arch/powerpc/include/asm/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ARCH_POWERPC_UACCESS_H
   3 #define _ARCH_POWERPC_UACCESS_H
   4
   5 #include <asm/asm-compat.h>
   6 #include <asm/ppc_asm.h>
   7 #include <asm/processor.h>
   8 #include <asm/page.h>
   9 #include <asm/extable.h>
  10 #include <asm/kup.h>
  11
  12 /*
  13  * The fs value determines whether argument validity checking should be
  14  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  15  * get_fs() == KERNEL_DS, checking is bypassed.
  16  *
  17  * For historical reasons, these macros are grossly misnamed.
  18  *
  19  * The fs/ds values are now the highest legal address in the "segment".
  20  * This simplifies the checking in the routines below.
  21  */
  22
  23 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  24
  25 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
  26 #ifdef __powerpc64__
  27 /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
  28 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
  29 #else
  30 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
  31 #endif
  32
  33 #define get_ds()        (KERNEL_DS)
  34 #define get_fs()        (current->thread.fs)
  35 #define set_fs(val)     (current->thread.fs = (val))
  36
  37 #define segment_eq(a, b)        ((a).seg == (b).seg)
  38
  39 #define user_addr_max() (get_fs().seg)
  40
  41 #ifdef __powerpc64__
  42 /*
  43  * This check is sufficient because there is a large enough
  44  * gap between user addresses and the kernel addresses
  45  */
  46 #define __access_ok(addr, size, segment)        \
  47         (((addr) <= (segment).seg) && ((size) <= (segment).seg))
  48
  49 #else
  50
  51 #define __access_ok(addr, size, segment)        \
  52         (((addr) <= (segment).seg) &&           \
  53          (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))
  54
  55 #endif
  56
  57 #define access_ok(type, addr, size)             \
  58         (__chk_user_ptr(addr), (void)(type),            \
  59          __access_ok((__force unsigned long)(addr), (size), get_fs()))
  60
  61 /*
  62  * These are the main single-value transfer routines.  They automatically
  63  * use the right size if we just have the right pointer type.
  64  *
  65  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  66  * and yet we don't want to do any pointers, because that is too much
  67  * of a performance impact. Thus we have a few rather ugly macros here,
  68  * and hide all the ugliness from the user.
  69  *
  70  * The "__xxx" versions of the user access functions are versions that
  71  * do not verify the address space, that must have been done previously
  72  * with a separate "access_ok()" call (this is used when we do multiple
  73  * accesses to the same area of user memory).
  74  *
  75  * As we use the same address space for kernel and user data on the
  76  * PowerPC, we can just do these as direct assignments.  (Of course, the
  77  * exception handling means that it's no longer "just"...)
  78  *
  79  */
  80 #define get_user(x, ptr) \
  81         __get_user_check((x), (ptr), sizeof(*(ptr)))
  82 #define put_user(x, ptr) \
  83         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  84
  85 #define __get_user(x, ptr) \
  86         __get_user_nocheck((x), (ptr), sizeof(*(ptr)), true)
  87 #define __put_user(x, ptr) \
  88         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), true)
  89
  90 #define __get_user_allowed(x, ptr) \
  91         __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false)
  92 #define __put_user_allowed(x, ptr) \
  93         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), false)
  94
  95 #define __get_user_inatomic(x, ptr) \
  96         __get_user_nosleep((x), (ptr), sizeof(*(ptr)))
  97 #define __put_user_inatomic(x, ptr) \
  98         __put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  99
 100 extern long __put_user_bad(void);
 101
 102 /*
 103  * We don't tell gcc that we are accessing memory, but this is OK
 104  * because we do not write to any memory gcc knows about, so there
 105  * are no aliasing issues.
 106  */
 107 #define __put_user_asm(x, addr, err, op)                        \
 108         __asm__ __volatile__(                                   \
 109                 "1:     " op " %1,0(%2) # put_user\n"           \
 110                 "2:\n"                                          \
 111                 ".section .fixup,\"ax\"\n"                      \
 112                 "3:     li %0,%3\n"                             \
 113                 "       b 2b\n"                                 \
 114                 ".previous\n"                                   \
 115                 EX_TABLE(1b, 3b)                                \
 116                 : "=r" (err)                                    \
 117                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 118
 119 #ifdef __powerpc64__
 120 #define __put_user_asm2(x, ptr, retval)                         \
 121           __put_user_asm(x, ptr, retval, "std")
 122 #else /* __powerpc64__ */
 123 #define __put_user_asm2(x, addr, err)                           \
 124         __asm__ __volatile__(                                   \
 125                 "1:     stw %1,0(%2)\n"                         \
 126                 "2:     stw %1+1,4(%2)\n"                       \
 127                 "3:\n"                                          \
 128                 ".section .fixup,\"ax\"\n"                      \
 129                 "4:     li %0,%3\n"                             \
 130                 "       b 3b\n"                                 \
 131                 ".previous\n"                                   \
 132                 EX_TABLE(1b, 4b)                                \
 133                 EX_TABLE(2b, 4b)                                \
 134                 : "=r" (err)                                    \
 135                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 136 #endif /* __powerpc64__ */
 137
 138 #define __put_user_size_allowed(x, ptr, size, retval)           \
 139 do {                                                            \
 140         retval = 0;                                             \
 141         switch (size) {                                         \
 142           case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
 143           case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
 144           case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
 145           case 8: __put_user_asm2(x, ptr, retval); break;       \
 146           default: __put_user_bad();                            \
 147         }                                                       \
 148 } while (0)
 149
 150 #define __put_user_size(x, ptr, size, retval)                   \
 151 do {                                                            \
 152         allow_write_to_user(ptr, size);                         \
 153         __put_user_size_allowed(x, ptr, size, retval);          \
 154         prevent_write_to_user(ptr, size);                       \
 155 } while (0)
 156
 157 #define __put_user_nocheck(x, ptr, size, do_allow)                      \
 158 ({                                                              \
 159         long __pu_err;                                          \
 160         __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
 161         __typeof__(*(ptr)) __pu_val = (x);                      \
 162         __typeof__(size) __pu_size = (size);                    \
 163                                                                 \
 164         if (!is_kernel_addr((unsigned long)__pu_addr))          \
 165                 might_fault();                                  \
 166         __chk_user_ptr(__pu_addr);                              \
 167         if (do_allow)                                                           \
 168                 __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err);      \
 169         else                                                                    \
 170                 __put_user_size_allowed(__pu_val, __pu_addr, __pu_size, __pu_err); \
 171                                                                 \
 172         __pu_err;                                               \
 173 })
 174
 175 #define __put_user_check(x, ptr, size)                                  \
 176 ({                                                                      \
 177         long __pu_err = -EFAULT;                                        \
 178         __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
 179         __typeof__(*(ptr)) __pu_val = (x);                              \
 180         __typeof__(size) __pu_size = (size);                            \
 181                                                                         \
 182         might_fault();                                                  \
 183         if (access_ok(VERIFY_WRITE, __pu_addr, __pu_size))                      \
 184                 __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \
 185                                                                         \
 186         __pu_err;                                                       \
 187 })
 188
 189 #define __put_user_nosleep(x, ptr, size)                        \
 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         __chk_user_ptr(__pu_addr);                              \
 197         __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \
 198                                                                 \
 199         __pu_err;                                               \
 200 })
 201
 202
 203 extern long __get_user_bad(void);
 204
 205 #define __get_user_asm(x, addr, err, op)                \
 206         __asm__ __volatile__(                           \
 207                 "1:     "op" %1,0(%2)   # get_user\n"   \
 208                 "2:\n"                                  \
 209                 ".section .fixup,\"ax\"\n"              \
 210                 "3:     li %0,%3\n"                     \
 211                 "       li %1,0\n"                      \
 212                 "       b 2b\n"                         \
 213                 ".previous\n"                           \
 214                 EX_TABLE(1b, 3b)                        \
 215                 : "=r" (err), "=r" (x)                  \
 216                 : "b" (addr), "i" (-EFAULT), "0" (err))
 217
 218 #ifdef __powerpc64__
 219 #define __get_user_asm2(x, addr, err)                   \
 220         __get_user_asm(x, addr, err, "ld")
 221 #else /* __powerpc64__ */
 222 #define __get_user_asm2(x, addr, err)                   \
 223         __asm__ __volatile__(                           \
 224                 "1:     lwz %1,0(%2)\n"                 \
 225                 "2:     lwz %1+1,4(%2)\n"               \
 226                 "3:\n"                                  \
 227                 ".section .fixup,\"ax\"\n"              \
 228                 "4:     li %0,%3\n"                     \
 229                 "       li %1,0\n"                      \
 230                 "       li %1+1,0\n"                    \
 231                 "       b 3b\n"                         \
 232                 ".previous\n"                           \
 233                 EX_TABLE(1b, 4b)                        \
 234                 EX_TABLE(2b, 4b)                        \
 235                 : "=r" (err), "=&r" (x)                 \
 236                 : "b" (addr), "i" (-EFAULT), "0" (err))
 237 #endif /* __powerpc64__ */
 238
 239 #define __get_user_size_allowed(x, ptr, size, retval)           \
 240 do {                                                            \
 241         retval = 0;                                             \
 242         __chk_user_ptr(ptr);                                    \
 243         if (size > sizeof(x))                                   \
 244                 (x) = __get_user_bad();                         \
 245         switch (size) {                                         \
 246         case 1: __get_user_asm(x, ptr, retval, "lbz"); break;   \
 247         case 2: __get_user_asm(x, ptr, retval, "lhz"); break;   \
 248         case 4: __get_user_asm(x, ptr, retval, "lwz"); break;   \
 249         case 8: __get_user_asm2(x, ptr, retval);  break;        \
 250         default: (x) = __get_user_bad();                        \
 251         }                                                       \
 252 } while (0)
 253
 254 #define __get_user_size(x, ptr, size, retval)                   \
 255 do {                                                            \
 256         allow_read_from_user(ptr, size);                        \
 257         __get_user_size_allowed(x, ptr, size, retval);          \
 258         prevent_read_from_user(ptr, size);                      \
 259 } while (0)
 260
 261 /*
 262  * This is a type: either unsigned long, if the argument fits into
 263  * that type, or otherwise unsigned long long.
 264  */
 265 #define __long_type(x) \
 266         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 267
 268 #define __get_user_nocheck(x, ptr, size, do_allow)                      \
 269 ({                                                              \
 270         long __gu_err;                                          \
 271         __long_type(*(ptr)) __gu_val;                           \
 272         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 273         __typeof__(size) __gu_size = (size);                    \
 274                                                                 \
 275         __chk_user_ptr(__gu_addr);                              \
 276         if (!is_kernel_addr((unsigned long)__gu_addr))          \
 277                 might_fault();                                  \
 278         barrier_nospec();                                       \
 279         if (do_allow)                                                           \
 280                 __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err);      \
 281         else                                                                    \
 282                 __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \
 283         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 284                                                                 \
 285         __gu_err;                                               \
 286 })
 287
 288 #define __get_user_check(x, ptr, size)                                  \
 289 ({                                                                      \
 290         long __gu_err = -EFAULT;                                        \
 291         __long_type(*(ptr)) __gu_val = 0;                               \
 292         __typeof__(*(ptr)) __user *__gu_addr = (ptr);           \
 293         __typeof__(size) __gu_size = (size);                            \
 294                                                                         \
 295         might_fault();                                                  \
 296         if (access_ok(VERIFY_READ, __gu_addr, __gu_size)) {             \
 297                 barrier_nospec();                                       \
 298                 __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
 299         }                                                               \
 300         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 301                                                                         \
 302         __gu_err;                                                       \
 303 })
 304
 305 #define __get_user_nosleep(x, ptr, size)                        \
 306 ({                                                              \
 307         long __gu_err;                                          \
 308         __long_type(*(ptr)) __gu_val;                           \
 309         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 310         __typeof__(size) __gu_size = (size);                    \
 311                                                                 \
 312         __chk_user_ptr(__gu_addr);                              \
 313         barrier_nospec();                                       \
 314         __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \
 315         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 316                                                                 \
 317         __gu_err;                                               \
 318 })
 319
 320
 321 /* more complex routines */
 322
 323 extern unsigned long __copy_tofrom_user(void __user *to,
 324                 const void __user *from, unsigned long size);
 325
 326 #ifdef __powerpc64__
 327 static inline unsigned long
 328 raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
 329 {
 330         unsigned long ret;
 331
 332         barrier_nospec();
 333         allow_user_access(to, from, n);
 334         ret = __copy_tofrom_user(to, from, n);
 335         prevent_user_access(to, from, n);
 336         return ret;
 337 }
 338 #endif /* __powerpc64__ */
 339
 340 static inline unsigned long raw_copy_from_user(void *to,
 341                 const void __user *from, unsigned long n)
 342 {
 343         unsigned long ret;
 344         if (__builtin_constant_p(n) && (n <= 8)) {
 345                 ret = 1;
 346
 347                 switch (n) {
 348                 case 1:
 349                         barrier_nospec();
 350                         __get_user_size(*(u8 *)to, from, 1, ret);
 351                         break;
 352                 case 2:
 353                         barrier_nospec();
 354                         __get_user_size(*(u16 *)to, from, 2, ret);
 355                         break;
 356                 case 4:
 357                         barrier_nospec();
 358                         __get_user_size(*(u32 *)to, from, 4, ret);
 359                         break;
 360                 case 8:
 361                         barrier_nospec();
 362                         __get_user_size(*(u64 *)to, from, 8, ret);
 363                         break;
 364                 }
 365                 if (ret == 0)
 366                         return 0;
 367         }
 368
 369         barrier_nospec();
 370         allow_read_from_user(from, n);
 371         ret = __copy_tofrom_user((__force void __user *)to, from, n);
 372         prevent_read_from_user(from, n);
 373         return ret;
 374 }
 375
 376 static inline unsigned long
 377 raw_copy_to_user_allowed(void __user *to, const void *from, unsigned long n)
 378 {
 379         if (__builtin_constant_p(n) && (n <= 8)) {
 380                 unsigned long ret = 1;
 381
 382                 switch (n) {
 383                 case 1:
 384                         __put_user_size_allowed(*(u8 *)from, (u8 __user *)to, 1, ret);
 385                         break;
 386                 case 2:
 387                         __put_user_size_allowed(*(u16 *)from, (u16 __user *)to, 2, ret);
 388                         break;
 389                 case 4:
 390                         __put_user_size_allowed(*(u32 *)from, (u32 __user *)to, 4, ret);
 391                         break;
 392                 case 8:
 393                         __put_user_size_allowed(*(u64 *)from, (u64 __user *)to, 8, ret);
 394                         break;
 395                 }
 396                 if (ret == 0)
 397                         return 0;
 398         }
 399
 400         return __copy_tofrom_user(to, (__force const void __user *)from, n);
 401 }
 402
 403 static inline unsigned long
 404 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 405 {
 406         unsigned long ret;
 407
 408         allow_write_to_user(to, n);
 409         ret = raw_copy_to_user_allowed(to, from, n);
 410         prevent_write_to_user(to, n);
 411         return ret;
 412 }
 413
 414 unsigned long __arch_clear_user(void __user *addr, unsigned long size);
 415
 416 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 417 {
 418         unsigned long ret = size;
 419         might_fault();
 420         if (likely(access_ok(VERIFY_WRITE, addr, size))) {
 421                 allow_write_to_user(addr, size);
 422                 ret = __arch_clear_user(addr, size);
 423                 prevent_write_to_user(addr, size);
 424         }
 425         return ret;
 426 }
 427
 428 static inline unsigned long __clear_user(void __user *addr, unsigned long size)
 429 {
 430         return clear_user(addr, size);
 431 }
 432
 433 extern long strncpy_from_user(char *dst, const char __user *src, long count);
 434 extern __must_check long strnlen_user(const char __user *str, long n);
 435
 436
 437 #define user_access_begin(type, ptr, len) access_ok(type, ptr, len)
 438 #define user_access_end()                 prevent_user_access(NULL, NULL, ~0ul)
 439
 440 #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
 441 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
 442 #define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e)
 443 #define unsafe_copy_to_user(d, s, l, e) \
 444         unsafe_op_wrap(raw_copy_to_user_allowed(d, s, l), e)
 445
 446 #endif  /* _ARCH_POWERPC_UACCESS_H */