limine/common/protos/limine_32.asm_x86

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bits 32
section .text
global limine_spinup_32
limine_spinup_32:
; Enable EFER.NXE
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cmp dword [esp+32], 0 ; nx_available
je .no_nx
mov ecx, 0xc0000080
rdmsr
bts eax, 11
wrmsr
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.no_nx:
; Enable CR4.LA57
cmp dword [esp+4], 0 ; level5pg
je .no_la57
mov eax, cr4
bts eax, 12
mov cr4, eax
.no_la57:
; Enable CR0.WP
mov eax, cr0
bts eax, 16
mov cr0, eax
cld
mov eax, [esp+8] ; pagemap_top_lv
mov cr3, eax
; Enable CR4.PAE
mov eax, cr4
bts eax, 5
mov cr4, eax
; Enable EFER.LME
mov ecx, 0xc0000080
rdmsr
bts eax, 8
wrmsr
; Enable CR0.PG
mov eax, cr0
bts eax, 31
mov cr0, eax
; Go 64
push 0x28
call .p1
.p1:
add dword [esp], .mode64 - .p1
retfd
bits 64
.mode64:
mov eax, 0x30
mov ds, eax
mov es, eax
mov fs, eax
mov gs, eax
mov ss, eax
; Load 64-bit GDT
mov eax, [rsp+28] ; local_gdt
lgdt [rax]
; Push fake return address
mov rsi, [rsp+20] ; stack
sub rsi, 8
mov qword [rsi], 0
; Prepare iretq frame
mov rax, qword [rsp+12] ; entry_point
push 0x30
push rsi
pushfq
push 0x28
push rax
; Zero out all GPRs
xor eax, eax
xor ebx, ebx
xor ecx, ecx
xor edx, edx
xor esi, esi
xor edi, edi
xor ebp, ebp
xor r8d, r8d
xor r9d, r9d
xor r10d, r10d
xor r11d, r11d
xor r12d, r12d
xor r13d, r13d
xor r14d, r14d
xor r15d, r15d
iretq