1 /* 2 * kernel/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 8 #include <linux/smp_lock.h> 9 #include <linux/errno.h> 10 #include <linux/proc_fs.h> 11 #include <linux/bootmem.h> 12 #include <linux/highmem.h> 13 #include <linux/crash_dump.h> 14 15 #include <asm/io.h> 16 #include <asm/uaccess.h> 17 18 /* Stores the physical address of elf header of crash image. */ 19 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; 20 21 /** 22 * copy_oldmem_page - copy one page from "oldmem" 23 * @pfn: page frame number to be copied 24 * @buf: target memory address for the copy; this can be in kernel address 25 * space or user address space (see @userbuf) 26 * @csize: number of bytes to copy 27 * @offset: offset in bytes into the page (based on pfn) to begin the copy 28 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 29 * otherwise @buf is in kernel address space, use memcpy(). 30 * 31 * Copy a page from "oldmem". For this page, there is no pte mapped 32 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 33 */ 34 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 35 size_t csize, unsigned long offset, int userbuf) 36 { 37 void *page, *vaddr; 38 39 if (!csize) 40 return 0; 41 42 page = kmalloc(PAGE_SIZE, GFP_KERNEL); 43 if (!page) 44 return -ENOMEM; 45 46 vaddr = kmap_atomic_pfn(pfn, KM_PTE0); 47 copy_page(page, vaddr); 48 kunmap_atomic(vaddr, KM_PTE0); 49 50 if (userbuf) { 51 if (copy_to_user(buf, (page + offset), csize)) { 52 kfree(page); 53 return -EFAULT; 54 } 55 } else { 56 memcpy(buf, (page + offset), csize); 57 } 58 59 kfree(page); 60 return csize; 61 } 62