xref: /openbmc/linux/arch/powerpc/kernel/crash_dump.c (revision 22246614)
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 <linux/lmb.h>
17 #include <asm/kdump.h>
18 #include <asm/prom.h>
19 #include <asm/firmware.h>
20 #include <asm/uaccess.h>
21 
22 #ifdef DEBUG
23 #include <asm/udbg.h>
24 #define DBG(fmt...) udbg_printf(fmt)
25 #else
26 #define DBG(fmt...)
27 #endif
28 
29 void __init reserve_kdump_trampoline(void)
30 {
31 	lmb_reserve(0, KDUMP_RESERVE_LIMIT);
32 }
33 
34 static void __init create_trampoline(unsigned long addr)
35 {
36 	/* The maximum range of a single instruction branch, is the current
37 	 * instruction's address + (32 MB - 4) bytes. For the trampoline we
38 	 * need to branch to current address + 32 MB. So we insert a nop at
39 	 * the trampoline address, then the next instruction (+ 4 bytes)
40 	 * does a branch to (32 MB - 4). The net effect is that when we
41 	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
42 	 * two instructions it doesn't require any registers.
43 	 */
44 	create_instruction(addr, 0x60000000); /* nop */
45 	create_branch(addr + 4, addr + PHYSICAL_START, 0);
46 }
47 
48 void __init setup_kdump_trampoline(void)
49 {
50 	unsigned long i;
51 
52 	DBG(" -> setup_kdump_trampoline()\n");
53 
54 	for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
55 		create_trampoline(i);
56 	}
57 
58 #ifdef CONFIG_PPC_PSERIES
59 	create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
60 	create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
61 #endif /* CONFIG_PPC_PSERIES */
62 
63 	DBG(" <- setup_kdump_trampoline()\n");
64 }
65 
66 #ifdef CONFIG_PROC_VMCORE
67 static int __init parse_elfcorehdr(char *p)
68 {
69 	if (p)
70 		elfcorehdr_addr = memparse(p, &p);
71 
72 	return 1;
73 }
74 __setup("elfcorehdr=", parse_elfcorehdr);
75 #endif
76 
77 static int __init parse_savemaxmem(char *p)
78 {
79 	if (p)
80 		saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
81 
82 	return 1;
83 }
84 __setup("savemaxmem=", parse_savemaxmem);
85 
86 /**
87  * copy_oldmem_page - copy one page from "oldmem"
88  * @pfn: page frame number to be copied
89  * @buf: target memory address for the copy; this can be in kernel address
90  *      space or user address space (see @userbuf)
91  * @csize: number of bytes to copy
92  * @offset: offset in bytes into the page (based on pfn) to begin the copy
93  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
94  *      otherwise @buf is in kernel address space, use memcpy().
95  *
96  * Copy a page from "oldmem". For this page, there is no pte mapped
97  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
98  */
99 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
100 			size_t csize, unsigned long offset, int userbuf)
101 {
102 	void  *vaddr;
103 
104 	if (!csize)
105 		return 0;
106 
107 	vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
108 
109 	if (userbuf) {
110 		if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) {
111 			iounmap(vaddr);
112 			return -EFAULT;
113 		}
114 	} else
115 		memcpy(buf, (vaddr + offset), csize);
116 
117 	iounmap(vaddr);
118 	return csize;
119 }
120