306 lines
6 KiB
NASM
306 lines
6 KiB
NASM
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; GPCont.asm - code to allow continuation after GP faults
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.xlist
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include kernel.inc
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include newexe.inc ; ne_restab
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include gpcont.inc
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.list
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if SHERLOCK
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FAULTSTACKFRAME struc
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fsf_BP dw ? ; Saved BP
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fsf_msg dw ? ; Near pointer to message describing fault
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fsf_prev_IP dw ? ; IP of previous fault handler
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fsf_prev_CS dw ? ; CS of previous fault handler
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fsf_ret_IP dw ? ; DPMI fault handler frame follows
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fsf_ret_CS dw ?
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fsf_err_code dw ?
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fsf_faulting_IP dw ?
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fsf_faulting_CS dw ?
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fsf_flags dw ?
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fsf_SP dw ?
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fsf_SS dw ?
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FAULTSTACKFRAME ends
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fsf_DS equ word ptr -10
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fsf_ES equ word ptr -10
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fsf_FS equ word ptr -10
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fsf_GS equ word ptr -10
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;flag bits set in gpRegs
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strCX = 1
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strSI = 2
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strDI = 4
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segDS = 8
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segES = 16
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segFS = 32
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segGS = 64
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ifdef WOW
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sBegin MISCCODE
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externFP DisAsm86
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assumes ds,nothing
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assumes es,nothing
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;-----------------------------------------------------------------------;
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; allows DisAsm86 to be called from _TEXT code segment
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cProc Far_DisAsm86,<PUBLIC,FAR>,<dx>
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parmD cp
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cBegin
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mov ax,cp.off
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mov dx,cp.sel
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cCall <far ptr DisAsm86>,<dx,ax>
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cEnd
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sEnd MISCCODE
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endif ;; WOW
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DataBegin
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externB szGPCont
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szKernel db 6,'KERNEL'
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szUser db 4,'USER'
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szDrWatson db 'DRWATSON'
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externW gpTrying ; retrying current operation
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externW gpEnable ; user has enabled GP continue
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externW gpSafe ; current instruction is safe
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externW gpInsLen ; length of faulting instruction
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externW gpRegs ; bit field of modified regs
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externD pSErrProc ; pointer to SysErrBox in USER
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DataEnd
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externFP IsBadCodePtr
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externFP FarFindExeInfo
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sBegin CODE
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assumes CS,CODE
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ifndef WOW
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externNP DisAsm86
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endif
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externNP GetOwner
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;extern int far pascal SysErrorBox(char far *text, char far *caption,
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; int b1, int b2, int b3);
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SEB_OK = 1 ; Button with "OK".
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SEB_CANCEL = 2 ; Button with "Cancel"
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SEB_YES = 3 ; Button with "&Yes"
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SEB_NO = 4 ; Button with "&No"
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SEB_RETRY = 5 ; Button with "&Retry"
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SEB_ABORT = 6 ; Button with "&Abort"
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SEB_IGNORE = 7 ; Button with "&Ignore"
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SEB_CLOSE = 8 ; Button with "Close"
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SEB_DEFBUTTON = 8000h ; Mask to make this button default
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SEB_BTN1 = 1 ; Button 1 was selected
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SEB_BTN2 = 2 ; Button 1 was selected
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SEB_BTN3 = 3 ; Button 1 was selected
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;Name: int PrepareToParty(char *modName)
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;Desc: Checks whether we can continue the current app by skipping an
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; instruction. If so, it performs the side effects of the
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; instruction. This must be called after a call to DisAsm86() has
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; set the gpXxxx global vars.
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;Bugs: Should do more checking, should check for within a device driver,
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cProc PrepareToParty,<PUBLIC,NEAR>,<si,di>
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parmD modName
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parmD appName
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cBegin
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ReSetKernelDS
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mov ax, [gpEnable] ; User enabled continue
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test ax, 1 ; We know how to continue
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jz ptp_poop
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cld
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dec [modName.off] ; include length byte in compare
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les di, [modName]
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test ax, 4 ; can continue in KERNEL?
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jnz @F
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lea si, szKernel
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mov cx, 7
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repe cmpsb
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jz ptp_poop ; fault in Kernel is fatal
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@@: test ax, 8 ; can continue in USER?
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jnz @F
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mov di, modName.off
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lea si, szUser
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mov cx, 5
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repe cmpsb
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jz ptp_poop ; fault in User is fatal
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@@: cmp [gpTrying], 0
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jne ptp_exit ; AX != 0 - do it again
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cmp pSErrProc.sel, 0 ; Is USER loaded?
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je ptp_poop
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mov ax, dataoffset szGPCont
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mov bx, SEB_CLOSE or SEB_DEFBUTTON ; dumb cmacros
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cCall [pSErrProc],<ds, ax, appName, bx, 0, SEB_IGNORE>
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cmp ax, SEB_BTN3
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jne ptp_poop
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; mov [gpTrying], 100
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jmps ptp_exit ; AX != 0
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ptp_poop: ; every party needs a pooper
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xor ax, ax
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ptp_exit:
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cEnd
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UnSetKernelDS
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cProc SafeDisAsm86,<NEAR,PUBLIC>
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parmD cp
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cBegin
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ReSetKernelDS
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mov [gpSafe], 0 ; assume unsafe
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mov bx, cp.off ; make sure we can disassemble
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add bx, 10 ; at least a 10-byte instruction
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jc sda_exit ; offset wrap-around - failed
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cCall IsBadCodePtr,<seg_cp, bx>
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or ax, ax
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jnz sda_exit
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ifdef WOW
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cCall <far ptr Far_DisAsm86>,<cp>
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else
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cCall DisAsm86,<cp>
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endif
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mov [gpInsLen], ax
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sda_exit:
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cEnd
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; return value in DX:AX and ES:AX (your choice), sets Z flag if failure
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cProc FindSegName,<NEAR,PUBLIC>,<ds>
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parmW segval
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cBegin
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cCall GetOwner,<segval>
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mov dx, ax
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or ax, ax
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jz fsn_exit
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mov es, ax
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mov ax, es:[ne_restab]
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inc ax
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fsn_exit:
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cEnd
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public GPContinue
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GPContinue proc near
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push si ; instruction length
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test [gpEnable], 1
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jz s_fail
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cCall SafeDisAsm86,<[bp].fsf_faulting_CS,[bp].fsf_faulting_IP>
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test [gpSafe], 1
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jz s_fail
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push ds
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push dataoffset szDrWatson
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push 8
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Call FarFindExeInfo
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or ax, ax
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jnz s_fail
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cCall FindSegName,<[bp].fsf_faulting_CS>
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jz s_fail
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push dx
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push ax
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cCall FindSegName,<[bp].fsf_SS>
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jz s_fail4
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push dx
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push ax
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cCall PrepareToParty
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or ax, ax
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jz s_fail
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; Perform side-effects
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mov ax, [gpRegs] ; Invalid value to DS?
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test ax, segDS
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jz @F
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mov [bp].fsf_DS, 0
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@@: test ax, segES ; Invalid value to ES?
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jz @F
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mov [bp].fsf_ES, 0
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if PMODE32
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.386p
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@@: xor bx, bx ; Invalid value to FS?
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test ax, segFS
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jz short @F
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mov fs, bx
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@@: test ax, segGS ; Invalid value to GS?
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jz short @F
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mov gs, bx
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.286p
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endif
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@@:
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test ax, 0
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; check other reg side effects
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mov bx, [gpInsLen] ; Fixup IP for instruction length
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add [bp].fsf_faulting_IP, bx
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mov ax, 1
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jmps s_end
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s_fail4:
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add sp, 4
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s_fail:
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xor ax, ax
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s_end:
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pop si
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ret
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GPContinue endp
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sEnd CODE
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endif ; SHERLOCK
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end
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regs.ip += faultlen; /* set at top of func - don't reuse
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if ((int)gpStack < 0) {
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for (i=0; i<8; i++) stack[i+gpStack] = stack[i];
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} else if (gpStack) {
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for (i=7; i>=0; i--) stack[i+gpStack] = stack[i];
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}
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regs.sp += gpStack << 1;
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if (gpRegs & strCX) {
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len = regs.cx * memSize;
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regs.cx = 0;
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} else len = memSize;
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if (gpRegs & strSI) { /* doesn't handle 32 bit regs
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regs.si += len;
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if (regs.si < (word)len) /* if overflow, set to big value
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regs.si = 0xfff0; /* so global vars in heap don't get
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} /* trashed when we continue
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if (gpRegs & strDI) {
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regs.di += len;
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if (regs.di < (word)len) regs.di = 0xfff0;
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}
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}
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return party;
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} /* Sherlock
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