123 lines
3.5 KiB
NASM
123 lines
3.5 KiB
NASM
;=----------------------------------------------------------------------------=;
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; OS on Kaleid ;
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; ;
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; Desc: System call & userspace related functions ;
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; ;
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; ;
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; Copyright © 2018-2021 The OS/K Team ;
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; ;
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; This file is part of OS/K. ;
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; ;
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; OS/K is free software: you can redistribute it and/or modify ;
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; it under the terms of the GNU General Public License as published by ;
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; the Free Software Foundation, either version 3 of the License, or ;
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; (at your option) any later version. ;
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; ;
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; OS/K is distributed in the hope that it will be useful, ;
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; but WITHOUT ANY WARRANTY; without even the implied warranty of ;
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;
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; GNU General Public License for more details. ;
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; ;
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; You should have received a copy of the GNU General Public License ;
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; along with OS/K. If not, see <https://www.gnu.org/licenses/>. ;
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;=----------------------------------------------------------------------------=;
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[BITS 64]
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%include "kaleid/kernel/ke/cpuf.inc"
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global KeJumpToUserspace
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global KeSyscall
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global syscallPreHandler
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extern _KeSyscallHandler
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;;
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;; System call pre-handler
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;;
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syscallPreHandler:
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push r15
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push r14
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push r13
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push r12
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push r11
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push 0
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push r9
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push r8
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push rbp
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push 0
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push 0
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push 0
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push rcx
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push rbx
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push rax
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mov rax, cr8
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push rax
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mov rax, cr4
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push rax
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mov rax, cr3
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push rax
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mov rax, cr2
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push rax
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mov rax, cr0
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push rax
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mov rcx, 0xC0000080
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rdmsr
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push rax
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; Call the C routine to dispatch interrupts
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cld ; DF must be cleared by the caller
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mov rsi, rsp ; First argument points to the processor state
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mov rbp, 0 ; Terminate stack traces here
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call _KeSyscallHandler
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; pop the control registers
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add rsp, 48
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; pop registers except return value
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pop rbx
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pop rbx ; 2x rbx to discard rax
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pop rcx
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pop rdx
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pop rsi
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pop rdi
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pop rbp
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pop r8
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pop r9
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pop r10
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pop r11
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pop r12
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pop r13
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pop r14
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pop r15
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; pop the error code and interrupt id
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add rsp, 16
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iretq
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;;
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;; To get ring3 code running
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;;
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KeJumpToUserspace:
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; rdi = user args
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; rsi = entry point in user space
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; rdx = user space stack
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; Build a fake iret frame
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push QWORD 0x23 ; Selector 0x20 (User Data) + RPL 3
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push rdx ; User space stack
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push QWORD 0x202 ; rflags = interrupt enable + reserved bit
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push QWORD 0x1B ; Selector 0x18 (User Code) + RPL 3
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push rsi ; Entry point in user space
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iretq
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;;
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;; Syscall trigger
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;;
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KeSyscall:
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int 0x80
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ret
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