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ecm int24 fix #215

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Merged
merged 5 commits into from
Aug 23, 2025
Merged

ecm int24 fix #215

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330d420
entry.asm: fix Critical Error caller 386 registers
ecm-pushbx Aug 22, 2025
49432df
entry.asm: fix int 24h stack changes to ensure interrupt lockout (#213)
ecm-pushbx Aug 22, 2025
4fea8ad
entry.asm: allow critical error Abort on self-parented process
ecm-pushbx Aug 22, 2025
4d30943
rename byte [SDA + 25Ch] from _tsr to _term_type, fix int 24h rc
ecm-pushbx Aug 22, 2025
811708f
set byte [SDA + 39h] during process termination, turn abort to fail
ecm-pushbx Aug 22, 2025
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10 changes: 8 additions & 2 deletions hdr/stacks.inc
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,8 @@ irp_hi equ 26
; error 1 2 3
%macro Protect386Registers 0
%endmacro

%assign Size386Registers 0

%macro RestoreSP 0
mov sp, bp
Expand All @@ -151,8 +153,10 @@ irp_hi equ 26
push gs
%endmacro

%assign Size386Registers 4

%macro RestoreSP 0
lea sp, [bp-4]
lea sp, [bp - Size386Registers]
%endmacro

%macro Restore386Registers 0
Expand All @@ -176,8 +180,10 @@ irp_hi equ 26
pop dx
%endmacro

%assign Size386Registers 6

%macro RestoreSP 0
lea sp, [bp-6]
lea sp, [bp - Size386Registers]
%endmacro

%macro Restore386Registers 0
Expand Down
43 changes: 36 additions & 7 deletions kernel/entry.asm
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Expand Up @@ -41,6 +41,8 @@ segment HMA_TEXT
extern _user_r
extern _ErrorMode
extern _InDOS
extern _term_type
extern _abort_progress
%IFDEF WIN31SUPPORT
extern _winInstanced
%ENDIF ; WIN31SUPPORT
Expand Down Expand Up @@ -264,11 +266,11 @@ reloc_call_int21_handler:
; NB: At this point, SS != DS and won't be set that way
; until later when which stack to run on is determined.
;
int21_reentry:
Protect386Registers
mov dx,[cs:_DGROUP_]
mov ds,dx

mov byte [_term_type], 0 ; reset termination type
int21_reentry: ; entered here from int 24h abort, ds = dx => DGROUP
Protect386Registers
cmp ah,33h
je int21_user
cmp ah,50h
Expand Down Expand Up @@ -611,6 +613,8 @@ CritErr05:
mov bp,sp
push si
push di
Protect386Registers

;
; Get parameters
;
Expand Down Expand Up @@ -644,8 +648,8 @@ CritErr05:
;
; switch to user's stack
;
mov ss,[es:PSP_USERSS]
mov bp,[es:PSP_USERSP]
mov ss,[es:PSP_USERSS]
RestoreSP
Restore386Registers
mov bp,cx
Expand All @@ -659,6 +663,13 @@ CritErr05:
;
cld
cli
Protect386Registers
; ecm: The extended stack frame must be restored here
; in case the response isn't Abort. The int 21h handler
; will expect the extended stack frame to be still
; intact, but the stack written by the int 24h (even
; only the int instruction) will have overwritten it.

mov bp, [cs:_DGROUP_]
mov ds,bp
mov ss,bp
Expand All @@ -672,7 +683,13 @@ CritErr05:
pop word [es:PSP_USERSP]
pop word [es:PSP_USERSS]
mov bp, sp
mov ah, byte [bp+4+4] ; restore old AH from nFlags
mov ah, byte [bp + 4 + 4 + Size386Registers]
; restore old AH from nFlags
; ecm: One 4 is the displacement of nFlags from the
; usual bp, the other 4 accounts for the si and di
; on the stack, the Size386Registers is added to
; skip the fs and gs (OpenWatcom 386 build) or high
; words that are a part of the stack frame, if any.
sti ; Enable interrupts
;
; clear flags
Expand Down Expand Up @@ -715,6 +732,8 @@ CritErr30:

CritErrExit:
xor ah,ah ; clear out top for return

Restore386Registers
pop di
pop si
pop bp
Expand All @@ -724,18 +743,28 @@ CritErrExit:
; Abort processing.
;
CritErrAbort:
test byte [_abort_progress], -1
mov al, FAIL
jnz CritErrExit
%if 0
mov ax,[_cu_psp]
mov es,ax
cmp ax,[es:PSP_PARENT]
mov al,FAIL
jz CritErrExit
; ecm: This check is done by (E)DR-DOS, but not MS-DOS.
; Therefore, disable it and terminate the self-parented
; process here like any other.
%endif
cli
mov bp,word [_user_r+2] ;Get frame
mov ss,bp
mov ax,word [_user_r+2] ;Get frame
mov bp,word [_user_r]
mov ss,ax
mov sp,bp
mov byte [_ErrorMode],1 ; flag abort
mov ax,4C00h
mov [bp+reg_ax],ax
sti
mov byte [_term_type], 2 ; set int 24h abort error
mov dx, ds
jmp int21_reentry ; restart the system call
3 changes: 2 additions & 1 deletion kernel/globals.h
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Expand Up @@ -307,7 +307,8 @@ extern BYTE
ASM internal_data[], /* sda areas */
ASM swap_always[], /* " " */
ASM swap_indos[], /* " " */
ASM tsr, /* true if program is TSR */
ASM term_type, /* 0 normal, 1 ^C, 2 int 24h, 3 TSR */
ASM abort_progress, /* set during process termination */
ASM break_flg, /* true if break was detected */
ASM break_ena; /* break enabled flag */
extern void FAR * ASM dta; /* Disk transfer area (kludge) */
Expand Down
17 changes: 5 additions & 12 deletions kernel/inthndlr.c
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Expand Up @@ -811,7 +811,7 @@ VOID ASMCFUNC int21_service(iregs FAR * r)
case 0x31:
DosMemChange(cu_psp, lr.DX < 6 ? 6 : lr.DX, 0);
return_code = lr.AL | 0x300;
tsr = TRUE;
term_type = 3; /* ecm: TSR terminate */
return_user();
break;

Expand Down Expand Up @@ -1104,18 +1104,11 @@ VOID ASMCFUNC int21_service(iregs FAR * r)

/* End Program */
case 0x4c:
tsr = FALSE;
rc = 0;
if (ErrorMode)
{
ErrorMode = FALSE;
rc = 0x200;
}
else if (break_flg)
{
if (break_flg) {
break_flg = FALSE;
rc = 0x100;
term_type = 1;
}
rc = term_type << 8;
return_code = lr.AL | rc;
if (DosMemCheck() != SUCCESS)
panic("MCB chain corrupted");
Expand Down Expand Up @@ -1784,7 +1777,7 @@ VOID INRPT FAR int23_handler(int es, int ds, int di, int si, int bp,
int sp, int bx, int dx, int cx, int ax,
int ip, int cs, int flags)
{
tsr = FALSE;
term_type = 1;
return_mode = 1;
return_code = -1;
mod_sto(CTL_C);
Expand Down
9 changes: 7 additions & 2 deletions kernel/kernel.asm
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Expand Up @@ -796,6 +796,7 @@ _DayOfWeek db 2 ; 36 - day of week
_console_swap db 0 ; 37 console swapped during read from dev
global _dosidle_flag
_dosidle_flag db 1 ; 38 - safe to call int28 if nonzero
global _abort_progress
_abort_progress db 0 ; 39 - abort in progress
global _CharReqHdr
_CharReqHdr:
Expand Down Expand Up @@ -838,8 +839,12 @@ _Server_Call db 0 ;252 - Server call Func 5D sub 0
; Pad to 05CCh
times (25ch - ($ - _internal_data)) db 0

global _tsr ; used by break and critical error
_tsr db 0 ;25C - handlers during termination
global _term_type ; used by break and critical error
_term_type db 0 ;25C - handlers during termination
; ecm: 00h = normal terminate,
; 01h = control-c terminate,
; 02h = critical error abort,
; 03h = TSR terminate
db 0 ;25D - padding
global term_psp
term_psp dw 0 ;25E - 0??
Expand Down
7 changes: 7 additions & 0 deletions kernel/procsupt.asm
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Expand Up @@ -34,6 +34,7 @@
extern _user_r

extern _break_flg ; break detected flag
extern _term_type
extern _int21_handler ; far call system services

%include "stacks.inc"
Expand Down Expand Up @@ -257,6 +258,12 @@ _spawn_int23:
push ds ;; we need DGROUP
mov ds, [cs:_DGROUP_]
inc byte [_break_flg]
mov byte [_term_type], 1
; ecm: This is overwritten in the int 21h handler,
; but is passed from the int 23h caller to the
; terminate code in MS-DOS by writing this.
; For us, break_flg is used in function 4Ch to
; re-set term_type to 1 later.
pop ds

xor ah, ah ;; clear ah --> perform DOS-00 --> terminate
Expand Down
6 changes: 5 additions & 1 deletion kernel/task.c
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Expand Up @@ -588,12 +588,14 @@ VOID return_user(void)
setvec(0x23, p->ps_isv23);
setvec(0x24, p->ps_isv24);

abort_progress = -1;

/* And free all process memory if not a TSR return */
network_redirector(REM_PROCESS_END);
/* might be a good idea to do that after closing
but doesn't help NET either TE */

if (!tsr && p->ps_parent != cu_psp)
if (term_type != 3 && p->ps_parent != cu_psp)
{
network_redirector(REM_CLOSEALL);
for (i = 0; i < p->ps_maxfiles; i++)
Expand All @@ -607,6 +609,8 @@ VOID return_user(void)
cu_psp = p->ps_parent;
q = MK_FP(cu_psp, 0);

abort_progress = 0;

irp = (iregs FAR *) q->ps_stack;

irp->CS = FP_SEG(p->ps_isv22);
Expand Down