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| 1 /* |
| 2 * GRUB -- GRand Unified Bootloader |
| 3 * Copyright (C) 2009 Free Software Foundation, Inc. |
| 4 * |
| 5 * GRUB is free software: you can redistribute it and/or modify |
| 6 * it under the terms of the GNU General Public License as published by |
| 7 * the Free Software Foundation, either version 3 of the License, or |
| 8 * (at your option) any later version. |
| 9 * |
| 10 * GRUB is distributed in the hope that it will be useful, |
| 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 * GNU General Public License for more details. |
| 14 * |
| 15 * You should have received a copy of the GNU General Public License |
| 16 * along with GRUB. If not, see <http://www.gnu.org/licenses/>. |
| 17 */ |
| 18 |
| 19 |
| 20 .p2align 4 /* force 16-byte alignment */ |
| 21 .globl trampoline |
| 22 trampoline: |
| 23 cli |
| 24 /* %rdi contains protected memory start and %rsi |
| 25 contains real memory start. */ |
| 26 |
| 27 mov %rsi, %rbx |
| 28 |
| 29 call base |
| 30 base: |
| 31 pop %rsi |
| 32 |
| 33 lea (cont1 - base) (%rsi, 1), %rax |
| 34 mov %eax, (jump_vector - base) (%rsi, 1) |
| 35 |
| 36 lea (gdt - base) (%rsi, 1), %rax |
| 37 mov %rax, (gdtaddr - base) (%rsi, 1) |
| 38 |
| 39 /* Switch to compatibility mode. */ |
| 40 |
| 41 lidt (idtdesc - base) (%rsi, 1) |
| 42 lgdt (gdtdesc - base) (%rsi, 1) |
| 43 |
| 44 /* Update %cs. Thanks to David Miller for pointing this mistake out. */ |
| 45 ljmp *(jump_vector - base) (%rsi, 1) |
| 46 |
| 47 cont1: |
| 48 .code32 |
| 49 |
| 50 /* Update other registers. */ |
| 51 mov $0x18, %eax |
| 52 mov %eax, %ds |
| 53 mov %eax, %es |
| 54 mov %eax, %fs |
| 55 mov %eax, %gs |
| 56 mov %eax, %ss |
| 57 |
| 58 /* Disable paging. */ |
| 59 mov %cr0, %eax |
| 60 and $0x7fffffff, %eax |
| 61 mov %eax, %cr0 |
| 62 |
| 63 /* Disable amd64. */ |
| 64 mov $0xc0000080, %ecx |
| 65 rdmsr |
| 66 and $0xfffffeff, %eax |
| 67 wrmsr |
| 68 |
| 69 /* Turn off PAE. */ |
| 70 movl %cr4, %eax |
| 71 and $0xffffffcf, %eax |
| 72 mov %eax, %cr4 |
| 73 |
| 74 jmp cont2 |
| 75 cont2: |
| 76 .code32 |
| 77 |
| 78 mov %ebx, %esi |
| 79 |
| 80 jmp *%edi |
| 81 |
| 82 /* GDT. */ |
| 83 .p2align 4 |
| 84 gdt: |
| 85 /* NULL. */ |
| 86 .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 |
| 87 |
| 88 /* Reserved. */ |
| 89 .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 |
| 90 |
| 91 /* Code segment. */ |
| 92 .byte 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x9A, 0xCF, 0x00 |
| 93 |
| 94 /* Data segment. */ |
| 95 .byte 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x92, 0xCF, 0x00 |
| 96 |
| 97 gdtdesc: |
| 98 .word 31 |
| 99 gdtaddr: |
| 100 .quad gdt |
| 101 |
| 102 idtdesc: |
| 103 .word 0 |
| 104 idtaddr: |
| 105 .quad 0 |
| 106 |
| 107 .p2align 4 |
| 108 jump_vector: |
| 109 /* Jump location. Is filled by the code */ |
| 110 .long 0 |
| 111 .long 0x10 |
| 112 |
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