xref: /openbmc/linux/kernel/crash_dump.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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