xref: /openbmc/linux/arch/m68k/fpsp040/gen_except.S (revision e00d82d0) 
1|
2|	gen_except.sa 3.7 1/16/92
3|
4|	gen_except --- FPSP routine to detect reportable exceptions
5|
6|	This routine compares the exception enable byte of the
7|	user_fpcr on the stack with the exception status byte
8|	of the user_fpsr.
9|
10|	Any routine which may report an exceptions must load
11|	the stack frame in memory with the exceptional operand(s).
12|
13|	Priority for exceptions is:
14|
15|	Highest:	bsun
16|			snan
17|			operr
18|			ovfl
19|			unfl
20|			dz
21|			inex2
22|	Lowest:		inex1
23|
24|	Note: The IEEE standard specifies that inex2 is to be
25|	reported if ovfl occurs and the ovfl enable bit is not
26|	set but the inex2 enable bit is.
27|
28|
29|		Copyright (C) Motorola, Inc. 1990
30|			All Rights Reserved
31|
32|       For details on the license for this file, please see the
33|       file, README, in this same directory.
34
35GEN_EXCEPT:    |idnt    2,1 | Motorola 040 Floating Point Software Package
36
37	|section 8
38
39#include "fpsp.h"
40
41	|xref	real_trace
42	|xref	fpsp_done
43	|xref	fpsp_fmt_error
44
45exc_tbl:
46	.long	bsun_exc
47	.long	commonE1
48	.long	commonE1
49	.long	ovfl_unfl
50	.long	ovfl_unfl
51	.long	commonE1
52	.long	commonE3
53	.long	commonE3
54	.long	no_match
55
56	.global	gen_except
57gen_except:
58	cmpib	#IDLE_SIZE-4,1(%a7)	|test for idle frame
59	beq	do_check		|go handle idle frame
60	cmpib	#UNIMP_40_SIZE-4,1(%a7)	|test for orig unimp frame
61	beqs	unimp_x			|go handle unimp frame
62	cmpib	#UNIMP_41_SIZE-4,1(%a7)	|test for rev unimp frame
63	beqs	unimp_x			|go handle unimp frame
64	cmpib	#BUSY_SIZE-4,1(%a7)	|if size <> $60, fmt error
65	bnel	fpsp_fmt_error
66	leal	BUSY_SIZE+LOCAL_SIZE(%a7),%a1 |init a1 so fpsp.h
67|					;equates will work
68| Fix up the new busy frame with entries from the unimp frame
69|
70	movel	ETEMP_EX(%a6),ETEMP_EX(%a1) |copy etemp from unimp
71	movel	ETEMP_HI(%a6),ETEMP_HI(%a1) |frame to busy frame
72	movel	ETEMP_LO(%a6),ETEMP_LO(%a1)
73	movel	CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
74	movel	CMDREG1B(%a6),%d0		|fix cmd1b to make it
75	andl	#0x03c30000,%d0		|work for cmd3b
76	bfextu	CMDREG1B(%a6){#13:#1},%d1	|extract bit 2
77	lsll	#5,%d1
78	swap	%d1
79	orl	%d1,%d0			|put it in the right place
80	bfextu	CMDREG1B(%a6){#10:#3},%d1	|extract bit 3,4,5
81	lsll	#2,%d1
82	swap	%d1
83	orl	%d1,%d0			|put them in the right place
84	movel	%d0,CMDREG3B(%a1)		|in the busy frame
85|
86| Or in the FPSR from the emulation with the USER_FPSR on the stack.
87|
88	fmovel	%FPSR,%d0
89	orl	%d0,USER_FPSR(%a6)
90	movel	USER_FPSR(%a6),FPSR_SHADOW(%a1) |set exc bits
91	orl	#sx_mask,E_BYTE(%a1)
92	bra	do_clean
93
94|
95| Frame is an unimp frame possible resulting from an fmove <ea>,fp0
96| that caused an exception
97|
98| a1 is modified to point into the new frame allowing fpsp equates
99| to be valid.
100|
101unimp_x:
102	cmpib	#UNIMP_40_SIZE-4,1(%a7)	|test for orig unimp frame
103	bnes	test_rev
104	leal	UNIMP_40_SIZE+LOCAL_SIZE(%a7),%a1
105	bras	unimp_con
106test_rev:
107	cmpib	#UNIMP_41_SIZE-4,1(%a7)	|test for rev unimp frame
108	bnel	fpsp_fmt_error		|if not $28 or $30
109	leal	UNIMP_41_SIZE+LOCAL_SIZE(%a7),%a1
110
111unimp_con:
112|
113| Fix up the new unimp frame with entries from the old unimp frame
114|
115	movel	CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
116|
117| Or in the FPSR from the emulation with the USER_FPSR on the stack.
118|
119	fmovel	%FPSR,%d0
120	orl	%d0,USER_FPSR(%a6)
121	bra	do_clean
122
123|
124| Frame is idle, so check for exceptions reported through
125| USER_FPSR and set the unimp frame accordingly.
126| A7 must be incremented to the point before the
127| idle fsave vector to the unimp vector.
128|
129
130do_check:
131	addl	#4,%a7			|point A7 back to unimp frame
132|
133| Or in the FPSR from the emulation with the USER_FPSR on the stack.
134|
135	fmovel	%FPSR,%d0
136	orl	%d0,USER_FPSR(%a6)
137|
138| On a busy frame, we must clear the nmnexc bits.
139|
140	cmpib	#BUSY_SIZE-4,1(%a7)	|check frame type
141	bnes	check_fr		|if busy, clr nmnexc
142	clrw	NMNEXC(%a6)		|clr nmnexc & nmcexc
143	btstb	#5,CMDREG1B(%a6)		|test for fmove out
144	bnes	frame_com
145	movel	USER_FPSR(%a6),FPSR_SHADOW(%a6) |set exc bits
146	orl	#sx_mask,E_BYTE(%a6)
147	bras	frame_com
148check_fr:
149	cmpb	#UNIMP_40_SIZE-4,1(%a7)
150	beqs	frame_com
151	clrw	NMNEXC(%a6)
152frame_com:
153	moveb	FPCR_ENABLE(%a6),%d0	|get fpcr enable byte
154	andb	FPSR_EXCEPT(%a6),%d0	|and in the fpsr exc byte
155	bfffo	%d0{#24:#8},%d1		|test for first set bit
156	leal	exc_tbl,%a0		|load jmp table address
157	subib	#24,%d1			|normalize bit offset to 0-8
158	movel	(%a0,%d1.w*4),%a0		|load routine address based
159|					;based on first enabled exc
160	jmp	(%a0)			|jump to routine
161|
162| Bsun is not possible in unimp or unsupp
163|
164bsun_exc:
165	bra	do_clean
166|
167| The typical work to be done to the unimp frame to report an
168| exception is to set the E1/E3 byte and clr the U flag.
169| commonE1 does this for E1 exceptions, which are snan,
170| operr, and dz.  commonE3 does this for E3 exceptions, which
171| are inex2 and inex1, and also clears the E1 exception bit
172| left over from the unimp exception.
173|
174commonE1:
175	bsetb	#E1,E_BYTE(%a6)		|set E1 flag
176	bra	commonE			|go clean and exit
177
178commonE3:
179	tstb	UFLG_TMP(%a6)		|test flag for unsup/unimp state
180	bnes	unsE3
181uniE3:
182	bsetb	#E3,E_BYTE(%a6)		|set E3 flag
183	bclrb	#E1,E_BYTE(%a6)		|clr E1 from unimp
184	bra	commonE
185
186unsE3:
187	tstb	RES_FLG(%a6)
188	bnes	unsE3_0
189unsE3_1:
190	bsetb	#E3,E_BYTE(%a6)		|set E3 flag
191unsE3_0:
192	bclrb	#E1,E_BYTE(%a6)		|clr E1 flag
193	movel	CMDREG1B(%a6),%d0
194	andl	#0x03c30000,%d0		|work for cmd3b
195	bfextu	CMDREG1B(%a6){#13:#1},%d1	|extract bit 2
196	lsll	#5,%d1
197	swap	%d1
198	orl	%d1,%d0			|put it in the right place
199	bfextu	CMDREG1B(%a6){#10:#3},%d1	|extract bit 3,4,5
200	lsll	#2,%d1
201	swap	%d1
202	orl	%d1,%d0			|put them in the right place
203	movel	%d0,CMDREG3B(%a6)		|in the busy frame
204
205commonE:
206	bclrb	#UFLAG,T_BYTE(%a6)	|clr U flag from unimp
207	bra	do_clean		|go clean and exit
208|
209| No bits in the enable byte match existing exceptions.  Check for
210| the case of the ovfl exc without the ovfl enabled, but with
211| inex2 enabled.
212|
213no_match:
214	btstb	#inex2_bit,FPCR_ENABLE(%a6) |check for ovfl/inex2 case
215	beqs	no_exc			|if clear, exit
216	btstb	#ovfl_bit,FPSR_EXCEPT(%a6) |now check ovfl
217	beqs	no_exc			|if clear, exit
218	bras	ovfl_unfl		|go to unfl_ovfl to determine if
219|					;it is an unsupp or unimp exc
220
221| No exceptions are to be reported.  If the instruction was
222| unimplemented, no FPU restore is necessary.  If it was
223| unsupported, we must perform the restore.
224no_exc:
225	tstb	UFLG_TMP(%a6)	|test flag for unsupp/unimp state
226	beqs	uni_no_exc
227uns_no_exc:
228	tstb	RES_FLG(%a6)	|check if frestore is needed
229	bne	do_clean	|if clear, no frestore needed
230uni_no_exc:
231	moveml	USER_DA(%a6),%d0-%d1/%a0-%a1
232	fmovemx USER_FP0(%a6),%fp0-%fp3
233	fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
234	unlk	%a6
235	bra	finish_up
236|
237| Unsupported Data Type Handler:
238| Ovfl:
239|   An fmoveout that results in an overflow is reported this way.
240| Unfl:
241|   An fmoveout that results in an underflow is reported this way.
242|
243| Unimplemented Instruction Handler:
244| Ovfl:
245|   Only scosh, setox, ssinh, stwotox, and scale can set overflow in
246|   this manner.
247| Unfl:
248|   Stwotox, setox, and scale can set underflow in this manner.
249|   Any of the other Library Routines such that f(x)=x in which
250|   x is an extended denorm can report an underflow exception.
251|   It is the responsibility of the exception-causing exception
252|   to make sure that WBTEMP is correct.
253|
254|   The exceptional operand is in FP_SCR1.
255|
256ovfl_unfl:
257	tstb	UFLG_TMP(%a6)	|test flag for unsupp/unimp state
258	beqs	ofuf_con
259|
260| The caller was from an unsupported data type trap.  Test if the
261| caller set CU_ONLY.  If so, the exceptional operand is expected in
262| FPTEMP, rather than WBTEMP.
263|
264	tstb	CU_ONLY(%a6)		|test if inst is cu-only
265	beq	unsE3
266|	move.w	#$fe,CU_SAVEPC(%a6)
267	clrb	CU_SAVEPC(%a6)
268	bsetb	#E1,E_BYTE(%a6)		|set E1 exception flag
269	movew	ETEMP_EX(%a6),FPTEMP_EX(%a6)
270	movel	ETEMP_HI(%a6),FPTEMP_HI(%a6)
271	movel	ETEMP_LO(%a6),FPTEMP_LO(%a6)
272	bsetb	#fptemp15_bit,DTAG(%a6)	|set fpte15
273	bclrb	#UFLAG,T_BYTE(%a6)	|clr U flag from unimp
274	bra	do_clean		|go clean and exit
275
276ofuf_con:
277	moveb	(%a7),VER_TMP(%a6)	|save version number
278	cmpib	#BUSY_SIZE-4,1(%a7)	|check for busy frame
279	beqs	busy_fr			|if unimp, grow to busy
280	cmpib	#VER_40,(%a7)		|test for orig unimp frame
281	bnes	try_41			|if not, test for rev frame
282	moveql	#13,%d0			|need to zero 14 lwords
283	bras	ofuf_fin
284try_41:
285	cmpib	#VER_41,(%a7)		|test for rev unimp frame
286	bnel	fpsp_fmt_error		|if neither, exit with error
287	moveql	#11,%d0			|need to zero 12 lwords
288
289ofuf_fin:
290	clrl	(%a7)
291loop1:
292	clrl	-(%a7)			|clear and dec a7
293	dbra	%d0,loop1
294	moveb	VER_TMP(%a6),(%a7)
295	moveb	#BUSY_SIZE-4,1(%a7)		|write busy fmt word.
296busy_fr:
297	movel	FP_SCR1(%a6),WBTEMP_EX(%a6)	|write
298	movel	FP_SCR1+4(%a6),WBTEMP_HI(%a6)	|exceptional op to
299	movel	FP_SCR1+8(%a6),WBTEMP_LO(%a6)	|wbtemp
300	bsetb	#E3,E_BYTE(%a6)			|set E3 flag
301	bclrb	#E1,E_BYTE(%a6)			|make sure E1 is clear
302	bclrb	#UFLAG,T_BYTE(%a6)		|clr U flag
303	movel	USER_FPSR(%a6),FPSR_SHADOW(%a6)
304	orl	#sx_mask,E_BYTE(%a6)
305	movel	CMDREG1B(%a6),%d0		|fix cmd1b to make it
306	andl	#0x03c30000,%d0		|work for cmd3b
307	bfextu	CMDREG1B(%a6){#13:#1},%d1	|extract bit 2
308	lsll	#5,%d1
309	swap	%d1
310	orl	%d1,%d0			|put it in the right place
311	bfextu	CMDREG1B(%a6){#10:#3},%d1	|extract bit 3,4,5
312	lsll	#2,%d1
313	swap	%d1
314	orl	%d1,%d0			|put them in the right place
315	movel	%d0,CMDREG3B(%a6)		|in the busy frame
316
317|
318| Check if the frame to be restored is busy or unimp.
319|** NOTE *** Bug fix for errata (0d43b #3)
320| If the frame is unimp, we must create a busy frame to
321| fix the bug with the nmnexc bits in cases in which they
322| are set by a previous instruction and not cleared by
323| the save. The frame will be unimp only if the final
324| instruction in an emulation routine caused the exception
325| by doing an fmove <ea>,fp0.  The exception operand, in
326| internal format, is in fptemp.
327|
328do_clean:
329	cmpib	#UNIMP_40_SIZE-4,1(%a7)
330	bnes	do_con
331	moveql	#13,%d0			|in orig, need to zero 14 lwords
332	bras	do_build
333do_con:
334	cmpib	#UNIMP_41_SIZE-4,1(%a7)
335	bnes	do_restore		|frame must be busy
336	moveql	#11,%d0			|in rev, need to zero 12 lwords
337
338do_build:
339	moveb	(%a7),VER_TMP(%a6)
340	clrl	(%a7)
341loop2:
342	clrl	-(%a7)			|clear and dec a7
343	dbra	%d0,loop2
344|
345| Use a1 as pointer into new frame.  a6 is not correct if an unimp or
346| busy frame was created as the result of an exception on the final
347| instruction of an emulation routine.
348|
349| We need to set the nmcexc bits if the exception is E1. Otherwise,
350| the exc taken will be inex2.
351|
352	leal	BUSY_SIZE+LOCAL_SIZE(%a7),%a1	|init a1 for new frame
353	moveb	VER_TMP(%a6),(%a7)	|write busy fmt word
354	moveb	#BUSY_SIZE-4,1(%a7)
355	movel	FP_SCR1(%a6),WBTEMP_EX(%a1)	|write
356	movel	FP_SCR1+4(%a6),WBTEMP_HI(%a1)	|exceptional op to
357	movel	FP_SCR1+8(%a6),WBTEMP_LO(%a1)	|wbtemp
358|	btst.b	#E1,E_BYTE(%a1)
359|	beq.b	do_restore
360	bfextu	USER_FPSR(%a6){#17:#4},%d0	|get snan/operr/ovfl/unfl bits
361	bfins	%d0,NMCEXC(%a1){#4:#4}	|and insert them in nmcexc
362	movel	USER_FPSR(%a6),FPSR_SHADOW(%a1) |set exc bits
363	orl	#sx_mask,E_BYTE(%a1)
364
365do_restore:
366	moveml	USER_DA(%a6),%d0-%d1/%a0-%a1
367	fmovemx USER_FP0(%a6),%fp0-%fp3
368	fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
369	frestore (%a7)+
370	tstb	RES_FLG(%a6)	|RES_FLG indicates a "continuation" frame
371	beq	cont
372	bsr	bug1384
373cont:
374	unlk	%a6
375|
376| If trace mode enabled, then go to trace handler.  This handler
377| cannot have any fp instructions.  If there are fp inst's and an
378| exception has been restored into the machine then the exception
379| will occur upon execution of the fp inst.  This is not desirable
380| in the kernel (supervisor mode).  See MC68040 manual Section 9.3.8.
381|
382finish_up:
383	btstb	#7,(%a7)		|test T1 in SR
384	bnes	g_trace
385	btstb	#6,(%a7)		|test T0 in SR
386	bnes	g_trace
387	bral	fpsp_done
388|
389| Change integer stack to look like trace stack
390| The address of the instruction that caused the
391| exception is already in the integer stack (is
392| the same as the saved friar)
393|
394| If the current frame is already a 6-word stack then all
395| that needs to be done is to change the vector# to TRACE.
396| If the frame is only a 4-word stack (meaning we got here
397| on an Unsupported data type exception), then we need to grow
398| the stack an extra 2 words and get the FPIAR from the FPU.
399|
400g_trace:
401	bftst	EXC_VEC-4(%sp){#0:#4}
402	bne	g_easy
403
404	subw	#4,%sp		| make room
405	movel	4(%sp),(%sp)
406	movel	8(%sp),4(%sp)
407	subw	#BUSY_SIZE,%sp
408	fsave	(%sp)
409	fmovel	%fpiar,BUSY_SIZE+EXC_EA-4(%sp)
410	frestore (%sp)
411	addw	#BUSY_SIZE,%sp
412
413g_easy:
414	movew	#TRACE_VEC,EXC_VEC-4(%a7)
415	bral	real_trace
416|
417|  This is a work-around for hardware bug 1384.
418|
419bug1384:
420	link	%a5,#0
421	fsave	-(%sp)
422	cmpib	#0x41,(%sp)	| check for correct frame
423	beq	frame_41
424	bgt	nofix		| if more advanced mask, do nada
425
426frame_40:
427	tstb	1(%sp)		| check to see if idle
428	bne	notidle
429idle40:
430	clrl	(%sp)		| get rid of old fsave frame
431        movel  %d1,USER_D1(%a6)  | save d1
432	movew	#8,%d1		| place unimp frame instead
433loop40:	clrl	-(%sp)
434	dbra	%d1,loop40
435        movel  USER_D1(%a6),%d1  | restore d1
436	movel	#0x40280000,-(%sp)
437	frestore (%sp)+
438	unlk	%a5
439	rts
440
441frame_41:
442	tstb	1(%sp)		| check to see if idle
443	bne	notidle
444idle41:
445	clrl	(%sp)		| get rid of old fsave frame
446        movel  %d1,USER_D1(%a6)  | save d1
447	movew	#10,%d1		| place unimp frame instead
448loop41:	clrl	-(%sp)
449	dbra	%d1,loop41
450        movel  USER_D1(%a6),%d1  | restore d1
451	movel	#0x41300000,-(%sp)
452	frestore (%sp)+
453	unlk	%a5
454	rts
455
456notidle:
457	bclrb	#etemp15_bit,-40(%a5)
458	frestore (%sp)+
459	unlk	%a5
460	rts
461
462nofix:
463	frestore (%sp)+
464	unlk	%a5
465	rts
466
467	|end
468