diff options
| author | Aleksa Vuckovic <aleksav013@gmail.com> | 2022-08-08 19:50:11 +0200 |
|---|---|---|
| committer | Aleksa Vuckovic <aleksav013@gmail.com> | 2022-08-08 19:50:11 +0200 |
| commit | 0162997df4ae7769bd4fc055b2c03b473846d1f5 (patch) | |
| tree | f6c40a64cbb15cf3fd102e5e8f15b48030e96f4e /kernel/src/boot/boot.S | |
| parent | 71396c5cd460890c52e348687e6e7c864e2dfeed (diff) | |
higher half
Diffstat (limited to 'kernel/src/boot/boot.S')
| -rw-r--r-- | kernel/src/boot/boot.S | 58 |
1 files changed, 43 insertions, 15 deletions
diff --git a/kernel/src/boot/boot.S b/kernel/src/boot/boot.S index bf5251b..81584ce 100644 --- a/kernel/src/boot/boot.S +++ b/kernel/src/boot/boot.S @@ -1,12 +1,13 @@ +.code32 .global _start .extern begin_long_mode -.section .text -.code32 +.set KERNEL_VMA, 0xc0000000 +.section .boot.text, "a" _start: cli - mov $stack_top, %esp + mov $stack_top - KERNEL_VMA, %esp pushl $0 pushl %eax pushl $0 @@ -19,9 +20,9 @@ _start: call setup_page_tables call enable_paging - lgdt gdt_pointer - ljmp $0x08, $begin_long_mode - + addl $KERNEL_VMA, %esp + mov $4f, %ecx + jmp *%ecx check_multiboot: cmp $0x36d76289, %eax @@ -59,27 +60,46 @@ check_long_mode: ret setup_page_tables: - mov $pt_lvl3, %eax + mov $pt_lvl3 - KERNEL_VMA, %eax or $0x3, %eax - mov %eax, pt_lvl4 + mov %eax, pt_lvl4 - KERNEL_VMA - // 0x00000000 - 0x00200000 : 0x00000000 - mov $pt_lvl2, %eax + // 0x00000000 - 0x00200000 : 0x00000000 - 0x00200000 + mov $pt_lvl2 - KERNEL_VMA, %eax or $0x3, %eax - mov %eax, pt_lvl3 + mov %eax, pt_lvl3 - KERNEL_VMA - movl $0, %ecx + // 0xc0000000 - 0xc0200000 : 0xc0000000 - 0xc0200000 + mov $pt_lvl2_hh - KERNEL_VMA, %eax + or $0x3, %eax + mov %eax, pt_lvl3 + 24 - KERNEL_VMA + +// first 2mb + xor %ecx, %ecx 1: movl $0x00200000, %eax mul %ecx or $0b10000011, %eax - movl $pt_lvl2, %edx + movl $pt_lvl2 - KERNEL_VMA, %edx leal (%edx, %ecx, 8), %edx movl %eax, (%edx) inc %ecx cmp $1, %ecx jne 1b +// first 2mb in higher_half + xor %ecx, %ecx +2: + movl $0x00200000, %eax + mul %ecx + or $0b10000011, %eax + movl $pt_lvl2_hh - KERNEL_VMA, %edx + leal (%edx, %ecx, 8), %edx + movl %eax, (%edx) + inc %ecx + cmp $1, %ecx + jne 2b + ret enable_paging: @@ -95,7 +115,7 @@ enable_paging: wrmsr // pt_lvl4 - mov $pt_lvl4, %eax + mov $pt_lvl4 - KERNEL_VMA, %eax mov %eax, %cr3 // enable paging (+ protected mode if not already enabled) @@ -114,6 +134,11 @@ no_cpuid: no_long_mode: hlt +.section .text +4: + lgdt gdt_pointer + ljmp $0x08, $begin_long_mode + .section .bss .align 4096 @@ -123,14 +148,17 @@ stack_bottom: .skip 4096*4 stack_top: + // page tables pt_lvl4: .skip 4096 pt_lvl3: .skip 4096 -// map first 4GB pt_lvl2: .skip 4096 +pt_lvl2_hh: + .skip 4096 + // Access bits .section .rodata |