1*6f92ed8fSSimon Glass/* 2*6f92ed8fSSimon Glass * (C) Copyright 2015 Google, Inc 3*6f92ed8fSSimon Glass * Written by Simon Glass <sjg@chromium.org> 4*6f92ed8fSSimon Glass * 5*6f92ed8fSSimon Glass * SPDX-License-Identifier: GPL-2.0+ 6*6f92ed8fSSimon Glass */ 7*6f92ed8fSSimon Glass 8*6f92ed8fSSimon Glass#include <asm/global_data.h> 9*6f92ed8fSSimon Glass#include <asm/msr-index.h> 10*6f92ed8fSSimon Glass#include <asm/processor-flags.h> 11*6f92ed8fSSimon Glass 12*6f92ed8fSSimon Glass /* 13*6f92ed8fSSimon Glass * rdi - 32-bit code segment selector 14*6f92ed8fSSimon Glass * rsi - target address 15*6f92ed8fSSimon Glass * rdx - table address (0 if none) 16*6f92ed8fSSimon Glass */ 17*6f92ed8fSSimon Glass.code64 18*6f92ed8fSSimon Glass.globl cpu_call32 19*6f92ed8fSSimon Glasscpu_call32: 20*6f92ed8fSSimon Glass cli 21*6f92ed8fSSimon Glass 22*6f92ed8fSSimon Glass /* Save table pointer */ 23*6f92ed8fSSimon Glass mov %edx, %ebx 24*6f92ed8fSSimon Glass 25*6f92ed8fSSimon Glass /* 26*6f92ed8fSSimon Glass * Debugging option, this outputs characters to the console UART 27*6f92ed8fSSimon Glass * mov $0x3f8,%edx 28*6f92ed8fSSimon Glass * mov $'a',%al 29*6f92ed8fSSimon Glass * out %al,(%dx) 30*6f92ed8fSSimon Glass */ 31*6f92ed8fSSimon Glass 32*6f92ed8fSSimon Glass pushf 33*6f92ed8fSSimon Glass push %rdi /* 32-bit code segment */ 34*6f92ed8fSSimon Glass lea compat(%rip), %rax 35*6f92ed8fSSimon Glass push %rax 36*6f92ed8fSSimon Glass .byte 0x48 /* REX prefix to force 64-bit far return */ 37*6f92ed8fSSimon Glass retf 38*6f92ed8fSSimon Glass.code32 39*6f92ed8fSSimon Glasscompat: 40*6f92ed8fSSimon Glass /* 41*6f92ed8fSSimon Glass * We are now in compatibility mode with a default operand size of 42*6f92ed8fSSimon Glass * 32 bits. First disable paging. 43*6f92ed8fSSimon Glass */ 44*6f92ed8fSSimon Glass movl %cr0, %eax 45*6f92ed8fSSimon Glass andl $~X86_CR0_PG, %eax 46*6f92ed8fSSimon Glass movl %eax, %cr0 47*6f92ed8fSSimon Glass 48*6f92ed8fSSimon Glass /* Invalidate TLB */ 49*6f92ed8fSSimon Glass xorl %eax, %eax 50*6f92ed8fSSimon Glass movl %eax, %cr3 51*6f92ed8fSSimon Glass 52*6f92ed8fSSimon Glass /* Disable Long mode in EFER (Extended Feature Enable Register) */ 53*6f92ed8fSSimon Glass movl $MSR_EFER, %ecx 54*6f92ed8fSSimon Glass rdmsr 55*6f92ed8fSSimon Glass btr $_EFER_LME, %eax 56*6f92ed8fSSimon Glass wrmsr 57*6f92ed8fSSimon Glass 58*6f92ed8fSSimon Glass /* Set up table pointer for _x86boot_start */ 59*6f92ed8fSSimon Glass mov %ebx, %ecx 60*6f92ed8fSSimon Glass 61*6f92ed8fSSimon Glass /* Jump to the required target */ 62*6f92ed8fSSimon Glass pushl %edi /* 32-bit code segment */ 63*6f92ed8fSSimon Glass pushl %esi /* 32-bit target address */ 64*6f92ed8fSSimon Glass retf 65