machine_kexec_32.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * handle transition of Linux booting another kernel
  4 * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
  5 */
  6
  7#include <linux/mm.h>
  8#include <linux/kexec.h>
  9#include <linux/delay.h>
 10#include <linux/numa.h>
 11#include <linux/ftrace.h>
 12#include <linux/suspend.h>
 13#include <linux/gfp.h>
 14#include <linux/io.h>
 15
 16#include <asm/pgalloc.h>
 17#include <asm/tlbflush.h>
 18#include <asm/mmu_context.h>
 19#include <asm/apic.h>
 20#include <asm/io_apic.h>
 21#include <asm/cpufeature.h>
 22#include <asm/desc.h>
 23#include <asm/set_memory.h>
 24#include <asm/debugreg.h>
 25
 26static void load_segments(void)
 27{
 28#define __STR(X) #X
 29#define STR(X) __STR(X)
 30
 31	__asm__ __volatile__ (
 32		"\tljmp $"STR(__KERNEL_CS)",$1f\n"
 33		"\t1:\n"
 34		"\tmovl $"STR(__KERNEL_DS)",%%eax\n"
 35		"\tmovl %%eax,%%ds\n"
 36		"\tmovl %%eax,%%es\n"
 37		"\tmovl %%eax,%%ss\n"
 38		: : : "eax", "memory");
 39#undef STR
 40#undef __STR
 41}
 42
 43static void machine_kexec_free_page_tables(struct kimage *image)
 44{
 45	free_pages((unsigned long)image->arch.pgd, pgd_allocation_order());
 46	image->arch.pgd = NULL;
 47#ifdef CONFIG_X86_PAE
 48	free_page((unsigned long)image->arch.pmd0);
 49	image->arch.pmd0 = NULL;
 50	free_page((unsigned long)image->arch.pmd1);
 51	image->arch.pmd1 = NULL;
 52#endif
 53	free_page((unsigned long)image->arch.pte0);
 54	image->arch.pte0 = NULL;
 55	free_page((unsigned long)image->arch.pte1);
 56	image->arch.pte1 = NULL;
 57}
 58
 59static int machine_kexec_alloc_page_tables(struct kimage *image)
 60{
 61	image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
 62						    pgd_allocation_order());
 63#ifdef CONFIG_X86_PAE
 64	image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 65	image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 66#endif
 67	image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
 68	image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
 69	if (!image->arch.pgd ||
 70#ifdef CONFIG_X86_PAE
 71	    !image->arch.pmd0 || !image->arch.pmd1 ||
 72#endif
 73	    !image->arch.pte0 || !image->arch.pte1) {
 74		return -ENOMEM;
 75	}
 76	return 0;
 77}
 78
 79static void machine_kexec_page_table_set_one(
 80	pgd_t *pgd, pmd_t *pmd, pte_t *pte,
 81	unsigned long vaddr, unsigned long paddr)
 82{
 83	p4d_t *p4d;
 84	pud_t *pud;
 85
 86	pgd += pgd_index(vaddr);
 87#ifdef CONFIG_X86_PAE
 88	if (!(pgd_val(*pgd) & _PAGE_PRESENT))
 89		set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
 90#endif
 91	p4d = p4d_offset(pgd, vaddr);
 92	pud = pud_offset(p4d, vaddr);
 93	pmd = pmd_offset(pud, vaddr);
 94	if (!(pmd_val(*pmd) & _PAGE_PRESENT))
 95		set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
 96	pte = pte_offset_kernel(pmd, vaddr);
 97	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
 98}
 99
100static void machine_kexec_prepare_page_tables(struct kimage *image)
101{
102	void *control_page;
103	pmd_t *pmd = NULL;
104
105	control_page = page_address(image->control_code_page);
106#ifdef CONFIG_X86_PAE
107	pmd = image->arch.pmd0;
108#endif
109	machine_kexec_page_table_set_one(
110		image->arch.pgd, pmd, image->arch.pte0,
111		(unsigned long)control_page, __pa(control_page));
112#ifdef CONFIG_X86_PAE
113	pmd = image->arch.pmd1;
114#endif
115	machine_kexec_page_table_set_one(
116		image->arch.pgd, pmd, image->arch.pte1,
117		__pa(control_page), __pa(control_page));
118}
119
120/*
121 * A architecture hook called to validate the
122 * proposed image and prepare the control pages
123 * as needed.  The pages for KEXEC_CONTROL_PAGE_SIZE
124 * have been allocated, but the segments have yet
125 * been copied into the kernel.
126 *
127 * Do what every setup is needed on image and the
128 * reboot code buffer to allow us to avoid allocations
129 * later.
130 *
131 * - Make control page executable.
132 * - Allocate page tables
133 * - Setup page tables
134 */
135int machine_kexec_prepare(struct kimage *image)
136{
137	int error;
138
139	set_memory_x((unsigned long)page_address(image->control_code_page), 1);
140	error = machine_kexec_alloc_page_tables(image);
141	if (error)
142		return error;
143	machine_kexec_prepare_page_tables(image);
144	return 0;
145}
146
147/*
148 * Undo anything leftover by machine_kexec_prepare
149 * when an image is freed.
150 */
151void machine_kexec_cleanup(struct kimage *image)
152{
153	set_memory_nx((unsigned long)page_address(image->control_code_page), 1);
154	machine_kexec_free_page_tables(image);
155}
156
157/*
158 * Do not allocate memory (or fail in any way) in machine_kexec().
159 * We are past the point of no return, committed to rebooting now.
160 */
161void machine_kexec(struct kimage *image)
162{
163	relocate_kernel_fn *relocate_kernel_ptr;
164	unsigned long page_list[PAGES_NR];
165	void *control_page;
166	int save_ftrace_enabled;
167
168#ifdef CONFIG_KEXEC_JUMP
169	if (image->preserve_context)
170		save_processor_state();
171#endif
172
173	save_ftrace_enabled = __ftrace_enabled_save();
174
175	/* Interrupts aren't acceptable while we reboot */
176	local_irq_disable();
177	hw_breakpoint_disable();
178
179	if (image->preserve_context) {
180#ifdef CONFIG_X86_IO_APIC
181		/*
182		 * We need to put APICs in legacy mode so that we can
183		 * get timer interrupts in second kernel. kexec/kdump
184		 * paths already have calls to restore_boot_irq_mode()
185		 * in one form or other. kexec jump path also need one.
186		 */
187		clear_IO_APIC();
188		restore_boot_irq_mode();
189#endif
190	}
191
192	control_page = page_address(image->control_code_page);
193	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
194
195	relocate_kernel_ptr = control_page;
196	page_list[PA_CONTROL_PAGE] = __pa(control_page);
197	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
198	page_list[PA_PGD] = __pa(image->arch.pgd);
199
200	if (image->type == KEXEC_TYPE_DEFAULT)
201		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
202						<< PAGE_SHIFT);
203
204	/*
205	 * The segment registers are funny things, they have both a
206	 * visible and an invisible part.  Whenever the visible part is
207	 * set to a specific selector, the invisible part is loaded
208	 * with from a table in memory.  At no other time is the
209	 * descriptor table in memory accessed.
210	 *
211	 * I take advantage of this here by force loading the
212	 * segments, before I zap the gdt with an invalid value.
213	 */
214	load_segments();
215	/*
216	 * The gdt & idt are now invalid.
217	 * If you want to load them you must set up your own idt & gdt.
218	 */
219	native_idt_invalidate();
220	native_gdt_invalidate();
221
222	/* now call it */
223	image->start = relocate_kernel_ptr((unsigned long)image->head,
224					   (unsigned long)page_list,
225					   image->start,
226					   boot_cpu_has(X86_FEATURE_PAE),
227					   image->preserve_context);
228
229#ifdef CONFIG_KEXEC_JUMP
230	if (image->preserve_context)
231		restore_processor_state();
232#endif
233
234	__ftrace_enabled_restore(save_ftrace_enabled);
235}