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/segment.h> 28 #include <asm/sections.h> 29 30 /* 31 * access_ok: - Checks if a user space pointer is valid 32 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that 33 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe 34 * to write to a block, it is always safe to read from it. 35 * @addr: User space pointer to start of block to check 36 * @size: Size of block to check 37 * 38 * Context: User context only. This function may sleep if pagefaults are 39 * enabled. 40 * 41 * Checks if a pointer to a block of memory in user space is valid. 42 * 43 * Returns true (nonzero) if the memory block *may* be valid, false (zero) 44 * if it is definitely invalid. 45 * 46 * User address space in Hexagon, like x86, goes to 0xbfffffff, so the 47 * simple MSB-based tests used by MIPS won't work. Some further 48 * optimization is probably possible here, but for now, keep it 49 * reasonably simple and not *too* slow. After all, we've got the 50 * MMU for backup. 51 */ 52 53 #define __access_ok(addr, size) \ 54 ((get_fs().seg == KERNEL_DS.seg) || \ 55 (((unsigned long)addr < get_fs().seg) && \ 56 (unsigned long)size < (get_fs().seg - (unsigned long)addr))) 57 58 /* 59 * When a kernel-mode page fault is taken, the faulting instruction 60 * address is checked against a table of exception_table_entries. 61 * Each entry is a tuple of the address of an instruction that may 62 * be authorized to fault, and the address at which execution should 63 * be resumed instead of the faulting instruction, so as to effect 64 * a workaround. 65 */ 66 67 /* Assembly somewhat optimized copy routines */ 68 unsigned long raw_copy_from_user(void *to, const void __user *from, 69 unsigned long n); 70 unsigned long raw_copy_to_user(void __user *to, const void *from, 71 unsigned long n); 72 #define INLINE_COPY_FROM_USER 73 #define INLINE_COPY_TO_USER 74 75 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count); 76 #define __clear_user(a, s) __clear_user_hexagon((a), (s)) 77 78 #define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n) 79 80 /* get around the ifndef in asm-generic/uaccess.h */ 81 #define __strnlen_user __strnlen_user 82 83 extern long __strnlen_user(const char __user *src, long n); 84 85 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src, 86 long n); 87 88 #include <asm-generic/uaccess.h> 89 90 /* Todo: an actual accelerated version of this. */ 91 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src, 92 long n) 93 { 94 long res = __strnlen_user(src, n); 95 96 if (unlikely(!res)) 97 return -EFAULT; 98 99 if (res > n) { 100 long left = raw_copy_from_user(dst, src, n); 101 if (unlikely(left)) 102 memset(dst + (n - left), 0, left); 103 return n; 104 } else { 105 long left = raw_copy_from_user(dst, src, res); 106 if (unlikely(left)) 107 memset(dst + (res - left), 0, left); 108 return res-1; 109 } 110 } 111 112 #endif 113