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 are intentionally not defined anywhere - if the kernel
  54  * code generates any references to them, that's a bug.
  55  */
  56 extern int __get_user_bad(void);
  57 extern int __put_user_bad(void);
  58
  59 /*
  60  * Note that this is actually 0x1,0000,0000
  61  */
  62 #define KERNEL_DS       0x00000000
  63 #define get_ds()        (KERNEL_DS)
  64
  65 #ifdef CONFIG_MMU
  66
  67 #define USER_DS         TASK_SIZE
  68 #define get_fs()        (current_thread_info()->addr_limit)
  69
  70 static inline void set_fs(mm_segment_t fs)
  71 {
  72         current_thread_info()->addr_limit = fs;
  73         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
  74 }
  75
  76 #define segment_eq(a,b) ((a) == (b))
  77
  78 #define __addr_ok(addr) ({ \
  79         unsigned long flag; \
  80         __asm__("cmp %2, %0; movlo %0, #0" \
  81                 : "=&r" (flag) \
  82                 : "0" (current_thread_info()->addr_limit), "r" (addr) \
  83                 : "cc"); \
  84         (flag == 0); })
  85
  86 /* We use 33-bit arithmetic here... */
  87 #define __range_ok(addr,size) ({ \
  88         unsigned long flag, roksum; \
  89         __chk_user_ptr(addr);   \
  90         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
  91                 : "=&r" (flag), "=&r" (roksum) \
  92                 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
  93                 : "cc"); \
  94         flag; })
  95
  96 /*
  97  * Single-value transfer routines.  They automatically use the right
  98  * size if we just have the right pointer type.  Note that the functions
  99  * which read from user space (*get_*) need to take care not to leak
 100  * kernel data even if the calling code is buggy and fails to check
 101  * the return value.  This means zeroing out the destination variable
 102  * or buffer on error.  Normally this is done out of line by the
 103  * fixup code, but there are a few places where it intrudes on the
 104  * main code path.  When we only write to user space, there is no
 105  * problem.
 106  */
 107 extern int __get_user_1(void *);
 108 extern int __get_user_2(void *);
 109 extern int __get_user_4(void *);
 110
 111 #define __GUP_CLOBBER_1 "lr", "cc"
 112 #ifdef CONFIG_CPU_USE_DOMAINS
 113 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
 114 #else
 115 #define __GUP_CLOBBER_2 "lr", "cc"
 116 #endif
 117 #define __GUP_CLOBBER_4 "lr", "cc"
 118
 119 #define __get_user_x(__r2,__p,__e,__l,__s)                              \
 120            __asm__ __volatile__ (                                       \
 121                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 122                 __asmeq("%3", "r1")                                     \
 123                 "bl     __get_user_" #__s                               \
 124                 : "=&r" (__e), "=r" (__r2)                              \
 125                 : "0" (__p), "r" (__l)                                  \
 126                 : __GUP_CLOBBER_##__s)
 127
 128 #define __get_user_check(x,p)                                                   \
 129         ({                                                              \
 130                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 131                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 132                 register unsigned long __r2 asm("r2");                  \
 133                 register unsigned long __l asm("r1") = __limit;         \
 134                 register int __e asm("r0");                             \
 135                 switch (sizeof(*(__p))) {                               \
 136                 case 1:                                                 \
 137                         __get_user_x(__r2, __p, __e, __l, 1);           \
 138                         break;                                          \
 139                 case 2:                                                 \
 140                         __get_user_x(__r2, __p, __e, __l, 2);           \
 141                         break;                                          \
 142                 case 4:                                                 \
 143                         __get_user_x(__r2, __p, __e, __l, 4);           \
 144                         break;                                          \
 145                 default: __e = __get_user_bad(); break;                 \
 146                 }                                                       \
 147                 x = (typeof(*(p))) __r2;                                \
 148                 __e;                                                    \
 149         })
 150
 151 #define get_user(x,p)                                                   \
 152         ({                                                              \
 153                 might_fault();                                          \
 154                 __get_user_check(x,p);                                  \
 155          })
 156
 157 extern int __put_user_1(void *, unsigned int);
 158 extern int __put_user_2(void *, unsigned int);
 159 extern int __put_user_4(void *, unsigned int);
 160 extern int __put_user_8(void *, unsigned long long);
 161
 162 #define __put_user_x(__r2,__p,__e,__l,__s)                              \
 163            __asm__ __volatile__ (                                       \
 164                 __asmeq("%0", "r0") __asmeq("%2", "r2")                 \
 165                 __asmeq("%3", "r1")                                     \
 166                 "bl     __put_user_" #__s                               \
 167                 : "=&r" (__e)                                           \
 168                 : "0" (__p), "r" (__r2), "r" (__l)                      \
 169                 : "ip", "lr", "cc")
 170
 171 #define __put_user_check(x,p)                                                   \
 172         ({                                                              \
 173                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 174                 const typeof(*(p)) __user *__tmp_p = (p);               \
 175                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
 176                 register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
 177                 register unsigned long __l asm("r1") = __limit;         \
 178                 register int __e asm("r0");                             \
 179                 switch (sizeof(*(__p))) {                               \
 180                 case 1:                                                 \
 181                         __put_user_x(__r2, __p, __e, __l, 1);           \
 182                         break;                                          \
 183                 case 2:                                                 \
 184                         __put_user_x(__r2, __p, __e, __l, 2);           \
 185                         break;                                          \
 186                 case 4:                                                 \
 187                         __put_user_x(__r2, __p, __e, __l, 4);           \
 188                         break;                                          \
 189                 case 8:                                                 \
 190                         __put_user_x(__r2, __p, __e, __l, 8);           \
 191                         break;                                          \
 192                 default: __e = __put_user_bad(); break;                 \
 193                 }                                                       \
 194                 __e;                                                    \
 195         })
 196
 197 #define put_user(x,p)                                                   \
 198         ({                                                              \
 199                 might_fault();                                          \
 200                 __put_user_check(x,p);                                  \
 201          })
 202
 203 #else /* CONFIG_MMU */
 204
 205 /*
 206  * uClinux has only one addr space, so has simplified address limits.
 207  */
 208 #define USER_DS                 KERNEL_DS
 209
 210 #define segment_eq(a,b)         (1)
 211 #define __addr_ok(addr)         ((void)(addr),1)
 212 #define __range_ok(addr,size)   ((void)(addr),0)
 213 #define get_fs()                (KERNEL_DS)
 214
 215 static inline void set_fs(mm_segment_t fs)
 216 {
 217 }
 218
 219 #define get_user(x,p)   __get_user(x,p)
 220 #define put_user(x,p)   __put_user(x,p)
 221
 222 #endif /* CONFIG_MMU */
 223
 224 #define access_ok(type,addr,size)       (__range_ok(addr,size) == 0)
 225
 226 #define user_addr_max() \
 227         (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
 228
 229 /*
 230  * The "__xxx" versions of the user access functions do not verify the
 231  * address space - it must have been done previously with a separate
 232  * "access_ok()" call.
 233  *
 234  * The "xxx_error" versions set the third argument to EFAULT if an
 235  * error occurs, and leave it unchanged on success.  Note that these
 236  * versions are void (ie, don't return a value as such).
 237  */
 238 #define __get_user(x,ptr)                                               \
 239 ({                                                                      \
 240         long __gu_err = 0;                                              \
 241         __get_user_err((x),(ptr),__gu_err);                             \
 242         __gu_err;                                                       \
 243 })
 244
 245 #define __get_user_error(x,ptr,err)                                     \
 246 ({                                                                      \
 247         __get_user_err((x),(ptr),err);                                  \
 248         (void) 0;                                                       \
 249 })
 250
 251 #define __get_user_err(x,ptr,err)                                       \
 252 do {                                                                    \
 253         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 254         unsigned long __gu_val;                                         \
 255         __chk_user_ptr(ptr);                                            \
 256         might_fault();                                                  \
 257         switch (sizeof(*(ptr))) {                                       \
 258         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
 259         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
 260         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
 261         default: (__gu_val) = __get_user_bad();                         \
 262         }                                                               \
 263         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 264 } while (0)
 265
 266 #define __get_user_asm_byte(x,addr,err)                         \
 267         __asm__ __volatile__(                                   \
 268         "1:     " TUSER(ldrb) " %1,[%2],#0\n"                   \
 269         "2:\n"                                                  \
 270         "       .pushsection .fixup,\"ax\"\n"                   \
 271         "       .align  2\n"                                    \
 272         "3:     mov     %0, %3\n"                               \
 273         "       mov     %1, #0\n"                               \
 274         "       b       2b\n"                                   \
 275         "       .popsection\n"                                  \
 276         "       .pushsection __ex_table,\"a\"\n"                \
 277         "       .align  3\n"                                    \
 278         "       .long   1b, 3b\n"                               \
 279         "       .popsection"                                    \
 280         : "+r" (err), "=&r" (x)                                 \
 281         : "r" (addr), "i" (-EFAULT)                             \
 282         : "cc")
 283
 284 #ifndef __ARMEB__
 285 #define __get_user_asm_half(x,__gu_addr,err)                    \
 286 ({                                                              \
 287         unsigned long __b1, __b2;                               \
 288         __get_user_asm_byte(__b1, __gu_addr, err);              \
 289         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 290         (x) = __b1 | (__b2 << 8);                               \
 291 })
 292 #else
 293 #define __get_user_asm_half(x,__gu_addr,err)                    \
 294 ({                                                              \
 295         unsigned long __b1, __b2;                               \
 296         __get_user_asm_byte(__b1, __gu_addr, err);              \
 297         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 298         (x) = (__b1 << 8) | __b2;                               \
 299 })
 300 #endif
 301
 302 #define __get_user_asm_word(x,addr,err)                         \
 303         __asm__ __volatile__(                                   \
 304         "1:     " TUSER(ldr) "  %1,[%2],#0\n"                   \
 305         "2:\n"                                                  \
 306         "       .pushsection .fixup,\"ax\"\n"                   \
 307         "       .align  2\n"                                    \
 308         "3:     mov     %0, %3\n"                               \
 309         "       mov     %1, #0\n"                               \
 310         "       b       2b\n"                                   \
 311         "       .popsection\n"                                  \
 312         "       .pushsection __ex_table,\"a\"\n"                \
 313         "       .align  3\n"                                    \
 314         "       .long   1b, 3b\n"                               \
 315         "       .popsection"                                    \
 316         : "+r" (err), "=&r" (x)                                 \
 317         : "r" (addr), "i" (-EFAULT)                             \
 318         : "cc")
 319
 320 #define __put_user(x,ptr)                                               \
 321 ({                                                                      \
 322         long __pu_err = 0;                                              \
 323         __put_user_err((x),(ptr),__pu_err);                             \
 324         __pu_err;                                                       \
 325 })
 326
 327 #define __put_user_error(x,ptr,err)                                     \
 328 ({                                                                      \
 329         __put_user_err((x),(ptr),err);                                  \
 330         (void) 0;                                                       \
 331 })
 332
 333 #define __put_user_err(x,ptr,err)                                       \
 334 do {                                                                    \
 335         unsigned long __pu_addr = (unsigned long)(ptr);                 \
 336         __typeof__(*(ptr)) __pu_val = (x);                              \
 337         __chk_user_ptr(ptr);                                            \
 338         might_fault();                                                  \
 339         switch (sizeof(*(ptr))) {                                       \
 340         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
 341         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
 342         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
 343         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
 344         default: __put_user_bad();                                      \
 345         }                                                               \
 346 } while (0)
 347
 348 #define __put_user_asm_byte(x,__pu_addr,err)                    \
 349         __asm__ __volatile__(                                   \
 350         "1:     " TUSER(strb) " %1,[%2],#0\n"                   \
 351         "2:\n"                                                  \
 352         "       .pushsection .fixup,\"ax\"\n"                   \
 353         "       .align  2\n"                                    \
 354         "3:     mov     %0, %3\n"                               \
 355         "       b       2b\n"                                   \
 356         "       .popsection\n"                                  \
 357         "       .pushsection __ex_table,\"a\"\n"                \
 358         "       .align  3\n"                                    \
 359         "       .long   1b, 3b\n"                               \
 360         "       .popsection"                                    \
 361         : "+r" (err)                                            \
 362         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 363         : "cc")
 364
 365 #ifndef __ARMEB__
 366 #define __put_user_asm_half(x,__pu_addr,err)                    \
 367 ({                                                              \
 368         unsigned long __temp = (unsigned long)(x);              \
 369         __put_user_asm_byte(__temp, __pu_addr, err);            \
 370         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 371 })
 372 #else
 373 #define __put_user_asm_half(x,__pu_addr,err)                    \
 374 ({                                                              \
 375         unsigned long __temp = (unsigned long)(x);              \
 376         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 377         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 378 })
 379 #endif
 380
 381 #define __put_user_asm_word(x,__pu_addr,err)                    \
 382         __asm__ __volatile__(                                   \
 383         "1:     " TUSER(str) "  %1,[%2],#0\n"                   \
 384         "2:\n"                                                  \
 385         "       .pushsection .fixup,\"ax\"\n"                   \
 386         "       .align  2\n"                                    \
 387         "3:     mov     %0, %3\n"                               \
 388         "       b       2b\n"                                   \
 389         "       .popsection\n"                                  \
 390         "       .pushsection __ex_table,\"a\"\n"                \
 391         "       .align  3\n"                                    \
 392         "       .long   1b, 3b\n"                               \
 393         "       .popsection"                                    \
 394         : "+r" (err)                                            \
 395         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 396         : "cc")
 397
 398 #ifndef __ARMEB__
 399 #define __reg_oper0     "%R2"
 400 #define __reg_oper1     "%Q2"
 401 #else
 402 #define __reg_oper0     "%Q2"
 403 #define __reg_oper1     "%R2"
 404 #endif
 405
 406 #define __put_user_asm_dword(x,__pu_addr,err)                   \
 407         __asm__ __volatile__(                                   \
 408  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 409  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 410  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 411  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 412         "3:\n"                                                  \
 413         "       .pushsection .fixup,\"ax\"\n"                   \
 414         "       .align  2\n"                                    \
 415         "4:     mov     %0, %3\n"                               \
 416         "       b       3b\n"                                   \
 417         "       .popsection\n"                                  \
 418         "       .pushsection __ex_table,\"a\"\n"                \
 419         "       .align  3\n"                                    \
 420         "       .long   1b, 4b\n"                               \
 421         "       .long   2b, 4b\n"                               \
 422         "       .popsection"                                    \
 423         : "+r" (err), "+r" (__pu_addr)                          \
 424         : "r" (x), "i" (-EFAULT)                                \
 425         : "cc")
 426
 427
 428 #ifdef CONFIG_MMU
 429 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 430 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 431 extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 432 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 433 extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
 434 #else
 435 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
 436 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
 437 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
 438 #endif
 439
 440 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 441 {
 442         if (access_ok(VERIFY_READ, from, n))
 443                 n = __copy_from_user(to, from, n);
 444         else /* security hole - plug it */
 445                 memset(to, 0, n);
 446         return n;
 447 }
 448
 449 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 450 {
 451         if (access_ok(VERIFY_WRITE, to, n))
 452                 n = __copy_to_user(to, from, n);
 453         return n;
 454 }
 455
 456 #define __copy_to_user_inatomic __copy_to_user
 457 #define __copy_from_user_inatomic __copy_from_user
 458
 459 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 460 {
 461         if (access_ok(VERIFY_WRITE, to, n))
 462                 n = __clear_user(to, n);
 463         return n;
 464 }
 465
 466 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 467
 468 extern __must_check long strlen_user(const char __user *str);
 469 extern __must_check long strnlen_user(const char __user *str, long n);
 470
 471 #endif /* _ASMARM_UACCESS_H */