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/pgtable.h>
  18 #include <asm/proc-fns.h>
  19 #include <asm/compiler.h>
  20
  21 #include <asm/extable.h>
  22
  23 /*
  24  * These two functions allow hooking accesses to userspace to increase
  25  * system integrity by ensuring that the kernel can not inadvertantly
  26  * perform such accesses (eg, via list poison values) which could then
  27  * be exploited for priviledge escalation.
  28  */
  29 #if defined(CONFIG_CPU_SW_DOMAIN_PAN)
  30
  31 static __always_inline unsigned int uaccess_save_and_enable(void)
  32 {
  33         unsigned int old_domain = get_domain();
  34
  35         /* Set the current domain access to permit user accesses */
  36         set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
  37                    domain_val(DOMAIN_USER, DOMAIN_CLIENT));
  38
  39         return old_domain;
  40 }
  41
  42 static __always_inline void uaccess_restore(unsigned int flags)
  43 {
  44         /* Restore the user access mask */
  45         set_domain(flags);
  46 }
  47
  48 #elif defined(CONFIG_CPU_TTBR0_PAN)
  49
  50 static __always_inline unsigned int uaccess_save_and_enable(void)
  51 {
  52         unsigned int old_ttbcr = cpu_get_ttbcr();
  53
  54         /*
  55          * Enable TTBR0 page table walks (T0SZ = 0, EDP0 = 0) and ASID from
  56          * TTBR0 (A1 = 0).
  57          */
  58         cpu_set_ttbcr(old_ttbcr & ~(TTBCR_A1 | TTBCR_EPD0 | TTBCR_T0SZ_MASK));
  59         isb();
  60
  61         return old_ttbcr;
  62 }
  63
  64 static inline void uaccess_restore(unsigned int flags)
  65 {
  66         cpu_set_ttbcr(flags);
  67         isb();
  68 }
  69
  70 #else
  71
  72 static inline unsigned int uaccess_save_and_enable(void)
  73 {
  74         return 0;
  75 }
  76
  77 static inline void uaccess_restore(unsigned int flags)
  78 {
  79 }
  80
  81 #endif
  82
  83 /*
  84  * These two are intentionally not defined anywhere - if the kernel
  85  * code generates any references to them, that's a bug.
  86  */
  87 extern int __get_user_bad(void);
  88 extern int __put_user_bad(void);
  89
  90 #ifdef CONFIG_MMU
  91
  92 /*
  93  * This is a type: either unsigned long, if the argument fits into
  94  * that type, or otherwise unsigned long long.
  95  */
  96 #define __inttype(x) \
  97         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
  98
  99 /*
 100  * Sanitise a uaccess pointer such that it becomes NULL if addr+size
 101  * is above the current addr_limit.
 102  */
 103 #define uaccess_mask_range_ptr(ptr, size)                       \
 104         ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
 105 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
 106                                                     size_t size)
 107 {
 108         void __user *safe_ptr = (void __user *)ptr;
 109         unsigned long tmp;
 110
 111         asm volatile(
 112         "       .syntax unified\n"
 113         "       sub     %1, %3, #1\n"
 114         "       subs    %1, %1, %0\n"
 115         "       addhs   %1, %1, #1\n"
 116         "       subshs  %1, %1, %2\n"
 117         "       movlo   %0, #0\n"
 118         : "+r" (safe_ptr), "=&r" (tmp)
 119         : "r" (size), "r" (TASK_SIZE)
 120         : "cc");
 121
 122         csdb();
 123         return safe_ptr;
 124 }
 125
 126 /*
 127  * Single-value transfer routines.  They automatically use the right
 128  * size if we just have the right pointer type.  Note that the functions
 129  * which read from user space (*get_*) need to take care not to leak
 130  * kernel data even if the calling code is buggy and fails to check
 131  * the return value.  This means zeroing out the destination variable
 132  * or buffer on error.  Normally this is done out of line by the
 133  * fixup code, but there are a few places where it intrudes on the
 134  * main code path.  When we only write to user space, there is no
 135  * problem.
 136  */
 137 extern int __get_user_1(void *);
 138 extern int __get_user_2(void *);
 139 extern int __get_user_4(void *);
 140 extern int __get_user_32t_8(void *);
 141 extern int __get_user_8(void *);
 142 extern int __get_user_64t_1(void *);
 143 extern int __get_user_64t_2(void *);
 144 extern int __get_user_64t_4(void *);
 145
 146 #define __get_user_x(__r2, __p, __e, __l, __s)                          \
 147            __asm__ __volatile__ (                                       \
 148                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 149                 __asmeq("%3", "r1")                                     \
 150                 "bl     __get_user_" #__s                               \
 151                 : "=&r" (__e), "=r" (__r2)                              \
 152                 : "0" (__p), "r" (__l)                                  \
 153                 : "ip", "lr", "cc")
 154
 155 /* narrowing a double-word get into a single 32bit word register: */
 156 #ifdef __ARMEB__
 157 #define __get_user_x_32t(__r2, __p, __e, __l, __s)                      \
 158         __get_user_x(__r2, __p, __e, __l, 32t_8)
 159 #else
 160 #define __get_user_x_32t __get_user_x
 161 #endif
 162
 163 /*
 164  * storing result into proper least significant word of 64bit target var,
 165  * different only for big endian case where 64 bit __r2 lsw is r3:
 166  */
 167 #ifdef __ARMEB__
 168 #define __get_user_x_64t(__r2, __p, __e, __l, __s)                      \
 169            __asm__ __volatile__ (                                       \
 170                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 171                 __asmeq("%3", "r1")                                     \
 172                 "bl     __get_user_64t_" #__s                           \
 173                 : "=&r" (__e), "=r" (__r2)                              \
 174                 : "0" (__p), "r" (__l)                                  \
 175                 : "ip", "lr", "cc")
 176 #else
 177 #define __get_user_x_64t __get_user_x
 178 #endif
 179
 180
 181 #define __get_user_check(x, p)                                          \
 182         ({                                                              \
 183                 unsigned long __limit = TASK_SIZE - 1; \
 184                 register typeof(*(p)) __user *__p asm("r0") = (p);      \
 185                 register __inttype(x) __r2 asm("r2");                   \
 186                 register unsigned long __l asm("r1") = __limit;         \
 187                 register int __e asm("r0");                             \
 188                 unsigned int __ua_flags = uaccess_save_and_enable();    \
 189                 int __tmp_e;                                            \
 190                 switch (sizeof(*(__p))) {                               \
 191                 case 1:                                                 \
 192                         if (sizeof((x)) >= 8)                           \
 193                                 __get_user_x_64t(__r2, __p, __e, __l, 1); \
 194                         else                                            \
 195                                 __get_user_x(__r2, __p, __e, __l, 1);   \
 196                         break;                                          \
 197                 case 2:                                                 \
 198                         if (sizeof((x)) >= 8)                           \
 199                                 __get_user_x_64t(__r2, __p, __e, __l, 2); \
 200                         else                                            \
 201                                 __get_user_x(__r2, __p, __e, __l, 2);   \
 202                         break;                                          \
 203                 case 4:                                                 \
 204                         if (sizeof((x)) >= 8)                           \
 205                                 __get_user_x_64t(__r2, __p, __e, __l, 4); \
 206                         else                                            \
 207                                 __get_user_x(__r2, __p, __e, __l, 4);   \
 208                         break;                                          \
 209                 case 8:                                                 \
 210                         if (sizeof((x)) < 8)                            \
 211                                 __get_user_x_32t(__r2, __p, __e, __l, 4); \
 212                         else                                            \
 213                                 __get_user_x(__r2, __p, __e, __l, 8);   \
 214                         break;                                          \
 215                 default: __e = __get_user_bad(); break;                 \
 216                 }                                                       \
 217                 __tmp_e = __e;                                          \
 218                 uaccess_restore(__ua_flags);                            \
 219                 x = (typeof(*(p))) __r2;                                \
 220                 __tmp_e;                                                \
 221         })
 222
 223 #define get_user(x, p)                                                  \
 224         ({                                                              \
 225                 might_fault();                                          \
 226                 __get_user_check(x, p);                                 \
 227          })
 228
 229 extern int __put_user_1(void *, unsigned int);
 230 extern int __put_user_2(void *, unsigned int);
 231 extern int __put_user_4(void *, unsigned int);
 232 extern int __put_user_8(void *, unsigned long long);
 233
 234 #define __put_user_check(__pu_val, __ptr, __err, __s)                   \
 235         ({                                                              \
 236                 unsigned long __limit = TASK_SIZE - 1; \
 237                 register typeof(__pu_val) __r2 asm("r2") = __pu_val;    \
 238                 register const void __user *__p asm("r0") = __ptr;      \
 239                 register unsigned long __l asm("r1") = __limit;         \
 240                 register int __e asm("r0");                             \
 241                 __asm__ __volatile__ (                                  \
 242                         __asmeq("%0", "r0") __asmeq("%2", "r2")         \
 243                         __asmeq("%3", "r1")                             \
 244                         "bl     __put_user_" #__s                       \
 245                         : "=&r" (__e)                                   \
 246                         : "0" (__p), "r" (__r2), "r" (__l)              \
 247                         : "ip", "lr", "cc");                            \
 248                 __err = __e;                                            \
 249         })
 250
 251 #else /* CONFIG_MMU */
 252
 253 #define get_user(x, p)  __get_user(x, p)
 254 #define __put_user_check __put_user_nocheck
 255
 256 #endif /* CONFIG_MMU */
 257
 258 #include <asm-generic/access_ok.h>
 259
 260 #ifdef CONFIG_CPU_SPECTRE
 261 /*
 262  * When mitigating Spectre variant 1, it is not worth fixing the non-
 263  * verifying accessors, because we need to add verification of the
 264  * address space there.  Force these to use the standard get_user()
 265  * version instead.
 266  */
 267 #define __get_user(x, ptr) get_user(x, ptr)
 268 #else
 269
 270 /*
 271  * The "__xxx" versions of the user access functions do not verify the
 272  * address space - it must have been done previously with a separate
 273  * "access_ok()" call.
 274  *
 275  * The "xxx_error" versions set the third argument to EFAULT if an
 276  * error occurs, and leave it unchanged on success.  Note that these
 277  * versions are void (ie, don't return a value as such).
 278  */
 279 #define __get_user(x, ptr)                                              \
 280 ({                                                                      \
 281         long __gu_err = 0;                                              \
 282         __get_user_err((x), (ptr), __gu_err, TUSER());                  \
 283         __gu_err;                                                       \
 284 })
 285
 286 #define __get_user_err(x, ptr, err, __t)                                \
 287 do {                                                                    \
 288         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 289         unsigned long __gu_val;                                         \
 290         unsigned int __ua_flags;                                        \
 291         __chk_user_ptr(ptr);                                            \
 292         might_fault();                                                  \
 293         __ua_flags = uaccess_save_and_enable();                         \
 294         switch (sizeof(*(ptr))) {                                       \
 295         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break;      \
 296         case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break;      \
 297         case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break;      \
 298         default: (__gu_val) = __get_user_bad();                         \
 299         }                                                               \
 300         uaccess_restore(__ua_flags);                                    \
 301         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 302 } while (0)
 303 #endif
 304
 305 #define __get_user_asm(x, addr, err, instr)                     \
 306         __asm__ __volatile__(                                   \
 307         "1:     " instr " %1, [%2], #0\n"                       \
 308         "2:\n"                                                  \
 309         "       .pushsection .text.fixup,\"ax\"\n"              \
 310         "       .align  2\n"                                    \
 311         "3:     mov     %0, %3\n"                               \
 312         "       mov     %1, #0\n"                               \
 313         "       b       2b\n"                                   \
 314         "       .popsection\n"                                  \
 315         "       .pushsection __ex_table,\"a\"\n"                \
 316         "       .align  3\n"                                    \
 317         "       .long   1b, 3b\n"                               \
 318         "       .popsection"                                    \
 319         : "+r" (err), "=&r" (x)                                 \
 320         : "r" (addr), "i" (-EFAULT)                             \
 321         : "cc")
 322
 323 #define __get_user_asm_byte(x, addr, err, __t)                  \
 324         __get_user_asm(x, addr, err, "ldrb" __t)
 325
 326 #if __LINUX_ARM_ARCH__ >= 6
 327
 328 #define __get_user_asm_half(x, addr, err, __t)                  \
 329         __get_user_asm(x, addr, err, "ldrh" __t)
 330
 331 #else
 332
 333 #ifndef __ARMEB__
 334 #define __get_user_asm_half(x, __gu_addr, err, __t)             \
 335 ({                                                              \
 336         unsigned long __b1, __b2;                               \
 337         __get_user_asm_byte(__b1, __gu_addr, err, __t);         \
 338         __get_user_asm_byte(__b2, __gu_addr + 1, err, __t);     \
 339         (x) = __b1 | (__b2 << 8);                               \
 340 })
 341 #else
 342 #define __get_user_asm_half(x, __gu_addr, err, __t)             \
 343 ({                                                              \
 344         unsigned long __b1, __b2;                               \
 345         __get_user_asm_byte(__b1, __gu_addr, err, __t);         \
 346         __get_user_asm_byte(__b2, __gu_addr + 1, err, __t);     \
 347         (x) = (__b1 << 8) | __b2;                               \
 348 })
 349 #endif
 350
 351 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 352
 353 #define __get_user_asm_word(x, addr, err, __t)                  \
 354         __get_user_asm(x, addr, err, "ldr" __t)
 355
 356 #define __put_user_switch(x, ptr, __err, __fn)                          \
 357         do {                                                            \
 358                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 359                 __typeof__(*(ptr)) __pu_val = (x);                      \
 360                 unsigned int __ua_flags;                                \
 361                 might_fault();                                          \
 362                 __ua_flags = uaccess_save_and_enable();                 \
 363                 switch (sizeof(*(ptr))) {                               \
 364                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 365                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 366                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 367                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 368                 default: __err = __put_user_bad(); break;               \
 369                 }                                                       \
 370                 uaccess_restore(__ua_flags);                            \
 371         } while (0)
 372
 373 #define put_user(x, ptr)                                                \
 374 ({                                                                      \
 375         int __pu_err = 0;                                               \
 376         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 377         __pu_err;                                                       \
 378 })
 379
 380 #ifdef CONFIG_CPU_SPECTRE
 381 /*
 382  * When mitigating Spectre variant 1.1, all accessors need to include
 383  * verification of the address space.
 384  */
 385 #define __put_user(x, ptr) put_user(x, ptr)
 386
 387 #else
 388 #define __put_user(x, ptr)                                              \
 389 ({                                                                      \
 390         long __pu_err = 0;                                              \
 391         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 392         __pu_err;                                                       \
 393 })
 394
 395 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 396         do {                                                            \
 397                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 398                 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\
 399         } while (0)
 400
 401 #define __put_user_nocheck_1 __put_user_asm_byte
 402 #define __put_user_nocheck_2 __put_user_asm_half
 403 #define __put_user_nocheck_4 __put_user_asm_word
 404 #define __put_user_nocheck_8 __put_user_asm_dword
 405
 406 #endif /* !CONFIG_CPU_SPECTRE */
 407
 408 #define __put_user_asm(x, __pu_addr, err, instr)                \
 409         __asm__ __volatile__(                                   \
 410         "1:     " instr " %1, [%2], #0\n"               \
 411         "2:\n"                                                  \
 412         "       .pushsection .text.fixup,\"ax\"\n"              \
 413         "       .align  2\n"                                    \
 414         "3:     mov     %0, %3\n"                               \
 415         "       b       2b\n"                                   \
 416         "       .popsection\n"                                  \
 417         "       .pushsection __ex_table,\"a\"\n"                \
 418         "       .align  3\n"                                    \
 419         "       .long   1b, 3b\n"                               \
 420         "       .popsection"                                    \
 421         : "+r" (err)                                            \
 422         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 423         : "cc")
 424
 425 #define __put_user_asm_byte(x, __pu_addr, err, __t)             \
 426         __put_user_asm(x, __pu_addr, err, "strb" __t)
 427
 428 #if __LINUX_ARM_ARCH__ >= 6
 429
 430 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 431         __put_user_asm(x, __pu_addr, err, "strh" __t)
 432
 433 #else
 434
 435 #ifndef __ARMEB__
 436 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 437 ({                                                              \
 438         unsigned long __temp = (__force unsigned long)(x);      \
 439         __put_user_asm_byte(__temp, __pu_addr, err, __t);       \
 440         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\
 441 })
 442 #else
 443 #define __put_user_asm_half(x, __pu_addr, err, __t)             \
 444 ({                                                              \
 445         unsigned long __temp = (__force unsigned long)(x);      \
 446         __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t);  \
 447         __put_user_asm_byte(__temp, __pu_addr + 1, err, __t);   \
 448 })
 449 #endif
 450
 451 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 452
 453 #define __put_user_asm_word(x, __pu_addr, err, __t)             \
 454         __put_user_asm(x, __pu_addr, err, "str" __t)
 455
 456 #ifndef __ARMEB__
 457 #define __reg_oper0     "%R2"
 458 #define __reg_oper1     "%Q2"
 459 #else
 460 #define __reg_oper0     "%Q2"
 461 #define __reg_oper1     "%R2"
 462 #endif
 463
 464 #define __put_user_asm_dword(x, __pu_addr, err, __t)            \
 465         __asm__ __volatile__(                                   \
 466  ARM(   "1:     str" __t "      " __reg_oper1 ", [%1], #4\n"  ) \
 467  ARM(   "2:     str" __t "      " __reg_oper0 ", [%1]\n"      ) \
 468  THUMB( "1:     str" __t "      " __reg_oper1 ", [%1]\n"      ) \
 469  THUMB( "2:     str" __t "      " __reg_oper0 ", [%1, #4]\n"  ) \
 470         "3:\n"                                                  \
 471         "       .pushsection .text.fixup,\"ax\"\n"              \
 472         "       .align  2\n"                                    \
 473         "4:     mov     %0, %3\n"                               \
 474         "       b       3b\n"                                   \
 475         "       .popsection\n"                                  \
 476         "       .pushsection __ex_table,\"a\"\n"                \
 477         "       .align  3\n"                                    \
 478         "       .long   1b, 4b\n"                               \
 479         "       .long   2b, 4b\n"                               \
 480         "       .popsection"                                    \
 481         : "+r" (err), "+r" (__pu_addr)                          \
 482         : "r" (x), "i" (-EFAULT)                                \
 483         : "cc")
 484
 485 #define __get_kernel_nofault(dst, src, type, err_label)                 \
 486 do {                                                                    \
 487         const type *__pk_ptr = (src);                                   \
 488         unsigned long __src = (unsigned long)(__pk_ptr);                \
 489         type __val;                                                     \
 490         int __err = 0;                                                  \
 491         switch (sizeof(type)) {                                         \
 492         case 1: __get_user_asm_byte(__val, __src, __err, ""); break;    \
 493         case 2: __get_user_asm_half(__val, __src, __err, ""); break;    \
 494         case 4: __get_user_asm_word(__val, __src, __err, ""); break;    \
 495         case 8: {                                                       \
 496                 u32 *__v32 = (u32*)&__val;                              \
 497                 __get_user_asm_word(__v32[0], __src, __err, "");        \
 498                 if (__err)                                              \
 499                         break;                                          \
 500                 __get_user_asm_word(__v32[1], __src+4, __err, "");      \
 501                 break;                                                  \
 502         }                                                               \
 503         default: __err = __get_user_bad(); break;                       \
 504         }                                                               \
 505         if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))         \
 506                 put_unaligned(__val, (type *)(dst));                    \
 507         else                                                            \
 508                 *(type *)(dst) = __val; /* aligned by caller */         \
 509         if (__err)                                                      \
 510                 goto err_label;                                         \
 511 } while (0)
 512
 513 #define __put_kernel_nofault(dst, src, type, err_label)                 \
 514 do {                                                                    \
 515         const type *__pk_ptr = (dst);                                   \
 516         unsigned long __dst = (unsigned long)__pk_ptr;                  \
 517         int __err = 0;                                                  \
 518         type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \
 519                      ? get_unaligned((type *)(src))                     \
 520                      : *(type *)(src);  /* aligned by caller */         \
 521         switch (sizeof(type)) {                                         \
 522         case 1: __put_user_asm_byte(__val, __dst, __err, ""); break;    \
 523         case 2: __put_user_asm_half(__val, __dst, __err, ""); break;    \
 524         case 4: __put_user_asm_word(__val, __dst, __err, ""); break;    \
 525         case 8: __put_user_asm_dword(__val, __dst, __err, ""); break;   \
 526         default: __err = __put_user_bad(); break;                       \
 527         }                                                               \
 528         if (__err)                                                      \
 529                 goto err_label;                                         \
 530 } while (0)
 531
 532 #ifdef CONFIG_MMU
 533 extern unsigned long __must_check
 534 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 535
 536 static inline unsigned long __must_check
 537 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 538 {
 539         unsigned int __ua_flags;
 540
 541         __ua_flags = uaccess_save_and_enable();
 542         n = arm_copy_from_user(to, from, n);
 543         uaccess_restore(__ua_flags);
 544         return n;
 545 }
 546
 547 extern unsigned long __must_check
 548 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 549 extern unsigned long __must_check
 550 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 551
 552 static inline unsigned long __must_check
 553 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 554 {
 555 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 556         unsigned int __ua_flags;
 557         __ua_flags = uaccess_save_and_enable();
 558         n = arm_copy_to_user(to, from, n);
 559         uaccess_restore(__ua_flags);
 560         return n;
 561 #else
 562         return arm_copy_to_user(to, from, n);
 563 #endif
 564 }
 565
 566 extern unsigned long __must_check
 567 arm_clear_user(void __user *addr, unsigned long n);
 568 extern unsigned long __must_check
 569 __clear_user_std(void __user *addr, unsigned long n);
 570
 571 static inline unsigned long __must_check
 572 __clear_user(void __user *addr, unsigned long n)
 573 {
 574         unsigned int __ua_flags = uaccess_save_and_enable();
 575         n = arm_clear_user(addr, n);
 576         uaccess_restore(__ua_flags);
 577         return n;
 578 }
 579
 580 #else
 581 static inline unsigned long
 582 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 583 {
 584         memcpy(to, (const void __force *)from, n);
 585         return 0;
 586 }
 587 static inline unsigned long
 588 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 589 {
 590         memcpy((void __force *)to, from, n);
 591         return 0;
 592 }
 593 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 594 #endif
 595 #define INLINE_COPY_TO_USER
 596 #define INLINE_COPY_FROM_USER
 597
 598 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 599 {
 600         if (access_ok(to, n))
 601                 n = __clear_user(to, n);
 602         return n;
 603 }
 604
 605 /* These are from lib/ code, and use __get_user() and friends */
 606 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 607
 608 extern __must_check long strnlen_user(const char __user *str, long n);
 609
 610 #endif /* _ASMARM_UACCESS_H */