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/* user_fixup.c: Fix up user copy faults.
*
* Copyright (C) 2004 David S. Miller <davem@redhat.com>
*/
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <asm/uaccess.h>
/* Calculating the exact fault address when using
* block loads and stores can be very complicated.
*
* Instead of trying to be clever and handling all
* of the cases, just fix things up simply here.
*/
static unsigned long compute_size(unsigned long start, unsigned long size, unsigned long *offset)
{
unsigned long fault_addr = current_thread_info()->fault_address;
unsigned long end = start + size;
if (fault_addr < start || fault_addr >= end) {
*offset = 0;
} else {
*offset = start - fault_addr;
size = end - fault_addr;
}
return size;
}
unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)
{
unsigned long offset;
size = compute_size((unsigned long) from, size, &offset);
if (likely(size))
memset(to + offset, 0, size);
return size;
}
unsigned long copy_to_user_fixup(void __user *to, const void *from, unsigned long size)
{
unsigned long offset;
return compute_size((unsigned long) to, size, &offset);
}
unsigned long copy_in_user_fixup(void __user *to, void __user *from, unsigned long size)
{
unsigned long fault_addr = current_thread_info()->fault_address;
unsigned long start = (unsigned long) to;
unsigned long end = start + size;
if (fault_addr >= start && fault_addr < end)
return end - fault_addr;
start = (unsigned long) from;
end = start + size;
if (fault_addr >= start && fault_addr < end)
return end - fault_addr;
return size;
}
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