1*8cfc966cSSimon Glass/* 2*8cfc966cSSimon Glass * (C) Copyright 2014 Google, Inc 3*8cfc966cSSimon Glass * Copyright (C) 1991, 1992, 1993 Linus Torvalds 4*8cfc966cSSimon Glass * 5*8cfc966cSSimon Glass * Parts of this copied from Linux arch/x86/boot/compressed/head_64.S 6*8cfc966cSSimon Glass * 7*8cfc966cSSimon Glass * SPDX-License-Identifier: GPL-2.0+ 8*8cfc966cSSimon Glass */ 9*8cfc966cSSimon Glass 10*8cfc966cSSimon Glass#include <asm/global_data.h> 11*8cfc966cSSimon Glass#include <asm/msr-index.h> 12*8cfc966cSSimon Glass#include <asm/processor-flags.h> 13*8cfc966cSSimon Glass 14*8cfc966cSSimon Glass.code32 15*8cfc966cSSimon Glass.globl cpu_call64 16*8cfc966cSSimon Glasscpu_call64: 17*8cfc966cSSimon Glass /* 18*8cfc966cSSimon Glass * cpu_call64(ulong pgtable, ulong setup_base, ulong target) 19*8cfc966cSSimon Glass * 20*8cfc966cSSimon Glass * eax - pgtable 21*8cfc966cSSimon Glass * edx - setup_base 22*8cfc966cSSimon Glass * ecx - target 23*8cfc966cSSimon Glass */ 24*8cfc966cSSimon Glass cli 25*8cfc966cSSimon Glass push %ecx /* arg2 = target */ 26*8cfc966cSSimon Glass push %edx /* arg1 = setup_base */ 27*8cfc966cSSimon Glass mov %eax, %ebx 28*8cfc966cSSimon Glass 29*8cfc966cSSimon Glass /* Load new GDT with the 64bit segments using 32bit descriptor */ 30*8cfc966cSSimon Glass leal gdt, %eax 31*8cfc966cSSimon Glass movl %eax, gdt+2 32*8cfc966cSSimon Glass lgdt gdt 33*8cfc966cSSimon Glass 34*8cfc966cSSimon Glass /* Enable PAE mode */ 35*8cfc966cSSimon Glass movl $(X86_CR4_PAE), %eax 36*8cfc966cSSimon Glass movl %eax, %cr4 37*8cfc966cSSimon Glass 38*8cfc966cSSimon Glass /* Enable the boot page tables */ 39*8cfc966cSSimon Glass leal (%ebx), %eax 40*8cfc966cSSimon Glass movl %eax, %cr3 41*8cfc966cSSimon Glass 42*8cfc966cSSimon Glass /* Enable Long mode in EFER (Extended Feature Enable Register) */ 43*8cfc966cSSimon Glass movl $MSR_EFER, %ecx 44*8cfc966cSSimon Glass rdmsr 45*8cfc966cSSimon Glass btsl $_EFER_LME, %eax 46*8cfc966cSSimon Glass wrmsr 47*8cfc966cSSimon Glass 48*8cfc966cSSimon Glass /* After gdt is loaded */ 49*8cfc966cSSimon Glass xorl %eax, %eax 50*8cfc966cSSimon Glass lldt %ax 51*8cfc966cSSimon Glass movl $0x20, %eax 52*8cfc966cSSimon Glass ltr %ax 53*8cfc966cSSimon Glass 54*8cfc966cSSimon Glass /* 55*8cfc966cSSimon Glass * Setup for the jump to 64bit mode 56*8cfc966cSSimon Glass * 57*8cfc966cSSimon Glass * When the jump is performed we will be in long mode but 58*8cfc966cSSimon Glass * in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1 59*8cfc966cSSimon Glass * (and in turn EFER.LMA = 1). To jump into 64bit mode we use 60*8cfc966cSSimon Glass * the new gdt/idt that has __KERNEL_CS with CS.L = 1. 61*8cfc966cSSimon Glass * We place all of the values on our mini stack so lret can 62*8cfc966cSSimon Glass * used to perform that far jump. See the gdt below. 63*8cfc966cSSimon Glass */ 64*8cfc966cSSimon Glass pop %esi /* setup_base */ 65*8cfc966cSSimon Glass 66*8cfc966cSSimon Glass pushl $0x10 67*8cfc966cSSimon Glass leal lret_target, %eax 68*8cfc966cSSimon Glass pushl %eax 69*8cfc966cSSimon Glass 70*8cfc966cSSimon Glass /* Enter paged protected Mode, activating Long Mode */ 71*8cfc966cSSimon Glass movl $(X86_CR0_PG | X86_CR0_PE), %eax 72*8cfc966cSSimon Glass movl %eax, %cr0 73*8cfc966cSSimon Glass 74*8cfc966cSSimon Glass /* Jump from 32bit compatibility mode into 64bit mode. */ 75*8cfc966cSSimon Glass lret 76*8cfc966cSSimon Glass 77*8cfc966cSSimon Glasscode64: 78*8cfc966cSSimon Glasslret_target: 79*8cfc966cSSimon Glass pop %eax /* target */ 80*8cfc966cSSimon Glass mov %eax, %eax /* Clear bits 63:32 */ 81*8cfc966cSSimon Glass jmp *%eax /* Jump to the 64-bit target */ 82*8cfc966cSSimon Glass 83*8cfc966cSSimon Glass .data 84*8cfc966cSSimon Glass .align 16 85*8cfc966cSSimon Glass .globl gdt64 86*8cfc966cSSimon Glassgdt64: 87*8cfc966cSSimon Glassgdt: 88*8cfc966cSSimon Glass .word gdt_end - gdt - 1 89*8cfc966cSSimon Glass .long gdt /* Fixed up by code above */ 90*8cfc966cSSimon Glass .word 0 91*8cfc966cSSimon Glass .quad 0x0000000000000000 /* NULL descriptor */ 92*8cfc966cSSimon Glass .quad 0x00af9a000000ffff /* __KERNEL_CS */ 93*8cfc966cSSimon Glass .quad 0x00cf92000000ffff /* __KERNEL_DS */ 94*8cfc966cSSimon Glass .quad 0x0080890000000000 /* TS descriptor */ 95*8cfc966cSSimon Glass .quad 0x0000000000000000 /* TS continued */ 96*8cfc966cSSimon Glassgdt_end: 97