1 /* 2 * 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 8 #include <linux/errno.h> 9 #include <linux/crash_dump.h> 10 #include <linux/uaccess.h> 11 #include <linux/io.h> 12 13 /* Stores the physical address of elf header of crash image. */ 14 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; 15 16 /** 17 * copy_oldmem_page - copy one page from "oldmem" 18 * @pfn: page frame number to be copied 19 * @buf: target memory address for the copy; this can be in kernel address 20 * space or user address space (see @userbuf) 21 * @csize: number of bytes to copy 22 * @offset: offset in bytes into the page (based on pfn) to begin the copy 23 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 24 * otherwise @buf is in kernel address space, use memcpy(). 25 * 26 * Copy a page from "oldmem". For this page, there is no pte mapped 27 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 28 */ 29 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 30 size_t csize, unsigned long offset, int userbuf) 31 { 32 void *vaddr; 33 34 if (!csize) 35 return 0; 36 37 vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE); 38 if (!vaddr) 39 return -ENOMEM; 40 41 if (userbuf) { 42 if (copy_to_user(buf, vaddr + offset, csize)) { 43 iounmap(vaddr); 44 return -EFAULT; 45 } 46 } else 47 memcpy(buf, vaddr + offset, csize); 48 49 iounmap(vaddr); 50 return csize; 51 } 52