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         .text
  23         .align PAGE_SIZE
  24         .code64
  25         .globl relocate_kernel
  26 relocate_kernel:
  27         /* %rdi indirection_page
  28          * %rsi page_list
  29          * %rdx start address
  30          */
  31
  32         /* zero out flags, and disable interrupts */
  33         pushq $0
  34         popfq
  35
  36         /* get physical address of control page now */
  37         /* this is impossible after page table switch */
  38         movq    PTR(PA_CONTROL_PAGE)(%rsi), %r8
  39
  40         /* get physical address of page table now too */
  41         movq    PTR(PA_TABLE_PAGE)(%rsi), %rcx
  42
  43         /* Switch to the identity mapped page tables */
  44         movq    %rcx, %cr3
  45
  46         /* setup a new stack at the end of the physical control page */
  47         lea     PAGE_SIZE(%r8), %rsp
  48
  49         /* jump to identity mapped page */
  50         addq    $(identity_mapped - relocate_kernel), %r8
  51         pushq   %r8
  52         ret
  53
  54 identity_mapped:
  55         /* store the start address on the stack */
  56         pushq   %rdx
  57
  58         /* Set cr0 to a known state:
  59          *  - Paging enabled
  60          *  - Alignment check disabled
  61          *  - Write protect disabled
  62          *  - No task switch
  63          *  - Don't do FP software emulation.
  64          *  - Proctected mode enabled
  65          */
  66         movq    %cr0, %rax
  67         andq    $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
  68         orl     $(X86_CR0_PG | X86_CR0_PE), %eax
  69         movq    %rax, %cr0
  70
  71         /* Set cr4 to a known state:
  72          *  - physical address extension enabled
  73          */
  74         movq    $X86_CR4_PAE, %rax
  75         movq    %rax, %cr4
  76
  77         jmp 1f
  78 1:
  79
  80         /* Flush the TLB (needed?) */
  81         movq    %rcx, %cr3
  82
  83         /* Do the copies */
  84         movq    %rdi, %rcx      /* Put the page_list in %rcx */
  85         xorq    %rdi, %rdi
  86         xorq    %rsi, %rsi
  87         jmp     1f
  88
  89 0:      /* top, read another word for the indirection page */
  90
  91         movq    (%rbx), %rcx
  92         addq    $8,     %rbx
  93 1:
  94         testq   $0x1,   %rcx  /* is it a destination page? */
  95         jz      2f
  96         movq    %rcx,   %rdi
  97         andq    $0xfffffffffffff000, %rdi
  98         jmp     0b
  99 2:
 100         testq   $0x2,   %rcx  /* is it an indirection page? */
 101         jz      2f
 102         movq    %rcx,   %rbx
 103         andq    $0xfffffffffffff000, %rbx
 104         jmp     0b
 105 2:
 106         testq   $0x4,   %rcx  /* is it the done indicator? */
 107         jz      2f
 108         jmp     3f
 109 2:
 110         testq   $0x8,   %rcx  /* is it the source indicator? */
 111         jz      0b            /* Ignore it otherwise */
 112         movq    %rcx,   %rsi  /* For ever source page do a copy */
 113         andq    $0xfffffffffffff000, %rsi
 114
 115         movq    $512,   %rcx
 116         rep ; movsq
 117         jmp     0b
 118 3:
 119
 120         /* To be certain of avoiding problems with self-modifying code
 121          * I need to execute a serializing instruction here.
 122          * So I flush the TLB by reloading %cr3 here, it's handy,
 123          * and not processor dependent.
 124          */
 125         movq    %cr3, %rax
 126         movq    %rax, %cr3
 127
 128         /* set all of the registers to known values */
 129         /* leave %rsp alone */
 130
 131         xorq    %rax, %rax
 132         xorq    %rbx, %rbx
 133         xorq    %rcx, %rcx
 134         xorq    %rdx, %rdx
 135         xorq    %rsi, %rsi
 136         xorq    %rdi, %rdi
 137         xorq    %rbp, %rbp
 138         xorq    %r8,  %r8
 139         xorq    %r9,  %r9
 140         xorq    %r10, %r9
 141         xorq    %r11, %r11
 142         xorq    %r12, %r12
 143         xorq    %r13, %r13
 144         xorq    %r14, %r14
 145         xorq    %r15, %r15
 146
 147         ret