arch/x86/kernel/relocate_kernel_64.S

   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
  44 relocate_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
 102 identity_mapped:
 103         /* store the start address on the stack */
 104         pushq   %rdx
 105
 106         /*
 107          * Set cr0 to a known state:
 108          *  - Paging enabled
 109          *  - Alignment check disabled
 110          *  - Write protect disabled
 111          *  - No task switch
 112          *  - Don't do FP software emulation.
 113          *  - Proctected mode enabled
 114          */
 115         movq    %cr0, %rax
 116         andq    $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
 117         orl     $(X86_CR0_PG | X86_CR0_PE), %eax
 118         movq    %rax, %cr0
 119
 120         /*
 121          * Set cr4 to a known state:
 122          *  - physical address extension enabled
 123          */
 124         movq    $X86_CR4_PAE, %rax
 125         movq    %rax, %cr4
 126
 127         jmp 1f
 128 1:
 129
 130         /* Flush the TLB (needed?) */
 131         movq    %r9, %cr3
 132
 133         movq    %rcx, %r11
 134         call    swap_pages
 135
 136         /*
 137          * To be certain of avoiding problems with self-modifying code
 138          * I need to execute a serializing instruction here.
 139          * So I flush the TLB by reloading %cr3 here, it's handy,
 140          * and not processor dependent.
 141          */
 142         movq    %cr3, %rax
 143         movq    %rax, %cr3
 144
 145         /*
 146          * set all of the registers to known values
 147          * leave %rsp alone
 148          */
 149
 150         testq   %r11, %r11
 151         jnz 1f
 152         xorq    %rax, %rax
 153         xorq    %rbx, %rbx
 154         xorq    %rcx, %rcx
 155         xorq    %rdx, %rdx
 156         xorq    %rsi, %rsi
 157         xorq    %rdi, %rdi
 158         xorq    %rbp, %rbp
 159         xorq    %r8,  %r8
 160         xorq    %r9,  %r9
 161         xorq    %r10, %r9
 162         xorq    %r11, %r11
 163         xorq    %r12, %r12
 164         xorq    %r13, %r13
 165         xorq    %r14, %r14
 166         xorq    %r15, %r15
 167
 168         ret
 169
 170 1:
 171         popq    %rdx
 172         leaq    PAGE_SIZE(%r10), %rsp
 173         call    *%rdx
 174
 175         /* get the re-entry point of the peer system */
 176         movq    0(%rsp), %rbp
 177         call    1f
 178 1:
 179         popq    %r8
 180         subq    $(1b - relocate_kernel), %r8
 181         movq    CP_PA_SWAP_PAGE(%r8), %r10
 182         movq    CP_PA_BACKUP_PAGES_MAP(%r8), %rdi
 183         movq    CP_PA_TABLE_PAGE(%r8), %rax
 184         movq    %rax, %cr3
 185         lea     PAGE_SIZE(%r8), %rsp
 186         call    swap_pages
 187         movq    $virtual_mapped, %rax
 188         pushq   %rax
 189         ret
 190
 191 virtual_mapped:
 192         movq    RSP(%r8), %rsp
 193         movq    CR4(%r8), %rax
 194         movq    %rax, %cr4
 195         movq    CR3(%r8), %rax
 196         movq    CR0(%r8), %r8
 197         movq    %rax, %cr3
 198         movq    %r8, %cr0
 199         movq    %rbp, %rax
 200
 201         popf
 202         popq    %r15
 203         popq    %r14
 204         popq    %r13
 205         popq    %r12
 206         popq    %rbp
 207         popq    %rbx
 208         ret
 209
 210         /* Do the copies */
 211 swap_pages:
 212         movq    %rdi, %rcx      /* Put the page_list in %rcx */
 213         xorq    %rdi, %rdi
 214         xorq    %rsi, %rsi
 215         jmp     1f
 216
 217 0:      /* top, read another word for the indirection page */
 218
 219         movq    (%rbx), %rcx
 220         addq    $8,     %rbx
 221 1:
 222         testq   $0x1,   %rcx  /* is it a destination page? */
 223         jz      2f
 224         movq    %rcx,   %rdi
 225         andq    $0xfffffffffffff000, %rdi
 226         jmp     0b
 227 2:
 228         testq   $0x2,   %rcx  /* is it an indirection page? */
 229         jz      2f
 230         movq    %rcx,   %rbx
 231         andq    $0xfffffffffffff000, %rbx
 232         jmp     0b
 233 2:
 234         testq   $0x4,   %rcx  /* is it the done indicator? */
 235         jz      2f
 236         jmp     3f
 237 2:
 238         testq   $0x8,   %rcx  /* is it the source indicator? */
 239         jz      0b            /* Ignore it otherwise */
 240         movq    %rcx,   %rsi  /* For ever source page do a copy */
 241         andq    $0xfffffffffffff000, %rsi
 242
 243         movq    %rdi, %rdx
 244         movq    %rsi, %rax
 245
 246         movq    %r10, %rdi
 247         movq    $512,   %rcx
 248         rep ; movsq
 249
 250         movq    %rax, %rdi
 251         movq    %rdx, %rsi
 252         movq    $512,   %rcx
 253         rep ; movsq
 254
 255         movq    %rdx, %rdi
 256         movq    %r10, %rsi
 257         movq    $512,   %rcx
 258         rep ; movsq
 259
 260         lea     PAGE_SIZE(%rax), %rsi
 261         jmp     0b
 262 3:
 263         ret
 264
 265         .globl kexec_control_code_size
 266 .set kexec_control_code_size, . - relocate_kernel