2 | skeleton.sa 3.2 4/26/91
4 | This file contains code that is system dependent and will
5 | need to be modified to install the FPSP.
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.
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'.
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.
30 | Copyright (C) Motorola, Inc. 1990
33 | THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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.
38 | Modified for Linux-1.3.x by Jes Sorensen (jds@kom.auc.dk)
41 #include <linux/linkage.h>
42 #include <asm/entry.h>
43 #include <asm/offsets.h>
45 |SKELETON idnt 2,1 | Motorola 040 Floating Point Software Package
49 | The following counters are used for standalone testing
59 | Divide by Zero exception
61 | All dz exceptions are 'real', hence no fpsp_dz entry point.
75 movel %sp,%sp@- | stack frame pointer argument
78 bral ret_from_exception
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.
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.
104 link %a6,#-LOCAL_SIZE
106 cmpib #VER_40,(%sp) |test version number
109 btstb #E1,E_BYTE(%a6) |test for E1 set
111 btstb #snan_bit,2(%sp) |test for snan
118 btstb #ovfl_bit,2(%sp) |test for ovfl
125 btstb #unfl_bit,2(%sp) |test for unfl
133 | We do not have the bug 1232 case. Clean up the stack and call
143 link %a6,#-LOCAL_SIZE
146 bclrb #E3,E_BYTE(%a6) |clear and test E3 flag
149 | Clear dirty bit on dest resister in the frame before branching
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
159 bclrb #E1,E_BYTE(%a6)
166 movel %sp,%sp@- | stack frame pointer argument
169 bral ret_from_exception
181 link %a6,#-LOCAL_SIZE
183 bclrb #E3,E_BYTE(%a6) |clear and test E3 flag
185 bclrb #E1,E_BYTE(%a6)
192 movel %sp,%sp@- | stack frame pointer argument
195 bral ret_from_exception
198 | Underflow exception
207 link %a6,#-LOCAL_SIZE
209 bclrb #E3,E_BYTE(%a6) |clear and test E3 flag
211 bclrb #E1,E_BYTE(%a6)
218 movel %sp,%sp@- | stack frame pointer argument
221 bral ret_from_exception
224 | Signalling NAN exception
232 link %a6,#-LOCAL_SIZE
234 bclrb #E1,E_BYTE(%a6) |snan is always an E1 exception
240 movel %sp,%sp@- | stack frame pointer argument
243 bral ret_from_exception
246 | Operand Error exception
254 link %a6,#-LOCAL_SIZE
256 bclrb #E1,E_BYTE(%a6) |operr is always an E1 exception
262 movel %sp,%sp@- | stack frame pointer argument
265 bral ret_from_exception
271 | This sample handler simply clears the nan bit in the FPSR.
279 link %a6,#-LOCAL_SIZE
281 bclrb #E1,E_BYTE(%a6) |bsun is always an E1 exception
290 movel %sp,%sp@- | stack frame pointer argument
293 bral ret_from_exception
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.
311 movel %sp,%sp@- | stack frame pointer argument
314 bral ret_from_exception
317 | Unsupported data type exception
325 link %a6,#-LOCAL_SIZE
327 bclrb #E1,E_BYTE(%a6) |unsupp is always an E1 exception
333 movel %sp,%sp@- | stack frame pointer argument
336 bral ret_from_exception
347 | fpsp_fmt_error --- exit point for frame format error
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:
354 | {4060, 4160} - busy frame
355 | {4028, 4130} - unimp frame
356 | {4000, 4100} - idle frame
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.
362 .global fpsp_fmt_error
365 .long 0xf27f0000 |f-line illegal
368 | fpsp_done --- FPSP exit point
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.
378 btst #0x5,%sp@ | supervisor bit set in saved SR?
384 tstb %curptr@(TASK_NEEDRESCHED)
385 jne ret_from_exception | deliver signals,
390 | mem_write --- write to user or supervisor address space
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.
396 | a0 - supervisor source address
397 | a1 - user destination address
398 | d0 - number of bytes to write (maximum count is 12)
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.
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.
413 btstb #5,EXC_SR(%a6) |check for supervisor state
421 movel %d1,-(%sp) |preserve d1 just in case
430 | mem_read --- read from user or supervisor address space
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.
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
441 | a0 - user source address
442 | a1 - supervisor destination address
443 | d0 - number of bytes to read (maximum count is 12)
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.
452 btstb #5,EXC_SR(%a6) |check for supervisor state
460 movel %d1,-(%sp) |preserve d1 just in case
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.
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
482 | movec %d1,%DFC | set dfc for user data space
484 moveb (%a0)+,%d1 | fetch supervisor byte
486 movesb %d1,(%a1)+ | write user byte
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
497 | movec %d1,%SFC | set sfc for user space
500 movesb (%a0)+,%d1 | fetch user byte
501 moveb %d1,(%a1)+ | write supervisor byte
505 .section .fixup,#alloc,#execinstr
510 .section __ex_table,#alloc