|
| 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
|
| For details on the license for this file, please see the
| file, README, in this same directory.
|
| Modified for Linux-1.3.x by Jes Sorensen (jds@kom.auc.dk)
|
#include <linux/linkage.h>
#include <asm/entry.h>
#include <asm/asm-offsets.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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral 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 trap_c
addql #4,%sp
bral ret_from_exception
|
| Trace exception
|
.global real_trace
real_trace:
|
bral 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)
| deliver signals, reschedule etc..
jra ret_from_exception
|
| 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,"ax"
.even
1:
jbsr fpsp040_die
jbra .Lnotkern
.section __ex_table,"a"
.align 4
.long in_ea,1b
.long out_ea,1b
|end