summaryrefslogtreecommitdiffstats
path: root/arch/m68k/fpsp040/skeleton.S
blob: 1e4d0cf720accca4eb5e19269aa1b2c777ff6ad9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
|
|	skeleton.sa 3.2 4/26/91
|
|	This file contains code that is system dependent and will
|	need to be modified to install the FPSP.
|
|	Each entry point for exception 'xxxx' begins with a 'jmp fpsp_xxxx'.
|	Put any target system specific handling that must be done immediately
|	before the jump instruction.  If there no handling necessary, then
|	the 'fpsp_xxxx' handler entry point should be placed in the exception
|	table so that the 'jmp' can be eliminated. If the FPSP determines that the
|	exception is one that must be reported then there will be a
|	return from the package by a 'jmp real_xxxx'.  At that point
|	the machine state will be identical to the state before
|	the FPSP was entered.  In particular, whatever condition
|	that caused the exception will still be pending when the FPSP
|	package returns.  Thus, there will be system specific code
|	to handle the exception.
|
|	If the exception was completely handled by the package, then
|	the return will be via a 'jmp fpsp_done'.  Unless there is 
|	OS specific work to be done (such as handling a context switch or
|	interrupt) the user program can be resumed via 'rte'.
|
|	In the following skeleton code, some typical 'real_xxxx' handling
|	code is shown.  This code may need to be moved to an appropriate
|	place in the target system, or rewritten.
|	

|		Copyright (C) Motorola, Inc. 1990
|			All Rights Reserved
|
|	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA 
|	The copyright notice above does not evidence any  
|	actual or intended publication of such source code.

|
|	Modified for Linux-1.3.x by Jes Sorensen (jds@kom.auc.dk)
|

#include <linux/linkage.h>
#include <asm/entry.h>

|SKELETON	idnt    2,1 | Motorola 040 Floating Point Software Package

	|section 15
|
|	The following counters are used for standalone testing
|

	|section 8
 
	.include "fpsp.h"

	|xref	b1238_fix

|
|	Divide by Zero exception
|
|	All dz exceptions are 'real', hence no fpsp_dz entry point.
|
	.global	dz
	.global	real_dz
dz:
real_dz:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E1,E_BYTE(%a6)
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)

|
|	Inexact exception
|
|	All inexact exceptions are real, but the 'real' handler
|	will probably want to clear the pending exception.
|	The provided code will clear the E3 exception (if pending), 
|	otherwise clear the E1 exception.  The frestore is not really
|	necessary for E1 exceptions.
|
| Code following the 'inex' label is to handle bug #1232.  In this
| bug, if an E1 snan, ovfl, or unfl occurred, and the process was
| swapped out before taking the exception, the exception taken on
| return was inex, rather than the correct exception.  The snan, ovfl,
| and unfl exception to be taken must not have been enabled.  The
| fix is to check for E1, and the existence of one of snan, ovfl,
| or unfl bits set in the fpsr.  If any of these are set, branch
| to the appropriate  handler for the exception in the fpsr.  Note
| that this fix is only for d43b parts, and is skipped if the
| version number is not $40.
| 
|
	.global	real_inex
	.global	inex
inex:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	cmpib		#VER_40,(%sp)		|test version number
	bnes		not_fmt40
	fmovel		%fpsr,-(%sp)
	btstb		#E1,E_BYTE(%a6)		|test for E1 set
	beqs		not_b1232
	btstb		#snan_bit,2(%sp) |test for snan
	beq		inex_ckofl
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6
	bra		snan
inex_ckofl:
	btstb		#ovfl_bit,2(%sp) |test for ovfl
	beq		inex_ckufl 
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6
	bra		ovfl
inex_ckufl:
	btstb		#unfl_bit,2(%sp) |test for unfl
	beq		not_b1232
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6
	bra		unfl

|
| We do not have the bug 1232 case.  Clean up the stack and call
| real_inex.
|
not_b1232:
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6

real_inex:

	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
not_fmt40:
	bclrb		#E3,E_BYTE(%a6)		|clear and test E3 flag
	beqs		inex_cke1
|
| Clear dirty bit on dest resister in the frame before branching
| to b1238_fix.
|
	moveml		%d0/%d1,USER_DA(%a6)
	bfextu		CMDREG1B(%a6){#6:#3},%d0		|get dest reg no
	bclrb		%d0,FPR_DIRTY_BITS(%a6)	|clr dest dirty bit
	bsrl		b1238_fix		|test for bug1238 case
	moveml		USER_DA(%a6),%d0/%d1
	bras		inex_done
inex_cke1:
	bclrb		#E1,E_BYTE(%a6)
inex_done:
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)
	
|
|	Overflow exception
|
	|xref	fpsp_ovfl
	.global	real_ovfl
	.global	ovfl
ovfl:
	jmp	fpsp_ovfl
real_ovfl:

	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E3,E_BYTE(%a6)		|clear and test E3 flag
	bnes		ovfl_done
	bclrb		#E1,E_BYTE(%a6)
ovfl_done:
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)
	
|
|	Underflow exception
|
	|xref	fpsp_unfl
	.global	real_unfl
	.global	unfl
unfl:
	jmp	fpsp_unfl
real_unfl:

	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E3,E_BYTE(%a6)		|clear and test E3 flag
	bnes		unfl_done
	bclrb		#E1,E_BYTE(%a6)
unfl_done:
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)
	
|
|	Signalling NAN exception
|
	|xref	fpsp_snan
	.global	real_snan
	.global	snan
snan:
	jmp	fpsp_snan
real_snan:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E1,E_BYTE(%a6)	|snan is always an E1 exception
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)
	
|
|	Operand Error exception
|
	|xref	fpsp_operr
	.global	real_operr
	.global	operr
operr:
	jmp	fpsp_operr
real_operr:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E1,E_BYTE(%a6)	|operr is always an E1 exception
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)

	
|
|	BSUN exception
|
|	This sample handler simply clears the nan bit in the FPSR.
|
	|xref	fpsp_bsun
	.global	real_bsun
	.global	bsun
bsun:
	jmp	fpsp_bsun
real_bsun:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E1,E_BYTE(%a6)	|bsun is always an E1 exception
	fmovel		%FPSR,-(%sp)
	bclrb		#nan_bit,(%sp)
	fmovel		(%sp)+,%FPSR
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)

|
|	F-line exception
|
|	A 'real' F-line exception is one that the FPSP isn't supposed to 
|	handle. E.g. an instruction with a co-processor ID that is not 1.
|
|
	|xref	fpsp_fline
	.global	real_fline
	.global	fline
fline:
	jmp	fpsp_fline
real_fline:

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)

|
|	Unsupported data type exception
|
	|xref	fpsp_unsupp
	.global	real_unsupp
	.global	unsupp
unsupp:
	jmp	fpsp_unsupp
real_unsupp:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E1,E_BYTE(%a6)	|unsupp is always an E1 exception
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	bral	SYMBOL_NAME(ret_from_exception)

|
|	Trace exception
|
	.global	real_trace
real_trace:
	|
	bral	SYMBOL_NAME(trap)

|
|	fpsp_fmt_error --- exit point for frame format error
|
|	The fpu stack frame does not match the frames existing
|	or planned at the time of this writing.  The fpsp is
|	unable to handle frame sizes not in the following
|	version:size pairs:
|
|	{4060, 4160} - busy frame
|	{4028, 4130} - unimp frame
|	{4000, 4100} - idle frame
|
|	This entry point simply holds an f-line illegal value.  
|	Replace this with a call to your kernel panic code or
|	code to handle future revisions of the fpu.
|
	.global	fpsp_fmt_error
fpsp_fmt_error:

	.long	0xf27f0000	|f-line illegal 

|
|	fpsp_done --- FPSP exit point
|
|	The exception has been handled by the package and we are ready
|	to return to user mode, but there may be OS specific code
|	to execute before we do.  If there is, do it now.
|
|

	.global	fpsp_done
fpsp_done:
	btst	#0x5,%sp@		| supervisor bit set in saved SR?
	beq	Lnotkern
	rte
Lnotkern:
	SAVE_ALL_INT
	GET_CURRENT(%d0)
	tstl	%curptr@(LTASK_NEEDRESCHED)
	jne	SYMBOL_NAME(ret_from_exception)	| deliver signals,
						| reschedule etc..
	RESTORE_ALL

|
|	mem_write --- write to user or supervisor address space
|
| Writes to memory while in supervisor mode.  copyout accomplishes
| this via a 'moves' instruction.  copyout is a UNIX SVR3 (and later) function.
| If you don't have copyout, use the local copy of the function below.
|
|	a0 - supervisor source address
|	a1 - user destination address
|	d0 - number of bytes to write (maximum count is 12)
|
| The supervisor source address is guaranteed to point into the supervisor
| stack.  The result is that a UNIX
| process is allowed to sleep as a consequence of a page fault during
| copyout.  The probability of a page fault is exceedingly small because
| the 68040 always reads the destination address and thus the page
| faults should have already been handled.
|
| If the EXC_SR shows that the exception was from supervisor space,
| then just do a dumb (and slow) memory move.  In a UNIX environment
| there shouldn't be any supervisor mode floating point exceptions.
|
	.global	mem_write
mem_write:
	btstb	#5,EXC_SR(%a6)	|check for supervisor state
	beqs	user_write
super_write:
	moveb	(%a0)+,(%a1)+
	subql	#1,%d0
	bnes	super_write
	rts
user_write:
	movel	%d1,-(%sp)	|preserve d1 just in case
	movel	%d0,-(%sp)
	movel	%a1,-(%sp)
	movel	%a0,-(%sp)
	jsr		copyout
	addw	#12,%sp
	movel	(%sp)+,%d1
	rts
|
|	mem_read --- read from user or supervisor address space
|
| Reads from memory while in supervisor mode.  copyin accomplishes
| this via a 'moves' instruction.  copyin is a UNIX SVR3 (and later) function.
| If you don't have copyin, use the local copy of the function below.
|
| The FPSP calls mem_read to read the original F-line instruction in order
| to extract the data register number when the 'Dn' addressing mode is
| used.
|
|Input:
|	a0 - user source address
|	a1 - supervisor destination address
|	d0 - number of bytes to read (maximum count is 12)
|
| Like mem_write, mem_read always reads with a supervisor 
| destination address on the supervisor stack.  Also like mem_write,
| the EXC_SR is checked and a simple memory copy is done if reading
| from supervisor space is indicated.
|
	.global	mem_read
mem_read:
	btstb	#5,EXC_SR(%a6)	|check for supervisor state
	beqs	user_read
super_read:
	moveb	(%a0)+,(%a1)+
	subql	#1,%d0
	bnes	super_read
	rts
user_read:
	movel	%d1,-(%sp)	|preserve d1 just in case
	movel	%d0,-(%sp)
	movel	%a1,-(%sp)
	movel	%a0,-(%sp)
	jsr	copyin
	addw	#12,%sp
	movel	(%sp)+,%d1
	rts

|
| Use these routines if your kernel doesn't have copyout/copyin equivalents.
| Assumes that D0/D1/A0/A1 are scratch registers. copyout overwrites DFC,
| and copyin overwrites SFC.
|
copyout:
	movel	4(%sp),%a0	| source
	movel	8(%sp),%a1	| destination
	movel	12(%sp),%d0	| count
	subl	#1,%d0		| dec count by 1 for dbra
	movel	#1,%d1

|	DFC is already set
|	movec	%d1,%DFC		| set dfc for user data space
moreout:
	moveb	(%a0)+,%d1	| fetch supervisor byte
out_ea:
	movesb	%d1,(%a1)+	| write user byte
	dbf	%d0,moreout
	rts

copyin:
	movel	4(%sp),%a0	| source
	movel	8(%sp),%a1	| destination
	movel	12(%sp),%d0	| count
	subl	#1,%d0		| dec count by 1 for dbra
	movel	#1,%d1
|	SFC is already set
|	movec	%d1,%SFC		| set sfc for user space
morein:
in_ea:
	movesb	(%a0)+,%d1	| fetch user byte
	moveb	%d1,(%a1)+	| write supervisor byte
	dbf	%d0,morein
	rts

	.section .fixup,#alloc,#execinstr
	.even
1:
	jbra	SYMBOL_NAME(fpsp040_die)

	.section __ex_table,#alloc
	.align	4

	.long	in_ea,1b
	.long	out_ea,1b

	|end