|
|
;**************************************************************************;* STACK2.ASM;*;* Assembly support code for stack tracing.;*;**************************************************************************
INCLUDE TOOLPRIV.INC INCLUDE TDB.INC
;** External functions
externNP HelperVerifySegexternNP HelperHandleToSel
;** Functions
sBegin CODE assumes CS,CODE
; StackFrameFirst; Returns information about the first stack frame and checks it; for validity as much as possible. The first stack frame is found; by getting the information from the TDB. If this task is active,; or if the task was changed in an unusual way, this information; may be incorrect. If it is, the user must set up the first; CS, IP, and BP, and BPNext in the user structure, log it as the; first stack trace and call StackTraceNext directly.
cProc StackFrameFirst, <NEAR,PUBLIC>, <si,di,ds> parmD lpStack parmW hTDBcBegin ;** Verify that we have a good TDB first ;** Start by verifying the selector mov ax,hTDB ;Get the selector cCall HelperHandleToSel, <ax> ;Convert it to a selector push ax ;Save it mov bx,TDBSize cCall HelperVerifySeg, <ax,bx> pop bx ;Get selector back or ax,ax ;FALSE return? jnz SHORT SF_SelOk ;Selector's OK xor ax,ax ;Return FALSE jmp SHORT SF_EndSF_SelOk:
;** Verify that the TDB signature matches mov ds,bx ;Point with DS cmp ds:[TDB_sig],TDB_SIGNATURE ;Is this really a TDB? jz SF_SigOk ;Must be xor ax,ax ;Return FALSE jmp SHORT SF_EndSF_SigOk:
;** Get the BP value from the task stack and store in structure les di,lpStack ;Get a pointer to the user struct mov ax,ds:[TDB_taskSS] ;Get the SS value mov bx,ds:[TDB_taskSP] ;Get the max segment offset we need add bx,Task_CS + 2 cCall HelperVerifySeg, <ax,bx> ;Make sure we can read all this or ax,ax ;Error? jz SF_End ;Yes, can't do walk lds bx,DWORD PTR ds:[TDB_taskSP] ;Get the SS:SP value mov si,ds:[bx].Task_BP ;Get the BP value from the stack and si,NOT 1 ;Clear the FAR frame bit, if any mov es:[di].st_wBP,si ;Store the BP value mov ax,ds:[bx].Task_IP ;Store initial IP mov es:[di].st_wIP,ax mov ax,ds:[bx].Task_CS ;Store the initial CS mov es:[di].st_wCS,ax
;** Return as much info as possible about this first frame mov ax,hTDB ;Get the TDB handle mov es:[di].st_hTask,ax ;Save in structure mov es:[di].st_wSS,ds ;Save the SS value mov es:[di].st_wFlags,FRAME_FAR ;Force a FAR frame this time
;** Try to verify this stuff xor ax,ax ;In case we need to exit or si,si ;End of the line? jz SF_End ;Nope cmp si,ds:[0ah] ;Compare against stack top jb SF_End ;Fine with top cmp si,ds:[0eh] ;Check against stack bottom jae SF_End ;OK with bottom too mov ax,1 ;Return TRUE
SF_End:cEnd
; StackFrameNext; Returns information in a public structure about the stack frame; pointed to by the BP value passed in. Returns TRUE if the; information seems valid, or FALSE if information could not be; returned.
cProc StackFrameNext, <NEAR,PUBLIC>, <si,di,ds> parmD lpStackcBegin ;** Get pointers to the frame les di,lpStack ;Get a pointer to the structure mov ax,es:[di].st_wSS ;Get the stack segment mov ds,ax ;Point with DS
;** Get the next stack frame mov si,es:[di].st_wBP ;Get the current BP value lea ax,[si + 6] ;Get the max stack probe cmp ax,si ;No stack wraparound allowed jb SN_End ;If below, we have wrapped cCall HelperVerifySeg, <ds,ax> ;Make sure the stack is OK or ax,ax ;OK? jnz @F ;Yes. jmp SHORT SN_End ;Return FALSE@@: mov dx,ds:[si+4] ;DX:CX is the return address mov cx,ds:[si+2] mov bx,ds:[si] ;Get next BP value
;** Zero BP is end of chain xor ax,ax ;In case we need to exit or bx,bx ;End of the line? jz SN_End ;Nope
;** If the new BP is higher on the stack than the old, it's invalid cmp bx,si ;New BP <= Old BP? jbe SN_End ;OK.
;** Make sure we're still on the stack (variables from KDATA.ASM) cmp bx,ds:[0ah] ;Compare against stack top jb SN_End ;Fine with top cmp bx,ds:[0eh] ;Check against stack bottom jae SN_End ;OK with bottom too
;** Return what we can about the frame mov es:[di].st_wSS,ds ;Save the SS value mov es:[di].st_wBP,si ; and the BP value test bx,1 ;Far or near frame? jnz SN_FarFrame ;For sure far if BP is odd
;** Even when BP is not odd, we may have a far frame mov ax,cs ;Get our RPL bits and al,3 ;Mask RPL bits mov ah,dl ;Get frame's RPL bits and ah,3 ;Mask RPL bits cmp al,ah ;If CS is a handle, they won't match jne SN_NearFrame ;Bits don't match lar ax,dx ;Get the access bits test ax,800h ;Is this a code segment? jz SN_NearFrame ;No. MUST be near frame lsl ax,dx ;Get the limit cmp ax,cx ;Inside limit? jbe SN_NearFrame ;No. MUST be near
;** Otherwise, probably is a far frame. It may not be, of course, ;** because this may be a code seg parameterSN_FarFrame: mov es:[di].st_wIP,cx ;Save the offset mov es:[di].st_wCS,dx ; and selector value mov ax,FRAME_FAR ;Tell the user what we did and bx,NOT 1 ;Clear the far frame bit jmp SHORT SN_20 ;Skip near section
;** Must be a near frameSN_NearFrame: mov es:[di].st_wIP,cx ;Save the offset ;Leave the old CS value in mov ax,FRAME_NEAR ;Tell the user what we didSN_20: mov es:[di].st_wFlags,ax ;Save in the structure mov es:[di].st_wBP,bx ;Save BP in the structure mov ax,1 ;Return TRUE
SN_End:cEnd
sEnd
END
|
