arch/x86/purgatory/entry64.S

   1 /*
   2  * Copyright (C) 2003,2004  Eric Biederman (ebiederm@xmission.com)
   3  * Copyright (C) 2014  Red Hat Inc.
   4
   5  * Author(s): Vivek Goyal <vgoyal@redhat.com>
   6  *
   7  * This code has been taken from kexec-tools.
   8  *
   9  * This source code is licensed under the GNU General Public License,
  10  * Version 2.  See the file COPYING for more details.
  11  */
  12
  13         .text
  14         .balign 16
  15         .code64
  16         .globl entry64, entry64_regs
  17
  18
  19 entry64:
  20         /* Setup a gdt that should be preserved */
  21         lgdt gdt(%rip)
  22
  23         /* load the data segments */
  24         movl    $0x18, %eax     /* data segment */
  25         movl    %eax, %ds
  26         movl    %eax, %es
  27         movl    %eax, %ss
  28         movl    %eax, %fs
  29         movl    %eax, %gs
  30
  31         /* Setup new stack */
  32         leaq    stack_init(%rip), %rsp
  33         pushq   $0x10 /* CS */
  34         leaq    new_cs_exit(%rip), %rax
  35         pushq   %rax
  36         lretq
  37 new_cs_exit:
  38
  39         /* Load the registers */
  40         movq    rax(%rip), %rax
  41         movq    rbx(%rip), %rbx
  42         movq    rcx(%rip), %rcx
  43         movq    rdx(%rip), %rdx
  44         movq    rsi(%rip), %rsi
  45         movq    rdi(%rip), %rdi
  46         movq    rsp(%rip), %rsp
  47         movq    rbp(%rip), %rbp
  48         movq    r8(%rip), %r8
  49         movq    r9(%rip), %r9
  50         movq    r10(%rip), %r10
  51         movq    r11(%rip), %r11
  52         movq    r12(%rip), %r12
  53         movq    r13(%rip), %r13
  54         movq    r14(%rip), %r14
  55         movq    r15(%rip), %r15
  56
  57         /* Jump to the new code... */
  58         jmpq    *rip(%rip)
  59
  60         .section ".rodata"
  61         .balign 4
  62 entry64_regs:
  63 rax:    .quad 0x0
  64 rcx:    .quad 0x0
  65 rdx:    .quad 0x0
  66 rbx:    .quad 0x0
  67 rsp:    .quad 0x0
  68 rbp:    .quad 0x0
  69 rsi:    .quad 0x0
  70 rdi:    .quad 0x0
  71 r8:     .quad 0x0
  72 r9:     .quad 0x0
  73 r10:    .quad 0x0
  74 r11:    .quad 0x0
  75 r12:    .quad 0x0
  76 r13:    .quad 0x0
  77 r14:    .quad 0x0
  78 r15:    .quad 0x0
  79 rip:    .quad 0x0
  80         .size entry64_regs, . - entry64_regs
  81
  82         /* GDT */
  83         .section ".rodata"
  84         .balign 16
  85 gdt:
  86         /* 0x00 unusable segment
  87          * 0x08 unused
  88          * so use them as gdt ptr
  89          */
  90         .word gdt_end - gdt - 1
  91         .quad gdt
  92         .word 0, 0, 0
  93
  94         /* 0x10 4GB flat code segment */
  95         .word 0xFFFF, 0x0000, 0x9A00, 0x00AF
  96
  97         /* 0x18 4GB flat data segment */
  98         .word 0xFFFF, 0x0000, 0x9200, 0x00CF
  99 gdt_end:
 100 stack:  .quad   0, 0
 101 stack_init: