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| author | Freya Murphy <freya@freyacat.org> | 2025-04-03 14:38:56 -0400 |
|---|---|---|
| committer | Freya Murphy <freya@freyacat.org> | 2025-04-03 14:38:56 -0400 |
| commit | 77d19384200310e883217da6933425ab2c2e22e8 (patch) | |
| tree | 987f7c6501bed9941b6eabc2aa2eab1dd6537115 /kernel/entry.S | |
| parent | move old kernel code (for now) into kernel/old, trying to get long mode (diff) | |
| download | comus-77d19384200310e883217da6933425ab2c2e22e8.tar.gz comus-77d19384200310e883217da6933425ab2c2e22e8.tar.bz2 comus-77d19384200310e883217da6933425ab2c2e22e8.zip | |
working entry for long mode
Diffstat (limited to '')
| -rw-r--r-- | kernel/entry.S | 75 |
1 files changed, 48 insertions, 27 deletions
diff --git a/kernel/entry.S b/kernel/entry.S index 5d763ed..caaa239 100644 --- a/kernel/entry.S +++ b/kernel/entry.S @@ -8,6 +8,22 @@ .extern main .extern GDT + .section .multiboot + .align 8 + + # multiboot header +mb_start: + # magic + .long 0xe85250d6 + .long 0 + .long mb_end - mb_start + .long 0x100000000 - (0xe85250d6 + (mb_end - mb_start)) + # null + .short 0 + .short 0 + .long 8 +mb_end: + .section .bss # kernel page tables @@ -49,29 +65,35 @@ kern_stack_end: # kernel gdt (long mode) GDT: - GDT.Null: - .quad 0 + # Null Segment + .equ GDT.Null, . - GDT + .quad 0 - GDT.Code: - .byte 0 - .byte PRESENT | NOT_SYS | EXEC | RW - .byte GRAN_4K | LONG_MODE | 0xF - .byte 0 + # Code segment + .equ GDT.Code, . - GDT + .long 0xFFFF + .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 + # Data segment + .equ GDT.Data, . - GDT + .long 0xFFFF + .byte 0 + .byte PRESENT | NOT_SYS | RW + .byte GRAN_4K | SZ_32 | 0xF + .byte 0 - GDT.TSS: - .long 0x00000068 - .long 0x00CF8900 + # TSS segment + .equ GDT.TSS, . - GDT + .long 0x00000068 + .long 0x00CF8900 - GDT.Pointer: - .short . - GDT - 1 - .quad GDT - . + # GDT Pointer + .equ GDT.Pointer, . + .word . - GDT - 1 + .quad GDT .section .text .code32 @@ -91,7 +113,7 @@ _start: push %eax # zero out kernel page table - movl $0x1000, %edi # kernel is loaded at 0x1000 + movl $0x1000, %edi # pml4 located at 0x1000 movl %edi, %cr3 xorl %eax, %eax movl $4096, %ecx # zero 4096 pages @@ -106,15 +128,15 @@ _start: 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 + movl $0x03, %ebx # Entry value to set + movl $512, %ecx # Loop count -set_entry: +_start.SetEntry: # 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 + loop _start.SetEntry # enable page address extension movl %cr4, %eax @@ -122,7 +144,7 @@ set_entry: movl %eax, %cr4 # enable long mode - movl $0xC0000080, %eax + movl $0xC0000080, %ecx rdmsr orl $(1 << 8), %eax wrmsr @@ -134,7 +156,7 @@ set_entry: # load gdt lgdt GDT.Pointer - ljmp $16, $code64 + ljmp $GDT.Code, $code64 .code64 code64: @@ -148,7 +170,6 @@ code64: pop %rdi # pop possible multiboot header pop %rsi - sti call main cli |