101 lines
2.3 KiB
NASM
101 lines
2.3 KiB
NASM
; TODO move this file to something like "system_check", now that we do ram checks here
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[extern _meminfo_loc]
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detect_arch:
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; todo: figure out how to just handle invalid opcode exceptions, it would be faster and (maybe?) easier
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; todo: digest this part a little better when it's _not_ 1am.
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pushfd ; pushes eflags to stack
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pushfd ; pushes eflags to stack a second time
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xor dword [esp], 0x00200000 ; inverses the ID bit to see if cpuid is a thing
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pop eax ;gets our modified cpuid back
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xor eax, [esp] ; checks with the first time we pushed it; the OG eflag
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popfd ; pops the flags back I guess?
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and eax, 0x00200000 ; checks to see if the bit was inverted
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jz .print_cpuid_error
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;now we detect if we support long slong (aka 64 bit)
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;https://www.amd.com/system/files/TechDocs/25481.pdf page 21
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;So apperently some dumbass engineers thought it would be funny to sell CPUs that have the long mode bit set without it being supported, dispite including it in their own documentation.
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;there's a work around by checking other bits, and it's a low priority TODO. However, I really think us coming accross this will be extremely rare.
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mov eax, 0x80000001
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cpuid ;cpuid returns into edx
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and edx, 0x0020000000 ; the 21st bit is cpuid.
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jz .print_long_error
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mov eax, 0x00000001
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cpuid
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and edx, 0x00000200
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jz .print_apic_error
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mov bx, .no_error
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mov cx, 0
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call bios_print
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;mapping memory
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mov ax, 0
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mov es, ax
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mov ax, _meminfo_loc
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mov di, ax
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mov eax, 0xe820
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mov ebx, 0
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mov ecx, 24
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mov edx, 0x534d4150
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int 0x15
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jc .print_mem_error
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cmp eax, 0x534D4150
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jne .print_mem_error
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.mem_detect_loop:
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add di, 24
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mov [di + 20], dword 1
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mov eax, 0xe820
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mov ecx, 24
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int 0x15
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jc .mem_detected
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cmp ebx, 0
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je .mem_detected
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jmp .mem_detect_loop
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.mem_detected:
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ret
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.print_cpuid_error:
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mov bx, .cpuid_error
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mov cx, 0
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call bios_print
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jmp $
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.print_long_error:
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mov bx, .arch_error ; lets just test for now
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mov cx, 0
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call bios_print
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jmp $
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.print_apic_error:
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mov bx, .apic_error
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mov cx, 0
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call bios_print
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.print_mem_error:
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mov bx, .mem_error
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mov cx, 0
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call bios_print
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.cpuid_error:
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db "No CPUID capabilitity", 0x0
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.arch_error:
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db "This operating system was compiled to run in 64 bit mode!", 0x0
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.apic_error:
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db "No apic support", 0x0
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.mem_error:
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db "Could not get information on memory!", 0x0
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.no_error:
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db "CPU info gathered!", 0x0
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