arch/x86/include/asm/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_UACCESS_H
   3 #define _ASM_X86_UACCESS_H
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/compiler.h>
   8 #include <linux/kasan-checks.h>
   9 #include <linux/string.h>
  10 #include <asm/asm.h>
  11 #include <asm/page.h>
  12 #include <asm/smap.h>
  13 #include <asm/extable.h>
  14
  15 /*
  16  * The fs value determines whether argument validity checking should be
  17  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  18  * get_fs() == KERNEL_DS, checking is bypassed.
  19  *
  20  * For historical reasons, these macros are grossly misnamed.
  21  */
  22
  23 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  24
  25 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  26 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  27
  28 #define get_fs()        (current->thread.addr_limit)
  29 static inline void set_fs(mm_segment_t fs)
  30 {
  31         current->thread.addr_limit = fs;
  32         /* On user-mode return, check fs is correct */
  33         set_thread_flag(TIF_FSCHECK);
  34 }
  35
  36 #define segment_eq(a, b)        ((a).seg == (b).seg)
  37 #define user_addr_max() (current->thread.addr_limit.seg)
  38
  39 /*
  40  * Test whether a block of memory is a valid user space address.
  41  * Returns 0 if the range is valid, nonzero otherwise.
  42  */
  43 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  44 {
  45         /*
  46          * If we have used "sizeof()" for the size,
  47          * we know it won't overflow the limit (but
  48          * it might overflow the 'addr', so it's
  49          * important to subtract the size from the
  50          * limit, not add it to the address).
  51          */
  52         if (__builtin_constant_p(size))
  53                 return unlikely(addr > limit - size);
  54
  55         /* Arbitrary sizes? Be careful about overflow */
  56         addr += size;
  57         if (unlikely(addr < size))
  58                 return true;
  59         return unlikely(addr > limit);
  60 }
  61
  62 #define __range_not_ok(addr, size, limit)                               \
  63 ({                                                                      \
  64         __chk_user_ptr(addr);                                           \
  65         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  66 })
  67
  68 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  69 static inline bool pagefault_disabled(void);
  70 # define WARN_ON_IN_IRQ()       \
  71         WARN_ON_ONCE(!in_task() && !pagefault_disabled())
  72 #else
  73 # define WARN_ON_IN_IRQ()
  74 #endif
  75
  76 /**
  77  * access_ok - Checks if a user space pointer is valid
  78  * @addr: User space pointer to start of block to check
  79  * @size: Size of block to check
  80  *
  81  * Context: User context only. This function may sleep if pagefaults are
  82  *          enabled.
  83  *
  84  * Checks if a pointer to a block of memory in user space is valid.
  85  *
  86  * Note that, depending on architecture, this function probably just
  87  * checks that the pointer is in the user space range - after calling
  88  * this function, memory access functions may still return -EFAULT.
  89  *
  90  * Return: true (nonzero) if the memory block may be valid, false (zero)
  91  * if it is definitely invalid.
  92  */
  93 #define access_ok(addr, size)                                   \
  94 ({                                                                      \
  95         WARN_ON_IN_IRQ();                                               \
  96         likely(!__range_not_ok(addr, size, user_addr_max()));           \
  97 })
  98
  99 /*
 100  * These are the main single-value transfer routines.  They automatically
 101  * use the right size if we just have the right pointer type.
 102  *
 103  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 104  * and yet we don't want to do any pointers, because that is too much
 105  * of a performance impact. Thus we have a few rather ugly macros here,
 106  * and hide all the ugliness from the user.
 107  *
 108  * The "__xxx" versions of the user access functions are versions that
 109  * do not verify the address space, that must have been done previously
 110  * with a separate "access_ok()" call (this is used when we do multiple
 111  * accesses to the same area of user memory).
 112  */
 113
 114 extern int __get_user_1(void);
 115 extern int __get_user_2(void);
 116 extern int __get_user_4(void);
 117 extern int __get_user_8(void);
 118 extern int __get_user_bad(void);
 119
 120 #define __uaccess_begin() stac()
 121 #define __uaccess_end()   clac()
 122 #define __uaccess_begin_nospec()        \
 123 ({                                      \
 124         stac();                         \
 125         barrier_nospec();               \
 126 })
 127
 128 /*
 129  * This is a type: either unsigned long, if the argument fits into
 130  * that type, or otherwise unsigned long long.
 131  */
 132 #define __inttype(x) \
 133 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 134
 135 /**
 136  * get_user - Get a simple variable from user space.
 137  * @x:   Variable to store result.
 138  * @ptr: Source address, in user space.
 139  *
 140  * Context: User context only. This function may sleep if pagefaults are
 141  *          enabled.
 142  *
 143  * This macro copies a single simple variable from user space to kernel
 144  * space.  It supports simple types like char and int, but not larger
 145  * data types like structures or arrays.
 146  *
 147  * @ptr must have pointer-to-simple-variable type, and the result of
 148  * dereferencing @ptr must be assignable to @x without a cast.
 149  *
 150  * Return: zero on success, or -EFAULT on error.
 151  * On error, the variable @x is set to zero.
 152  */
 153 /*
 154  * Careful: we have to cast the result to the type of the pointer
 155  * for sign reasons.
 156  *
 157  * The use of _ASM_DX as the register specifier is a bit of a
 158  * simplification, as gcc only cares about it as the starting point
 159  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 160  * (%ecx being the next register in gcc's x86 register sequence), and
 161  * %rdx on 64 bits.
 162  *
 163  * Clang/LLVM cares about the size of the register, but still wants
 164  * the base register for something that ends up being a pair.
 165  */
 166 #define get_user(x, ptr)                                                \
 167 ({                                                                      \
 168         int __ret_gu;                                                   \
 169         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 170         __chk_user_ptr(ptr);                                            \
 171         might_fault();                                                  \
 172         asm volatile("call __get_user_%P4"                              \
 173                      : "=a" (__ret_gu), "=r" (__val_gu),                \
 174                         ASM_CALL_CONSTRAINT                             \
 175                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 176         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 177         __builtin_expect(__ret_gu, 0);                                  \
 178 })
 179
 180 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 181         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 182                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 183
 184
 185
 186 #ifdef CONFIG_X86_32
 187 #define __put_user_goto_u64(x, addr, label)                     \
 188         asm_volatile_goto("\n"                                  \
 189                      "1:        movl %%eax,0(%1)\n"             \
 190                      "2:        movl %%edx,4(%1)\n"             \
 191                      _ASM_EXTABLE_UA(1b, %l2)                   \
 192                      _ASM_EXTABLE_UA(2b, %l2)                   \
 193                      : : "A" (x), "r" (addr)                    \
 194                      : : label)
 195
 196 #define __put_user_asm_ex_u64(x, addr)                                  \
 197         asm volatile("\n"                                               \
 198                      "1:        movl %%eax,0(%1)\n"                     \
 199                      "2:        movl %%edx,4(%1)\n"                     \
 200                      "3:"                                               \
 201                      _ASM_EXTABLE_EX(1b, 2b)                            \
 202                      _ASM_EXTABLE_EX(2b, 3b)                            \
 203                      : : "A" (x), "r" (addr))
 204
 205 #define __put_user_x8(x, ptr, __ret_pu)                         \
 206         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 207                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 208 #else
 209 #define __put_user_goto_u64(x, ptr, label) \
 210         __put_user_goto(x, ptr, "q", "", "er", label)
 211 #define __put_user_asm_ex_u64(x, addr)  \
 212         __put_user_asm_ex(x, addr, "q", "", "er")
 213 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 214 #endif
 215
 216 extern void __put_user_bad(void);
 217
 218 /*
 219  * Strange magic calling convention: pointer in %ecx,
 220  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 221  */
 222 extern void __put_user_1(void);
 223 extern void __put_user_2(void);
 224 extern void __put_user_4(void);
 225 extern void __put_user_8(void);
 226
 227 /**
 228  * put_user - Write a simple value into user space.
 229  * @x:   Value to copy to user space.
 230  * @ptr: Destination address, in user space.
 231  *
 232  * Context: User context only. This function may sleep if pagefaults are
 233  *          enabled.
 234  *
 235  * This macro copies a single simple value from kernel space to user
 236  * space.  It supports simple types like char and int, but not larger
 237  * data types like structures or arrays.
 238  *
 239  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 240  * to the result of dereferencing @ptr.
 241  *
 242  * Return: zero on success, or -EFAULT on error.
 243  */
 244 #define put_user(x, ptr)                                        \
 245 ({                                                              \
 246         int __ret_pu;                                           \
 247         __typeof__(*(ptr)) __pu_val;                            \
 248         __chk_user_ptr(ptr);                                    \
 249         might_fault();                                          \
 250         __pu_val = x;                                           \
 251         switch (sizeof(*(ptr))) {                               \
 252         case 1:                                                 \
 253                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 254                 break;                                          \
 255         case 2:                                                 \
 256                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 257                 break;                                          \
 258         case 4:                                                 \
 259                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 260                 break;                                          \
 261         case 8:                                                 \
 262                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 263                 break;                                          \
 264         default:                                                \
 265                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 266                 break;                                          \
 267         }                                                       \
 268         __builtin_expect(__ret_pu, 0);                          \
 269 })
 270
 271 #define __put_user_size(x, ptr, size, label)                            \
 272 do {                                                                    \
 273         __chk_user_ptr(ptr);                                            \
 274         switch (size) {                                                 \
 275         case 1:                                                         \
 276                 __put_user_goto(x, ptr, "b", "b", "iq", label); \
 277                 break;                                                  \
 278         case 2:                                                         \
 279                 __put_user_goto(x, ptr, "w", "w", "ir", label);         \
 280                 break;                                                  \
 281         case 4:                                                         \
 282                 __put_user_goto(x, ptr, "l", "k", "ir", label);         \
 283                 break;                                                  \
 284         case 8:                                                         \
 285                 __put_user_goto_u64(x, ptr, label);                     \
 286                 break;                                                  \
 287         default:                                                        \
 288                 __put_user_bad();                                       \
 289         }                                                               \
 290 } while (0)
 291
 292 /*
 293  * This doesn't do __uaccess_begin/end - the exception handling
 294  * around it must do that.
 295  */
 296 #define __put_user_size_ex(x, ptr, size)                                \
 297 do {                                                                    \
 298         __chk_user_ptr(ptr);                                            \
 299         switch (size) {                                                 \
 300         case 1:                                                         \
 301                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 302                 break;                                                  \
 303         case 2:                                                         \
 304                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 305                 break;                                                  \
 306         case 4:                                                         \
 307                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 308                 break;                                                  \
 309         case 8:                                                         \
 310                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 311                 break;                                                  \
 312         default:                                                        \
 313                 __put_user_bad();                                       \
 314         }                                                               \
 315 } while (0)
 316
 317 #ifdef CONFIG_X86_32
 318 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 319 ({                                                                      \
 320         __typeof__(ptr) __ptr = (ptr);                                  \
 321         asm volatile("\n"                                       \
 322                      "1:        movl %2,%%eax\n"                        \
 323                      "2:        movl %3,%%edx\n"                        \
 324                      "3:\n"                             \
 325                      ".section .fixup,\"ax\"\n"                         \
 326                      "4:        mov %4,%0\n"                            \
 327                      "  xorl %%eax,%%eax\n"                             \
 328                      "  xorl %%edx,%%edx\n"                             \
 329                      "  jmp 3b\n"                                       \
 330                      ".previous\n"                                      \
 331                      _ASM_EXTABLE_UA(1b, 4b)                            \
 332                      _ASM_EXTABLE_UA(2b, 4b)                            \
 333                      : "=r" (retval), "=&A"(x)                          \
 334                      : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),  \
 335                        "i" (errret), "0" (retval));                     \
 336 })
 337
 338 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 339 #else
 340 #define __get_user_asm_u64(x, ptr, retval, errret) \
 341          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 342 #define __get_user_asm_ex_u64(x, ptr) \
 343          __get_user_asm_ex(x, ptr, "q", "", "=r")
 344 #endif
 345
 346 #define __get_user_size(x, ptr, size, retval, errret)                   \
 347 do {                                                                    \
 348         retval = 0;                                                     \
 349         __chk_user_ptr(ptr);                                            \
 350         switch (size) {                                                 \
 351         case 1:                                                         \
 352                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 353                 break;                                                  \
 354         case 2:                                                         \
 355                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 356                 break;                                                  \
 357         case 4:                                                         \
 358                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 359                 break;                                                  \
 360         case 8:                                                         \
 361                 __get_user_asm_u64(x, ptr, retval, errret);             \
 362                 break;                                                  \
 363         default:                                                        \
 364                 (x) = __get_user_bad();                                 \
 365         }                                                               \
 366 } while (0)
 367
 368 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 369         asm volatile("\n"                                               \
 370                      "1:        mov"itype" %2,%"rtype"1\n"              \
 371                      "2:\n"                                             \
 372                      ".section .fixup,\"ax\"\n"                         \
 373                      "3:        mov %3,%0\n"                            \
 374                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 375                      "  jmp 2b\n"                                       \
 376                      ".previous\n"                                      \
 377                      _ASM_EXTABLE_UA(1b, 3b)                            \
 378                      : "=r" (err), ltype(x)                             \
 379                      : "m" (__m(addr)), "i" (errret), "0" (err))
 380
 381 /*
 382  * This doesn't do __uaccess_begin/end - the exception handling
 383  * around it must do that.
 384  */
 385 #define __get_user_size_ex(x, ptr, size)                                \
 386 do {                                                                    \
 387         __chk_user_ptr(ptr);                                            \
 388         switch (size) {                                                 \
 389         case 1:                                                         \
 390                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 391                 break;                                                  \
 392         case 2:                                                         \
 393                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 394                 break;                                                  \
 395         case 4:                                                         \
 396                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 397                 break;                                                  \
 398         case 8:                                                         \
 399                 __get_user_asm_ex_u64(x, ptr);                          \
 400                 break;                                                  \
 401         default:                                                        \
 402                 (x) = __get_user_bad();                                 \
 403         }                                                               \
 404 } while (0)
 405
 406 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 407         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 408                      "2:\n"                                             \
 409                      ".section .fixup,\"ax\"\n"                         \
 410                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 411                      "  jmp 2b\n"                                       \
 412                      ".previous\n"                                      \
 413                      _ASM_EXTABLE_EX(1b, 3b)                            \
 414                      : ltype(x) : "m" (__m(addr)))
 415
 416 #define __put_user_nocheck(x, ptr, size)                        \
 417 ({                                                              \
 418         __label__ __pu_label;                                   \
 419         int __pu_err = -EFAULT;                                 \
 420         __typeof__(*(ptr)) __pu_val = (x);                      \
 421         __typeof__(ptr) __pu_ptr = (ptr);                       \
 422         __typeof__(size) __pu_size = (size);                    \
 423         __uaccess_begin();                                      \
 424         __put_user_size(__pu_val, __pu_ptr, __pu_size, __pu_label);     \
 425         __pu_err = 0;                                           \
 426 __pu_label:                                                     \
 427         __uaccess_end();                                        \
 428         __builtin_expect(__pu_err, 0);                          \
 429 })
 430
 431 #define __get_user_nocheck(x, ptr, size)                                \
 432 ({                                                                      \
 433         int __gu_err;                                                   \
 434         __inttype(*(ptr)) __gu_val;                                     \
 435         __typeof__(ptr) __gu_ptr = (ptr);                               \
 436         __typeof__(size) __gu_size = (size);                            \
 437         __uaccess_begin_nospec();                                       \
 438         __get_user_size(__gu_val, __gu_ptr, __gu_size, __gu_err, -EFAULT);      \
 439         __uaccess_end();                                                \
 440         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 441         __builtin_expect(__gu_err, 0);                                  \
 442 })
 443
 444 #ifdef CONFIG_CC_HAS_ASM_GOTO_TIED_OUTPUT
 445 #define __try_cmpxchg_user_asm(itype, ltype, _ptr, _pold, _new, label)  ({ \
 446         bool success;                                                   \
 447         __typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);              \
 448         __typeof__(*(_ptr)) __old = *_old;                              \
 449         __typeof__(*(_ptr)) __new = (_new);                             \
 450         asm_volatile_goto("\n"                                          \
 451                      "1: " LOCK_PREFIX "cmpxchg"itype" %[new], %[ptr]\n"\
 452                      _ASM_EXTABLE_UA(1b, %l[label])                     \
 453                      : CC_OUT(z) (success),                             \
 454                        [ptr] "+m" (*_ptr),                              \
 455                        [old] "+a" (__old)                               \
 456                      : [new] ltype (__new)                              \
 457                      : "memory"                                         \
 458                      : label);                                          \
 459         if (unlikely(!success))                                         \
 460                 *_old = __old;                                          \
 461         likely(success);                                        })
 462
 463 #ifdef CONFIG_X86_32
 464 #define __try_cmpxchg64_user_asm(_ptr, _pold, _new, label)      ({      \
 465         bool success;                                                   \
 466         __typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);              \
 467         __typeof__(*(_ptr)) __old = *_old;                              \
 468         __typeof__(*(_ptr)) __new = (_new);                             \
 469         asm_volatile_goto("\n"                                          \
 470                      "1: " LOCK_PREFIX "cmpxchg8b %[ptr]\n"             \
 471                      _ASM_EXTABLE_UA(1b, %l[label])                     \
 472                      : CC_OUT(z) (success),                             \
 473                        "+A" (__old),                                    \
 474                        [ptr] "+m" (*_ptr)                               \
 475                      : "b" ((u32)__new),                                \
 476                        "c" ((u32)((u64)__new >> 32))                    \
 477                      : "memory"                                         \
 478                      : label);                                          \
 479         if (unlikely(!success))                                         \
 480                 *_old = __old;                                          \
 481         likely(success);                                        })
 482 #endif // CONFIG_X86_32
 483 #else  // !CONFIG_CC_HAS_ASM_GOTO_TIED_OUTPUT
 484 #define __try_cmpxchg_user_asm(itype, ltype, _ptr, _pold, _new, label)  ({ \
 485         int __err = 0;                                                  \
 486         bool success;                                                   \
 487         __typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);              \
 488         __typeof__(*(_ptr)) __old = *_old;                              \
 489         __typeof__(*(_ptr)) __new = (_new);                             \
 490         asm volatile("\n"                                               \
 491                      "1: " LOCK_PREFIX "cmpxchg"itype" %[new], %[ptr]\n"\
 492                      CC_SET(z)                                          \
 493                      "2:\n"                                             \
 494                      _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG,  \
 495                                            %[errout])                   \
 496                      : CC_OUT(z) (success),                             \
 497                        [errout] "+r" (__err),                           \
 498                        [ptr] "+m" (*_ptr),                              \
 499                        [old] "+a" (__old)                               \
 500                      : [new] ltype (__new)                              \
 501                      : "memory");                                       \
 502         if (unlikely(__err))                                            \
 503                 goto label;                                             \
 504         if (unlikely(!success))                                         \
 505                 *_old = __old;                                          \
 506         likely(success);                                        })
 507
 508 #ifdef CONFIG_X86_32
 509 /*
 510  * Unlike the normal CMPXCHG, hardcode ECX for both success/fail and error.
 511  * There are only six GPRs available and four (EAX, EBX, ECX, and EDX) are
 512  * hardcoded by CMPXCHG8B, leaving only ESI and EDI.  If the compiler uses
 513  * both ESI and EDI for the memory operand, compilation will fail if the error
 514  * is an input+output as there will be no register available for input.
 515  */
 516 #define __try_cmpxchg64_user_asm(_ptr, _pold, _new, label)      ({      \
 517         int __result;                                                   \
 518         __typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);              \
 519         __typeof__(*(_ptr)) __old = *_old;                              \
 520         __typeof__(*(_ptr)) __new = (_new);                             \
 521         asm volatile("\n"                                               \
 522                      "1: " LOCK_PREFIX "cmpxchg8b %[ptr]\n"             \
 523                      "mov $0, %%ecx\n\t"                                \
 524                      "setz %%cl\n"                                      \
 525                      "2:\n"                                             \
 526                      _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %%ecx) \
 527                      : [result]"=c" (__result),                         \
 528                        "+A" (__old),                                    \
 529                        [ptr] "+m" (*_ptr)                               \
 530                      : "b" ((u32)__new),                                \
 531                        "c" ((u32)((u64)__new >> 32))                    \
 532                      : "memory", "cc");                                 \
 533         if (unlikely(__result < 0))                                     \
 534                 goto label;                                             \
 535         if (unlikely(!__result))                                        \
 536                 *_old = __old;                                          \
 537         likely(__result);                                       })
 538 #endif // CONFIG_X86_32
 539 #endif // CONFIG_CC_HAS_ASM_GOTO_TIED_OUTPUT
 540
 541 /* FIXME: this hack is definitely wrong -AK */
 542 struct __large_struct { unsigned long buf[100]; };
 543 #define __m(x) (*(struct __large_struct __user *)(x))
 544
 545 /*
 546  * Tell gcc we read from memory instead of writing: this is because
 547  * we do not write to any memory gcc knows about, so there are no
 548  * aliasing issues.
 549  */
 550 #define __put_user_goto(x, addr, itype, rtype, ltype, label)    \
 551         asm_volatile_goto("\n"                                          \
 552                 "1:     mov"itype" %"rtype"0,%1\n"                      \
 553                 _ASM_EXTABLE_UA(1b, %l2)                                        \
 554                 : : ltype(x), "m" (__m(addr))                           \
 555                 : : label)
 556
 557 #define __put_user_failed(x, addr, itype, rtype, ltype, errret)         \
 558         ({      __label__ __puflab;                                     \
 559                 int __pufret = errret;                                  \
 560                 __put_user_goto(x,addr,itype,rtype,ltype,__puflab);     \
 561                 __pufret = 0;                                           \
 562         __puflab: __pufret; })
 563
 564 #define __put_user_asm(x, addr, retval, itype, rtype, ltype, errret)    do {    \
 565         retval = __put_user_failed(x, addr, itype, rtype, ltype, errret);       \
 566 } while (0)
 567
 568 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 569         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 570                      "2:\n"                                             \
 571                      _ASM_EXTABLE_EX(1b, 2b)                            \
 572                      : : ltype(x), "m" (__m(addr)))
 573
 574 /*
 575  * uaccess_try and catch
 576  */
 577 #define uaccess_try     do {                                            \
 578         current->thread.uaccess_err = 0;                                \
 579         __uaccess_begin();                                              \
 580         barrier();
 581
 582 #define uaccess_try_nospec do {                                         \
 583         current->thread.uaccess_err = 0;                                \
 584         __uaccess_begin_nospec();                                       \
 585
 586 #define uaccess_catch(err)                                              \
 587         __uaccess_end();                                                \
 588         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 589 } while (0)
 590
 591 /**
 592  * __get_user - Get a simple variable from user space, with less checking.
 593  * @x:   Variable to store result.
 594  * @ptr: Source address, in user space.
 595  *
 596  * Context: User context only. This function may sleep if pagefaults are
 597  *          enabled.
 598  *
 599  * This macro copies a single simple variable from user space to kernel
 600  * space.  It supports simple types like char and int, but not larger
 601  * data types like structures or arrays.
 602  *
 603  * @ptr must have pointer-to-simple-variable type, and the result of
 604  * dereferencing @ptr must be assignable to @x without a cast.
 605  *
 606  * Caller must check the pointer with access_ok() before calling this
 607  * function.
 608  *
 609  * Return: zero on success, or -EFAULT on error.
 610  * On error, the variable @x is set to zero.
 611  */
 612
 613 #define __get_user(x, ptr)                                              \
 614         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 615
 616 /**
 617  * __put_user - Write a simple value into user space, with less checking.
 618  * @x:   Value to copy to user space.
 619  * @ptr: Destination address, in user space.
 620  *
 621  * Context: User context only. This function may sleep if pagefaults are
 622  *          enabled.
 623  *
 624  * This macro copies a single simple value from kernel space to user
 625  * space.  It supports simple types like char and int, but not larger
 626  * data types like structures or arrays.
 627  *
 628  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 629  * to the result of dereferencing @ptr.
 630  *
 631  * Caller must check the pointer with access_ok() before calling this
 632  * function.
 633  *
 634  * Return: zero on success, or -EFAULT on error.
 635  */
 636
 637 #define __put_user(x, ptr)                                              \
 638         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 639
 640 /*
 641  * {get|put}_user_try and catch
 642  *
 643  * get_user_try {
 644  *      get_user_ex(...);
 645  * } get_user_catch(err)
 646  */
 647 #define get_user_try            uaccess_try_nospec
 648 #define get_user_catch(err)     uaccess_catch(err)
 649
 650 #define get_user_ex(x, ptr)     do {                                    \
 651         unsigned long __gue_val;                                        \
 652         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 653         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 654 } while (0)
 655
 656 #define put_user_try            uaccess_try
 657 #define put_user_catch(err)     uaccess_catch(err)
 658
 659 #define put_user_ex(x, ptr)                                             \
 660         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 661
 662 extern unsigned long
 663 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 664 extern __must_check long
 665 strncpy_from_user(char *dst, const char __user *src, long count);
 666
 667 extern __must_check long strnlen_user(const char __user *str, long n);
 668
 669 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 670 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 671
 672 extern void __cmpxchg_wrong_size(void)
 673         __compiletime_error("Bad argument size for cmpxchg");
 674
 675 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 676 ({                                                                      \
 677         int __ret = 0;                                                  \
 678         __typeof__(*(ptr)) __old = (old);                               \
 679         __typeof__(*(ptr)) __new = (new);                               \
 680         __uaccess_begin_nospec();                                       \
 681         switch (size) {                                                 \
 682         case 1:                                                         \
 683         {                                                               \
 684                 asm volatile("\n"                                       \
 685                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 686                         "2:\n"                                          \
 687                         "\t.section .fixup, \"ax\"\n"                   \
 688                         "3:\tmov     %3, %0\n"                          \
 689                         "\tjmp     2b\n"                                \
 690                         "\t.previous\n"                                 \
 691                         _ASM_EXTABLE_UA(1b, 3b)                         \
 692                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 693                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 694                         : "memory"                                      \
 695                 );                                                      \
 696                 break;                                                  \
 697         }                                                               \
 698         case 2:                                                         \
 699         {                                                               \
 700                 asm volatile("\n"                                       \
 701                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 702                         "2:\n"                                          \
 703                         "\t.section .fixup, \"ax\"\n"                   \
 704                         "3:\tmov     %3, %0\n"                          \
 705                         "\tjmp     2b\n"                                \
 706                         "\t.previous\n"                                 \
 707                         _ASM_EXTABLE_UA(1b, 3b)                         \
 708                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 709                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 710                         : "memory"                                      \
 711                 );                                                      \
 712                 break;                                                  \
 713         }                                                               \
 714         case 4:                                                         \
 715         {                                                               \
 716                 asm volatile("\n"                                       \
 717                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 718                         "2:\n"                                          \
 719                         "\t.section .fixup, \"ax\"\n"                   \
 720                         "3:\tmov     %3, %0\n"                          \
 721                         "\tjmp     2b\n"                                \
 722                         "\t.previous\n"                                 \
 723                         _ASM_EXTABLE_UA(1b, 3b)                         \
 724                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 725                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 726                         : "memory"                                      \
 727                 );                                                      \
 728                 break;                                                  \
 729         }                                                               \
 730         case 8:                                                         \
 731         {                                                               \
 732                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 733                         __cmpxchg_wrong_size();                         \
 734                                                                         \
 735                 asm volatile("\n"                                       \
 736                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 737                         "2:\n"                                          \
 738                         "\t.section .fixup, \"ax\"\n"                   \
 739                         "3:\tmov     %3, %0\n"                          \
 740                         "\tjmp     2b\n"                                \
 741                         "\t.previous\n"                                 \
 742                         _ASM_EXTABLE_UA(1b, 3b)                         \
 743                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 744                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 745                         : "memory"                                      \
 746                 );                                                      \
 747                 break;                                                  \
 748         }                                                               \
 749         default:                                                        \
 750                 __cmpxchg_wrong_size();                                 \
 751         }                                                               \
 752         __uaccess_end();                                                \
 753         *(uval) = __old;                                                \
 754         __ret;                                                          \
 755 })
 756
 757 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 758 ({                                                                      \
 759         access_ok((ptr), sizeof(*(ptr))) ?              \
 760                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 761                                 (old), (new), sizeof(*(ptr))) :         \
 762                 -EFAULT;                                                \
 763 })
 764
 765 /*
 766  * movsl can be slow when source and dest are not both 8-byte aligned
 767  */
 768 #ifdef CONFIG_X86_INTEL_USERCOPY
 769 extern struct movsl_mask {
 770         int mask;
 771 } ____cacheline_aligned_in_smp movsl_mask;
 772 #endif
 773
 774 #define ARCH_HAS_NOCACHE_UACCESS 1
 775
 776 #ifdef CONFIG_X86_32
 777 # include <asm/uaccess_32.h>
 778 #else
 779 # include <asm/uaccess_64.h>
 780 #endif
 781
 782 /*
 783  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 784  * nested NMI paths are careful to preserve CR2.
 785  *
 786  * Caller must use pagefault_enable/disable, or run in interrupt context,
 787  * and also do a uaccess_ok() check
 788  */
 789 #define __copy_from_user_nmi __copy_from_user_inatomic
 790
 791 /*
 792  * The "unsafe" user accesses aren't really "unsafe", but the naming
 793  * is a big fat warning: you have to not only do the access_ok()
 794  * checking before using them, but you have to surround them with the
 795  * user_access_begin/end() pair.
 796  */
 797 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
 798 {
 799         if (unlikely(!access_ok(ptr,len)))
 800                 return 0;
 801         __uaccess_begin_nospec();
 802         return 1;
 803 }
 804 #define user_access_begin(a,b)  user_access_begin(a,b)
 805 #define user_access_end()       __uaccess_end()
 806
 807 #define user_access_save()      smap_save()
 808 #define user_access_restore(x)  smap_restore(x)
 809
 810 #define unsafe_put_user(x, ptr, label)  \
 811         __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
 812
 813 #define unsafe_get_user(x, ptr, err_label)                                      \
 814 do {                                                                            \
 815         int __gu_err;                                                           \
 816         __inttype(*(ptr)) __gu_val;                                             \
 817         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 818         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 819         if (unlikely(__gu_err)) goto err_label;                                 \
 820 } while (0)
 821
 822 extern void __try_cmpxchg_user_wrong_size(void);
 823
 824 #ifndef CONFIG_X86_32
 825 #define __try_cmpxchg64_user_asm(_ptr, _oldp, _nval, _label)            \
 826         __try_cmpxchg_user_asm("q", "r", (_ptr), (_oldp), (_nval), _label)
 827 #endif
 828
 829 /*
 830  * Force the pointer to u<size> to match the size expected by the asm helper.
 831  * clang/LLVM compiles all cases and only discards the unused paths after
 832  * processing errors, which breaks i386 if the pointer is an 8-byte value.
 833  */
 834 #define unsafe_try_cmpxchg_user(_ptr, _oldp, _nval, _label) ({                  \
 835         bool __ret;                                                             \
 836         __chk_user_ptr(_ptr);                                                   \
 837         switch (sizeof(*(_ptr))) {                                              \
 838         case 1: __ret = __try_cmpxchg_user_asm("b", "q",                        \
 839                                                (__force u8 *)(_ptr), (_oldp),   \
 840                                                (_nval), _label);                \
 841                 break;                                                          \
 842         case 2: __ret = __try_cmpxchg_user_asm("w", "r",                        \
 843                                                (__force u16 *)(_ptr), (_oldp),  \
 844                                                (_nval), _label);                \
 845                 break;                                                          \
 846         case 4: __ret = __try_cmpxchg_user_asm("l", "r",                        \
 847                                                (__force u32 *)(_ptr), (_oldp),  \
 848                                                (_nval), _label);                \
 849                 break;                                                          \
 850         case 8: __ret = __try_cmpxchg64_user_asm((__force u64 *)(_ptr), (_oldp),\
 851                                                  (_nval), _label);              \
 852                 break;                                                          \
 853         default: __try_cmpxchg_user_wrong_size();                               \
 854         }                                                                       \
 855         __ret;                                          })
 856
 857 /* "Returns" 0 on success, 1 on failure, -EFAULT if the access faults. */
 858 #define __try_cmpxchg_user(_ptr, _oldp, _nval, _label)  ({              \
 859         int __ret = -EFAULT;                                            \
 860         __uaccess_begin_nospec();                                       \
 861         __ret = !unsafe_try_cmpxchg_user(_ptr, _oldp, _nval, _label);   \
 862 _label:                                                                 \
 863         __uaccess_end();                                                \
 864         __ret;                                                          \
 865                                                         })
 866
 867 /*
 868  * We want the unsafe accessors to always be inlined and use
 869  * the error labels - thus the macro games.
 870  */
 871 #define unsafe_copy_loop(dst, src, len, type, label)                    \
 872         while (len >= sizeof(type)) {                                   \
 873                 unsafe_put_user(*(type *)src,(type __user *)dst,label); \
 874                 dst += sizeof(type);                                    \
 875                 src += sizeof(type);                                    \
 876                 len -= sizeof(type);                                    \
 877         }
 878
 879 #define unsafe_copy_to_user(_dst,_src,_len,label)                       \
 880 do {                                                                    \
 881         char __user *__ucu_dst = (_dst);                                \
 882         const char *__ucu_src = (_src);                                 \
 883         size_t __ucu_len = (_len);                                      \
 884         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label);  \
 885         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label);  \
 886         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label);  \
 887         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label);   \
 888 } while (0)
 889
 890 #endif /* _ASM_X86_UACCESS_H */
 891