| 1 | /* |
| 2 | * arch/ubicom32/include/asm/uaccess.c |
| 3 | * User space memory access functions for Ubicom32 architecture. |
| 4 | * |
| 5 | * (C) Copyright 2009, Ubicom, Inc. |
| 6 | * |
| 7 | * This file is part of the Ubicom32 Linux Kernel Port. |
| 8 | * |
| 9 | * The Ubicom32 Linux Kernel Port is free software: you can redistribute |
| 10 | * it and/or modify it under the terms of the GNU General Public License |
| 11 | * as published by the Free Software Foundation, either version 2 of the |
| 12 | * License, or (at your option) any later version. |
| 13 | * |
| 14 | * The Ubicom32 Linux Kernel Port is distributed in the hope that it |
| 15 | * will be useful, but WITHOUT ANY WARRANTY; without even the implied |
| 16 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See |
| 17 | * the GNU General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU General Public License |
| 20 | * along with the Ubicom32 Linux Kernel Port. If not, |
| 21 | * see <http://www.gnu.org/licenses/>. |
| 22 | * |
| 23 | * Ubicom32 implementation derived from (with many thanks): |
| 24 | * arch/m68knommu |
| 25 | * arch/blackfin |
| 26 | * arch/parisc |
| 27 | */ |
| 28 | |
| 29 | #include <linux/sched.h> |
| 30 | #include <linux/mm.h> |
| 31 | #include <linux/string.h> |
| 32 | #include <linux/module.h> |
| 33 | |
| 34 | #include <asm/segment.h> |
| 35 | #include <asm/uaccess.h> |
| 36 | |
| 37 | extern int _stext, _etext, _sdata, _edata, _sbss, _ebss, _end; |
| 38 | |
| 39 | /* |
| 40 | * __access_ok() |
| 41 | * Check that the address is in the current processes. |
| 42 | * |
| 43 | * NOTE: The kernel uses "pretend" user addresses that wind |
| 44 | * up calling access_ok() so this approach has only marginal |
| 45 | * value because you wind up with lots of false positives. |
| 46 | */ |
| 47 | int __access_ok(unsigned long addr, unsigned long size) |
| 48 | { |
| 49 | // struct vm_area_struct *vma; |
| 50 | |
| 51 | /* |
| 52 | * Don't do anything if we are not a running system yet. |
| 53 | */ |
| 54 | if (system_state != SYSTEM_RUNNING) { |
| 55 | return 1; |
| 56 | } |
| 57 | |
| 58 | /* |
| 59 | * It appears that Linux will call this function even when we are not |
| 60 | * in the context of a user space application that has a VM address |
| 61 | * space. So we must check that current and mm are valid before |
| 62 | * performing the check. |
| 63 | */ |
| 64 | if ((!current) || (!current->mm)) { |
| 65 | return 1; |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * We perform some basic checks on the address to ensure that it |
| 70 | * is at least within the range of DRAM. |
| 71 | */ |
| 72 | if ((addr < (int)&_etext) || (addr > memory_end)) { |
| 73 | printk(KERN_WARNING "pid=%d[%s]: range [%lx - %lx] not in memory area: [%lx - %lx]\n", |
| 74 | current->pid, current->comm, |
| 75 | addr, addr + size, |
| 76 | memory_start, memory_end); |
| 77 | return 0; |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * For nommu Linux we can check this by looking at the allowed |
| 82 | * memory map for the process. |
| 83 | * |
| 84 | * TODO: Since the kernel passes addresses in it's own space as though |
| 85 | * they were user address, we can not validate the addresses this way. |
| 86 | */ |
| 87 | #if 0 |
| 88 | if (!down_read_trylock(¤t->mm->mmap_sem)) { |
| 89 | return 1; |
| 90 | } |
| 91 | vma = find_vma(current->mm, addr); |
| 92 | if (!vma) { |
| 93 | up_read(¤t->mm->mmap_sem); |
| 94 | printk(KERN_WARNING "pid=%d[%s]: possible invalid acesss on range: [%lx - %lx]\n", |
| 95 | current->pid, current->comm, addr, addr + size); |
| 96 | return 1; |
| 97 | } |
| 98 | if ((addr + size) > vma->vm_end) { |
| 99 | up_read(¤t->mm->mmap_sem); |
| 100 | printk(KERN_WARNING "pid=%d[%s]: possible invalid length on range: [%lx - %lx]\n", |
| 101 | current->pid, current->comm, addr, addr + size); |
| 102 | return 1; |
| 103 | } |
| 104 | up_read(¤t->mm->mmap_sem); |
| 105 | #endif |
| 106 | return 1; |
| 107 | } |
| 108 | |
| 109 | EXPORT_SYMBOL(__access_ok); |
| 110 | |
