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/ppc_asm.h>
   6 #include <asm/processor.h>
   7 #include <asm/page.h>
   8 #include <asm/extable.h>
   9 #include <asm/kup.h>
  10
  11 /*
  12  * The fs value determines whether argument validity checking should be
  13  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  14  * get_fs() == KERNEL_DS, checking is bypassed.
  15  *
  16  * For historical reasons, these macros are grossly misnamed.
  17  *
  18  * The fs/ds values are now the highest legal address in the "segment".
  19  * This simplifies the checking in the routines below.
  20  */
  21
  22 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  23
  24 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
  25 #ifdef __powerpc64__
  26 /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
  27 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
  28 #else
  29 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
  30 #endif
  31
  32 #define get_fs()        (current->thread.addr_limit)
  33
  34 static inline void set_fs(mm_segment_t fs)
  35 {
  36         current->thread.addr_limit = fs;
  37         /* On user-mode return check addr_limit (fs) is correct */
  38         set_thread_flag(TIF_FSCHECK);
  39 }
  40
  41 #define segment_eq(a, b)        ((a).seg == (b).seg)
  42
  43 #define user_addr_max() (get_fs().seg)
  44
  45 #ifdef __powerpc64__
  46 /*
  47  * This check is sufficient because there is a large enough
  48  * gap between user addresses and the kernel addresses
  49  */
  50 #define __access_ok(addr, size, segment)        \
  51         (((addr) <= (segment).seg) && ((size) <= (segment).seg))
  52
  53 #else
  54
  55 static inline int __access_ok(unsigned long addr, unsigned long size,
  56                         mm_segment_t seg)
  57 {
  58         if (addr > seg.seg)
  59                 return 0;
  60         return (size == 0 || size - 1 <= seg.seg - addr);
  61 }
  62
  63 #endif
  64
  65 #define access_ok(addr, size)           \
  66         (__chk_user_ptr(addr),          \
  67          __access_ok((__force unsigned long)(addr), (size), get_fs()))
  68
  69 /*
  70  * These are the main single-value transfer routines.  They automatically
  71  * use the right size if we just have the right pointer type.
  72  *
  73  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  74  * and yet we don't want to do any pointers, because that is too much
  75  * of a performance impact. Thus we have a few rather ugly macros here,
  76  * and hide all the ugliness from the user.
  77  *
  78  * The "__xxx" versions of the user access functions are versions that
  79  * do not verify the address space, that must have been done previously
  80  * with a separate "access_ok()" call (this is used when we do multiple
  81  * accesses to the same area of user memory).
  82  *
  83  * As we use the same address space for kernel and user data on the
  84  * PowerPC, we can just do these as direct assignments.  (Of course, the
  85  * exception handling means that it's no longer "just"...)
  86  *
  87  */
  88 #define get_user(x, ptr) \
  89         __get_user_check((x), (ptr), sizeof(*(ptr)))
  90 #define put_user(x, ptr) \
  91         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  92
  93 #define __get_user(x, ptr) \
  94         __get_user_nocheck((x), (ptr), sizeof(*(ptr)), true)
  95 #define __put_user(x, ptr) \
  96         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), true)
  97
  98 #define __get_user_allowed(x, ptr) \
  99         __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false)
 100 #define __put_user_allowed(x, ptr) \
 101         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), false)
 102
 103 #define __get_user_inatomic(x, ptr) \
 104         __get_user_nosleep((x), (ptr), sizeof(*(ptr)))
 105 #define __put_user_inatomic(x, ptr) \
 106         __put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 107
 108 extern long __put_user_bad(void);
 109
 110 /*
 111  * We don't tell gcc that we are accessing memory, but this is OK
 112  * because we do not write to any memory gcc knows about, so there
 113  * are no aliasing issues.
 114  */
 115 #define __put_user_asm(x, addr, err, op)                        \
 116         __asm__ __volatile__(                                   \
 117                 "1:     " op " %1,0(%2) # put_user\n"           \
 118                 "2:\n"                                          \
 119                 ".section .fixup,\"ax\"\n"                      \
 120                 "3:     li %0,%3\n"                             \
 121                 "       b 2b\n"                                 \
 122                 ".previous\n"                                   \
 123                 EX_TABLE(1b, 3b)                                \
 124                 : "=r" (err)                                    \
 125                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 126
 127 #ifdef __powerpc64__
 128 #define __put_user_asm2(x, ptr, retval)                         \
 129           __put_user_asm(x, ptr, retval, "std")
 130 #else /* __powerpc64__ */
 131 #define __put_user_asm2(x, addr, err)                           \
 132         __asm__ __volatile__(                                   \
 133                 "1:     stw %1,0(%2)\n"                         \
 134                 "2:     stw %1+1,4(%2)\n"                       \
 135                 "3:\n"                                          \
 136                 ".section .fixup,\"ax\"\n"                      \
 137                 "4:     li %0,%3\n"                             \
 138                 "       b 3b\n"                                 \
 139                 ".previous\n"                                   \
 140                 EX_TABLE(1b, 4b)                                \
 141                 EX_TABLE(2b, 4b)                                \
 142                 : "=r" (err)                                    \
 143                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 144 #endif /* __powerpc64__ */
 145
 146 #define __put_user_size_allowed(x, ptr, size, retval)           \
 147 do {                                                            \
 148         retval = 0;                                             \
 149         switch (size) {                                         \
 150           case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
 151           case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
 152           case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
 153           case 8: __put_user_asm2(x, ptr, retval); break;       \
 154           default: __put_user_bad();                            \
 155         }                                                       \
 156 } while (0)
 157
 158 #define __put_user_size(x, ptr, size, retval)                   \
 159 do {                                                            \
 160         allow_write_to_user(ptr, size);                         \
 161         __put_user_size_allowed(x, ptr, size, retval);          \
 162         prevent_write_to_user(ptr, size);                       \
 163 } while (0)
 164
 165 #define __put_user_nocheck(x, ptr, size, do_allow)                      \
 166 ({                                                              \
 167         long __pu_err;                                          \
 168         __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
 169         if (!is_kernel_addr((unsigned long)__pu_addr))          \
 170                 might_fault();                                  \
 171         __chk_user_ptr(ptr);                                    \
 172         if (do_allow)                                                           \
 173                 __put_user_size((x), __pu_addr, (size), __pu_err);              \
 174         else                                                                    \
 175                 __put_user_size_allowed((x), __pu_addr, (size), __pu_err);      \
 176         __pu_err;                                               \
 177 })
 178
 179 #define __put_user_check(x, ptr, size)                                  \
 180 ({                                                                      \
 181         long __pu_err = -EFAULT;                                        \
 182         __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
 183         might_fault();                                                  \
 184         if (access_ok(__pu_addr, size))                 \
 185                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
 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         __chk_user_ptr(ptr);                                    \
 194         __put_user_size((x), __pu_addr, (size), __pu_err);      \
 195         __pu_err;                                               \
 196 })
 197
 198
 199 extern long __get_user_bad(void);
 200
 201 /*
 202  * This does an atomic 128 byte aligned load from userspace.
 203  * Upto caller to do enable_kernel_vmx() before calling!
 204  */
 205 #define __get_user_atomic_128_aligned(kaddr, uaddr, err)                \
 206         __asm__ __volatile__(                           \
 207                 "1:     lvx  0,0,%1     # get user\n"   \
 208                 "       stvx 0,0,%2     # put kernel\n" \
 209                 "2:\n"                                  \
 210                 ".section .fixup,\"ax\"\n"              \
 211                 "3:     li %0,%3\n"                     \
 212                 "       b 2b\n"                         \
 213                 ".previous\n"                           \
 214                 EX_TABLE(1b, 3b)                        \
 215                 : "=r" (err)                    \
 216                 : "b" (uaddr), "b" (kaddr), "i" (-EFAULT), "0" (err))
 217
 218 #define __get_user_asm(x, addr, err, op)                \
 219         __asm__ __volatile__(                           \
 220                 "1:     "op" %1,0(%2)   # get_user\n"   \
 221                 "2:\n"                                  \
 222                 ".section .fixup,\"ax\"\n"              \
 223                 "3:     li %0,%3\n"                     \
 224                 "       li %1,0\n"                      \
 225                 "       b 2b\n"                         \
 226                 ".previous\n"                           \
 227                 EX_TABLE(1b, 3b)                        \
 228                 : "=r" (err), "=r" (x)                  \
 229                 : "b" (addr), "i" (-EFAULT), "0" (err))
 230
 231 #ifdef __powerpc64__
 232 #define __get_user_asm2(x, addr, err)                   \
 233         __get_user_asm(x, addr, err, "ld")
 234 #else /* __powerpc64__ */
 235 #define __get_user_asm2(x, addr, err)                   \
 236         __asm__ __volatile__(                           \
 237                 "1:     lwz %1,0(%2)\n"                 \
 238                 "2:     lwz %1+1,4(%2)\n"               \
 239                 "3:\n"                                  \
 240                 ".section .fixup,\"ax\"\n"              \
 241                 "4:     li %0,%3\n"                     \
 242                 "       li %1,0\n"                      \
 243                 "       li %1+1,0\n"                    \
 244                 "       b 3b\n"                         \
 245                 ".previous\n"                           \
 246                 EX_TABLE(1b, 4b)                        \
 247                 EX_TABLE(2b, 4b)                        \
 248                 : "=r" (err), "=&r" (x)                 \
 249                 : "b" (addr), "i" (-EFAULT), "0" (err))
 250 #endif /* __powerpc64__ */
 251
 252 #define __get_user_size_allowed(x, ptr, size, retval)           \
 253 do {                                                            \
 254         retval = 0;                                             \
 255         __chk_user_ptr(ptr);                                    \
 256         if (size > sizeof(x))                                   \
 257                 (x) = __get_user_bad();                         \
 258         switch (size) {                                         \
 259         case 1: __get_user_asm(x, ptr, retval, "lbz"); break;   \
 260         case 2: __get_user_asm(x, ptr, retval, "lhz"); break;   \
 261         case 4: __get_user_asm(x, ptr, retval, "lwz"); break;   \
 262         case 8: __get_user_asm2(x, ptr, retval);  break;        \
 263         default: (x) = __get_user_bad();                        \
 264         }                                                       \
 265 } while (0)
 266
 267 #define __get_user_size(x, ptr, size, retval)                   \
 268 do {                                                            \
 269         allow_read_from_user(ptr, size);                        \
 270         __get_user_size_allowed(x, ptr, size, retval);          \
 271         prevent_read_from_user(ptr, size);                      \
 272 } while (0)
 273
 274 /*
 275  * This is a type: either unsigned long, if the argument fits into
 276  * that type, or otherwise unsigned long long.
 277  */
 278 #define __long_type(x) \
 279         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 280
 281 #define __get_user_nocheck(x, ptr, size, do_allow)                      \
 282 ({                                                              \
 283         long __gu_err;                                          \
 284         __long_type(*(ptr)) __gu_val;                           \
 285         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 286         __chk_user_ptr(ptr);                                    \
 287         if (!is_kernel_addr((unsigned long)__gu_addr))          \
 288                 might_fault();                                  \
 289         barrier_nospec();                                       \
 290         if (do_allow)                                                           \
 291                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err);         \
 292         else                                                                    \
 293                 __get_user_size_allowed(__gu_val, __gu_addr, (size), __gu_err); \
 294         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 295         __gu_err;                                               \
 296 })
 297
 298 #define __get_user_check(x, ptr, size)                                  \
 299 ({                                                                      \
 300         long __gu_err = -EFAULT;                                        \
 301         __long_type(*(ptr)) __gu_val = 0;                               \
 302         __typeof__(*(ptr)) __user *__gu_addr = (ptr);           \
 303         might_fault();                                                  \
 304         if (access_ok(__gu_addr, (size))) {             \
 305                 barrier_nospec();                                       \
 306                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 307         }                                                               \
 308         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 309         __gu_err;                                                       \
 310 })
 311
 312 #define __get_user_nosleep(x, ptr, size)                        \
 313 ({                                                              \
 314         long __gu_err;                                          \
 315         __long_type(*(ptr)) __gu_val;                           \
 316         __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
 317         __chk_user_ptr(ptr);                                    \
 318         barrier_nospec();                                       \
 319         __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 320         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 321         __gu_err;                                               \
 322 })
 323
 324
 325 /* more complex routines */
 326
 327 extern unsigned long __copy_tofrom_user(void __user *to,
 328                 const void __user *from, unsigned long size);
 329
 330 #ifdef __powerpc64__
 331 static inline unsigned long
 332 raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
 333 {
 334         unsigned long ret;
 335
 336         barrier_nospec();
 337         allow_read_write_user(to, from, n);
 338         ret = __copy_tofrom_user(to, from, n);
 339         prevent_read_write_user(to, from, n);
 340         return ret;
 341 }
 342 #endif /* __powerpc64__ */
 343
 344 static inline unsigned long raw_copy_from_user(void *to,
 345                 const void __user *from, unsigned long n)
 346 {
 347         unsigned long ret;
 348         if (__builtin_constant_p(n) && (n <= 8)) {
 349                 ret = 1;
 350
 351                 switch (n) {
 352                 case 1:
 353                         barrier_nospec();
 354                         __get_user_size(*(u8 *)to, from, 1, ret);
 355                         break;
 356                 case 2:
 357                         barrier_nospec();
 358                         __get_user_size(*(u16 *)to, from, 2, ret);
 359                         break;
 360                 case 4:
 361                         barrier_nospec();
 362                         __get_user_size(*(u32 *)to, from, 4, ret);
 363                         break;
 364                 case 8:
 365                         barrier_nospec();
 366                         __get_user_size(*(u64 *)to, from, 8, ret);
 367                         break;
 368                 }
 369                 if (ret == 0)
 370                         return 0;
 371         }
 372
 373         barrier_nospec();
 374         allow_read_from_user(from, n);
 375         ret = __copy_tofrom_user((__force void __user *)to, from, n);
 376         prevent_read_from_user(from, n);
 377         return ret;
 378 }
 379
 380 static inline unsigned long
 381 raw_copy_to_user_allowed(void __user *to, const void *from, unsigned long n)
 382 {
 383         if (__builtin_constant_p(n) && (n <= 8)) {
 384                 unsigned long ret = 1;
 385
 386                 switch (n) {
 387                 case 1:
 388                         __put_user_size_allowed(*(u8 *)from, (u8 __user *)to, 1, ret);
 389                         break;
 390                 case 2:
 391                         __put_user_size_allowed(*(u16 *)from, (u16 __user *)to, 2, ret);
 392                         break;
 393                 case 4:
 394                         __put_user_size_allowed(*(u32 *)from, (u32 __user *)to, 4, ret);
 395                         break;
 396                 case 8:
 397                         __put_user_size_allowed(*(u64 *)from, (u64 __user *)to, 8, ret);
 398                         break;
 399                 }
 400                 if (ret == 0)
 401                         return 0;
 402         }
 403
 404         return __copy_tofrom_user(to, (__force const void __user *)from, n);
 405 }
 406
 407 static inline unsigned long
 408 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 409 {
 410         unsigned long ret;
 411
 412         allow_write_to_user(to, n);
 413         ret = raw_copy_to_user_allowed(to, from, n);
 414         prevent_write_to_user(to, n);
 415         return ret;
 416 }
 417
 418 static __always_inline unsigned long __must_check
 419 copy_to_user_mcsafe(void __user *to, const void *from, unsigned long n)
 420 {
 421         if (likely(check_copy_size(from, n, true))) {
 422                 if (access_ok(to, n)) {
 423                         allow_write_to_user(to, n);
 424                         n = memcpy_mcsafe((void *)to, from, n);
 425                         prevent_write_to_user(to, n);
 426                 }
 427         }
 428
 429         return n;
 430 }
 431
 432 unsigned long __arch_clear_user(void __user *addr, unsigned long size);
 433
 434 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 435 {
 436         unsigned long ret = size;
 437         might_fault();
 438         if (likely(access_ok(addr, size))) {
 439                 allow_write_to_user(addr, size);
 440                 ret = __arch_clear_user(addr, size);
 441                 prevent_write_to_user(addr, size);
 442         }
 443         return ret;
 444 }
 445
 446 static inline unsigned long __clear_user(void __user *addr, unsigned long size)
 447 {
 448         return clear_user(addr, size);
 449 }
 450
 451 extern long strncpy_from_user(char *dst, const char __user *src, long count);
 452 extern __must_check long strnlen_user(const char __user *str, long n);
 453
 454 extern long __copy_from_user_flushcache(void *dst, const void __user *src,
 455                 unsigned size);
 456 extern void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
 457                            size_t len);
 458
 459 static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
 460 {
 461         if (unlikely(!access_ok(ptr, len)))
 462                 return false;
 463         allow_read_write_user((void __user *)ptr, ptr, len);
 464         return true;
 465 }
 466 #define user_access_begin       user_access_begin
 467 #define user_access_end         prevent_current_access_user
 468 #define user_access_save        prevent_user_access_return
 469 #define user_access_restore     restore_user_access
 470
 471 #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
 472 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
 473 #define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e)
 474 #define unsafe_copy_to_user(d, s, l, e) \
 475         unsafe_op_wrap(raw_copy_to_user_allowed(d, s, l), e)
 476
 477 #endif  /* _ARCH_POWERPC_UACCESS_H */