1/*
2 * machine_kexec.c - handle transition of Linux booting another kernel
3 * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
4 *
5 * This source code is licensed under the GNU General Public License,
6 * Version 2.  See the file COPYING for more details.
7 */
8
9#include <linux/mm.h>
10#include <linux/kexec.h>
11#include <linux/delay.h>
12#include <linux/init.h>
13#include <asm/pgtable.h>
14#include <asm/pgalloc.h>
15#include <asm/tlbflush.h>
16#include <asm/mmu_context.h>
17#include <asm/io.h>
18#include <asm/apic.h>
19#include <asm/cpufeature.h>
20#include <asm/desc.h>
21#include <asm/system.h>
22
23#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
24static u32 kexec_pgd[1024] PAGE_ALIGNED;
25#ifdef CONFIG_X86_PAE
26static u32 kexec_pmd0[1024] PAGE_ALIGNED;
27static u32 kexec_pmd1[1024] PAGE_ALIGNED;
28#endif
29static u32 kexec_pte0[1024] PAGE_ALIGNED;
30static u32 kexec_pte1[1024] PAGE_ALIGNED;
31
32static void set_idt(void *newidt, __u16 limit)
33{
34	struct Xgt_desc_struct curidt;
35
36	/* ia32 supports unaliged loads & stores */
37	curidt.size    = limit;
38	curidt.address = (unsigned long)newidt;
39
40	load_idt(&curidt);
41};
42
43
44static void set_gdt(void *newgdt, __u16 limit)
45{
46	struct Xgt_desc_struct curgdt;
47
48	/* ia32 supports unaligned loads & stores */
49	curgdt.size    = limit;
50	curgdt.address = (unsigned long)newgdt;
51
52	load_gdt(&curgdt);
53};
54
55static void load_segments(void)
56{
57#define __STR(X) #X
58#define STR(X) __STR(X)
59
60	__asm__ __volatile__ (
61		"\tljmp $"STR(__KERNEL_CS)",$1f\n"
62		"\t1:\n"
63		"\tmovl $"STR(__KERNEL_DS)",%%eax\n"
64		"\tmovl %%eax,%%ds\n"
65		"\tmovl %%eax,%%es\n"
66		"\tmovl %%eax,%%fs\n"
67		"\tmovl %%eax,%%gs\n"
68		"\tmovl %%eax,%%ss\n"
69		::: "eax", "memory");
70#undef STR
71#undef __STR
72}
73
74/*
75 * A architecture hook called to validate the
76 * proposed image and prepare the control pages
77 * as needed.  The pages for KEXEC_CONTROL_CODE_SIZE
78 * have been allocated, but the segments have yet
79 * been copied into the kernel.
80 *
81 * Do what every setup is needed on image and the
82 * reboot code buffer to allow us to avoid allocations
83 * later.
84 *
85 * Currently nothing.
86 */
87int machine_kexec_prepare(struct kimage *image)
88{
89	return 0;
90}
91
92/*
93 * Undo anything leftover by machine_kexec_prepare
94 * when an image is freed.
95 */
96void machine_kexec_cleanup(struct kimage *image)
97{
98}
99
100/*
101 * Do not allocate memory (or fail in any way) in machine_kexec().
102 * We are past the point of no return, committed to rebooting now.
103 */
104NORET_TYPE void machine_kexec(struct kimage *image)
105{
106	unsigned long page_list[PAGES_NR];
107	void *control_page;
108
109	/* Interrupts aren't acceptable while we reboot */
110	local_irq_disable();
111
112	control_page = page_address(image->control_code_page);
113	memcpy(control_page, relocate_kernel, PAGE_SIZE);
114
115	page_list[PA_CONTROL_PAGE] = __pa(control_page);
116	page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
117	page_list[PA_PGD] = __pa(kexec_pgd);
118	page_list[VA_PGD] = (unsigned long)kexec_pgd;
119#ifdef CONFIG_X86_PAE
120	page_list[PA_PMD_0] = __pa(kexec_pmd0);
121	page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
122	page_list[PA_PMD_1] = __pa(kexec_pmd1);
123	page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
124#endif
125	page_list[PA_PTE_0] = __pa(kexec_pte0);
126	page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
127	page_list[PA_PTE_1] = __pa(kexec_pte1);
128	page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
129
130	/* The segment registers are funny things, they have both a
131	 * visible and an invisible part.  Whenever the visible part is
132	 * set to a specific selector, the invisible part is loaded
133	 * with from a table in memory.  At no other time is the
134	 * descriptor table in memory accessed.
135	 *
136	 * I take advantage of this here by force loading the
137	 * segments, before I zap the gdt with an invalid value.
138	 */
139	load_segments();
140	/* The gdt & idt are now invalid.
141	 * If you want to load them you must set up your own idt & gdt.
142	 */
143	set_gdt(phys_to_virt(0),0);
144	set_idt(phys_to_virt(0),0);
145
146	/* now call it */
147	relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
148			image->start, cpu_has_pae);
149}
150
151/* crashkernel=size@addr specifies the location to reserve for
152 * a crash kernel.  By reserving this memory we guarantee
153 * that linux never sets it up as a DMA target.
154 * Useful for holding code to do something appropriate
155 * after a kernel panic.
156 */
157static int __init parse_crashkernel(char *arg)
158{
159	unsigned long size, base;
160	size = memparse(arg, &arg);
161	if (*arg == '@') {
162		base = memparse(arg+1, &arg);
163		crashk_res.start = base;
164		crashk_res.end   = base + size - 1;
165	}
166	return 0;
167}
168early_param("crashkernel", parse_crashkernel);
169