xref: /openbmc/linux/arch/m68k/fpsp040/bugfix.S (revision e00d82d0)
1|
2|	bugfix.sa 3.2 1/31/91
3|
4|
5|	This file contains workarounds for bugs in the 040
6|	relating to the Floating-Point Software Package (FPSP)
7|
8|	Fixes for bugs: 1238
9|
10|	Bug: 1238
11|
12|
13|    /* The following dirty_bit clear should be left in
14|     * the handler permanently to improve throughput.
15|     * The dirty_bits are located at bits [23:16] in
16|     * longword $08 in the busy frame $4x60.  Bit 16
17|     * corresponds to FP0, bit 17 corresponds to FP1,
18|     * and so on.
19|     */
20|    if  (E3_exception_just_serviced)   {
21|         dirty_bit[cmdreg3b[9:7]] = 0;
22|         }
23|
24|    if  (fsave_format_version != $40)  {goto NOFIX}
25|
26|    if !(E3_exception_just_serviced)   {goto NOFIX}
27|    if  (cupc == 0000000)              {goto NOFIX}
28|    if  ((cmdreg1b[15:13] != 000) &&
29|         (cmdreg1b[15:10] != 010001))  {goto NOFIX}
30|    if (((cmdreg1b[15:13] != 000) || ((cmdreg1b[12:10] != cmdreg2b[9:7]) &&
31|				      (cmdreg1b[12:10] != cmdreg3b[9:7]))  ) &&
32|	 ((cmdreg1b[ 9: 7] != cmdreg2b[9:7]) &&
33|	  (cmdreg1b[ 9: 7] != cmdreg3b[9:7])) )  {goto NOFIX}
34|
35|    /* Note: for 6d43b or 8d43b, you may want to add the following code
36|     * to get better coverage.  (If you do not insert this code, the part
37|     * won't lock up; it will simply get the wrong answer.)
38|     * Do NOT insert this code for 10d43b or later parts.
39|     *
40|     *  if (fpiarcu == integer stack return address) {
41|     *       cupc = 0000000;
42|     *       goto NOFIX;
43|     *       }
44|     */
45|
46|    if (cmdreg1b[15:13] != 000)   {goto FIX_OPCLASS2}
47|    FIX_OPCLASS0:
48|    if (((cmdreg1b[12:10] == cmdreg2b[9:7]) ||
49|	 (cmdreg1b[ 9: 7] == cmdreg2b[9:7])) &&
50|	(cmdreg1b[12:10] != cmdreg3b[9:7]) &&
51|	(cmdreg1b[ 9: 7] != cmdreg3b[9:7]))  {  /* xu conflict only */
52|	/* We execute the following code if there is an
53|	   xu conflict and NOT an nu conflict */
54|
55|	/* first save some values on the fsave frame */
56|	stag_temp     = STAG[fsave_frame];
57|	cmdreg1b_temp = CMDREG1B[fsave_frame];
58|	dtag_temp     = DTAG[fsave_frame];
59|	ete15_temp    = ETE15[fsave_frame];
60|
61|	CUPC[fsave_frame] = 0000000;
62|	FRESTORE
63|	FSAVE
64|
65|	/* If the xu instruction is exceptional, we punt.
66|	 * Otherwise, we would have to include OVFL/UNFL handler
67|	 * code here to get the correct answer.
68|	 */
69|	if (fsave_frame_format == $4060) {goto KILL_PROCESS}
70|
71|	fsave_frame = /* build a long frame of all zeros */
72|	fsave_frame_format = $4060;  /* label it as long frame */
73|
74|	/* load it with the temps we saved */
75|	STAG[fsave_frame]     =  stag_temp;
76|	CMDREG1B[fsave_frame] =  cmdreg1b_temp;
77|	DTAG[fsave_frame]     =  dtag_temp;
78|	ETE15[fsave_frame]    =  ete15_temp;
79|
80|	/* Make sure that the cmdreg3b dest reg is not going to
81|	 * be destroyed by a FMOVEM at the end of all this code.
82|	 * If it is, you should move the current value of the reg
83|	 * onto the stack so that the reg will loaded with that value.
84|	 */
85|
86|	/* All done.  Proceed with the code below */
87|    }
88|
89|    etemp  = FP_reg_[cmdreg1b[12:10]];
90|    ete15  = ~ete14;
91|    cmdreg1b[15:10] = 010010;
92|    clear(bug_flag_procIDxxxx);
93|    FRESTORE and return;
94|
95|
96|    FIX_OPCLASS2:
97|    if ((cmdreg1b[9:7] == cmdreg2b[9:7]) &&
98|	(cmdreg1b[9:7] != cmdreg3b[9:7]))  {  /* xu conflict only */
99|	/* We execute the following code if there is an
100|	   xu conflict and NOT an nu conflict */
101|
102|	/* first save some values on the fsave frame */
103|	stag_temp     = STAG[fsave_frame];
104|	cmdreg1b_temp = CMDREG1B[fsave_frame];
105|	dtag_temp     = DTAG[fsave_frame];
106|	ete15_temp    = ETE15[fsave_frame];
107|	etemp_temp    = ETEMP[fsave_frame];
108|
109|	CUPC[fsave_frame] = 0000000;
110|	FRESTORE
111|	FSAVE
112|
113|
114|	/* If the xu instruction is exceptional, we punt.
115|	 * Otherwise, we would have to include OVFL/UNFL handler
116|	 * code here to get the correct answer.
117|	 */
118|	if (fsave_frame_format == $4060) {goto KILL_PROCESS}
119|
120|	fsave_frame = /* build a long frame of all zeros */
121|	fsave_frame_format = $4060;  /* label it as long frame */
122|
123|	/* load it with the temps we saved */
124|	STAG[fsave_frame]     =  stag_temp;
125|	CMDREG1B[fsave_frame] =  cmdreg1b_temp;
126|	DTAG[fsave_frame]     =  dtag_temp;
127|	ETE15[fsave_frame]    =  ete15_temp;
128|	ETEMP[fsave_frame]    =  etemp_temp;
129|
130|	/* Make sure that the cmdreg3b dest reg is not going to
131|	 * be destroyed by a FMOVEM at the end of all this code.
132|	 * If it is, you should move the current value of the reg
133|	 * onto the stack so that the reg will loaded with that value.
134|	 */
135|
136|	/* All done.  Proceed with the code below */
137|    }
138|
139|    if (etemp_exponent == min_sgl)   etemp_exponent = min_dbl;
140|    if (etemp_exponent == max_sgl)   etemp_exponent = max_dbl;
141|    cmdreg1b[15:10] = 010101;
142|    clear(bug_flag_procIDxxxx);
143|    FRESTORE and return;
144|
145|
146|    NOFIX:
147|    clear(bug_flag_procIDxxxx);
148|    FRESTORE and return;
149|
150
151
152|		Copyright (C) Motorola, Inc. 1990
153|			All Rights Reserved
154|
155|       For details on the license for this file, please see the
156|       file, README, in this same directory.
157
158|BUGFIX    idnt    2,1 | Motorola 040 Floating Point Software Package
159
160	|section	8
161
162#include "fpsp.h"
163
164	|xref	fpsp_fmt_error
165
166	.global	b1238_fix
167b1238_fix:
168|
169| This code is entered only on completion of the handling of an
170| nu-generated ovfl, unfl, or inex exception.  If the version
171| number of the fsave is not $40, this handler is not necessary.
172| Simply branch to fix_done and exit normally.
173|
174	cmpib	#VER_40,4(%a7)
175	bne	fix_done
176|
177| Test for cu_savepc equal to zero.  If not, this is not a bug
178| #1238 case.
179|
180	moveb	CU_SAVEPC(%a6),%d0
181	andib	#0xFE,%d0
182	beq	fix_done	|if zero, this is not bug #1238
183
184|
185| Test the register conflict aspect.  If opclass0, check for
186| cu src equal to xu dest or equal to nu dest.  If so, go to
187| op0.  Else, or if opclass2, check for cu dest equal to
188| xu dest or equal to nu dest.  If so, go to tst_opcl.  Else,
189| exit, it is not the bug case.
190|
191| Check for opclass 0.  If not, go and check for opclass 2 and sgl.
192|
193	movew	CMDREG1B(%a6),%d0
194	andiw	#0xE000,%d0		|strip all but opclass
195	bne	op2sgl			|not opclass 0, check op2
196|
197| Check for cu and nu register conflict.  If one exists, this takes
198| priority over a cu and xu conflict.
199|
200	bfextu	CMDREG1B(%a6){#3:#3},%d0	|get 1st src
201	bfextu	CMDREG3B(%a6){#6:#3},%d1	|get 3rd dest
202	cmpb	%d0,%d1
203	beqs	op0			|if equal, continue bugfix
204|
205| Check for cu dest equal to nu dest.  If so, go and fix the
206| bug condition.  Otherwise, exit.
207|
208	bfextu	CMDREG1B(%a6){#6:#3},%d0	|get 1st dest
209	cmpb	%d0,%d1			|cmp 1st dest with 3rd dest
210	beqs	op0			|if equal, continue bugfix
211|
212| Check for cu and xu register conflict.
213|
214	bfextu	CMDREG2B(%a6){#6:#3},%d1	|get 2nd dest
215	cmpb	%d0,%d1			|cmp 1st dest with 2nd dest
216	beqs	op0_xu			|if equal, continue bugfix
217	bfextu	CMDREG1B(%a6){#3:#3},%d0	|get 1st src
218	cmpb	%d0,%d1			|cmp 1st src with 2nd dest
219	beq	op0_xu
220	bne	fix_done		|if the reg checks fail, exit
221|
222| We have the opclass 0 situation.
223|
224op0:
225	bfextu	CMDREG1B(%a6){#3:#3},%d0	|get source register no
226	movel	#7,%d1
227	subl	%d0,%d1
228	clrl	%d0
229	bsetl	%d1,%d0
230	fmovemx %d0,ETEMP(%a6)		|load source to ETEMP
231
232	moveb	#0x12,%d0
233	bfins	%d0,CMDREG1B(%a6){#0:#6}	|opclass 2, extended
234|
235|	Set ETEMP exponent bit 15 as the opposite of ete14
236|
237	btst	#6,ETEMP_EX(%a6)		|check etemp exponent bit 14
238	beq	setete15
239	bclr	#etemp15_bit,STAG(%a6)
240	bra	finish
241setete15:
242	bset	#etemp15_bit,STAG(%a6)
243	bra	finish
244
245|
246| We have the case in which a conflict exists between the cu src or
247| dest and the dest of the xu.  We must clear the instruction in
248| the cu and restore the state, allowing the instruction in the
249| xu to complete.  Remember, the instruction in the nu
250| was exceptional, and was completed by the appropriate handler.
251| If the result of the xu instruction is not exceptional, we can
252| restore the instruction from the cu to the frame and continue
253| processing the original exception.  If the result is also
254| exceptional, we choose to kill the process.
255|
256|	Items saved from the stack:
257|
258|		$3c stag     - L_SCR1
259|		$40 cmdreg1b - L_SCR2
260|		$44 dtag     - L_SCR3
261|
262| The cu savepc is set to zero, and the frame is restored to the
263| fpu.
264|
265op0_xu:
266	movel	STAG(%a6),L_SCR1(%a6)
267	movel	CMDREG1B(%a6),L_SCR2(%a6)
268	movel	DTAG(%a6),L_SCR3(%a6)
269	andil	#0xe0000000,L_SCR3(%a6)
270	moveb	#0,CU_SAVEPC(%a6)
271	movel	(%a7)+,%d1		|save return address from bsr
272	frestore (%a7)+
273	fsave	-(%a7)
274|
275| Check if the instruction which just completed was exceptional.
276|
277	cmpw	#0x4060,(%a7)
278	beq	op0_xb
279|
280| It is necessary to isolate the result of the instruction in the
281| xu if it is to fp0 - fp3 and write that value to the USER_FPn
282| locations on the stack.  The correct destination register is in
283| cmdreg2b.
284|
285	bfextu	CMDREG2B(%a6){#6:#3},%d0	|get dest register no
286	cmpil	#3,%d0
287	bgts	op0_xi
288	beqs	op0_fp3
289	cmpil	#1,%d0
290	blts	op0_fp0
291	beqs	op0_fp1
292op0_fp2:
293	fmovemx %fp2-%fp2,USER_FP2(%a6)
294	bras	op0_xi
295op0_fp1:
296	fmovemx %fp1-%fp1,USER_FP1(%a6)
297	bras	op0_xi
298op0_fp0:
299	fmovemx %fp0-%fp0,USER_FP0(%a6)
300	bras	op0_xi
301op0_fp3:
302	fmovemx %fp3-%fp3,USER_FP3(%a6)
303|
304| The frame returned is idle.  We must build a busy frame to hold
305| the cu state information and setup etemp.
306|
307op0_xi:
308	movel	#22,%d0		|clear 23 lwords
309	clrl	(%a7)
310op0_loop:
311	clrl	-(%a7)
312	dbf	%d0,op0_loop
313	movel	#0x40600000,-(%a7)
314	movel	L_SCR1(%a6),STAG(%a6)
315	movel	L_SCR2(%a6),CMDREG1B(%a6)
316	movel	L_SCR3(%a6),DTAG(%a6)
317	moveb	#0x6,CU_SAVEPC(%a6)
318	movel	%d1,-(%a7)		|return bsr return address
319	bfextu	CMDREG1B(%a6){#3:#3},%d0	|get source register no
320	movel	#7,%d1
321	subl	%d0,%d1
322	clrl	%d0
323	bsetl	%d1,%d0
324	fmovemx %d0,ETEMP(%a6)		|load source to ETEMP
325
326	moveb	#0x12,%d0
327	bfins	%d0,CMDREG1B(%a6){#0:#6}	|opclass 2, extended
328|
329|	Set ETEMP exponent bit 15 as the opposite of ete14
330|
331	btst	#6,ETEMP_EX(%a6)		|check etemp exponent bit 14
332	beq	op0_sete15
333	bclr	#etemp15_bit,STAG(%a6)
334	bra	finish
335op0_sete15:
336	bset	#etemp15_bit,STAG(%a6)
337	bra	finish
338
339|
340| The frame returned is busy.  It is not possible to reconstruct
341| the code sequence to allow completion.  We will jump to
342| fpsp_fmt_error and allow the kernel to kill the process.
343|
344op0_xb:
345	jmp	fpsp_fmt_error
346
347|
348| Check for opclass 2 and single size.  If not both, exit.
349|
350op2sgl:
351	movew	CMDREG1B(%a6),%d0
352	andiw	#0xFC00,%d0		|strip all but opclass and size
353	cmpiw	#0x4400,%d0		|test for opclass 2 and size=sgl
354	bne	fix_done		|if not, it is not bug 1238
355|
356| Check for cu dest equal to nu dest or equal to xu dest, with
357| a cu and nu conflict taking priority an nu conflict.  If either,
358| go and fix the bug condition.  Otherwise, exit.
359|
360	bfextu	CMDREG1B(%a6){#6:#3},%d0	|get 1st dest
361	bfextu	CMDREG3B(%a6){#6:#3},%d1	|get 3rd dest
362	cmpb	%d0,%d1			|cmp 1st dest with 3rd dest
363	beq	op2_com			|if equal, continue bugfix
364	bfextu	CMDREG2B(%a6){#6:#3},%d1	|get 2nd dest
365	cmpb	%d0,%d1			|cmp 1st dest with 2nd dest
366	bne	fix_done		|if the reg checks fail, exit
367|
368| We have the case in which a conflict exists between the cu src or
369| dest and the dest of the xu.  We must clear the instruction in
370| the cu and restore the state, allowing the instruction in the
371| xu to complete.  Remember, the instruction in the nu
372| was exceptional, and was completed by the appropriate handler.
373| If the result of the xu instruction is not exceptional, we can
374| restore the instruction from the cu to the frame and continue
375| processing the original exception.  If the result is also
376| exceptional, we choose to kill the process.
377|
378|	Items saved from the stack:
379|
380|		$3c stag     - L_SCR1
381|		$40 cmdreg1b - L_SCR2
382|		$44 dtag     - L_SCR3
383|		etemp        - FP_SCR2
384|
385| The cu savepc is set to zero, and the frame is restored to the
386| fpu.
387|
388op2_xu:
389	movel	STAG(%a6),L_SCR1(%a6)
390	movel	CMDREG1B(%a6),L_SCR2(%a6)
391	movel	DTAG(%a6),L_SCR3(%a6)
392	andil	#0xe0000000,L_SCR3(%a6)
393	moveb	#0,CU_SAVEPC(%a6)
394	movel	ETEMP(%a6),FP_SCR2(%a6)
395	movel	ETEMP_HI(%a6),FP_SCR2+4(%a6)
396	movel	ETEMP_LO(%a6),FP_SCR2+8(%a6)
397	movel	(%a7)+,%d1		|save return address from bsr
398	frestore (%a7)+
399	fsave	-(%a7)
400|
401| Check if the instruction which just completed was exceptional.
402|
403	cmpw	#0x4060,(%a7)
404	beq	op2_xb
405|
406| It is necessary to isolate the result of the instruction in the
407| xu if it is to fp0 - fp3 and write that value to the USER_FPn
408| locations on the stack.  The correct destination register is in
409| cmdreg2b.
410|
411	bfextu	CMDREG2B(%a6){#6:#3},%d0	|get dest register no
412	cmpil	#3,%d0
413	bgts	op2_xi
414	beqs	op2_fp3
415	cmpil	#1,%d0
416	blts	op2_fp0
417	beqs	op2_fp1
418op2_fp2:
419	fmovemx %fp2-%fp2,USER_FP2(%a6)
420	bras	op2_xi
421op2_fp1:
422	fmovemx %fp1-%fp1,USER_FP1(%a6)
423	bras	op2_xi
424op2_fp0:
425	fmovemx %fp0-%fp0,USER_FP0(%a6)
426	bras	op2_xi
427op2_fp3:
428	fmovemx %fp3-%fp3,USER_FP3(%a6)
429|
430| The frame returned is idle.  We must build a busy frame to hold
431| the cu state information and fix up etemp.
432|
433op2_xi:
434	movel	#22,%d0		|clear 23 lwords
435	clrl	(%a7)
436op2_loop:
437	clrl	-(%a7)
438	dbf	%d0,op2_loop
439	movel	#0x40600000,-(%a7)
440	movel	L_SCR1(%a6),STAG(%a6)
441	movel	L_SCR2(%a6),CMDREG1B(%a6)
442	movel	L_SCR3(%a6),DTAG(%a6)
443	moveb	#0x6,CU_SAVEPC(%a6)
444	movel	FP_SCR2(%a6),ETEMP(%a6)
445	movel	FP_SCR2+4(%a6),ETEMP_HI(%a6)
446	movel	FP_SCR2+8(%a6),ETEMP_LO(%a6)
447	movel	%d1,-(%a7)
448	bra	op2_com
449
450|
451| We have the opclass 2 single source situation.
452|
453op2_com:
454	moveb	#0x15,%d0
455	bfins	%d0,CMDREG1B(%a6){#0:#6}	|opclass 2, double
456
457	cmpw	#0x407F,ETEMP_EX(%a6)	|single +max
458	bnes	case2
459	movew	#0x43FF,ETEMP_EX(%a6)	|to double +max
460	bra	finish
461case2:
462	cmpw	#0xC07F,ETEMP_EX(%a6)	|single -max
463	bnes	case3
464	movew	#0xC3FF,ETEMP_EX(%a6)	|to double -max
465	bra	finish
466case3:
467	cmpw	#0x3F80,ETEMP_EX(%a6)	|single +min
468	bnes	case4
469	movew	#0x3C00,ETEMP_EX(%a6)	|to double +min
470	bra	finish
471case4:
472	cmpw	#0xBF80,ETEMP_EX(%a6)	|single -min
473	bne	fix_done
474	movew	#0xBC00,ETEMP_EX(%a6)	|to double -min
475	bra	finish
476|
477| The frame returned is busy.  It is not possible to reconstruct
478| the code sequence to allow completion.  fpsp_fmt_error causes
479| an fline illegal instruction to be executed.
480|
481| You should replace the jump to fpsp_fmt_error with a jump
482| to the entry point used to kill a process.
483|
484op2_xb:
485	jmp	fpsp_fmt_error
486
487|
488| Enter here if the case is not of the situations affected by
489| bug #1238, or if the fix is completed, and exit.
490|
491finish:
492fix_done:
493	rts
494
495	|end
496