1 /* 2 * crash_dump.c - Memory preserving reboot related code. 3 * 4 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) 5 * Copyright (C) IBM Corporation, 2004. All rights reserved 6 */ 7 #include <linux/errno.h> 8 #include <linux/crash_dump.h> 9 #include <linux/io.h> 10 #include <linux/uaccess.h> 11 12 /** 13 * copy_oldmem_page - copy one page from "oldmem" 14 * @pfn: page frame number to be copied 15 * @buf: target memory address for the copy; this can be in kernel address 16 * space or user address space (see @userbuf) 17 * @csize: number of bytes to copy 18 * @offset: offset in bytes into the page (based on pfn) to begin the copy 19 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 20 * otherwise @buf is in kernel address space, use memcpy(). 21 * 22 * Copy a page from "oldmem". For this page, there is no pte mapped 23 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 24 */ 25 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 26 size_t csize, unsigned long offset, int userbuf) 27 { 28 void *vaddr; 29 30 if (!csize) 31 return 0; 32 33 vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE); 34 35 if (userbuf) { 36 if (copy_to_user(buf, (vaddr + offset), csize)) { 37 iounmap(vaddr); 38 return -EFAULT; 39 } 40 } else 41 memcpy(buf, (vaddr + offset), csize); 42 43 iounmap(vaddr); 44 return csize; 45 } 46