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 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: 30 movl %edx, %esi # Pointer to boot_params table 31 32 xorl %ebx, %ebx 33 movw %cs, %bx 34 shll $4, %ebx 35 addl %ebx, 2f 36 jmp 1f # Short jump to serialize on 386/486 371: 38 39 movw $__BOOT_DS, %cx 40 movw $__BOOT_TSS, %di 41 42 movl %cr0, %edx 43 orb $X86_CR0_PE, %dl # Protected mode 44 movl %edx, %cr0 45 46 # Transition to 32-bit mode 47 .byte 0x66, 0xea # ljmpl opcode 482: .long in_pm32 # offset 49 .word __BOOT_CS # segment 50 51 .size protected_mode_jump, .-protected_mode_jump 52 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 66 # Set up TR to make Intel VT happy 67 ltr %di 68 69 # 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 77 # Set up LDTR to make Intel VT happy 78 lldt %cx 79 80 jmpl *%eax # Jump to the 32-bit entrypoint 81 82 .size in_pm32, .-in_pm32 83