1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /* -------------------------------------------
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright 2007 rPath, Inc. - All Rights R
6 *
7 * -------------------------------------------
8
9 /*
10 * The actual transition into protected mode
11 */
12
13 #include <asm/boot.h>
14 #include <asm/processor-flags.h>
15 #include <asm/segment.h>
16 #include <linux/linkage.h>
17
18 .text
19 .code16
20
21 /*
22 * void protected_mode_jump(u32 entrypoint, u3
23 */
24 SYM_FUNC_START_NOALIGN(protected_mode_jump)
25 movl %edx, %esi # Poin
26
27 xorl %ebx, %ebx
28 movw %cs, %bx
29 shll $4, %ebx
30 addl %ebx, 2f
31 jmp 1f # Shor
32 1:
33
34 movw $__BOOT_DS, %cx
35 movw $__BOOT_TSS, %di
36
37 movl %cr0, %edx
38 orb $X86_CR0_PE, %dl # Prot
39 movl %edx, %cr0
40
41 # Transition to 32-bit mode
42 .byte 0x66, 0xea # ljmp
43 2: .long .Lin_pm32 # offs
44 .word __BOOT_CS # segm
45 SYM_FUNC_END(protected_mode_jump)
46
47 .code32
48 .section ".text32","ax"
49 SYM_FUNC_START_LOCAL_NOALIGN(.Lin_pm32)
50 # Set up data segments for flat 32-bit
51 movl %ecx, %ds
52 movl %ecx, %es
53 movl %ecx, %fs
54 movl %ecx, %gs
55 movl %ecx, %ss
56 # The 32-bit code sets up its own stac
57 # a valid stack if some debugging hack
58 addl %ebx, %esp
59
60 # Set up TR to make Intel VT happy
61 ltr %di
62
63 # Clear registers to allow for future
64 # 32-bit boot protocol
65 xorl %ecx, %ecx
66 xorl %edx, %edx
67 xorl %ebx, %ebx
68 xorl %ebp, %ebp
69 xorl %edi, %edi
70
71 # Set up LDTR to make Intel VT happy
72 lldt %cx
73
74 jmpl *%eax # Jump
75 SYM_FUNC_END(.Lin_pm32)
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