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.h> 11#include <asm/kexec.h> 12#include <asm/processor-flags.h> 13#include <asm/pgtable.h> 14 15/* 16 * Must be relocatable PIC code callable as a C function 17 */ 18 19#define PTR(x) (x << 2) 20#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY) 21#define PAE_PGD_ATTR (_PAGE_PRESENT) 22 23/* control_page + PAGE_SIZE/2 ~ control_page + PAGE_SIZE * 3/4 are 24 * used to save some data for jumping back 25 */ 26#define DATA(offset) (PAGE_SIZE/2+(offset)) 27 28/* Minimal CPU state */ 29#define ESP DATA(0x0) 30#define CR0 DATA(0x4) 31#define CR3 DATA(0x8) 32#define CR4 DATA(0xc) 33 34/* other data */ 35#define CP_VA_CONTROL_PAGE DATA(0x10) 36#define CP_PA_PGD DATA(0x14) 37#define CP_PA_SWAP_PAGE DATA(0x18) 38#define CP_PA_BACKUP_PAGES_MAP DATA(0x1c) 39 40 .text 41 .align PAGE_SIZE 42 .globl relocate_kernel 43relocate_kernel: 44 /* Save the CPU context, used for jumping back */ 45 46 pushl %ebx 47 pushl %esi 48 pushl %edi 49 pushl %ebp 50 pushf 51 52 movl 20+8(%esp), %ebp /* list of pages */ 53 movl PTR(VA_CONTROL_PAGE)(%ebp), %edi 54 movl %esp, ESP(%edi) 55 movl %cr0, %eax 56 movl %eax, CR0(%edi) 57 movl %cr3, %eax 58 movl %eax, CR3(%edi) 59 movl %cr4, %eax 60 movl %eax, CR4(%edi) 61 62#ifdef CONFIG_X86_PAE 63 /* map the control page at its virtual address */ 64 65 movl PTR(VA_PGD)(%ebp), %edi 66 movl PTR(VA_CONTROL_PAGE)(%ebp), %eax 67 andl $0xc0000000, %eax 68 shrl $27, %eax 69 addl %edi, %eax 70 71 movl PTR(PA_PMD_0)(%ebp), %edx 72 orl $PAE_PGD_ATTR, %edx 73 movl %edx, (%eax) 74 75 movl PTR(VA_PMD_0)(%ebp), %edi 76 movl PTR(VA_CONTROL_PAGE)(%ebp), %eax 77 andl $0x3fe00000, %eax 78 shrl $18, %eax 79 addl %edi, %eax 80 81 movl PTR(PA_PTE_0)(%ebp), %edx 82 orl $PAGE_ATTR, %edx 83 movl %edx, (%eax) 84 85 movl PTR(VA_PTE_0)(%ebp), %edi 86 movl PTR(VA_CONTROL_PAGE)(%ebp), %eax 87 andl $0x001ff000, %eax 88 shrl $9, %eax 89 addl %edi, %eax 90 91 movl PTR(PA_CONTROL_PAGE)(%ebp), %edx 92 orl $PAGE_ATTR, %edx 93 movl %edx, (%eax) 94 95 /* identity map the control page at its physical address */ 96 97 movl PTR(VA_PGD)(%ebp), %edi 98 movl PTR(PA_CONTROL_PAGE)(%ebp), %eax 99 andl $0xc0000000, %eax 100 shrl $27, %eax 101 addl %edi, %eax 102 103 movl PTR(PA_PMD_1)(%ebp), %edx 104 orl $PAE_PGD_ATTR, %edx 105 movl %edx, (%eax) 106 107 movl PTR(VA_PMD_1)(%ebp), %edi 108 movl PTR(PA_CONTROL_PAGE)(%ebp), %eax 109 andl $0x3fe00000, %eax 110 shrl $18, %eax 111 addl %edi, %eax 112 113 movl PTR(PA_PTE_1)(%ebp), %edx 114 orl $PAGE_ATTR, %edx 115 movl %edx, (%eax) 116 117 movl PTR(VA_PTE_1)(%ebp), %edi 118 movl PTR(PA_CONTROL_PAGE)(%ebp), %eax 119 andl $0x001ff000, %eax 120 shrl $9, %eax 121 addl %edi, %eax 122 123 movl PTR(PA_CONTROL_PAGE)(%ebp), %edx 124 orl $PAGE_ATTR, %edx 125 movl %edx, (%eax) 126#else 127 /* map the control page at its virtual address */ 128 129 movl PTR(VA_PGD)(%ebp), %edi 130 movl PTR(VA_CONTROL_PAGE)(%ebp), %eax 131 andl $0xffc00000, %eax 132 shrl $20, %eax 133 addl %edi, %eax 134 135 movl PTR(PA_PTE_0)(%ebp), %edx 136 orl $PAGE_ATTR, %edx 137 movl %edx, (%eax) 138 139 movl PTR(VA_PTE_0)(%ebp), %edi 140 movl PTR(VA_CONTROL_PAGE)(%ebp), %eax 141 andl $0x003ff000, %eax 142 shrl $10, %eax 143 addl %edi, %eax 144 145 movl PTR(PA_CONTROL_PAGE)(%ebp), %edx 146 orl $PAGE_ATTR, %edx 147 movl %edx, (%eax) 148 149 /* identity map the control page at its physical address */ 150 151 movl PTR(VA_PGD)(%ebp), %edi 152 movl PTR(PA_CONTROL_PAGE)(%ebp), %eax 153 andl $0xffc00000, %eax 154 shrl $20, %eax 155 addl %edi, %eax 156 157 movl PTR(PA_PTE_1)(%ebp), %edx 158 orl $PAGE_ATTR, %edx 159 movl %edx, (%eax) 160 161 movl PTR(VA_PTE_1)(%ebp), %edi 162 movl PTR(PA_CONTROL_PAGE)(%ebp), %eax 163 andl $0x003ff000, %eax 164 shrl $10, %eax 165 addl %edi, %eax 166 167 movl PTR(PA_CONTROL_PAGE)(%ebp), %edx 168 orl $PAGE_ATTR, %edx 169 movl %edx, (%eax) 170#endif 171 172relocate_new_kernel: 173 /* read the arguments and say goodbye to the stack */ 174 movl 20+4(%esp), %ebx /* page_list */ 175 movl 20+8(%esp), %ebp /* list of pages */ 176 movl 20+12(%esp), %edx /* start address */ 177 movl 20+16(%esp), %ecx /* cpu_has_pae */ 178 movl 20+20(%esp), %esi /* preserve_context */ 179 180 /* zero out flags, and disable interrupts */ 181 pushl $0 182 popfl 183 184 /* save some information for jumping back */ 185 movl PTR(VA_CONTROL_PAGE)(%ebp), %edi 186 movl %edi, CP_VA_CONTROL_PAGE(%edi) 187 movl PTR(PA_PGD)(%ebp), %eax 188 movl %eax, CP_PA_PGD(%edi) 189 movl PTR(PA_SWAP_PAGE)(%ebp), %eax 190 movl %eax, CP_PA_SWAP_PAGE(%edi) 191 movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi) 192 193 /* get physical address of control page now */ 194 /* this is impossible after page table switch */ 195 movl PTR(PA_CONTROL_PAGE)(%ebp), %edi 196 197 /* switch to new set of page tables */ 198 movl PTR(PA_PGD)(%ebp), %eax 199 movl %eax, %cr3 200 201 /* setup a new stack at the end of the physical control page */ 202 lea PAGE_SIZE(%edi), %esp 203 204 /* jump to identity mapped page */ 205 movl %edi, %eax 206 addl $(identity_mapped - relocate_kernel), %eax 207 pushl %eax 208 ret 209 210identity_mapped: 211 /* store the start address on the stack */ 212 pushl %edx 213 214 /* Set cr0 to a known state: 215 * - Paging disabled 216 * - Alignment check disabled 217 * - Write protect disabled 218 * - No task switch 219 * - Don't do FP software emulation. 220 * - Proctected mode enabled 221 */ 222 movl %cr0, %eax 223 andl $~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax 224 orl $(X86_CR0_PE), %eax 225 movl %eax, %cr0 226 227 /* clear cr4 if applicable */ 228 testl %ecx, %ecx 229 jz 1f 230 /* Set cr4 to a known state: 231 * Setting everything to zero seems safe. 232 */ 233 xorl %eax, %eax 234 movl %eax, %cr4 235 236 jmp 1f 2371: 238 239 /* Flush the TLB (needed?) */ 240 xorl %eax, %eax 241 movl %eax, %cr3 242 243 movl CP_PA_SWAP_PAGE(%edi), %eax 244 pushl %eax 245 pushl %ebx 246 call swap_pages 247 addl $8, %esp 248 249 /* To be certain of avoiding problems with self-modifying code 250 * I need to execute a serializing instruction here. 251 * So I flush the TLB, it's handy, and not processor dependent. 252 */ 253 xorl %eax, %eax 254 movl %eax, %cr3 255 256 /* set all of the registers to known values */ 257 /* leave %esp alone */ 258 259 testl %esi, %esi 260 jnz 1f 261 xorl %edi, %edi 262 xorl %eax, %eax 263 xorl %ebx, %ebx 264 xorl %ecx, %ecx 265 xorl %edx, %edx 266 xorl %esi, %esi 267 xorl %ebp, %ebp 268 ret 2691: 270 popl %edx 271 movl CP_PA_SWAP_PAGE(%edi), %esp 272 addl $PAGE_SIZE, %esp 2732: 274 call *%edx 275 276 /* get the re-entry point of the peer system */ 277 movl 0(%esp), %ebp 278 call 1f 2791: 280 popl %ebx 281 subl $(1b - relocate_kernel), %ebx 282 movl CP_VA_CONTROL_PAGE(%ebx), %edi 283 lea PAGE_SIZE(%ebx), %esp 284 movl CP_PA_SWAP_PAGE(%ebx), %eax 285 movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx 286 pushl %eax 287 pushl %edx 288 call swap_pages 289 addl $8, %esp 290 movl CP_PA_PGD(%ebx), %eax 291 movl %eax, %cr3 292 movl %cr0, %eax 293 orl $(1<<31), %eax 294 movl %eax, %cr0 295 lea PAGE_SIZE(%edi), %esp 296 movl %edi, %eax 297 addl $(virtual_mapped - relocate_kernel), %eax 298 pushl %eax 299 ret 300 301virtual_mapped: 302 movl CR4(%edi), %eax 303 movl %eax, %cr4 304 movl CR3(%edi), %eax 305 movl %eax, %cr3 306 movl CR0(%edi), %eax 307 movl %eax, %cr0 308 movl ESP(%edi), %esp 309 movl %ebp, %eax 310 311 popf 312 popl %ebp 313 popl %edi 314 popl %esi 315 popl %ebx 316 ret 317 318 /* Do the copies */ 319swap_pages: 320 movl 8(%esp), %edx 321 movl 4(%esp), %ecx 322 pushl %ebp 323 pushl %ebx 324 pushl %edi 325 pushl %esi 326 movl %ecx, %ebx 327 jmp 1f 328 3290: /* top, read another word from the indirection page */ 330 movl (%ebx), %ecx 331 addl $4, %ebx 3321: 333 testl $0x1, %ecx /* is it a destination page */ 334 jz 2f 335 movl %ecx, %edi 336 andl $0xfffff000, %edi 337 jmp 0b 3382: 339 testl $0x2, %ecx /* is it an indirection page */ 340 jz 2f 341 movl %ecx, %ebx 342 andl $0xfffff000, %ebx 343 jmp 0b 3442: 345 testl $0x4, %ecx /* is it the done indicator */ 346 jz 2f 347 jmp 3f 3482: 349 testl $0x8, %ecx /* is it the source indicator */ 350 jz 0b /* Ignore it otherwise */ 351 movl %ecx, %esi /* For every source page do a copy */ 352 andl $0xfffff000, %esi 353 354 movl %edi, %eax 355 movl %esi, %ebp 356 357 movl %edx, %edi 358 movl $1024, %ecx 359 rep ; movsl 360 361 movl %ebp, %edi 362 movl %eax, %esi 363 movl $1024, %ecx 364 rep ; movsl 365 366 movl %eax, %edi 367 movl %edx, %esi 368 movl $1024, %ecx 369 rep ; movsl 370 371 lea PAGE_SIZE(%ebp), %esi 372 jmp 0b 3733: 374 popl %esi 375 popl %edi 376 popl %ebx 377 popl %ebp 378 ret 379