minix/kernel/arch/i386/klib386.S
Tomas Hruby ad4dcaab71 Idle task never runs
- 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.
2009-11-12 08:42:18 +00:00

574 lines
14 KiB
ArmAsm

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