pfpsp.s

linux内核源码

# was exact, then a branch to _real_inex() is made.
	btst		&ovfl_bit,FPSR_EXCEPT(%a6) # was overflow set?
	beq.w		fu_out_done		# no

fu_out_ovflchk:
	btst		&inex2_bit,FPCR_ENABLE(%a6) # was inexact enabled?
	beq.w		fu_out_done		# no
	bra.w		fu_inex			# yes

#
# The fp move out that took the "Unimplemented Data Type" exception was
# being traced. Since the stack frames are similar, get the "current" PC
# from FPIAR and put it in the trace stack frame then jump to _real_trace().
#
#		  UNSUPP FRAME		   TRACE FRAME
#		*****************	*****************
#		*      EA	*	*    Current	*
#		*		*	*      PC	*
#		*****************	*****************
#		* 0x3 *  0x0dc	*	* 0x2 *  0x024	*
#		*****************	*****************
#		*     Next	*	*     Next	*
#		*      PC	*	*      PC	*
#		*****************	*****************
#		*      SR	*	*      SR	*
#		*****************	*****************
#
fu_out_trace:
	mov.w		&0x2024,0x6(%sp)
	fmov.l		%fpiar,0x8(%sp)
	bra.l		_real_trace

# an exception occurred and that exception was enabled.
fu_out_exc:
	subi.l		&24,%d0			# fix offset to be 0-8

# we don't mess with the existing fsave frame. just re-insert it and
# jump to the "_real_{}()" handler...
	mov.w		(tbl_fu_out.b,%pc,%d0.w*2),%d0
	jmp		(tbl_fu_out.b,%pc,%d0.w*1)

	swbeg		&0x8
tbl_fu_out:
	short		tbl_fu_out	- tbl_fu_out	# BSUN can't happen
	short		tbl_fu_out	- tbl_fu_out	# SNAN can't happen
	short		fu_operr	- tbl_fu_out	# OPERR
	short		fu_ovfl		- tbl_fu_out	# OVFL
	short		fu_unfl		- tbl_fu_out	# UNFL
	short		tbl_fu_out	- tbl_fu_out	# DZ can't happen
	short		fu_inex		- tbl_fu_out	# INEX2
	short		tbl_fu_out	- tbl_fu_out	# INEX1 won't make it here

# for snan,operr,ovfl,unfl, src op is still in FP_SRC so just
# frestore it.
fu_snan:
	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

	mov.w		&0x30d8,EXC_VOFF(%a6)	# vector offset = 0xd8
	mov.w		&0xe006,2+FP_SRC(%a6)

	frestore	FP_SRC(%a6)

	unlk		%a6


	bra.l		_real_snan

fu_operr:
	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

	mov.w		&0x30d0,EXC_VOFF(%a6)	# vector offset = 0xd0
	mov.w		&0xe004,2+FP_SRC(%a6)

	frestore	FP_SRC(%a6)

	unlk		%a6


	bra.l		_real_operr

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

	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

	mov.w		&0x30d4,EXC_VOFF(%a6)	# vector offset = 0xd4
	mov.w		&0xe005,2+FP_SRC(%a6)

	frestore	FP_SRC(%a6)		# restore EXOP

	unlk		%a6

	bra.l		_real_ovfl

# underflow can happen for extended precision. extended precision opclass
# three instruction exceptions don't update the stack pointer. so, if the
# exception occurred from user mode, then simply update a7 and exit normally.
# if the exception occurred from supervisor mode, check if
fu_unfl:
	mov.l		EXC_A6(%a6),(%a6)	# restore a6

	btst		&0x5,EXC_SR(%a6)
	bne.w		fu_unfl_s

	mov.l		EXC_A7(%a6),%a0		# restore a7 whether we need
	mov.l		%a0,%usp		# to or not...

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

	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

	mov.w		&0x30cc,EXC_VOFF(%a6)	# vector offset = 0xcc
	mov.w		&0xe003,2+FP_SRC(%a6)

	frestore	FP_SRC(%a6)		# restore EXOP

	unlk		%a6

	bra.l		_real_unfl

fu_unfl_s:
	cmpi.b		SPCOND_FLG(%a6),&mda7_flg # was the <ea> mode -(sp)?
	bne.b		fu_unfl_cont

# the extended precision result is still in fp0. but, we need to save it
# somewhere on the stack until we can copy it to its final resting place
# (where the exc frame is currently). make sure it's not at the top of the
# frame or it will get overwritten when the exc stack frame is shifted "down".
	fmovm.x		&0x80,FP_SRC(%a6)	# put answer on stack
	fmovm.x		&0x40,FP_DST(%a6)	# put EXOP on stack

	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

	mov.w		&0x30cc,EXC_VOFF(%a6)	# vector offset = 0xcc
	mov.w		&0xe003,2+FP_DST(%a6)

	frestore	FP_DST(%a6)		# restore EXOP

	mov.l		(%a6),%a6		# restore frame pointer

	mov.l		LOCAL_SIZE+EXC_SR(%sp),LOCAL_SIZE+EXC_SR-0xc(%sp)
	mov.l		LOCAL_SIZE+2+EXC_PC(%sp),LOCAL_SIZE+2+EXC_PC-0xc(%sp)
	mov.l		LOCAL_SIZE+EXC_EA(%sp),LOCAL_SIZE+EXC_EA-0xc(%sp)

# now, copy the result to the proper place on the stack
	mov.l		LOCAL_SIZE+FP_SRC_EX(%sp),LOCAL_SIZE+EXC_SR+0x0(%sp)
	mov.l		LOCAL_SIZE+FP_SRC_HI(%sp),LOCAL_SIZE+EXC_SR+0x4(%sp)
	mov.l		LOCAL_SIZE+FP_SRC_LO(%sp),LOCAL_SIZE+EXC_SR+0x8(%sp)

	add.l		&LOCAL_SIZE-0x8,%sp

	bra.l		_real_unfl

# fmove in and out enter here.
fu_inex:
	fmovm.x		&0x40,FP_SRC(%a6)	# save EXOP to the stack

	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

	mov.w		&0x30c4,EXC_VOFF(%a6)	# vector offset = 0xc4
	mov.w		&0xe001,2+FP_SRC(%a6)

	frestore	FP_SRC(%a6)		# restore EXOP

	unlk		%a6


	bra.l		_real_inex

#########################################################################
#########################################################################
fu_in_pack:


# I'm not sure at this point what FPSR bits are valid for this instruction.
# so, since the emulation routines re-create them anyways, zero exception field
	andi.l		&0x0ff00ff,USER_FPSR(%a6) # zero exception field

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

	bsr.l		get_packed		# fetch packed src operand

	lea		FP_SRC(%a6),%a0		# pass ptr to src
	bsr.l		set_tag_x		# set src optype tag

	mov.b		%d0,STAG(%a6)		# save src optype tag

	bfextu		EXC_CMDREG(%a6){&6:&3},%d0 # dyadic; load dst reg

# bit five of the fp extension word separates the monadic and dyadic operations
# at this point
	btst		&0x5,1+EXC_CMDREG(%a6)	# is operation monadic or dyadic?
	beq.b		fu_extract_p		# monadic
	cmpi.b		1+EXC_CMDREG(%a6),&0x3a	# is operation an ftst?
	beq.b		fu_extract_p		# yes, so it's monadic, too

	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		fu_op2_done_p		# no
	bsr.l		unnorm_fix		# yes; convert to NORM,DENORM,or ZERO
fu_op2_done_p:
	mov.b		%d0,DTAG(%a6)		# save dst optype tag

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

	bfextu		1+EXC_CMDREG(%a6){&1:&7},%d1 # extract extension

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

	mov.l		(tbl_unsupp.l,%pc,%d1.l*4),%d1 # fetch routine addr
	jsr		(tbl_unsupp.l,%pc,%d1.l*1)

#
# Exceptions in order of precedence:
#	BSUN	: none
#	SNAN	: all dyadic ops
#	OPERR	: fsqrt(-NORM)
#	OVFL	: all except ftst,fcmp
#	UNFL	: all except ftst,fcmp
#	DZ	: fdiv
#	INEX2	: all except ftst,fcmp
#	INEX1	: all
#

# we determine the highest priority exception(if any) set by the
# emulation routine that has also been enabled by the user.
	mov.b		FPCR_ENABLE(%a6),%d0	# fetch exceptions enabled
	bne.w		fu_in_ena_p		# some are enabled

fu_in_cont_p:
# fcmp and ftst do not store any result.
	mov.b		1+EXC_CMDREG(%a6),%d0	# fetch extension
	andi.b		&0x38,%d0		# extract bits 3-5
	cmpi.b		%d0,&0x38		# is instr fcmp or ftst?
	beq.b		fu_in_exit_p		# yes

	bfextu		EXC_CMDREG(%a6){&6:&3},%d0 # dyadic; load dst reg
	bsr.l		store_fpreg		# store the result

fu_in_exit_p:

	btst		&0x5,EXC_SR(%a6)	# user or supervisor?
	bne.w		fu_in_exit_s_p		# supervisor

	mov.l		EXC_A7(%a6),%a0		# update user a7
	mov.l		%a0,%usp

fu_in_exit_cont_p:
	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			# unravel stack frame

	btst		&0x7,(%sp)		# is trace on?
	bne.w		fu_trace_p		# yes

	bra.l		_fpsp_done		# exit to os

# the exception occurred in supervisor mode. check to see if the
# addressing mode was (a7)+. if so, we'll need to shift the
# stack frame "up".
fu_in_exit_s_p:
	btst		&mia7_bit,SPCOND_FLG(%a6) # was ea mode (a7)+
	beq.b		fu_in_exit_cont_p	# no

	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			# unravel stack frame

# shift the stack frame "up". we don't really care about the <ea> field.
	mov.l		0x4(%sp),0x10(%sp)
	mov.l		0x0(%sp),0xc(%sp)
	add.l		&0xc,%sp

	btst		&0x7,(%sp)		# is trace on?
	bne.w		fu_trace_p		# yes

	bra.l		_fpsp_done		# exit to os

fu_in_ena_p:
	and.b		FPSR_EXCEPT(%a6),%d0	# keep only ones enabled & set
	bfffo		%d0{&24:&8},%d0		# find highest priority exception
	bne.b		fu_in_exc_p		# at least one was set

#
# No exceptions occurred that were also enabled. Now:
#
#	if (OVFL && ovfl_disabled && inexact_enabled) {
#	    branch to _real_inex() (even if the result was exact!);
#	} else {
#	    save the result in the proper fp reg (unless the op is fcmp or ftst);
#	    return;
#	}
#
	btst		&ovfl_bit,FPSR_EXCEPT(%a6) # was overflow set?
	beq.w		fu_in_cont_p		# no

fu_in_ovflchk_p:
	btst		&inex2_bit,FPCR_ENABLE(%a6) # was inexact enabled?
	beq.w		fu_in_cont_p		# no
	bra.w		fu_in_exc_ovfl_p	# do _real_inex() now

#
# An exception occurred and that exception was enabled:
#
#	shift enabled exception field into lo byte of d0;
#	if (((INEX2 || INEX1) && inex_enabled && OVFL && ovfl_disabled) ||
#	    ((INEX2 || INEX1) && inex_enabled && UNFL && unfl_disabled)) {
#		/*
#		 * this is the case where we must call _real_inex() now or else
#		 * there will be no other way to pass it the exceptional operand
#		 */
#		call _real_inex();
#	} else {
#		restore exc state (SNAN||OPERR||OVFL||UNFL||DZ||INEX) into the FPU;
#	}
#
fu_in_exc_p:
	subi.l		&24,%d0			# fix offset to be 0-8
	cmpi.b		%d0,&0x6		# is exception INEX? (6 or 7)
	blt.b		fu_in_exc_exit_p	# no

# the enabled exception was inexact
	btst		&unfl_bit,FPSR_EXCEPT(%a6) # did disabled underflow occur?
	bne.w		fu_in_exc_unfl_p	# yes
	btst		&ovfl_bit,FPSR_EXCEPT(%a6) # did disabled overflow occur?
	bne.w		fu_in_exc_ovfl_p	# yes

# here, we insert the correct fsave status value into the fsave frame for the
# corresponding exception. the operand in the fsave frame should be the original
# src operand.
# as a reminder for future predicted pain and agony, we are passing in fsave the
# "non-skewed" operand for cases of sgl and dbl src INFs,NANs, and DENORMs.
# this is INCORRECT for enabled SNAN which would give to the user the skewed SNAN!!!
fu_in_exc_exit_p:
	btst		&0x5,EXC_SR(%a6)	# user or supervisor?
	bne.w		fu_in_exc_exit_s_p	# supervisor

	mov.l		EXC_A7(%a6),%a0		# update user a7
	mov.l		%a0,%usp

fu_in_exc_exit_cont_p:
	mov.w		(tbl_except_p.b,%pc,%d0.w*2),2+FP_SRC(%a6)

	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)		# restore src op

	unlk		%a6

	btst		&0x7,(%sp)		# is trace enabled?
	bne.w		fu_trace_p		# yes

	bra.l		_fpsp_done

tbl_except_p:
	short		0xe000,0xe006,0xe004,0xe005
	short		0xe003,0xe002,0xe001,0xe001

fu_in_exc_ovfl_p:
	mov.w		&0x3,%d0
	bra.w		fu_in_exc_exit_p

fu_in_exc_unfl_p:
	mov.w		&0x4,%d0
	bra.w		fu_in_exc_exit_p

fu_in_exc_exit_s_p:
	btst		&mia7_bit,SPCOND_FLG(%a6)
	beq.b		fu_in_exc_exit_cont_p

	mov.w		(tbl_except_p.b,%pc,%d0.w*2),2+FP_SRC(%a6)

	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)