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 <asm/uaccess.h> 11 12 /* Stores the physical address of elf header of crash image. */ 13 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; 14 15 /* 16 * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by 17 * is_kdump_kernel() to determine if we are booting after a panic. Hence 18 * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE. 19 * 20 * elfcorehdr= specifies the location of elf core header 21 * stored by the crashed kernel. 22 */ 23 static int __init parse_elfcorehdr(char *arg) 24 { 25 if (!arg) 26 return -EINVAL; 27 28 elfcorehdr_addr = memparse(arg, &arg); 29 30 return 0; 31 } 32 early_param("elfcorehdr", parse_elfcorehdr); 33 34 /** 35 * copy_oldmem_page - copy one page from "oldmem" 36 * @pfn: page frame number to be copied 37 * @buf: target memory address for the copy; this can be in kernel address 38 * space or user address space (see @userbuf) 39 * @csize: number of bytes to copy 40 * @offset: offset in bytes into the page (based on pfn) to begin the copy 41 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 42 * otherwise @buf is in kernel address space, use memcpy(). 43 * 44 * Copy a page from "oldmem". For this page, there is no pte mapped 45 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 46 */ 47 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 48 size_t csize, unsigned long offset, int userbuf) 49 { 50 void *vaddr; 51 52 if (!csize) 53 return 0; 54 55 vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE); 56 57 if (userbuf) { 58 if (copy_to_user(buf, (vaddr + offset), csize)) { 59 iounmap(vaddr); 60 return -EFAULT; 61 } 62 } else 63 memcpy(buf, (vaddr + offset), csize); 64 65 iounmap(vaddr); 66 return csize; 67 } 68