1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * User memory access support for Hexagon
4 *
5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
6 */
7
8 #ifndef _ASM_UACCESS_H
9 #define _ASM_UACCESS_H
10 /*
11 * User space memory access functions
12 */
13 #include <linux/mm.h>
14 #include <asm/sections.h>
15
16 /*
17 * access_ok: - Checks if a user space pointer is valid
18 * @addr: User space pointer to start of block to check
19 * @size: Size of block to check
20 *
21 * Context: User context only. This function may sleep if pagefaults are
22 * enabled.
23 *
24 * Checks if a pointer to a block of memory in user space is valid.
25 *
26 * Returns true (nonzero) if the memory block *may* be valid, false (zero)
27 * if it is definitely invalid.
28 *
29 * User address space in Hexagon, like x86, goes to 0xbfffffff, so the
30 * simple MSB-based tests used by MIPS won't work. Some further
31 * optimization is probably possible here, but for now, keep it
32 * reasonably simple and not *too* slow. After all, we've got the
33 * MMU for backup.
34 */
35
36 #define __access_ok(addr, size) \
37 ((get_fs().seg == KERNEL_DS.seg) || \
38 (((unsigned long)addr < get_fs().seg) && \
39 (unsigned long)size < (get_fs().seg - (unsigned long)addr)))
40
41 /*
42 * When a kernel-mode page fault is taken, the faulting instruction
43 * address is checked against a table of exception_table_entries.
44 * Each entry is a tuple of the address of an instruction that may
45 * be authorized to fault, and the address at which execution should
46 * be resumed instead of the faulting instruction, so as to effect
47 * a workaround.
48 */
49
50 /* Assembly somewhat optimized copy routines */
51 unsigned long raw_copy_from_user(void *to, const void __user *from,
52 unsigned long n);
53 unsigned long raw_copy_to_user(void __user *to, const void *from,
54 unsigned long n);
55 #define INLINE_COPY_FROM_USER
56 #define INLINE_COPY_TO_USER
57
58 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
59 #define __clear_user(a, s) __clear_user_hexagon((a), (s))
60
61 #define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n)
62
63 /* get around the ifndef in asm-generic/uaccess.h */
64 #define __strnlen_user __strnlen_user
65
66 extern long __strnlen_user(const char __user *src, long n);
67
68 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
69 long n);
70
71 #include <asm-generic/uaccess.h>
72
73 /* Todo: an actual accelerated version of this. */
74 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
75 long n)
76 {
77 long res = __strnlen_user(src, n);
78
79 if (unlikely(!res))
80 return -EFAULT;
81
82 if (res > n) {
83 long left = raw_copy_from_user(dst, src, n);
84 if (unlikely(left))
85 memset(dst + (n - left), 0, left);
86 return n;
87 } else {
88 long left = raw_copy_from_user(dst, src, res);
89 if (unlikely(left))
90 memset(dst + (res - left), 0, left);
91 return res-1;
92 }
93 }
94
95 #endif