/* 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; }