powermac-rom/NanoKernel/NKExceptions.s

;	AUTO-GENERATED SYMBOL LIST

########################################################################
; MemRetry error
MRException
	mtsprg	3, r24

	lwz		r9, KDP.Enables(r1)
	extrwi	r23, r17, 5, 26					; extract accessLen field
	rlwnm.	r9, r9, r8, 0, 0				; BGE taken if exception disabled

	bcl		BO_IF, mrFlagDidLoad, LoadExtraMRRegs

	lwz		r6, KDP.ContextPtr(r1)

	_set	r7, r16, bitContextFlagMemRetryErr
	neg		r23, r23
	mtcrf	crMaskFlags, r7
	add		r19, r19, r23					; convert r19 from end address back to start address??
	insrwi	r7, r8, 8, 0					; ec code -> high byte of flags

	slwi	r8, r8, 2						; increment counter
	add		r8, r8, r1
	lwz		r9, KDP.NKInfo.ExceptionCauseCounts(r8)
	addi	r9, r9, 1
	stw		r9, KDP.NKInfo.ExceptionCauseCounts(r8)

	;	Move regs from KDP to ContextBlock
	lwz		r8, KDP.r7(r1)
	stw		r8, CB.r7+4(r6)
	lwz		r8, KDP.r8(r1)
	stw		r8, CB.r8+4(r6)
	lwz		r8, KDP.r9(r1)
	stw		r8, CB.r9+4(r6)
	lwz		r8, KDP.r10(r1)
	stw		r8, CB.r10+4(r6)
	lwz		r8, KDP.r11(r1)
	stw		r8, CB.r11+4(r6)
	lwz		r8, KDP.r12(r1)
	stw		r8, CB.r12+4(r6)
	lwz		r8, KDP.r13(r1)
	stw		r8, CB.r13+4(r6)

	bge		RunSystemContext				; Alt Context has left exception disabled => Sys Context
	;fall through							; exception enabled => run userspace handler

########################################################################
; Exception or MRException that is Enabled (i.e. not being auto-forced to System)
ExceptionCommon
	stw		r10, CB.FaultSrcPC+4(r6)			; Save r10/SRR0, r12/LR, r3, r4
	stw		r12, CB.FaultSrcLR+4(r6)
	stw		r3, CB.FaultSrcR3+4(r6)
	stw		r4, CB.FaultSrcR4+4(r6)

	lwz		r8, KDP.Enables(r1)						; Save Enables & Flags, inc ContextFlagMemRetryErr		
	stw		r7, CB.IntraState.Flags(r6)
	stw		r8, CB.IntraState.Enables(r6)

													; Use IntraState because context handles its own error
	li		r8, 0									; Enables=0 (any exceptions in handler go to System)
	lwz		r10, CB.IntraState.Handler+4(r6)		; SRR0 = handler addr
	lwz		r4, CB.IntraState.HandlerArg+4(r6)		; r4 = arbitrary second argument
	lwz		r3, KDP.ECBPtrLogical(r1)				; r3 = ContextBlock ptr
	bc		BO_IF, bitGlobalFlagSystem, @sys
	lwz		r3, KDP.NCBCacheLA0(r1)
@sys
	lwz		r12, KDP.EmuKCallTblPtrLogical(r1)		; r12/LR = address of KCallReturnFromException trap

	bcl		BO_IF, bitContextFlagMemRetryErr, SaveFailingMemRetryState

	rlwinm	r7, r7, 0, 29, 15						; unset flags 16-28
	stw		r8, KDP.Enables(r1)
	rlwimi	r11, r7, 0, 20, 23						; threfore unset MSR[FE0/SE/BE/FE1]

	b		ReturnFromInt

########################################################################

LoadExtraMRRegs
	lwz		r0, KDP.r0(r1)
	lwz		r2, KDP.r2(r1)
	lwz		r3, KDP.r3(r1)
	lwz		r4, KDP.r4(r1)
	lwz		r5, KDP.r5(r1)
	blr

SaveFailingMemRetryState
	stw		r17, CB.IntraState.MemRet17+4(r6)
	stw		r20, CB.IntraState.MemRetData(r6)
	stw		r21, CB.IntraState.MemRetData+4(r6)
	stw		r19, CB.IntraState.MemRet19+4(r6)
	stw		r18, CB.IntraState.MemRet18+4(r6)
	lmw		r14, KDP.r14(r1)
	blr

########################################################################

	_alignToCacheBlock
KCallReturnFromExceptionFastPath
	lwz		r11, KDP.NKInfo.NanoKernelCallCounts(r1)
	mr		r10, r12
	addi	r11, r11, 1
	stw		r11, KDP.NKInfo.NanoKernelCallCounts(r1)
	mfsrr1	r11
	rlwimi	r7, r7, 32+bitMsrSE-bitContextFlagTraceWhenDone, ContextFlagTraceWhenDone

KCallReturnFromException
	cmplwi	cr1, r3, 1							; exception handler return value
	blt		cr1, @dispose
	mtcrf	crMaskFlags, r7
	beq		cr1, @propagate

; If handler returns an exception cause code 2-255, "force" this exception to the System Context.
	subi	r8, r3, 32
	lwz		r9, KDP.NKInfo.ExceptionForcedCount(r1)
	cmplwi	r8, 256-32
	addi	r9, r9, 1
	stw		r9, KDP.NKInfo.ExceptionForcedCount(r1)
	insrwi	r7, r3, 8, 0
	blt		RunSystemContext
	li		r8, ecTrapInstr
	b		Exception							; (error if number is > max exception number)

; If handler returns 0 (System Context must always do this), return to userspace.
@dispose
	lwz		r8, CB.IntraState.Flags(r6)			; Restore Context flags (inc exception number?)
	lwz		r10, CB.FaultSrcPC+4(r6)
	rlwimi	r7, r8, 0, maskExceptionNum | maskContextFlags ; preserve global flags
	lwz		r8, CB.IntraState.Enables(r6)
	rlwimi	r11, r7, 0, maskMsrFlags
	stw		r8, KDP.Enables(r1)
	andi.	r8, r11, MsrFE0 + MsrFE1			; check: are floating-pt exceptions enabled?

	lwz		r12, CB.FaultSrcLR+4(r6)			; restore LR/r3/r4
	lwz		r3, CB.FaultSrcR3+4(r6)
	lwz		r4, CB.FaultSrcR4+4(r6)

	bnel	EnableFPU

	addi	r9, r6, CB.IntraState				; If MemRetry was interrupted, resume it.

	b		ReturnFromInt

; If handler returns 1, "propagate" this exception to the System Context
; (When we get back to the Alternate Context, it will be as if the exception was disposed.)
@propagate
	lwz		r9, KDP.NKInfo.ExceptionPropagateCount(r1)
	lwz		r8, CB.IntraState.Flags(r6)
	addi	r9, r9, 1
	stw		r9, KDP.NKInfo.ExceptionPropagateCount(r1)
	lwz		r10, CB.FaultSrcPC+4(r6)
	rlwimi	r7, r8, 0, maskExceptionNum | maskContextFlags ; preserve global flags
	lwz		r8, CB.IntraState.Enables(r6)
	mtcrf	crMaskContextFlags, r7
	rlwimi	r11, r7, 0, maskMsrFlags
	stw		r8, KDP.Enables(r1)

	lwz		r12, CB.FaultSrcLR+4(r6)			; restore LR/r3/r4
	lwz		r3, CB.FaultSrcR3+4(r6)
	lwz		r4, CB.FaultSrcR4+4(r6)

	bc		BO_IF_NOT, bitContextFlagMemRetryErr, RunSystemContext
	stmw	r14, KDP.r14(r1)					; When we *do* get back to this context,
	lwz		r17, CB.IntraState.MemRet17+4(r6)	; make sure MemRetry state can be resumed
	lwz		r20, CB.IntraState.MemRetData(r6)	; from InterState
	lwz		r21, CB.IntraState.MemRetData+4(r6)
	lwz		r19, CB.IntraState.MemRet19+4(r6)
	lwz		r18, CB.IntraState.MemRet18+4(r6)
	b		RunSystemContext

########################################################################

;	BEFORE
;		PowerPC exception vector saved r1/LR in SPRG1/2 and
;		jumped where directed by the VecTbl pointed to by
;		SPRG3. That function bl'ed here.
;
;	AFTER
;		Reg		Contains			Original saved in
;		---------------------------------------------
;		 r0		(itself)
;		 r1		KDP					SPRG1
;		 r2		(itself)					
;		 r3		(itself)
;		 r4		(itself)
;		 r5		(itself)
;		 r6		ContextBlock		EWA
;		 r7		Flags				ContextBlock
;		 r8		KDP					ContextBlock
;		 r9		(scratch CB ptr)	ContextBlock
;		r10		SRR0				ContextBlock
;		r11		SRR1				ContextBlock
;		r12		LR					ContextBlock
;		r13		CR					ContextBlock

LoadInterruptRegisters
	mfsprg	r1, 0
	stw		r6, KDP.r6(r1)
	mfsprg	r6, 1
	stw		r6, KDP.r1(r1)
	lwz		r6, KDP.ContextPtr(r1)
	stw		r7, CB.r7+4(r6)
	stw		r8, CB.r8+4(r6)
	stw		r9, CB.r9+4(r6)
	stw		r10, CB.r10+4(r6)
	stw		r11, CB.r11+4(r6)
	stw		r12, CB.r12+4(r6)
	stw		r13, CB.r13+4(r6)
	mfsrr0	r10
	mfcr	r13
	lwz		r7, KDP.Flags(r1)
	mfsprg	r12, 2
	mfsrr1	r11
	blr

########################################################################

Exception
	lwz		r9, KDP.Enables(r1)
	mtcrf	crMaskFlags, r7

	rlwnm.	r9, r9, r8, 0, 0				; BLT taken if exception enabled

	insrwi	r7, r8, 8, 0					; Exception code to hi byte of Flags

	slwi	r8, r8, 2						; Increment counter, easy enough
	add		r8, r8, r1
	lwz		r9, KDP.NKInfo.ExceptionCauseCounts(r8)
	addi	r9, r9, 1
	stw		r9, KDP.NKInfo.ExceptionCauseCounts(r8)

	blt		ExceptionCommon				; exception enabled => run userspace handler
	;fall through							; Alt Context has left exception disabled => Sys Context

########################################################################

RunSystemContext
	lwz		r9, KDP.ECBPtr(r1)				; System ("Emulator") ContextBlock

	addi	r8, r1, KDP.VecTblSystem		; System VecTbl
	mtsprg	3, r8

	bcl		BO_IF, bitGlobalFlagSystem, SystemCrash	; System Context already running!

	;	Fallthru (new CB in r9, old CB in r6)

########################################################################

SwitchContext ; OldCB *r6, NewCB *r9
;	Run the System or Alternate Context
	lwz		r8, KDP.Enables(r1)
	stw		r7, CB.InterState.Flags(r6)
	stw		r8, CB.InterState.Enables(r6)

	bc		BO_IF_NOT, bitContextFlagMemRetryErr, @can_dispose_mr_state
	stw		r17, CB.InterState.MemRet17+4(r6)
	stw		r20, CB.InterState.MemRetData(r6)
	stw		r21, CB.InterState.MemRetData+4(r6)
	stw		r19, CB.InterState.MemRet19+4(r6)
	stw		r18, CB.InterState.MemRet18+4(r6)
	lmw		r14, KDP.r14(r1)
@can_dispose_mr_state

	mfxer	r8
	stw		r13, CB.CR+4(r6)
	stw		r8, CB.XER+4(r6)
	stw		r12, CB.LR+4(r6)
	mfctr	r8
	stw		r10, CB.PC+4(r6)
	stw		r8, CB.CTR+4(r6)

	bc		BO_IF_NOT, bitGlobalFlagMQReg, @no_mq
	lwz		r8, CB.MQ+4(r9)
	mfspr	r12, mq
	mtspr	mq, r8
	stw		r12, CB.MQ+4(r6)
@no_mq

	lwz		r8, KDP.r1(r1)
	stw		r0, CB.r0+4(r6)
	stw		r8, CB.r1+4(r6)
	stw		r2, CB.r2+4(r6)
	stw		r3, CB.r3+4(r6)
	stw		r4, CB.r4+4(r6)
	lwz		r8, KDP.r6(r1)
	stw		r5, CB.r5+4(r6)
	stw		r8, CB.r6+4(r6)
	_band.	r8, r11, bitMsrFP
	stw		r14, CB.r14+4(r6)
	stw		r15, CB.r15+4(r6)
	stw		r16, CB.r16+4(r6)
	stw		r17, CB.r17+4(r6)
	stw		r18, CB.r18+4(r6)
	stw		r19, CB.r19+4(r6)
	stw		r20, CB.r20+4(r6)
	stw		r21, CB.r21+4(r6)
	stw		r22, CB.r22+4(r6)
	stw		r23, CB.r23+4(r6)
	stw		r24, CB.r24+4(r6)
	stw		r25, CB.r25+4(r6)
	stw		r26, CB.r26+4(r6)
	stw		r27, CB.r27+4(r6)
	stw		r28, CB.r28+4(r6)
	stw		r29, CB.r29+4(r6)
	stw		r30, CB.r30+4(r6)
	stw		r31, CB.r31+4(r6)
	bnel	DisableFPU

	lwz		r8, KDP.OtherContextDEC(r1)
	mfdec	r31
	cmpwi	r8, 0
	stw		r31, KDP.OtherContextDEC(r1)
	mtdec	r8
	blel	ResetDEC ; to r8

	lwz		r8, CB.InterState.Flags(r9)				; r8 is the new Flags variable
	stw		r9, KDP.ContextPtr(r1)
	xoris	r7, r7, GlobalFlagSystem >> 16			; flip Emulator flag
	rlwimi	r11, r8, 0, maskMsrFlags
	mr		r6, r9									; change the magic ContextBlock register
	rlwimi	r7, r8, 0, maskContextFlags				; change bottom half of flags only

	andi.	r8, r11, MsrFE0 + MsrFE1				; FP exceptions enabled in new context?

	lwz		r8, CB.InterState.Enables(r6)
	lwz		r13, CB.CR+4(r6)
	stw		r8, KDP.Enables(r1)
	lwz		r8, CB.XER+4(r6)
	lwz		r12, CB.LR+4(r6)
	mtxer	r8
	lwz		r8, CB.CTR+4(r6)
	lwz		r10, CB.PC+4(r6)
	mtctr	r8

	bnel	ReloadFPU									; FP exceptions enabled, so load FPU

	stwcx.	r0, 0, r1

	lwz		r8, CB.r1+4(r6)
	lwz		r0, CB.r0+4(r6)
	stw		r8, KDP.r1(r1)
	lwz		r2, CB.r2+4(r6)
	lwz		r3, CB.r3+4(r6)
	lwz		r4, CB.r4+4(r6)
	lwz		r8, CB.r6+4(r6)
	lwz		r5, CB.r5+4(r6)
	stw		r8, KDP.r6(r1)
	lwz		r14, CB.r14+4(r6)
	lwz		r15, CB.r15+4(r6)
	lwz		r16, CB.r16+4(r6)
	lwz		r17, CB.r17+4(r6)
	lwz		r18, CB.r18+4(r6)
	lwz		r19, CB.r19+4(r6)
	lwz		r20, CB.r20+4(r6)
	lwz		r21, CB.r21+4(r6)
	lwz		r22, CB.r22+4(r6)
	lwz		r23, CB.r23+4(r6)
	lwz		r24, CB.r24+4(r6)
	lwz		r25, CB.r25+4(r6)
	lwz		r26, CB.r26+4(r6)
	lwz		r27, CB.r27+4(r6)
	lwz		r28, CB.r28+4(r6)
	lwz		r29, CB.r29+4(r6)
	lwz		r30, CB.r30+4(r6)
	lwz		r31, CB.r31+4(r6)

########################################################################

ReturnFromInt ; If ContextFlagMemRetryErr && ContextFlagResumeMemRetry, please pass KernelState ptr in r9
	andi.	r8, r7, ContextFlagTraceWhenDone | ContextFlagMemRetryErr
	bnel	@special_cases			; Keep rare cases out of the hot path

	stw		r7, KDP.Flags(r1)		; Save kernel flags for next interrupt
	mtlr	r12						; Restore user SPRs from kernel GPRs
	mtsrr0	r10
	mtsrr1	r11
	mtcr	r13
	lwz		r10, CB.r10+4(r6)		; Restore user GPRs from ContextBlock
	lwz		r11, CB.r11+4(r6)
	lwz		r12, CB.r12+4(r6)
	lwz		r13, CB.r13+4(r6)
	lwz		r7, CB.r7+4(r6)
	lwz		r8, CB.r8+4(r6)
	lwz		r9, CB.r9+4(r6)
	lwz		r6, KDP.r6(r1)			; Restore last two registers from EWA
	lwz		r1, KDP.r1(r1)
	rfi								; Go

@special_cases
	mtcrf	crMaskFlags, r7
	bc		BO_IF_NOT, bitContextFlagMemRetryErr, @no_memretry			; If MemRetry had to be paused for an exception
	_clear	r7, r7, bitContextFlagMemRetryErr							; which is now finished, finish MemRetry.
	bc		BO_IF, bitContextFlagResumeMemRetry, @resume_memretry
	_clear	r7, r7, bitContextFlagTraceWhenDone
	b		@justreturn

@no_memretry
	bc		BO_IF_NOT, bitContextFlagTraceWhenDone, @justreturn			; If this current interrupt was raised when
	_clear	r7, r7, bitContextFlagTraceWhenDone							; every instruction should be followed by a
	stw		r7, KDP.Flags(r1)											; Trace exception, then raise one.
	li		r8, ecInstTrace
	b		Exception

@justreturn
	blr

@resume_memretry ; Pick up where an MRException left off, now that the Exception has been disposed.
	stw		r7, KDP.Flags(r1)

	stw		r0, KDP.r0(r1)
	stw		r2, KDP.r2(r1)
	stw		r3, KDP.r3(r1)
	stw		r4, KDP.r4(r1)
	stw		r5, KDP.r5(r1)

	lwz		r8, CB.r7+4(r6)
	stw		r8, KDP.r7(r1)
	lwz		r8, CB.r8+4(r6)
	stw		r8, KDP.r8(r1)
	lwz		r8, CB.r9+4(r6)
	stw		r8, KDP.r9(r1)
	lwz		r8, CB.r10+4(r6)
	stw		r8, KDP.r10(r1)
	lwz		r8, CB.r11+4(r6)
	stw		r8, KDP.r11(r1)
	lwz		r8, CB.r12+4(r6)
	stw		r8, KDP.r12(r1)
	lwz		r8, CB.r13+4(r6)
	stw		r8, KDP.r13(r1)

	stmw	r14, KDP.r14(r1)

	lwz		r17, KernelState.MemRet17+4(r9)		; Get the MR state from IntraState (if context was never switched)
	lwz		r20, KernelState.MemRetData(r9)		; or InterState (if exception was propagated to System Context and
	lwz		r21, KernelState.MemRetData+4(r9)	; we are now switching back to Alternate Context).
	lwz		r19, KernelState.MemRet19+4(r9)
	lwz		r18, KernelState.MemRet18+4(r9)
	_clear	r16, r7, bitContextFlagMemRetryErr

	lwz		r25, KDP.MRBase(r1)			; MRRestab is indexed by the first arg of MROptab?
	extrwi.	r22, r17, 4, 27				; 
	add		r19, r19, r22				; Correct r19 (EA) by adding len from r17
	rlwimi	r25, r17, 7, 25, 30
	lhz		r26, MRRestab-MRBase(r25)

	insrwi	r25, r19, 3, 28				; Set Memtab alignment modulus
	stw		r16, KDP.Flags(r1)
	rlwimi	r26, r26, 8, 8, 15			; First byte of MRRestab is for cr3/cr4
	insrwi	r25, r17, 4, 24				; len and load/store from second arg of MROptab?
	mtcrf	0x10, r26					; Set CR3
	lha		r22, MRMemtab-MRBase(r25)	; Jump to MRMemtab...

	addi	r23, r1, KDP.VecTblMemRetry
	add		r22, r22, r25
	mfsprg	r24, 3
	mtlr	r22
	mtsprg	3, r23
	mfmsr	r14
	_set	r15, r14, bitMsrDR
	mtmsr	r15
	rlwimi	r25, r26, 2, 22, 29			; Second byte of MRRestab is a secondary routine
	bnelr
	b		MRDoSecondary

########################################################################

ResetDEC ; to r8
	lis		r31, 0x7FFF
	mtdec	r31
	mtdec	r8
	blr