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/sched.h> 27 #include <linux/mm.h> 28 #include <asm/segment.h> 29 #include <asm/sections.h> 30 31 /* 32 * access_ok: - Checks if a user space pointer is valid 33 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that 34 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe 35 * to write to a block, it is always safe to read from it. 36 * @addr: User space pointer to start of block to check 37 * @size: Size of block to check 38 * 39 * Context: User context only. This function may sleep if pagefaults are 40 * enabled. 41 * 42 * Checks if a pointer to a block of memory in user space is valid. 43 * 44 * Returns true (nonzero) if the memory block *may* be valid, false (zero) 45 * if it is definitely invalid. 46 * 47 * User address space in Hexagon, like x86, goes to 0xbfffffff, so the 48 * simple MSB-based tests used by MIPS won't work. Some further 49 * optimization is probably possible here, but for now, keep it 50 * reasonably simple and not *too* slow. After all, we've got the 51 * MMU for backup. 52 */ 53 #define VERIFY_READ 0 54 #define VERIFY_WRITE 1 55 56 #define __access_ok(addr, size) \ 57 ((get_fs().seg == KERNEL_DS.seg) || \ 58 (((unsigned long)addr < get_fs().seg) && \ 59 (unsigned long)size < (get_fs().seg - (unsigned long)addr))) 60 61 /* 62 * When a kernel-mode page fault is taken, the faulting instruction 63 * address is checked against a table of exception_table_entries. 64 * Each entry is a tuple of the address of an instruction that may 65 * be authorized to fault, and the address at which execution should 66 * be resumed instead of the faulting instruction, so as to effect 67 * a workaround. 68 */ 69 70 /* Assembly somewhat optimized copy routines */ 71 unsigned long __copy_from_user_hexagon(void *to, const void __user *from, 72 unsigned long n); 73 unsigned long __copy_to_user_hexagon(void __user *to, const void *from, 74 unsigned long n); 75 76 #define __copy_from_user(to, from, n) __copy_from_user_hexagon(to, from, n) 77 #define __copy_to_user(to, from, n) __copy_to_user_hexagon(to, from, n) 78 79 /* 80 * XXX todo: some additonal performance gain is possible by 81 * implementing __copy_to/from_user_inatomic, which is much 82 * like __copy_to/from_user, but performs slightly less checking. 83 */ 84 85 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count); 86 #define __clear_user(a, s) __clear_user_hexagon((a), (s)) 87 88 #define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n) 89 90 /* get around the ifndef in asm-generic/uaccess.h */ 91 #define __strnlen_user __strnlen_user 92 93 extern long __strnlen_user(const char __user *src, long n); 94 95 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src, 96 long n); 97 98 #include <asm-generic/uaccess.h> 99 100 /* Todo: an actual accelerated version of this. */ 101 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src, 102 long n) 103 { 104 long res = __strnlen_user(src, n); 105 106 /* return from strnlen can't be zero -- that would be rubbish. */ 107 108 if (res > n) { 109 copy_from_user(dst, src, n); 110 return n; 111 } else { 112 copy_from_user(dst, src, res); 113 return res-1; 114 } 115 } 116 117 #endif 118