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linuxdebug/arch/m68k/fpsp040/bugfix.S

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null pointer error
2024-07-16 15:50:57 +02:00
|
| bugfix.sa 3.2 1/31/91
|
|
| This file contains workarounds for bugs in the 040
| relating to the Floating-Point Software Package (FPSP)
|
| Fixes for bugs: 1238
|
| Bug: 1238
|
|
| /* The following dirty_bit clear should be left in
| * the handler permanently to improve throughput.
| * The dirty_bits are located at bits [23:16] in
| * longword $08 in the busy frame $4x60. Bit 16
| * corresponds to FP0, bit 17 corresponds to FP1,
| * and so on.
| */
| if (E3_exception_just_serviced) {
| dirty_bit[cmdreg3b[9:7]] = 0;
| }
|
| if (fsave_format_version != $40) {goto NOFIX}
|
| if !(E3_exception_just_serviced) {goto NOFIX}
| if (cupc == 0000000) {goto NOFIX}
| if ((cmdreg1b[15:13] != 000) &&
| (cmdreg1b[15:10] != 010001)) {goto NOFIX}
| if (((cmdreg1b[15:13] != 000) || ((cmdreg1b[12:10] != cmdreg2b[9:7]) &&
| (cmdreg1b[12:10] != cmdreg3b[9:7])) ) &&
| ((cmdreg1b[ 9: 7] != cmdreg2b[9:7]) &&
| (cmdreg1b[ 9: 7] != cmdreg3b[9:7])) ) {goto NOFIX}
|
| /* Note: for 6d43b or 8d43b, you may want to add the following code
| * to get better coverage. (If you do not insert this code, the part
| * won't lock up; it will simply get the wrong answer.)
| * Do NOT insert this code for 10d43b or later parts.
| *
| * if (fpiarcu == integer stack return address) {
| * cupc = 0000000;
| * goto NOFIX;
| * }
| */
|
| if (cmdreg1b[15:13] != 000) {goto FIX_OPCLASS2}
| FIX_OPCLASS0:
| if (((cmdreg1b[12:10] == cmdreg2b[9:7]) ||
| (cmdreg1b[ 9: 7] == cmdreg2b[9:7])) &&
| (cmdreg1b[12:10] != cmdreg3b[9:7]) &&
| (cmdreg1b[ 9: 7] != cmdreg3b[9:7])) { /* xu conflict only */
| /* We execute the following code if there is an
| xu conflict and NOT an nu conflict */
|
| /* first save some values on the fsave frame */
| stag_temp = STAG[fsave_frame];
| cmdreg1b_temp = CMDREG1B[fsave_frame];
| dtag_temp = DTAG[fsave_frame];
| ete15_temp = ETE15[fsave_frame];
|
| CUPC[fsave_frame] = 0000000;
| FRESTORE
| FSAVE
|
| /* If the xu instruction is exceptional, we punt.
| * Otherwise, we would have to include OVFL/UNFL handler
| * code here to get the correct answer.
| */
| if (fsave_frame_format == $4060) {goto KILL_PROCESS}
|
| fsave_frame = /* build a long frame of all zeros */
| fsave_frame_format = $4060; /* label it as long frame */
|
| /* load it with the temps we saved */
| STAG[fsave_frame] = stag_temp;
| CMDREG1B[fsave_frame] = cmdreg1b_temp;
| DTAG[fsave_frame] = dtag_temp;
| ETE15[fsave_frame] = ete15_temp;
|
| /* Make sure that the cmdreg3b dest reg is not going to
| * be destroyed by a FMOVEM at the end of all this code.
| * If it is, you should move the current value of the reg
| * onto the stack so that the reg will loaded with that value.
| */
|
| /* All done. Proceed with the code below */
| }
|
| etemp = FP_reg_[cmdreg1b[12:10]];
| ete15 = ~ete14;
| cmdreg1b[15:10] = 010010;
| clear(bug_flag_procIDxxxx);
| FRESTORE and return;
|
|
| FIX_OPCLASS2:
| if ((cmdreg1b[9:7] == cmdreg2b[9:7]) &&
| (cmdreg1b[9:7] != cmdreg3b[9:7])) { /* xu conflict only */
| /* We execute the following code if there is an
| xu conflict and NOT an nu conflict */
|
| /* first save some values on the fsave frame */
| stag_temp = STAG[fsave_frame];
| cmdreg1b_temp = CMDREG1B[fsave_frame];
| dtag_temp = DTAG[fsave_frame];
| ete15_temp = ETE15[fsave_frame];
| etemp_temp = ETEMP[fsave_frame];
|
| CUPC[fsave_frame] = 0000000;
| FRESTORE
| FSAVE
|
|
| /* If the xu instruction is exceptional, we punt.
| * Otherwise, we would have to include OVFL/UNFL handler
| * code here to get the correct answer.
| */
| if (fsave_frame_format == $4060) {goto KILL_PROCESS}
|
| fsave_frame = /* build a long frame of all zeros */
| fsave_frame_format = $4060; /* label it as long frame */
|
| /* load it with the temps we saved */
| STAG[fsave_frame] = stag_temp;
| CMDREG1B[fsave_frame] = cmdreg1b_temp;
| DTAG[fsave_frame] = dtag_temp;
| ETE15[fsave_frame] = ete15_temp;
| ETEMP[fsave_frame] = etemp_temp;
|
| /* Make sure that the cmdreg3b dest reg is not going to
| * be destroyed by a FMOVEM at the end of all this code.
| * If it is, you should move the current value of the reg
| * onto the stack so that the reg will loaded with that value.
| */
|
| /* All done. Proceed with the code below */
| }
|
| if (etemp_exponent == min_sgl) etemp_exponent = min_dbl;
| if (etemp_exponent == max_sgl) etemp_exponent = max_dbl;
| cmdreg1b[15:10] = 010101;
| clear(bug_flag_procIDxxxx);
| FRESTORE and return;
|
|
| NOFIX:
| clear(bug_flag_procIDxxxx);
| FRESTORE and return;
|
| 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.
|BUGFIX idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
#include "fpsp.h"
|xref fpsp_fmt_error
.global b1238_fix
b1238_fix:
|
| This code is entered only on completion of the handling of an
| nu-generated ovfl, unfl, or inex exception. If the version
| number of the fsave is not $40, this handler is not necessary.
| Simply branch to fix_done and exit normally.
|
cmpib #VER_40,4(%a7)
bne fix_done
|
| Test for cu_savepc equal to zero. If not, this is not a bug
| #1238 case.
|
moveb CU_SAVEPC(%a6),%d0
andib #0xFE,%d0
beq fix_done |if zero, this is not bug #1238
|
| Test the register conflict aspect. If opclass0, check for
| cu src equal to xu dest or equal to nu dest. If so, go to
| op0. Else, or if opclass2, check for cu dest equal to
| xu dest or equal to nu dest. If so, go to tst_opcl. Else,
| exit, it is not the bug case.
|
| Check for opclass 0. If not, go and check for opclass 2 and sgl.
|
movew CMDREG1B(%a6),%d0
andiw #0xE000,%d0 |strip all but opclass
bne op2sgl |not opclass 0, check op2
|
| Check for cu and nu register conflict. If one exists, this takes
| priority over a cu and xu conflict.
|
bfextu CMDREG1B(%a6){#3:#3},%d0 |get 1st src
bfextu CMDREG3B(%a6){#6:#3},%d1 |get 3rd dest
cmpb %d0,%d1
beqs op0 |if equal, continue bugfix
|
| Check for cu dest equal to nu dest. If so, go and fix the
| bug condition. Otherwise, exit.
|
bfextu CMDREG1B(%a6){#6:#3},%d0 |get 1st dest
cmpb %d0,%d1 |cmp 1st dest with 3rd dest
beqs op0 |if equal, continue bugfix
|
| Check for cu and xu register conflict.
|
bfextu CMDREG2B(%a6){#6:#3},%d1 |get 2nd dest
cmpb %d0,%d1 |cmp 1st dest with 2nd dest
beqs op0_xu |if equal, continue bugfix
bfextu CMDREG1B(%a6){#3:#3},%d0 |get 1st src
cmpb %d0,%d1 |cmp 1st src with 2nd dest
beq op0_xu
bne fix_done |if the reg checks fail, exit
|
| We have the opclass 0 situation.
|
op0:
bfextu CMDREG1B(%a6){#3:#3},%d0 |get source register no
movel #7,%d1
subl %d0,%d1
clrl %d0
bsetl %d1,%d0
fmovemx %d0,ETEMP(%a6) |load source to ETEMP
moveb #0x12,%d0
bfins %d0,CMDREG1B(%a6){#0:#6} |opclass 2, extended
|
| Set ETEMP exponent bit 15 as the opposite of ete14
|
btst #6,ETEMP_EX(%a6) |check etemp exponent bit 14
beq setete15
bclr #etemp15_bit,STAG(%a6)
bra finish
setete15:
bset #etemp15_bit,STAG(%a6)
bra finish
|
| We have the case in which a conflict exists between the cu src or
| dest and the dest of the xu. We must clear the instruction in
| the cu and restore the state, allowing the instruction in the
| xu to complete. Remember, the instruction in the nu
| was exceptional, and was completed by the appropriate handler.
| If the result of the xu instruction is not exceptional, we can
| restore the instruction from the cu to the frame and continue
| processing the original exception. If the result is also
| exceptional, we choose to kill the process.
|
| Items saved from the stack:
|
| $3c stag - L_SCR1
| $40 cmdreg1b - L_SCR2
| $44 dtag - L_SCR3
|
| The cu savepc is set to zero, and the frame is restored to the
| fpu.
|
op0_xu:
movel STAG(%a6),L_SCR1(%a6)
movel CMDREG1B(%a6),L_SCR2(%a6)
movel DTAG(%a6),L_SCR3(%a6)
andil #0xe0000000,L_SCR3(%a6)
moveb #0,CU_SAVEPC(%a6)
movel (%a7)+,%d1 |save return address from bsr
frestore (%a7)+
fsave -(%a7)
|
| Check if the instruction which just completed was exceptional.
|
cmpw #0x4060,(%a7)
beq op0_xb
|
| It is necessary to isolate the result of the instruction in the
| xu if it is to fp0 - fp3 and write that value to the USER_FPn
| locations on the stack. The correct destination register is in
| cmdreg2b.
|
bfextu CMDREG2B(%a6){#6:#3},%d0 |get dest register no
cmpil #3,%d0
bgts op0_xi
beqs op0_fp3
cmpil #1,%d0
blts op0_fp0
beqs op0_fp1
op0_fp2:
fmovemx %fp2-%fp2,USER_FP2(%a6)
bras op0_xi
op0_fp1:
fmovemx %fp1-%fp1,USER_FP1(%a6)
bras op0_xi
op0_fp0:
fmovemx %fp0-%fp0,USER_FP0(%a6)
bras op0_xi
op0_fp3:
fmovemx %fp3-%fp3,USER_FP3(%a6)
|
| The frame returned is idle. We must build a busy frame to hold
| the cu state information and setup etemp.
|
op0_xi:
movel #22,%d0 |clear 23 lwords
clrl (%a7)
op0_loop:
clrl -(%a7)
dbf %d0,op0_loop
movel #0x40600000,-(%a7)
movel L_SCR1(%a6),STAG(%a6)
movel L_SCR2(%a6),CMDREG1B(%a6)
movel L_SCR3(%a6),DTAG(%a6)
moveb #0x6,CU_SAVEPC(%a6)
movel %d1,-(%a7) |return bsr return address
bfextu CMDREG1B(%a6){#3:#3},%d0 |get source register no
movel #7,%d1
subl %d0,%d1
clrl %d0
bsetl %d1,%d0
fmovemx %d0,ETEMP(%a6) |load source to ETEMP
moveb #0x12,%d0
bfins %d0,CMDREG1B(%a6){#0:#6} |opclass 2, extended
|
| Set ETEMP exponent bit 15 as the opposite of ete14
|
btst #6,ETEMP_EX(%a6) |check etemp exponent bit 14
beq op0_sete15
bclr #etemp15_bit,STAG(%a6)
bra finish
op0_sete15:
bset #etemp15_bit,STAG(%a6)
bra finish
|
| The frame returned is busy. It is not possible to reconstruct
| the code sequence to allow completion. We will jump to
| fpsp_fmt_error and allow the kernel to kill the process.
|
op0_xb:
jmp fpsp_fmt_error
|
| Check for opclass 2 and single size. If not both, exit.
|
op2sgl:
movew CMDREG1B(%a6),%d0
andiw #0xFC00,%d0 |strip all but opclass and size
cmpiw #0x4400,%d0 |test for opclass 2 and size=sgl
bne fix_done |if not, it is not bug 1238
|
| Check for cu dest equal to nu dest or equal to xu dest, with
| a cu and nu conflict taking priority an nu conflict. If either,
| go and fix the bug condition. Otherwise, exit.
|
bfextu CMDREG1B(%a6){#6:#3},%d0 |get 1st dest
bfextu CMDREG3B(%a6){#6:#3},%d1 |get 3rd dest
cmpb %d0,%d1 |cmp 1st dest with 3rd dest
beq op2_com |if equal, continue bugfix
bfextu CMDREG2B(%a6){#6:#3},%d1 |get 2nd dest
cmpb %d0,%d1 |cmp 1st dest with 2nd dest
bne fix_done |if the reg checks fail, exit
|
| We have the case in which a conflict exists between the cu src or
| dest and the dest of the xu. We must clear the instruction in
| the cu and restore the state, allowing the instruction in the
| xu to complete. Remember, the instruction in the nu
| was exceptional, and was completed by the appropriate handler.
| If the result of the xu instruction is not exceptional, we can
| restore the instruction from the cu to the frame and continue
| processing the original exception. If the result is also
| exceptional, we choose to kill the process.
|
| Items saved from the stack:
|
| $3c stag - L_SCR1
| $40 cmdreg1b - L_SCR2
| $44 dtag - L_SCR3
| etemp - FP_SCR2
|
| The cu savepc is set to zero, and the frame is restored to the
| fpu.
|
op2_xu:
movel STAG(%a6),L_SCR1(%a6)
movel CMDREG1B(%a6),L_SCR2(%a6)
movel DTAG(%a6),L_SCR3(%a6)
andil #0xe0000000,L_SCR3(%a6)
moveb #0,CU_SAVEPC(%a6)
movel ETEMP(%a6),FP_SCR2(%a6)
movel ETEMP_HI(%a6),FP_SCR2+4(%a6)
movel ETEMP_LO(%a6),FP_SCR2+8(%a6)
movel (%a7)+,%d1 |save return address from bsr
frestore (%a7)+
fsave -(%a7)
|
| Check if the instruction which just completed was exceptional.
|
cmpw #0x4060,(%a7)
beq op2_xb
|
| It is necessary to isolate the result of the instruction in the
| xu if it is to fp0 - fp3 and write that value to the USER_FPn
| locations on the stack. The correct destination register is in
| cmdreg2b.
|
bfextu CMDREG2B(%a6){#6:#3},%d0 |get dest register no
cmpil #3,%d0
bgts op2_xi
beqs op2_fp3
cmpil #1,%d0
blts op2_fp0
beqs op2_fp1
op2_fp2:
fmovemx %fp2-%fp2,USER_FP2(%a6)
bras op2_xi
op2_fp1:
fmovemx %fp1-%fp1,USER_FP1(%a6)
bras op2_xi
op2_fp0:
fmovemx %fp0-%fp0,USER_FP0(%a6)
bras op2_xi
op2_fp3:
fmovemx %fp3-%fp3,USER_FP3(%a6)
|
| The frame returned is idle. We must build a busy frame to hold
| the cu state information and fix up etemp.
|
op2_xi:
movel #22,%d0 |clear 23 lwords
clrl (%a7)
op2_loop:
clrl -(%a7)
dbf %d0,op2_loop
movel #0x40600000,-(%a7)
movel L_SCR1(%a6),STAG(%a6)
movel L_SCR2(%a6),CMDREG1B(%a6)
movel L_SCR3(%a6),DTAG(%a6)
moveb #0x6,CU_SAVEPC(%a6)
movel FP_SCR2(%a6),ETEMP(%a6)
movel FP_SCR2+4(%a6),ETEMP_HI(%a6)
movel FP_SCR2+8(%a6),ETEMP_LO(%a6)
movel %d1,-(%a7)
bra op2_com
|
| We have the opclass 2 single source situation.
|
op2_com:
moveb #0x15,%d0
bfins %d0,CMDREG1B(%a6){#0:#6} |opclass 2, double
cmpw #0x407F,ETEMP_EX(%a6) |single +max
bnes case2
movew #0x43FF,ETEMP_EX(%a6) |to double +max
bra finish
case2:
cmpw #0xC07F,ETEMP_EX(%a6) |single -max
bnes case3
movew #0xC3FF,ETEMP_EX(%a6) |to double -max
bra finish
case3:
cmpw #0x3F80,ETEMP_EX(%a6) |single +min
bnes case4
movew #0x3C00,ETEMP_EX(%a6) |to double +min
bra finish
case4:
cmpw #0xBF80,ETEMP_EX(%a6) |single -min
bne fix_done
movew #0xBC00,ETEMP_EX(%a6) |to double -min
bra finish
|
| The frame returned is busy. It is not possible to reconstruct
| the code sequence to allow completion. fpsp_fmt_error causes
| an fline illegal instruction to be executed.
|
| You should replace the jump to fpsp_fmt_error with a jump
| to the entry point used to kill a process.
|
op2_xb:
jmp fpsp_fmt_error
|
| Enter here if the case is not of the situations affected by
| bug #1238, or if the fix is completed, and exit.
|
finish:
fix_done:
rts
|end