1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_UACCESS_H
3 #define _ASM_X86_UACCESS_H
5 * User space memory access functions
7 #include <linux/compiler.h>
8 #include <linux/kasan-checks.h>
9 #include <linux/string.h>
13 #include <asm/extable.h>
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.
20 * For historical reasons, these macros are grossly misnamed.
23 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
25 #define KERNEL_DS MAKE_MM_SEG(-1UL)
26 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
28 #define get_fs() (current->thread.addr_limit)
29 static inline void set_fs(mm_segment_t fs)
31 current->thread.addr_limit = fs;
32 /* On user-mode return, check fs is correct */
33 set_thread_flag(TIF_FSCHECK);
36 #define segment_eq(a, b) ((a).seg == (b).seg)
37 #define user_addr_max() (current->thread.addr_limit.seg)
40 * Test whether a block of memory is a valid user space address.
41 * Returns 0 if the range is valid, nonzero otherwise.
43 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
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).
52 if (__builtin_constant_p(size))
53 return unlikely(addr > limit - size);
55 /* Arbitrary sizes? Be careful about overflow */
57 if (unlikely(addr < size))
59 return unlikely(addr > limit);
62 #define __range_not_ok(addr, size, limit) \
64 __chk_user_ptr(addr); \
65 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
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())
73 # define WARN_ON_IN_IRQ()
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
81 * Context: User context only. This function may sleep if pagefaults are
84 * Checks if a pointer to a block of memory in user space is valid.
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.
90 * Return: true (nonzero) if the memory block may be valid, false (zero)
91 * if it is definitely invalid.
93 #define access_ok(addr, size) \
96 likely(!__range_not_ok(addr, size, user_addr_max())); \
100 * These are the main single-value transfer routines. They automatically
101 * use the right size if we just have the right pointer type.
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.
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).
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);
120 #define __uaccess_begin() stac()
121 #define __uaccess_end() clac()
122 #define __uaccess_begin_nospec() \
129 * This is a type: either unsigned long, if the argument fits into
130 * that type, or otherwise unsigned long long.
132 #define __inttype(x) \
133 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
136 * get_user - Get a simple variable from user space.
137 * @x: Variable to store result.
138 * @ptr: Source address, in user space.
140 * Context: User context only. This function may sleep if pagefaults are
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.
147 * @ptr must have pointer-to-simple-variable type, and the result of
148 * dereferencing @ptr must be assignable to @x without a cast.
150 * Return: zero on success, or -EFAULT on error.
151 * On error, the variable @x is set to zero.
154 * Careful: we have to cast the result to the type of the pointer
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
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.
166 #define get_user(x, ptr) \
169 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
170 __chk_user_ptr(ptr); \
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); \
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")
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) \
196 #define __put_user_x8(x, ptr, __ret_pu) \
197 asm volatile("call __put_user_8" : "=a" (__ret_pu) \
198 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
200 #define __put_user_goto_u64(x, ptr, label) \
201 __put_user_goto(x, ptr, "q", "", "er", label)
202 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
205 extern void __put_user_bad(void);
208 * Strange magic calling convention: pointer in %ecx,
209 * value in %eax(:%edx), return value in %eax. clobbers %rbx
211 extern void __put_user_1(void);
212 extern void __put_user_2(void);
213 extern void __put_user_4(void);
214 extern void __put_user_8(void);
217 * put_user - Write a simple value into user space.
218 * @x: Value to copy to user space.
219 * @ptr: Destination address, in user space.
221 * Context: User context only. This function may sleep if pagefaults are
224 * This macro copies a single simple value from kernel space to user
225 * space. It supports simple types like char and int, but not larger
226 * data types like structures or arrays.
228 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
229 * to the result of dereferencing @ptr.
231 * Return: zero on success, or -EFAULT on error.
233 #define put_user(x, ptr) \
236 __typeof__(*(ptr)) __pu_val; \
237 __chk_user_ptr(ptr); \
240 switch (sizeof(*(ptr))) { \
242 __put_user_x(1, __pu_val, ptr, __ret_pu); \
245 __put_user_x(2, __pu_val, ptr, __ret_pu); \
248 __put_user_x(4, __pu_val, ptr, __ret_pu); \
251 __put_user_x8(__pu_val, ptr, __ret_pu); \
254 __put_user_x(X, __pu_val, ptr, __ret_pu); \
257 __builtin_expect(__ret_pu, 0); \
260 #define __put_user_size(x, ptr, size, label) \
262 __chk_user_ptr(ptr); \
265 __put_user_goto(x, ptr, "b", "b", "iq", label); \
268 __put_user_goto(x, ptr, "w", "w", "ir", label); \
271 __put_user_goto(x, ptr, "l", "k", "ir", label); \
274 __put_user_goto_u64(x, ptr, label); \
282 #define __get_user_asm_u64(x, ptr, retval, errret) \
284 __typeof__(ptr) __ptr = (ptr); \
286 "1: movl %2,%%eax\n" \
287 "2: movl %3,%%edx\n" \
289 ".section .fixup,\"ax\"\n" \
291 " xorl %%eax,%%eax\n" \
292 " xorl %%edx,%%edx\n" \
295 _ASM_EXTABLE_UA(1b, 4b) \
296 _ASM_EXTABLE_UA(2b, 4b) \
297 : "=r" (retval), "=&A"(x) \
298 : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1), \
299 "i" (errret), "0" (retval)); \
303 #define __get_user_asm_u64(x, ptr, retval, errret) \
304 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
307 #define __get_user_size(x, ptr, size, retval, errret) \
310 __chk_user_ptr(ptr); \
313 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
316 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
319 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
322 __get_user_asm_u64(x, ptr, retval, errret); \
325 (x) = __get_user_bad(); \
329 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
331 "1: mov"itype" %2,%"rtype"1\n" \
333 ".section .fixup,\"ax\"\n" \
335 " xor"itype" %"rtype"1,%"rtype"1\n" \
338 _ASM_EXTABLE_UA(1b, 3b) \
339 : "=r" (err), ltype(x) \
340 : "m" (__m(addr)), "i" (errret), "0" (err))
342 #define __put_user_nocheck(x, ptr, size) \
344 __label__ __pu_label; \
345 int __pu_err = -EFAULT; \
346 __typeof__(*(ptr)) __pu_val = (x); \
347 __typeof__(ptr) __pu_ptr = (ptr); \
348 __typeof__(size) __pu_size = (size); \
350 __put_user_size(__pu_val, __pu_ptr, __pu_size, __pu_label); \
354 __builtin_expect(__pu_err, 0); \
357 #define __get_user_nocheck(x, ptr, size) \
360 __inttype(*(ptr)) __gu_val; \
361 __typeof__(ptr) __gu_ptr = (ptr); \
362 __typeof__(size) __gu_size = (size); \
363 __uaccess_begin_nospec(); \
364 __get_user_size(__gu_val, __gu_ptr, __gu_size, __gu_err, -EFAULT); \
366 (x) = (__force __typeof__(*(ptr)))__gu_val; \
367 __builtin_expect(__gu_err, 0); \
370 /* FIXME: this hack is definitely wrong -AK */
371 struct __large_struct { unsigned long buf[100]; };
372 #define __m(x) (*(struct __large_struct __user *)(x))
375 * Tell gcc we read from memory instead of writing: this is because
376 * we do not write to any memory gcc knows about, so there are no
379 #define __put_user_goto(x, addr, itype, rtype, ltype, label) \
380 asm_volatile_goto("\n" \
381 "1: mov"itype" %"rtype"0,%1\n" \
382 _ASM_EXTABLE_UA(1b, %l2) \
383 : : ltype(x), "m" (__m(addr)) \
387 * __get_user - Get a simple variable from user space, with less checking.
388 * @x: Variable to store result.
389 * @ptr: Source address, in user space.
391 * Context: User context only. This function may sleep if pagefaults are
394 * This macro copies a single simple variable from user space to kernel
395 * space. It supports simple types like char and int, but not larger
396 * data types like structures or arrays.
398 * @ptr must have pointer-to-simple-variable type, and the result of
399 * dereferencing @ptr must be assignable to @x without a cast.
401 * Caller must check the pointer with access_ok() before calling this
404 * Return: zero on success, or -EFAULT on error.
405 * On error, the variable @x is set to zero.
408 #define __get_user(x, ptr) \
409 __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
412 * __put_user - Write a simple value into user space, with less checking.
413 * @x: Value to copy to user space.
414 * @ptr: Destination address, in user space.
416 * Context: User context only. This function may sleep if pagefaults are
419 * This macro copies a single simple value from kernel space to user
420 * space. It supports simple types like char and int, but not larger
421 * data types like structures or arrays.
423 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
424 * to the result of dereferencing @ptr.
426 * Caller must check the pointer with access_ok() before calling this
429 * Return: zero on success, or -EFAULT on error.
432 #define __put_user(x, ptr) \
433 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
436 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
437 extern __must_check long
438 strncpy_from_user(char *dst, const char __user *src, long count);
440 extern __must_check long strnlen_user(const char __user *str, long n);
442 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
443 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
446 * movsl can be slow when source and dest are not both 8-byte aligned
448 #ifdef CONFIG_X86_INTEL_USERCOPY
449 extern struct movsl_mask {
451 } ____cacheline_aligned_in_smp movsl_mask;
454 #define ARCH_HAS_NOCACHE_UACCESS 1
457 # include <asm/uaccess_32.h>
459 # include <asm/uaccess_64.h>
463 * The "unsafe" user accesses aren't really "unsafe", but the naming
464 * is a big fat warning: you have to not only do the access_ok()
465 * checking before using them, but you have to surround them with the
466 * user_access_begin/end() pair.
468 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
470 if (unlikely(!access_ok(ptr,len)))
472 __uaccess_begin_nospec();
475 #define user_access_begin(a,b) user_access_begin(a,b)
476 #define user_access_end() __uaccess_end()
478 #define user_access_save() smap_save()
479 #define user_access_restore(x) smap_restore(x)
481 #define unsafe_put_user(x, ptr, label) \
482 __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
484 #define unsafe_get_user(x, ptr, err_label) \
487 __inttype(*(ptr)) __gu_val; \
488 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \
489 (x) = (__force __typeof__(*(ptr)))__gu_val; \
490 if (unlikely(__gu_err)) goto err_label; \
494 * We want the unsafe accessors to always be inlined and use
495 * the error labels - thus the macro games.
497 #define unsafe_copy_loop(dst, src, len, type, label) \
498 while (len >= sizeof(type)) { \
499 unsafe_put_user(*(type *)src,(type __user *)dst,label); \
500 dst += sizeof(type); \
501 src += sizeof(type); \
502 len -= sizeof(type); \
505 #define unsafe_copy_to_user(_dst,_src,_len,label) \
507 char __user *__ucu_dst = (_dst); \
508 const char *__ucu_src = (_src); \
509 size_t __ucu_len = (_len); \
510 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \
511 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \
512 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \
513 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \
516 #endif /* _ASM_X86_UACCESS_H */