forked from Bananymous/banan-os
340 lines
5.1 KiB
ArmAsm
340 lines
5.1 KiB
ArmAsm
.set PG_PRESENT, 1<<0
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.set PG_READ_WRITE, 1<<1
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.set PG_PAGE_SIZE, 1<<7
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.set FB_WIDTH, 800
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.set FB_HEIGHT, 600
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.set FB_BPP, 32
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#define KERNEL_OFFSET 0xC0000000
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#define V2P(vaddr) ((vaddr) - KERNEL_OFFSET)
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.code32
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# multiboot2 header
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.section .multiboot, "aw"
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.align 8
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multiboot_start:
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.long 0x1BADB002
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.long (1 << 2) # page align modules
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.long -(0x1BADB002 + (1 << 2))
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.long 0
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.long 0
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.long 0
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.long 0
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.long 0
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.long 0
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.long FB_WIDTH
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.long FB_HEIGHT
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.long FB_BPP
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multiboot_end:
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.align 8
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multiboot2_start:
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.long 0xE85250D6
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.long 0
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.long multiboot2_end - multiboot2_start
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.long -(0xE85250D6 + (multiboot2_end - multiboot2_start))
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# framebuffer tag
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.align 8
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.short 5
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.short 0
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.long 20
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.long FB_WIDTH
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.long FB_HEIGHT
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.long FB_BPP
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# legacy start
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.align 8
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.short 3
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.short 0
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.long 12
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.long V2P(_start)
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# page align modules
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.align 8
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.short 6
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.short 0
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.long 8
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.align 8
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.short 0
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.short 0
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.long 8
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multiboot2_end:
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.section .bananboot, "aw"
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.align 8
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bananboot_start:
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.long 0xBABAB007
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.long -(0xBABAB007 + FB_WIDTH + FB_HEIGHT + FB_BPP)
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.long FB_WIDTH
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.long FB_HEIGHT
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.long FB_BPP
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bananboot_end:
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.section .bss, "aw", @nobits
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.global g_boot_stack_top
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g_boot_stack_bottom:
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.skip 4096 * 4
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g_boot_stack_top:
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.global g_kernel_cmdline
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g_kernel_cmdline:
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.skip 4096
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bootloader_magic:
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.skip 8
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bootloader_info:
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.skip 8
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.section .data
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# Map first GiB to 0x00000000 and 0xC0000000
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.align 32
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boot_pdpt:
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.long V2P(boot_pd) + (PG_PRESENT)
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.long 0
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.quad 0
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.quad 0
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.long V2P(boot_pd) + (PG_PRESENT)
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.long 0
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.align 4096
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boot_pd:
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.set i, 0
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.rept 512
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.long V2P(boot_pts) + i + (PG_READ_WRITE | PG_PRESENT)
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.long 0
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.set i, i + 0x1000
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.endr
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boot_pts:
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.set i, 0
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.rept 512
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.rept 512
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.long i + (PG_READ_WRITE | PG_PRESENT)
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.long 0
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.set i, i + 0x1000
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.endr
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.endr
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boot_gdt:
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.quad 0x0000000000000000 # null descriptor
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.quad 0x00CF9A000000FFFF # kernel code
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.quad 0x00CF92000000FFFF # kernel data
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boot_gdtr:
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.short . - boot_gdt - 1
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.long V2P(boot_gdt)
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.global g_ap_startup_done
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g_ap_startup_done:
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.byte 0
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.global g_ap_running_count
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g_ap_running_count:
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.byte 0
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.global g_ap_stack_loaded
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g_ap_stack_loaded:
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.byte 0
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.section .text
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has_cpuid:
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pushfl
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pushfl
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xorl $0x00200000, (%esp)
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popfl
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pushfl
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popl %eax
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xorl (%esp), %eax
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popfl
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testl $0x00200000, %eax
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ret
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has_pae:
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movl $0, %eax
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cpuid
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testl $(1 << 6), %edx
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ret
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has_sse:
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movl $1, %eax
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cpuid
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testl $(1 << 25), %edx
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ret
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check_requirements:
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call has_cpuid
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jz .exit
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call has_pae
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jz .exit
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call has_sse
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jz .exit
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ret
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.exit:
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jmp system_halt
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enable_sse:
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movl %cr0, %eax
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andw $0xFFFB, %ax
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orw $0x0002, %ax
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movl %eax, %cr0
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movl %cr4, %eax
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orw $0x0600, %ax
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movl %eax, %cr4
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ret
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initialize_paging:
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# enable PAE
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movl %cr4, %ecx
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orl $(1 << 5), %ecx
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movl %ecx, %cr4
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# load page tables
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movl $V2P(boot_pdpt), %ecx
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movl %ecx, %cr3
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# enable paging
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movl %cr0, %ecx
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orl $(1 << 31), %ecx
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movl %ecx, %cr0
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ret
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.global _start
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.type _start, @function
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_start:
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cli; cld
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# save bootloader magic and info
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movl %eax, V2P(bootloader_magic)
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movl %ebx, V2P(bootloader_info)
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# load boot stack
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movl $V2P(g_boot_stack_top), %esp
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# load boot GDT
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lgdt V2P(boot_gdtr)
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ljmpl $0x08, $V2P(gdt_flush)
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gdt_flush:
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# set correct segment registers
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movw $0x10, %ax
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movw %ax, %ds
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movw %ax, %ss
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movw %ax, %es
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# do processor initialization
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call check_requirements
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call enable_sse
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call initialize_paging
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# load higher half stack pointer
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movl $g_boot_stack_top, %esp
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# jump to higher half
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leal higher_half, %ecx
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jmp *%ecx
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higher_half:
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# call global constuctors
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call _init
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movl $g_init_array_start, %ebx
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jmp 2f
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1: call *(%ebx)
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addl $4, %ebx
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2: cmpl $g_init_array_end, %ebx
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jne 1b
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# call to the kernel itself (clear ebp for stacktrace)
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xorl %ebp, %ebp
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subl $8, %esp
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pushl bootloader_info
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pushl bootloader_magic
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call kernel_main
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addl $16, %esp
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# call global destructors
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call _fini
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system_halt:
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xchgw %bx, %bx
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cli
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1: hlt
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jmp 1b
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#define AP_V2P(vaddr) ((vaddr) - ap_trampoline + 0xF000)
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.section .ap_init, "ax"
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.code16
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.global ap_trampoline
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ap_trampoline:
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jmp 1f
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.align 8
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ap_stack_ptr:
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.skip 4
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ap_stack_loaded:
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.skip 1
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1: cli; cld
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ljmpl $0x00, $AP_V2P(ap_cs_clear)
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ap_cs_clear:
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# load ap gdt and enter protected mode
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lgdt AP_V2P(ap_gdtr)
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movl %cr0, %eax
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orb $1, %al
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movl %eax, %cr0
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ljmpl $0x08, $AP_V2P(ap_protected_mode)
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.code32
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ap_protected_mode:
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movw $0x10, %ax
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movw %ax, %ds
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movw %ax, %ss
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movw %ax, %es
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movl AP_V2P(ap_stack_ptr), %esp
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movb $1, AP_V2P(ap_stack_loaded)
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leal V2P(enable_sse), %ecx; call *%ecx
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leal V2P(initialize_paging), %ecx; call *%ecx
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# load boot gdt and enter long mode
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lgdt V2P(boot_gdtr)
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ljmpl $0x08, $AP_V2P(ap_flush_gdt)
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ap_flush_gdt:
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# move stack pointer to higher half
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movl %esp, %esp
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addl $KERNEL_OFFSET, %esp
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# jump to higher half
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leal ap_higher_half, %ecx
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jmp *%ecx
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ap_higher_half:
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# clear rbp for stacktrace
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xorl %ebp, %ebp
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1: pause
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cmpb $0, g_ap_startup_done
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jz 1b
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lock incb g_ap_running_count
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call ap_main
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jmp system_halt
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ap_gdt:
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.quad 0x0000000000000000 # null descriptor
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.quad 0x00CF9A000000FFFF # 32 bit code
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.quad 0x00CF92000000FFFF # 32 bit data
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ap_gdtr:
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.short . - ap_gdt - 1
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.long ap_gdt
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