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1|
2| skeleton.sa 3.2 4/26/91
3|
4| This file contains code that is system dependent and will
5| need to be modified to install the FPSP.
6|
7| Each entry point for exception 'xxxx' begins with a 'jmp fpsp_xxxx'.
8| Put any target system specific handling that must be done immediately
9| before the jump instruction. If there no handling necessary, then
10| the 'fpsp_xxxx' handler entry point should be placed in the exception
11| table so that the 'jmp' can be eliminated. If the FPSP determines that the
12| exception is one that must be reported then there will be a
13| return from the package by a 'jmp real_xxxx'. At that point
14| the machine state will be identical to the state before
15| the FPSP was entered. In particular, whatever condition
16| that caused the exception will still be pending when the FPSP
17| package returns. Thus, there will be system specific code
18| to handle the exception.
19|
20| If the exception was completely handled by the package, then
21| the return will be via a 'jmp fpsp_done'. Unless there is
22| OS specific work to be done (such as handling a context switch or
23| interrupt) the user program can be resumed via 'rte'.
24|
25| In the following skeleton code, some typical 'real_xxxx' handling
26| code is shown. This code may need to be moved to an appropriate
27| place in the target system, or rewritten.
28|
29
30| Copyright (C) Motorola, Inc. 1990
31| All Rights Reserved
32|
33| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
34| The copyright notice above does not evidence any
35| actual or intended publication of such source code.
36
37|
38| Modified for Linux-1.3.x by Jes Sorensen (jds@kom.auc.dk)
39|
40
41#include <linux/linkage.h>
42#include <asm/entry.h>
43#include <asm/offsets.h>
44
45|SKELETON idnt 2,1 | Motorola 040 Floating Point Software Package
46
47 |section 15
48|
49| The following counters are used for standalone testing
50|
51
52 |section 8
53
54#include "fpsp.h"
55
56 |xref b1238_fix
57
58|
59| Divide by Zero exception
60|
61| All dz exceptions are 'real', hence no fpsp_dz entry point.
62|
63 .global dz
64 .global real_dz
65dz:
66real_dz:
67 link %a6,#-LOCAL_SIZE
68 fsave -(%sp)
69 bclrb #E1,E_BYTE(%a6)
70 frestore (%sp)+
71 unlk %a6
72
73 SAVE_ALL_INT
74 GET_CURRENT(%d0)
75 movel %sp,%sp@- | stack frame pointer argument
76 bsrl trap_c
77 addql #4,%sp
78 bral ret_from_exception
79
80|
81| Inexact exception
82|
83| All inexact exceptions are real, but the 'real' handler
84| will probably want to clear the pending exception.
85| The provided code will clear the E3 exception (if pending),
86| otherwise clear the E1 exception. The frestore is not really
87| necessary for E1 exceptions.
88|
89| Code following the 'inex' label is to handle bug #1232. In this
90| bug, if an E1 snan, ovfl, or unfl occurred, and the process was
91| swapped out before taking the exception, the exception taken on
92| return was inex, rather than the correct exception. The snan, ovfl,
93| and unfl exception to be taken must not have been enabled. The
94| fix is to check for E1, and the existence of one of snan, ovfl,
95| or unfl bits set in the fpsr. If any of these are set, branch
96| to the appropriate handler for the exception in the fpsr. Note
97| that this fix is only for d43b parts, and is skipped if the
98| version number is not $40.
99|
100|
101 .global real_inex
102 .global inex
103inex:
104 link %a6,#-LOCAL_SIZE
105 fsave -(%sp)
106 cmpib #VER_40,(%sp) |test version number
107 bnes not_fmt40
108 fmovel %fpsr,-(%sp)
109 btstb #E1,E_BYTE(%a6) |test for E1 set
110 beqs not_b1232
111 btstb #snan_bit,2(%sp) |test for snan
112 beq inex_ckofl
113 addl #4,%sp
114 frestore (%sp)+
115 unlk %a6
116 bra snan
117inex_ckofl:
118 btstb #ovfl_bit,2(%sp) |test for ovfl
119 beq inex_ckufl
120 addl #4,%sp
121 frestore (%sp)+
122 unlk %a6
123 bra ovfl
124inex_ckufl:
125 btstb #unfl_bit,2(%sp) |test for unfl
126 beq not_b1232
127 addl #4,%sp
128 frestore (%sp)+
129 unlk %a6
130 bra unfl
131
132|
133| We do not have the bug 1232 case. Clean up the stack and call
134| real_inex.
135|
136not_b1232:
137 addl #4,%sp
138 frestore (%sp)+
139 unlk %a6
140
141real_inex:
142
143 link %a6,#-LOCAL_SIZE
144 fsave -(%sp)
145not_fmt40:
146 bclrb #E3,E_BYTE(%a6) |clear and test E3 flag
147 beqs inex_cke1
148|
149| Clear dirty bit on dest resister in the frame before branching
150| to b1238_fix.
151|
152 moveml %d0/%d1,USER_DA(%a6)
153 bfextu CMDREG1B(%a6){#6:#3},%d0 |get dest reg no
154 bclrb %d0,FPR_DIRTY_BITS(%a6) |clr dest dirty bit
155 bsrl b1238_fix |test for bug1238 case
156 moveml USER_DA(%a6),%d0/%d1
157 bras inex_done
158inex_cke1:
159 bclrb #E1,E_BYTE(%a6)
160inex_done:
161 frestore (%sp)+
162 unlk %a6
163
164 SAVE_ALL_INT
165 GET_CURRENT(%d0)
166 movel %sp,%sp@- | stack frame pointer argument
167 bsrl trap_c
168 addql #4,%sp
169 bral ret_from_exception
170
171|
172| Overflow exception
173|
174 |xref fpsp_ovfl
175 .global real_ovfl
176 .global ovfl
177ovfl:
178 jmp fpsp_ovfl
179real_ovfl:
180
181 link %a6,#-LOCAL_SIZE
182 fsave -(%sp)
183 bclrb #E3,E_BYTE(%a6) |clear and test E3 flag
184 bnes ovfl_done
185 bclrb #E1,E_BYTE(%a6)
186ovfl_done:
187 frestore (%sp)+
188 unlk %a6
189
190 SAVE_ALL_INT
191 GET_CURRENT(%d0)
192 movel %sp,%sp@- | stack frame pointer argument
193 bsrl trap_c
194 addql #4,%sp
195 bral ret_from_exception
196
197|
198| Underflow exception
199|
200 |xref fpsp_unfl
201 .global real_unfl
202 .global unfl
203unfl:
204 jmp fpsp_unfl
205real_unfl:
206
207 link %a6,#-LOCAL_SIZE
208 fsave -(%sp)
209 bclrb #E3,E_BYTE(%a6) |clear and test E3 flag
210 bnes unfl_done
211 bclrb #E1,E_BYTE(%a6)
212unfl_done:
213 frestore (%sp)+
214 unlk %a6
215
216 SAVE_ALL_INT
217 GET_CURRENT(%d0)
218 movel %sp,%sp@- | stack frame pointer argument
219 bsrl trap_c
220 addql #4,%sp
221 bral ret_from_exception
222
223|
224| Signalling NAN exception
225|
226 |xref fpsp_snan
227 .global real_snan
228 .global snan
229snan:
230 jmp fpsp_snan
231real_snan:
232 link %a6,#-LOCAL_SIZE
233 fsave -(%sp)
234 bclrb #E1,E_BYTE(%a6) |snan is always an E1 exception
235 frestore (%sp)+
236 unlk %a6
237
238 SAVE_ALL_INT
239 GET_CURRENT(%d0)
240 movel %sp,%sp@- | stack frame pointer argument
241 bsrl trap_c
242 addql #4,%sp
243 bral ret_from_exception
244
245|
246| Operand Error exception
247|
248 |xref fpsp_operr
249 .global real_operr
250 .global operr
251operr:
252 jmp fpsp_operr
253real_operr:
254 link %a6,#-LOCAL_SIZE
255 fsave -(%sp)
256 bclrb #E1,E_BYTE(%a6) |operr is always an E1 exception
257 frestore (%sp)+
258 unlk %a6
259
260 SAVE_ALL_INT
261 GET_CURRENT(%d0)
262 movel %sp,%sp@- | stack frame pointer argument
263 bsrl trap_c
264 addql #4,%sp
265 bral ret_from_exception
266
267
268|
269| BSUN exception
270|
271| This sample handler simply clears the nan bit in the FPSR.
272|
273 |xref fpsp_bsun
274 .global real_bsun
275 .global bsun
276bsun:
277 jmp fpsp_bsun
278real_bsun:
279 link %a6,#-LOCAL_SIZE
280 fsave -(%sp)
281 bclrb #E1,E_BYTE(%a6) |bsun is always an E1 exception
282 fmovel %FPSR,-(%sp)
283 bclrb #nan_bit,(%sp)
284 fmovel (%sp)+,%FPSR
285 frestore (%sp)+
286 unlk %a6
287
288 SAVE_ALL_INT
289 GET_CURRENT(%d0)
290 movel %sp,%sp@- | stack frame pointer argument
291 bsrl trap_c
292 addql #4,%sp
293 bral ret_from_exception
294
295|
296| F-line exception
297|
298| A 'real' F-line exception is one that the FPSP isn't supposed to
299| handle. E.g. an instruction with a co-processor ID that is not 1.
300|
301|
302 |xref fpsp_fline
303 .global real_fline
304 .global fline
305fline:
306 jmp fpsp_fline
307real_fline:
308
309 SAVE_ALL_INT
310 GET_CURRENT(%d0)
311 movel %sp,%sp@- | stack frame pointer argument
312 bsrl trap_c
313 addql #4,%sp
314 bral ret_from_exception
315
316|
317| Unsupported data type exception
318|
319 |xref fpsp_unsupp
320 .global real_unsupp
321 .global unsupp
322unsupp:
323 jmp fpsp_unsupp
324real_unsupp:
325 link %a6,#-LOCAL_SIZE
326 fsave -(%sp)
327 bclrb #E1,E_BYTE(%a6) |unsupp is always an E1 exception
328 frestore (%sp)+
329 unlk %a6
330
331 SAVE_ALL_INT
332 GET_CURRENT(%d0)
333 movel %sp,%sp@- | stack frame pointer argument
334 bsrl trap_c
335 addql #4,%sp
336 bral ret_from_exception
337
338|
339| Trace exception
340|
341 .global real_trace
342real_trace:
343 |
344 bral trap
345
346|
347| fpsp_fmt_error --- exit point for frame format error
348|
349| The fpu stack frame does not match the frames existing
350| or planned at the time of this writing. The fpsp is
351| unable to handle frame sizes not in the following
352| version:size pairs:
353|
354| {4060, 4160} - busy frame
355| {4028, 4130} - unimp frame
356| {4000, 4100} - idle frame
357|
358| This entry point simply holds an f-line illegal value.
359| Replace this with a call to your kernel panic code or
360| code to handle future revisions of the fpu.
361|
362 .global fpsp_fmt_error
363fpsp_fmt_error:
364
365 .long 0xf27f0000 |f-line illegal
366
367|
368| fpsp_done --- FPSP exit point
369|
370| The exception has been handled by the package and we are ready
371| to return to user mode, but there may be OS specific code
372| to execute before we do. If there is, do it now.
373|
374|
375
376 .global fpsp_done
377fpsp_done:
378 btst #0x5,%sp@ | supervisor bit set in saved SR?
379 beq .Lnotkern
380 rte
381.Lnotkern:
382 SAVE_ALL_INT
383 GET_CURRENT(%d0)
384 tstb %curptr@(TASK_NEEDRESCHED)
385 jne ret_from_exception | deliver signals,
386 | reschedule etc..
387 RESTORE_ALL
388
389|
390| mem_write --- write to user or supervisor address space
391|
392| Writes to memory while in supervisor mode. copyout accomplishes
393| this via a 'moves' instruction. copyout is a UNIX SVR3 (and later) function.
394| If you don't have copyout, use the local copy of the function below.
395|
396| a0 - supervisor source address
397| a1 - user destination address
398| d0 - number of bytes to write (maximum count is 12)
399|
400| The supervisor source address is guaranteed to point into the supervisor
401| stack. The result is that a UNIX
402| process is allowed to sleep as a consequence of a page fault during
403| copyout. The probability of a page fault is exceedingly small because
404| the 68040 always reads the destination address and thus the page
405| faults should have already been handled.
406|
407| If the EXC_SR shows that the exception was from supervisor space,
408| then just do a dumb (and slow) memory move. In a UNIX environment
409| there shouldn't be any supervisor mode floating point exceptions.
410|
411 .global mem_write
412mem_write:
413 btstb #5,EXC_SR(%a6) |check for supervisor state
414 beqs user_write
415super_write:
416 moveb (%a0)+,(%a1)+
417 subql #1,%d0
418 bnes super_write
419 rts
420user_write:
421 movel %d1,-(%sp) |preserve d1 just in case
422 movel %d0,-(%sp)
423 movel %a1,-(%sp)
424 movel %a0,-(%sp)
425 jsr copyout
426 addw #12,%sp
427 movel (%sp)+,%d1
428 rts
429|
430| mem_read --- read from user or supervisor address space
431|
432| Reads from memory while in supervisor mode. copyin accomplishes
433| this via a 'moves' instruction. copyin is a UNIX SVR3 (and later) function.
434| If you don't have copyin, use the local copy of the function below.
435|
436| The FPSP calls mem_read to read the original F-line instruction in order
437| to extract the data register number when the 'Dn' addressing mode is
438| used.
439|
440|Input:
441| a0 - user source address
442| a1 - supervisor destination address
443| d0 - number of bytes to read (maximum count is 12)
444|
445| Like mem_write, mem_read always reads with a supervisor
446| destination address on the supervisor stack. Also like mem_write,
447| the EXC_SR is checked and a simple memory copy is done if reading
448| from supervisor space is indicated.
449|
450 .global mem_read
451mem_read:
452 btstb #5,EXC_SR(%a6) |check for supervisor state
453 beqs user_read
454super_read:
455 moveb (%a0)+,(%a1)+
456 subql #1,%d0
457 bnes super_read
458 rts
459user_read:
460 movel %d1,-(%sp) |preserve d1 just in case
461 movel %d0,-(%sp)
462 movel %a1,-(%sp)
463 movel %a0,-(%sp)
464 jsr copyin
465 addw #12,%sp
466 movel (%sp)+,%d1
467 rts
468
469|
470| Use these routines if your kernel doesn't have copyout/copyin equivalents.
471| Assumes that D0/D1/A0/A1 are scratch registers. copyout overwrites DFC,
472| and copyin overwrites SFC.
473|
474copyout:
475 movel 4(%sp),%a0 | source
476 movel 8(%sp),%a1 | destination
477 movel 12(%sp),%d0 | count
478 subl #1,%d0 | dec count by 1 for dbra
479 movel #1,%d1
480
481| DFC is already set
482| movec %d1,%DFC | set dfc for user data space
483moreout:
484 moveb (%a0)+,%d1 | fetch supervisor byte
485out_ea:
486 movesb %d1,(%a1)+ | write user byte
487 dbf %d0,moreout
488 rts
489
490copyin:
491 movel 4(%sp),%a0 | source
492 movel 8(%sp),%a1 | destination
493 movel 12(%sp),%d0 | count
494 subl #1,%d0 | dec count by 1 for dbra
495 movel #1,%d1
496| SFC is already set
497| movec %d1,%SFC | set sfc for user space
498morein:
499in_ea:
500 movesb (%a0)+,%d1 | fetch user byte
501 moveb %d1,(%a1)+ | write supervisor byte
502 dbf %d0,morein
503 rts
504
505 .section .fixup,#alloc,#execinstr
506 .even
5071:
508 jbra fpsp040_die
509
510 .section __ex_table,#alloc
511 .align 4
512
513 .long in_ea,1b
514 .long out_ea,1b
515
516 |end
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