1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* ----------------------------------------------------------------------- * 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * Copyright 2007 rPath, Inc. - All Rights Reserved 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, u32 bootparams); 23 */ 24SYM_FUNC_START_NOALIGN(protected_mode_jump) 25 movl %edx, %esi # Pointer to boot_params table 26 27 xorl %ebx, %ebx 28 movw %cs, %bx 29 shll $4, %ebx 30 addl %ebx, 2f 31 jmp 1f # Short jump to serialize on 386/486 321: 33 34 movw $__BOOT_DS, %cx 35 movw $__BOOT_TSS, %di 36 37 movl %cr0, %edx 38 orb $X86_CR0_PE, %dl # Protected mode 39 movl %edx, %cr0 40 41 # Transition to 32-bit mode 42 .byte 0x66, 0xea # ljmpl opcode 432: .long .Lin_pm32 # offset 44 .word __BOOT_CS # segment 45SYM_FUNC_END(protected_mode_jump) 46 47 .code32 48 .section ".text32","ax" 49SYM_FUNC_START_LOCAL_NOALIGN(.Lin_pm32) 50 # Set up data segments for flat 32-bit mode 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 stack, but this way we do have 57 # a valid stack if some debugging hack wants to use it. 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 extensions to the 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 to the 32-bit entrypoint 75SYM_FUNC_END(.Lin_pm32) 76