/*
* Copyright 2012, Alex Smith, alex@alex-smith.me.uk.
* Distributed under the terms of the MIT License.
*/
#include <asm_defs.h>
#define __x86_64__
#include <arch/x86/descriptors.h>
#include "mmu.h"
#undef __x86_64__
#define GDT_LIMIT 0x800
.code32
/*! void long_enter_kernel(int currentCPU, uint64 stackTop)
FUNCTION(long_enter_kernel):
// Preserve the arguments. We may no longer be able to use the stack once
// paging is disabled.
movl 4(%esp), %ebx
movl 8(%esp), %edi
movl 12(%esp), %esi
movl gLongLA57, %ecx
shl $12, %ecx
// Currently running with 32-bit paging tables at an identity mapped
// address. To switch to 64-bit paging we must first disable 32-bit paging,
// otherwise loading the new CR3 will fault.
movl %cr0, %eax
andl $~(1 << 31), %eax
movl %eax, %cr0
// Enable PAE and PGE, and optionally LA57
movl %cr4, %eax
orl $(1 << 5) | (1 << 7), %eax
orl %ecx, %eax
movl %eax, %cr4
// Point CR3 to the kernel's PMLTop.
movl gLongPhysicalPMLTop, %eax
movl %eax, %cr3
// Enable long mode by setting EFER.LME.
movl $0xc0000080, %ecx
rdmsr
orl $(1 << 8), %eax
wrmsr
// Re-enable paging, which will put us in compatibility mode as we are
// currently in a 32-bit code segment.
movl %cr0, %ecx
orl $(1 << 31), %ecx
movl %ecx, %cr0
// Load 64-bit enabled GDT
lgdtl long_gdtr
// Jump into the 64-bit code segment.
ljmp $KERNEL_CODE_SELECTOR, $.Llmode
.align 8
.code64
.Llmode:
// Set data segments.
mov $KERNEL_DATA_SELECTOR, %ax
mov %ax, %ss
xor %ax, %ax
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
// Set the stack pointer.
movl %edi, %esp
shl $32, %rsi
orq %rsi, %rsp
// Clear the stack frame/RFLAGS.
xorq %rbp, %rbp
push $0
popf
// Get arguments and call the kernel entry point.
leaq gKernelArgs(%rip), %rdi
movl %ebx, %esi
movq gLongKernelEntry(%rip), %rax
call *%rax
.data
long_gdtr:
.word BOOT_GDT_SEGMENT_COUNT * 8 - 1
SYMBOL(gLongGDT):
.long 0
SYMBOL(gLongPhysicalPMLTop):
.long 0
SYMBOL(gLongLA57):
.long 0
SYMBOL(gLongKernelEntry):
.quad 0
