1/* ----------------------------------------------------------------------- *
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/*
12 * The actual transition into protected mode
13 */
14
15#include <asm/boot.h>
16#include <asm/processor-flags.h>
17#include <asm/segment.h>
18#include <linux/linkage.h>
19
20 .text
21 .code16
22
23/*
24 * void protected_mode_jump(u32 entrypoint, u32 bootparams);
25 */
26GLOBAL(protected_mode_jump)
27 movl %edx, %esi # Pointer to boot_params table
28
29 xorl %ebx, %ebx
30 movw %cs, %bx
31 shll $4, %ebx
32 addl %ebx, 2f
33 jmp 1f # Short jump to serialize on 386/486
341:
35
36 movw $__BOOT_DS, %cx
37 movw $__BOOT_TSS, %di
38
39 movl %cr0, %edx
40 orb $X86_CR0_PE, %dl # Protected mode
41 movl %edx, %cr0
42
43 # Transition to 32-bit mode
44 .byte 0x66, 0xea # ljmpl opcode
452: .long in_pm32 # offset
46 .word __BOOT_CS # segment
47ENDPROC(protected_mode_jump)
48
49 .code32
50 .section ".text32","ax"
51GLOBAL(in_pm32)
52 # Set up data segments for flat 32-bit mode
53 movl %ecx, %ds
54 movl %ecx, %es
55 movl %ecx, %fs
56 movl %ecx, %gs
57 movl %ecx, %ss
58 # The 32-bit code sets up its own stack, but this way we do have
59 # a valid stack if some debugging hack wants to use it.
60 addl %ebx, %esp
61
62 # Set up TR to make Intel VT happy
63 ltr %di
64
65 # Clear registers to allow for future extensions to the
66 # 32-bit boot protocol
67 xorl %ecx, %ecx
68 xorl %edx, %edx
69 xorl %ebx, %ebx
70 xorl %ebp, %ebp
71 xorl %edi, %edi
72
73 # Set up LDTR to make Intel VT happy
74 lldt %cx
75
76 jmpl *%eax # Jump to the 32-bit entrypoint
77ENDPROC(in_pm32)
78