216 lines
3.9 KiB
Plaintext
216 lines
3.9 KiB
Plaintext
; The OS/K Team licenses this file to you under the MIT license.
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; See the LICENSE file in the project root for more information.
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TrapHandlers.prolog:
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nul rbp
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; rax = caller's cr1
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call RFS.LoadReg, r14, $cr1
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; we don't preserve the r12 we got
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mov r12, rax
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nul rdx
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jmp rcx
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TrapHandlers.epilog:
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; TRAP return values: RAX-RDX
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mov ax2, rax
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call RFS.StoreReg, r14, $rax
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mov ax2, rdx
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call RFS.StoreReg, r14, $rdx
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call IDT.DoneHandling, r13
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iret
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;
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; TRAP #0 handler
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;
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DefaultTrapHandler:
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.init:
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mov rcx, .text
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mov rsp, TRAP0_STACK
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jmp TrapHandlers.prolog
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.text:
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call RFS.LoadReg, r14, $rax
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call RFS.LoadArgs, r14
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; will be optimized with a table
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; when we have a "finished" consistent API
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jraxz .handle_Shutdown
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beq rax, Sys.Exit, .handle_Exit
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beq rax, Sys.ExecuteInFrame, .handle_EIF
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beq rax, Sys.ReadFile, .handle_ReadFile
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beq rax, Sys.OpenFile, .handle_OpenFile
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beq rax, Sys.CloseFile, .handle_CloseFile
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beq rax, Sys.CreateFile, .handle_CreateFile
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beq rax, Sys.RemoveFile, .handle_RemoveFile
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beq rax, Sys.FindNext, .handle_FindNext
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beq rax, Sys.FindFirst, .handle_FindFirst
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beq rax, Sys.EnterHaltMode, .handle_HaltMode
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.sod:
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call ScreenOfDeath, .badsyscall, r13
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.wrong:
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call ScreenOfDeath, .badparams, r13
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.fini.savecx:
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mov ax2, rcx
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call RFS.StoreReg, r14, $rcx
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.fini:
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jmp TrapHandlers.epilog
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.badsyscall = "Invalid syscall number in RAX"
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.badparams = "Invalid syscall parameters"
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;------------------------------------------------;
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; Syscall implementations ;
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;------------------------------------------------;
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;
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; Pass control to COMMAND.COM in frame 0
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;
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.handle_Exit:
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; deactivate current rframe
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bzr r14, .hE_nz ; unless it's 0...
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call RFS.DeactivateFrame, r14
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.hE_nz:
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; open COMMAND.COM
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call DISK.OpenFile, .cmdcom
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; crash on failure
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bltz rax, abort
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; load at CMDCOM_LOADP
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mov ax1, CMDCOM_LOADP
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mov ax2, CMDCOM_MAXSZ
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call DISK.ReadFile, rax
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; assume that COMMAND.COM being
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; less then 4KB means something
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; went wrong
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blt rax, 0x1000, abort
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; close the handle
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call DISK.CloseFile, rax
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; code address
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mov ax2, 0x100000
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call RFS.StoreReg, zero, $rip
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; usermode
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mov ax2, 3
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call RFS.StoreReg, zero, $cr0
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mov rcx, CMDCOM_LOADP
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sub rcx, 0x100000
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; code offset
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mov ax2, rcx
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call RFS.StoreReg, zero, $cr1
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; return frame
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nul r14
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jmp .fini
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.cmdcom = "command.com"
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.handle_EIF:
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blt ax1, 5, .wrong
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; RIP can't be <1MB
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mov rcx, 0x100000
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blt ax0, rcx, .wrong
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; add old CR1
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add ax0, r12
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; real RIP can't be <1MB+32KB either
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; (kernel + cmdcom personal space)
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add rdx, rcx, 0x8000
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blt ax0, rcx, .wrong
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; save rframe and compute new CR1
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mov rbx, ax1
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sub rdi, ax0, rcx
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; activate rframe
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call RFS.ActivateFrame, rbx
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; save new CR1
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mov ax2, rdi
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call RFS.StoreReg, rbx, $cr1
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; interruptible user mode
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mov ax2, 3
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call RFS.StoreReg, rbx, $cr0
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; set RIP = 1MB
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mov ax2, rcx
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call RFS.StoreReg, rbx, $rip
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; change return frame
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mov r14, rbx
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jmp .fini
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;
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; Disk API
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;
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.handle_FindFirst:
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inc ax0, r12
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call DISK.FindFirst
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jmp .fini.savecx
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.handle_FindNext:
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inc ax0, r12
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call DISK.FindNext
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jmp .fini.savecx
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.handle_OpenFile:
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inc ax0, r12
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call DISK.OpenFile
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jmp .fini
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.handle_CreateFile:
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inc ax0, r12
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call DISK.CreateFile
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jmp .fini
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.handle_RemoveFile:
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inc ax0, r12
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call DISK.RemoveFile
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jmp .fini
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.handle_CloseFile:
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call DISK.CloseFile
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jmp .fini
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.handle_ReadFile:
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inc ax1, r12
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call DISK.ReadFile
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jmp .fini
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;
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; Misc.
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;
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.handle_Shutdown:
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call IDT.DelHandler, zero
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stop
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.handle_HaltMode:
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pause
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pause
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hlt
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jmp .handle_HaltMode
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