1/*
2 * Routines for doing kexec-based kdump.
3 *
4 * Copyright (C) 2005, IBM Corp.
5 *
6 * Created by: Michael Ellerman
7 *
8 * This source code is licensed under the GNU General Public License,
9 * Version 2.  See the file COPYING for more details.
10 */
11
12#undef DEBUG
13
14#include <linux/crash_dump.h>
15#include <linux/bootmem.h>
16#include <asm/kdump.h>
17#include <asm/lmb.h>
18#include <asm/firmware.h>
19#include <asm/uaccess.h>
20
21#ifdef DEBUG
22#include <asm/udbg.h>
23#define DBG(fmt...) udbg_printf(fmt)
24#else
25#define DBG(fmt...)
26#endif
27
28void reserve_kdump_trampoline(void)
29{
30	lmb_reserve(0, KDUMP_RESERVE_LIMIT);
31}
32
33static void __init create_trampoline(unsigned long addr)
34{
35	/* The maximum range of a single instruction branch, is the current
36	 * instruction's address + (32 MB - 4) bytes. For the trampoline we
37	 * need to branch to current address + 32 MB. So we insert a nop at
38	 * the trampoline address, then the next instruction (+ 4 bytes)
39	 * does a branch to (32 MB - 4). The net effect is that when we
40	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
41	 * two instructions it doesn't require any registers.
42	 */
43	create_instruction(addr, 0x60000000); /* nop */
44	create_branch(addr + 4, addr + PHYSICAL_START, 0);
45}
46
47void __init setup_kdump_trampoline(void)
48{
49	unsigned long i;
50
51	DBG(" -> setup_kdump_trampoline()\n");
52
53	for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
54		create_trampoline(i);
55	}
56
57	create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
58	create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
59
60	DBG(" <- setup_kdump_trampoline()\n");
61}
62
63#ifdef CONFIG_PROC_VMCORE
64static int __init parse_elfcorehdr(char *p)
65{
66	if (p)
67		elfcorehdr_addr = memparse(p, &p);
68
69	return 1;
70}
71__setup("elfcorehdr=", parse_elfcorehdr);
72#endif
73
74static int __init parse_savemaxmem(char *p)
75{
76	if (p)
77		saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
78
79	return 1;
80}
81__setup("savemaxmem=", parse_savemaxmem);
82
83/**
84 * copy_oldmem_page - copy one page from "oldmem"
85 * @pfn: page frame number to be copied
86 * @buf: target memory address for the copy; this can be in kernel address
87 *      space or user address space (see @userbuf)
88 * @csize: number of bytes to copy
89 * @offset: offset in bytes into the page (based on pfn) to begin the copy
90 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
91 *      otherwise @buf is in kernel address space, use memcpy().
92 *
93 * Copy a page from "oldmem". For this page, there is no pte mapped
94 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
95 */
96ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
97			size_t csize, unsigned long offset, int userbuf)
98{
99	void  *vaddr;
100
101	if (!csize)
102		return 0;
103
104	vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
105
106	if (userbuf) {
107		if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) {
108			iounmap(vaddr);
109			return -EFAULT;
110		}
111	} else
112		memcpy(buf, (vaddr + offset), csize);
113
114	iounmap(vaddr);
115	return csize;
116}
117