179 lines
4.2 KiB
ArmAsm
179 lines
4.2 KiB
ArmAsm
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2014, 2015.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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x64/boot.S
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Bootstraps the kernel and passes over control from the boot-loader to the
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kernel main function. It also jumps into long mode!
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*******************************************************************************/
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.section .text
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.text 0x100000
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# Multiboot header.
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.align 4
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.long 0x1BADB002 # Magic.
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.long 0x00000003 # Flags.
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.long -(0x1BADB002 + 0x00000003) # Checksum
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.global _start
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.global __start
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.type _start, @function
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.type __start, @function
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.code32
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_start:
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__start:
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# Initialize the stack pointer. The magic value is from kernel.cpp.
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movl $(stack + 65536), %esp # 64 KiB, see kernel.cpp (See below also)
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# Finish installing the kernel stack into the Task Switch Segment.
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movl %esp, tss + 4
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movl $0, tss + 8
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# Finish installing the Task Switch Segment into the Global Descriptor Table.
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movl $tss, %ecx
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movw %cx, gdt + 0x28 + 2
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shrl $16, %ecx
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movb %cl, gdt + 0x28 + 4
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shrl $8, %ecx
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movb %cl, gdt + 0x28 + 7
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movl $0, gdt + 0x28 + 8
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# We got our multiboot information in various registers.
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pushl $0
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pushl %eax # Multiboot magic value.
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pushl $0
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pushl %ebx # Multiboot information structure pointer.
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# Clear the first $0xE000 bytes following 0x21000.
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movl $0x21000, %edi
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movl %edi, %cr3
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xorl %eax, %eax
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movl $0xE000, %ecx
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rep stosl
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movl %cr3, %edi
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# Set the initial page tables.
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# Note that we OR with 0x7 here to allow user-space access, except in the
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# first 2 MiB. We also do this with 0x200 to allow forking the page.
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# Page-Map Level 4
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movl $0x22207, (%edi)
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addl $0x1000, %edi
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# Page-Directory Pointer Table
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movl $0x23207, (%edi)
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addl $0x1000, %edi
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# Page-Directory (no user-space access here)
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movl $0x24003, (%edi) # (First 2 MiB)
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movl $0x25003, 8(%edi) # (Second 2 MiB)
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addl $0x1000, %edi
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# Page-Table
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# Memory map the first 4 MiB.
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movl $0x3, %ebx
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movl $1024, %ecx
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1:
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movl %ebx, (%edi)
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addl $0x1000, %ebx
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addl $8, %edi
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loop 1b
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# Enable PAE.
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movl %cr4, %eax
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orl $0x20, %eax
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movl %eax, %cr4
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# Enable long mode.
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movl $0xC0000080, %ecx
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rdmsr
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orl $0x100, %eax
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wrmsr
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# Enable paging and enter long mode (still 32-bit)
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movl %cr0, %eax
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orl $0x80000000, %eax
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movl %eax, %cr0
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# Load the Global Descriptor Table pointer register.
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subl $6, %esp
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movw gdt_size_minus_one, %cx
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movw %cx, 0(%esp)
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movl $gdt, %ecx
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movl %ecx, 2(%esp)
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lgdt 0(%esp)
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addl $6, %esp
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# Now use the 64-bit code segment, and we are in full 64-bit mode.
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ljmp $0x08, $2f
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.code64
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2:
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# Switch ds, es, fs, gs, ss to the kernel data segment (0x10).
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movw $0x10, %cx
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movw %cx, %ds
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movw %cx, %es
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movw %cx, %ss
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# Switch the task switch segment register to the task switch segment (0x28).
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movw $(0x28 /* TSS */ | 0x3 /* RPL */), %cx
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ltr %cx
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# Switch to the thread local fs and gs segments.
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movw $(0x20 /* DS */ | 0x3 /* RPL */), %cx
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movw %cx, %fs
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movw %cx, %gs
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# Enable the floating point unit.
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mov %cr0, %rax
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and $0xFFFD, %ax
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or $0x10, %ax
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mov %rax, %cr0
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fninit
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# Enable Streaming SIMD Extensions.
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mov %cr0, %rax
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and $0xFFFB, %ax
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or $0x2, %ax
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mov %rax, %cr0
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mov %cr4, %rax
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or $0x600, %rax
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mov %rax, %cr4
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# Store a copy of the initialial floating point registers.
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fxsave fpu_initialized_regs
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# Enter the high-level kernel proper.
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pop %rsi # Multiboot information structure pointer.
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pop %rdi # Multiboot magic value.
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call KernelInit
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jmp HaltKernel
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.size _start, . - _start
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.size __start, . - __start
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.global HaltKernel
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.type HaltKernel, @function
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HaltKernel:
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cli
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hlt
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jmp HaltKernel
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.size HaltKernel, . - HaltKernel
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