536 lines
16 KiB
ArmAsm
Executable file
536 lines
16 KiB
ArmAsm
Executable file
#
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! This file, mpx386.s, is included by mpx.s when Minix is compiled for
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! 32-bit Intel CPUs. The alternative mpx88.s is compiled for 16-bit CPUs.
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! This file is part of the lowest layer of the MINIX kernel. (The other part
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! is "proc.c".) The lowest layer does process switching and message handling.
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! Furthermore it contains the assembler startup code for Minix and the 32-bit
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! interrupt handlers. It cooperates with the code in "start.c" to set up a
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! good environment for main().
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! Every transition to the kernel goes through this file. Transitions to the
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! kernel may be nested. The initial entry may be with a system call (i.e.,
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! send or receive a message), an exception or a hardware interrupt; kernel
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! reentries may only be made by hardware interrupts. The count of reentries
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! is kept in "k_reenter". It is important for deciding whether to switch to
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! the kernel stack and for protecting the message passing code in "proc.c".
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! For the message passing trap, most of the machine state is saved in the
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! proc table. (Some of the registers need not be saved.) Then the stack is
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! switched to "k_stack", and interrupts are reenabled. Finally, the system
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! call handler (in C) is called. When it returns, interrupts are disabled
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! again and the code falls into the restart routine, to finish off held-up
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! interrupts and run the process or task whose pointer is in "proc_ptr".
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! Hardware interrupt handlers do the same, except (1) The entire state must
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! be saved. (2) There are too many handlers to do this inline, so the save
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! routine is called. A few cycles are saved by pushing the address of the
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! appropiate restart routine for a return later. (3) A stack switch is
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! avoided when the stack is already switched. (4) The (master) 8259 interrupt
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! controller is reenabled centrally in save(). (5) Each interrupt handler
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! masks its interrupt line using the 8259 before enabling (other unmasked)
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! interrupts, and unmasks it after servicing the interrupt. This limits the
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! nest level to the number of lines and protects the handler from itself.
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! For communication with the boot monitor at startup time some constant
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! data are compiled into the beginning of the text segment. This facilitates
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! reading the data at the start of the boot process, since only the first
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! sector of the file needs to be read.
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! Some data storage is also allocated at the end of this file. This data
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! will be at the start of the data segment of the kernel and will be read
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! and modified by the boot monitor before the kernel starts.
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! sections
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.sect .text
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begtext:
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.sect .rom
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begrom:
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.sect .data
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begdata:
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.sect .bss
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begbss:
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#include <minix/config.h>
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#include <minix/const.h>
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#include <minix/com.h>
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#include <ibm/interrupt.h>
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#include "const.h"
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#include "protect.h"
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#include "sconst.h"
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/* Selected 386 tss offsets. */
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#define TSS3_S_SP0 4
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! Exported functions
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! Note: in assembly language the .define statement applied to a function name
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! is loosely equivalent to a prototype in C code -- it makes it possible to
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! link to an entity declared in the assembly code but does not create
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! the entity.
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.define _restart
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.define save
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.define _divide_error
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.define _single_step_exception
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.define _nmi
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.define _breakpoint_exception
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.define _overflow
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.define _bounds_check
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.define _inval_opcode
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.define _copr_not_available
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.define _double_fault
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.define _copr_seg_overrun
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.define _inval_tss
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.define _segment_not_present
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.define _stack_exception
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.define _general_protection
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.define _page_fault
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.define _copr_error
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.define _hwint00 ! handlers for hardware interrupts
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.define _hwint01
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.define _hwint02
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.define _hwint03
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.define _hwint04
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.define _hwint05
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.define _hwint06
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.define _hwint07
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.define _hwint08
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.define _hwint09
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.define _hwint10
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.define _hwint11
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.define _hwint12
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.define _hwint13
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.define _hwint14
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.define _hwint15
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.define _s_call
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.define _p_s_call
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.define _level0_call
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! Exported variables.
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.define begbss
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.define begdata
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.sect .text
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!*===========================================================================*
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!* MINIX *
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!*===========================================================================*
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MINIX: ! this is the entry point for the MINIX kernel
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jmp over_flags ! skip over the next few bytes
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.data2 CLICK_SHIFT ! for the monitor: memory granularity
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flags:
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.data2 0x01FD ! boot monitor flags:
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! call in 386 mode, make bss, make stack,
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! load high, don't patch, will return,
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! uses generic INT, memory vector,
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! new boot code return
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nop ! extra byte to sync up disassembler
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over_flags:
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! Set up a C stack frame on the monitor stack. (The monitor sets cs and ds
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! right. The ss descriptor still references the monitor data segment.)
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movzx esp, sp ! monitor stack is a 16 bit stack
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push ebp
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mov ebp, esp
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push esi
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push edi
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cmp 4(ebp), 0 ! monitor return vector is
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jz noret ! nonzero if return possible
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inc (_mon_return)
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noret: mov (_mon_sp), esp ! save stack pointer for later return
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! Copy the monitor global descriptor table to the address space of kernel and
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! switch over to it. Prot_init() can then update it with immediate effect.
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sgdt (_gdt+GDT_SELECTOR) ! get the monitor gdtr
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mov esi, (_gdt+GDT_SELECTOR+2) ! absolute address of GDT
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mov ebx, _gdt ! address of kernel GDT
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mov ecx, 8*8 ! copying eight descriptors
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copygdt:
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eseg movb al, (esi)
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movb (ebx), al
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inc esi
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inc ebx
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loop copygdt
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mov eax, (_gdt+DS_SELECTOR+2) ! base of kernel data
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and eax, 0x00FFFFFF ! only 24 bits
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add eax, _gdt ! eax = vir2phys(gdt)
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mov (_gdt+GDT_SELECTOR+2), eax ! set base of GDT
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lgdt (_gdt+GDT_SELECTOR) ! switch over to kernel GDT
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! Locate boot parameters, set up kernel segment registers and stack.
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mov ebx, 8(ebp) ! boot parameters offset
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mov edx, 12(ebp) ! boot parameters length
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mov eax, 16(ebp) ! address of a.out headers
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mov (_aout), eax
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mov ax, ds ! kernel data
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov ss, ax
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mov esp, k_stktop ! set sp to point to the top of kernel stack
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! Call C startup code to set up a proper environment to run main().
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push edx
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push ebx
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push SS_SELECTOR
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push DS_SELECTOR
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push CS_SELECTOR
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call _cstart ! cstart(cs, ds, mds, parmoff, parmlen)
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add esp, 5*4
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! Reload gdtr, idtr and the segment registers to global descriptor table set
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! up by prot_init().
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lgdt (_gdt+GDT_SELECTOR)
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lidt (_gdt+IDT_SELECTOR)
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jmpf CS_SELECTOR:csinit
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csinit:
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o16 mov ax, DS_SELECTOR
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mov ds, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov ss, ax
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o16 mov ax, TSS_SELECTOR ! no other TSS is used
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ltr ax
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push 0 ! set flags to known good state
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popf ! esp, clear nested task and int enable
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jmp _main ! main()
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!*===========================================================================*
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!* interrupt handlers *
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!* interrupt handlers for 386 32-bit protected mode *
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!*===========================================================================*
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!*===========================================================================*
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!* hwint00 - 07 *
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!*===========================================================================*
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! Note this is a macro, it just looks like a subroutine.
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#define hwint_master(irq) \
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call save /* save interrupted process state */;\
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push (_irq_handlers+4*irq) /* irq_handlers[irq] */;\
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call _intr_handle /* intr_handle(irq_handlers[irq]) */;\
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pop ecx ;\
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cmp (_irq_actids+4*irq), 0 /* interrupt still active? */;\
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jz 0f ;\
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inb INT_CTLMASK /* get current mask */ ;\
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orb al, [1<<irq] /* mask irq */ ;\
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outb INT_CTLMASK /* disable the irq */;\
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0: movb al, END_OF_INT ;\
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outb INT_CTL /* reenable master 8259 */;\
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ret /* restart (another) process */
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! Each of these entry points is an expansion of the hwint_master macro
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.align 16
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_hwint00: ! Interrupt routine for irq 0 (the clock).
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hwint_master(0)
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.align 16
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_hwint01: ! Interrupt routine for irq 1 (keyboard)
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hwint_master(1)
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.align 16
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_hwint02: ! Interrupt routine for irq 2 (cascade!)
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hwint_master(2)
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.align 16
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_hwint03: ! Interrupt routine for irq 3 (second serial)
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hwint_master(3)
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.align 16
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_hwint04: ! Interrupt routine for irq 4 (first serial)
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hwint_master(4)
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.align 16
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_hwint05: ! Interrupt routine for irq 5 (XT winchester)
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hwint_master(5)
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.align 16
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_hwint06: ! Interrupt routine for irq 6 (floppy)
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hwint_master(6)
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.align 16
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_hwint07: ! Interrupt routine for irq 7 (printer)
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hwint_master(7)
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!*===========================================================================*
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!* hwint08 - 15 *
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!*===========================================================================*
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! Note this is a macro, it just looks like a subroutine.
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#define hwint_slave(irq) \
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call save /* save interrupted process state */;\
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push (_irq_handlers+4*irq) /* irq_handlers[irq] */;\
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call _intr_handle /* intr_handle(irq_handlers[irq]) */;\
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pop ecx ;\
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cmp (_irq_actids+4*irq), 0 /* interrupt still active? */;\
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jz 0f ;\
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inb INT2_CTLMASK ;\
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orb al, [1<<[irq-8]] ;\
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outb INT2_CTLMASK /* disable the irq */;\
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0: movb al, END_OF_INT ;\
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outb INT_CTL /* reenable master 8259 */;\
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outb INT2_CTL /* reenable slave 8259 */;\
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ret /* restart (another) process */
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! Each of these entry points is an expansion of the hwint_slave macro
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.align 16
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_hwint08: ! Interrupt routine for irq 8 (realtime clock)
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hwint_slave(8)
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.align 16
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_hwint09: ! Interrupt routine for irq 9 (irq 2 redirected)
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hwint_slave(9)
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.align 16
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_hwint10: ! Interrupt routine for irq 10
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hwint_slave(10)
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.align 16
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_hwint11: ! Interrupt routine for irq 11
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hwint_slave(11)
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.align 16
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_hwint12: ! Interrupt routine for irq 12
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hwint_slave(12)
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.align 16
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_hwint13: ! Interrupt routine for irq 13 (FPU exception)
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hwint_slave(13)
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.align 16
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_hwint14: ! Interrupt routine for irq 14 (AT winchester)
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hwint_slave(14)
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.align 16
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_hwint15: ! Interrupt routine for irq 15
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hwint_slave(15)
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!*===========================================================================*
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!* save *
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!*===========================================================================*
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! Save for protected mode.
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! This is much simpler than for 8086 mode, because the stack already points
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! into the process table, or has already been switched to the kernel stack.
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.align 16
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save:
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cld ! set direction flag to a known value
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pushad ! save "general" registers
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o16 push ds ! save ds
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o16 push es ! save es
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o16 push fs ! save fs
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o16 push gs ! save gs
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mov dx, ss ! ss is kernel data segment
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mov ds, dx ! load rest of kernel segments
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mov es, dx ! kernel does not use fs, gs
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mov eax, esp ! prepare to return
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incb (_k_reenter) ! from -1 if not reentering
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jnz set_restart1 ! stack is already kernel stack
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mov esp, k_stktop
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push _restart ! build return address for int handler
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xor ebp, ebp ! for stacktrace
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jmp RETADR-P_STACKBASE(eax)
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.align 4
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set_restart1:
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push restart1
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jmp RETADR-P_STACKBASE(eax)
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!*===========================================================================*
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!* _s_call *
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!*===========================================================================*
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.align 16
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_s_call:
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_p_s_call:
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cld ! set direction flag to a known value
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sub esp, 6*4 ! skip RETADR, eax, ecx, edx, ebx, est
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push ebp ! stack already points into proc table
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push esi
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push edi
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o16 push ds
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o16 push es
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o16 push fs
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o16 push gs
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mov si, ss ! ss is kernel data segment
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mov ds, si ! load rest of kernel segments
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mov es, si ! kernel does not use fs, gs
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incb (_k_reenter) ! increment kernel entry count
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mov esi, esp ! assumes P_STACKBASE == 0
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mov esp, k_stktop
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xor ebp, ebp ! for stacktrace
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! end of inline save
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! now set up parameters for sys_call()
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push edx ! event set or flags bit map
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push ebx ! pointer to user message
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push eax ! source / destination
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push ecx ! call number (ipc primitive to use)
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call _sys_call ! sys_call(call_nr, src_dst, m_ptr, bit_map)
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! caller is now explicitly in proc_ptr
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mov AXREG(esi), eax ! sys_call MUST PRESERVE si
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! Fall into code to restart proc/task running.
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!*===========================================================================*
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!* restart *
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!*===========================================================================*
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_restart:
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! Restart the current process or the next process if it is set.
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cmp (_next_ptr), 0 ! see if another process is scheduled
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jz 0f
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mov eax, (_next_ptr)
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mov (_proc_ptr), eax ! schedule new process
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mov (_next_ptr), 0
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0: mov esp, (_proc_ptr) ! will assume P_STACKBASE == 0
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lldt P_LDT_SEL(esp) ! enable process' segment descriptors
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lea eax, P_STACKTOP(esp) ! arrange for next interrupt
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mov (_tss+TSS3_S_SP0), eax ! to save state in process table
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restart1:
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decb (_k_reenter)
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o16 pop gs
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o16 pop fs
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o16 pop es
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o16 pop ds
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popad
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add esp, 4 ! skip return adr
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iretd ! continue process
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!*===========================================================================*
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!* exception handlers *
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!*===========================================================================*
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_divide_error:
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push DIVIDE_VECTOR
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jmp exception
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_single_step_exception:
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push DEBUG_VECTOR
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jmp exception
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_nmi:
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push NMI_VECTOR
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jmp exception
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_breakpoint_exception:
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push BREAKPOINT_VECTOR
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jmp exception
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_overflow:
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push OVERFLOW_VECTOR
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jmp exception
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_bounds_check:
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push BOUNDS_VECTOR
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jmp exception
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_inval_opcode:
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push INVAL_OP_VECTOR
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jmp exception
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_copr_not_available:
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push COPROC_NOT_VECTOR
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jmp exception
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_double_fault:
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push DOUBLE_FAULT_VECTOR
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jmp errexception
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_copr_seg_overrun:
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push COPROC_SEG_VECTOR
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jmp exception
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_inval_tss:
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push INVAL_TSS_VECTOR
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jmp errexception
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_segment_not_present:
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push SEG_NOT_VECTOR
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jmp errexception
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_stack_exception:
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push STACK_FAULT_VECTOR
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jmp errexception
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_general_protection:
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push PROTECTION_VECTOR
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jmp errexception
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_page_fault:
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push PAGE_FAULT_VECTOR
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jmp errexception
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_copr_error:
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push COPROC_ERR_VECTOR
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jmp exception
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!*===========================================================================*
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!* exception *
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!*===========================================================================*
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! This is called for all exceptions which do not push an error code.
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.align 16
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exception:
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sseg mov (trap_errno), 0 ! clear trap_errno
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sseg pop (ex_number)
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jmp exception1
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!*===========================================================================*
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!* errexception *
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!*===========================================================================*
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! This is called for all exceptions which push an error code.
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.align 16
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errexception:
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sseg pop (ex_number)
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sseg pop (trap_errno)
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exception1: ! Common for all exceptions.
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push eax ! eax is scratch register
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mov eax, 0+4(esp) ! old eip
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sseg mov (old_eip), eax
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movzx eax, 4+4(esp) ! old cs
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sseg mov (old_cs), eax
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mov eax, 8+4(esp) ! old eflags
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sseg mov (old_eflags), eax
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pop eax
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call save
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push (old_eflags)
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push (old_cs)
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push (old_eip)
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push (trap_errno)
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push (ex_number)
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call _exception ! (ex_number, trap_errno, old_eip,
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! old_cs, old_eflags)
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add esp, 5*4
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ret
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!*===========================================================================*
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!* level0_call *
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!*===========================================================================*
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_level0_call:
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call save
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jmp (_level0_func)
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!*===========================================================================*
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!* data *
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!*===========================================================================*
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.sect .rom ! Before the string table please
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.data2 0x526F ! this must be the first data entry (magic #)
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.sect .bss
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k_stack:
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.space K_STACK_BYTES ! kernel stack
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k_stktop: ! top of kernel stack
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.comm ex_number, 4
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.comm trap_errno, 4
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.comm old_eip, 4
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.comm old_cs, 4
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.comm old_eflags, 4
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