Re: More corrections to patch for irqtab.c

[ht-lab <hans64@ht-lab.com>]

Hi Juan,

Thanks for the patches, it is good to know that ELKS is not completely 
abandoned.....

Hans
www.ht-lab.com

On 02/02/2012 23:31, Juan Perez-Sanchez wrote:
> Hi,
>
>       I'm very sorry for this, but there are problems with the previous
> patch for irqtab.c.
> Please ignore the 2 previous patches. Next is the final, thoroughly
> tested patch for that file.
>
> Greetings,
>
> Juan
>
> diff -Nurb elks.orig/arch/i86/kernel/irqtab.c elks/arch/i86/kernel/irqtab.c
> --- elks.orig/arch/i86/kernel/irqtab.c	2002-10-31 19:04:25.000000000 -0600
> +++ elks/arch/i86/kernel/irqtab.c	2012-02-02 18:22:39.000000000 -0600
> @@ -36,6 +36,11 @@
>      #define bios_call_cnt    cseg_bios_call_cnt
>   #endif
>
> +#ifdef CONFIG_ROMCODE
> + #define SEG_IRQ_DATA es
> +#else
> + #define SEG_IRQ_DATA cs
> +#endif
>
>   #ifndef S_SPLINT_S
>   #asm
> @@ -105,27 +110,27 @@
>           mov dx,ds      ;the original value
>           cli            ;just here
>
> -        xor ax,ax
> -        mov es,ax      ;intr table
> -
>   #ifdef CONFIG_ROMCODE
>           mov ax,#CONFIG_ROM_IRQ_DATA
> -#else
> -        mov ax,cs
> +        mov es,ax
>   #endif
> -        mov ds,ax
>
> -	mov stashed_ds,dx
> +        seg SEG_IRQ_DATA
> +	mov stashed_ds,ds
> +	mov bios_call_cnt_l,#5
> +
> +        xor ax,ax
> +        mov es,ax      ;intr table
>
>   	seg es                     ;insert new timer intr
>   	mov bx,[32]
> -	mov off_stashed_irq0, bx   ; the old one
> +	mov off_stashed_irq0_l, bx   ; the old one
>   	lea ax,_irq0
>   	seg es
>   	mov [32],ax
>   	seg es
>   	mov bx,[34]
> -	mov seg_stashed_irq0, bx
> +	mov seg_stashed_irq0_l, bx
>   	mov ax,cs
>   	seg es
>   	mov [34],ax
> @@ -430,7 +435,7 @@
>   !	Save all registers
>   !
>
> -	cli		! Might not be disabled on an exception
> +!	cli		! Might not be disabled on an exception
>   	push	ds
>   	push	es
>   	push	bx
> @@ -445,23 +450,19 @@
>   !
>   #ifdef CONFIG_ROMCODE
>           mov bx,#CONFIG_ROM_IRQ_DATA
> -#else
> -        mov bx,cs
> +        mov es,bx
>   #endif
> -        mov ds,bx
> -
> -	mov	stashed_irq,ax	! Save IRQ number
> -	mov	ax,ss		! Get current SS
> -	mov	bx,ax		! Save for later
> -	mov	stashed_ss, ax	! Save SS:SP
> -	mov	ax,sp
> -	mov	stashed_sp, ax
>   !
>   !	Switch segments
>   !
> -	mov	ax,stashed_ds   ! Recover the data segment
> -	mov	ds,ax
> -	mov	es,ax
> +        seg SEG_IRQ_DATA
> +	mov	bx,stashed_ds		! Recover the data segment
> +	mov	ds,bx
> +	mov	es,bx
> +
> +	mov	dx,ss			! Get current SS
> +	mov	bp,sp			! Get current SP
> +	movb	cl,bios_call_cnt_l
>   !
>   !	Set up task switch controller
>   !
> @@ -469,14 +470,13 @@
>   !
>   !	See where we were (BX holds the SS on entry)
>   !
> -	cmp	ax,bx		! SS = kernel SS ?
> +	cmp	dx,bx		! SS = kernel SS ?
>   	je	ktask		! Kernel - no work
>   !
>   !	User or BIOS etc
>   !
> -	mov	ax,bx
>   	mov	bx,_current
> -	cmp	ax,4[bx]	! entry ss = current->t_regs.ss?
> +	cmp	dx,4[bx]	! entry ss = current->t_regs.ss?
>   	je	utask		! Switch to kernel
>   !
>   !	Bios etc - switch to interrupt stack
> @@ -488,37 +488,23 @@
>   !	User task. Extract kernel SP. (BX already holds current)
>   !
>   utask:
> -	mov	ax,[bx]		! kernel stack ptr
> -	mov	sp,ax		! switch to kernel stack
> +	mov	sp,[bx]		! switch to kernel stack ptr
>   	inc	ch		! Switch allowable
> -	j	switched
> -ktask:
>   !
>   !	In ktask state we have a suitable stack. It might be
>   !	better to use the intstack..
>   !
>   switched:
> -	mov	ax,ds
> -	mov	ss,ax		! /* Set SS: right */
> +	mov	bx,ds
> +	mov	ss,bx		! /* Set SS: right */
> +ktask:
>   ! /*
>   !	Put the old SS;SP on the top of the stack. We can't
>   !	leave them in stashed_ss/sp as we could re-enter the
>   !	routine on a reschedule.
>   ! */
> -#ifdef CONFIG_ROMCODE
> -        mov ax,#CONFIG_ROM_IRQ_DATA
> -        mov es,ax
> -        seg es
> -	push	stashed_sp
> -	seg es
> -	push	stashed_ss
> -
> -#else
> -	seg 	cs
> -	push	stashed_sp
> -	seg	cs
> -	push	stashed_ss
> -#endif
> +	push	bp		! push entry SP
> +	push	dx		! push entry SS
>   !
>   !	We are on a suitable stack and cx says whether we can
>   !	switch afterwards. The C code will want to eat CX so
> @@ -530,19 +516,9 @@
>   	mov	bp,sp
>   	mov	_can_tswitch, ch
>   	push	cx		! Save ch
> -#ifdef CONFIG_ROMCODE
> -        seg	es
> -#else
> -	seg	cs		! Recover the IRQ we saved
> -#endif
> -	mov	ax,stashed_irq
>   	push	ax		! IRQ for later
>   	push	bp		! Register base
>   	push	ax		! IRQ number
> -#ifdef CONFIG_ROMCODE
> -        mov ax,ds
> -        mov es,ax        ;es back to dataseg
> -#endif
>   !
>   !	Call the C code
>   !
> @@ -557,48 +533,22 @@
>   !
>   !	Restore any chips
>   !
> -	cmp	ax,#15
> +	cmp	ax,#16
>   	jge	was_trap	! Traps need no reset
> -	cmp	ax,#8
> -	jge	sec_8259	! IRQ on low chip
> -!
> -!	Reset primary 8259
> -!
> +	or	ax,ax		! Is int #0?
> +	jnz	a4
> +	dec	cl		! Will call bios int?
> +	je	was_trap
> +a4:
>   	mov	cl,al		! Save the IRQ number
> -	inb	al,0x21		! The chip line state
> -	jmp	a7
> -a7:	jmp	a8
> -a8:
> -!	movb	al,#1
> -!	shl	al,cl		! Shift the irq (saved in cl) to a mask
> -!	orb	al,_cache_21
> -!	movb	_cache_21, al
> -	movb	al,_cache_21	! Extract the IRQ mask register
> -	outb	0x21,al		! Now ack the IRQ
> -	jmp	a9
> -a9:	jmp	a10
> -a10:	movb	al,#0x20	! EOI
> -	outb	0x20,al
> -	jmp	was_trap
> -
> +	movb	al,#0x20	! EOI
> +	cmp	cl,#8
> +	jb	a6		! IRQ on low chip
>   !
>   !	Reset secondary 8259 if we have taken an AT rather
>   !	than XT irq. We also have to prod the primay
>   !	controller EOI..
>   !
> -sec_8259:
> -	mov	cl,al		! Save the IRQ for making masks
> -	inb	al,0xA1
> -	jmp	a1
> -a1:	jmp	a2
> -a2:	movb	al,#1
> -	shl	al,cl
> -	orb	al,_cache_A1
> -	movb	_cache_A1, al
> -	outb	0xA1,al		! Now ack the IRQ
> -	jmp	a3
> -a3:	jmp	a4
> -a4:	movb	al,#0x20
>   	outb	0xA0,al
>   	jmp	a5
>   a5:	jmp	a6
> @@ -609,6 +559,17 @@
>   !
>
>   was_trap:
> +	orb	cl,cl
> +	jnz	no_bios_call
> +!
> +!	IRQ 0 (timer) has to go on to the bios for some systems
> +!
> +	dec	bios_call_cnt_l
> +	jne	no_bios_call
> +	mov	bios_call_cnt_l,#5
> +	pushf
> +	callf	[off_stashed_irq0_l]
> +no_bios_call:
>   !
>   !	Now look at rescheduling
>   !
> @@ -655,83 +616,25 @@
>   	pop	cx
>   	pop	bx
>   	pop	es
> -#ifdef CONFIG_ROMCODE
> -	mov	ax,#CONFIG_ROM_IRQ_DATA
> -	mov	ds,ax
> -#else
> -	seg	cs
> -#endif
> -	mov	ax, stashed_irq
> -	or 	ax,ax
> -	jz	irq0_bios
>   	pop	ds
>   	pop	ax
>   !
>   !	Iret restores CS:IP and F (thus including the interrupt bit)
>   !
>   	iret
> -!
> -!	IRQ 0 (timer) has to go on to the bios for some systems
> -!
> -!	FIXME: should call the bios only every fifth event.
> -!
> -irq0_bios:
> -    pop     ds
> -	pop	ax           ;now the stack empty
> -
> -;------------------------------------------------
> -;Build new Stack
> -;
> -;  SP    ->   RET seg
> -;            RET offs
> -;  SP-4  ->   BP
> -;  SP-4  ->   BX
> -;            DS
> -;  SP-8  ->   free                     ;sp
> -
> -label1:
> -
> -	sub sp,#4                     ;space for retf
> -	push bp
> -	mov bp,sp
> -
> -	push	bx
> -	push    ds
> -#ifdef CONFIG_ROMCODE
> -	mov bx,#CONFIG_ROM_IRQ_DATA
> -#else
> -	mov bx,cs
> -#endif
> -	mov ds,bx
> -	mov	bx,bios_call_cnt
> -	inc	bx
> -	cmp	bx,#5
> -	jne	no_bios_call
> -
> -	xor	bx,bx
> -	mov	bios_call_cnt,bx
> -	mov bx, seg_stashed_irq0
> -	mov	[bp+4], bx
> -	mov bx, off_stashed_irq0
> -	mov [bp+2], bx
> -
> -	pop ds
> -	pop	bx
> -	pop bp
> -	retf
> -
> -no_bios_call:                          ;sp-8
> -	mov	bios_call_cnt,bx
> -	pop	ds
> -	pop	bx                     ;sp-4
> -	pop bp
> -	add sp,#4
> -	iret
>
>   	.data
>   .globl	_can_tswitch
>   _can_tswitch:
>   	.byte 0
> +
> +off_stashed_irq0_l:
> +	.word	0
> +seg_stashed_irq0_l:
> +	.word	0
> +bios_call_cnt_l:
> +	.word	0
> +
>   	.zerow	256		! (was) 128 byte interrupt stack
>   _intstack:
> --
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