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/string.h>
12#include <linux/reboot.h>
13#include <asm/pgtable.h>
14#include <asm/tlbflush.h>
15#include <asm/mmu_context.h>
16#include <asm/io.h>
17
18#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
19static u64 kexec_pgd[512] PAGE_ALIGNED;
20static u64 kexec_pud0[512] PAGE_ALIGNED;
21static u64 kexec_pmd0[512] PAGE_ALIGNED;
22static u64 kexec_pte0[512] PAGE_ALIGNED;
23static u64 kexec_pud1[512] PAGE_ALIGNED;
24static u64 kexec_pmd1[512] PAGE_ALIGNED;
25static u64 kexec_pte1[512] PAGE_ALIGNED;
26
27static void init_level2_page(pmd_t *level2p, unsigned long addr)
28{
29	unsigned long end_addr;
30
31	addr &= PAGE_MASK;
32	end_addr = addr + PUD_SIZE;
33	while (addr < end_addr) {
34		set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
35		addr += PMD_SIZE;
36	}
37}
38
39static int init_level3_page(struct kimage *image, pud_t *level3p,
40				unsigned long addr, unsigned long last_addr)
41{
42	unsigned long end_addr;
43	int result;
44
45	result = 0;
46	addr &= PAGE_MASK;
47	end_addr = addr + PGDIR_SIZE;
48	while ((addr < last_addr) && (addr < end_addr)) {
49		struct page *page;
50		pmd_t *level2p;
51
52		page = kimage_alloc_control_pages(image, 0);
53		if (!page) {
54			result = -ENOMEM;
55			goto out;
56		}
57		level2p = (pmd_t *)page_address(page);
58		init_level2_page(level2p, addr);
59		set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
60		addr += PUD_SIZE;
61	}
62	/* clear the unused entries */
63	while (addr < end_addr) {
64		pud_clear(level3p++);
65		addr += PUD_SIZE;
66	}
67out:
68	return result;
69}
70
71
72static int init_level4_page(struct kimage *image, pgd_t *level4p,
73				unsigned long addr, unsigned long last_addr)
74{
75	unsigned long end_addr;
76	int result;
77
78	result = 0;
79	addr &= PAGE_MASK;
80	end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
81	while ((addr < last_addr) && (addr < end_addr)) {
82		struct page *page;
83		pud_t *level3p;
84
85		page = kimage_alloc_control_pages(image, 0);
86		if (!page) {
87			result = -ENOMEM;
88			goto out;
89		}
90		level3p = (pud_t *)page_address(page);
91		result = init_level3_page(image, level3p, addr, last_addr);
92		if (result) {
93			goto out;
94		}
95		set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
96		addr += PGDIR_SIZE;
97	}
98	/* clear the unused entries */
99	while (addr < end_addr) {
100		pgd_clear(level4p++);
101		addr += PGDIR_SIZE;
102	}
103out:
104	return result;
105}
106
107
108static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
109{
110	pgd_t *level4p;
111	level4p = (pgd_t *)__va(start_pgtable);
112 	return init_level4_page(image, level4p, 0, end_pfn << PAGE_SHIFT);
113}
114
115static void set_idt(void *newidt, u16 limit)
116{
117	struct desc_ptr curidt;
118
119	/* x86-64 supports unaliged loads & stores */
120	curidt.size    = limit;
121	curidt.address = (unsigned long)newidt;
122
123	__asm__ __volatile__ (
124		"lidtq %0\n"
125		: : "m" (curidt)
126		);
127};
128
129
130static void set_gdt(void *newgdt, u16 limit)
131{
132	struct desc_ptr curgdt;
133
134	/* x86-64 supports unaligned loads & stores */
135	curgdt.size    = limit;
136	curgdt.address = (unsigned long)newgdt;
137
138	__asm__ __volatile__ (
139		"lgdtq %0\n"
140		: : "m" (curgdt)
141		);
142};
143
144static void load_segments(void)
145{
146	__asm__ __volatile__ (
147		"\tmovl %0,%%ds\n"
148		"\tmovl %0,%%es\n"
149		"\tmovl %0,%%ss\n"
150		"\tmovl %0,%%fs\n"
151		"\tmovl %0,%%gs\n"
152		: : "a" (__KERNEL_DS) : "memory"
153		);
154}
155
156int machine_kexec_prepare(struct kimage *image)
157{
158	unsigned long start_pgtable;
159	int result;
160
161	/* Calculate the offsets */
162	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
163
164	/* Setup the identity mapped 64bit page table */
165	result = init_pgtable(image, start_pgtable);
166	if (result)
167		return result;
168
169	return 0;
170}
171
172void machine_kexec_cleanup(struct kimage *image)
173{
174	return;
175}
176
177/*
178 * Do not allocate memory (or fail in any way) in machine_kexec().
179 * We are past the point of no return, committed to rebooting now.
180 */
181NORET_TYPE void machine_kexec(struct kimage *image)
182{
183	unsigned long page_list[PAGES_NR];
184	void *control_page;
185
186	/* Interrupts aren't acceptable while we reboot */
187	local_irq_disable();
188
189	control_page = page_address(image->control_code_page) + PAGE_SIZE;
190	memcpy(control_page, relocate_kernel, PAGE_SIZE);
191
192	page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
193	page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
194	page_list[PA_PGD] = virt_to_phys(&kexec_pgd);
195	page_list[VA_PGD] = (unsigned long)kexec_pgd;
196	page_list[PA_PUD_0] = virt_to_phys(&kexec_pud0);
197	page_list[VA_PUD_0] = (unsigned long)kexec_pud0;
198	page_list[PA_PMD_0] = virt_to_phys(&kexec_pmd0);
199	page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
200	page_list[PA_PTE_0] = virt_to_phys(&kexec_pte0);
201	page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
202	page_list[PA_PUD_1] = virt_to_phys(&kexec_pud1);
203	page_list[VA_PUD_1] = (unsigned long)kexec_pud1;
204	page_list[PA_PMD_1] = virt_to_phys(&kexec_pmd1);
205	page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
206	page_list[PA_PTE_1] = virt_to_phys(&kexec_pte1);
207	page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
208
209	page_list[PA_TABLE_PAGE] =
210	  (unsigned long)__pa(page_address(image->control_code_page));
211
212	/* The segment registers are funny things, they have both a
213	 * visible and an invisible part.  Whenever the visible part is
214	 * set to a specific selector, the invisible part is loaded
215	 * with from a table in memory.  At no other time is the
216	 * descriptor table in memory accessed.
217	 *
218	 * I take advantage of this here by force loading the
219	 * segments, before I zap the gdt with an invalid value.
220	 */
221	load_segments();
222	/* The gdt & idt are now invalid.
223	 * If you want to load them you must set up your own idt & gdt.
224	 */
225	set_gdt(phys_to_virt(0),0);
226	set_idt(phys_to_virt(0),0);
227
228	/* now call it */
229	relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
230			image->start);
231}
232
233/* crashkernel=size@addr specifies the location to reserve for
234 * a crash kernel.  By reserving this memory we guarantee
235 * that linux never set's it up as a DMA target.
236 * Useful for holding code to do something appropriate
237 * after a kernel panic.
238 */
239static int __init setup_crashkernel(char *arg)
240{
241	unsigned long size, base;
242	char *p;
243	if (!arg)
244		return -EINVAL;
245	size = memparse(arg, &p);
246	if (arg == p)
247		return -EINVAL;
248	if (*p == '@') {
249		base = memparse(p+1, &p);
250		crashk_res.start = base;
251		crashk_res.end   = base + size - 1;
252	}
253	return 0;
254}
255early_param("crashkernel", setup_crashkernel);
256