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/string.h>
  12 #include <asm/memory.h>
  13 #include <asm/domain.h>
  14 #include <asm/unified.h>
  15 #include <asm/compiler.h>
  16
  17 #include <asm/extable.h>
  18
  19 /*
  20  * These two functions allow hooking accesses to userspace to increase
  21  * system integrity by ensuring that the kernel can not inadvertantly
  22  * perform such accesses (eg, via list poison values) which could then
  23  * be exploited for priviledge escalation.
  24  */
  25 static __always_inline unsigned int uaccess_save_and_enable(void)
  26 {
  27 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  28         unsigned int old_domain = get_domain();
  29
  30         /* Set the current domain access to permit user accesses */
  31         set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
  32                    domain_val(DOMAIN_USER, DOMAIN_CLIENT));
  33
  34         return old_domain;
  35 #else
  36         return 0;
  37 #endif
  38 }
  39
  40 static __always_inline void uaccess_restore(unsigned int flags)
  41 {
  42 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  43         /* Restore the user access mask */
  44         set_domain(flags);
  45 #endif
  46 }
  47
  48 /*
  49  * These two are intentionally not defined anywhere - if the kernel
  50  * code generates any references to them, that's a bug.
  51  */
  52 extern int __get_user_bad(void);
  53 extern int __put_user_bad(void);
  54
  55 #ifdef CONFIG_MMU
  56
  57 /*
  58  * We use 33-bit arithmetic here.  Success returns zero, failure returns
  59  * addr_limit.  We take advantage that addr_limit will be zero for KERNEL_DS,
  60  * so this will always return success in that case.
  61  */
  62 #define __range_ok(addr, size) ({ \
  63         unsigned long flag, roksum; \
  64         __chk_user_ptr(addr);   \
  65         __asm__(".syntax unified\n" \
  66                 "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \
  67                 : "=&r" (flag), "=&r" (roksum) \
  68                 : "r" (addr), "Ir" (size), "0" (TASK_SIZE) \
  69                 : "cc"); \
  70         flag; })
  71
  72 /*
  73  * This is a type: either unsigned long, if the argument fits into
  74  * that type, or otherwise unsigned long long.
  75  */
  76 #define __inttype(x) \
  77         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
  78
  79 /*
  80  * Sanitise a uaccess pointer such that it becomes NULL if addr+size
  81  * is above the current addr_limit.
  82  */
  83 #define uaccess_mask_range_ptr(ptr, size)                       \
  84         ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
  85 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
  86                                                     size_t size)
  87 {
  88         void __user *safe_ptr = (void __user *)ptr;
  89         unsigned long tmp;
  90
  91         asm volatile(
  92         "       .syntax unified\n"
  93         "       sub     %1, %3, #1\n"
  94         "       subs    %1, %1, %0\n"
  95         "       addhs   %1, %1, #1\n"
  96         "       subshs  %1, %1, %2\n"
  97         "       movlo   %0, #0\n"
  98         : "+r" (safe_ptr), "=&r" (tmp)
  99         : "r" (size), "r" (TASK_SIZE)
 100         : "cc");
 101
 102         csdb();
 103         return safe_ptr;
 104 }
 105
 106 /*
 107  * Single-value transfer routines.  They automatically use the right
 108  * size if we just have the right pointer type.  Note that the functions
 109  * which read from user space (*get_*) need to take care not to leak
 110  * kernel data even if the calling code is buggy and fails to check
 111  * the return value.  This means zeroing out the destination variable
 112  * or buffer on error.  Normally this is done out of line by the
 113  * fixup code, but there are a few places where it intrudes on the
 114  * main code path.  When we only write to user space, there is no
 115  * problem.
 116  */
 117 extern int __get_user_1(void *);
 118 extern int __get_user_2(void *);
 119 extern int __get_user_4(void *);
 120 extern int __get_user_32t_8(void *);
 121 extern int __get_user_8(void *);
 122 extern int __get_user_64t_1(void *);
 123 extern int __get_user_64t_2(void *);
 124 extern int __get_user_64t_4(void *);
 125
 126 #define __GUP_CLOBBER_1 "lr", "cc"
 127 #ifdef CONFIG_CPU_USE_DOMAINS
 128 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
 129 #else
 130 #define __GUP_CLOBBER_2 "lr", "cc"
 131 #endif
 132 #define __GUP_CLOBBER_4 "lr", "cc"
 133 #define __GUP_CLOBBER_32t_8 "lr", "cc"
 134 #define __GUP_CLOBBER_8 "lr", "cc"
 135
 136 #define __get_user_x(__r2, __p, __e, __l, __s)                          \
 137            __asm__ __volatile__ (                                       \
 138                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 139                 __asmeq("%3", "r1")                                     \
 140                 "bl     __get_user_" #__s                               \
 141                 : "=&r" (__e), "=r" (__r2)                              \
 142                 : "0" (__p), "r" (__l)                                  \
 143                 : __GUP_CLOBBER_##__s)
 144
 145 /* narrowing a double-word get into a single 32bit word register: */
 146 #ifdef __ARMEB__
 147 #define __get_user_x_32t(__r2, __p, __e, __l, __s)                      \
 148         __get_user_x(__r2, __p, __e, __l, 32t_8)
 149 #else
 150 #define __get_user_x_32t __get_user_x
 151 #endif
 152
 153 /*
 154  * storing result into proper least significant word of 64bit target var,
 155  * different only for big endian case where 64 bit __r2 lsw is r3:
 156  */
 157 #ifdef __ARMEB__
 158 #define __get_user_x_64t(__r2, __p, __e, __l, __s)                      \
 159            __asm__ __volatile__ (                                       \
 160                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 161                 __asmeq("%3", "r1")                                     \
 162                 "bl     __get_user_64t_" #__s                           \
 163                 : "=&r" (__e), "=r" (__r2)                              \
 164                 : "0" (__p), "r" (__l)                                  \
 165                 : __GUP_CLOBBER_##__s)
 166 #else
 167 #define __get_user_x_64t __get_user_x
 168 #endif
 169
 170
 171 #define __get_user_check(x, p)                                          \
 172         ({                                                              \
 173                 unsigned long __limit = TASK_SIZE - 1; \
 174                 register typeof(*(p)) __user *__p asm("r0") = (p);      \
 175                 register __inttype(x) __r2 asm("r2");                   \
 176                 register unsigned long __l asm("r1") = __limit;         \
 177                 register int __e asm("r0");                             \
 178                 unsigned int __ua_flags = uaccess_save_and_enable();    \
 179                 switch (sizeof(*(__p))) {                               \
 180                 case 1:                                                 \
 181                         if (sizeof((x)) >= 8)                           \
 182                                 __get_user_x_64t(__r2, __p, __e, __l, 1); \
 183                         else                                            \
 184                                 __get_user_x(__r2, __p, __e, __l, 1);   \
 185                         break;                                          \
 186                 case 2:                                                 \
 187                         if (sizeof((x)) >= 8)                           \
 188                                 __get_user_x_64t(__r2, __p, __e, __l, 2); \
 189                         else                                            \
 190                                 __get_user_x(__r2, __p, __e, __l, 2);   \
 191                         break;                                          \
 192                 case 4:                                                 \
 193                         if (sizeof((x)) >= 8)                           \
 194                                 __get_user_x_64t(__r2, __p, __e, __l, 4); \
 195                         else                                            \
 196                                 __get_user_x(__r2, __p, __e, __l, 4);   \
 197                         break;                                          \
 198                 case 8:                                                 \
 199                         if (sizeof((x)) < 8)                            \
 200                                 __get_user_x_32t(__r2, __p, __e, __l, 4); \
 201                         else                                            \
 202                                 __get_user_x(__r2, __p, __e, __l, 8);   \
 203                         break;                                          \
 204                 default: __e = __get_user_bad(); break;                 \
 205                 }                                                       \
 206                 uaccess_restore(__ua_flags);                            \
 207                 x = (typeof(*(p))) __r2;                                \
 208                 __e;                                                    \
 209         })
 210
 211 #define get_user(x, p)                                                  \
 212         ({                                                              \
 213                 might_fault();                                          \
 214                 __get_user_check(x, p);                                 \
 215          })
 216
 217 extern int __put_user_1(void *, unsigned int);
 218 extern int __put_user_2(void *, unsigned int);
 219 extern int __put_user_4(void *, unsigned int);
 220 extern int __put_user_8(void *, unsigned long long);
 221
 222 #define __put_user_check(__pu_val, __ptr, __err, __s)                   \
 223         ({                                                              \
 224                 unsigned long __limit = TASK_SIZE - 1; \
 225                 register typeof(__pu_val) __r2 asm("r2") = __pu_val;    \
 226                 register const void __user *__p asm("r0") = __ptr;      \
 227                 register unsigned long __l asm("r1") = __limit;         \
 228                 register int __e asm("r0");                             \
 229                 __asm__ __volatile__ (                                  \
 230                         __asmeq("%0", "r0") __asmeq("%2", "r2")         \
 231                         __asmeq("%3", "r1")                             \
 232                         "bl     __put_user_" #__s                       \
 233                         : "=&r" (__e)                                   \
 234                         : "0" (__p), "r" (__r2), "r" (__l)              \
 235                         : "ip", "lr", "cc");                            \
 236                 __err = __e;                                            \
 237         })
 238
 239 #else /* CONFIG_MMU */
 240
 241 #define __addr_ok(addr)         ((void)(addr), 1)
 242 #define __range_ok(addr, size)  ((void)(addr), 0)
 243
 244 #define get_user(x, p)  __get_user(x, p)
 245 #define __put_user_check __put_user_nocheck
 246
 247 #endif /* CONFIG_MMU */
 248
 249 #define access_ok(addr, size)   (__range_ok(addr, size) == 0)
 250
 251 #ifdef CONFIG_CPU_SPECTRE
 252 /*
 253  * When mitigating Spectre variant 1, it is not worth fixing the non-
 254  * verifying accessors, because we need to add verification of the
 255  * address space there.  Force these to use the standard get_user()
 256  * version instead.
 257  */
 258 #define __get_user(x, ptr) get_user(x, ptr)
 259 #else
 260
 261 /*
 262  * The "__xxx" versions of the user access functions do not verify the
 263  * address space - it must have been done previously with a separate
 264  * "access_ok()" call.
 265  *
 266  * The "xxx_error" versions set the third argument to EFAULT if an
 267  * error occurs, and leave it unchanged on success.  Note that these
 268  * versions are void (ie, don't return a value as such).
 269  */
 270 #define __get_user(x, ptr)                                              \
 271 ({                                                                      \
 272         long __gu_err = 0;                                              \
 273         __get_user_err((x), (ptr), __gu_err, TUSER());                  \
 274         __gu_err;                                                       \
 275 })
 276
 277 #define __get_user_err(x, ptr, err, __t)                                \
 278 do {                                                                    \
 279         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 280         unsigned long __gu_val;                                         \
 281         unsigned int __ua_flags;                                        \
 282         __chk_user_ptr(ptr);                                            \
 283         might_fault();                                                  \
 284         __ua_flags = uaccess_save_and_enable();                         \
 285         switch (sizeof(*(ptr))) {                                       \
 286         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break;      \
 287         case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break;      \
 288         case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break;      \
 289         default: (__gu_val) = __get_user_bad();                         \
 290         }                                                               \
 291         uaccess_restore(__ua_flags);                                    \
 292         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 293 } while (0)
 294 #endif
 295
 296 #define __get_user_asm(x, addr, err, instr)                     \
 297         __asm__ __volatile__(                                   \
 298         "1:     " instr " %1, [%2], #0\n"                       \
 299         "2:\n"                                                  \
 300         "       .pushsection .text.fixup,\"ax\"\n"              \
 301         "       .align  2\n"                                    \
 302         "3:     mov     %0, %3\n"                               \
 303         "       mov     %1, #0\n"                               \
 304         "       b       2b\n"                                   \
 305         "       .popsection\n"                                  \
 306         "       .pushsection __ex_table,\"a\"\n"                \
 307         "       .align  3\n"                                    \
 308         "       .long   1b, 3b\n"                               \
 309         "       .popsection"                                    \
 310         : "+r" (err), "=&r" (x)                                 \
 311         : "r" (addr), "i" (-EFAULT)                             \
 312         : "cc")
 313
 314 #define __get_user_asm_byte(x, addr, err, __t)                  \
 315         __get_user_asm(x, addr, err, "ldrb" __t)
 316
 317 #if __LINUX_ARM_ARCH__ >= 6
 318
 319 #define __get_user_asm_half(x, addr, err, __t)                  \
 320         __get_user_asm(x, addr, err, "ldrh" __t)
 321
 322 #else
 323
 324 #ifndef __ARMEB__
 325 #define __get_user_asm_half(x, __gu_addr, err, __t)             \
 326 ({                                                              \
 327         unsigned long __b1, __b2;                               \
 328         __get_user_asm_byte(__b1, __gu_addr, err, __t);         \
 329         __get_user_asm_byte(__b2, __gu_addr + 1, err, __t);     \
 330         (x) = __b1 | (__b2 << 8);                               \
 331 })
 332 #else
 333 #define __get_user_asm_half(x, __gu_addr, err, __t)             \
 334 ({                                                              \
 335         unsigned long __b1, __b2;                               \
 336         __get_user_asm_byte(__b1, __gu_addr, err, __t);         \
 337         __get_user_asm_byte(__b2, __gu_addr + 1, err, __t);     \
 338         (x) = (__b1 << 8) | __b2;                               \
 339 })
 340 #endif
 341
 342 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 343
 344 #define __get_user_asm_word(x, addr, err, __t)                  \
 345         __get_user_asm(x, addr, err, "ldr" __t)
 346
 347 #define __put_user_switch(x, ptr, __err, __fn)                          \
 348         do {                                                            \
 349                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 350                 __typeof__(*(ptr)) __pu_val = (x);                      \
 351                 unsigned int __ua_flags;                                \
 352                 might_fault();                                          \
 353                 __ua_flags = uaccess_save_and_enable();                 \
 354                 switch (sizeof(*(ptr))) {                               \
 355                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 356                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 357                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 358                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 359                 default: __err = __put_user_bad(); break;               \
 360                 }                                                       \
 361                 uaccess_restore(__ua_flags);                            \
 362         } while (0)
 363
 364 #define put_user(x, ptr)                                                \
 365 ({                                                                      \
 366         int __pu_err = 0;                                               \
 367         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 368         __pu_err;                                                       \
 369 })
 370
 371 #ifdef CONFIG_CPU_SPECTRE
 372 /*
 373  * When mitigating Spectre variant 1.1, all accessors need to include
 374  * verification of the address space.
 375  */
 376 #define __put_user(x, ptr) put_user(x, ptr)
 377
 378 #else
 379 #define __put_user(x, ptr)                                              \
 380 ({                                                                      \
 381         long __pu_err = 0;                                              \
 382         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 383         __pu_err;                                                       \
 384 })
 385
 386 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 387         do {                                                            \
 388                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 389                 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\
 390         } while (0)
 391
 392 #define __put_user_nocheck_1 __put_user_asm_byte
 393 #define __put_user_nocheck_2 __put_user_asm_half
 394 #define __put_user_nocheck_4 __put_user_asm_word
 395 #define __put_user_nocheck_8 __put_user_asm_dword
 396
 397 #endif /* !CONFIG_CPU_SPECTRE */
 398
 399 #define __put_user_asm(x, __pu_addr, err, instr)                \
 400         __asm__ __volatile__(                                   \
 401         "1:     " instr " %1, [%2], #0\n"               \
 402         "2:\n"                                                  \
 403         "       .pushsection .text.fixup,\"ax\"\n"              \
 404         "       .align  2\n"                                    \
 405         "3:     mov     %0, %3\n"                               \
 406         "       b       2b\n"                                   \
 407         "       .popsection\n"                                  \
 408         "       .pushsection __ex_table,\"a\"\n"                \
 409         "       .align  3\n"                                    \
 410         "       .long   1b, 3b\n"                               \
 411         "       .popsection"                                    \
 412         : "+r" (err)                                            \
 413         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 414         : "cc")
 415
 416 #define __put_user_asm_byte(x, __pu_addr, err, __t)             \
 417         __put_user_asm(x, __pu_addr, err, "strb" __t)
 418
 419 #if __LINUX_ARM_ARCH__ >= 6
 420
 421 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 422         __put_user_asm(x, __pu_addr, err, "strh" __t)
 423
 424 #else
 425
 426 #ifndef __ARMEB__
 427 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 428 ({                                                              \
 429         unsigned long __temp = (__force unsigned long)(x);      \
 430         __put_user_asm_byte(__temp, __pu_addr, err, __t);       \
 431         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\
 432 })
 433 #else
 434 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 435 ({                                                              \
 436         unsigned long __temp = (__force unsigned long)(x);      \
 437         __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t);  \
 438         __put_user_asm_byte(__temp, __pu_addr + 1, err, __t);   \
 439 })
 440 #endif
 441
 442 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 443
 444 #define __put_user_asm_word(x, __pu_addr, err, __t)             \
 445         __put_user_asm(x, __pu_addr, err, "str" __t)
 446
 447 #ifndef __ARMEB__
 448 #define __reg_oper0     "%R2"
 449 #define __reg_oper1     "%Q2"
 450 #else
 451 #define __reg_oper0     "%Q2"
 452 #define __reg_oper1     "%R2"
 453 #endif
 454
 455 #define __put_user_asm_dword(x, __pu_addr, err, __t)            \
 456         __asm__ __volatile__(                                   \
 457  ARM(   "1:     str" __t "      " __reg_oper1 ", [%1], #4\n"  ) \
 458  ARM(   "2:     str" __t "      " __reg_oper0 ", [%1]\n"      ) \
 459  THUMB( "1:     str" __t "      " __reg_oper1 ", [%1]\n"      ) \
 460  THUMB( "2:     str" __t "      " __reg_oper0 ", [%1, #4]\n"  ) \
 461         "3:\n"                                                  \
 462         "       .pushsection .text.fixup,\"ax\"\n"              \
 463         "       .align  2\n"                                    \
 464         "4:     mov     %0, %3\n"                               \
 465         "       b       3b\n"                                   \
 466         "       .popsection\n"                                  \
 467         "       .pushsection __ex_table,\"a\"\n"                \
 468         "       .align  3\n"                                    \
 469         "       .long   1b, 4b\n"                               \
 470         "       .long   2b, 4b\n"                               \
 471         "       .popsection"                                    \
 472         : "+r" (err), "+r" (__pu_addr)                          \
 473         : "r" (x), "i" (-EFAULT)                                \
 474         : "cc")
 475
 476 #define HAVE_GET_KERNEL_NOFAULT
 477
 478 #define __get_kernel_nofault(dst, src, type, err_label)                 \
 479 do {                                                                    \
 480         const type *__pk_ptr = (src);                                   \
 481         unsigned long __src = (unsigned long)(__pk_ptr);                \
 482         type __val;                                                     \
 483         int __err = 0;                                                  \
 484         switch (sizeof(type)) {                                         \
 485         case 1: __get_user_asm_byte(__val, __src, __err, ""); break;    \
 486         case 2: __get_user_asm_half(__val, __src, __err, ""); break;    \
 487         case 4: __get_user_asm_word(__val, __src, __err, ""); break;    \
 488         case 8: {                                                       \
 489                 u32 *__v32 = (u32*)&__val;                              \
 490                 __get_user_asm_word(__v32[0], __src, __err, "");        \
 491                 if (__err)                                              \
 492                         break;                                          \
 493                 __get_user_asm_word(__v32[1], __src+4, __err, "");      \
 494                 break;                                                  \
 495         }                                                               \
 496         default: __err = __get_user_bad(); break;                       \
 497         }                                                               \
 498         *(type *)(dst) = __val;                                         \
 499         if (__err)                                                      \
 500                 goto err_label;                                         \
 501 } while (0)
 502
 503 #define __put_kernel_nofault(dst, src, type, err_label)                 \
 504 do {                                                                    \
 505         const type *__pk_ptr = (dst);                                   \
 506         unsigned long __dst = (unsigned long)__pk_ptr;                  \
 507         int __err = 0;                                                  \
 508         type __val = *(type *)src;                                      \
 509         switch (sizeof(type)) {                                         \
 510         case 1: __put_user_asm_byte(__val, __dst, __err, ""); break;    \
 511         case 2: __put_user_asm_half(__val, __dst, __err, ""); break;    \
 512         case 4: __put_user_asm_word(__val, __dst, __err, ""); break;    \
 513         case 8: __put_user_asm_dword(__val, __dst, __err, ""); break;   \
 514         default: __err = __put_user_bad(); break;                       \
 515         }                                                               \
 516         if (__err)                                                      \
 517                 goto err_label;                                         \
 518 } while (0)
 519
 520 #ifdef CONFIG_MMU
 521 extern unsigned long __must_check
 522 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 523
 524 static inline unsigned long __must_check
 525 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 526 {
 527         unsigned int __ua_flags;
 528
 529         __ua_flags = uaccess_save_and_enable();
 530         n = arm_copy_from_user(to, from, n);
 531         uaccess_restore(__ua_flags);
 532         return n;
 533 }
 534
 535 extern unsigned long __must_check
 536 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 537 extern unsigned long __must_check
 538 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 539
 540 static inline unsigned long __must_check
 541 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 542 {
 543 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 544         unsigned int __ua_flags;
 545         __ua_flags = uaccess_save_and_enable();
 546         n = arm_copy_to_user(to, from, n);
 547         uaccess_restore(__ua_flags);
 548         return n;
 549 #else
 550         return arm_copy_to_user(to, from, n);
 551 #endif
 552 }
 553
 554 extern unsigned long __must_check
 555 arm_clear_user(void __user *addr, unsigned long n);
 556 extern unsigned long __must_check
 557 __clear_user_std(void __user *addr, unsigned long n);
 558
 559 static inline unsigned long __must_check
 560 __clear_user(void __user *addr, unsigned long n)
 561 {
 562         unsigned int __ua_flags = uaccess_save_and_enable();
 563         n = arm_clear_user(addr, n);
 564         uaccess_restore(__ua_flags);
 565         return n;
 566 }
 567
 568 #else
 569 static inline unsigned long
 570 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 571 {
 572         memcpy(to, (const void __force *)from, n);
 573         return 0;
 574 }
 575 static inline unsigned long
 576 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 577 {
 578         memcpy((void __force *)to, from, n);
 579         return 0;
 580 }
 581 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 582 #endif
 583 #define INLINE_COPY_TO_USER
 584 #define INLINE_COPY_FROM_USER
 585
 586 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 587 {
 588         if (access_ok(to, n))
 589                 n = __clear_user(to, n);
 590         return n;
 591 }
 592
 593 /* These are from lib/ code, and use __get_user() and friends */
 594 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 595
 596 extern __must_check long strnlen_user(const char __user *str, long n);
 597
 598 #endif /* _ASMARM_UACCESS_H */