1 #ifndef _ASM_X86_UACCESS_H
2 #define _ASM_X86_UACCESS_H
4 * User space memory access functions
6 #include <linux/errno.h>
7 #include <linux/compiler.h>
8 #include <linux/thread_info.h>
9 #include <linux/string.h>
15 #define VERIFY_WRITE 1
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.
22 * For historical reasons, these macros are grossly misnamed.
25 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
27 #define KERNEL_DS MAKE_MM_SEG(-1UL)
28 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
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))
34 #define segment_eq(a, b) ((a).seg == (b).seg)
36 #define user_addr_max() (current_thread_info()->addr_limit.seg)
37 #define __addr_ok(addr) \
38 ((unsigned long __force)(addr) < user_addr_max())
41 * Test whether a block of memory is a valid user space address.
42 * Returns 0 if the range is valid, nonzero otherwise.
44 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
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).
53 if (__builtin_constant_p(size))
54 return unlikely(addr > limit - size);
56 /* Arbitrary sizes? Be careful about overflow */
58 if (unlikely(addr < size))
60 return unlikely(addr > limit);
63 #define __range_not_ok(addr, size, limit) \
65 __chk_user_ptr(addr); \
66 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
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
77 * Context: User context only. This function may sleep if pagefaults are
80 * Checks if a pointer to a block of memory in user space is valid.
82 * Returns true (nonzero) if the memory block may be valid, false (zero)
83 * if it is definitely invalid.
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.
89 #define access_ok(type, addr, size) \
90 likely(!__range_not_ok(addr, size, user_addr_max()))
93 * The exception table consists of pairs of addresses relative to the
94 * exception table enty itself: the first is the address of an
95 * instruction that is allowed to fault, and the second is the address
96 * at which the program should continue. No registers are modified,
97 * so it is entirely up to the continuation code to figure out what to
100 * All the routines below use bits of fixup code that are out of line
101 * with the main instruction path. This means when everything is well,
102 * we don't even have to jump over them. Further, they do not intrude
103 * on our cache or tlb entries.
106 struct exception_table_entry {
109 /* This is not the generic standard exception_table_entry format */
110 #define ARCH_HAS_SORT_EXTABLE
111 #define ARCH_HAS_SEARCH_EXTABLE
113 extern int fixup_exception(struct pt_regs *regs);
114 extern int early_fixup_exception(unsigned long *ip);
117 * These are the main single-value transfer routines. They automatically
118 * use the right size if we just have the right pointer type.
120 * This gets kind of ugly. We want to return _two_ values in "get_user()"
121 * and yet we don't want to do any pointers, because that is too much
122 * of a performance impact. Thus we have a few rather ugly macros here,
123 * and hide all the ugliness from the user.
125 * The "__xxx" versions of the user access functions are versions that
126 * do not verify the address space, that must have been done previously
127 * with a separate "access_ok()" call (this is used when we do multiple
128 * accesses to the same area of user memory).
131 extern int __get_user_1(void);
132 extern int __get_user_2(void);
133 extern int __get_user_4(void);
134 extern int __get_user_8(void);
135 extern int __get_user_bad(void);
138 * This is a type: either unsigned long, if the argument fits into
139 * that type, or otherwise unsigned long long.
141 #define __inttype(x) \
142 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
145 * get_user: - Get a simple variable from user space.
146 * @x: Variable to store result.
147 * @ptr: Source address, in user space.
149 * Context: User context only. This function may sleep if pagefaults are
152 * This macro copies a single simple variable from user space to kernel
153 * space. It supports simple types like char and int, but not larger
154 * data types like structures or arrays.
156 * @ptr must have pointer-to-simple-variable type, and the result of
157 * dereferencing @ptr must be assignable to @x without a cast.
159 * Returns zero on success, or -EFAULT on error.
160 * On error, the variable @x is set to zero.
163 * Careful: we have to cast the result to the type of the pointer
166 * The use of _ASM_DX as the register specifier is a bit of a
167 * simplification, as gcc only cares about it as the starting point
168 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
169 * (%ecx being the next register in gcc's x86 register sequence), and
172 * Clang/LLVM cares about the size of the register, but still wants
173 * the base register for something that ends up being a pair.
175 #define get_user(x, ptr) \
178 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
179 __chk_user_ptr(ptr); \
181 asm volatile("call __get_user_%P3" \
182 : "=a" (__ret_gu), "=r" (__val_gu) \
183 : "0" (ptr), "i" (sizeof(*(ptr)))); \
184 (x) = (__force __typeof__(*(ptr))) __val_gu; \
185 __builtin_expect(__ret_gu, 0); \
188 #define __put_user_x(size, x, ptr, __ret_pu) \
189 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
190 : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
195 #define __put_user_asm_u64(x, addr, err, errret) \
196 asm volatile(ASM_STAC "\n" \
197 "1: movl %%eax,0(%2)\n" \
198 "2: movl %%edx,4(%2)\n" \
199 "3: " ASM_CLAC "\n" \
200 ".section .fixup,\"ax\"\n" \
204 _ASM_EXTABLE(1b, 4b) \
205 _ASM_EXTABLE(2b, 4b) \
207 : "A" (x), "r" (addr), "i" (errret), "0" (err))
209 #define __put_user_asm_ex_u64(x, addr) \
210 asm volatile(ASM_STAC "\n" \
211 "1: movl %%eax,0(%1)\n" \
212 "2: movl %%edx,4(%1)\n" \
213 "3: " ASM_CLAC "\n" \
214 _ASM_EXTABLE_EX(1b, 2b) \
215 _ASM_EXTABLE_EX(2b, 3b) \
216 : : "A" (x), "r" (addr))
218 #define __put_user_x8(x, ptr, __ret_pu) \
219 asm volatile("call __put_user_8" : "=a" (__ret_pu) \
220 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
222 #define __put_user_asm_u64(x, ptr, retval, errret) \
223 __put_user_asm(x, ptr, retval, "q", "", "er", errret)
224 #define __put_user_asm_ex_u64(x, addr) \
225 __put_user_asm_ex(x, addr, "q", "", "er")
226 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
229 extern void __put_user_bad(void);
232 * Strange magic calling convention: pointer in %ecx,
233 * value in %eax(:%edx), return value in %eax. clobbers %rbx
235 extern void __put_user_1(void);
236 extern void __put_user_2(void);
237 extern void __put_user_4(void);
238 extern void __put_user_8(void);
241 * put_user: - Write a simple value into user space.
242 * @x: Value to copy to user space.
243 * @ptr: Destination address, in user space.
245 * Context: User context only. This function may sleep if pagefaults are
248 * This macro copies a single simple value from kernel space to user
249 * space. It supports simple types like char and int, but not larger
250 * data types like structures or arrays.
252 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
253 * to the result of dereferencing @ptr.
255 * Returns zero on success, or -EFAULT on error.
257 #define put_user(x, ptr) \
260 __typeof__(*(ptr)) __pu_val; \
261 __chk_user_ptr(ptr); \
264 switch (sizeof(*(ptr))) { \
266 __put_user_x(1, __pu_val, ptr, __ret_pu); \
269 __put_user_x(2, __pu_val, ptr, __ret_pu); \
272 __put_user_x(4, __pu_val, ptr, __ret_pu); \
275 __put_user_x8(__pu_val, ptr, __ret_pu); \
278 __put_user_x(X, __pu_val, ptr, __ret_pu); \
281 __builtin_expect(__ret_pu, 0); \
284 #define __put_user_size(x, ptr, size, retval, errret) \
287 __chk_user_ptr(ptr); \
290 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
293 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
296 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
299 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \
307 #define __put_user_size_ex(x, ptr, size) \
309 __chk_user_ptr(ptr); \
312 __put_user_asm_ex(x, ptr, "b", "b", "iq"); \
315 __put_user_asm_ex(x, ptr, "w", "w", "ir"); \
318 __put_user_asm_ex(x, ptr, "l", "k", "ir"); \
321 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \
329 #define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad()
330 #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad()
332 #define __get_user_asm_u64(x, ptr, retval, errret) \
333 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
334 #define __get_user_asm_ex_u64(x, ptr) \
335 __get_user_asm_ex(x, ptr, "q", "", "=r")
338 #define __get_user_size(x, ptr, size, retval, errret) \
341 __chk_user_ptr(ptr); \
344 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
347 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
350 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
353 __get_user_asm_u64(x, ptr, retval, errret); \
356 (x) = __get_user_bad(); \
360 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
361 asm volatile(ASM_STAC "\n" \
362 "1: mov"itype" %2,%"rtype"1\n" \
363 "2: " ASM_CLAC "\n" \
364 ".section .fixup,\"ax\"\n" \
366 " xor"itype" %"rtype"1,%"rtype"1\n" \
369 _ASM_EXTABLE(1b, 3b) \
370 : "=r" (err), ltype(x) \
371 : "m" (__m(addr)), "i" (errret), "0" (err))
373 #define __get_user_size_ex(x, ptr, size) \
375 __chk_user_ptr(ptr); \
378 __get_user_asm_ex(x, ptr, "b", "b", "=q"); \
381 __get_user_asm_ex(x, ptr, "w", "w", "=r"); \
384 __get_user_asm_ex(x, ptr, "l", "k", "=r"); \
387 __get_user_asm_ex_u64(x, ptr); \
390 (x) = __get_user_bad(); \
394 #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \
395 asm volatile("1: mov"itype" %1,%"rtype"0\n" \
397 ".section .fixup,\"ax\"\n" \
398 "3:xor"itype" %"rtype"0,%"rtype"0\n" \
401 _ASM_EXTABLE_EX(1b, 3b) \
402 : ltype(x) : "m" (__m(addr)))
404 #define __put_user_nocheck(x, ptr, size) \
407 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
408 __builtin_expect(__pu_err, 0); \
411 #define __get_user_nocheck(x, ptr, size) \
414 unsigned long __gu_val; \
415 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
416 (x) = (__force __typeof__(*(ptr)))__gu_val; \
417 __builtin_expect(__gu_err, 0); \
420 /* FIXME: this hack is definitely wrong -AK */
421 struct __large_struct { unsigned long buf[100]; };
422 #define __m(x) (*(struct __large_struct __user *)(x))
425 * Tell gcc we read from memory instead of writing: this is because
426 * we do not write to any memory gcc knows about, so there are no
429 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
430 asm volatile(ASM_STAC "\n" \
431 "1: mov"itype" %"rtype"1,%2\n" \
432 "2: " ASM_CLAC "\n" \
433 ".section .fixup,\"ax\"\n" \
437 _ASM_EXTABLE(1b, 3b) \
439 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
441 #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \
442 asm volatile("1: mov"itype" %"rtype"0,%1\n" \
444 _ASM_EXTABLE_EX(1b, 2b) \
445 : : ltype(x), "m" (__m(addr)))
448 * uaccess_try and catch
450 #define uaccess_try do { \
451 current_thread_info()->uaccess_err = 0; \
455 #define uaccess_catch(err) \
457 (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \
461 * __get_user: - Get a simple variable from user space, with less checking.
462 * @x: Variable to store result.
463 * @ptr: Source address, in user space.
465 * Context: User context only. This function may sleep if pagefaults are
468 * This macro copies a single simple variable from user space to kernel
469 * space. It supports simple types like char and int, but not larger
470 * data types like structures or arrays.
472 * @ptr must have pointer-to-simple-variable type, and the result of
473 * dereferencing @ptr must be assignable to @x without a cast.
475 * Caller must check the pointer with access_ok() before calling this
478 * Returns zero on success, or -EFAULT on error.
479 * On error, the variable @x is set to zero.
482 #define __get_user(x, ptr) \
483 __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
486 * __put_user: - Write a simple value into user space, with less checking.
487 * @x: Value to copy to user space.
488 * @ptr: Destination address, in user space.
490 * Context: User context only. This function may sleep if pagefaults are
493 * This macro copies a single simple value from kernel space to user
494 * space. It supports simple types like char and int, but not larger
495 * data types like structures or arrays.
497 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
498 * to the result of dereferencing @ptr.
500 * Caller must check the pointer with access_ok() before calling this
503 * Returns zero on success, or -EFAULT on error.
506 #define __put_user(x, ptr) \
507 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
509 #define __get_user_unaligned __get_user
510 #define __put_user_unaligned __put_user
513 * {get|put}_user_try and catch
517 * } get_user_catch(err)
519 #define get_user_try uaccess_try
520 #define get_user_catch(err) uaccess_catch(err)
522 #define get_user_ex(x, ptr) do { \
523 unsigned long __gue_val; \
524 __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \
525 (x) = (__force __typeof__(*(ptr)))__gue_val; \
528 #define put_user_try uaccess_try
529 #define put_user_catch(err) uaccess_catch(err)
531 #define put_user_ex(x, ptr) \
532 __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
535 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
536 extern __must_check long
537 strncpy_from_user(char *dst, const char __user *src, long count);
539 extern __must_check long strlen_user(const char __user *str);
540 extern __must_check long strnlen_user(const char __user *str, long n);
542 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
543 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
545 extern void __cmpxchg_wrong_size(void)
546 __compiletime_error("Bad argument size for cmpxchg");
548 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \
551 __typeof__(ptr) __uval = (uval); \
552 __typeof__(*(ptr)) __old = (old); \
553 __typeof__(*(ptr)) __new = (new); \
557 asm volatile("\t" ASM_STAC "\n" \
558 "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \
559 "2:\t" ASM_CLAC "\n" \
560 "\t.section .fixup, \"ax\"\n" \
564 _ASM_EXTABLE(1b, 3b) \
565 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
566 : "i" (-EFAULT), "q" (__new), "1" (__old) \
573 asm volatile("\t" ASM_STAC "\n" \
574 "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \
575 "2:\t" ASM_CLAC "\n" \
576 "\t.section .fixup, \"ax\"\n" \
580 _ASM_EXTABLE(1b, 3b) \
581 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
582 : "i" (-EFAULT), "r" (__new), "1" (__old) \
589 asm volatile("\t" ASM_STAC "\n" \
590 "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \
591 "2:\t" ASM_CLAC "\n" \
592 "\t.section .fixup, \"ax\"\n" \
596 _ASM_EXTABLE(1b, 3b) \
597 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
598 : "i" (-EFAULT), "r" (__new), "1" (__old) \
605 if (!IS_ENABLED(CONFIG_X86_64)) \
606 __cmpxchg_wrong_size(); \
608 asm volatile("\t" ASM_STAC "\n" \
609 "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \
610 "2:\t" ASM_CLAC "\n" \
611 "\t.section .fixup, \"ax\"\n" \
615 _ASM_EXTABLE(1b, 3b) \
616 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
617 : "i" (-EFAULT), "r" (__new), "1" (__old) \
623 __cmpxchg_wrong_size(); \
629 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \
631 access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \
632 __user_atomic_cmpxchg_inatomic((uval), (ptr), \
633 (old), (new), sizeof(*(ptr))) : \
638 * movsl can be slow when source and dest are not both 8-byte aligned
640 #ifdef CONFIG_X86_INTEL_USERCOPY
641 extern struct movsl_mask {
643 } ____cacheline_aligned_in_smp movsl_mask;
646 #define ARCH_HAS_NOCACHE_UACCESS 1
649 # include <asm/uaccess_32.h>
651 # include <asm/uaccess_64.h>
654 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
656 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
659 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
660 # define copy_user_diag __compiletime_error
662 # define copy_user_diag __compiletime_warning
665 extern void copy_user_diag("copy_from_user() buffer size is too small")
666 copy_from_user_overflow(void);
667 extern void copy_user_diag("copy_to_user() buffer size is too small")
668 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
670 #undef copy_user_diag
672 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
675 __compiletime_warning("copy_from_user() buffer size is not provably correct")
676 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
677 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
680 __compiletime_warning("copy_to_user() buffer size is not provably correct")
681 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
682 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
687 __copy_from_user_overflow(int size, unsigned long count)
689 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
692 #define __copy_to_user_overflow __copy_from_user_overflow
696 static inline unsigned long __must_check
697 copy_from_user(void *to, const void __user *from, unsigned long n)
699 int sz = __compiletime_object_size(to);
704 * While we would like to have the compiler do the checking for us
705 * even in the non-constant size case, any false positives there are
706 * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
707 * without - the [hopefully] dangerous looking nature of the warning
708 * would make people go look at the respecitive call sites over and
709 * over again just to find that there's no problem).
711 * And there are cases where it's just not realistic for the compiler
712 * to prove the count to be in range. For example when multiple call
713 * sites of a helper function - perhaps in different source files -
714 * all doing proper range checking, yet the helper function not doing
717 * Therefore limit the compile time checking to the constant size
718 * case, and do only runtime checking for non-constant sizes.
721 if (likely(sz < 0 || sz >= n))
722 n = _copy_from_user(to, from, n);
723 else if(__builtin_constant_p(n))
724 copy_from_user_overflow();
726 __copy_from_user_overflow(sz, n);
731 static inline unsigned long __must_check
732 copy_to_user(void __user *to, const void *from, unsigned long n)
734 int sz = __compiletime_object_size(from);
738 /* See the comment in copy_from_user() above. */
739 if (likely(sz < 0 || sz >= n))
740 n = _copy_to_user(to, from, n);
741 else if(__builtin_constant_p(n))
742 copy_to_user_overflow();
744 __copy_to_user_overflow(sz, n);
749 #undef __copy_from_user_overflow
750 #undef __copy_to_user_overflow
752 #endif /* _ASM_X86_UACCESS_H */