diff --git a/bootloader/arch/x86_64/boot.S b/bootloader/arch/x86_64/boot.S index 86763eb23f..689a909fcf 100644 --- a/bootloader/arch/x86_64/boot.S +++ b/bootloader/arch/x86_64/boot.S @@ -41,7 +41,7 @@ puts: movb $0x0E, %ah movb $0x00, %bh -.puts_loop: + .puts_loop: lodsb test %al, %al @@ -50,7 +50,7 @@ puts: int $0x10 jmp .puts_loop -.puts_done: + .puts_done: popw %ax popw %bx popw %si @@ -155,7 +155,7 @@ find_gpt_partition_entry: # although read will fail with more than 0x80 movw (gpt_header + 80), %cx -.loop_gpt_entries: + .loop_gpt_entries: pushw %cx movw $16, %cx call memcmp @@ -169,11 +169,11 @@ find_gpt_partition_entry: loop .loop_gpt_entries -.no_gpt_partition_found: + .no_gpt_partition_found: movb $0, %al ret -.gpt_partition_found: + .gpt_partition_found: movb $1, %al ret @@ -186,11 +186,13 @@ stage1_main: # setup stack movw %ax, %ss - movw $0x7C00, %sp + movl $0x7C00, %esp # save boot disk number movb %dl, (boot_disk_number) + # FIXME: validate boot disk (needs size optizations) + # confirm that int 13h extensions are available clc movb $0x41, %ah @@ -241,23 +243,23 @@ halt: hlt jmp halt -.no_int13h_ext: + .no_int13h_ext: mov $no_int13_ext_msg, %si jmp print_and_halt -.read_failed: + .read_failed: mov $read_failed_msg, %si jmp print_and_halt -.not_gpt_partition: + .not_gpt_partition: mov $not_gpt_partition_msg, %si jmp print_and_halt -.no_bios_boot_partition: + .no_bios_boot_partition: mov $no_bios_boot_partition_msg, %si jmp print_and_halt -.too_gpt_big_entries: + .too_gpt_big_entries: mov $too_gpt_big_entries_msg, %si jmp print_and_halt @@ -341,12 +343,12 @@ print_backspace: decb %dl jmp .print_backspace_do_print -.print_backspace_go_line_up: + .print_backspace_go_line_up: # decrease row and set column to the last one decb %dh movb $(SCREEN_WIDTH - 1), %dl -.print_backspace_do_print: + .print_backspace_do_print: # set cursor position movb $0x02, %ah int $0x10 @@ -359,7 +361,7 @@ print_backspace: movb $0x02, %ah int $0x10 -.print_backspace_done: + .print_backspace_done: popa ret @@ -375,7 +377,7 @@ printnum: movw $printnum_buffer, %si xorw %cx, %cx -.printnum_fill_loop: + .printnum_fill_loop: # fill buffer with all remainders ax % bx xorw %dx, %dx divw %bx @@ -393,21 +395,21 @@ printnum: xchgw %dx, %cx subw %dx, %cx movb $'0', %al -.printnum_pad_zeroes: + .printnum_pad_zeroes: call putc loop .printnum_pad_zeroes movw %dx, %cx -.printnum_print_loop: + .printnum_print_loop: decw %si movb (%si), %al cmpb $10, %al jae 1f addb $'0', %al jmp 2f -1: addb $('a' - 10), %al -2: call putc + 1: addb $('a' - 10), %al + 2: call putc loop .printnum_print_loop popa @@ -423,15 +425,39 @@ isprint: cmpb $0x7E, %al ja .isprint_done cmpb %al, %al -.isprint_done: + .isprint_done: + ret + + +# check if drive exists +# dl: drive number +# return: +# al: 1 if disk is usable, 0 otherwise +drive_exists: + pusha + + movb $0x48, %ah + movw $disk_drive_parameters, %si + movw $0x1A, (disk_drive_parameters) # set buffer size + + clc + int $0x13 + jc .drive_exists_nope + + popa + movb $1, %al + ret + + .drive_exists_nope: + popa + movb $0, %al ret # fills memory map data structure # doesn't return on error +# NO REGISTERS SAVED get_memory_map: - pusha - movl $0, (memory_map_entry_count) movl $0x0000E820, %eax @@ -445,7 +471,7 @@ get_memory_map: # If first call returs with CF set, the call failed jc .get_memory_map_error -.get_memory_map_rest: + .get_memory_map_rest: cmpl $0x534D4150, %eax jne .get_memory_map_error @@ -471,25 +497,23 @@ get_memory_map: # BIOS can indicate end of list by setting CF jnc .get_memory_map_rest -.get_memory_map_done: - popa + .get_memory_map_done: ret -.get_memory_map_error: + .get_memory_map_error: movw $memory_map_error_msg, %si jmp print_and_halt # fills command line buffer +# NO REGISTERS SAVED get_command_line: - pusha - movw $command_line_enter_msg, %si call puts movw $command_line_buffer, %di -.get_command_line_loop: + .get_command_line_loop: call getc cmpb $'\b', %al @@ -513,7 +537,7 @@ get_command_line: jmp .get_command_line_loop -.get_command_line_backspace: + .get_command_line_backspace: # don't do anything if at the beginning cmpw $command_line_buffer, %di je .get_command_line_loop @@ -526,42 +550,18 @@ get_command_line: jmp .get_command_line_loop -.get_command_line_done: + .get_command_line_done: # null terminate command line movb $0, (%di) call print_newline - popa ret -stage2_main: - # clear screen and enter 80x25 text mode - movb $0x03, %al - movb $0x00, %ah - int $0x10 - - # print hello message - movw $hello_msg, %si - call puts - call print_newline - - call get_memory_map - call get_command_line - - call print_newline - - movw $start_kernel_load_msg, %si - call puts - call print_newline - - movw $command_line_msg, %si - call puts - movw $command_line_buffer, %si - call puts - call print_newline - +# print memory map from memory_map_entries +# NO REGISTERS SAVED +print_memory_map: movw $memory_map_msg, %si call puts call print_newline @@ -572,7 +572,7 @@ stage2_main: movw $16, %bx movw $4, %cx -.loop_memory_map: + .loop_memory_map: movb $' ', %al call putc call putc @@ -619,10 +619,212 @@ stage2_main: decl %edx jnz .loop_memory_map + ret + + +# find root disk and populate root_disk_drive_number field +# NO REGISTERS SAVED +find_root_disk: + movb $0x80, %dl + + .find_root_disk_loop: + call drive_exists + testb %al, %al + jz .find_root_disk_not_found + + # read GPT header + xorw %bx, %bx + movl $1, %eax + movw $1, %cx + movw $gpt_header, %di + call read_from_disk + + # confirm header (starts with 'EFI PART') + cmpl $0x20494645, (gpt_header + 0) + jne .find_root_disk_next_disk + cmpl $0x54524150, (gpt_header + 4) + jne .find_root_disk_next_disk + + # compare disk GUID + movw $root_disk_guid, %si + movw $(gpt_header + 56), %di + movw $16, %cx + call memcmp + testb %al, %al + jz .find_root_disk_next_disk + + movb %dl, (root_disk_drive_number) + ret + + .find_root_disk_next_disk: + incb %dl + jmp .find_root_disk_loop + + .find_root_disk_not_found: + movw $no_root_disk_msg, %si + jmp print_and_halt + + +# finds root partition from root disk +# fills root_partition_entry data structure +# NOTE: assumes GPT header is in `gpt_header` +# NO REGISTERS SAVED +find_root_partition: + pushl %ebp + movl %esp, %ebp + subl $16, %esp + + # esp + 0: 8 byte entry array lba + movl (gpt_header + 72), %eax + movl %eax, 0(%esp) + movl (gpt_header + 76), %eax + movl %eax, 4(%esp) + # FIXME: check that bits 48-63 are zero + + # esp + 8: 4 byte entries per sector + xorl %edx, %edx + movl $SECTOR_SIZE, %eax + divl (gpt_header + 84) + movl %eax, 8(%esp) + + # esp + 12: 4 byte entries remaining + movl (gpt_header + 80), %eax + testl %eax, %eax + jz .find_root_partition_not_found + movl %eax, 12(%esp) + + .find_root_partition_read_entry_section: + movl 0(%esp), %eax + movl 4(%esp), %ebx + movw $1, %cx + movb (root_disk_drive_number), %dl + movw $sector_buffer, %di + call read_from_disk + + # ecx: min(entries per section, entries remaining) + movl 8(%esp), %ecx + cmpl 12(%esp), %ecx + jae .find_root_partition_got_entry_count + movl 12(%esp), %ecx + + .find_root_partition_got_entry_count: + # update entries remaining + subl %ecx, 12(%esp) + + # si: entry pointer + movw $sector_buffer, %si + + .find_root_partition_loop_entries: + # temporarily save cx in dx + movw %cx, %dx + + # check that entry is used + movw $16, %cx + movw $zero_guid, %di + call memcmp + test %al, %al + jnz .find_root_partition_next_entry + + # compare entry guid to root guid + movw $16, %cx + addw $16, %si + movw $root_partition_guid, %di + call memcmp + subw $16, %si + + testb %al, %al + jnz .find_root_partition_found + + .find_root_partition_next_entry: + + # restore cx + movw %dx, %cx + + # entry pointer += entry size + addw (gpt_header + 84), %si + loop .find_root_partition_loop_entries + + # entry not found in this sector + + # increment 8 byte entry array lba + incl 0(%esp) + jno .find_root_partition_no_overflow + incl 4(%esp) + + .find_root_partition_no_overflow: + # loop to read next section if entries remaining + cmpl $0, 12(%esp) + jnz .find_root_partition_read_entry_section + + .find_root_partition_not_found: + movw $no_root_partition_msg, %si + jmp print_and_halt + + .find_root_partition_found: + # copy entry to buffer + movw $root_partition_entry, %di + movw $128, %cx + rep movsb + + leavel + ret + + +stage2_main: + # clear screen and enter 80x25 text mode + movb $0x03, %al + movb $0x00, %ah + int $0x10 + + # print hello message + movw $hello_msg, %si + call puts; call print_newline + + call get_memory_map + call get_command_line + + call print_newline + + movw $start_kernel_load_msg, %si + call puts; call print_newline + + call print_memory_map + + call find_root_disk + movw $root_disk_found_msg, %si + call puts; call print_newline + + call find_root_partition + movw $root_partition_found_msg, %si + call puts; call print_newline + + movw $16, %bx + movw $2, %cx + movw (root_partition_entry + 38), %ax; call printnum + movw (root_partition_entry + 36), %ax; call printnum + movw (root_partition_entry + 34), %ax; call printnum + movw (root_partition_entry + 32), %ax; call printnum + + movb $'-', %al; call putc + movb $'>', %al; call putc + + movw (root_partition_entry + 46), %ax; call printnum + movw (root_partition_entry + 44), %ax; call printnum + movw (root_partition_entry + 42), %ax; call printnum + movw (root_partition_entry + 40), %ax; call printnum jmp halt +# These will be patched during bootloader installation +root_disk_guid: + .ascii "root disk guid " +root_partition_guid: + .ascii "root part guid " +zero_guid: + .quad 0 + .quad 0 + hello_msg: .asciz "This is banan-os bootloader" @@ -639,6 +841,16 @@ memory_map_error_msg: start_kernel_load_msg: .asciz "Starting to load kernel" +root_disk_found_msg: + .asciz "Root disk found!" +no_root_disk_msg: + .asciz "Root disk not found" + +root_partition_found_msg: + .asciz "Root partition found!" +no_root_partition_msg: + .asciz "Root partition not found" + stage2_end: @@ -650,12 +862,24 @@ gpt_header: gpt_entry_data: .skip SECTOR_SIZE +sector_buffer: + .skip SECTOR_SIZE + +disk_drive_parameters: + .skip 0x1A + disk_address_packet: .skip 16 printnum_buffer: .skip 10 +root_disk_drive_number: + .skip 1 + +root_partition_entry: + .skip 128 + memory_map_entry_count: .skip 4 # 100 entries should be enough...