pfpsp.s

linux内核源码

	beq.l		_fpsp_done		# no

	fmov.l		%fpiar,0x8(%sp)		# "Current PC" is in FPIAR
	mov.w		&0x2024,0x6(%sp)	# stk fmt = 0x2; voff = 0x024
	bra.l		_real_trace

#########################################################################
# XDEF ****************************************************************	#
#	_fpsp_unfl(): 060FPSP entry point for FP Underflow exception.	#
#									#
#	This handler should be the first code executed upon taking the	#
#	FP Underflow exception in an operating system.			#
#									#
# XREF ****************************************************************	#
#	_imem_read_long() - read instruction longword			#
#	fix_skewed_ops() - adjust src operand in fsave frame		#
#	set_tag_x() - determine optype of src/dst operands		#
#	store_fpreg() - store opclass 0 or 2 result to FP regfile	#
#	unnorm_fix() - change UNNORM operands to NORM or ZERO		#
#	load_fpn2() - load dst operand from FP regfile			#
#	fout() - emulate an opclass 3 instruction			#
#	tbl_unsupp - add of table of emulation routines for opclass 0,2	#
#	_fpsp_done() - "callout" for 060FPSP exit (all work done!)	#
#	_real_ovfl() - "callout" for Overflow exception enabled code	#
#	_real_inex() - "callout" for Inexact exception enabled code	#
#	_real_trace() - "callout" for Trace exception code		#
#									#
# INPUT ***************************************************************	#
#	- The system stack contains the FP Unfl exception stack frame	#
#	- The fsave frame contains the source operand			#
#									#
# OUTPUT **************************************************************	#
#	Underflow Exception enabled:					#
#	- The system stack is unchanged					#
#	- The fsave frame contains the adjusted src op for opclass 0,2	#
#	Underflow Exception disabled:					#
#	- The system stack is unchanged					#
#	- The "exception present" flag in the fsave frame is cleared	#
#									#
# ALGORITHM ***********************************************************	#
#	On the 060, if an FP underflow is present as the result of any	#
# instruction, the 060 will take an underflow exception whether the	#
# exception is enabled or disabled in the FPCR. For the disabled case,	#
# This handler emulates the instruction to determine what the correct	#
# default result should be for the operation. This default result is	#
# then stored in either the FP regfile, data regfile, or memory.	#
# Finally, the handler exits through the "callout" _fpsp_done()		#
# denoting that no exceptional conditions exist within the machine.	#
#	If the exception is enabled, then this handler must create the	#
# exceptional operand and plave it in the fsave state frame, and store	#
# the default result (only if the instruction is opclass 3). For	#
# exceptions enabled, this handler must exit through the "callout"	#
# _real_unfl() so that the operating system enabled overflow handler	#
# can handle this case.							#
#	Two other conditions exist. First, if underflow was disabled	#
# but the inexact exception was enabled and the result was inexact,	#
# this handler must exit through the "callout" _real_inex().		#
# was inexact.								#
#	Also, in the case of an opclass three instruction where		#
# underflow was disabled and the trace exception was enabled, this	#
# handler must exit through the "callout" _real_trace().		#
#									#
#########################################################################

	global		_fpsp_unfl
_fpsp_unfl:

#$#	sub.l		&24,%sp			# make room for src/dst

	link.w		%a6,&-LOCAL_SIZE	# init stack frame

	fsave		FP_SRC(%a6)		# grab the "busy" frame

	movm.l		&0x0303,EXC_DREGS(%a6)	# save d0-d1/a0-a1
	fmovm.l		%fpcr,%fpsr,%fpiar,USER_FPCR(%a6) # save ctrl regs
	fmovm.x		&0xc0,EXC_FPREGS(%a6)	# save fp0-fp1 on stack

# the FPIAR holds the "current PC" of the faulting instruction
	mov.l		USER_FPIAR(%a6),EXC_EXTWPTR(%a6)
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x4,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_long		# fetch the instruction words
	mov.l		%d0,EXC_OPWORD(%a6)

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

	btst		&0x5,EXC_CMDREG(%a6)	# is instr an fmove out?
	bne.w		funfl_out


	lea		FP_SRC(%a6),%a0		# pass: ptr to src op
	bsr.l		fix_skewed_ops		# fix src op

	lea		FP_SRC(%a6),%a0		# pass: ptr to src op
	bsr.l		set_tag_x		# tag the operand type
	mov.b		%d0,STAG(%a6)		# maybe NORM,DENORM

# bit five of the fp ext word separates the monadic and dyadic operations
# that can pass through fpsp_unfl(). remember that fcmp, and ftst
# will never take this exception.
	btst		&0x5,1+EXC_CMDREG(%a6)	# is op monadic or dyadic?
	beq.b		funfl_extract		# monadic

# now, what's left that's not dyadic is fsincos. we can distinguish it
# from all dyadics by the '0110xxx pattern
	btst		&0x4,1+EXC_CMDREG(%a6)	# is op an fsincos?
	bne.b		funfl_extract		# yes

	bfextu		EXC_CMDREG(%a6){&6:&3},%d0 # dyadic; load dst reg
	bsr.l		load_fpn2		# load dst into FP_DST

	lea		FP_DST(%a6),%a0		# pass: ptr to dst op
	bsr.l		set_tag_x		# tag the operand type
	cmpi.b		%d0,&UNNORM		# is operand an UNNORM?
	bne.b		funfl_op2_done		# no
	bsr.l		unnorm_fix		# yes; convert to NORM,DENORM,or ZERO
funfl_op2_done:
	mov.b		%d0,DTAG(%a6)		# save dst optype tag

funfl_extract:

#$#	mov.l		FP_SRC_EX(%a6),TRAP_SRCOP_EX(%a6)
#$#	mov.l		FP_SRC_HI(%a6),TRAP_SRCOP_HI(%a6)
#$#	mov.l		FP_SRC_LO(%a6),TRAP_SRCOP_LO(%a6)
#$#	mov.l		FP_DST_EX(%a6),TRAP_DSTOP_EX(%a6)
#$#	mov.l		FP_DST_HI(%a6),TRAP_DSTOP_HI(%a6)
#$#	mov.l		FP_DST_LO(%a6),TRAP_DSTOP_LO(%a6)

	clr.l		%d0
	mov.b		FPCR_MODE(%a6),%d0	# pass rnd prec/mode

	mov.b		1+EXC_CMDREG(%a6),%d1
	andi.w		&0x007f,%d1		# extract extension

	andi.l		&0x00ff01ff,USER_FPSR(%a6)

	fmov.l		&0x0,%fpcr		# zero current control regs
	fmov.l		&0x0,%fpsr

	lea		FP_SRC(%a6),%a0
	lea		FP_DST(%a6),%a1

# maybe we can make these entry points ONLY the OVFL entry points of each routine.
	mov.l		(tbl_unsupp.l,%pc,%d1.w*4),%d1 # fetch routine addr
	jsr		(tbl_unsupp.l,%pc,%d1.l*1)

	bfextu		EXC_CMDREG(%a6){&6:&3},%d0
	bsr.l		store_fpreg

# The `060 FPU multiplier hardware is such that if the result of a
# multiply operation is the smallest possible normalized number
# (0x00000000_80000000_00000000), then the machine will take an
# underflow exception. Since this is incorrect, we need to check
# if our emulation, after re-doing the operation, decided that
# no underflow was called for. We do these checks only in
# funfl_{unfl,inex}_on() because w/ both exceptions disabled, this
# special case will simply exit gracefully with the correct result.

# the exceptional possibilities we have left ourselves with are ONLY overflow
# and inexact. and, the inexact is such that overflow occurred and was disabled
# but inexact was enabled.
	btst		&unfl_bit,FPCR_ENABLE(%a6)
	bne.b		funfl_unfl_on

funfl_chkinex:
	btst		&inex2_bit,FPCR_ENABLE(%a6)
	bne.b		funfl_inex_on

funfl_exit:
	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0-fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	unlk		%a6
#$#	add.l		&24,%sp
	bra.l		_fpsp_done

# overflow is enabled AND overflow, of course, occurred. so, we have the EXOP
# in fp1 (don't forget to save fp0). what to do now?
# well, we simply have to get to go to _real_unfl()!
funfl_unfl_on:

# The `060 FPU multiplier hardware is such that if the result of a
# multiply operation is the smallest possible normalized number
# (0x00000000_80000000_00000000), then the machine will take an
# underflow exception. Since this is incorrect, we check here to see
# if our emulation, after re-doing the operation, decided that
# no underflow was called for.
	btst		&unfl_bit,FPSR_EXCEPT(%a6)
	beq.w		funfl_chkinex

funfl_unfl_on2:
	fmovm.x		&0x40,FP_SRC(%a6)	# save EXOP (fp1) to stack

	mov.w		&0xe003,2+FP_SRC(%a6)	# save exc status

	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0-fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	frestore	FP_SRC(%a6)		# do this after fmovm,other f<op>s!

	unlk		%a6

	bra.l		_real_unfl

# undeflow occurred but is disabled. meanwhile, inexact is enabled. therefore,
# we must jump to real_inex().
funfl_inex_on:

# The `060 FPU multiplier hardware is such that if the result of a
# multiply operation is the smallest possible normalized number
# (0x00000000_80000000_00000000), then the machine will take an
# underflow exception.
# But, whether bogus or not, if inexact is enabled AND it occurred,
# then we have to branch to real_inex.

	btst		&inex2_bit,FPSR_EXCEPT(%a6)
	beq.w		funfl_exit

funfl_inex_on2:

	fmovm.x		&0x40,FP_SRC(%a6)	# save EXOP to stack

	mov.b		&0xc4,1+EXC_VOFF(%a6)	# vector offset = 0xc4
	mov.w		&0xe001,2+FP_SRC(%a6)	# save exc status

	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0-fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	frestore	FP_SRC(%a6)		# do this after fmovm,other f<op>s!

	unlk		%a6

	bra.l		_real_inex

#######################################################################
funfl_out:


#$#	mov.l		FP_SRC_EX(%a6),TRAP_SRCOP_EX(%a6)
#$#	mov.l		FP_SRC_HI(%a6),TRAP_SRCOP_HI(%a6)
#$#	mov.l		FP_SRC_LO(%a6),TRAP_SRCOP_LO(%a6)

# the src operand is definitely a NORM(!), so tag it as such
	mov.b		&NORM,STAG(%a6)		# set src optype tag

	clr.l		%d0
	mov.b		FPCR_MODE(%a6),%d0	# pass rnd prec/mode

	and.l		&0xffff00ff,USER_FPSR(%a6) # zero all but accured field

	fmov.l		&0x0,%fpcr		# zero current control regs
	fmov.l		&0x0,%fpsr

	lea		FP_SRC(%a6),%a0		# pass ptr to src operand

	bsr.l		fout

	btst		&unfl_bit,FPCR_ENABLE(%a6)
	bne.w		funfl_unfl_on2

	btst		&inex2_bit,FPCR_ENABLE(%a6)
	bne.w		funfl_inex_on2

	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0-fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	unlk		%a6
#$#	add.l		&24,%sp

	btst		&0x7,(%sp)		# is trace on?
	beq.l		_fpsp_done		# no

	fmov.l		%fpiar,0x8(%sp)		# "Current PC" is in FPIAR
	mov.w		&0x2024,0x6(%sp)	# stk fmt = 0x2; voff = 0x024
	bra.l		_real_trace

#########################################################################
# XDEF ****************************************************************	#
#	_fpsp_unsupp(): 060FPSP entry point for FP "Unimplemented	#
#		        Data Type" exception.				#
#									#
#	This handler should be the first code executed upon taking the	#
#	FP Unimplemented Data Type exception in an operating system.	#
#									#
# XREF ****************************************************************	#
#	_imem_read_{word,long}() - read instruction word/longword	#
#	fix_skewed_ops() - adjust src operand in fsave frame		#
#	set_tag_x() - determine optype of src/dst operands		#
#	store_fpreg() - store opclass 0 or 2 result to FP regfile	#
#	unnorm_fix() - change UNNORM operands to NORM or ZERO		#
#	load_fpn2() - load dst operand from FP regfile			#
#	load_fpn1() - load src operand from FP regfile			#
#	fout() - emulate an opclass 3 instruction			#
#	tbl_unsupp - add of table of emulation routines for opclass 0,2	#
#	_real_inex() - "callout" to operating system inexact handler	#
#	_fpsp_done() - "callout" for exit; work all done		#
#	_real_trace() - "callout" for Trace enabled exception		#
#	funimp_skew() - adjust fsave src ops to "incorrect" value	#
#	_real_snan() - "callout" for SNAN exception			#
#	_real_operr() - "callout" for OPERR exception			#
#	_real_ovfl() - "callout" for OVFL exception			#
#	_real_unfl() - "callout" for UNFL exception			#
#	get_packed() - fetch packed operand from memory			#
#									#
# INPUT ***************************************************************	#
#	- The system stack contains the "Unimp Data Type" stk frame	#
#	- The fsave frame contains the ssrc op (for UNNORM/DENORM)	#
#									#
# OUTPUT **************************************************************	#
#	If Inexact exception (opclass 3):				#
#	- The system stack is changed to an Inexact exception stk frame	#
#	If SNAN exception (opclass 3):					#
#	- The system stack is changed to an SNAN exception stk frame	#
#	If OPERR exception (opclass 3):					#
#	- The system stack is changed to an OPERR exception stk frame	#
#	If OVFL exception (opclass 3):					#
#	- The system stack is changed to an OVFL exception stk frame	#
#	If UNFL exception (opclass 3):					#
#	- The system stack is changed to an UNFL exception stack frame	#
#	If Trace exception enabled:					#
#	- The system stack is changed to a Trace exception stack frame	#
#	Else: (normal case)						#
#	- Correct result has been stored as appropriate			#
#									#
# ALGORITHM ***********************************************************	#
#	Two main instruction types can enter here: (1) DENORM or UNNORM	#
# unimplemented data types. These can be either opclass 0,2 or 3	#
# instructions, and (2) PACKED unimplemented data format instructions	#
# also of opclasses 0,2, or 3.						#
#	For UNNORM/DENORM opclass 0 and 2, the handler fetches the src	#
# operand from the fsave state frame and the dst operand (if dyadic)	#
# from the FP register file. The instruction is then emulated by	#
# choosing an emulation routine from a table of routines indexed by	#
# instruction type. Once the instruction has been emulated and result	#
# saved, then we check to see if any enabled exceptions resulted from	#
# instruction emulation. If none, then we exit through the "callout"	#
# _fpsp_done(). If there is an enabled FP exception, then we insert	#
# this exception into the FPU in the fsave state frame and then exit	#
# through _fpsp_done().							#
#	PACKED opclass 0 and 2 is similar in how the instruction is	#
# emulated and exceptions handled. The differences occur in how the	#
# handler loads the packed op (by calling get_packed() routine) and	#
# by the fact that a Trace exception could be pending for PACKED ops.	#
# If a Trace exception is pending, then the current exception stack	#
# frame is changed to a Trace exception stack frame and an exit is	#
# made through _real_trace().						#
#	For UNNORM/DENORM opclass 3, the actual move out to memory is	#
# performed by calling the routine fout(). If no exception should occur	#
# as the result of emulation, then an exit either occurs through	#
# _fpsp_done() or through _real_trace() if a Trace exception is pending	#
# (a Trace stack frame must be created here, too). If an FP exception	#
# should occur, then we must create an exception stack frame of that	#
# type and jump to either _real_snan(), _real_operr(), _real_inex(),	#
# _real_unfl(), or _real_ovfl() as appropriate. PACKED opclass 3	#
# emulation is performed in a similar manner.				#
#									#
#########################################################################

#
# (1) DENORM and UNNORM (unimplemented) data types:
#
#				post-instruction
#				*****************
#				*      EA	*
#	 pre-instruction	*		*
#	*****************	*****************
#	* 0x0 *  0x0dc  *	* 0x3 *  0x0dc  *
#	*****************	*****************
#	*     Next	*	*     Next	*
#	*      PC	*	*      PC	*
#	*****************	*****************
#	*      SR	*	*      SR	*
#	*****************	*****************
#
# (2) PACKED format (unsupported) opclasses two and three:
#	*****************
#	*      EA	*
#	*		*
#	*****************
#	* 0x2 *  0x0dc	*
#	*****************
#	*     Next	*
#	*      PC	*
#	*****************
#	*      SR	*
#	*****************
#
	global		_fpsp_unsupp
_fpsp_unsupp:

	link.w		%a6,&-LOCAL_SIZE	# init stack frame

	fsave		FP_SRC(%a6)		# save fp state

	movm.l		&0x0303,EXC_DREGS(%a6)	# save d0-d1/a0-a1
	fmovm.l		%fpcr,%fpsr,%fpiar,USER_FPCR(%a6) # save ctrl regs
	fmovm.x		&0xc0,EXC_FPREGS(%a6)	# save fp0-fp1 on stack

	btst		&0x5,EXC_SR(%a6)	# user or supervisor mode?
	bne.b		fu_s
fu_u: