/*
|
* (C) Copyright 2014 Google, Inc
|
* Copyright (C) 1991, 1992, 1993 Linus Torvalds
|
*
|
* Parts of this copied from Linux arch/x86/boot/compressed/head_64.S
|
*
|
* SPDX-License-Identifier: GPL-2.0+
|
*/
|
|
#include <asm/global_data.h>
|
#include <asm/msr-index.h>
|
#include <asm/processor-flags.h>
|
|
.code32
|
.globl cpu_call64
|
cpu_call64:
|
/*
|
* cpu_call64(ulong pgtable, ulong setup_base, ulong target)
|
*
|
* eax - pgtable
|
* edx - setup_base
|
* ecx - target
|
*/
|
cli
|
push %ecx /* arg2 = target */
|
push %edx /* arg1 = setup_base */
|
mov %eax, %ebx
|
|
/* Load new GDT with the 64bit segments using 32bit descriptor */
|
leal gdt, %eax
|
movl %eax, gdt+2
|
lgdt gdt
|
|
/* Enable PAE mode */
|
movl $(X86_CR4_PAE), %eax
|
movl %eax, %cr4
|
|
/* Enable the boot page tables */
|
leal (%ebx), %eax
|
movl %eax, %cr3
|
|
/* Enable Long mode in EFER (Extended Feature Enable Register) */
|
movl $MSR_EFER, %ecx
|
rdmsr
|
btsl $_EFER_LME, %eax
|
wrmsr
|
|
/* After gdt is loaded */
|
xorl %eax, %eax
|
lldt %ax
|
movl $0x20, %eax
|
ltr %ax
|
|
/*
|
* Setup for the jump to 64bit mode
|
*
|
* When the jump is performed we will be in long mode but
|
* in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1
|
* (and in turn EFER.LMA = 1). To jump into 64bit mode we use
|
* the new gdt/idt that has __KERNEL_CS with CS.L = 1.
|
* We place all of the values on our mini stack so lret can
|
* used to perform that far jump. See the gdt below.
|
*/
|
pop %esi /* setup_base */
|
|
pushl $0x10
|
leal lret_target, %eax
|
pushl %eax
|
|
/* Enter paged protected Mode, activating Long Mode */
|
movl $(X86_CR0_PG | X86_CR0_PE), %eax
|
movl %eax, %cr0
|
|
/* Jump from 32bit compatibility mode into 64bit mode. */
|
lret
|
|
code64:
|
lret_target:
|
pop %eax /* target */
|
mov %eax, %eax /* Clear bits 63:32 */
|
jmp *%eax /* Jump to the 64-bit target */
|
|
.data
|
.align 16
|
.globl gdt64
|
gdt64:
|
gdt:
|
.word gdt_end - gdt - 1
|
.long gdt /* Fixed up by code above */
|
.word 0
|
.quad 0x0000000000000000 /* NULL descriptor */
|
.quad 0x00af9a000000ffff /* __KERNEL_CS */
|
.quad 0x00cf92000000ffff /* __KERNEL_DS */
|
.quad 0x0080890000000000 /* TS descriptor */
|
.quad 0x0000000000000000 /* TS continued */
|
gdt_end:
|
