=&r" (x)                                 \
 345         : "r" (addr), "i" (-EFAULT)                             \
 346         : "cc")
 347
 348 #define __get_user_asm_byte(x, addr, err)                       \
 349         __get_user_asm(x, addr, err, ldrb)
 350
 351 #if __LINUX_ARM_ARCH__ >= 6
 352
 353 #define __get_user_asm_half(x, addr, err)                       \
 354         __get_user_asm(x, addr, err, ldrh)
 355
 356 #else
 357
 358 #ifndef __ARMEB__
 359 #define __get_user_asm_half(x, __gu_addr, err)                  \
 360 ({                                                              \
 361         unsigned long __b1, __b2;                               \
 362         __get_user_asm_byte(__b1, __gu_addr, err);              \
 363         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 364         (x) = __b1 | (__b2 << 8);                               \
 365 })
 366 #else
 367 #define __get_user_asm_half(x, __gu_addr, err)                  \
 368 ({                                                              \
 369         unsigned long __b1, __b2;                               \
 370         __get_user_asm_byte(__b1, __gu_addr, err);              \
 371         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 372         (x) = (__b1 << 8) | __b2;                               \
 373 })
 374 #endif
 375
 376 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 377
 378 #define __get_user_asm_word(x, addr, err)                       \
 379         __get_user_asm(x, addr, err, ldr)
 380 #endif
 381
 382
 383 #define __put_user_switch(x, ptr, __err, __fn)                          \
 384         do {                                                            \
 385                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 386                 __typeof__(*(ptr)) __pu_val = (x);                      \
 387                 unsigned int __ua_flags;                                \
 388                 might_fault();                                          \
 389                 __ua_flags = uaccess_save_and_enable();                 \
 390                 switch (sizeof(*(ptr))) {                               \
 391                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 392                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 393                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 394                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 395                 default: __err = __put_user_bad(); break;               \
 396                 }                                                       \
 397                 uaccess_restore(__ua_flags);                            \
 398         } while (0)
 399
 400 #define put_user(x, ptr)                                                \
 401 ({                                                                      \
 402         int __pu_err = 0;                                               \
 403         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 404         __pu_err;                                                       \
 405 })
 406
 407 #ifdef CONFIG_CPU_SPECTRE
 408 /*
 409  * When mitigating Spectre variant 1.1, all accessors need to include
 410  * verification of the address space.
 411  */
 412 #define __put_user(x, ptr) put_user(x, ptr)
 413
 414 #else
 415 #define __put_user(x, ptr)                                              \
 416 ({                                                                      \
 417         long __pu_err = 0;                                              \
 418         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 419         __pu_err;                                                       \
 420 })
 421
 422 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 423         do {                                                            \
 424                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 425                 __put_user_nocheck_##__size(x, __pu_addr, __err);       \
 426         } while (0)
 427
 428 #define __put_user_nocheck_1 __put_user_asm_byte
 429 #define __put_user_nocheck_2 __put_user_asm_half
 430 #define __put_user_nocheck_4 __put_user_asm_word
 431 #define __put_user_nocheck_8 __put_user_asm_dword
 432
 433 #define __put_user_asm(x, __pu_addr, err, instr)                \
 434         __asm__ __volatile__(                                   \
 435         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 436         "2:\n"                                                  \
 437         "       .pushsection .text.fixup,\"ax\"\n"              \
 438         "       .align  2\n"                                    \
 439         "3:     mov     %0, %3\n"                               \
 440         "       b       2b\n"                                   \
 441         "       .popsection\n"                                  \
 442         "       .pushsection __ex_table,\"a\"\n"                \
 443         "       .align  3\n"                                    \
 444         "       .long   1b, 3b\n"                               \
 445         "       .popsection"                                    \
 446         : "+r" (err)                                            \
 447         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 448         : "cc")
 449
 450 #define __put_user_asm_byte(x, __pu_addr, err)                  \
 451         __put_user_asm(x, __pu_addr, err, strb)
 452
 453 #if __LINUX_ARM_ARCH__ >= 6
 454
 455 #define __put_user_asm_half(x, __pu_addr, err)                  \
 456         __put_user_asm(x, __pu_addr, err, strh)
 457
 458 #else
 459
 460 #ifndef __ARMEB__
 461 #define __put_user_asm_half(x, __pu_addr, err)                  \
 462 ({                                                              \
 463         unsigned long __temp = (__force unsigned long)(x);      \
 464         __put_user_asm_byte(__temp, __pu_addr, err);            \
 465         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 466 })
 467 #else
 468 #define __put_user_asm_half(x, __pu_addr, err)                  \
 469 ({                                                              \
 470         unsigned long __temp = (__force unsigned long)(x);      \
 471         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 472         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 473 })
 474 #endif
 475
 476 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 477
 478 #define __put_user_asm_word(x, __pu_addr, err)                  \
 479         __put_user_asm(x, __pu_addr, err, str)
 480
 481 #ifndef __ARMEB__
 482 #define __reg_oper0     "%R2"
 483 #define __reg_oper1     "%Q2"
 484 #else
 485 #define __reg_oper0     "%Q2"
 486 #define __reg_oper1     "%R2"
 487 #endif
 488
 489 #define __put_user_asm_dword(x, __pu_addr, err)                 \
 490         __asm__ __volatile__(                                   \
 491  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 492  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 493  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 494  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 495         "3:\n"                                                  \
 496         "       .pushsection .text.fixup,\"ax\"\n"              \
 497         "       .align  2\n"                                    \
 498         "4:     mov     %0, %3\n"                               \
 499         "       b       3b\n"                                   \
 500         "       .popsection\n"                                  \
 501         "       .pushsection __ex_table,\"a\"\n"                \
 502         "       .align  3\n"                                    \
 503         "       .long   1b, 4b\n"                               \
 504         "       .long   2b, 4b\n"                               \
 505         "       .popsection"                                    \
 506         : "+r" (err), "+r" (__pu_addr)                          \
 507         : "r" (x), "i" (-EFAULT)                                \
 508         : "cc")
 509
 510 #endif /* !CONFIG_CPU_SPECTRE */
 511
 512 #ifdef CONFIG_MMU
 513 extern unsigned long __must_check
 514 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 515
 516 static inline unsigned long __must_check
 517 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 518 {
 519         unsigned int __ua_flags;
 520
 521         __ua_flags = uaccess_save_and_enable();
 522         n = arm_copy_from_user(to, from, n);
 523         uaccess_restore(__ua_flags);
 524         return n;
 525 }
 526
 527 extern unsigned long __must_check
 528 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 529 extern unsigned long __must_check
 530 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 531
 532 static inline unsigned long __must_check
 533 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 534 {
 535 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 536         unsigned int __ua_flags;
 537         __ua_flags = uaccess_save_and_enable();
 538         n = arm_copy_to_user(to, from, n);
 539         uaccess_restore(__ua_flags);
 540         return n;
 541 #else
 542         return arm_copy_to_user(to, from, n);
 543 #endif
 544 }
 545
 546 extern unsigned long __must_check
 547 arm_clear_user(void __user *addr, unsigned long n);
 548 extern unsigned long __must_check
 549 __clear_user_std(void __user *addr, unsigned long n);
 550
 551 static inline unsigned long __must_check
 552 __clear_user(void __user *addr, unsigned long n)
 553 {
 554         unsigned int __ua_flags = uaccess_save_and_enable();
 555         n = arm_clear_user(addr, n);
 556         uaccess_restore(__ua_flags);
 557         return n;
 558 }
 559
 560 #else
 561 static inline unsigned long
 562 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 563 {
 564         memcpy(to, (const void __force *)from, n);
 565         return 0;
 566 }
 567 static inline unsigned long
 568 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 569 {
 570         memcpy((void __force *)to, from, n);
 571         return 0;
 572 }
 573 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 574 #endif
 575 #define INLINE_COPY_TO_USER
 576 #define INLINE_COPY_FROM_USER
 577
 578 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 579 {
 580         if (access_ok(to, n))
 581                 n = __clear_user(to, n);
 582         return n;
 583 }
 584
 585 /* These are from lib/ code, and use __get_user() and friends */
 586 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 587
 588 extern __must_check long strnlen_user(const char __user *str, long n);
 589
 590 #endif /* _ASMARM_UACCESS_H */