Annotation of sys/arch/m68k/fpsp/netbsd.sa, Revision 1.1.1.1
1.1 nbrk 1: * $OpenBSD: netbsd.sa,v 1.5 2004/01/27 16:16:27 miod Exp $
2: * $NetBSD: netbsd.sa,v 1.3 1997/04/25 02:26:04 thorpej Exp $
3:
4: * MOTOROLA MICROPROCESSOR & MEMORY TECHNOLOGY GROUP
5: * M68000 Hi-Performance Microprocessor Division
6: * M68040 Software Package
7: *
8: * M68040 Software Package Copyright (c) 1993, 1994 Motorola Inc.
9: * All rights reserved.
10: *
11: * THE SOFTWARE is provided on an "AS IS" basis and without warranty.
12: * To the maximum extent permitted by applicable law,
13: * MOTOROLA DISCLAIMS ALL WARRANTIES WHETHER EXPRESS OR IMPLIED,
14: * INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
15: * PARTICULAR PURPOSE and any warranty against infringement with
16: * regard to the SOFTWARE (INCLUDING ANY MODIFIED VERSIONS THEREOF)
17: * and any accompanying written materials.
18: *
19: * To the maximum extent permitted by applicable law,
20: * IN NO EVENT SHALL MOTOROLA BE LIABLE FOR ANY DAMAGES WHATSOEVER
21: * (INCLUDING WITHOUT LIMITATION, DAMAGES FOR LOSS OF BUSINESS
22: * PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, OR
23: * OTHER PECUNIARY LOSS) ARISING OF THE USE OR INABILITY TO USE THE
24: * SOFTWARE. Motorola assumes no responsibility for the maintenance
25: * and support of the SOFTWARE.
26: *
27: * You are hereby granted a copyright license to use, modify, and
28: * distribute the SOFTWARE so long as this entire notice is retained
29: * without alteration in any modified and/or redistributed versions,
30: * and that such modified versions are clearly identified as such.
31: * No licenses are granted by implication, estoppel or otherwise
32: * under any patents or trademarks of Motorola, Inc.
33:
34: *
35: * skeleton.sa 3.2 4/26/91
36: *
37: * This file contains code that is system dependent and will
38: * need to be modified to install the FPSP.
39: *
40: * Each entry point for exception 'xxxx' begins with a 'jmp fpsp_xxxx'.
41: * Put any target system specific handling that must be done immediately
42: * before the jump instruction. If there no handling necessary, then
43: * the 'fpsp_xxxx' handler entry point should be placed in the exception
44: * table so that the 'jmp' can be eliminated. If the FPSP determines that the
45: * exception is one that must be reported then there will be a
46: * return from the package by a 'jmp real_xxxx'. At that point
47: * the machine state will be identical to the state before
48: * the FPSP was entered. In particular, whatever condition
49: * that caused the exception will still be pending when the FPSP
50: * package returns. Thus, there will be system specific code
51: * to handle the exception.
52: *
53: * If the exception was completely handled by the package, then
54: * the return will be via a 'jmp fpsp_done'. Unless there is
55: * OS specific work to be done (such as handling a context switch or
56: * interrupt) the user program can be resumed via 'rte'.
57: *
58: * In the following skeleton code, some typical 'real_xxxx' handling
59: * code is shown. This code may need to be moved to an appropriate
60: * place in the target system, or rewritten.
61: *
62:
63: SKELETON IDNT 2,1 Motorola 040 Floating Point Software Package
64:
65: section 15
66: *
67: * The following counters are used for standalone testing
68: *
69:
70: section 8
71:
72: include fpsp.h
73:
74: *
75: * XXX Note, this is NOT valid Motorola syntax, but what else can we do?
76: *
77: #include "../include/asm.h"
78:
79: xref b1238_fix
80:
81: *
82: * Divide by Zero exception
83: *
84: * All dz exceptions are 'real', hence no fpsp_dz entry point.
85: *
86: xdef dz
87: dz:
88: link a6,#-LOCAL_SIZE
89: fsave -(sp)
90: bclr.b #E1,E_BYTE(a6)
91: frestore (sp)+
92: unlk a6
93: jmp _C_LABEL(fpfault)
94:
95: *
96: * Inexact exception
97: *
98: * All inexact exceptions are real, but the 'real' handler
99: * will probably want to clear the pending exception.
100: * The provided code will clear the E3 exception (if pending),
101: * otherwise clear the E1 exception. The frestore is not really
102: * necessary for E1 exceptions.
103: *
104: * Code following the 'inex' label is to handle bug #1232. In this
105: * bug, if an E1 snan, ovfl, or unfl occurred, and the process was
106: * swapped out before taking the exception, the exception taken on
107: * return was inex, rather than the correct exception. The snan, ovfl,
108: * and unfl exception to be taken must not have been enabled. The
109: * fix is to check for E1, and the existence of one of snan, ovfl,
110: * or unfl bits set in the fpsr. If any of these are set, branch
111: * to the appropriate handler for the exception in the fpsr. Note
112: * that this fix is only for d43b parts, and is skipped if the
113: * version number is not $40.
114: *
115: *
116: xdef real_inex
117: xdef inex
118: inex:
119: link a6,#-LOCAL_SIZE
120: fsave -(sp)
121: cmpi.b #VER_40,(sp) ;test version number
122: bne.b not_fmt40
123: fmove.l fpsr,-(sp)
124: btst.b #E1,E_BYTE(a6) ;test for E1 set
125: beq.b not_b1232
126: btst.b #snan_bit,2(sp) ;test for snan
127: beq inex_ckofl
128: addq.l #4,sp
129: frestore (sp)+
130: unlk a6
131: bra fpsp_snan
132: inex_ckofl:
133: btst.b #ovfl_bit,2(sp) ;test for ovfl
134: beq inex_ckufl
135: addq.l #4,sp
136: frestore (sp)+
137: unlk a6
138: bra fpsp_ovfl
139: inex_ckufl:
140: btst.b #unfl_bit,2(sp) ;test for unfl
141: beq not_b1232
142: addq.l #4,sp
143: frestore (sp)+
144: unlk a6
145: bra fpsp_unfl
146:
147: *
148: * We do not have the bug 1232 case. Clean up the stack and call
149: * real_inex.
150: *
151: not_b1232:
152: addq.l #4,sp
153: frestore (sp)+
154: unlk a6
155:
156: real_inex:
157: link a6,#-LOCAL_SIZE
158: fsave -(sp)
159: not_fmt40:
160: bclr.b #E3,E_BYTE(a6) ;clear and test E3 flag
161: beq.b inex_cke1
162: *
163: * Clear dirty bit on dest resister in the frame before branching
164: * to b1238_fix.
165: *
166: movem.l d0/d1,USER_DA(a6)
167: bfextu CMDREG1B(a6){6:3},d0 ;get dest reg no
168: bclr.b d0,FPR_DIRTY_BITS(a6) ;clr dest dirty bit
169: bsr.l b1238_fix ;test for bug1238 case
170: movem.l USER_DA(a6),d0/d1
171: bra.b inex_done
172: inex_cke1:
173: bclr.b #E1,E_BYTE(a6)
174: inex_done:
175: frestore (sp)+
176: unlk a6
177: jmp _C_LABEL(fpfault)
178:
179: *
180: * Overflow exception
181: *
182: xdef real_ovfl
183: real_ovfl:
184: link a6,#-LOCAL_SIZE
185: fsave -(sp)
186: bclr.b #E3,E_BYTE(a6) ;clear and test E3 flag
187: bne.b ovfl_done
188: bclr.b #E1,E_BYTE(a6)
189: ovfl_done:
190: frestore (sp)+
191: unlk a6
192: jmp _C_LABEL(fpfault)
193:
194: *
195: * Underflow exception
196: *
197: xdef real_unfl
198: real_unfl:
199: link a6,#-LOCAL_SIZE
200: fsave -(sp)
201: bclr.b #E3,E_BYTE(a6) ;clear and test E3 flag
202: bne.b unfl_done
203: bclr.b #E1,E_BYTE(a6)
204: unfl_done:
205: frestore (sp)+
206: unlk a6
207: jmp _C_LABEL(fpfault)
208:
209: *
210: * Signalling NAN exception
211: *
212: xdef real_snan
213: real_snan:
214: link a6,#-LOCAL_SIZE
215: fsave -(sp)
216: bclr.b #E1,E_BYTE(a6) ;snan is always an E1 exception
217: frestore (sp)+
218: unlk a6
219: jmp _C_LABEL(fpfault)
220:
221: *
222: * Operand Error exception
223: *
224: xdef real_operr
225: real_operr:
226: link a6,#-LOCAL_SIZE
227: fsave -(sp)
228: bclr.b #E1,E_BYTE(a6) ;operr is always an E1 exception
229: frestore (sp)+
230: unlk a6
231: jmp _C_LABEL(fpfault)
232:
233: *
234: * BSUN exception
235: *
236: * This sample handler simply clears the nan bit in the FPSR.
237: *
238: xdef real_bsun
239: real_bsun:
240: link a6,#-LOCAL_SIZE
241: fsave -(sp)
242: bclr.b #E1,E_BYTE(a6) ;bsun is always an E1 exception
243: fmove.l FPSR,-(sp)
244: bclr.b #nan_bit,(sp)
245: fmove.l (sp)+,FPSR
246: frestore (sp)+
247: unlk a6
248: jmp _C_LABEL(fpfault)
249:
250: *
251: * F-line exception
252: *
253: * A 'real' F-line exception is one that the FPSP isn't supposed to
254: * handle. E.g. an instruction with a co-processor ID that is not 1.
255: *
256: *
257: xdef real_fline
258: real_fline:
259: jmp _C_LABEL(fpfault)
260:
261: *
262: * Unsupported data type exception
263: *
264: xdef real_unsupp
265: real_unsupp:
266: link a6,#-LOCAL_SIZE
267: fsave -(sp)
268: bclr.b #E1,E_BYTE(a6) ;unsupp is always an E1 exception
269: frestore (sp)+
270: unlk a6
271: jmp _C_LABEL(fpfault)
272:
273: *
274: * Trace exception
275: *
276: xdef real_trace
277: real_trace:
278: rte
279:
280: *
281: * fpsp_fmt_error --- exit point for frame format error
282: *
283: * The fpu stack frame does not match the frames existing
284: * or planned at the time of this writing. The fpsp is
285: * unable to handle frame sizes not in the following
286: * version:size pairs:
287: *
288: * {4060, 4160} - busy frame
289: * {4028, 4130} - unimp frame
290: * {4000, 4100} - idle frame
291: *
292: * This entry point simply holds an f-line illegal value.
293: * Replace this with a call to your kernel panic code or
294: * code to handle future revisions of the fpu.
295: *
296: xdef fpsp_fmt_error
297: fpsp_fmt_error:
298: pea 1f
299: jsr _C_LABEL(panic)
300: dc.l $f27f0000 ;f-line illegal
301: 1:
302: .asciz "bad floating point stack frame"
303: .even
304:
305: *
306: * fpsp_done --- FPSP exit point
307: *
308: * The exception has been handled by the package and we are ready
309: * to return to user mode, but there may be OS specific code
310: * to execute before we do. If there is, do it now.
311: *
312: *
313: xref _ASM_LABEL(rei)
314: xdef fpsp_done
315: fpsp_done:
316: jmp _ASM_LABEL(rei)
317:
318: *
319: * mem_write --- write to user or supervisor address space
320: *
321: * Writes to memory while in supervisor mode. copyout accomplishes
322: * this via a 'moves' instruction. copyout is a UNIX SVR3 (and later) function.
323: * If you don't have copyout, use the local copy of the function below.
324: *
325: * a0 - supervisor source address
326: * a1 - user destination address
327: * d0 - number of bytes to write (maximum count is 12)
328: *
329: * The supervisor source address is guaranteed to point into the supervisor
330: * stack. The result is that a UNIX
331: * process is allowed to sleep as a consequence of a page fault during
332: * copyout. The probability of a page fault is exceedingly small because
333: * the 68040 always reads the destination address and thus the page
334: * faults should have already been handled.
335: *
336: * If the EXC_SR shows that the exception was from supervisor space,
337: * then just do a dumb (and slow) memory move. In a UNIX environment
338: * there shouldn't be any supervisor mode floating point exceptions.
339: *
340: xdef mem_write
341: mem_write:
342: btst.b #5,EXC_SR(a6) ;check for supervisor state
343: beq.b user_write
344: super_write:
345: move.b (a0)+,(a1)+
346: subq.l #1,d0
347: bne.b super_write
348: rts
349: user_write:
350: move.l d1,-(sp) ;preserve d1 just in case
351: move.l d0,-(sp)
352: move.l a1,-(sp)
353: move.l a0,-(sp)
354: jsr _C_LABEL(copyout)
355: add.l #12,sp
356: move.l (sp)+,d1
357: rts
358:
359: *
360: * mem_read --- read from user or supervisor address space
361: *
362: * Reads from memory while in supervisor mode. copyin accomplishes
363: * this via a 'moves' instruction. copyin is a UNIX SVR3 (and later) function.
364: * If you don't have copyin, use the local copy of the function below.
365: *
366: * The FPSP calls mem_read to read the original F-line instruction in order
367: * to extract the data register number when the 'Dn' addressing mode is
368: * used.
369: *
370: *Input:
371: * a0 - user source address
372: * a1 - supervisor destination address
373: * d0 - number of bytes to read (maximum count is 12)
374: *
375: * Like mem_write, mem_read always reads with a supervisor
376: * destination address on the supervisor stack. Also like mem_write,
377: * the EXC_SR is checked and a simple memory copy is done if reading
378: * from supervisor space is indicated.
379: *
380: xdef mem_read
381: mem_read:
382: btst.b #5,EXC_SR(a6) ;check for supervisor state
383: beq.b user_read
384: super_read:
385: move.b (a0)+,(a1)+
386: subq.l #1,d0
387: bne.b super_read
388: rts
389: user_read:
390: move.l d1,-(sp) ;preserve d1 just in case
391: move.l d0,-(sp)
392: move.l a1,-(sp)
393: move.l a0,-(sp)
394: jsr _C_LABEL(copyin)
395: add.l #12,sp
396: move.l (sp)+,d1
397: rts
398:
399: end
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