/* SPDX-License-Identifier: GPL-2.0-only */ /* ----------------------------------------------------------------------- * * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright 2007 rPath, Inc. - All Rights Reserved * * ----------------------------------------------------------------------- */ /* * The actual transition into protected mode */ #include <asm/boot.h> #include <asm/processor-flags.h> #include <asm/segment.h> #include <linux/linkage.h> .text .code16 /* * void protected_mode_jump(u32 entrypoint, u32 bootparams); */ SYM_FUNC_START_NOALIGN(protected_mode_jump) movl %edx, %esi # Pointer to boot_params table xorl %ebx, %ebx movw %cs, %bx shll $4, %ebx addl %ebx, 2f jmp 1f # Short jump to serialize on 386/486 1: movw $__BOOT_DS, %cx movw $__BOOT_TSS, %di movl %cr0, %edx orb $X86_CR0_PE, %dl # Protected mode movl %edx, %cr0 # Transition to 32-bit mode .byte 0x66, 0xea # ljmpl opcode 2: .long .Lin_pm32 # offset .word __BOOT_CS # segment SYM_FUNC_END(protected_mode_jump) .code32 .section ".text32","ax" SYM_FUNC_START_LOCAL_NOALIGN(.Lin_pm32) # Set up data segments for flat 32-bit mode movl %ecx, %ds movl %ecx, %es movl %ecx, %fs movl %ecx, %gs movl %ecx, %ss # The 32-bit code sets up its own stack, but this way we do have # a valid stack if some debugging hack wants to use it. addl %ebx, %esp # Set up TR to make Intel VT happy ltr %di # Clear registers to allow for future extensions to the # 32-bit boot protocol xorl %ecx, %ecx xorl %edx, %edx xorl %ebx, %ebx xorl %ebp, %ebp xorl %edi, %edi # Set up LDTR to make Intel VT happy lldt %cx jmpl *%eax # Jump to the 32-bit entrypoint SYM_FUNC_END(.Lin_pm32)
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