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/io.h>
16#include <linux/memblock.h>
17#include <asm/code-patching.h>
18#include <asm/kdump.h>
19#include <asm/prom.h>
20#include <asm/firmware.h>
21#include <asm/uaccess.h>
22#include <asm/rtas.h>
23
24#ifdef DEBUG
25#include <asm/udbg.h>
26#define DBG(fmt...) udbg_printf(fmt)
27#else
28#define DBG(fmt...)
29#endif
30
31#ifndef CONFIG_NONSTATIC_KERNEL
32void __init reserve_kdump_trampoline(void)
33{
34	memblock_reserve(0, KDUMP_RESERVE_LIMIT);
35}
36
37static void __init create_trampoline(unsigned long addr)
38{
39	unsigned int *p = (unsigned int *)addr;
40
41	/* The maximum range of a single instruction branch, is the current
42	 * instruction's address + (32 MB - 4) bytes. For the trampoline we
43	 * need to branch to current address + 32 MB. So we insert a nop at
44	 * the trampoline address, then the next instruction (+ 4 bytes)
45	 * does a branch to (32 MB - 4). The net effect is that when we
46	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
47	 * two instructions it doesn't require any registers.
48	 */
49	patch_instruction(p, PPC_INST_NOP);
50	patch_branch(++p, addr + PHYSICAL_START, 0);
51}
52
53void __init setup_kdump_trampoline(void)
54{
55	unsigned long i;
56
57	DBG(" -> setup_kdump_trampoline()\n");
58
59	for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
60		create_trampoline(i);
61	}
62
63#ifdef CONFIG_PPC_PSERIES
64	create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
65	create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
66#endif /* CONFIG_PPC_PSERIES */
67
68	DBG(" <- setup_kdump_trampoline()\n");
69}
70#endif /* CONFIG_NONSTATIC_KERNEL */
71
72static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
73                               unsigned long offset, int userbuf)
74{
75	if (userbuf) {
76		if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
77			return -EFAULT;
78	} else
79		memcpy(buf, (vaddr + offset), csize);
80
81	return csize;
82}
83
84/**
85 * copy_oldmem_page - copy one page from "oldmem"
86 * @pfn: page frame number to be copied
87 * @buf: target memory address for the copy; this can be in kernel address
88 *      space or user address space (see @userbuf)
89 * @csize: number of bytes to copy
90 * @offset: offset in bytes into the page (based on pfn) to begin the copy
91 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
92 *      otherwise @buf is in kernel address space, use memcpy().
93 *
94 * Copy a page from "oldmem". For this page, there is no pte mapped
95 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
96 */
97ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
98			size_t csize, unsigned long offset, int userbuf)
99{
100	void  *vaddr;
101	phys_addr_t paddr;
102
103	if (!csize)
104		return 0;
105
106	csize = min_t(size_t, csize, PAGE_SIZE);
107	paddr = pfn << PAGE_SHIFT;
108
109	if (memblock_is_region_memory(paddr, csize)) {
110		vaddr = __va(paddr);
111		csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
112	} else {
113		vaddr = __ioremap(paddr, PAGE_SIZE, 0);
114		csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
115		iounmap(vaddr);
116	}
117
118	return csize;
119}
120
121#ifdef CONFIG_PPC_RTAS
122/*
123 * The crashkernel region will almost always overlap the RTAS region, so
124 * we have to be careful when shrinking the crashkernel region.
125 */
126void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
127{
128	unsigned long addr;
129	const __be32 *basep, *sizep;
130	unsigned int rtas_start = 0, rtas_end = 0;
131
132	basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
133	sizep = of_get_property(rtas.dev, "rtas-size", NULL);
134
135	if (basep && sizep) {
136		rtas_start = be32_to_cpup(basep);
137		rtas_end = rtas_start + be32_to_cpup(sizep);
138	}
139
140	for (addr = begin; addr < end; addr += PAGE_SIZE) {
141		/* Does this page overlap with the RTAS region? */
142		if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
143			continue;
144
145		free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
146	}
147}
148#endif
149