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 /* We use 33-bit arithmetic here... */
 116 #define __range_ok(addr, size) ({ \
 117         unsigned long flag, roksum; \
 118         __chk_user_ptr(addr);   \
 119         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
 120                 : "=&r" (flag), "=&r" (roksum) \
 121                 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
 122                 : "cc"); \
 123         flag; })
 124
 125 /*
 126  * This is a type: either unsigned long, if the argument fits into
 127  * that type, or otherwise unsigned long long.
 128  */
 129 #define __inttype(x) \
 130         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 131
 132 /*
 133  * Sanitise a uaccess pointer such that it becomes NULL if addr+size
 134  * is above the current addr_limit.
 135  */
 136 #define uaccess_mask_range_ptr(ptr, size)                       \
 137         ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
 138 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
 139                                                     size_t size)
 140 {
 141         void __user *safe_ptr = (void __user *)ptr;
 142         unsigned long tmp;
 143
 144         asm volatile(
 145         "       sub     %1, %3, #1\n"
 146         "       subs    %1, %1, %0\n"
 147         "       addhs   %1, %1, #1\n"
 148         "       subhss  %1, %1, %2\n"
 149         "       movlo   %0, #0\n"
 150         : "+r" (safe_ptr), "=&r" (tmp)
 151         : "r" (size), "r" (current_thread_info()->addr_limit)
 152         : "cc");
 153
 154         csdb();
 155         return safe_ptr;
 156 }
 157
 158 /*
 159  * Single-value transfer routines.  They automatically use the right
 160  * size if we just have the right pointer type.  Note that the functions
 161  * which read from user space (*get_*) need to take care not to leak
 162  * kernel data even if the calling code is buggy and fails to check
 163  * the return value.  This means zeroing out the destination variable
 164  * or buffer on error.  Normally this is done out of line by the
 165  * fixup code, but there are a few places where it intrudes on the
 166  * main code path.  When we only write to user space, there is no
 167  * problem.
 168  */
 169 extern int __get_user_1(void *);
 170 extern int __get_user_2(void *);
 171 extern int __get_user_4(void *);
 172 extern int __get_user_32t_8(void *);
 173 extern int __get_user_8(void *);
 174 extern int __get_user_64t_1(void *);
 175 extern int __get_user_64t_2(void *);
 176 extern int __get_user_64t_4(void *);
 177
 178 #define __GUP_CLOBBER_1 "lr", "cc"
 179 #ifdef CONFIG_CPU_USE_DOMAINS
 180 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
 181 #else
 182 #define __GUP_CLOBBER_2 "lr", "cc"
 183 #endif
 184 #define __GUP_CLOBBER_4 "lr", "cc"
 185 #define __GUP_CLOBBER_32t_8 "lr", "cc"
 186 #define __GUP_CLOBBER_8 "lr", "cc"
 187
 188 #define __get_user_x(__r2, __p, __e, __l, __s)                          \
 189            __asm__ __volatile__ (                                       \
 190                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 191                 __asmeq("%3", "r1")                                     \
 192                 "bl     __get_user_" #__s                               \
 193                 : "=&r" (__e), "=r" (__r2)                              \
 194                 : "0" (__p), "r" (__l)                                  \
 195                 : __GUP_CLOBBER_##__s)
 196
 197 /* narrowing a double-word get into a single 32bit word register: */
 198 #ifdef __ARMEB__
 199 #define __get_user_x_32t(__r2, __p, __e, __l, __s)                      \
 200         __get_user_x(__r2, __p, __e, __l, 32t_8)
 201 #else
 202 #define __get_user_x_32t __get_user_x
 203 #endif
 204
 205 /*
 206  * storing result into proper least significant word of 64bit target var,
 207  * different only for big endian case where 64 bit __r2 lsw is r3:
 208  */
 209 #ifdef __ARMEB__
 210 #define __get_user_x_64t(__r2, __p, __e, __l, __s)                      \
 211            __asm__ __volatile__ (                                       \
 212                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 213                 __asmeq("%3", "r1")                                     \
 214                 "bl     __get_user_64t_" #__s                           \
 215                 : "=&r" (__e), "=r" (__r2)                              \
 216                 : "0" (__p), "r" (__l)                                  \
 217                 : __GUP_CLOBBER_##__s)
 218 #else
 219 #define __get_user_x_64t __get_user_x
 220 #endif
 221
 222
 223 #define __get_user_check(x, p)                                          \
 224         ({                                                              \
 225                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 226                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 227                 register __inttype(x) __r2 asm("r2");                   \
 228                 register unsigned long __l asm("r1") = __limit;         \
 229                 register int __e asm("r0");                             \
 230                 unsigned int __ua_flags = uaccess_save_and_enable();    \
 231                 switch (sizeof(*(__p))) {                               \
 232                 case 1:                                                 \
 233                         if (sizeof((x)) >= 8)                           \
 234                                 __get_user_x_64t(__r2, __p, __e, __l, 1); \
 235                         else                                            \
 236                                 __get_user_x(__r2, __p, __e, __l, 1);   \
 237                         break;                                          \
 238                 case 2:                                                 \
 239                         if (sizeof((x)) >= 8)                           \
 240                                 __get_user_x_64t(__r2, __p, __e, __l, 2); \
 241                         else                                            \
 242                                 __get_user_x(__r2, __p, __e, __l, 2);   \
 243                         break;                                          \
 244                 case 4:                                                 \
 245                         if (sizeof((x)) >= 8)                           \
 246                                 __get_user_x_64t(__r2, __p, __e, __l, 4); \
 247                         else                                            \
 248                                 __get_user_x(__r2, __p, __e, __l, 4);   \
 249                         break;                                          \
 250                 case 8:                                                 \
 251                         if (sizeof((x)) < 8)                            \
 252                                 __get_user_x_32t(__r2, __p, __e, __l, 4); \
 253                         else                                            \
 254                                 __get_user_x(__r2, __p, __e, __l, 8);   \
 255                         break;                                          \
 256                 default: __e = __get_user_bad(); break;                 \
 257                 }                                                       \
 258                 uaccess_restore(__ua_flags);                            \
 259                 x = (typeof(*(p))) __r2;                                \
 260                 __e;                                                    \
 261         })
 262
 263 #define get_user(x, p)                                                  \
 264         ({                                                              \
 265                 might_fault();                                          \
 266                 __get_user_check(x, p);                                 \
 267          })
 268
 269 extern int __put_user_1(void *, unsigned int);
 270 extern int __put_user_2(void *, unsigned int);
 271 extern int __put_user_4(void *, unsigned int);
 272 extern int __put_user_8(void *, unsigned long long);
 273
 274 #define __put_user_check(__pu_val, __ptr, __err, __s)                   \
 275         ({                                                              \
 276                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 277                 register typeof(__pu_val) __r2 asm("r2") = __pu_val;    \
 278                 register const void __user *__p asm("r0") = __ptr;      \
 279                 register unsigned long __l asm("r1") = __limit;         \
 280                 register int __e asm("r0");                             \
 281                 __asm__ __volatile__ (                                  \
 282                         __asmeq("%0", "r0") __asmeq("%2", "r2")         \
 283                         __asmeq("%3", "r1")                             \
 284                         "bl     __put_user_" #__s                       \
 285                         : "=&r" (__e)                                   \
 286                         : "0" (__p), "r" (__r2), "r" (__l)              \
 287                         : "ip", "lr", "cc");                            \
 288                 __err = __e;                                            \
 289         })
 290
 291 #else /* CONFIG_MMU */
 292
 293 /*
 294  * uClinux has only one addr space, so has simplified address limits.
 295  */
 296 #define USER_DS                 KERNEL_DS
 297
 298 #define segment_eq(a, b)                (1)
 299 #define __addr_ok(addr)         ((void)(addr), 1)
 300 #define __range_ok(addr, size)  ((void)(addr), 0)
 301 #define get_fs()                (KERNEL_DS)
 302
 303 static inline void set_fs(mm_segment_t fs)
 304 {
 305 }
 306
 307 #define get_user(x, p)  __get_user(x, p)
 308 #define __put_user_check __put_user_nocheck
 309
 310 #endif /* CONFIG_MMU */
 311
 312 #define access_ok(type, addr, size)     (__range_ok(addr, size) == 0)
 313
 314 #define user_addr_max() \
 315         (segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs())
 316
 317 #ifdef CONFIG_CPU_SPECTRE
 318 /*
 319  * When mitigating Spectre variant 1, it is not worth fixing the non-
 320  * verifying accessors, because we need to add verification of the
 321  * address space there.  Force these to use the standard get_user()
 322  * version instead.
 323  */
 324 #define __get_user(x, ptr) get_user(x, ptr)
 325 #else
 326
 327 /*
 328  * The "__xxx" versions of the user access functions do not verify the
 329  * address space - it must have been done previously with a separate
 330  * "access_ok()" call.
 331  *
 332  * The "xxx_error" versions set the third argument to EFAULT if an
 333  * error occurs, and leave it unchanged on success.  Note that these
 334  * versions are void (ie, don't return a value as such).
 335  */
 336 #define __get_user(x, ptr)                                              \
 337 ({                                                                      \
 338         long __gu_err = 0;                                              \
 339         __get_user_err((x), (ptr), __gu_err);                           \
 340         __gu_err;                                                       \
 341 })
 342
 343 #define __get_user_err(x, ptr, err)                                     \
 344 do {                                                                    \
 345         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 346         unsigned long __gu_val;                                         \
 347         unsigned int __ua_flags;                                        \
 348         __chk_user_ptr(ptr);                                            \
 349         might_fault();                                                  \
 350         __ua_flags = uaccess_save_and_enable();                         \
 351         switch (sizeof(*(ptr))) {                                       \
 352         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err);  break;  \
 353         case 2: __get_user_asm_half(__gu_val, __gu_addr, err);  break;  \
 354         case 4: __get_user_asm_word(__gu_val, __gu_addr, err);  break;  \
 355         default: (__gu_val) = __get_user_bad();                         \
 356         }                                                               \
 357         uaccess_restore(__ua_flags);                                    \
 358         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 359 } while (0)
 360
 361 #define __get_user_asm(x, addr, err, instr)                     \
 362         __asm__ __volatile__(                                   \
 363         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 364         "2:\n"                                                  \
 365         "       .pushsection .text.fixup,\"ax\"\n"              \
 366         "       .align  2\n"                                    \
 367         "3:     mov     %0, %3\n"                               \
 368         "       mov     %1, #0\n"                               \
 369         "       b       2b\n"                                   \
 370         "       .popsection\n"                                  \
 371         "       .pushsection __ex_table,\"a\"\n"                \
 372         "       .align  3\n"                                    \
 373         "       .long   1b, 3b\n"                               \
 374         "       .popsection"                                    \
 375         : "+r" (err), "=&r" (x)                                 \
 376         : "r" (addr), "i" (-EFAULT)                             \
 377         : "cc")
 378
 379 #define __get_user_asm_byte(x, addr, err)                       \
 380         __get_user_asm(x, addr, err, ldrb)
 381
 382 #if __LINUX_ARM_ARCH__ >= 6
 383
 384 #define __get_user_asm_half(x, addr, err)                       \
 385         __get_user_asm(x, addr, err, ldrh)
 386
 387 #else
 388
 389 #ifndef __ARMEB__
 390 #define __get_user_asm_half(x, __gu_addr, err)                  \
 391 ({                                                              \
 392         unsigned long __b1, __b2;                               \
 393         __get_user_asm_byte(__b1, __gu_addr, err);              \
 394         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 395         (x) = __b1 | (__b2 << 8);                               \
 396 })
 397 #else
 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 << 8) | __b2;                               \
 404 })
 405 #endif
 406
 407 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 408
 409 #define __get_user_asm_word(x, addr, err)                       \
 410         __get_user_asm(x, addr, err, ldr)
 411 #endif
 412
 413
 414 #define __put_user_switch(x, ptr, __err, __fn)                          \
 415         do {                                                            \
 416                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 417                 __typeof__(*(ptr)) __pu_val = (x);                      \
 418                 unsigned int __ua_flags;                                \
 419                 might_fault();                                          \
 420                 __ua_flags = uaccess_save_and_enable();                 \
 421                 switch (sizeof(*(ptr))) {                               \
 422                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 423                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 424                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 425                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 426                 default: __err = __put_user_bad(); break;               \
 427                 }                                                       \
 428                 uaccess_restore(__ua_flags);                            \
 429         } while (0)
 430
 431 #define put_user(x, ptr)                                                \
 432 ({                                                                      \
 433         int __pu_err = 0;                                               \
 434         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 435         __pu_err;                                                       \
 436 })
 437
 438 #ifdef CONFIG_CPU_SPECTRE
 439 /*
 440  * When mitigating Spectre variant 1.1, all accessors need to include
 441  * verification of the address space.
 442  */
 443 #define __put_user(x, ptr) put_user(x, ptr)
 444
 445 #else
 446 #define __put_user(x, ptr)                                              \
 447 ({                                                                      \
 448         long __pu_err = 0;                                              \
 449         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 450         __pu_err;                                                       \
 451 })
 452
 453 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 454         do {                                                            \
 455                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 456                 __put_user_nocheck_##__size(x, __pu_addr, __err);       \
 457         } while (0)
 458
 459 #define __put_user_nocheck_1 __put_user_asm_byte
 460 #define __put_user_nocheck_2 __put_user_asm_half
 461 #define __put_user_nocheck_4 __put_user_asm_word
 462 #define __put_user_nocheck_8 __put_user_asm_dword
 463
 464 #define __put_user_asm(x, __pu_addr, err, instr)                \
 465         __asm__ __volatile__(                                   \
 466         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 467         "2:\n"                                                  \
 468         "       .pushsection .text.fixup,\"ax\"\n"              \
 469         "       .align  2\n"                                    \
 470         "3:     mov     %0, %3\n"                               \
 471         "       b       2b\n"                                   \
 472         "       .popsection\n"                                  \
 473         "       .pushsection __ex_table,\"a\"\n"                \
 474         "       .align  3\n"                                    \
 475         "       .long   1b, 3b\n"                               \
 476         "       .popsection"                                    \
 477         : "+r" (err)                                            \
 478         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 479         : "cc")
 480
 481 #define __put_user_asm_byte(x, __pu_addr, err)                  \
 482         __put_user_asm(x, __pu_addr, err, strb)
 483
 484 #if __LINUX_ARM_ARCH__ >= 6
 485
 486 #define __put_user_asm_half(x, __pu_addr, err)                  \
 487         __put_user_asm(x, __pu_addr, err, strh)
 488
 489 #else
 490
 491 #ifndef __ARMEB__
 492 #define __put_user_asm_half(x, __pu_addr, err)                  \
 493 ({                                                              \
 494         unsigned long __temp = (__force unsigned long)(x);      \
 495         __put_user_asm_byte(__temp, __pu_addr, err);            \
 496         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 497 })
 498 #else
 499 #define __put_user_asm_half(x, __pu_addr, err)                  \
 500 ({                                                              \
 501         unsigned long __temp = (__force unsigned long)(x);      \
 502         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 503         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 504 })
 505 #endif
 506
 507 #endif /* __LINUX_ARM_ARCH__ >= 6 */
 508
 509 #define __put_user_asm_word(x, __pu_addr, err)                  \
 510         __put_user_asm(x, __pu_addr, err, str)
 511
 512 #ifndef __ARMEB__
 513 #define __reg_oper0     "%R2"
 514 #define __reg_oper1     "%Q2"
 515 #else
 516 #define __reg_oper0     "%Q2"
 517 #define __reg_oper1     "%R2"
 518 #endif
 519
 520 #define __put_user_asm_dword(x, __pu_addr, err)                 \
 521         __asm__ __volatile__(                                   \
 522  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 523  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 524  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 525  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 526         "3:\n"                                                  \
 527         "       .pushsection .text.fixup,\"ax\"\n"              \
 528         "       .align  2\n"                                    \
 529         "4:     mov     %0, %3\n"                               \
 530         "       b       3b\n"                                   \
 531         "       .popsection\n"                                  \
 532         "       .pushsection __ex_table,\"a\"\n"                \
 533         "       .align  3\n"                                    \
 534         "       .long   1b, 4b\n"                               \
 535         "       .long   2b, 4b\n"                               \
 536         "       .popsection"                                    \
 537         : "+r" (err), "+r" (__pu_addr)                          \
 538         : "r" (x), "i" (-EFAULT)                                \
 539         : "cc")
 540
 541 #endif /* !CONFIG_CPU_SPECTRE */
 542
 543 #ifdef CONFIG_MMU
 544 extern unsigned long __must_check
 545 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 546
 547 static inline unsigned long __must_check
 548 __arch_copy_from_user(void *to, const void __user *from, unsigned long n)
 549 {
 550         unsigned int __ua_flags;
 551
 552         __ua_flags = uaccess_save_and_enable();
 553         n = arm_copy_from_user(to, from, n);
 554         uaccess_restore(__ua_flags);
 555         return n;
 556 }
 557
 558 extern unsigned long __must_check
 559 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 560 extern unsigned long __must_check
 561 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 562
 563 static inline unsigned long __must_check
 564 __arch_copy_to_user(void __user *to, const void *from, unsigned long n)
 565 {
 566 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 567         unsigned int __ua_flags;
 568         __ua_flags = uaccess_save_and_enable();
 569         n = arm_copy_to_user(to, from, n);
 570         uaccess_restore(__ua_flags);
 571         return n;
 572 #else
 573         return arm_copy_to_user(to, from, n);
 574 #endif
 575 }
 576
 577 extern unsigned long __must_check
 578 arm_clear_user(void __user *addr, unsigned long n);
 579 extern unsigned long __must_check
 580 __clear_user_std(void __user *addr, unsigned long n);
 581
 582 static inline unsigned long __must_check
 583 __clear_user(void __user *addr, unsigned long n)
 584 {
 585         unsigned int __ua_flags = uaccess_save_and_enable();
 586         n = arm_clear_user(addr, n);
 587         uaccess_restore(__ua_flags);
 588         return n;
 589 }
 590
 591 #else
 592 #define __arch_copy_from_user(to, from, n)      \
 593                                         (memcpy(to, (void __force *)from, n), 0)
 594 #define __arch_copy_to_user(to, from, n)        \
 595                                         (memcpy((void __force *)to, from, n), 0)
 596 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 597 #endif
 598
 599 static inline unsigned long __must_check
 600 __copy_from_user(void *to, const void __user *from, unsigned long n)
 601 {
 602         check_object_size(to, n, false);
 603         return __arch_copy_from_user(to, from, n);
 604 }
 605
 606 static inline unsigned long __must_check
 607 copy_from_user(void *to, const void __user *from, unsigned long n)
 608 {
 609         unsigned long res = n;
 610
 611         check_object_size(to, n, false);
 612
 613         if (likely(access_ok(VERIFY_READ, from, n)))
 614                 res = __arch_copy_from_user(to, from, n);
 615         if (unlikely(res))
 616                 memset(to + (n - res), 0, res);
 617         return res;
 618 }
 619
 620 static inline unsigned long __must_check
 621 __copy_to_user(void __user *to, const void *from, unsigned long n)
 622 {
 623         check_object_size(from, n, true);
 624
 625         return __arch_copy_to_user(to, from, n);
 626 }
 627
 628 static inline unsigned long __must_check
 629 copy_to_user(void __user *to, const void *from, unsigned long n)
 630 {
 631         check_object_size(from, n, true);
 632
 633         if (access_ok(VERIFY_WRITE, to, n))
 634                 n = __arch_copy_to_user(to, from, n);
 635         return n;
 636 }
 637
 638 #define __copy_to_user_inatomic __copy_to_user
 639 #define __copy_from_user_inatomic __copy_from_user
 640
 641 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 642 {
 643         if (access_ok(VERIFY_WRITE, to, n))
 644                 n = __clear_user(to, n);
 645         return n;
 646 }
 647
 648 /* These are from lib/ code, and use __get_user() and friends */
 649 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 650
 651 extern __must_check long strlen_user(const char __user *str);
 652 extern __must_check long strnlen_user(const char __user *str, long n);
 653
 654 #endif /* _ASMARM_UACCESS_H */