forked from Bananymous/banan-os
204 lines
3.6 KiB
ArmAsm
204 lines
3.6 KiB
ArmAsm
# Declare constants for the multiboot header
|
|
.set ALIGN, 1<<0 # align loaded modules on page boundaries
|
|
.set MEMINFO, 1<<1 # provide memory map
|
|
.set VIDEOINFO, 1<<2 # provide video info
|
|
.set MB_FLAGS, ALIGN | MEMINFO | VIDEOINFO # this is the Multiboot 'flag' field
|
|
.set MB_MAGIC, 0x1BADB002 # 'magic number' lets bootloader find the header
|
|
.set MB_CHECKSUM, -(MB_MAGIC + MB_FLAGS) #checksum of above, to prove we are multiboot
|
|
|
|
.set PG_PRESENT, 1<<0
|
|
.set PG_READ_WRITE, 1<<1
|
|
.set PG_PAGE_SIZE, 1<<7
|
|
|
|
.code32
|
|
|
|
# Multiboot header
|
|
.section .multiboot, "aw"
|
|
.align 4
|
|
.long MB_MAGIC
|
|
.long MB_FLAGS
|
|
.long MB_CHECKSUM
|
|
.skip 20
|
|
|
|
.long 0
|
|
.long 800
|
|
.long 600
|
|
.long 32
|
|
|
|
.section .bss, "aw", @nobits
|
|
# Create stack
|
|
.global g_boot_stack_bottom
|
|
g_boot_stack_bottom:
|
|
.skip 16384
|
|
.global g_boot_stack_top
|
|
g_boot_stack_top:
|
|
|
|
.global g_kernel_cmdline
|
|
g_kernel_cmdline:
|
|
.skip 4096
|
|
|
|
# Reserve memory for paging structures,
|
|
# we will identity map first 4 MiB
|
|
|
|
# 0 MiB -> 1 MiB: bootloader stuff
|
|
# 1 MiB -> : kernel
|
|
.align 4096
|
|
boot_pml4:
|
|
.skip 512 * 8
|
|
boot_pdpt1:
|
|
.skip 512 * 8
|
|
boot_pd1:
|
|
.skip 512 * 8
|
|
|
|
.global g_multiboot_info
|
|
g_multiboot_info:
|
|
.skip 8
|
|
.global g_multiboot_magic
|
|
g_multiboot_magic:
|
|
.skip 8
|
|
|
|
.section .text
|
|
|
|
boot_gdt:
|
|
.quad 0x0000000000000000 # null descriptor
|
|
.quad 0x00AF9A000000FFFF # kernel code
|
|
.quad 0x00AF92000000FFFF # kernel data
|
|
boot_gdtr:
|
|
.short . - boot_gdt - 1
|
|
.quad boot_gdt
|
|
|
|
has_cpuid:
|
|
pushfl
|
|
pushfl
|
|
xorl $0x00200000, (%esp)
|
|
popfl
|
|
pushfl
|
|
popl %eax
|
|
xorl (%esp), %eax
|
|
popfl
|
|
testl $0x00200000, %eax
|
|
ret
|
|
|
|
is_64_bit:
|
|
movl $0x80000000, %eax
|
|
cpuid
|
|
cmpl $0x80000001, %eax
|
|
jl .no_extension
|
|
movl $0x80000001, %eax
|
|
cpuid
|
|
testl $(1 << 29), %edx
|
|
ret
|
|
.no_extension:
|
|
cmpl %eax, %eax
|
|
ret
|
|
|
|
check_requirements:
|
|
call has_cpuid
|
|
jz .exit
|
|
call is_64_bit
|
|
jz .exit
|
|
ret
|
|
.exit:
|
|
jmp system_halt
|
|
|
|
copy_kernel_commandline:
|
|
pushl %esi
|
|
pushl %edi
|
|
movl g_multiboot_info, %esi
|
|
addl $16, %esi
|
|
movl (%esi), %esi
|
|
movl $1024, %ecx
|
|
movl $g_kernel_cmdline, %edi
|
|
rep movsl
|
|
popl %edi
|
|
popl %esi
|
|
ret
|
|
|
|
enable_sse:
|
|
movl %cr0, %eax
|
|
andw $0xFFFB, %ax
|
|
orw $0x0002, %ax
|
|
movl %eax, %cr0
|
|
movl %cr4, %eax
|
|
orw $0x0600, %ax
|
|
movl %eax, %cr4
|
|
ret
|
|
|
|
initialize_paging:
|
|
# identity map first 6 MiB
|
|
movl $(0x00000000 + PG_PAGE_SIZE + PG_READ_WRITE + PG_PRESENT), boot_pd1 + 0
|
|
movl $(0x00200000 + PG_PAGE_SIZE + PG_READ_WRITE + PG_PRESENT), boot_pd1 + 8
|
|
movl $(0x00400000 + PG_PAGE_SIZE + PG_READ_WRITE + PG_PRESENT), boot_pd1 + 16
|
|
|
|
# set pdpte1 and pml4e1
|
|
movl $(boot_pd1 + PG_READ_WRITE + PG_PRESENT), boot_pdpt1
|
|
movl $(boot_pdpt1 + PG_READ_WRITE + PG_PRESENT), boot_pml4
|
|
|
|
# enable PAE
|
|
movl %cr4, %ecx
|
|
orl $0x20, %ecx
|
|
movl %ecx, %cr4
|
|
|
|
# set long mode enable bit
|
|
movl $0x100, %eax
|
|
movl $0x000, %edx
|
|
movl $0xC0000080, %ecx
|
|
wrmsr
|
|
|
|
# set address of paging structures
|
|
movl $boot_pml4, %ecx
|
|
movl %ecx, %cr3
|
|
|
|
# enable paging
|
|
movl %cr0, %ecx
|
|
orl $0x80000000, %ecx
|
|
movl %ecx, %cr0
|
|
|
|
ret
|
|
|
|
.global _start
|
|
.type _start, @function
|
|
_start:
|
|
# Initialize stack and multiboot info
|
|
movl $g_boot_stack_top, %esp
|
|
movl %eax, g_multiboot_magic
|
|
movl %ebx, g_multiboot_info
|
|
|
|
call copy_kernel_commandline
|
|
call check_requirements
|
|
call enable_sse
|
|
|
|
call initialize_paging
|
|
|
|
# flush gdt and jump to 64 bit
|
|
lgdt boot_gdtr
|
|
ljmpl $0x08, $long_mode
|
|
|
|
.code64
|
|
long_mode:
|
|
movw $0x10, %ax
|
|
movw %ax, %ss
|
|
|
|
# clear segment registers (unused in x86_64?)
|
|
movw $0x00, %ax
|
|
movw %ax, %ds
|
|
movw %ax, %es
|
|
movw %ax, %fs
|
|
movw %ax, %gs
|
|
|
|
# call global constuctors
|
|
call _init
|
|
|
|
# call to the kernel itself (clear ebp for stacktrace)
|
|
xorq %rbp, %rbp
|
|
call kernel_main
|
|
|
|
# call global destructors
|
|
call _fini
|
|
|
|
system_halt:
|
|
xchgw %bx, %bx
|
|
cli
|
|
1: hlt
|
|
jmp 1b
|