arch/powerpc/include/asm/uaccess.h

   1 #ifndef _ARCH_POWERPC_UACCESS_H
   2 #define _ARCH_POWERPC_UACCESS_H
   3
   4 #ifdef __KERNEL__
   5 #ifndef __ASSEMBLY__
   6
   7 #include <linux/sched.h>
   8 #include <linux/errno.h>
   9 #include <asm/asm-compat.h>
  10 #include <asm/processor.h>
  11 #include <asm/page.h>
  12 #include <asm/kup.h>
  13
  14 #define VERIFY_READ     0
  15 #define VERIFY_WRITE    1
  16
  17 /*
  18  * The fs value determines whether argument validity checking should be
  19  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  20  * get_fs() == KERNEL_DS, checking is bypassed.
  21  *
  22  * For historical reasons, these macros are grossly misnamed.
  23  *
  24  * The fs/ds values are now the highest legal address in the "segment".
  25  * This simplifies the checking in the routines below.
  26  */
  27
  28 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  29
  30 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
  31 #ifdef __powerpc64__
  32 /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
  33 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
  34 #else
  35 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
  36 #endif
  37
  38 #define get_ds()        (KERNEL_DS)
  39 #define get_fs()        (current->thread.fs)
  40 #define set_fs(val)     (current->thread.fs = (val))
  41
  42 #define segment_eq(a, b)        ((a).seg == (b).seg)
  43
  44 #define user_addr_max() (get_fs().seg)
  45
  46 #ifdef __powerpc64__
  47 /*
  48  * This check is sufficient because there is a large enough
  49  * gap between user addresses and the kernel addresses
  50  */
  51 #define __access_ok(addr, size, segment)        \
  52         (((addr) <= (segment).seg) && ((size) <= (segment).seg))
  53
  54 #else
  55
  56 #define __access_ok(addr, size, segment)        \
  57         (((addr) <= (segment).seg) &&           \
  58          (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))
  59
  60 #endif
  61
  62 #define access_ok(type, addr, size)             \
  63         (__chk_user_ptr(addr), (void)(type),            \
  64          __access_ok((__force unsigned long)(addr), (size), get_fs()))
  65
  66 /*
  67  * The exception table consists of pairs of addresses: the first is the
  68  * address of an instruction that is allowed to fault, and the second is
  69  * the address at which the program should continue.  No registers are
  70  * modified, so it is entirely up to the continuation code to figure out
  71  * what to do.
  72  *
  73  * All the routines below use bits of fixup code that are out of line
  74  * with the main instruction path.  This means when everything is well,
  75  * we don't even have to jump over them.  Further, they do not intrude
  76  * on our cache or tlb entries.
  77  */
  78
  79 struct exception_table_entry {
  80         unsigned long insn;
  81         unsigned long fixup;
  82 };
  83
  84 /*
  85  * These are the main single-value transfer routines.  They automatically
  86  * use the right size if we just have the right pointer type.
  87  *
  88  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  89  * and yet we don't want to do any pointers, because that is too much
  90  * of a performance impact. Thus we have a few rather ugly macros here,
  91  * and hide all the ugliness from the user.
  92  *
  93  * The "__xxx" versions of the user access functions are versions that
  94  * do not verify the address space, that must have been done previously
  95  * with a separate "access_ok()" call (this is used when we do multiple
  96  * accesses to the same area of user memory).
  97  *
  98  * As we use the same address space for kernel and user data on the
  99  * PowerPC, we can just do these as direct assignments.  (Of course, the
 100  * exception handling means that it's no longer "just"...)
 101  *
 102  */
 103 #define get_user(x, ptr) \
 104         __get_user_check((x), (ptr), sizeof(*(ptr)))
 105 #define put_user(x, ptr) \
 106         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 107
 108 #define __get_user(x, ptr) \
 109         __get_user_nocheck((x), (ptr), sizeof(*(ptr)), true)
 110 #define __put_user(x, ptr) \
 111         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), true)
 112
 113 #define __get_user_allowed(x, ptr) \
 114         __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false)
 115 #define __put_user_allowed(x, ptr) \
 116         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), false)
 117
 118 #define __get_user_inatomic(x, ptr) \
 119         __get_user_nosleep((x), (ptr), sizeof(*(ptr)))
 120 #define __put_user_inatomic(x, ptr) \
 121         __put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 122
 123 #define __get_user_unaligned __get_user
 124 #define __put_user_unaligned __put_user
 125
 126 extern long __put_user_bad(void);
 127
 128 /*
 129  * We don't tell gcc that we are accessing memory, but this is OK
 130  * because we do not write to any memory gcc knows about, so there
 131  * are no aliasing issues.
 132  */
 133 #define __put_user_asm(x, addr, err, op)                        \
 134         __asm__ __volatile__(                                   \
 135                 "1:     " op " %1,0(%2) # put_user\n"           \
 136                 "2:\n"                                          \
 137                 ".section .fixup,\"ax\"\n"                      \
 138                 "3:     li %0,%3\n"                             \
 139                 "       b 2b\n"                                 \
 140                 ".previous\n"                                   \
 141                 ".section __ex_table,\"a\"\n"                   \
 142                         PPC_LONG_ALIGN "\n"                     \
 143                         PPC_LONG "1b,3b\n"                      \
 144                 ".previous"                                     \
 145                 : "=r" (err)                                    \
 146                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 147
 148 #ifdef __powerpc64__
 149 #define __put_user_asm2(x, ptr, retval)                         \
 150           __put_user_asm(x, ptr, retval, "std")
 151 #else /* __powerpc64__ */
 152 #define __put_user_asm2(x, addr, err)                           \
 153         __asm__ __volatile__(                                   \
 154                 "1:     stw %1,0(%2)\n"                         \
 155                 "2:     stw %1+1,4(%2)\n"                       \
 156                 "3:\n"                                          \
 157                 ".section .fixup,\"ax\"\n"                      \
 158                 "4:     li %0,%3\n"                             \
 159                 "       b 3b\n"                                 \
 160                 ".previous\n"                                   \
 161                 ".section __ex_table,\"a\"\n"                   \
 162                         PPC_LONG_ALIGN "\n"                     \
 163                         PPC_LONG "1b,4b\n"                      \
 164                         PPC_LONG "2b,4b\n"                      \
 165                 ".previous"                                     \
 166                 : "=r" (err)                                    \
 167                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 168 #endif /* __powerpc64__ */
 169
 170 #define __put_user_size_allowed(x, ptr, size, retval)           \
 171 do {                                                            \
 172         retval = 0;                                             \
 173         switch (size) {                                         \
 174           case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
 175           case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
 176           case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
 177           case 8: __put_user_asm2(x, ptr, retval); break;       \
 178           default: __put_user_bad();                            \
 179         }                                                       \
 180 } while (0)
 181
 182 #define __put_user_size(x, ptr, size, retval)                   \
 183 do {                                                            \
 184         allow_write_to_user(ptr, size);                         \
 185         __put_user_size_allowed(x, ptr, size, retval);          \
 186         prevent_write_to_user(ptr, size);                       \
 187 } while (0)
 188
 189 #define __put_user_nocheck(x, ptr, size, do_allow)                      \
 190 ({                                                              \
 191         long __pu_err;                                          \
 192         __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
 193         __typeof__(*(ptr)) __pu_val = (x);                      \
 194         __typeof__(size) __pu_size = (size);                    \
 195                                                                 \
 196         if (!is_kernel_addr((unsigned long)__pu_addr))          \
 197                 might_fault();                                  \
 198         __chk_user_ptr(__pu_addr);                              \
 199         if (do_allow)                                                           \
 200                 __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err);      \
 201         else                                                                    \
 202                 __put_user_size_allowed(__pu_val, __pu_addr, __pu_size, __pu_err); \
 203                                                                 \
 204         __pu_err;                                               \
 205 })
 206
 207 #define __put_user_check(x, ptr, size)                                  \
 208 ({                                                                      \
 209         long __pu_err = -EFAULT;                                        \
 210         __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
 211         __typeof__(*(ptr)) __pu_val = (x);                              \
 212         __typeof__(size) __pu_size = (size);                            \
 213                                                                         \
 214         might_fault();                                                  \
 215         if (access_ok(VERIFY_WRITE, __pu_addr, __pu_size))                      \
 216                 __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \
 217                                                                         \
 218         __pu_err;                                                       \
 219 })
 220
 221 #define __put_user_nosleep(x, ptr, size)                        \
 222 ({                                                              \
 223         long __pu_err;                                          \
 224         __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
 225         __typeof__(*(ptr)) __pu_val = (x);                      \
 226         __typeof__(size) __pu_size = (size);                    \
 227                                                                 \
 228         __chk_user_ptr(__pu_addr);                              \
 229         __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \
 230                                                                 \
 231         __pu_err;                                               \
 232 })
 233
 234
 235 extern long __get_user_bad(void);
 236
 237 #define __get_user_asm(x, addr, err, op)                \
 238         __asm__ __volatile__(                           \
 239                 "1:     "op" %1,0(%2)   # get_user\n"   \
 240                 "2:\n"                                  \
 241                 ".section .fixup,\"ax\"\n"              \
 242                 "3:     li %0,%3\n"                     \
 243                 "       li %1,0\n"                      \
 244                 "       b 2b\n"                         \
 245                 ".previous\n"                           \
 246                 ".section __ex_table,\"a\"\n"           \
 247                         PPC_LONG_ALIGN "\n"             \
 248                         PPC_LONG "1b,3b\n"              \
 249                 ".previous"                             \
 250                 : "=r" (err), "=r" (x)                  \
 251                 : "b" (addr), "i" (-EFAULT), "0" (err))
 252
 253 #ifdef __powerpc64__
 254 #define __get_user_asm2(x, addr, err)                   \
 255         __get_user_asm(x, addr, err, "ld")
 256 #else /* __powerpc64__ */
 257 #define __get_user_asm2(x, addr, err)                   \
 258         __asm__ __volatile__(                           \
 259                 "1:     lwz %1,0(%2)\n"                 \
 260                 "2:     lwz %1+1,4(%2)\n"               \
 261                 "3:\n"                                  \
 262                 ".section .fixup,\"ax\"\n"              \
 263                 "4:     li %0,%3\n"                     \
 264                 "       li %1,0\n"                      \
 265                 "       li %1+1,0\n"                    \
 266                 "       b 3b\n"                         \
 267                 ".previous\n"                           \
 268                 ".section __ex_table,\"a\"\n"           \
 269                         PPC_LONG_ALIGN "\n"             \
 270                         PPC_LONG "1b,4b\n"              \
 271                         PPC_LONG "2b,4b\n"              \
 272                 ".previous"                             \
 273                 : "=r" (err), "=&r" (x)                 \
 274                 : "b" (addr), "i" (-EFAULT), "0" (err))
 275 #endif /* __powerpc64__ */
 276
 277 #define __get_user_size_allowed(x, ptr, size, retval)           \
 278 do {                                                            \
 279         retval = 0;                                             \
 280         __chk_user_ptr(ptr);                                    \
 281         if (size > sizeof(x))                                   \
 282                 (x) = __get_user_bad();                         \
 283         switch (size) {                                         \
 284         case 1: __get_user_asm(x, ptr, retval, "lbz"); break;   \
 285         case 2: __get_user_asm(x, ptr, retval, "lhz"); break;   \
 286         case 4: __get_user_asm(x, ptr, retval, "lwz"); break;   \
 287         case 8: __get_user_asm2(x, ptr, retval);  break;        \
 288         default: (x) = __get_user_bad();                        \
 289         }                                                       \
 290 } while (0)
 291
 292 #define __get_user_size(x, ptr, size, retval)                   \
 293 do {                                                            \
 294         allow_read_from_user(ptr, size);                        \
 295         __get_user_size_allowed(x, ptr, size, retval);          \
 296         prevent_read_from_user(ptr, size);                      \
 297 } while (0)
 298
 299 #define __get_user_nocheck(x, ptr, size, do_allow)                      \
 300 ({                                                              \
 301         long __gu_err;                                          \
 302         unsigned long __gu_val;                                 \
 303         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 304         __typeof__(size) __gu_size = (size);                    \
 305                                                                 \
 306         __chk_user_ptr(__gu_addr);                              \
 307         if (!is_kernel_addr((unsigned long)__gu_addr))          \
 308                 might_fault();                                  \
 309         barrier_nospec();                                       \
 310         if (do_allow)                                                           \
 311                 __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err);      \
 312         else                                                                    \
 313                 __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \
 314         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 315                                                                 \
 316         __gu_err;                                               \
 317 })
 318
 319 #ifndef __powerpc64__
 320 #define __get_user64_nocheck(x, ptr, size)                      \
 321 ({                                                              \
 322         long __gu_err;                                          \
 323         long long __gu_val;                                     \
 324         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 325         __chk_user_ptr(ptr);                                    \
 326         if (!is_kernel_addr((unsigned long)__gu_addr))          \
 327                 might_fault();                                  \
 328         barrier_nospec();                                       \
 329         __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 330         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 331         __gu_err;                                               \
 332 })
 333 #endif /* __powerpc64__ */
 334
 335 #define __get_user_check(x, ptr, size)                                  \
 336 ({                                                                      \
 337         long __gu_err = -EFAULT;                                        \
 338         unsigned long  __gu_val = 0;                                    \
 339         __typeof__(*(ptr)) __user *__gu_addr = (ptr);           \
 340         __typeof__(size) __gu_size = (size);                            \
 341                                                                         \
 342         might_fault();                                                  \
 343         if (access_ok(VERIFY_READ, __gu_addr, __gu_size)) {             \
 344                 barrier_nospec();                                       \
 345                 __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
 346         }                                                               \
 347         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 348                                                                         \
 349         __gu_err;                                                       \
 350 })
 351
 352 #define __get_user_nosleep(x, ptr, size)                        \
 353 ({                                                              \
 354         long __gu_err;                                          \
 355         unsigned long __gu_val;                                 \
 356         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 357         __typeof__(size) __gu_size = (size);                    \
 358                                                                 \
 359         __chk_user_ptr(__gu_addr);                              \
 360         barrier_nospec();                                       \
 361         __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
 362         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 363                                                                 \
 364         __gu_err;                                               \
 365 })
 366
 367
 368 /* more complex routines */
 369
 370 extern unsigned long __copy_tofrom_user(void __user *to,
 371                 const void __user *from, unsigned long size);
 372
 373 #ifndef __powerpc64__
 374
 375 static inline unsigned long copy_from_user(void *to,
 376                 const void __user *from, unsigned long n)
 377 {
 378         unsigned long ret;
 379
 380         if (likely(access_ok(VERIFY_READ, from, n))) {
 381                 allow_user_access(to, from, n);
 382                 barrier_nospec();
 383                 ret = __copy_tofrom_user((__force void __user *)to, from, n);
 384                 prevent_user_access(to, from, n);
 385                 return ret;
 386         }
 387         memset(to, 0, n);
 388         return n;
 389 }
 390
 391 static inline unsigned long copy_to_user(void __user *to,
 392                 const void *from, unsigned long n)
 393 {
 394         if (access_ok(VERIFY_WRITE, to, n))
 395                 return __copy_tofrom_user(to, (__force void __user *)from, n);
 396         return n;
 397 }
 398
 399 #else /* __powerpc64__ */
 400
 401 #define __copy_in_user(to, from, size) \
 402         __copy_tofrom_user((to), (from), (size))
 403
 404 extern unsigned long copy_from_user(void *to, const void __user *from,
 405                                     unsigned long n);
 406 extern unsigned long copy_to_user(void __user *to, const void *from,
 407                                   unsigned long n);
 408 extern unsigned long copy_in_user(void __user *to, const void __user *from,
 409                                   unsigned long n);
 410
 411 #endif /* __powerpc64__ */
 412
 413 static inline unsigned long __copy_from_user_inatomic(void *to,
 414                 const void __user *from, unsigned long n)
 415 {
 416         unsigned long ret;
 417         if (__builtin_constant_p(n) && (n <= 8)) {
 418                 ret = 1;
 419
 420                 switch (n) {
 421                 case 1:
 422                         barrier_nospec();
 423                         __get_user_size(*(u8 *)to, from, 1, ret);
 424                         break;
 425                 case 2:
 426                         barrier_nospec();
 427                         __get_user_size(*(u16 *)to, from, 2, ret);
 428                         break;
 429                 case 4:
 430                         barrier_nospec();
 431                         __get_user_size(*(u32 *)to, from, 4, ret);
 432                         break;
 433                 case 8:
 434                         barrier_nospec();
 435                         __get_user_size(*(u64 *)to, from, 8, ret);
 436                         break;
 437                 }
 438                 if (ret == 0)
 439                         return 0;
 440         }
 441
 442         barrier_nospec();
 443         allow_read_from_user(from, n);
 444         ret = __copy_tofrom_user((__force void __user *)to, from, n);
 445         prevent_read_from_user(from, n);
 446         return ret;
 447 }
 448
 449 static inline unsigned long __copy_to_user_inatomic(void __user *to,
 450                 const void *from, unsigned long n)
 451 {
 452         unsigned long ret;
 453
 454         if (__builtin_constant_p(n) && (n <= 8)) {
 455                 ret = 1;
 456
 457                 switch (n) {
 458                 case 1:
 459                         __put_user_size_allowed(*(u8 *)from, (u8 __user *)to, 1, ret);
 460                         break;
 461                 case 2:
 462                         __put_user_size_allowed(*(u16 *)from, (u16 __user *)to, 2, ret);
 463                         break;
 464                 case 4:
 465                         __put_user_size_allowed(*(u32 *)from, (u32 __user *)to, 4, ret);
 466                         break;
 467                 case 8:
 468                         __put_user_size_allowed(*(u64 *)from, (u64 __user *)to, 8, ret);
 469                         break;
 470                 }
 471                 if (ret == 0)
 472                         return 0;
 473         }
 474
 475         allow_write_to_user(to, n);
 476         ret = __copy_tofrom_user(to, (__force const void __user *)from, n);
 477         prevent_write_to_user(to, n);
 478         return ret;
 479 }
 480
 481 static inline unsigned long __copy_from_user(void *to,
 482                 const void __user *from, unsigned long size)
 483 {
 484         might_fault();
 485         return __copy_from_user_inatomic(to, from, size);
 486 }
 487
 488 static inline unsigned long __copy_to_user(void __user *to,
 489                 const void *from, unsigned long size)
 490 {
 491         might_fault();
 492         return __copy_to_user_inatomic(to, from, size);
 493 }
 494
 495 unsigned long __arch_clear_user(void __user *addr, unsigned long size);
 496
 497 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 498 {
 499         unsigned long ret = size;
 500         might_fault();
 501         if (likely(access_ok(VERIFY_WRITE, addr, size))) {
 502                 allow_write_to_user(addr, size);
 503                 ret = __arch_clear_user(addr, size);
 504                 prevent_write_to_user(addr, size);
 505         }
 506         return ret;
 507 }
 508
 509 static inline unsigned long __clear_user(void __user *addr, unsigned long size)
 510 {
 511         return clear_user(addr, size);
 512 }
 513
 514 extern long strncpy_from_user(char *dst, const char __user *src, long count);
 515 extern __must_check long strlen_user(const char __user *str);
 516 extern __must_check long strnlen_user(const char __user *str, long n);
 517
 518
 519 #define user_access_begin()     do { } while (0)
 520 #define user_access_end()       prevent_user_access(NULL, NULL, ~0ul)
 521
 522 #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
 523 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
 524 #define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e)
 525 #define unsafe_copy_to_user(d, s, l, e) \
 526         unsafe_op_wrap(__copy_to_user_inatomic(d, s, l), e)
 527
 528 #endif  /* __ASSEMBLY__ */
 529 #endif /* __KERNEL__ */
 530
 531 #endif  /* _ARCH_POWERPC_UACCESS_H */