target/linux/ubicom32/files/arch/ubicom32/kernel/uaccess.c

   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(&current->mm->mmap_sem)) {
  89                 return 1;
  90         }
  91         vma = find_vma(current->mm, addr);
  92         if (!vma) {
  93                 up_read(&current->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(&current->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(&current->mm->mmap_sem);
 105 #endif
 106         return 1;
 107 }
 108
 109 EXPORT_SYMBOL(__access_ok);