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 <linux/thread_info.h>
  16 #include <asm/errno.h>
  17 #include <asm/memory.h>
  18 #include <asm/domain.h>
  19 #include <asm/unified.h>
  20 #include <asm/compiler.h>
  21
  22 #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  23 #include <asm-generic/uaccess-unaligned.h>
  24 #else
  25 #define __get_user_unaligned __get_user
  26 #define __put_user_unaligned __put_user
  27 #endif
  28
  29 #define VERIFY_READ 0
  30 #define VERIFY_WRITE 1
  31
  32 /*
  33  * The exception table consists of pairs of addresses: the first is the
  34  * address of an instruction that is allowed to fault, and the second is
  35  * the address at which the program should continue.  No registers are
  36  * modified, so it is entirely up to the continuation code to figure out
  37  * what to do.
  38  *
  39  * All the routines below use bits of fixup code that are out of line
  40  * with the main instruction path.  This means when everything is well,
  41  * we don't even have to jump over them.  Further, they do not intrude
  42  * on our cache or tlb entries.
  43  */
  44
  45 struct exception_table_entry
  46 {
  47         unsigned long insn, fixup;
  48 };
  49
  50 extern int fixup_exception(struct pt_regs *regs);
  51
  52 /*
  53  * These two functions allow hooking accesses to userspace to increase
  54  * system integrity by ensuring that the kernel can not inadvertantly
  55  * perform such accesses (eg, via list poison values) which could then
  56  * be exploited for priviledge escalation.
  57  */
  58 static inline unsigned int uaccess_save_and_enable(void)
  59 {
  60 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  61         unsigned int old_domain = get_domain();
  62
  63         /* Set the current domain access to permit user accesses */
  64         set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
  65                    domain_val(DOMAIN_USER, DOMAIN_CLIENT));
  66
  67         return old_domain;
  68 #else
  69         return 0;
  70 #endif
  71 }
  72
  73 static inline void uaccess_restore(unsigned int flags)
  74 {
  75 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  76         /* Restore the user access mask */
  77         set_domain(flags);
  78 #endif
  79 }
  80
  81 /*
  82  * These two are intentionally not defined anywhere - if the kernel
  83  * code generates any references to them, that's a bug.
  84  */
  85 extern int __get_user_bad(void);
  86 extern int __put_user_bad(void);
  87
  88 /*
  89  * Note that this is actually 0x1,0000,0000
  90  */
  91 #define KERNEL_DS       0x00000000
  92 #define get_ds()        (KERNEL_DS)
  93
  94 #ifdef CONFIG_MMU
  95
  96 #define USER_DS         TASK_SIZE
  97 #define get_fs()        (current_thread_info()->addr_limit)
  98
  99 static inline void set_fs(mm_segment_t fs)
 100 {
 101         current_thread_info()->addr_limit = fs;
 102
 103         /*
 104          * Prevent a mispredicted conditional call to set_fs from forwarding
 105          * the wrong address limit to access_ok under speculation.
 106          */
 107         dsb(nsh);
 108         isb();
 109
 110         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
 111 }
 112
 113 #define segment_eq(a, b)        ((a) == (b))
 114
 115 #define __addr_ok(addr) ({ \
 116         unsigned long flag; \
 117         __asm__("cmp %2, %0; movlo %0, #0" \
 118                 : "=&r" (flag) \
 119                 : "0" (current_thread_info()->addr_limit), "r" (addr) \
 120                 : "cc"); \
 121         (flag == 0); })
 122
 123 /* We use 33-bit arithmetic here... */
 124 #define __range_ok(addr, size) ({ \
 125         unsigned long flag, roksum; \
 126         __chk_user_ptr(addr);   \
 127         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
 128                 : "=&r" (flag), "=&r" (roksum) \
 129                 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
 130                 : "cc"); \
 131         flag; })
 132
 133 /*
 134  * This is a type: either unsigned long, if the argument fits into
 135  * that type, or otherwise unsigned long long.
 136  */
 137 #define __inttype(x) \
 138         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 139
 140 /*
 141  * Sanitise a uaccess pointer such that it becomes NULL if addr+size
 142  * is above the current addr_limit.
 143  */
 144 #define uaccess_mask_range_ptr(ptr, size)                       \
 145         ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
 146 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
 147                                                     size_t size)
 148 {
 149         void __user *safe_ptr = (void __user *)ptr;
 150         unsigned long tmp;
 151
 152         asm volatile(
 153         "       sub     %1, %3, #1\n"
 154         "       subs    %1, %1, %0\n"
 155         "       addhs   %1, %1, #1\n"
 156         "       subhss  %1, %1, %2\n"
 157         "       movlo   %0, #0\n"
 158         : "+r" (safe_ptr), "=&r" (tmp)
 159         : "r" (size), "r" (current_thread_info()->addr_limit)
 160         : "cc");
 161
 162         csdb();
 163         return safe_ptr;
 164 }
 165
 166 /*
 167  * Single-value transfer routines.  They automatically use the right
 168  * size if we just have the right pointer type.  Note that the functions
 169  * which read from user space (*get_*) need to take care not to leak
 170  * kernel data even if the calling code is buggy and fails to check
 171  * the return value.  This means zeroing out the destination variable
 172  * or buffer on error.  Normally this is done out of line by the
 173  * fixup code, but there are a few places where it intrudes on the
 174  * main code path.  When we only write to user space, there is no
 175  * problem.
 176  */
 177 extern int __get_user_1(void *);
 178 extern int __get_user_2(void *);
 179 extern int __get_user_4(void *);
 180 extern int __get_user_32t_8(void *);
 181 extern int __get_user_8(void *);
 182 extern int __get_user_64t_1(void *);
 183 extern int __get_user_64t_2(void *);
 184 extern int __get_user_64t_4(void *);
 185
 186 #define __GUP_CLOBBER_1 "lr", "cc"
 187 #ifdef CONFIG_CPU_USE_DOMAINS
 188 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
 189 #else
 190 #define __GUP_CLOBBER_2 "lr", "cc"
 191 #endif
 192 #define __GUP_CLOBBER_4 "lr", "cc"
 193 #define __GUP_CLOBBER_32t_8 "lr", "cc"
 194 #define __GUP_CLOBBER_8 "lr", "cc"
 195
 196 #define __get_user_x(__r2, __p, __e, __l, __s)                          \
 197            __asm__ __volatile__ (                                       \
 198                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 199                 __asmeq("%3", "r1")                                     \
 200                 "bl     __get_user_" #__s                               \
 201                 : "=&r" (__e), "=r" (__r2)                              \
 202                 : "0" (__p), "r" (__l)                                  \
 203                 : __GUP_CLOBBER_##__s)
 204
 205 /* narrowing a double-word get into a single 32bit word register: */
 206 #ifdef __ARMEB__
 207 #define __get_user_x_32t(__r2, __p, __e, __l, __s)                      \
 208         __get_user_x(__r2, __p, __e, __l, 32t_8)
 209 #else
 210 #define __get_user_x_32t __get_user_x
 211 #endif
 212
 213 /*
 214  * storing result into proper least significant word of 64bit target var,
 215  * different only for big endian case where 64 bit __r2 lsw is r3:
 216  */
 217 #ifdef __ARMEB__
 218 #define __get_user_x_64t(__r2, __p, __e, __l, __s)                      \
 219            __asm__ __volatile__ (                                       \
 220                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 221                 __asmeq("%3", "r1")                                     \
 222                 "bl     __get_user_64t_" #__s                           \
 223                 : "=&r" (__e), "=r" (__r2)                              \
 224                 : "0" (__p), "r" (__l)                                  \
 225                 : __GUP_CLOBBER_##__s)
 226 #else
 227 #define __get_user_x_64t __get_user_x
 228 #endif
 229
 230
 231 #define __get_user_check(x, p)                                          \
 232         ({                                                              \
 233                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 234                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 235                 register __inttype(x) __r2 asm("r2");                   \
 236                 register unsigned long __l asm("r1") = __limit;         \
 237                 register int __e asm("r0");                             \
 238                 unsigned int __ua_flags = uaccess_save_and_enable();    \
 239                 switch (sizeof(*(__p))) {                               \
 240                 case 1:                                                 \
 241                         if (sizeof((x)) >= 8)                           \
 242                                 __get_user_x_64t(__r2, __p, __e, __l, 1); \
 243                         else                                            \
 244                                 __get_user_x(__r2, __p, __e, __l, 1);   \
 245                         break;                                          \
 246                 case 2:                                                 \
 247                         if (sizeof((x)) >= 8)                           \
 248                                 __get_user_x_64t(__r2, __p, __e, __l, 2); \
 249                         else                                            \
 250                                 __get_user_x(__r2, __p, __e, __l, 2);   \
 251                         break;                                          \
 252                 case 4:                                                 \
 253                         if (sizeof((x)) >= 8)                           \
 254                                 __get_user_x_64t(__r2, __p, __e, __l, 4); \
 255                         else                                            \
 256                                 __get_user_x(__r2, __p, __e, __l, 4);   \
 257                         break;                                          \
 258                 case 8:                                                 \
 259                         if (sizeof((x)) < 8)                            \
 260                                 __get_user_x_32t(__r2, __p, __e, __l, 4); \
 261                         else                                            \
 262                                 __get_user_x(__r2, __p, __e, __l, 8);   \
 263                         break;                                          \
 264                 default: __e = __get_user_bad(); break;                 \
 265                 }                                                       \
 266                 uaccess_restore(__ua_flags);                            \
 267                 x = (typeof(*(p))) __r2;                                \
 268                 __e;                                                    \
 269         })
 270
 271 #define get_user(x, p)                                                  \
 272         ({                                                              \
 273                 might_fault();                                          \
 274                 __get_user_check(x, p);                                 \
 275          })
 276
 277 extern int __put_user_1(void *, unsigned int);
 278 extern int __put_user_2(void *, unsigned int);
 279 extern int __put_user_4(void *, unsigned int);
 280 extern int __put_user_8(void *, unsigned long long);
 281
 282 #define __put_user_check(__pu_val, __ptr, __err, __s)                   \
 283         ({                                                              \
 284                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 285                 register typeof(__pu_val) __r2 asm("r2") = __pu_val;    \
 286                 register const void __user *__p asm("r0") = __ptr;      \
 287                 register unsigned long __l asm("r1") = __limit;         \
 288                 register int __e asm("r0");                             \
 289                 __asm__ __volatile__ (                                  \
 290                         __asmeq("%0", "r0") __asmeq("%2", "r2")         \
 291                         __asmeq("%3", "r1")                             \
 292                         "bl     __put_user_" #__s                       \
 293                         : "=&r" (__e)                                   \
 294                         : "0" (__p), "r" (__r2), "r" (__l)              \
 295                         : "ip", "lr", "cc");                            \
 296                 __err = __e;                                            \
 297         })
 298
 299 #else /* CONFIG_MMU */
 300
 301 /*
 302  * uClinux has only one addr space, so has simplified address limits.
 303  */
 304 #define USER_DS                 KERNEL_DS
 305
 306 #define segment_eq(a, b)                (1)
 307 #define __addr_ok(addr)         ((void)(addr), 1)
 308 #define __range_ok(addr, size)  ((void)(addr), 0)
 309 #define get_fs()                (KERNEL_DS)
 310
 311 static inline void set_fs(mm_segment_t fs)
 312 {
 313 }
 314
 315 #define get_user(x, p)  __get_user(x, p)
 316 #define __put_user_check __put_user_nocheck
 317
 318 #endif /* CONFIG_MMU */
 319
 320 #define access_ok(type, addr, size)     (__range_ok(addr, size) == 0)
 321
 322 #define user_addr_max() \
 323         (segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs())
 324
 325 #ifdef CONFIG_CPU_SPECTRE
 326 /*
 327  * When mitigating Spectre variant 1, it is not worth fixing the non-
 328  * verifying accessors, because we need to add verification of the
 329  * address space there.  Force these to use the standard get_user()
 330  * version instead.
 331  */
 332 #define __get_user(x, ptr) get_user(x, ptr)
 333 #else
 334
 335 /*
 336  * The "__xxx" versions of the user access functions do not verify the
 337  * address space - it must have been done previously with a separate
 338  * "access_ok()" call.
 339  *
 340  * The "xxx_error" versions set the third argument to EFAULT if an
 341  * error occurs, and leave it unchanged on success.  Note that these
 342  * versions are void (ie, don't return a value as such).
 343  */
 344 #define __get_user(x, ptr)                                              \
 345 ({                                                                      \
 346         long __gu_err = 0;                                              \
 347         __get_user_err((x), (ptr), __gu_err);                           \
 348         __gu_err;                                                       \
 349 })
 350
 351 #define __get_user_err(x, ptr, err)                                     \
 352 do {                                                                    \
 353         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 354         unsigned long __gu_val;                                         \
 355         unsigned int __ua_flags;                                        \
 356         __chk_user_ptr(ptr);                                            \
 357         might_fault();                                                  \
 358         __ua_flags = uaccess_save_and_enable();                         \
 359         switch (sizeof(*(ptr))) {                                       \
 360         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err);  break;  \
 361         case 2: __get_user_asm_half(__gu_val, __gu_addr, err);  break;  \
 362         case 4: __get_user_asm_word(__gu_val, __gu_addr, err);  break;  \
 363         default: (__gu_val) = __get_user_bad();                         \
 364         }                                                               \
 365         uaccess_restore(__ua_flags);                                    \
 366         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 367 } while (0)
 368
 369 #define __get_user_asm(x, addr, err, instr)                     \
 370         __asm__ __volatile__(                                   \
 371         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 372         "2:\n"                                                  \
 373         "       .pushsection .text.fixup,\"ax\"\n"              \
 374         "       .align  2\n"                                    \
 375         "3:     mov     %0, %3\n"                               \
 376         "       mov     %1, #0\n"                               \
 377         "       b       2b\n"                                   \
 378         "       .popsection\n"                                  \
 379         "       .pushsection __ex_table,\"a\"\n"                \
 380         "       .align  3\n"                                    \
 381         "       .long   1b, 3b\n"                               \
 382         "       .popsection"                                    \
 383         : "+r" (err), "=&r" (x)                                 \
 384         : "r" (addr), "i" (-EFAULT)                             \
 385         : "cc")
 386
 387 #define __get_user_asm_byte(x, addr, err)                       \
 388         __get_user_asm(x, addr, err, ldrb)
 389
 390 #if __LINUX_ARM_ARCH__ >= 6
 391
 392 #define __get_user_asm_half(x, addr, err)                       \
 393         __get_user_asm(x, addr, err, ldrh)
 394
 395 #else
 396
 397 #ifndef __ARMEB__
 398 #define __get_user_asm_half(x, __gu_addr, err)                  \
 399 ({                                                              \
 400         unsigned long __b1, __b2;                               \
 401         __get_user_asm_byte(__b1, __gu_addr, err);              \
 402         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 403         (x) = __b1 | (__b2 << 8);                               \
 404 })
 405 #else
 406 #define __get_user_asm_half(x, __gu_addr, err)                  \
 407 ({                                                              \
 408         unsigned long __b1, __b2;                               \
 409         __get_user_asm_byte(__b1, __gu_addr, err);              \
 410         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 411         (x) = (__b1 << 8) | __b2;                               \
 412 })
 413 #endif
 414
 415 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 416
 417 #define __get_user_asm_word(x, addr, err)                       \
 418         __get_user_asm(x, addr, err, ldr)
 419 #endif
 420
 421
 422 #define __put_user_switch(x, ptr, __err, __fn)                          \
 423         do {                                                            \
 424                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 425                 __typeof__(*(ptr)) __pu_val = (x);                      \
 426                 unsigned int __ua_flags;                                \
 427                 might_fault();                                          \
 428                 __ua_flags = uaccess_save_and_enable();                 \
 429                 switch (sizeof(*(ptr))) {                               \
 430                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 431                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 432                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 433                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 434                 default: __err = __put_user_bad(); break;               \
 435                 }                                                       \
 436                 uaccess_restore(__ua_flags);                            \
 437         } while (0)
 438
 439 #define put_user(x, ptr)                                                \
 440 ({                                                                      \
 441         int __pu_err = 0;                                               \
 442         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 443         __pu_err;                                                       \
 444 })
 445
 446 #ifdef CONFIG_CPU_SPECTRE
 447 /*
 448  * When mitigating Spectre variant 1.1, all accessors need to include
 449  * verification of the address space.
 450  */
 451 #define __put_user(x, ptr) put_user(x, ptr)
 452
 453 #else
 454 #define __put_user(x, ptr)                                              \
 455 ({                                                                      \
 456         long __pu_err = 0;                                              \
 457         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 458         __pu_err;                                                       \
 459 })
 460
 461 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 462         do {                                                            \
 463                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 464                 __put_user_nocheck_##__size(x, __pu_addr, __err);       \
 465         } while (0)
 466
 467 #define __put_user_nocheck_1 __put_user_asm_byte
 468 #define __put_user_nocheck_2 __put_user_asm_half
 469 #define __put_user_nocheck_4 __put_user_asm_word
 470 #define __put_user_nocheck_8 __put_user_asm_dword
 471
 472 #define __put_user_asm(x, __pu_addr, err, instr)                \
 473         __asm__ __volatile__(                                   \
 474         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 475         "2:\n"                                                  \
 476         "       .pushsection .text.fixup,\"ax\"\n"              \
 477         "       .align  2\n"                                    \
 478         "3:     mov     %0, %3\n"                               \
 479         "       b       2b\n"                                   \
 480         "       .popsection\n"                                  \
 481         "       .pushsection __ex_table,\"a\"\n"                \
 482         "       .align  3\n"                                    \
 483         "       .long   1b, 3b\n"                               \
 484         "       .popsection"                                    \
 485         : "+r" (err)                                            \
 486         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 487         : "cc")
 488
 489 #define __put_user_asm_byte(x, __pu_addr, err)                  \
 490         __put_user_asm(x, __pu_addr, err, strb)
 491
 492 #if __LINUX_ARM_ARCH__ >= 6
 493
 494 #define __put_user_asm_half(x, __pu_addr, err)                  \
 495         __put_user_asm(x, __pu_addr, err, strh)
 496
 497 #else
 498
 499 #ifndef __ARMEB__
 500 #define __put_user_asm_half(x, __pu_addr, err)                  \
 501 ({                                                              \
 502         unsigned long __temp = (__force unsigned long)(x);      \
 503         __put_user_asm_byte(__temp, __pu_addr, err);            \
 504         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 505 })
 506 #else
 507 #define __put_user_asm_half(x, __pu_addr, err)                  \
 508 ({                                                              \
 509         unsigned long __temp = (__force unsigned long)(x);      \
 510         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 511         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 512 })
 513 #endif
 514
 515 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 516
 517 #define __put_user_asm_word(x, __pu_addr, err)                  \
 518         __put_user_asm(x, __pu_addr, err, str)
 519
 520 #ifndef __ARMEB__
 521 #define __reg_oper0     "%R2"
 522 #define __reg_oper1     "%Q2"
 523 #else
 524 #define __reg_oper0     "%Q2"
 525 #define __reg_oper1     "%R2"
 526 #endif
 527
 528 #define __put_user_asm_dword(x, __pu_addr, err)                 \
 529         __asm__ __volatile__(                                   \
 530  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 531  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 532  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 533  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 534         "3:\n"                                                  \
 535         "       .pushsection .text.fixup,\"ax\"\n"              \
 536         "       .align  2\n"                                    \
 537         "4:     mov     %0, %3\n"                               \
 538         "       b       3b\n"                                   \
 539         "       .popsection\n"                                  \
 540         "       .pushsection __ex_table,\"a\"\n"                \
 541         "       .align  3\n"                                    \
 542         "       .long   1b, 4b\n"                               \
 543         "       .long   2b, 4b\n"                               \
 544         "       .popsection"                                    \
 545         : "+r" (err), "+r" (__pu_addr)                          \
 546         : "r" (x), "i" (-EFAULT)                                \
 547         : "cc")
 548
 549 #endif /* !CONFIG_CPU_SPECTRE */
 550
 551 #ifdef CONFIG_MMU
 552 extern unsigned long __must_check
 553 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 554
 555 static inline unsigned long __must_check
 556 __copy_from_user(void *to, const void __user *from, unsigned long n)
 557 {
 558         unsigned int __ua_flags = uaccess_save_and_enable();
 559         n = arm_copy_from_user(to, from, n);
 560         uaccess_restore(__ua_flags);
 561         return n;
 562 }
 563
 564 extern unsigned long __must_check
 565 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 566 extern unsigned long __must_check
 567 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 568
 569 static inline unsigned long __must_check
 570 __copy_to_user(void __user *to, const void *from, unsigned long n)
 571 {
 572 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 573         unsigned int __ua_flags = uaccess_save_and_enable();
 574         n = arm_copy_to_user(to, from, n);
 575         uaccess_restore(__ua_flags);
 576         return n;
 577 #else
 578         return arm_copy_to_user(to, from, n);
 579 #endif
 580 }
 581
 582 extern unsigned long __must_check
 583 arm_clear_user(void __user *addr, unsigned long n);
 584 extern unsigned long __must_check
 585 __clear_user_std(void __user *addr, unsigned long n);
 586
 587 static inline unsigned long __must_check
 588 __clear_user(void __user *addr, unsigned long n)
 589 {
 590         unsigned int __ua_flags = uaccess_save_and_enable();
 591         n = arm_clear_user(addr, n);
 592         uaccess_restore(__ua_flags);
 593         return n;
 594 }
 595
 596 #else
 597 #define __copy_from_user(to, from, n)   (memcpy(to, (void __force *)from, n), 0)
 598 #define __copy_to_user(to, from, n)     (memcpy((void __force *)to, from, n), 0)
 599 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 600 #endif
 601
 602 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 603 {
 604         if (access_ok(VERIFY_READ, from, n))
 605                 n = __copy_from_user(to, from, n);
 606         else /* security hole - plug it */
 607                 memset(to, 0, n);
 608         return n;
 609 }
 610
 611 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 612 {
 613         if (access_ok(VERIFY_WRITE, to, n))
 614                 n = __copy_to_user(to, from, n);
 615         return n;
 616 }
 617
 618 #define __copy_to_user_inatomic __copy_to_user
 619 #define __copy_from_user_inatomic __copy_from_user
 620
 621 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 622 {
 623         if (access_ok(VERIFY_WRITE, to, n))
 624                 n = __clear_user(to, n);
 625         return n;
 626 }
 627
 628 /* These are from lib/ code, and use __get_user() and friends */
 629 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 630
 631 extern __must_check long strlen_user(const char __user *str);
 632 extern __must_check long strnlen_user(const char __user *str, long n);
 633
 634 #endif /* _ASMARM_UACCESS_H */