move old kernel code (for now) into kernel/old, trying to get long mode

1 files changed, 158 insertions, 0 deletions

diff --git a/kernel/entry.S b/kernel/entry.S
new file mode 100644
index 0000000..5d763ed
--- /dev/null
+++ b/kernel/entry.S
@@ -0,0 +1,158 @@
+	.globl _start
+	.globl kernel_pml4
+	.globl kernel_pdpt_0
+	.globl kernel_pd_0
+	.globl kernel_pt_0
+	.globl paging_pt
+	.globl bootstrap_pt
+	.extern main
+	.extern GDT
+
+	.section .bss
+
+	# kernel page tables
+	.align 4096
+kernel_pml4:            # reserve memory for initial 512 pml4 entires
+	.skip 4096
+kernel_pdpt_0:          # reserve memory for initial 512 pdpt entires
+	.skip 4096
+kernel_pd_0:            # reserve memory for initial 512 pd entries
+	.skip 4096
+kernel_pt_0:            # reserve memory for initial 512 pt entries
+	.skip 4096
+paging_pt:              # reserve pages for pager mappings
+	.skip 4096
+bootstrap_pt:           # reserve pages to bootstrap pager
+	.skip 4096
+
+	# kernel stack
+	.align 16
+kern_stack_start:
+	.skip 8192
+kern_stack_end:
+
+	.section .rodata
+	.align 16
+
+	# access bits
+	.set PRESENT,   1 << 7
+	.set NOT_SYS,   1 << 4
+	.set EXEC,      1 << 3
+	.set DC,        1 << 2
+	.set RW,        1 << 1
+	.set ACCESSED,  1 << 0
+
+	# flag bits
+	.set GRAN_4K,   1 << 7
+	.set SZ_32,     1 << 6
+	.set LONG_MODE, 1 << 5
+
+	# kernel gdt (long mode)
+GDT:
+	GDT.Null:
+		.quad 0
+
+	GDT.Code:
+		.byte 0
+		.byte PRESENT | NOT_SYS | EXEC | RW
+		.byte GRAN_4K | LONG_MODE | 0xF
+		.byte 0
+
+	GDT.Data:
+		.long 0xFFFF
+		.byte 0
+		.byte PRESENT | NOT_SYS | RW
+		.byte GRAN_4K | SZ_32 | 0xF
+		.byte 0
+
+	GDT.TSS:
+		.long 0x00000068
+		.long 0x00CF8900
+
+	GDT.Pointer:
+		.short . - GDT - 1
+		.quad GDT - .
+
+	.section .text
+	.code32
+
+_start:
+    # enable interrupts
+	cli
+
+    # setup stack
+	movl	$kern_stack_end, %esp
+	movl	$kern_stack_end, %ebp
+
+	# save multiboot (if using multiboot)
+	pushl	$0
+	push 	%ebx
+	pushl	$0
+	push 	%eax
+
+	# zero out kernel page table
+	movl	$0x1000, %edi    # kernel is loaded at 0x1000
+	movl	%edi, %cr3
+	xorl	%eax, %eax
+	movl	$4096, %ecx      # zero 4096 pages
+	rep		stosl
+	movl	%cr3, %edi
+
+	# identity map kernel
+	movl	$kernel_pdpt_0 + 3, (%edi)      # Set the uint32_t at the desination index to 0x2003.
+	movl	$kernel_pdpt_0, %edi            # Add 0x1000 to the desination index.
+	movl	$kernel_pd_0 + 3, (%edi)        # Set the uint32_t at the desination index to 0x3003.
+	movl	$kernel_pd_0, %edi              # Add 0x1000 to the desination index.
+	movl	$kernel_pt_0 + 3, (%edi)        # Set the uint32_t at the desination index to 0x4003.
+	movl	$kernel_pt_0, %edi              # Add 0x1000 to the desination index.
+
+	movl	$0x00000003, %ebx       # Entry value to set
+	movl	$512, %ecx              # Loop count
+
+set_entry:
+	# set entires in mapping
+	movl	%ebx, (%edi)            # Set the uint32_t at the desination index to the B-register
+	addl	$0x1000, %ebx           # Add 0x1000 to the B-register
+	addl	$8, %edi                # Add eight to the desination index
+	loop	set_entry
+
+	# enable page address extension
+	movl	%cr4, %eax
+	orl		$(1 << 5), %eax
+	movl	%eax, %cr4
+
+	# enable long mode
+	movl	$0xC0000080, %eax
+	rdmsr
+	orl		$(1 << 8), %eax
+	wrmsr
+
+	# enable paging
+	movl	%cr0, %eax
+	orl		$(1 << 31), %eax
+	movl	%eax, %cr0
+
+	# load gdt
+	lgdt	GDT.Pointer
+	ljmp	$16, $code64
+
+	.code64
+code64:
+
+	movw	$16, %dx        # set segment registers
+	movw	%dx, %ds
+	movw	%dx, %ss
+
+	xorq	%rbp, %rbp      # set ebp to 0 so we know where to end stack traces
+
+	pop		%rdi            # pop possible multiboot header
+	pop		%rsi
+
+	sti
+	call	main
+	cli
+
+ halt:
+	hlt
+	jmp		halt
+