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 #define __get_user_check(x, ptr, size)                                  \
 320 ({                                                                      \
 321         long __gu_err = -EFAULT;                                        \
 322         unsigned long  __gu_val = 0;                                    \
 323         __typeof__(*(ptr)) __user *__gu_addr = (ptr);           \
 324         __typeof__(size) __gu_size = (size);                            \
 325                                                                         \
 326         might_fault();                                                  \
 327         if (access_ok(VERIFY_READ, __gu_addr, __gu_size)) {             \
 328                 barrier_nospec();                                       \
 329                 __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
 330         }                                                               \
 331         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 332                                                                         \
 333         __gu_err;                                                       \
 334 })
 335
 336 #define __get_user_nosleep(x, ptr, size)                        \
 337 ({                                                              \
 338         long __gu_err;                                          \
 339         unsigned long __gu_val;                                 \
 340         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 341         __typeof__(size) __gu_size = (size);                    \
 342                                                                 \
 343         __chk_user_ptr(__gu_addr);                              \
 344         barrier_nospec();                                       \
 345         __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
 346         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 347                                                                 \
 348         __gu_err;                                               \
 349 })
 350
 351
 352 /* more complex routines */
 353
 354 extern unsigned long __copy_tofrom_user(void __user *to,
 355                 const void __user *from, unsigned long size);
 356
 357 #ifndef __powerpc64__
 358
 359 static inline unsigned long copy_from_user(void *to,
 360                 const void __user *from, unsigned long n)
 361 {
 362         unsigned long ret;
 363
 364         if (likely(access_ok(VERIFY_READ, from, n))) {
 365                 check_object_size(to, n, false);
 366                 allow_user_access(to, from, n);
 367                 ret = __copy_tofrom_user((__force void __user *)to, from, n);
 368                 prevent_user_access(to, from, n);
 369                 return ret;
 370         }
 371         memset(to, 0, n);
 372         return n;
 373 }
 374
 375 static inline unsigned long copy_to_user(void __user *to,
 376                 const void *from, unsigned long n)
 377 {
 378         if (access_ok(VERIFY_WRITE, to, n)) {
 379                 check_object_size(from, n, true);
 380                 return __copy_tofrom_user(to, (__force void __user *)from, n);
 381         }
 382         return n;
 383 }
 384
 385 #else /* __powerpc64__ */
 386
 387 #define __copy_in_user(to, from, size) \
 388         __copy_tofrom_user((to), (from), (size))
 389
 390 extern unsigned long copy_from_user(void *to, const void __user *from,
 391                                     unsigned long n);
 392 extern unsigned long copy_to_user(void __user *to, const void *from,
 393                                   unsigned long n);
 394 extern unsigned long copy_in_user(void __user *to, const void __user *from,
 395                                   unsigned long n);
 396
 397 #endif /* __powerpc64__ */
 398
 399 static inline unsigned long __copy_from_user_inatomic(void *to,
 400                 const void __user *from, unsigned long n)
 401 {
 402         unsigned long ret;
 403         if (__builtin_constant_p(n) && (n <= 8)) {
 404                 ret = 1;
 405
 406                 switch (n) {
 407                 case 1:
 408                         barrier_nospec();
 409                         __get_user_size(*(u8 *)to, from, 1, ret);
 410                         break;
 411                 case 2:
 412                         barrier_nospec();
 413                         __get_user_size(*(u16 *)to, from, 2, ret);
 414                         break;
 415                 case 4:
 416                         barrier_nospec();
 417                         __get_user_size(*(u32 *)to, from, 4, ret);
 418                         break;
 419                 case 8:
 420                         barrier_nospec();
 421                         __get_user_size(*(u64 *)to, from, 8, ret);
 422                         break;
 423                 }
 424                 if (ret == 0)
 425                         return 0;
 426         }
 427
 428         check_object_size(to, n, false);
 429
 430         barrier_nospec();
 431         allow_read_from_user(from, n);
 432         ret = __copy_tofrom_user((__force void __user *)to, from, n);
 433         prevent_read_from_user(from, n);
 434         return ret;
 435 }
 436
 437 static inline unsigned long __copy_to_user_inatomic(void __user *to,
 438                 const void *from, unsigned long n)
 439 {
 440         unsigned long ret;
 441
 442         if (__builtin_constant_p(n) && (n <= 8)) {
 443                 ret = 1;
 444
 445                 switch (n) {
 446                 case 1:
 447                         __put_user_size_allowed(*(u8 *)from, (u8 __user *)to, 1, ret);
 448                         break;
 449                 case 2:
 450                         __put_user_size_allowed(*(u16 *)from, (u16 __user *)to, 2, ret);
 451                         break;
 452                 case 4:
 453                         __put_user_size_allowed(*(u32 *)from, (u32 __user *)to, 4, ret);
 454                         break;
 455                 case 8:
 456                         __put_user_size_allowed(*(u64 *)from, (u64 __user *)to, 8, ret);
 457                         break;
 458                 }
 459                 if (ret == 0)
 460                         return 0;
 461         }
 462
 463         check_object_size(from, n, true);
 464         allow_write_to_user(to, n);
 465         ret = __copy_tofrom_user(to, (__force const void __user *)from, n);
 466         prevent_write_to_user(to, n);
 467         return ret;
 468 }
 469
 470 static inline unsigned long __copy_from_user(void *to,
 471                 const void __user *from, unsigned long size)
 472 {
 473         might_fault();
 474         return __copy_from_user_inatomic(to, from, size);
 475 }
 476
 477 static inline unsigned long __copy_to_user(void __user *to,
 478                 const void *from, unsigned long size)
 479 {
 480         might_fault();
 481         return __copy_to_user_inatomic(to, from, size);
 482 }
 483
 484 unsigned long __arch_clear_user(void __user *addr, unsigned long size);
 485
 486 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 487 {
 488         unsigned long ret = size;
 489         might_fault();
 490         if (likely(access_ok(VERIFY_WRITE, addr, size))) {
 491                 allow_write_to_user(addr, size);
 492                 ret = __arch_clear_user(addr, size);
 493                 prevent_write_to_user(addr, size);
 494         }
 495         return ret;
 496 }
 497
 498 static inline unsigned long __clear_user(void __user *addr, unsigned long size)
 499 {
 500         return clear_user(addr, size);
 501 }
 502
 503 extern long strncpy_from_user(char *dst, const char __user *src, long count);
 504 extern __must_check long strlen_user(const char __user *str);
 505 extern __must_check long strnlen_user(const char __user *str, long n);
 506
 507
 508 #define user_access_begin()     do { } while (0)
 509 #define user_access_end()       prevent_user_access(NULL, NULL, ~0ul)
 510
 511 #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
 512 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
 513 #define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e)
 514 #define unsafe_copy_to_user(d, s, l, e) \
 515         unsafe_op_wrap(__copy_to_user_inatomic(d, s, l), e)
 516
 517 #endif  /* __ASSEMBLY__ */
 518 #endif /* __KERNEL__ */
 519
 520 #endif  /* _ARCH_POWERPC_UACCESS_H */