1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * relocate_kernel.S - put the kernel image in place to boot
4 * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
7 #include <linux/linkage.h>
8 #include <asm/page_types.h>
10 #include <asm/processor-flags.h>
13 * Must be relocatable PIC code callable as a C function
16 #define PTR(x) (x << 2)
19 * control_page + KEXEC_CONTROL_CODE_MAX_SIZE
20 * ~ control_page + PAGE_SIZE are used as data storage and stack for
23 #define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
25 /* Minimal CPU state */
32 #define CP_VA_CONTROL_PAGE DATA(0x10)
33 #define CP_PA_PGD DATA(0x14)
34 #define CP_PA_SWAP_PAGE DATA(0x18)
35 #define CP_PA_BACKUP_PAGES_MAP DATA(0x1c)
38 .globl relocate_kernel
40 /* Save the CPU context, used for jumping back */
48 movl 20+8(%esp), %ebp /* list of pages */
49 movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
58 /* read the arguments and say goodbye to the stack */
59 movl 20+4(%esp), %ebx /* page_list */
60 movl 20+8(%esp), %ebp /* list of pages */
61 movl 20+12(%esp), %edx /* start address */
62 movl 20+16(%esp), %ecx /* cpu_has_pae */
63 movl 20+20(%esp), %esi /* preserve_context */
65 /* zero out flags, and disable interrupts */
69 /* save some information for jumping back */
70 movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
71 movl %edi, CP_VA_CONTROL_PAGE(%edi)
72 movl PTR(PA_PGD)(%ebp), %eax
73 movl %eax, CP_PA_PGD(%edi)
74 movl PTR(PA_SWAP_PAGE)(%ebp), %eax
75 movl %eax, CP_PA_SWAP_PAGE(%edi)
76 movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
79 * get physical address of control page now
80 * this is impossible after page table switch
82 movl PTR(PA_CONTROL_PAGE)(%ebp), %edi
84 /* switch to new set of page tables */
85 movl PTR(PA_PGD)(%ebp), %eax
88 /* setup a new stack at the end of the physical control page */
89 lea PAGE_SIZE(%edi), %esp
91 /* jump to identity mapped page */
93 addl $(identity_mapped - relocate_kernel), %eax
98 /* set return address to 0 if not preserving context */
100 /* store the start address on the stack */
104 * Set cr0 to a known state:
106 * - Alignment check disabled
107 * - Write protect disabled
109 * - Don't do FP software emulation.
110 * - Proctected mode enabled
113 andl $~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax
114 orl $(X86_CR0_PE), %eax
117 /* clear cr4 if applicable */
121 * Set cr4 to a known state:
122 * Setting everything to zero seems safe.
130 /* Flush the TLB (needed?) */
134 movl CP_PA_SWAP_PAGE(%edi), %eax
141 * To be certain of avoiding problems with self-modifying code
142 * I need to execute a serializing instruction here.
143 * So I flush the TLB, it's handy, and not processor dependent.
149 * set all of the registers to known values
165 movl CP_PA_SWAP_PAGE(%edi), %esp
166 addl $PAGE_SIZE, %esp
170 /* get the re-entry point of the peer system */
175 subl $(1b - relocate_kernel), %ebx
176 movl CP_VA_CONTROL_PAGE(%ebx), %edi
177 lea PAGE_SIZE(%ebx), %esp
178 movl CP_PA_SWAP_PAGE(%ebx), %eax
179 movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
184 movl CP_PA_PGD(%ebx), %eax
187 orl $X86_CR0_PG, %eax
189 lea PAGE_SIZE(%edi), %esp
191 addl $(virtual_mapped - relocate_kernel), %eax
223 0: /* top, read another word from the indirection page */
227 testb $0x1, %cl /* is it a destination page */
230 andl $0xfffff000, %edi
233 testb $0x2, %cl /* is it an indirection page */
236 andl $0xfffff000, %ebx
239 testb $0x4, %cl /* is it the done indicator */
243 testb $0x8, %cl /* is it the source indicator */
244 jz 0b /* Ignore it otherwise */
245 movl %ecx, %esi /* For every source page do a copy */
246 andl $0xfffff000, %esi
265 lea PAGE_SIZE(%ebp), %esi
274 .globl kexec_control_code_size
275 .set kexec_control_code_size, . - relocate_kernel