1 #ifndef _ASM_X86_UACCESS_H 2 #define _ASM_X86_UACCESS_H 3 /* 4 * User space memory access functions 5 */ 6 #include <linux/errno.h> 7 #include <linux/compiler.h> 8 #include <linux/thread_info.h> 9 #include <linux/string.h> 10 #include <asm/asm.h> 11 #include <asm/page.h> 12 #include <asm/smap.h> 13 14 #define VERIFY_READ 0 15 #define VERIFY_WRITE 1 16 17 /* 18 * The fs value determines whether argument validity checking should be 19 * performed or not. If get_fs() == USER_DS, checking is performed, with 20 * get_fs() == KERNEL_DS, checking is bypassed. 21 * 22 * For historical reasons, these macros are grossly misnamed. 23 */ 24 25 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) 26 27 #define KERNEL_DS MAKE_MM_SEG(-1UL) 28 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX) 29 30 #define get_ds() (KERNEL_DS) 31 #define get_fs() (current_thread_info()->addr_limit) 32 #define set_fs(x) (current_thread_info()->addr_limit = (x)) 33 34 #define segment_eq(a, b) ((a).seg == (b).seg) 35 36 #define user_addr_max() (current_thread_info()->addr_limit.seg) 37 #define __addr_ok(addr) \ 38 ((unsigned long __force)(addr) < user_addr_max()) 39 40 /* 41 * Test whether a block of memory is a valid user space address. 42 * Returns 0 if the range is valid, nonzero otherwise. 43 */ 44 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit) 45 { 46 /* 47 * If we have used "sizeof()" for the size, 48 * we know it won't overflow the limit (but 49 * it might overflow the 'addr', so it's 50 * important to subtract the size from the 51 * limit, not add it to the address). 52 */ 53 if (__builtin_constant_p(size)) 54 return unlikely(addr > limit - size); 55 56 /* Arbitrary sizes? Be careful about overflow */ 57 addr += size; 58 if (unlikely(addr < size)) 59 return true; 60 return unlikely(addr > limit); 61 } 62 63 #define __range_not_ok(addr, size, limit) \ 64 ({ \ 65 __chk_user_ptr(addr); \ 66 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \ 67 }) 68 69 /** 70 * access_ok: - Checks if a user space pointer is valid 71 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that 72 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe 73 * to write to a block, it is always safe to read from it. 74 * @addr: User space pointer to start of block to check 75 * @size: Size of block to check 76 * 77 * Context: User context only. This function may sleep if pagefaults are 78 * enabled. 79 * 80 * Checks if a pointer to a block of memory in user space is valid. 81 * 82 * Returns true (nonzero) if the memory block may be valid, false (zero) 83 * if it is definitely invalid. 84 * 85 * Note that, depending on architecture, this function probably just 86 * checks that the pointer is in the user space range - after calling 87 * this function, memory access functions may still return -EFAULT. 88 */ 89 #define access_ok(type, addr, size) \ 90 likely(!__range_not_ok(addr, size, user_addr_max())) 91 92 /* 93 * The exception table consists of triples of addresses relative to the 94 * exception table entry itself. The first address is of an instruction 95 * that is allowed to fault, the second is the target at which the program 96 * should continue. The third is a handler function to deal with the fault 97 * caused by the instruction in the first field. 98 * 99 * All the routines below use bits of fixup code that are out of line 100 * with the main instruction path. This means when everything is well, 101 * we don't even have to jump over them. Further, they do not intrude 102 * on our cache or tlb entries. 103 */ 104 105 struct exception_table_entry { 106 int insn, fixup, handler; 107 }; 108 109 #define ARCH_HAS_RELATIVE_EXTABLE 110 111 #define swap_ex_entry_fixup(a, b, tmp, delta) \ 112 do { \ 113 (a)->fixup = (b)->fixup + (delta); \ 114 (b)->fixup = (tmp).fixup - (delta); \ 115 (a)->handler = (b)->handler + (delta); \ 116 (b)->handler = (tmp).handler - (delta); \ 117 } while (0) 118 119 extern int fixup_exception(struct pt_regs *regs, int trapnr); 120 extern bool ex_has_fault_handler(unsigned long ip); 121 extern void early_fixup_exception(struct pt_regs *regs, int trapnr); 122 123 /* 124 * These are the main single-value transfer routines. They automatically 125 * use the right size if we just have the right pointer type. 126 * 127 * This gets kind of ugly. We want to return _two_ values in "get_user()" 128 * and yet we don't want to do any pointers, because that is too much 129 * of a performance impact. Thus we have a few rather ugly macros here, 130 * and hide all the ugliness from the user. 131 * 132 * The "__xxx" versions of the user access functions are versions that 133 * do not verify the address space, that must have been done previously 134 * with a separate "access_ok()" call (this is used when we do multiple 135 * accesses to the same area of user memory). 136 */ 137 138 extern int __get_user_1(void); 139 extern int __get_user_2(void); 140 extern int __get_user_4(void); 141 extern int __get_user_8(void); 142 extern int __get_user_bad(void); 143 144 #define __uaccess_begin() stac() 145 #define __uaccess_end() clac() 146 147 /* 148 * This is a type: either unsigned long, if the argument fits into 149 * that type, or otherwise unsigned long long. 150 */ 151 #define __inttype(x) \ 152 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 153 154 /** 155 * get_user: - Get a simple variable from user space. 156 * @x: Variable to store result. 157 * @ptr: Source address, in user space. 158 * 159 * Context: User context only. This function may sleep if pagefaults are 160 * enabled. 161 * 162 * This macro copies a single simple variable from user space to kernel 163 * space. It supports simple types like char and int, but not larger 164 * data types like structures or arrays. 165 * 166 * @ptr must have pointer-to-simple-variable type, and the result of 167 * dereferencing @ptr must be assignable to @x without a cast. 168 * 169 * Returns zero on success, or -EFAULT on error. 170 * On error, the variable @x is set to zero. 171 */ 172 /* 173 * Careful: we have to cast the result to the type of the pointer 174 * for sign reasons. 175 * 176 * The use of _ASM_DX as the register specifier is a bit of a 177 * simplification, as gcc only cares about it as the starting point 178 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits 179 * (%ecx being the next register in gcc's x86 register sequence), and 180 * %rdx on 64 bits. 181 * 182 * Clang/LLVM cares about the size of the register, but still wants 183 * the base register for something that ends up being a pair. 184 */ 185 #define get_user(x, ptr) \ 186 ({ \ 187 int __ret_gu; \ 188 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ 189 register void *__sp asm(_ASM_SP); \ 190 __chk_user_ptr(ptr); \ 191 might_fault(); \ 192 asm volatile("call __get_user_%P4" \ 193 : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp) \ 194 : "0" (ptr), "i" (sizeof(*(ptr)))); \ 195 (x) = (__force __typeof__(*(ptr))) __val_gu; \ 196 __builtin_expect(__ret_gu, 0); \ 197 }) 198 199 #define __put_user_x(size, x, ptr, __ret_pu) \ 200 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \ 201 : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") 202 203 204 205 #ifdef CONFIG_X86_32 206 #define __put_user_asm_u64(x, addr, err, errret) \ 207 asm volatile("\n" \ 208 "1: movl %%eax,0(%2)\n" \ 209 "2: movl %%edx,4(%2)\n" \ 210 "3:" \ 211 ".section .fixup,\"ax\"\n" \ 212 "4: movl %3,%0\n" \ 213 " jmp 3b\n" \ 214 ".previous\n" \ 215 _ASM_EXTABLE(1b, 4b) \ 216 _ASM_EXTABLE(2b, 4b) \ 217 : "=r" (err) \ 218 : "A" (x), "r" (addr), "i" (errret), "0" (err)) 219 220 #define __put_user_asm_ex_u64(x, addr) \ 221 asm volatile("\n" \ 222 "1: movl %%eax,0(%1)\n" \ 223 "2: movl %%edx,4(%1)\n" \ 224 "3:" \ 225 _ASM_EXTABLE_EX(1b, 2b) \ 226 _ASM_EXTABLE_EX(2b, 3b) \ 227 : : "A" (x), "r" (addr)) 228 229 #define __put_user_x8(x, ptr, __ret_pu) \ 230 asm volatile("call __put_user_8" : "=a" (__ret_pu) \ 231 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") 232 #else 233 #define __put_user_asm_u64(x, ptr, retval, errret) \ 234 __put_user_asm(x, ptr, retval, "q", "", "er", errret) 235 #define __put_user_asm_ex_u64(x, addr) \ 236 __put_user_asm_ex(x, addr, "q", "", "er") 237 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu) 238 #endif 239 240 extern void __put_user_bad(void); 241 242 /* 243 * Strange magic calling convention: pointer in %ecx, 244 * value in %eax(:%edx), return value in %eax. clobbers %rbx 245 */ 246 extern void __put_user_1(void); 247 extern void __put_user_2(void); 248 extern void __put_user_4(void); 249 extern void __put_user_8(void); 250 251 /** 252 * put_user: - Write a simple value into user space. 253 * @x: Value to copy to user space. 254 * @ptr: Destination address, in user space. 255 * 256 * Context: User context only. This function may sleep if pagefaults are 257 * enabled. 258 * 259 * This macro copies a single simple value from kernel space to user 260 * space. It supports simple types like char and int, but not larger 261 * data types like structures or arrays. 262 * 263 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 264 * to the result of dereferencing @ptr. 265 * 266 * Returns zero on success, or -EFAULT on error. 267 */ 268 #define put_user(x, ptr) \ 269 ({ \ 270 int __ret_pu; \ 271 __typeof__(*(ptr)) __pu_val; \ 272 __chk_user_ptr(ptr); \ 273 might_fault(); \ 274 __pu_val = x; \ 275 switch (sizeof(*(ptr))) { \ 276 case 1: \ 277 __put_user_x(1, __pu_val, ptr, __ret_pu); \ 278 break; \ 279 case 2: \ 280 __put_user_x(2, __pu_val, ptr, __ret_pu); \ 281 break; \ 282 case 4: \ 283 __put_user_x(4, __pu_val, ptr, __ret_pu); \ 284 break; \ 285 case 8: \ 286 __put_user_x8(__pu_val, ptr, __ret_pu); \ 287 break; \ 288 default: \ 289 __put_user_x(X, __pu_val, ptr, __ret_pu); \ 290 break; \ 291 } \ 292 __builtin_expect(__ret_pu, 0); \ 293 }) 294 295 #define __put_user_size(x, ptr, size, retval, errret) \ 296 do { \ 297 retval = 0; \ 298 __chk_user_ptr(ptr); \ 299 switch (size) { \ 300 case 1: \ 301 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \ 302 break; \ 303 case 2: \ 304 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \ 305 break; \ 306 case 4: \ 307 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \ 308 break; \ 309 case 8: \ 310 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \ 311 errret); \ 312 break; \ 313 default: \ 314 __put_user_bad(); \ 315 } \ 316 } while (0) 317 318 /* 319 * This doesn't do __uaccess_begin/end - the exception handling 320 * around it must do that. 321 */ 322 #define __put_user_size_ex(x, ptr, size) \ 323 do { \ 324 __chk_user_ptr(ptr); \ 325 switch (size) { \ 326 case 1: \ 327 __put_user_asm_ex(x, ptr, "b", "b", "iq"); \ 328 break; \ 329 case 2: \ 330 __put_user_asm_ex(x, ptr, "w", "w", "ir"); \ 331 break; \ 332 case 4: \ 333 __put_user_asm_ex(x, ptr, "l", "k", "ir"); \ 334 break; \ 335 case 8: \ 336 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \ 337 break; \ 338 default: \ 339 __put_user_bad(); \ 340 } \ 341 } while (0) 342 343 #ifdef CONFIG_X86_32 344 #define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad() 345 #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad() 346 #else 347 #define __get_user_asm_u64(x, ptr, retval, errret) \ 348 __get_user_asm(x, ptr, retval, "q", "", "=r", errret) 349 #define __get_user_asm_ex_u64(x, ptr) \ 350 __get_user_asm_ex(x, ptr, "q", "", "=r") 351 #endif 352 353 #define __get_user_size(x, ptr, size, retval, errret) \ 354 do { \ 355 retval = 0; \ 356 __chk_user_ptr(ptr); \ 357 switch (size) { \ 358 case 1: \ 359 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \ 360 break; \ 361 case 2: \ 362 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \ 363 break; \ 364 case 4: \ 365 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \ 366 break; \ 367 case 8: \ 368 __get_user_asm_u64(x, ptr, retval, errret); \ 369 break; \ 370 default: \ 371 (x) = __get_user_bad(); \ 372 } \ 373 } while (0) 374 375 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \ 376 asm volatile("\n" \ 377 "1: mov"itype" %2,%"rtype"1\n" \ 378 "2:\n" \ 379 ".section .fixup,\"ax\"\n" \ 380 "3: mov %3,%0\n" \ 381 " xor"itype" %"rtype"1,%"rtype"1\n" \ 382 " jmp 2b\n" \ 383 ".previous\n" \ 384 _ASM_EXTABLE(1b, 3b) \ 385 : "=r" (err), ltype(x) \ 386 : "m" (__m(addr)), "i" (errret), "0" (err)) 387 388 /* 389 * This doesn't do __uaccess_begin/end - the exception handling 390 * around it must do that. 391 */ 392 #define __get_user_size_ex(x, ptr, size) \ 393 do { \ 394 __chk_user_ptr(ptr); \ 395 switch (size) { \ 396 case 1: \ 397 __get_user_asm_ex(x, ptr, "b", "b", "=q"); \ 398 break; \ 399 case 2: \ 400 __get_user_asm_ex(x, ptr, "w", "w", "=r"); \ 401 break; \ 402 case 4: \ 403 __get_user_asm_ex(x, ptr, "l", "k", "=r"); \ 404 break; \ 405 case 8: \ 406 __get_user_asm_ex_u64(x, ptr); \ 407 break; \ 408 default: \ 409 (x) = __get_user_bad(); \ 410 } \ 411 } while (0) 412 413 #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \ 414 asm volatile("1: mov"itype" %1,%"rtype"0\n" \ 415 "2:\n" \ 416 _ASM_EXTABLE_EX(1b, 2b) \ 417 : ltype(x) : "m" (__m(addr))) 418 419 #define __put_user_nocheck(x, ptr, size) \ 420 ({ \ 421 int __pu_err; \ 422 __uaccess_begin(); \ 423 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \ 424 __uaccess_end(); \ 425 __builtin_expect(__pu_err, 0); \ 426 }) 427 428 #define __get_user_nocheck(x, ptr, size) \ 429 ({ \ 430 int __gu_err; \ 431 unsigned long __gu_val; \ 432 __uaccess_begin(); \ 433 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ 434 __uaccess_end(); \ 435 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 436 __builtin_expect(__gu_err, 0); \ 437 }) 438 439 /* FIXME: this hack is definitely wrong -AK */ 440 struct __large_struct { unsigned long buf[100]; }; 441 #define __m(x) (*(struct __large_struct __user *)(x)) 442 443 /* 444 * Tell gcc we read from memory instead of writing: this is because 445 * we do not write to any memory gcc knows about, so there are no 446 * aliasing issues. 447 */ 448 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \ 449 asm volatile("\n" \ 450 "1: mov"itype" %"rtype"1,%2\n" \ 451 "2:\n" \ 452 ".section .fixup,\"ax\"\n" \ 453 "3: mov %3,%0\n" \ 454 " jmp 2b\n" \ 455 ".previous\n" \ 456 _ASM_EXTABLE(1b, 3b) \ 457 : "=r"(err) \ 458 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err)) 459 460 #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \ 461 asm volatile("1: mov"itype" %"rtype"0,%1\n" \ 462 "2:\n" \ 463 _ASM_EXTABLE_EX(1b, 2b) \ 464 : : ltype(x), "m" (__m(addr))) 465 466 /* 467 * uaccess_try and catch 468 */ 469 #define uaccess_try do { \ 470 current_thread_info()->uaccess_err = 0; \ 471 __uaccess_begin(); \ 472 barrier(); 473 474 #define uaccess_catch(err) \ 475 __uaccess_end(); \ 476 (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \ 477 } while (0) 478 479 /** 480 * __get_user: - Get a simple variable from user space, with less checking. 481 * @x: Variable to store result. 482 * @ptr: Source address, in user space. 483 * 484 * Context: User context only. This function may sleep if pagefaults are 485 * enabled. 486 * 487 * This macro copies a single simple variable from user space to kernel 488 * space. It supports simple types like char and int, but not larger 489 * data types like structures or arrays. 490 * 491 * @ptr must have pointer-to-simple-variable type, and the result of 492 * dereferencing @ptr must be assignable to @x without a cast. 493 * 494 * Caller must check the pointer with access_ok() before calling this 495 * function. 496 * 497 * Returns zero on success, or -EFAULT on error. 498 * On error, the variable @x is set to zero. 499 */ 500 501 #define __get_user(x, ptr) \ 502 __get_user_nocheck((x), (ptr), sizeof(*(ptr))) 503 504 /** 505 * __put_user: - Write a simple value into user space, with less checking. 506 * @x: Value to copy to user space. 507 * @ptr: Destination address, in user space. 508 * 509 * Context: User context only. This function may sleep if pagefaults are 510 * enabled. 511 * 512 * This macro copies a single simple value from kernel space to user 513 * space. It supports simple types like char and int, but not larger 514 * data types like structures or arrays. 515 * 516 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 517 * to the result of dereferencing @ptr. 518 * 519 * Caller must check the pointer with access_ok() before calling this 520 * function. 521 * 522 * Returns zero on success, or -EFAULT on error. 523 */ 524 525 #define __put_user(x, ptr) \ 526 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) 527 528 #define __get_user_unaligned __get_user 529 #define __put_user_unaligned __put_user 530 531 /* 532 * {get|put}_user_try and catch 533 * 534 * get_user_try { 535 * get_user_ex(...); 536 * } get_user_catch(err) 537 */ 538 #define get_user_try uaccess_try 539 #define get_user_catch(err) uaccess_catch(err) 540 541 #define get_user_ex(x, ptr) do { \ 542 unsigned long __gue_val; \ 543 __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \ 544 (x) = (__force __typeof__(*(ptr)))__gue_val; \ 545 } while (0) 546 547 #define put_user_try uaccess_try 548 #define put_user_catch(err) uaccess_catch(err) 549 550 #define put_user_ex(x, ptr) \ 551 __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) 552 553 extern unsigned long 554 copy_from_user_nmi(void *to, const void __user *from, unsigned long n); 555 extern __must_check long 556 strncpy_from_user(char *dst, const char __user *src, long count); 557 558 extern __must_check long strlen_user(const char __user *str); 559 extern __must_check long strnlen_user(const char __user *str, long n); 560 561 unsigned long __must_check clear_user(void __user *mem, unsigned long len); 562 unsigned long __must_check __clear_user(void __user *mem, unsigned long len); 563 564 extern void __cmpxchg_wrong_size(void) 565 __compiletime_error("Bad argument size for cmpxchg"); 566 567 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \ 568 ({ \ 569 int __ret = 0; \ 570 __typeof__(ptr) __uval = (uval); \ 571 __typeof__(*(ptr)) __old = (old); \ 572 __typeof__(*(ptr)) __new = (new); \ 573 __uaccess_begin(); \ 574 switch (size) { \ 575 case 1: \ 576 { \ 577 asm volatile("\n" \ 578 "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \ 579 "2:\n" \ 580 "\t.section .fixup, \"ax\"\n" \ 581 "3:\tmov %3, %0\n" \ 582 "\tjmp 2b\n" \ 583 "\t.previous\n" \ 584 _ASM_EXTABLE(1b, 3b) \ 585 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 586 : "i" (-EFAULT), "q" (__new), "1" (__old) \ 587 : "memory" \ 588 ); \ 589 break; \ 590 } \ 591 case 2: \ 592 { \ 593 asm volatile("\n" \ 594 "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \ 595 "2:\n" \ 596 "\t.section .fixup, \"ax\"\n" \ 597 "3:\tmov %3, %0\n" \ 598 "\tjmp 2b\n" \ 599 "\t.previous\n" \ 600 _ASM_EXTABLE(1b, 3b) \ 601 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 602 : "i" (-EFAULT), "r" (__new), "1" (__old) \ 603 : "memory" \ 604 ); \ 605 break; \ 606 } \ 607 case 4: \ 608 { \ 609 asm volatile("\n" \ 610 "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \ 611 "2:\n" \ 612 "\t.section .fixup, \"ax\"\n" \ 613 "3:\tmov %3, %0\n" \ 614 "\tjmp 2b\n" \ 615 "\t.previous\n" \ 616 _ASM_EXTABLE(1b, 3b) \ 617 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 618 : "i" (-EFAULT), "r" (__new), "1" (__old) \ 619 : "memory" \ 620 ); \ 621 break; \ 622 } \ 623 case 8: \ 624 { \ 625 if (!IS_ENABLED(CONFIG_X86_64)) \ 626 __cmpxchg_wrong_size(); \ 627 \ 628 asm volatile("\n" \ 629 "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \ 630 "2:\n" \ 631 "\t.section .fixup, \"ax\"\n" \ 632 "3:\tmov %3, %0\n" \ 633 "\tjmp 2b\n" \ 634 "\t.previous\n" \ 635 _ASM_EXTABLE(1b, 3b) \ 636 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 637 : "i" (-EFAULT), "r" (__new), "1" (__old) \ 638 : "memory" \ 639 ); \ 640 break; \ 641 } \ 642 default: \ 643 __cmpxchg_wrong_size(); \ 644 } \ 645 __uaccess_end(); \ 646 *__uval = __old; \ 647 __ret; \ 648 }) 649 650 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \ 651 ({ \ 652 access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \ 653 __user_atomic_cmpxchg_inatomic((uval), (ptr), \ 654 (old), (new), sizeof(*(ptr))) : \ 655 -EFAULT; \ 656 }) 657 658 /* 659 * movsl can be slow when source and dest are not both 8-byte aligned 660 */ 661 #ifdef CONFIG_X86_INTEL_USERCOPY 662 extern struct movsl_mask { 663 int mask; 664 } ____cacheline_aligned_in_smp movsl_mask; 665 #endif 666 667 #define ARCH_HAS_NOCACHE_UACCESS 1 668 669 #ifdef CONFIG_X86_32 670 # include <asm/uaccess_32.h> 671 #else 672 # include <asm/uaccess_64.h> 673 #endif 674 675 unsigned long __must_check _copy_from_user(void *to, const void __user *from, 676 unsigned n); 677 unsigned long __must_check _copy_to_user(void __user *to, const void *from, 678 unsigned n); 679 680 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS 681 # define copy_user_diag __compiletime_error 682 #else 683 # define copy_user_diag __compiletime_warning 684 #endif 685 686 extern void copy_user_diag("copy_from_user() buffer size is too small") 687 copy_from_user_overflow(void); 688 extern void copy_user_diag("copy_to_user() buffer size is too small") 689 copy_to_user_overflow(void) __asm__("copy_from_user_overflow"); 690 691 #undef copy_user_diag 692 693 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS 694 695 extern void 696 __compiletime_warning("copy_from_user() buffer size is not provably correct") 697 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow"); 698 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow() 699 700 extern void 701 __compiletime_warning("copy_to_user() buffer size is not provably correct") 702 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow"); 703 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow() 704 705 #else 706 707 static inline void 708 __copy_from_user_overflow(int size, unsigned long count) 709 { 710 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); 711 } 712 713 #define __copy_to_user_overflow __copy_from_user_overflow 714 715 #endif 716 717 static inline unsigned long __must_check 718 copy_from_user(void *to, const void __user *from, unsigned long n) 719 { 720 int sz = __compiletime_object_size(to); 721 722 might_fault(); 723 724 /* 725 * While we would like to have the compiler do the checking for us 726 * even in the non-constant size case, any false positives there are 727 * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even 728 * without - the [hopefully] dangerous looking nature of the warning 729 * would make people go look at the respecitive call sites over and 730 * over again just to find that there's no problem). 731 * 732 * And there are cases where it's just not realistic for the compiler 733 * to prove the count to be in range. For example when multiple call 734 * sites of a helper function - perhaps in different source files - 735 * all doing proper range checking, yet the helper function not doing 736 * so again. 737 * 738 * Therefore limit the compile time checking to the constant size 739 * case, and do only runtime checking for non-constant sizes. 740 */ 741 742 if (likely(sz < 0 || sz >= n)) 743 n = _copy_from_user(to, from, n); 744 else if(__builtin_constant_p(n)) 745 copy_from_user_overflow(); 746 else 747 __copy_from_user_overflow(sz, n); 748 749 return n; 750 } 751 752 static inline unsigned long __must_check 753 copy_to_user(void __user *to, const void *from, unsigned long n) 754 { 755 int sz = __compiletime_object_size(from); 756 757 might_fault(); 758 759 /* See the comment in copy_from_user() above. */ 760 if (likely(sz < 0 || sz >= n)) 761 n = _copy_to_user(to, from, n); 762 else if(__builtin_constant_p(n)) 763 copy_to_user_overflow(); 764 else 765 __copy_to_user_overflow(sz, n); 766 767 return n; 768 } 769 770 #undef __copy_from_user_overflow 771 #undef __copy_to_user_overflow 772 773 /* 774 * We rely on the nested NMI work to allow atomic faults from the NMI path; the 775 * nested NMI paths are careful to preserve CR2. 776 * 777 * Caller must use pagefault_enable/disable, or run in interrupt context, 778 * and also do a uaccess_ok() check 779 */ 780 #define __copy_from_user_nmi __copy_from_user_inatomic 781 782 /* 783 * The "unsafe" user accesses aren't really "unsafe", but the naming 784 * is a big fat warning: you have to not only do the access_ok() 785 * checking before using them, but you have to surround them with the 786 * user_access_begin/end() pair. 787 */ 788 #define user_access_begin() __uaccess_begin() 789 #define user_access_end() __uaccess_end() 790 791 #define unsafe_put_user(x, ptr) \ 792 ({ \ 793 int __pu_err; \ 794 __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT); \ 795 __builtin_expect(__pu_err, 0); \ 796 }) 797 798 #define unsafe_get_user(x, ptr) \ 799 ({ \ 800 int __gu_err; \ 801 unsigned long __gu_val; \ 802 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \ 803 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 804 __builtin_expect(__gu_err, 0); \ 805 }) 806 807 #endif /* _ASM_X86_UACCESS_H */ 808 809