1/* 2 * relocate_kernel.S - put the kernel image in place to boot 3 * Copyright (C) 2002-2004 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/linkage.h> 10#include <asm/page_types.h> 11#include <asm/kexec.h> 12#include <asm/processor-flags.h> 13 14/* 15 * Must be relocatable PIC code callable as a C function 16 */ 17 18#define PTR(x) (x << 2) 19 20/* 21 * control_page + KEXEC_CONTROL_CODE_MAX_SIZE 22 * ~ control_page + PAGE_SIZE are used as data storage and stack for 23 * jumping back 24 */ 25#define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset)) 26 27/* Minimal CPU state */ 28#define ESP DATA(0x0) 29#define CR0 DATA(0x4) 30#define CR3 DATA(0x8) 31#define CR4 DATA(0xc) 32 33/* other data */ 34#define CP_VA_CONTROL_PAGE DATA(0x10) 35#define CP_PA_PGD DATA(0x14) 36#define CP_PA_SWAP_PAGE DATA(0x18) 37#define CP_PA_BACKUP_PAGES_MAP DATA(0x1c) 38 39 .text 40 .globl relocate_kernel 41relocate_kernel: 42 /* Save the CPU context, used for jumping back */ 43 44 pushl %ebx 45 pushl %esi 46 pushl %edi 47 pushl %ebp 48 pushf 49 50 movl 20+8(%esp), %ebp /* list of pages */ 51 movl PTR(VA_CONTROL_PAGE)(%ebp), %edi 52 movl %esp, ESP(%edi) 53 movl %cr0, %eax 54 movl %eax, CR0(%edi) 55 movl %cr3, %eax 56 movl %eax, CR3(%edi) 57 movl %cr4, %eax 58 movl %eax, CR4(%edi) 59 60 /* read the arguments and say goodbye to the stack */ 61 movl 20+4(%esp), %ebx /* page_list */ 62 movl 20+8(%esp), %ebp /* list of pages */ 63 movl 20+12(%esp), %edx /* start address */ 64 movl 20+16(%esp), %ecx /* cpu_has_pae */ 65 movl 20+20(%esp), %esi /* preserve_context */ 66 67 /* zero out flags, and disable interrupts */ 68 pushl $0 69 popfl 70 71 /* save some information for jumping back */ 72 movl PTR(VA_CONTROL_PAGE)(%ebp), %edi 73 movl %edi, CP_VA_CONTROL_PAGE(%edi) 74 movl PTR(PA_PGD)(%ebp), %eax 75 movl %eax, CP_PA_PGD(%edi) 76 movl PTR(PA_SWAP_PAGE)(%ebp), %eax 77 movl %eax, CP_PA_SWAP_PAGE(%edi) 78 movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi) 79 80 /* 81 * get physical address of control page now 82 * this is impossible after page table switch 83 */ 84 movl PTR(PA_CONTROL_PAGE)(%ebp), %edi 85 86 /* switch to new set of page tables */ 87 movl PTR(PA_PGD)(%ebp), %eax 88 movl %eax, %cr3 89 90 /* setup a new stack at the end of the physical control page */ 91 lea PAGE_SIZE(%edi), %esp 92 93 /* jump to identity mapped page */ 94 movl %edi, %eax 95 addl $(identity_mapped - relocate_kernel), %eax 96 pushl %eax 97 ret 98 99identity_mapped: 100 /* set return address to 0 if not preserving context */ 101 pushl $0 102 /* store the start address on the stack */ 103 pushl %edx 104 105 /* 106 * Set cr0 to a known state: 107 * - Paging disabled 108 * - Alignment check disabled 109 * - Write protect disabled 110 * - No task switch 111 * - Don't do FP software emulation. 112 * - Proctected mode enabled 113 */ 114 movl %cr0, %eax 115 andl $~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax 116 orl $(X86_CR0_PE), %eax 117 movl %eax, %cr0 118 119 /* clear cr4 if applicable */ 120 testl %ecx, %ecx 121 jz 1f 122 /* 123 * Set cr4 to a known state: 124 * Setting everything to zero seems safe. 125 */ 126 xorl %eax, %eax 127 movl %eax, %cr4 128 129 jmp 1f 1301: 131 132 /* Flush the TLB (needed?) */ 133 xorl %eax, %eax 134 movl %eax, %cr3 135 136 movl CP_PA_SWAP_PAGE(%edi), %eax 137 pushl %eax 138 pushl %ebx 139 call swap_pages 140 addl $8, %esp 141 142 /* 143 * To be certain of avoiding problems with self-modifying code 144 * I need to execute a serializing instruction here. 145 * So I flush the TLB, it's handy, and not processor dependent. 146 */ 147 xorl %eax, %eax 148 movl %eax, %cr3 149 150 /* 151 * set all of the registers to known values 152 * leave %esp alone 153 */ 154 155 testl %esi, %esi 156 jnz 1f 157 xorl %edi, %edi 158 xorl %eax, %eax 159 xorl %ebx, %ebx 160 xorl %ecx, %ecx 161 xorl %edx, %edx 162 xorl %esi, %esi 163 xorl %ebp, %ebp 164 ret 1651: 166 popl %edx 167 movl CP_PA_SWAP_PAGE(%edi), %esp 168 addl $PAGE_SIZE, %esp 1692: 170 call *%edx 171 172 /* get the re-entry point of the peer system */ 173 movl 0(%esp), %ebp 174 call 1f 1751: 176 popl %ebx 177 subl $(1b - relocate_kernel), %ebx 178 movl CP_VA_CONTROL_PAGE(%ebx), %edi 179 lea PAGE_SIZE(%ebx), %esp 180 movl CP_PA_SWAP_PAGE(%ebx), %eax 181 movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx 182 pushl %eax 183 pushl %edx 184 call swap_pages 185 addl $8, %esp 186 movl CP_PA_PGD(%ebx), %eax 187 movl %eax, %cr3 188 movl %cr0, %eax 189 orl $X86_CR0_PG, %eax 190 movl %eax, %cr0 191 lea PAGE_SIZE(%edi), %esp 192 movl %edi, %eax 193 addl $(virtual_mapped - relocate_kernel), %eax 194 pushl %eax 195 ret 196 197virtual_mapped: 198 movl CR4(%edi), %eax 199 movl %eax, %cr4 200 movl CR3(%edi), %eax 201 movl %eax, %cr3 202 movl CR0(%edi), %eax 203 movl %eax, %cr0 204 movl ESP(%edi), %esp 205 movl %ebp, %eax 206 207 popf 208 popl %ebp 209 popl %edi 210 popl %esi 211 popl %ebx 212 ret 213 214 /* Do the copies */ 215swap_pages: 216 movl 8(%esp), %edx 217 movl 4(%esp), %ecx 218 pushl %ebp 219 pushl %ebx 220 pushl %edi 221 pushl %esi 222 movl %ecx, %ebx 223 jmp 1f 224 2250: /* top, read another word from the indirection page */ 226 movl (%ebx), %ecx 227 addl $4, %ebx 2281: 229 testb $0x1, %cl /* is it a destination page */ 230 jz 2f 231 movl %ecx, %edi 232 andl $0xfffff000, %edi 233 jmp 0b 2342: 235 testb $0x2, %cl /* is it an indirection page */ 236 jz 2f 237 movl %ecx, %ebx 238 andl $0xfffff000, %ebx 239 jmp 0b 2402: 241 testb $0x4, %cl /* is it the done indicator */ 242 jz 2f 243 jmp 3f 2442: 245 testb $0x8, %cl /* is it the source indicator */ 246 jz 0b /* Ignore it otherwise */ 247 movl %ecx, %esi /* For every source page do a copy */ 248 andl $0xfffff000, %esi 249 250 movl %edi, %eax 251 movl %esi, %ebp 252 253 movl %edx, %edi 254 movl $1024, %ecx 255 rep ; movsl 256 257 movl %ebp, %edi 258 movl %eax, %esi 259 movl $1024, %ecx 260 rep ; movsl 261 262 movl %eax, %edi 263 movl %edx, %esi 264 movl $1024, %ecx 265 rep ; movsl 266 267 lea PAGE_SIZE(%ebp), %esi 268 jmp 0b 2693: 270 popl %esi 271 popl %edi 272 popl %ebx 273 popl %ebp 274 ret 275 276 .globl kexec_control_code_size 277.set kexec_control_code_size, . - relocate_kernel 278