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H. Peter Anvin7052fdd2007-07-11 12:18:53 -07001/* ----------------------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 *
6 * This file is part of the Linux kernel, and is made available under
7 * the terms of the GNU General Public License version 2.
8 *
9 * ----------------------------------------------------------------------- */
10
11/*
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070012 * The actual transition into protected mode
13 */
14
15#include <asm/boot.h>
H. Peter Anvin02a7b422008-01-30 13:33:02 +010016#include <asm/processor-flags.h>
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070017#include <asm/segment.h>
18
19 .text
20
21 .globl protected_mode_jump
22 .type protected_mode_jump, @function
23
24 .code16
25
26/*
27 * void protected_mode_jump(u32 entrypoint, u32 bootparams);
28 */
29protected_mode_jump:
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070030 movl %edx, %esi # Pointer to boot_params table
H. Peter Anvinc4d9ba62008-01-30 13:33:01 +010031
32 xorl %ebx, %ebx
33 movw %cs, %bx
34 shll $4, %ebx
35 addl %ebx, 2f
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070036
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070037 movw $__BOOT_DS, %cx
H. Peter Anvin88089512008-01-30 13:33:02 +010038 movw $__BOOT_TSS, %di
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070039
40 movl %cr0, %edx
H. Peter Anvin02a7b422008-01-30 13:33:02 +010041 orb $X86_CR0_PE, %dl # Protected mode
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070042 movl %edx, %cr0
H. Peter Anvin7ed19292007-11-04 17:50:12 -080043 jmp 1f # Short jump to serialize on 386/486
441:
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070045
H. Peter Anvinc4d9ba62008-01-30 13:33:01 +010046 # Transition to 32-bit mode
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070047 .byte 0x66, 0xea # ljmpl opcode
H. Peter Anvinc4d9ba62008-01-30 13:33:01 +0100482: .long in_pm32 # offset
H. Peter Anvin7052fdd2007-07-11 12:18:53 -070049 .word __BOOT_CS # segment
50
51 .size protected_mode_jump, .-protected_mode_jump
H. Peter Anvinc4d9ba62008-01-30 13:33:01 +010052
53 .code32
54 .type in_pm32, @function
55in_pm32:
56 # Set up data segments for flat 32-bit mode
57 movl %ecx, %ds
58 movl %ecx, %es
59 movl %ecx, %fs
60 movl %ecx, %gs
61 movl %ecx, %ss
62 # The 32-bit code sets up its own stack, but this way we do have
63 # a valid stack if some debugging hack wants to use it.
64 addl %ebx, %esp
65
H. Peter Anvin88089512008-01-30 13:33:02 +010066 # Set up TR to make Intel VT happy
67 ltr %di
68
H. Peter Anvinc4d9ba62008-01-30 13:33:01 +010069 # Clear registers to allow for future extensions to the
70 # 32-bit boot protocol
71 xorl %ecx, %ecx
72 xorl %edx, %edx
73 xorl %ebx, %ebx
74 xorl %ebp, %ebp
75 xorl %edi, %edi
76
H. Peter Anvin88089512008-01-30 13:33:02 +010077 # Set up LDTR to make Intel VT happy
78 lldt %cx
79
H. Peter Anvinc4d9ba62008-01-30 13:33:01 +010080 jmpl *%eax # Jump to the 32-bit entrypoint
81
82 .size in_pm32, .-in_pm32