ad4dcaab71
- idle task becomes a pseudo task which is never scheduled. It is never put on any run queue and never enters userspace. An entry for this task still remains in the process table for time accounting - Instead of panicing if there is not process to schedule, pick_proc() returns NULL which is a signal to put the cpu in an idle state and set everything in such a way that after receiving and interrupt it looks like idle task was preempted - idle task is set non-preemptible to avoid handling in the timer interrupt code which make userspace scheduling simpler as idle task does not need to be handled as a special case.
575 lines
14 KiB
ArmAsm
575 lines
14 KiB
ArmAsm
/* sections */
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.text; .data; .data; .bss
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#include <minix/config.h>
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#include <minix/const.h>
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#include <ibm/interrupt.h>
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#include <archconst.h>
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#include "../../const.h"
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#include "sconst.h"
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/*
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* This file contains a number of assembly code utility routines needed by the
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* kernel. They are:
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*/
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.globl monitor /* exit Minix and return to the monitor */
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.globl int86 /* let the monitor make an 8086 interrupt call */
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.globl exit /* dummy for library routines */
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.globl _exit /* dummy for library routines */
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.globl __exit /* dummy for library routines */
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.globl __main /* dummy for GCC */
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.globl phys_insw /* transfer data from (disk controller) port to memory */
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.globl phys_insb /* likewise byte by byte */
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.globl phys_outsw /* transfer data from memory to (disk controller) port */
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.globl phys_outsb /* likewise byte by byte */
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.globl phys_copy /* copy data from anywhere to anywhere in memory */
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.globl phys_copy_fault /* phys_copy pagefault */
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.globl phys_copy_fault_in_kernel /* phys_copy pagefault in kernel */
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.globl phys_memset /* write pattern anywhere in memory */
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.globl mem_rdw /* copy one word from [segment:offset] */
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.globl reset /* reset the system */
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.globl halt_cpu/* halts the current cpu when idle */
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.globl level0 /* call a function at level 0 */
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.globl read_cpu_flags /* read the cpu flags */
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.globl read_cr0 /* read cr0 */
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.globl read_cr2 /* read cr2 */
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.globl getcr3val
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.globl write_cr0 /* write a value in cr0 */
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.globl read_cr4
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.globl thecr3
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.globl write_cr4
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.globl catch_pagefaults
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.globl read_ds
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.globl read_cs
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.globl read_ss
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/*
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* The routines only guarantee to preserve the registers the C compiler
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* expects to be preserved (ebx, esi, edi, ebp, esp, segment registers, and
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* direction bit in the flags).
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*/
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.text
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/*===========================================================================*/
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/* monitor */
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/*===========================================================================*/
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/* PUBLIC void monitor(); */
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/* Return to the monitor. */
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monitor:
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movl mon_sp, %esp /* restore monitor stack pointer */
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movw $SS_SELECTOR, %dx /* monitor data segment */
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mov %dx, %ds
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mov %dx, %es
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mov %dx, %fs
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mov %dx, %gs
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mov %dx, %ss
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pop %edi
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pop %esi
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pop %ebp
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lretw /* return to the monitor */
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/*===========================================================================*/
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/* int86 */
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/*===========================================================================*/
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/* PUBLIC void int86(); */
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int86:
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cmpb $0, mon_return /* is the monitor there? */
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jne 0f
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movb $0x01, %ah /* an int 13 error seems appropriate */
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movb %ah, reg86+0 /* reg86.w.f = 1 (set carry flag) */
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movb %ah, reg86+13 /* reg86.b.ah = 0x01 = "invalid command" */
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ret
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0:
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push %ebp /* save C registers */
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push %esi
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push %edi
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push %ebx
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pushf /* save flags */
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cli /* no interruptions */
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inb $INT2_CTLMASK
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movb %al, %ah
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inb $INT_CTLMASK
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push %eax /* save interrupt masks */
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movl irq_use, %eax /* map of in-use IRQ's */
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and $~(1<<CLOCK_IRQ), %eax /* keep the clock ticking */
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outb $INT_CTLMASK /* enable all unused IRQ's and vv. */
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movb %ah, %al
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outb $INT2_CTLMASK
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mov $SS_SELECTOR, %eax /* monitor data segment */
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mov %ax, %ss
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xchgl mon_sp, %esp /* switch stacks */
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push reg86+36 /* parameters used in INT call */
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push reg86+32
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push reg86+28
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push reg86+24
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push reg86+20
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push reg86+16
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push reg86+12
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push reg86+8
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push reg86+4
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push reg86+0
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mov %ax, %ds /* remaining data selectors */
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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push %cs
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push $return /* kernel return address and selector */
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ljmpw *20+2*4+10*4+2*4(%esp)
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return:
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pop reg86+0
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pop reg86+4
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pop reg86+8
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pop reg86+12
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pop reg86+16
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pop reg86+20
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pop reg86+24
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pop reg86+28
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pop reg86+32
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pop reg86+36
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lgdt gdt+GDT_SELECTOR /* reload global descriptor table */
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ljmp $CS_SELECTOR, $csinit
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csinit:
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mov $DS_SELECTOR, %eax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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mov %ax, %ss
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xchgl mon_sp, %esp /* unswitch stacks */
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lidt gdt+IDT_SELECTOR /* reload interrupt descriptor table */
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andb $~0x02, gdt+TSS_SELECTOR+DESC_ACCESS /* clear TSS busy bit */
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mov $TSS_SELECTOR, %eax
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ltr %ax /* set TSS register */
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pop %eax
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outb $INT_CTLMASK /* restore interrupt masks */
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movb %ah, %al
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outb $INT2_CTLMASK
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addl %ecx, lost_ticks /* record lost clock ticks */
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popf /* restore flags */
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pop %ebx /* restore C registers */
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pop %edi
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pop %esi
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pop %ebp
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ret
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/*===========================================================================*/
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/* exit */
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/*===========================================================================*/
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/*
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* PUBLIC void exit();
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* Some library routines use exit, so provide a dummy version.
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* Actual calls to exit cannot occur in the kernel.
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* GNU CC likes to call ___main from main() for nonobvious reasons.
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*/
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exit:
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_exit:
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__exit:
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sti
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jmp __exit
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__main:
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ret
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/*===========================================================================*/
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/* phys_insw */
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/*===========================================================================*/
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/*
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* PUBLIC void phys_insw(Port_t port, phys_bytes buf, size_t count);
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* Input an array from an I/O port. Absolute address version of insw().
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*/
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phys_insw:
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push %ebp
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mov %esp, %ebp
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cld
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push %edi
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push %es
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mov $FLAT_DS_SELECTOR, %ecx
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mov %cx, %es
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mov 8(%ebp), %edx /* port to read from */
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mov 12(%ebp), %edi /* destination addr */
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mov 16(%ebp), %ecx /* byte count */
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shr $1, %ecx /* word count */
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rep insw /* input many words */
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pop %es
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pop %edi
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pop %ebp
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ret
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/*===========================================================================*/
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/* phys_insb */
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/*===========================================================================*/
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/*
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* PUBLIC void phys_insb(Port_t port, phys_bytes buf, size_t count);
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* Input an array from an I/O port. Absolute address version of insb().
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*/
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phys_insb:
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push %ebp
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mov %esp, %ebp
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cld
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push %edi
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push %es
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mov $FLAT_DS_SELECTOR, %ecx
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mov %cx, %es
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mov 8(%ebp), %edx /* port to read from */
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mov 12(%ebp), %edi /* destination addr */
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mov 16(%ebp), %ecx /* byte count */
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rep insb /* input many bytes */
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pop %es
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pop %edi
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pop %ebp
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ret
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/*===========================================================================*/
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/* phys_outsw */
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/*===========================================================================*/
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/*
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* PUBLIC void phys_outsw(Port_t port, phys_bytes buf, size_t count);
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* Output an array to an I/O port. Absolute address version of outsw().
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*/
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.balign 16
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phys_outsw:
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push %ebp
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mov %esp, %ebp
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cld
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push %esi
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push %ds
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mov $FLAT_DS_SELECTOR, %ecx
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mov %cx, %ds
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mov 8(%ebp), %edx /* port to write to */
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mov 12(%ebp), %esi /* source addr */
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mov 16(%ebp), %ecx /* byte count */
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shr $1, %ecx /* word count */
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rep outsw /* output many words */
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pop %ds
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pop %esi
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pop %ebp
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ret
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/*===========================================================================*/
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/* phys_outsb */
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/*===========================================================================*/
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/*
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* PUBLIC void phys_outsb(Port_t port, phys_bytes buf, size_t count);
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* Output an array to an I/O port. Absolute address version of outsb().
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*/
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.balign 16
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phys_outsb:
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push %ebp
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mov %esp, %ebp
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cld
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push %esi
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push %ds
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mov $FLAT_DS_SELECTOR, %ecx
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mov %cx, %ds
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mov 8(%ebp), %edx /* port to write to */
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mov 12(%ebp), %esi /* source addr */
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mov 16(%ebp), %ecx /* byte count */
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rep outsb /* output many bytes */
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pop %ds
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pop %esi
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pop %ebp
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ret
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/*===========================================================================*/
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/* phys_copy */
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/*===========================================================================*/
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/*
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* PUBLIC phys_bytes phys_copy(phys_bytes source, phys_bytes destination,
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* phys_bytes bytecount);
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* Copy a block of physical memory.
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*/
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PC_ARGS = 4+4+4+4 /* 4 + 4 + 4 */
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/* es edi esi eip src dst len */
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.balign 16
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phys_copy:
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cld
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push %esi
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push %edi
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push %es
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mov $FLAT_DS_SELECTOR, %eax
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mov %ax, %es
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mov PC_ARGS(%esp), %esi
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mov PC_ARGS+4(%esp), %edi
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mov PC_ARGS+4+4(%esp), %eax
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cmp $10, %eax /* avoid align overhead for small counts */
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jb pc_small
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mov %esi, %ecx /* align source, hope target is too */
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neg %ecx
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and $3, %ecx /* count for alignment */
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sub %ecx, %eax
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rep movsb %es:(%esi), %es:(%edi)
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mov %eax, %ecx
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shr $2, %ecx /* count of dwords */
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rep movsl %es:(%esi), %es:(%edi)
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and $3, %eax
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pc_small:
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xchg %eax, %ecx /* remainder */
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rep movsb %es:(%esi), %es:(%edi)
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mov $0, %eax /* 0 means: no fault */
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phys_copy_fault: /* kernel can send us here */
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pop %es
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pop %edi
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pop %esi
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ret
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phys_copy_fault_in_kernel: /* kernel can send us here */
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pop %es
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pop %edi
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pop %esi
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mov %cr2, %eax
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ret
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/*===========================================================================*/
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/* phys_memset */
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/*===========================================================================*/
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/*
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* PUBLIC void phys_memset(phys_bytes source, unsigned long pattern,
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* phys_bytes bytecount);
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* Fill a block of physical memory with pattern.
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*/
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.balign 16
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phys_memset:
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push %ebp
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mov %esp, %ebp
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push %esi
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push %ebx
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push %ds
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mov 8(%ebp), %esi
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mov 16(%ebp), %eax
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mov $FLAT_DS_SELECTOR, %ebx
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mov %bx, %ds
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mov 12(%ebp), %ebx
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shr $2, %eax
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fill_start:
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mov %ebx, (%esi)
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add $4, %esi
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dec %eax
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jne fill_start
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/* Any remaining bytes? */
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mov 16(%ebp), %eax
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and $3, %eax
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remain_fill:
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cmp $0, %eax
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je fill_done
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movb 12(%ebp), %bl
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movb %bl, (%esi)
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add $1, %esi
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inc %ebp
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dec %eax
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jmp remain_fill
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fill_done:
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pop %ds
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pop %ebx
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pop %esi
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pop %ebp
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ret
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/*===========================================================================*/
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/* mem_rdw */
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/*===========================================================================*/
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/*
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* PUBLIC u16_t mem_rdw(U16_t segment, u16_t *offset);
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* Load and return word at far pointer segment:offset.
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*/
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.balign 16
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mem_rdw:
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mov %ds, %cx
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mov 4(%esp), %ds
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mov 4+4(%esp), %eax /* offset */
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movzwl (%eax), %eax /* word to return */
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mov %cx, %ds
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ret
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/*===========================================================================*/
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/* reset */
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/*===========================================================================*/
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/*
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* PUBLIC void reset();
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* Reset the system by loading IDT with offset 0 and interrupting.
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*/
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reset:
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lidt idt_zero
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int $3 /* anything goes, the 386 will not like it */
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.data
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idt_zero:
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.long 0, 0
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.text
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/*===========================================================================*/
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/* halt_cpu */
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/*===========================================================================*/
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/*
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* PUBLIC void halt_cpu(void);
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* reanables interrupts and puts the cpu in the halts state. Once an interrupt
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* is handled the execution resumes by disabling interrupts and continues
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*/
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halt_cpu:
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sti
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hlt
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cli
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ret
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/*===========================================================================*/
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/* level0 */
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/*===========================================================================*/
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/*
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* PUBLIC void level0(void (*func)(void))
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* Call a function at permission level 0. This allows kernel tasks to do
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* things that are only possible at the most privileged CPU level.
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*/
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level0:
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/* check whether we are already running in kernel, the kernel cs
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* selector has 3 lower bits zeroed */
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mov %cs, %ax
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cmpw $CS_SELECTOR, %ax
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jne 0f
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/* call the function directly as if it was a normal function call */
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mov 4(%esp), %eax
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call *%eax
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ret
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/* if not runnig in the kernel yet, trap to kernel */
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0:
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mov 4(%esp), %eax
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int $LEVEL0_VECTOR
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ret
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/*===========================================================================*/
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/* read_flags */
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/*===========================================================================*/
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/*
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* PUBLIC unsigned long read_cpu_flags(void);
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* Read CPU status flags from C.
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*/
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.balign 16
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read_cpu_flags:
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pushf
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mov (%esp), %eax
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popf
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ret
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read_ds:
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mov $0, %eax
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mov %ds, %ax
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ret
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read_cs:
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mov $0, %eax
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mov %cs, %ax
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ret
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read_ss:
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mov $0, %eax
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mov %ss, %ax
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ret
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/*===========================================================================*/
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/* read_cr0 */
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/*===========================================================================*/
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/* PUBLIC unsigned long read_cr0(void); */
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read_cr0:
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push %ebp
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mov %esp, %ebp
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mov %cr0, %eax
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pop %ebp
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ret
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/*===========================================================================*/
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/* write_cr0 */
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/*===========================================================================*/
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/* PUBLIC void write_cr0(unsigned long value); */
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write_cr0:
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %eax
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mov %eax, %cr0
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jmp 0f /* A jump is required for some flags */
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0:
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pop %ebp
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ret
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/*===========================================================================*/
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/* read_cr2 */
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/*===========================================================================*/
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/* PUBLIC reg_t read_cr2(void); */
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read_cr2:
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mov %cr2, %eax
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ret
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/*===========================================================================*/
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/* read_cr4 */
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/*===========================================================================*/
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/* PUBLIC unsigned long read_cr4(void); */
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read_cr4:
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push %ebp
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mov %esp, %ebp
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mov %cr4, %eax
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pop %ebp
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ret
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/*===========================================================================*/
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/* write_cr4 */
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/*===========================================================================*/
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/* PUBLIC void write_cr4(unsigned long value); */
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write_cr4:
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %eax
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mov %eax, %cr4
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jmp 0f
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0:
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pop %ebp
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ret
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/*===========================================================================*/
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/* getcr3val */
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/*===========================================================================*/
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/* PUBLIC unsigned long getcr3val(void); */
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getcr3val:
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mov %cr3, %eax
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mov %eax, thecr3
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ret
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