1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Memory preserving reboot related code. 4 * 5 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) 6 * Copyright (C) IBM Corporation, 2004. All rights reserved 7 */ 8 9 #include <linux/errno.h> 10 #include <linux/crash_dump.h> 11 #include <linux/uaccess.h> 12 #include <linux/io.h> 13 14 /** 15 * copy_oldmem_page - copy one page from "oldmem" 16 * @pfn: page frame number to be copied 17 * @buf: target memory address for the copy; this can be in kernel address 18 * space or user address space (see @userbuf) 19 * @csize: number of bytes to copy 20 * @offset: offset in bytes into the page (based on pfn) to begin the copy 21 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 22 * otherwise @buf is in kernel address space, use memcpy(). 23 * 24 * Copy a page from "oldmem". For this page, there is no pte mapped 25 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 26 */ 27 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 28 size_t csize, unsigned long offset, int userbuf) 29 { 30 void *vaddr; 31 32 if (!csize) 33 return 0; 34 35 vaddr = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE); 36 if (!vaddr) 37 return -ENOMEM; 38 39 if (userbuf) { 40 if (copy_to_user(buf, vaddr + offset, csize)) { 41 iounmap(vaddr); 42 return -EFAULT; 43 } 44 } else 45 memcpy(buf, vaddr + offset, csize); 46 47 set_iounmap_nonlazy(); 48 iounmap(vaddr); 49 return csize; 50 } 51