diff options
Diffstat (limited to 'src/arch/x86_64/boot/boot.S')
| -rw-r--r-- | src/arch/x86_64/boot/boot.S | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/src/arch/x86_64/boot/boot.S b/src/arch/x86_64/boot/boot.S new file mode 100644 index 0000000..1dc2320 --- /dev/null +++ b/src/arch/x86_64/boot/boot.S @@ -0,0 +1,128 @@ +.code32 +.extern begin_long_mode + +.section .boot32.text, "a" + +.set STACK_TOP, 0x03008000 + +.global _start +_start: + cli + mov $STACK_TOP, %esp + pushl $0 + pushl %eax + pushl $0 + pushl %ebx + + call setup_page_tables + call enable_paging + + lgdt gdtp + ljmp $0x08, $begin_long_mode + +setup_page_tables: +/* first 2mb */ + mov $pt_lvl3, %eax + or $0x3, %eax + mov %eax, pt_lvl4 + + mov $pt_lvl2, %eax + or $0x3, %eax + mov %eax, pt_lvl3 + + xor %ecx, %ecx +1: + movl $0x00200000, %eax + mul %ecx + or $0b10000011, %eax + movl $pt_lvl2, %edx + leal (%edx, %ecx, 8), %edx + movl %eax, (%edx) + inc %ecx + cmp $25, %ecx + jne 1b + +/* first 2mb in hh */ + mov $pt_lvl3_hh, %eax + or $0x3, %eax + mov %eax, pt_lvl4 + 4096 - 8 + + mov $pt_lvl2_hh, %eax + or $0x3, %eax + mov %eax, pt_lvl3_hh + 4096 - 16 + + xor %ecx, %ecx +2: + movl $0x00200000, %eax + mul %ecx + or $0b10000011, %eax + movl $pt_lvl2_hh, %edx + leal (%edx, %ecx, 8), %edx + movl %eax, (%edx) + inc %ecx + cmp $25, %ecx + jne 2b + + ret + +.global enable_paging +enable_paging: + /* enable PAE */ + mov %cr4, %edx + or $1<<5 ,%edx + mov %edx, %cr4 + + /* set LME (long mode enable) */ + mov $0xC0000080, %ecx + rdmsr + or $1<<8, %eax + wrmsr + + /* pt_lvl4 */ + mov $pt_lvl4, %eax + mov %eax, %cr3 + + /* enable paging (+ protected mode if not already enabled) */ + mov %cr0, %eax + or $1<<31 + 1<<0, %eax + mov %eax, %cr0 + + ret + + +.section .boot32.rodata + +gdt: +gdt_null = . - gdt + .quad 0 +gdt_code = . - gdt + .long 0xFFFF + .byte 0 + .byte 0x9A + .byte 0xAF + .byte 0 +gdt_data = . - gdt + .long 0xFFFF + .byte 0 + .byte 0x92 + .byte 0xAF + .byte 0 +.global gdtp +gdtp: + .word . - gdt - 1 + .quad gdt + + +.section .boot32.bss +.align 4096 + +pt_lvl4: + .skip 4096 +pt_lvl3: + .skip 4096 +pt_lvl3_hh: + .skip 4096 +pt_lvl2: + .skip 4096 +pt_lvl2_hh: + .skip 4096 |