linux/arch/x86/kernel/relocate_kernel_64.S
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   1/*
   2 * relocate_kernel.S - put the kernel image in place to boot
   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/linkage.h>
  10#include <asm/page_types.h>
  11#include <asm/kexec.h>
  12#include <asm/processor-flags.h>
  13#include <asm/pgtable_types.h>
  14
  15/*
  16 * Must be relocatable PIC code callable as a C function
  17 */
  18
  19#define PTR(x) (x << 3)
  20#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
  21
  22/*
  23 * control_page + KEXEC_CONTROL_CODE_MAX_SIZE
  24 * ~ control_page + PAGE_SIZE are used as data storage and stack for
  25 * jumping back
  26 */
  27#define DATA(offset)            (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
  28
  29/* Minimal CPU state */
  30#define RSP                     DATA(0x0)
  31#define CR0                     DATA(0x8)
  32#define CR3                     DATA(0x10)
  33#define CR4                     DATA(0x18)
  34
  35/* other data */
  36#define CP_PA_TABLE_PAGE        DATA(0x20)
  37#define CP_PA_SWAP_PAGE         DATA(0x28)
  38#define CP_PA_BACKUP_PAGES_MAP  DATA(0x30)
  39
  40        .text
  41        .align PAGE_SIZE
  42        .code64
  43        .globl relocate_kernel
  44relocate_kernel:
  45        /*
  46         * %rdi indirection_page
  47         * %rsi page_list
  48         * %rdx start address
  49         * %rcx preserve_context
  50         */
  51
  52        /* Save the CPU context, used for jumping back */
  53        pushq %rbx
  54        pushq %rbp
  55        pushq %r12
  56        pushq %r13
  57        pushq %r14
  58        pushq %r15
  59        pushf
  60
  61        movq    PTR(VA_CONTROL_PAGE)(%rsi), %r11
  62        movq    %rsp, RSP(%r11)
  63        movq    %cr0, %rax
  64        movq    %rax, CR0(%r11)
  65        movq    %cr3, %rax
  66        movq    %rax, CR3(%r11)
  67        movq    %cr4, %rax
  68        movq    %rax, CR4(%r11)
  69
  70        /* zero out flags, and disable interrupts */
  71        pushq $0
  72        popfq
  73
  74        /*
  75         * get physical address of control page now
  76         * this is impossible after page table switch
  77         */
  78        movq    PTR(PA_CONTROL_PAGE)(%rsi), %r8
  79
  80        /* get physical address of page table now too */
  81        movq    PTR(PA_TABLE_PAGE)(%rsi), %r9
  82
  83        /* get physical address of swap page now */
  84        movq    PTR(PA_SWAP_PAGE)(%rsi), %r10
  85
  86        /* save some information for jumping back */
  87        movq    %r9, CP_PA_TABLE_PAGE(%r11)
  88        movq    %r10, CP_PA_SWAP_PAGE(%r11)
  89        movq    %rdi, CP_PA_BACKUP_PAGES_MAP(%r11)
  90
  91        /* Switch to the identity mapped page tables */
  92        movq    %r9, %cr3
  93
  94        /* setup a new stack at the end of the physical control page */
  95        lea     PAGE_SIZE(%r8), %rsp
  96
  97        /* jump to identity mapped page */
  98        addq    $(identity_mapped - relocate_kernel), %r8
  99        pushq   %r8
 100        ret
 101
 102identity_mapped:
 103        /* set return address to 0 if not preserving context */
 104        pushq   $0
 105        /* store the start address on the stack */
 106        pushq   %rdx
 107
 108        /*
 109         * Set cr0 to a known state:
 110         *  - Paging enabled
 111         *  - Alignment check disabled
 112         *  - Write protect disabled
 113         *  - No task switch
 114         *  - Don't do FP software emulation.
 115         *  - Proctected mode enabled
 116         */
 117        movq    %cr0, %rax
 118        andq    $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
 119        orl     $(X86_CR0_PG | X86_CR0_PE), %eax
 120        movq    %rax, %cr0
 121
 122        /*
 123         * Set cr4 to a known state:
 124         *  - physical address extension enabled
 125         */
 126        movq    $X86_CR4_PAE, %rax
 127        movq    %rax, %cr4
 128
 129        jmp 1f
 1301:
 131
 132        /* Flush the TLB (needed?) */
 133        movq    %r9, %cr3
 134
 135        movq    %rcx, %r11
 136        call    swap_pages
 137
 138        /*
 139         * To be certain of avoiding problems with self-modifying code
 140         * I need to execute a serializing instruction here.
 141         * So I flush the TLB by reloading %cr3 here, it's handy,
 142         * and not processor dependent.
 143         */
 144        movq    %cr3, %rax
 145        movq    %rax, %cr3
 146
 147        /*
 148         * set all of the registers to known values
 149         * leave %rsp alone
 150         */
 151
 152        testq   %r11, %r11
 153        jnz 1f
 154        xorq    %rax, %rax
 155        xorq    %rbx, %rbx
 156        xorq    %rcx, %rcx
 157        xorq    %rdx, %rdx
 158        xorq    %rsi, %rsi
 159        xorq    %rdi, %rdi
 160        xorq    %rbp, %rbp
 161        xorq    %r8,  %r8
 162        xorq    %r9,  %r9
 163        xorq    %r10, %r9
 164        xorq    %r11, %r11
 165        xorq    %r12, %r12
 166        xorq    %r13, %r13
 167        xorq    %r14, %r14
 168        xorq    %r15, %r15
 169
 170        ret
 171
 1721:
 173        popq    %rdx
 174        leaq    PAGE_SIZE(%r10), %rsp
 175        call    *%rdx
 176
 177        /* get the re-entry point of the peer system */
 178        movq    0(%rsp), %rbp
 179        call    1f
 1801:
 181        popq    %r8
 182        subq    $(1b - relocate_kernel), %r8
 183        movq    CP_PA_SWAP_PAGE(%r8), %r10
 184        movq    CP_PA_BACKUP_PAGES_MAP(%r8), %rdi
 185        movq    CP_PA_TABLE_PAGE(%r8), %rax
 186        movq    %rax, %cr3
 187        lea     PAGE_SIZE(%r8), %rsp
 188        call    swap_pages
 189        movq    $virtual_mapped, %rax
 190        pushq   %rax
 191        ret
 192
 193virtual_mapped:
 194        movq    RSP(%r8), %rsp
 195        movq    CR4(%r8), %rax
 196        movq    %rax, %cr4
 197        movq    CR3(%r8), %rax
 198        movq    CR0(%r8), %r8
 199        movq    %rax, %cr3
 200        movq    %r8, %cr0
 201        movq    %rbp, %rax
 202
 203        popf
 204        popq    %r15
 205        popq    %r14
 206        popq    %r13
 207        popq    %r12
 208        popq    %rbp
 209        popq    %rbx
 210        ret
 211
 212        /* Do the copies */
 213swap_pages:
 214        movq    %rdi, %rcx      /* Put the page_list in %rcx */
 215        xorq    %rdi, %rdi
 216        xorq    %rsi, %rsi
 217        jmp     1f
 218
 2190:      /* top, read another word for the indirection page */
 220
 221        movq    (%rbx), %rcx
 222        addq    $8,     %rbx
 2231:
 224        testq   $0x1,   %rcx  /* is it a destination page? */
 225        jz      2f
 226        movq    %rcx,   %rdi
 227        andq    $0xfffffffffffff000, %rdi
 228        jmp     0b
 2292:
 230        testq   $0x2,   %rcx  /* is it an indirection page? */
 231        jz      2f
 232        movq    %rcx,   %rbx
 233        andq    $0xfffffffffffff000, %rbx
 234        jmp     0b
 2352:
 236        testq   $0x4,   %rcx  /* is it the done indicator? */
 237        jz      2f
 238        jmp     3f
 2392:
 240        testq   $0x8,   %rcx  /* is it the source indicator? */
 241        jz      0b            /* Ignore it otherwise */
 242        movq    %rcx,   %rsi  /* For ever source page do a copy */
 243        andq    $0xfffffffffffff000, %rsi
 244
 245        movq    %rdi, %rdx
 246        movq    %rsi, %rax
 247
 248        movq    %r10, %rdi
 249        movq    $512,   %rcx
 250        rep ; movsq
 251
 252        movq    %rax, %rdi
 253        movq    %rdx, %rsi
 254        movq    $512,   %rcx
 255        rep ; movsq
 256
 257        movq    %rdx, %rdi
 258        movq    %r10, %rsi
 259        movq    $512,   %rcx
 260        rep ; movsq
 261
 262        lea     PAGE_SIZE(%rax), %rsi
 263        jmp     0b
 2643:
 265        ret
 266
 267        .globl kexec_control_code_size
 268.set kexec_control_code_size, . - relocate_kernel
 269
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