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Enable SSE support

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The go compiler uses SSE instructions to optimize some of the generated code. We need to explicitly enable SSE support by manipulating the appropriate CR flags; otherwise the kernel will triple-fault
This commit is contained in:
Achilleas Anagnostopoulos 2017-04-24 08:42:15 +01:00 committed by GitHub
parent 5db83cd3c6
commit 2b77a9270f
1 changed files with 35 additions and 0 deletions
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35
arch/x86/asm/rt0.s
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@ -27,6 +27,7 @@ align 4
MULTIBOOT_MAGIC equ 0x36d76289 MULTIBOOT_MAGIC equ 0x36d76289
err_unsupported_bootloader db '[rt0] kernel not loaded by multiboot-compliant bootloader', 0 err_unsupported_bootloader db '[rt0] kernel not loaded by multiboot-compliant bootloader', 0
err_sse_not_available db '[rt0] kernel requires a CPU with SSE support', 0
err_kmain_returned db '[rt0] kMain returned; halting system', 0 err_kmain_returned db '[rt0] kMain returned; halting system', 0
;------------------------------------------------------------------------------ ;------------------------------------------------------------------------------
@ -51,6 +52,9 @@ _rt0_entry:
; stack grows downwards so we need to point ESP to stack_top ; stack grows downwards so we need to point ESP to stack_top
mov esp, stack_top mov esp, stack_top
; Enable SSE
call _rt0_enable_sse
; Load initial GDT ; Load initial GDT
call _rt0_load_gdt call _rt0_load_gdt
@ -162,3 +166,34 @@ NULL_SEG equ gdt0_nil_seg - gdt0
CS_SEG equ gdt0_cs_seg - gdt0 CS_SEG equ gdt0_cs_seg - gdt0
DS_SEG equ gdt0_ds_seg - gdt0 DS_SEG equ gdt0_ds_seg - gdt0
GS_SEG equ gdt0_gs_seg - gdt0 GS_SEG equ gdt0_gs_seg - gdt0
;------------------------------------------------------------------------------
; Enable SSE support. Code taken from:
; http://wiki.osdev.org/SSE#Checking_for_SSE
;------------------------------------------------------------------------------
_rt0_enable_sse:
pushad
; check for SSE
mov eax, 0x1
cpuid
test edx, 1<<25
jz .no_sse
; enable SSE
mov eax, cr0
and ax, 0xFFFB ; clear coprocessor emulation CR0.EM
or ax, 0x2 ; set coprocessor monitoring CR0.MP
mov cr0, eax
mov eax, cr4
or ax, 3 << 9 ; set CR4.OSFXSR and CR4.OSXMMEXCPT at the same time
mov cr4, eax
popad
ret
.no_sse:
mov edi, err_sse_not_available
call write_string
cli
hlt