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   1 /*
   2  *  linux/include/asm-arm/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/sched.h>
  15 #include <asm/errno.h>
  16 #include <asm/memory.h>
  17 #include <asm/domain.h>
  18 #include <asm/system.h>
  19
  20 #define VERIFY_READ 0
  21 #define VERIFY_WRITE 1
  22
  23 /*
  24  * The exception table consists of pairs of addresses: the first is the
  25  * address of an instruction that is allowed to fault, and the second is
  26  * the address at which the program should continue.  No registers are
  27  * modified, so it is entirely up to the continuation code to figure out
  28  * what to do.
  29  *
  30  * All the routines below use bits of fixup code that are out of line
  31  * with the main instruction path.  This means when everything is well,
  32  * we don't even have to jump over them.  Further, they do not intrude
  33  * on our cache or tlb entries.
  34  */
  35
  36 struct exception_table_entry
  37 {
  38         unsigned long insn, fixup;
  39 };
  40
  41 extern int fixup_exception(struct pt_regs *regs);
  42
  43 /*
  44  * These two are intentionally not defined anywhere - if the kernel
  45  * code generates any references to them, that's a bug.
  46  */
  47 extern int __get_user_bad(void);
  48 extern int __put_user_bad(void);
  49
  50 /*
  51  * Note that this is actually 0x1,0000,0000
  52  */
  53 #define KERNEL_DS       0x00000000
  54 #define get_ds()        (KERNEL_DS)
  55
  56 #ifdef CONFIG_MMU
  57
  58 #define USER_DS         TASK_SIZE
  59 #define get_fs()        (current_thread_info()->addr_limit)
  60
  61 static inline void set_fs(mm_segment_t fs)
  62 {
  63         current_thread_info()->addr_limit = fs;
  64         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
  65 }
  66
  67 #define segment_eq(a,b) ((a) == (b))
  68
  69 #define __addr_ok(addr) ({ \
  70         unsigned long flag; \
  71         __asm__("cmp %2, %0; movlo %0, #0" \
  72                 : "=&r" (flag) \
  73                 : "0" (current_thread_info()->addr_limit), "r" (addr) \
  74                 : "cc"); \
  75         (flag == 0); })
  76
  77 /* We use 33-bit arithmetic here... */
  78 #define __range_ok(addr,size) ({ \
  79         unsigned long flag, roksum; \
  80         __chk_user_ptr(addr);   \
  81         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
  82                 : "=&r" (flag), "=&r" (roksum) \
  83                 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
  84                 : "cc"); \
  85         flag; })
  86
  87 /*
  88  * Single-value transfer routines.  They automatically use the right
  89  * size if we just have the right pointer type.  Note that the functions
  90  * which read from user space (*get_*) need to take care not to leak
  91  * kernel data even if the calling code is buggy and fails to check
  92  * the return value.  This means zeroing out the destination variable
  93  * or buffer on error.  Normally this is done out of line by the
  94  * fixup code, but there are a few places where it intrudes on the
  95  * main code path.  When we only write to user space, there is no
  96  * problem.
  97  */
  98 extern int __get_user_1(void *);
  99 extern int __get_user_2(void *);
 100 extern int __get_user_4(void *);
 101
 102 #define __get_user_x(__r2,__p,__e,__s,__i...)                           \
 103            __asm__ __volatile__ (                                       \
 104                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 105                 "bl     __get_user_" #__s                               \
 106                 : "=&r" (__e), "=r" (__r2)                              \
 107                 : "0" (__p)                                             \
 108                 : __i, "cc")
 109
 110 #define get_user(x,p)                                                   \
 111         ({                                                              \
 112                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 113                 register unsigned long __r2 asm("r2");                  \
 114                 register int __e asm("r0");                             \
 115                 switch (sizeof(*(__p))) {                               \
 116                 case 1:                                                 \
 117                         __get_user_x(__r2, __p, __e, 1, "lr");          \
 118                         break;                                          \
 119                 case 2:                                                 \
 120                         __get_user_x(__r2, __p, __e, 2, "r3", "lr");    \
 121                         break;                                          \
 122                 case 4:                                                 \
 123                         __get_user_x(__r2, __p, __e, 4, "lr");          \
 124                         break;                                          \
 125                 default: __e = __get_user_bad(); break;                 \
 126                 }                                                       \
 127                 x = (typeof(*(p))) __r2;                                \
 128                 __e;                                                    \
 129         })
 130
 131 extern int __put_user_1(void *, unsigned int);
 132 extern int __put_user_2(void *, unsigned int);
 133 extern int __put_user_4(void *, unsigned int);
 134 extern int __put_user_8(void *, unsigned long long);
 135
 136 #define __put_user_x(__r2,__p,__e,__s)                                  \
 137            __asm__ __volatile__ (                                       \
 138                 __asmeq("%0", "r0") __asmeq("%2", "r2")                 \
 139                 "bl     __put_user_" #__s                               \
 140                 : "=&r" (__e)                                           \
 141                 : "0" (__p), "r" (__r2)                                 \
 142                 : "ip", "lr", "cc")
 143
 144 #define put_user(x,p)                                                   \
 145         ({                                                              \
 146                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
 147                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 148                 register int __e asm("r0");                             \
 149                 switch (sizeof(*(__p))) {                               \
 150                 case 1:                                                 \
 151                         __put_user_x(__r2, __p, __e, 1);                \
 152                         break;                                          \
 153                 case 2:                                                 \
 154                         __put_user_x(__r2, __p, __e, 2);                \
 155                         break;                                          \
 156                 case 4:                                                 \
 157                         __put_user_x(__r2, __p, __e, 4);                \
 158                         break;                                          \
 159                 case 8:                                                 \
 160                         __put_user_x(__r2, __p, __e, 8);                \
 161                         break;                                          \
 162                 default: __e = __put_user_bad(); break;                 \
 163                 }                                                       \
 164                 __e;                                                    \
 165         })
 166
 167 #else /* CONFIG_MMU */
 168
 169 /*
 170  * uClinux has only one addr space, so has simplified address limits.
 171  */
 172 #define USER_DS                 KERNEL_DS
 173
 174 #define segment_eq(a,b)         (1)
 175 #define __addr_ok(addr)         (1)
 176 #define __range_ok(addr,size)   (0)
 177 #define get_fs()                (KERNEL_DS)
 178
 179 static inline void set_fs(mm_segment_t fs)
 180 {
 181 }
 182
 183 #define get_user(x,p)   __get_user(x,p)
 184 #define put_user(x,p)   __put_user(x,p)
 185
 186 #endif /* CONFIG_MMU */
 187
 188 #define access_ok(type,addr,size)       (__range_ok(addr,size) == 0)
 189
 190 /*
 191  * The "__xxx" versions of the user access functions do not verify the
 192  * address space - it must have been done previously with a separate
 193  * "access_ok()" call.
 194  *
 195  * The "xxx_error" versions set the third argument to EFAULT if an
 196  * error occurs, and leave it unchanged on success.  Note that these
 197  * versions are void (ie, don't return a value as such).
 198  */
 199 #define __get_user(x,ptr)                                               \
 200 ({                                                                      \
 201         long __gu_err = 0;                                              \
 202         __get_user_err((x),(ptr),__gu_err);                             \
 203         __gu_err;                                                       \
 204 })
 205
 206 #define __get_user_error(x,ptr,err)                                     \
 207 ({                                                                      \
 208         __get_user_err((x),(ptr),err);                                  \
 209         (void) 0;                                                       \
 210 })
 211
 212 #define __get_user_err(x,ptr,err)                                       \
 213 do {                                                                    \
 214         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 215         unsigned long __gu_val;                                         \
 216         __chk_user_ptr(ptr);                                            \
 217         switch (sizeof(*(ptr))) {                                       \
 218         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
 219         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
 220         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
 221         default: (__gu_val) = __get_user_bad();                         \
 222         }                                                               \
 223         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 224 } while (0)
 225
 226 #define __get_user_asm_byte(x,addr,err)                         \
 227         __asm__ __volatile__(                                   \
 228         "1:     ldrbt   %1,[%2],#0\n"                           \
 229         "2:\n"                                                  \
 230         "       .section .fixup,\"ax\"\n"                       \
 231         "       .align  2\n"                                    \
 232         "3:     mov     %0, %3\n"                               \
 233         "       mov     %1, #0\n"                               \
 234         "       b       2b\n"                                   \
 235         "       .previous\n"                                    \
 236         "       .section __ex_table,\"a\"\n"                    \
 237         "       .align  3\n"                                    \
 238         "       .long   1b, 3b\n"                               \
 239         "       .previous"                                      \
 240         : "+r" (err), "=&r" (x)                                 \
 241         : "r" (addr), "i" (-EFAULT)                             \
 242         : "cc")
 243
 244 #ifndef __ARMEB__
 245 #define __get_user_asm_half(x,__gu_addr,err)                    \
 246 ({                                                              \
 247         unsigned long __b1, __b2;                               \
 248         __get_user_asm_byte(__b1, __gu_addr, err);              \
 249         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 250         (x) = __b1 | (__b2 << 8);                               \
 251 })
 252 #else
 253 #define __get_user_asm_half(x,__gu_addr,err)                    \
 254 ({                                                              \
 255         unsigned long __b1, __b2;                               \
 256         __get_user_asm_byte(__b1, __gu_addr, err);              \
 257         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 258         (x) = (__b1 << 8) | __b2;                               \
 259 })
 260 #endif
 261
 262 #define __get_user_asm_word(x,addr,err)                         \
 263         __asm__ __volatile__(                                   \
 264         "1:     ldrt    %1,[%2],#0\n"                           \
 265         "2:\n"                                                  \
 266         "       .section .fixup,\"ax\"\n"                       \
 267         "       .align  2\n"                                    \
 268         "3:     mov     %0, %3\n"                               \
 269         "       mov     %1, #0\n"                               \
 270         "       b       2b\n"                                   \
 271         "       .previous\n"                                    \
 272         "       .section __ex_table,\"a\"\n"                    \
 273         "       .align  3\n"                                    \
 274         "       .long   1b, 3b\n"                               \
 275         "       .previous"                                      \
 276         : "+r" (err), "=&r" (x)                                 \
 277         : "r" (addr), "i" (-EFAULT)                             \
 278         : "cc")
 279
 280 #define __put_user(x,ptr)                                               \
 281 ({                                                                      \
 282         long __pu_err = 0;                                              \
 283         __put_user_err((x),(ptr),__pu_err);                             \
 284         __pu_err;                                                       \
 285 })
 286
 287 #define __put_user_error(x,ptr,err)                                     \
 288 ({                                                                      \
 289         __put_user_err((x),(ptr),err);                                  \
 290         (void) 0;                                                       \
 291 })
 292
 293 #define __put_user_err(x,ptr,err)                                       \
 294 do {                                                                    \
 295         unsigned long __pu_addr = (unsigned long)(ptr);                 \
 296         __typeof__(*(ptr)) __pu_val = (x);                              \
 297         __chk_user_ptr(ptr);                                            \
 298         switch (sizeof(*(ptr))) {                                       \
 299         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
 300         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
 301         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
 302         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
 303         default: __put_user_bad();                                      \
 304         }                                                               \
 305 } while (0)
 306
 307 #define __put_user_asm_byte(x,__pu_addr,err)                    \
 308         __asm__ __volatile__(                                   \
 309         "1:     strbt   %1,[%2],#0\n"                           \
 310         "2:\n"                                                  \
 311         "       .section .fixup,\"ax\"\n"                       \
 312         "       .align  2\n"                                    \
 313         "3:     mov     %0, %3\n"                               \
 314         "       b       2b\n"                                   \
 315         "       .previous\n"                                    \
 316         "       .section __ex_table,\"a\"\n"                    \
 317         "       .align  3\n"                                    \
 318         "       .long   1b, 3b\n"                               \
 319         "       .previous"                                      \
 320         : "+r" (err)                                            \
 321         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 322         : "cc")
 323
 324 #ifndef __ARMEB__
 325 #define __put_user_asm_half(x,__pu_addr,err)                    \
 326 ({                                                              \
 327         unsigned long __temp = (unsigned long)(x);              \
 328         __put_user_asm_byte(__temp, __pu_addr, err);            \
 329         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 330 })
 331 #else
 332 #define __put_user_asm_half(x,__pu_addr,err)                    \
 333 ({                                                              \
 334         unsigned long __temp = (unsigned long)(x);              \
 335         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 336         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 337 })
 338 #endif
 339
 340 #define __put_user_asm_word(x,__pu_addr,err)                    \
 341         __asm__ __volatile__(                                   \
 342         "1:     strt    %1,[%2],#0\n"                           \
 343         "2:\n"                                                  \
 344         "       .section .fixup,\"ax\"\n"                       \
 345         "       .align  2\n"                                    \
 346         "3:     mov     %0, %3\n"                               \
 347         "       b       2b\n"                                   \
 348         "       .previous\n"                                    \
 349         "       .section __ex_table,\"a\"\n"                    \
 350         "       .align  3\n"                                    \
 351         "       .long   1b, 3b\n"                               \
 352         "       .previous"                                      \
 353         : "+r" (err)                                            \
 354         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 355         : "cc")
 356
 357 #ifndef __ARMEB__
 358 #define __reg_oper0     "%R2"
 359 #define __reg_oper1     "%Q2"
 360 #else
 361 #define __reg_oper0     "%Q2"
 362 #define __reg_oper1     "%R2"
 363 #endif
 364
 365 #define __put_user_asm_dword(x,__pu_addr,err)                   \
 366         __asm__ __volatile__(                                   \
 367         "1:     strt    " __reg_oper1 ", [%1], #4\n"            \
 368         "2:     strt    " __reg_oper0 ", [%1], #0\n"            \
 369         "3:\n"                                                  \
 370         "       .section .fixup,\"ax\"\n"                       \
 371         "       .align  2\n"                                    \
 372         "4:     mov     %0, %3\n"                               \
 373         "       b       3b\n"                                   \
 374         "       .previous\n"                                    \
 375         "       .section __ex_table,\"a\"\n"                    \
 376         "       .align  3\n"                                    \
 377         "       .long   1b, 4b\n"                               \
 378         "       .long   2b, 4b\n"                               \
 379         "       .previous"                                      \
 380         : "+r" (err), "+r" (__pu_addr)                          \
 381         : "r" (x), "i" (-EFAULT)                                \
 382         : "cc")
 383
 384
 385 #ifdef CONFIG_MMU
 386 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 387 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 388 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 389 #else
 390 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
 391 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
 392 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
 393 #endif
 394
 395 extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
 396 extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
 397
 398 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 399 {
 400         if (access_ok(VERIFY_READ, from, n))
 401                 n = __copy_from_user(to, from, n);
 402         else /* security hole - plug it */
 403                 memzero(to, n);
 404         return n;
 405 }
 406
 407 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 408 {
 409         if (access_ok(VERIFY_WRITE, to, n))
 410                 n = __copy_to_user(to, from, n);
 411         return n;
 412 }
 413
 414 #define __copy_to_user_inatomic __copy_to_user
 415 #define __copy_from_user_inatomic __copy_from_user
 416
 417 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 418 {
 419         if (access_ok(VERIFY_WRITE, to, n))
 420                 n = __clear_user(to, n);
 421         return n;
 422 }
 423
 424 static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
 425 {
 426         long res = -EFAULT;
 427         if (access_ok(VERIFY_READ, src, 1))
 428                 res = __strncpy_from_user(dst, src, count);
 429         return res;
 430 }
 431
 432 #define strlen_user(s)  strnlen_user(s, ~0UL >> 1)
 433
 434 static inline long __must_check strnlen_user(const char __user *s, long n)
 435 {
 436         unsigned long res = 0;
 437
 438         if (__addr_ok(s))
 439                 res = __strnlen_user(s, n);
 440
 441         return res;
 442 }
 443
 444 #endif /* _ASMARM_UACCESS_H */