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+|
+| 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