1 /* 2 * User memory access support for Hexagon 3 * 4 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 and 8 * only version 2 as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 18 * 02110-1301, USA. 19 */ 20 21 #ifndef _ASM_UACCESS_H 22 #define _ASM_UACCESS_H 23 /* 24 * User space memory access functions 25 */ 26 #include <linux/mm.h> 27 #include <asm/sections.h> 28 29 /* 30 * access_ok: - Checks if a user space pointer is valid 31 * @addr: User space pointer to start of block to check 32 * @size: Size of block to check 33 * 34 * Context: User context only. This function may sleep if pagefaults are 35 * enabled. 36 * 37 * Checks if a pointer to a block of memory in user space is valid. 38 * 39 * Returns true (nonzero) if the memory block *may* be valid, false (zero) 40 * if it is definitely invalid. 41 * 42 * User address space in Hexagon, like x86, goes to 0xbfffffff, so the 43 * simple MSB-based tests used by MIPS won't work. Some further 44 * optimization is probably possible here, but for now, keep it 45 * reasonably simple and not *too* slow. After all, we've got the 46 * MMU for backup. 47 */ 48 49 #define __access_ok(addr, size) \ 50 ((get_fs().seg == KERNEL_DS.seg) || \ 51 (((unsigned long)addr < get_fs().seg) && \ 52 (unsigned long)size < (get_fs().seg - (unsigned long)addr))) 53 54 /* 55 * When a kernel-mode page fault is taken, the faulting instruction 56 * address is checked against a table of exception_table_entries. 57 * Each entry is a tuple of the address of an instruction that may 58 * be authorized to fault, and the address at which execution should 59 * be resumed instead of the faulting instruction, so as to effect 60 * a workaround. 61 */ 62 63 /* Assembly somewhat optimized copy routines */ 64 unsigned long raw_copy_from_user(void *to, const void __user *from, 65 unsigned long n); 66 unsigned long raw_copy_to_user(void __user *to, const void *from, 67 unsigned long n); 68 #define INLINE_COPY_FROM_USER 69 #define INLINE_COPY_TO_USER 70 71 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count); 72 #define __clear_user(a, s) __clear_user_hexagon((a), (s)) 73 74 #define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n) 75 76 /* get around the ifndef in asm-generic/uaccess.h */ 77 #define __strnlen_user __strnlen_user 78 79 extern long __strnlen_user(const char __user *src, long n); 80 81 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src, 82 long n); 83 84 #include <asm-generic/uaccess.h> 85 86 /* Todo: an actual accelerated version of this. */ 87 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src, 88 long n) 89 { 90 long res = __strnlen_user(src, n); 91 92 if (unlikely(!res)) 93 return -EFAULT; 94 95 if (res > n) { 96 long left = raw_copy_from_user(dst, src, n); 97 if (unlikely(left)) 98 memset(dst + (n - left), 0, left); 99 return n; 100 } else { 101 long left = raw_copy_from_user(dst, src, res); 102 if (unlikely(left)) 103 memset(dst + (res - left), 0, left); 104 return res-1; 105 } 106 } 107 108 #endif 109