/* *	kernel/crash_dump.c - Memory preserving reboot related code. * *	Created by: Hariprasad Nellitheertha (hari@in.ibm.com) *	Copyright (C) IBM Corporation, 2004. All rights reserved */ #include <linux/smp_lock.h>#include <linux/errno.h>#include <linux/proc_fs.h>#include <linux/bootmem.h>#include <linux/highmem.h>#include <linux/crash_dump.h> #include <asm/io.h>#include <asm/uaccess.h> /* Stores the physical address of elf header of crash image. */unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; /** * copy_oldmem_page - copy one page from "oldmem" * @pfn: page frame number to be copied * @buf: target memory address for the copy; this can be in kernel address *	space or user address space (see @userbuf) * @csize: number of bytes to copy * @offset: offset in bytes into the page (based on pfn) to begin the copy * @userbuf: if set, @buf is in user address space, use copy_to_user(), *	otherwise @buf is in kernel address space, use memcpy(). * * Copy a page from "oldmem". For this page, there is no pte mapped * in the current kernel. We stitch up a pte, similar to kmap_atomic. */ssize_t copy_oldmem_page(unsigned long pfn, char *buf,				size_t csize, unsigned long offset, int userbuf){	void *page, *vaddr; 	if (!csize)		return 0; 	page = kmalloc(PAGE_SIZE, GFP_KERNEL);	if (!page)		return -ENOMEM; 	vaddr = kmap_atomic_pfn(pfn, KM_PTE0);	copy_page(page, vaddr);	kunmap_atomic(vaddr, KM_PTE0); 	if (userbuf) {		if (copy_to_user(buf, (page + offset), csize)) {			kfree(page);			return -EFAULT;		}	} else {		memcpy(buf, (page + offset), csize);	} 	kfree(page);	return csize;}