arch/sparc64/lib/user_fixup.c

   1 /* user_fixup.c: Fix up user copy faults.
   2  *
   3  * Copyright (C) 2004 David S. Miller <davem@redhat.com>
   4  */
   5
   6 #include <linux/compiler.h>
   7 #include <linux/kernel.h>
   8 #include <linux/string.h>
   9 #include <linux/errno.h>
  10 #include <asm/uaccess.h>
  11
  12 /* Calculating the exact fault address when using
  13  * block loads and stores can be very complicated.
  14  *
  15  * Instead of trying to be clever and handling all
  16  * of the cases, just fix things up simply here.
  17  */
  18
  19 static unsigned long compute_size(unsigned long start, unsigned long size, unsigned long *offset)
  20 {
  21         unsigned long fault_addr = current_thread_info()->fault_address;
  22         unsigned long end = start + size;
  23
  24         if (fault_addr < start || fault_addr >= end) {
  25                 *offset = 0;
  26         } else {
  27                 *offset = start - fault_addr;
  28                 size = end - fault_addr;
  29         }
  30         return size;
  31 }
  32
  33 unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)
  34 {
  35         unsigned long offset;
  36
  37         size = compute_size((unsigned long) from, size, &offset);
  38         if (likely(size))
  39                 memset(to + offset, 0, size);
  40
  41         return size;
  42 }
  43
  44 unsigned long copy_to_user_fixup(void __user *to, const void *from, unsigned long size)
  45 {
  46         unsigned long offset;
  47
  48         return compute_size((unsigned long) to, size, &offset);
  49 }
  50
  51 unsigned long copy_in_user_fixup(void __user *to, void __user *from, unsigned long size)
  52 {
  53         unsigned long fault_addr = current_thread_info()->fault_address;
  54         unsigned long start = (unsigned long) to;
  55         unsigned long end = start + size;
  56
  57         if (fault_addr >= start && fault_addr < end)
  58                 return end - fault_addr;
  59
  60         start = (unsigned long) from;
  61         end = start + size;
  62         if (fault_addr >= start && fault_addr < end)
  63                 return end - fault_addr;
  64
  65         return size;
  66 }