xref: /openbmc/linux/arch/sh/kernel/crash_dump.c (revision 4800cd83)
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