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Text File | 1991-09-12 | 22.2 KB | 476 lines | [TEXT/MPS ]

; Leaks.a ; ; Copyright © 1990-91 by Apple Computer, Inc., all rights reserved. ; ; by Bo3b Johnson 10/9/90 ; MS 37-DS ; ; This file is the assembly routines I need in order to interface to the toolbox in ; a sensible fashion. The OS is funky, and there is no good way to do these things ; from Pascal or C. The use of INLINE code is OK, but not always enough. ; ; In order to fashion a good patch to NewPtr/NewHandle, I need to use PC ; relative addressing. The basic problem is that there is no good way to get back ; to the dcmd globals, while the patch is executing. Certainly you can't rely upon ; A5, A6, or A7; and no other registers are available for use. I could stick something ; into AppParms, CurApName, or a number of other atrocities, but I don't own ; any of those spots, and could quite easily end up competing with some other code ; for the spot. In the past, this code patched the Chain trap, since it is not in use, ; but that has competition problems too. If I use PC-relative addressing to get to ; some global information, then this becomes self-modifying code, since I will ; change the code in this block, using a piece of code space as variable storage. ; This seems the most risk-free version for now, notwithstanding certain strident ; if misguided warnings from various groups. It's not enough to tell me not to ; do something, you have to give me an alternative. If you have a better alternative, ; by all means let me know. ; ; I patch the four traps of NewPtr/DisposPtr, NewHandle/DisposHandle; and all ; these pieces are almost identical. The only difference really is the variable being ; used. The basic idea is to have one routine to save off the old address, gotten from ; an NGetTrapAddress; and to save that into the code here, using PC-relative addressing. ; The trap is patched by the Pascal code, and whenever it gets called, it will call here ; to have us call through the old version of the trap. That way it gets control before ; the trap executes, but I still drive the old code. ; ; Realize that the code in this file is getting run mostly during the normal operation ; of the Mac. The stack is whatever the current app is using, as well as that A5 world, ; and stack crawl. I don't where I'll be so, I can't rely on those things. This ; is very different from the code in the dcmd, where it knows the stack it is using is ; in Macsbug, and very small. Pieces of this code will get run a tiny bit from the dcmd, ; since it will call here in order to get access to my global variables, the treeTop, emptyQ, ; and activeState. ; ; One of the goals in this file is to avoid needing an asm version of the record structure ; I use. I really just want to pass around pointers, so that this file can be a little ; more independent of the basic structures. One of the things that's get used though is ; the size of the Stack Crawl array that I pass around. There is a constant here, but ; if it changes in the Pascal code, it should change here. ; By the way, this file looks best if viewed in Palatino 12. include 'SysErr.a' include 'SysEqu.a' include 'Traps.a' proc import AddNewBlock, KillOldBlock ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; ; Storage for the old patch addresses, used to call through once the patch code executes. ; These are essentially globals, used by the asm code. They are specifically not exported, ; so that the Pascal code cannot access them directly. There are a number of interface ; routines I set up so that Pascal can get and set them, but has to go through this file. ; You know, sort of object like. ; pOldNewPtr dc.l 0 pOldNewHandle dc.l 0 pOldDisposPtr dc.l 0 pOldDisposHandle dc.l 0 pEmptyQ dc.l 0 ; list of empty elements available. pTreeTop dc.l 0 ; list of active elements. pActive dc.w 0 ; whether to watch blocks or not. saveEm reg a0-a3/d0-d3 ; a few to keep, since I'm a patch. saveEmSize EQU (8*4) ; 8 registers times 4 bytes each. kCrawlArraySize EQU 8 ; number of stack crawl elements to do. ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; When I'm am setting up the world, I call NGetTrapAddress to get the old version ; of the traps. I need to save that dude off so I can get back there when needed. ; This routine is a handy interface to the high-level world, isolating this asm junk ; from the code. All these routines are the same, just a different variable being affected. ; This hunk uses the PC-Relative addressing mode in order to get the address of the ; variable being set. This allows the code to function without any explicit global ; space, since the code acts like globals here. ; The interface is: ; PROCEDURE SetOldNewPtr (address: LongInt); ; PROCEDURE SetOldNewHandle (address: LongInt); ; PROCEDURE SetOldDisposPtr (address: LongInt); ; PROCEDURE SetOldDisposHandle (address: LongInt); export SetOldNewPtr, SetOldNewHandle, SetOldDisposPtr, SetOldDisposHandle SetOldNewPtr LEA pOldNewPtr,A1 ; the variable to be setting BRA.S Common ; do common stuffing code. SetOldNewHandle LEA pOldNewHandle,A1 ; the variable to set BRA.S Common ; do common stuffing code. SetOldDisposPtr LEA pOldDisposPtr,A1 ; the variable to do BRA.S Common ; do common stuffing code. SetOldDisposHandle LEA pOldDisposHandle,A1 ; the variable Common MOVE.L (SP)+,A0 ; get the return address. MOVE.L (SP)+,(A1) ; save it, pulling parameter too. JMP (A0) ; it's saved, return to high-level. ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; These routines are used by the dcmd in order to get to the global variables, to find the ; treeTop, emptyQ, and activeState. They aren't used by the b-tree management stuff, ; since I always pass these variables to those routines. In addition, the patch code above ; doesn't use this code, since it has direct access to the variables, and does so, using the ; pc-relative approach. ; ; ; GetTreeInfo: ; When desired, the pascal callers may need to get the tree info in order to be able to drive ; the trees for info display reasons. This is an interface to let them see us, but I get to ; pass back the info, rather than have them groping around directly for the data. ; FUNCTION GetTreeTop: TrackEntryPtr; EXTERNAL; ; FUNCTION GetEmptyQ: TrackEntryPtr; EXTERNAL; ; FUNCTION TrackActive: Boolean; EXTERNAL; export GetTreeTop, GetEmptyQ, TrackActive ; GetTreeTop: ; This routine just returns the tree top as a parameter. The assembly stuff just grabs ; these guys directly when it needs to, but the Pascal code comes through this interface ; to get the references. ; FUNCTION GetTreeTop: TreeEntryPtr; EXTERNAL; GetTreeTop MOVE.L pTreeTop,4(SP) ; stuff the return result (pc-relative for source.) RTS ; and return to caller. ; GetEmptyQ: ; FUNCTION GetEmptyQ: TreeEntryPtr; EXTERNAL; GetEmptyQ MOVE.L pEmptyQ,4(SP) ; stuff the return result (pc-relative for source.) RTS ; and return to caller. ; TrackActive: ; Just return the active state as a boolean. This is whether I am actively watching ; and recording block addresses or not. I always want to be able to turn it off sometimes, ; since I want to save a given state for viewing. ; FUNCTION TrackActive: Boolean; EXTERNAL; TrackActive MOVE.W pActive,4(SP) ; stuff function result (pc-relative source). RTS ; and return to caller. ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; As part of the interface to the dcmd, I have setting routines too, to set the variables ; to a known state. This way I don't have to put that sort of tree-based init code in ; assembly. I need to turn it on and off using the dcmd, so it will call here to do so. ; ; PROCEDURE SetTreeTop (address: TrackEntryPtr); EXTERNAL; ; PROCEDURE SetEmptyQ (address: TrackEntryPtr); EXTERNAL; ; PROCEDURE SetActive (state: Boolean); EXTERNAL; export SetTreeTop, SetEmptyQ, SetActive ; PROCEDURE SetTreeTop (address: TrackEntryPtr); EXTERNAL; SetTreeTop MOVE.L (SP)+,A0 ; the return address, for safe keeping. LEA pTreeTop,A1 ; the variable I need to set, pc-relative. MOVE.L (SP)+,(A1) ; save off the new variable, clearing parameter. JMP (A0) ; and return to caller. ; PROCEDURE SetEmptyQ (address: TrackEntryPtr); EXTERNAL; SetEmptyQ MOVE.L (SP)+,A0 ; the return address, for safe keeping. LEA pEmptyQ,A1 ; the variable I need to set, pc-relative. MOVE.L (SP)+,(A1) ; save off the new variable, clearing parameter. JMP (A0) ; and return to caller. ; PROCEDURE SetActive (state: Boolean); EXTERNAL; SetActive MOVE.L (SP)+,A0 ; the return address, for safe keeping. LEA pActive,A1 ; the variable I need to set, pc-relative. MOVE.W (SP)+,(A1) ; save off the new state, clearing parameter. JMP (A0) ; and return to caller. ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; This is the patch code for the various pieces I patch. This is in assembly ; since I need to preserve registers and do some other low level jacking around, ; like trying to do a stack crawl whenever I allocate blocks. These routines are the ; actual code that gets called when one of the four traps is executed. ; WatchNewPtr: ; The routine to patch the NewPtr trap, and I get first dibs at getting the info I want ; out of the registers. I need to save off the size to start with, since D0 gets pounded ; to the return result once I actually call the old NewPtr code. Once I have that ; safely stowed on the stack, I call the old code, using the PC-relative addressing in ; order to get the old address that I'm supposed to call. This was set up when the ; dcmd called me to save off the value. When that old NewPtr junk returns, I get ; the actual address allocated, if enough memory, then do the funky stack crawl, ; and finally pass all these tidbits off to the AddNewBlock routine. export WatchNewPtr WatchNewPtr MOVE.L D0,-(SP) ; save size off. ; First, allocate the pointer. PEA @1 ; coming back here, as return address. MOVE.L pOldNewPtr,-(SP) ; the old address I am going to, RTS ; JMP there, when it RTSes I come back @1 ; --here. ; A0 is set up as the handle to track, add it to the b-tree list. If it is NIL, meaning the ; NewPtr failed, then don't add it to the list, it cannot be disposed. I do the save of ; registers here, after the allocation of memory, so that I can save the registers as they ; are coming out of the call, not going in. MOVEM.L saveEm,-(SP) ; save registers in trap patches. MOVE.W pActive,D0 ; is it turned on to watch? BEQ.S @exit ; if not, skip saving. CMP.L #0,A0 ; is it a NIL return? BEQ.S @exit ; if so, bag it. ; Now I am supposed to track the block that was just allocated, so I need to call the AddNewBlock ; routine in order to tie it in. In order to set up the parameters for the call, I have to do a stack ; crawl, to get the previous return addresses. The problem of course is that the stack crawl has ; no known length, and is often less than kCrawlArraySize. So... I have to look at each one as ; it is created, and make sure that it is valid; and continue no farther when I find a bad one. If ; I go on, I risk dying from a bus error, since the addresses won't chain nicely in all cases. I will call ; the routine, where the stackToAdd is an array, built on the stack: ; PROCEDURE AddNewBlock (addressToAdd, sizeToAdd: LongInt; stackToAdd: StackArray; ; VAR treeTop, emptyQ: TrackEntryPtr); MOVE.L saveEmSize(SP),D1 ; retrieve size parameter. MOVEQ #kCrawlArraySize-1,D0 ; for 8 times in DBRA loop. @Clr CLR.L -(SP) ; make a stack crawl array on the stack, DBRA D0,@Clr ; by looping 8 times. (all zeroed.) MOVE.L SP,A1 ; the address of the stack crawl array. ; Now with that array built and zeroed I want to add the parameters to the stack. If I have to ; bail out of the stack crawl before it hits all kCrawlArraySize elements, then the rest have ; already been zeroed, which marks them as non-valid. I'm going to set up for the call ; here, so the registers are freed up for doing the funky stack crawl checks. MOVE.L A0,-(SP) ; addressToAdd: block being added to tracker. MOVE.L D1,-(SP) ; sizeToAdd: size of block being tracked. MOVE.L A1,-(SP) ; stackToAdd: the address of the array of crawls. PEA pTreeTop ; treeTop: bTree top. (as var parameters) PEA pEmptyQ ; emptyQ: top of empties list. ; All the parameters are set up, do the stack crawl checks. This will modify the stackToAdd ; array, for each crawl that is valid. The stackToAdd is still in A1. MOVE.L A6,A0 ; get stack frame head. MOVEQ #kCrawlArraySize-1,D0 ; doing a loop for 8 stack crawls. @Frame CMP.L A7,A0 ; make sure it is greater than a7 BLO.S @noFrame ; skip any more if not valid. CMP.L CurStackBase,A0 ; make sure it is less than base of stack, BHI.S @noFrame ; If not, skip checking rest of crawl. ; It's a valid frame, go ahead and save off the return address in the array. A1 is the address of ; the next array element to set. It is autoincremented to the next entry each time I can stow a ; valid pc return address. MOVE.L 4(A0),(A1)+ ; the pc return address for this frame, into Array. MOVE.L (A0),A0 ; next stack frame back. (as a big chain) DBRA D0,@Frame ; loop for all 8. ; If there was a bogus frame in there somewhere, I bailed out to here. All the rest of the stackArray ; entries are nil though, so it doesn't matter, I'll just call the AddNewBlock anyway. I got here if ; all the entries were valid, too, and just fell out of the DBRA loop. @noFrame BSR AddNewBlock ; track a new block on heap. ADD.L #kCrawlArraySize*4,SP ; kill the crawl array from stack. @exit MOVEM.L (SP)+,saveEm ; save registers in trap patches. ADDQ #4,SP ; kill size that was saved. (from D0) RTS ; Return to caller of NewPtr. ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; WatchDisposPtr: ; This routine is my patch to DisposPtr, and it watches the address being passed in ; A0 to see if it is one of the blocks I am tracking in the table. If it is, I release that ; record from my b-Tree code, since it is obviously not a leak when it is released. ; If the block is not found, then I just skip it too, since there are presumably a ; ton of blocks that I didn't see being allocated, since I'm not watching from the ; start of the system. This is a head patch, since I do my thing, then jump to ; the old routine. When that routine finishes, it will call RTS and go back to ; wherever I was called from. export WatchDisposPtr WatchDisposPtr MOVEM.L saveEm,-(SP) ; save registers in trap patches. MOVE.W pActive,D0 ; is it turned on to watch? BEQ.S CallOldDisposePtr ; if not, skip saving. MOVE.L A0,-(SP) ; block being added to tracker. PEA pTreeTop ; bTree top. (as var parameters) PEA pEmptyQ ; top of empties list. BSR KillOldBlock ; get it out of my dang table CallOldDisposePtr MOVEM.L (SP)+,saveEm ; save registers in trap patches. MOVE.L pOldDisposPtr,-(SP) ; get address of old routine. RTS ; and jump there. ; when it RTSes, I'll go back to the caller. ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; WatchNewHandle: ; The routine to patch the NewHandle trap, and I get first dibs at getting the info I want ; out of the registers. I need to save off the size to start with, since D0 gets pounded ; to the return result once I actually call the old NewHandle code. Once I have that ; safely stowed on the stack, I call the old code, using the PC-relative addressing in ; order to get the old address that I'm supposed to call. This was set up when the ; dcmd called me to save off the value. When that old NewHandle junk returns, I get ; the actual address allocated, if enough memory, then do the funky stack crawl, ; and finally pass all these tidbits off to the AddNewBlock routine. The AddNewBlock ; doesn't differentiate between pointers being watched or handles being watched, it is ; just an address. export WatchNewHandle WatchNewHandle MOVE.L D0,-(SP) ; save size off. ; First, allocate the handle. PEA @1 ; coming back here, as return address. MOVE.L pOldNewHandle,-(SP) ; the old address I am going to, RTS ; JMP there, when it RTSes I come back @1 ; --here. ; A0 is set up as the handle to track, add it to the b-tree list. If it is NIL, meaning the ; NewHandle failed, then don't add it to the list, it cannot be disposed. I do the save of ; registers here, after the allocation of memory, so that I can save the registers as they ; are coming out of the call, not going in. MOVEM.L saveEm,-(SP) ; save registers in trap patches. MOVE.W pActive,D0 ; is it turned on to watch? BEQ.S @exit ; if not, skip saving. CMP.L #0,A0 ; is it a NIL return? BEQ.S @exit ; if so, bag it. ; Now I am supposed to track the block that was just allocated, so I need to call the AddNewBlock ; routine in order to tie it in. In order to set up the parameters for the call, I have to do a stack ; crawl, to get the previous return addresses. The problem of course is that the stack crawl has ; no known length, and is often less than kCrawlArraySize. So... I have to look at each one as ; it is created, and make sure that it is valid; and continue no farther when I find a bad one. If ; I go on, I risk dying from a bus error, since the addresses won't chain nicely in all cases. I will call ; the routine, where the stackToAdd is an array, built on the stack: ; PROCEDURE AddNewBlock (addressToAdd, sizeToAdd: LongInt; stackToAdd: StackArray; ; VAR treeTop, emptyQ: TrackEntryPtr); MOVE.L saveEmSize(SP),D1 ; retrieve size parameter. MOVEQ #kCrawlArraySize-1,D0 ; for 8 times in DBRA loop. @Clr CLR.L -(SP) ; make a stack crawl array on the stack, DBRA D0,@Clr ; by looping 8 times. (all zeroed.) MOVE.L SP,A1 ; the address of the stack crawl array. ; Now with that array built and zeroed I want to add the parameters to the stack. If I have to ; bail out of the stack crawl before it hits all kCrawlArraySize elements, then the rest have ; already been zeroed, which marks them as non-valid. I'm going to set up for the call ; here, so the registers are freed up for doing the funky stack crawl checks. MOVE.L A0,-(SP) ; addressToAdd: block being added to tracker. MOVE.L D1,-(SP) ; sizeToAdd: size of block being tracked. MOVE.L A1,-(SP) ; stackToAdd: the address of the array of crawls. PEA pTreeTop ; treeTop: bTree top. (as var parameters) PEA pEmptyQ ; emptyQ: top of empties list. ; All the parameters are set up, do the stack crawl checks. This will modify the stackToAdd ; array, for each crawl that is valid. The stackToAdd is still in A1. MOVE.L A6,A0 ; get stack frame head. MOVEQ #kCrawlArraySize-1,D0 ; doing a loop for 8 stack crawls. @Frame CMP.L A7,A0 ; make sure it is greater than a7 BLO.S @noFrame ; skip any more if not valid. CMP.L CurStackBase,A0 ; make sure it is less than base of stack, BHI.S @noFrame ; If not, skip checking rest of crawl. ; It's a valid frame, go ahead and save off the return address in the array. A1 is the address of ; the next array element to set. It is autoincremented to the next entry each time I can stow a ; valid pc return address. MOVE.L 4(A0),(A1)+ ; the pc return address for this frame, into Array. MOVE.L (A0),A0 ; next stack frame back. (as a big chain) DBRA D0,@Frame ; loop for all 8. ; If there was a bogus frame in there somewhere, I bailed out to here. All the rest of the stackArray ; entries are nil though, so it doesn't matter, I'll just call the AddNewBlock anyway. I got here if ; all the entries were valid, too, and just fell out of the DBRA loop. @noFrame BSR AddNewBlock ; track a new block on heap. ADD.L #kCrawlArraySize*4,SP ; kill the crawl array from stack. @exit MOVEM.L (SP)+,saveEm ; save registers in trap patches. ADDQ #4,SP ; kill size that was saved. (from D0) RTS ; Return to caller of NewPtr. ; —————————————————————————————————————————————————————————————————————————————————————————————————— ; WatchDisposHandle: ; This routine is my patch to DisposHandle, and it watches the address being passed in ; A0 to see if it is one of the blocks I am tracking in the table. If it is, I release that ; record from my b-Tree code, since it is obviously not a leak when it is released. ; If the block is not found, then I just skip it too, since there are presumably a ; ton of blocks that I didn't see being allocated, since I'm not watching from the ; start of the system. This is a head patch, since I do my thing, then jump to ; the old routine. When that routine finishes, it will call RTS and go back to ; wherever I was called from. export WatchDisposHandle WatchDisposHandle MOVEM.L saveEm,-(SP) ; save registers in trap patches. MOVE.W pActive,D0 ; is it turned on to watch? BEQ.S CallOldDisposeHandle ; if not, skip saving. MOVE.L A0,-(SP) ; block being added to tracker. PEA pTreeTop ; bTree top. (as var parameters) PEA pEmptyQ ; top of empties list. BSR KillOldBlock ; get it out of my dang table CallOldDisposeHandle MOVEM.L (SP)+,saveEm ; save registers in trap patches. MOVE.L pOldDisposHandle,-(SP) ; get address of old routine. RTS ; and jump there. ; when it RTSes, I'll go back to the caller. endproc ; —————————————————————————————————————————————————————————————————————————————————————————————————— end