[Vm-dev] VM Maker: VMMaker.oscog-eem.3025.mcz

commits at source.squeak.org commits at source.squeak.org
Wed Aug 4 03:14:22 UTC 2021

Eliot Miranda uploaded a new version of VMMaker to project VM Maker:

==================== Summary ====================

Name: VMMaker.oscog-eem.3025
Author: eem
Time: 3 August 2021, 8:13:42.437671 pm
UUID: f05011b2-d8fc-4b98-aeb2-ee7f640969c1
Ancestors: VMMaker.oscog-eem.3024

Cogit: Fix a bad slip with SPReg ~= NativeSPReg platforms (ARMv8) and FastCCall primitives.  The NativeSPReg must be restored to CStackPointer after calling the primitive/calling checkForAndFollowForwardedPrimitiveState, otherwise an OS interrupt will call whereever the NativeSPReg was left and the Smalltalk stack will be damaged.

=============== Diff against VMMaker.oscog-eem.3024 ===============

Item was changed:
  ----- Method: SimpleStackBasedCogit>>compileOnStackExternalPrimitive:flags: (in category 'primitive generators') -----
  compileOnStackExternalPrimitive: primitiveRoutine flags: flags
  	"Compile a fast call of a C primitive using the current stack page, avoiding the stack switch except on failure.
  	 This convention still uses stackPointer and argumentCount to access operands.  Push all operands to the stack,
  	 assign stackPointer, argumentCount, and zero primFailCode.  Make the call (saving a LinkReg if required).
  	 Test for failure and return.  On failure on Spur, if there is an accessor depth, assign framePointer and newMethod,
  	 do the stack switch, call checkForAndFollowForwardedPrimitiveState, and loop back if forwarders are found.
  	 Fall through to frame build."
  	<option: #SpurObjectMemory>
  	<var: #primitiveRoutine declareC: 'void (*primitiveRoutine)(void)'>
  	| calleeSavedRegisterMask linkRegSaveRegister spRegSaveRegister jmp retry |
  	self assert: (objectRepresentation hasSpurMemoryManagerAPI and: [flags anyMask: PrimCallOnSmalltalkStack]).
  	self deny: (backEnd hasVarBaseRegister
  				and: [self register: VarBaseReg isInMask: ABICallerSavedRegisterMask]).
  	(coInterpreter recordFastCCallPrimTraceForMethod: methodObj) ifTrue:
  		[self genFastPrimTraceUsing: ClassReg and: SendNumArgsReg].
  	"Clear the primFailCode and set argumentCount"
  	self MoveCq: 0 R: TempReg.
  	self MoveR: TempReg Aw: coInterpreter primFailCodeAddress.
  	methodOrBlockNumArgs ~= 0 ifTrue:
  		[self AddCq: methodOrBlockNumArgs R: TempReg]. "As small or smaller than move on most archs"
  	self MoveR: TempReg Aw: coInterpreter argumentCountAddress.
  	self genExternalizeStackPointerForFastPrimitiveCall.
  	"We may need to save LinkReg and/or SPReg, and given the stack machinations
  	  it is much easier to save them in callee saved registers than on the stack itself."
  	calleeSavedRegisterMask := ABICalleeSavedRegisterMask bitClear: (self registerMaskFor: ClassReg).
  	backEnd hasLinkRegister ifTrue:
  		[linkRegSaveRegister := self availableRegisterOrNoneIn: calleeSavedRegisterMask.
  		 self deny: linkRegSaveRegister = NoReg.
  		 self MoveR: LinkReg R: linkRegSaveRegister.
  		 calleeSavedRegisterMask := calleeSavedRegisterMask bitClear: (self registerMaskFor: linkRegSaveRegister)].
  	spRegSaveRegister := NoReg.
  	(SPReg ~= NativeSPReg
  	 and: [(self isCalleeSavedReg: SPReg) not]) ifTrue:
  		[spRegSaveRegister := self availableRegisterOrNoneIn: calleeSavedRegisterMask.
  		 self deny: spRegSaveRegister = NoReg.
  		 self MoveR: SPReg R: spRegSaveRegister].
  	retry := self Label.
  	(flags anyMask: PrimCallOnSmalltalkStackAlign2x)
  		ifTrue: [self AndCq: (objectMemory wordSize * 2 - 1) bitInvert R: SPReg R: NativeSPReg]
  			[SPReg ~= NativeSPReg ifTrue:
  				[backEnd genLoadNativeSPRegWithAlignedSPReg]].
  	self CallFullRT: primitiveRoutine.
  	self MoveAw: coInterpreter primFailCodeAddress R: TempReg.
  	spRegSaveRegister ~= NoReg ifTrue:
  		[self MoveR: spRegSaveRegister R: SPReg].
  	self CmpCq: 0 R: TempReg.
  	jmp := self JumpNonZero: 0.
+ 	"Remember to restore the native stack pointer to point to the C stack,
+ 	 otherwise the Smalltalk frames will get overwritten on an interrupt."
+ 	SPReg ~= NativeSPReg ifTrue:
+ 		[backEnd genLoadCStackPointer].
  	"At this point the primitive has cut back stackPointer to point to the result."
  	self MoveAw: coInterpreter stackPointerAddress R: TempReg.
  	"get result and restore retpc"
  	backEnd hasLinkRegister
  			[self MoveMw: 0 r: TempReg R: ReceiverResultReg;
  				AddCq: objectMemory wordSize R: TempReg R: SPReg;
  				MoveR: linkRegSaveRegister R: LinkReg]
  			[| retpcOffset |
  			"The original retpc is (argumentCount + 1) words below stackPointer."
  			 retpcOffset := (methodOrBlockNumArgs + 1 * objectMemory wordSize) negated.
  			 self MoveMw: retpcOffset r: TempReg R: ClassReg; "get retpc"
  				MoveR: TempReg R: SPReg;
  			 	MoveMw: 0 r: TempReg R: ReceiverResultReg;
  				MoveR: ClassReg Mw: 0 r: TempReg "put it back on stack for the return..."].
  	self RetN: 0.
  	jmp jmpTarget: self Label.
  	(coInterpreter accessorDepthForExternalPrimitiveMethod: methodObj) >= 0
  			[| skip |
  			 "Given that following primitive state to the accessor depth is recursive, we're asking for
  			  trouble if we run the fixup on the Smalltalk stack page.  Run it on the full C stack instead.
  			 This won't be a performance issue since primitive failure should be very rare."
  			self MoveR: FPReg Aw: coInterpreter framePointerAddress.
  			self MoveCw: primitiveRoutine asInteger R: TempReg.
  			self MoveR: TempReg Aw: coInterpreter primitiveFunctionPointerAddress.
  			methodLabel addDependent:
  				(self annotateAbsolutePCRef:
  					(self MoveCw: methodLabel asInteger R: ClassReg)).
  			self MoveMw: (self offset: CogMethod of: #methodObject) r: ClassReg R: TempReg.
  			self MoveR: TempReg Aw: coInterpreter newMethodAddress.
  			self genLoadCStackPointersForPrimCall.
  			self CallFullRT: (self cCode: [#checkForAndFollowForwardedPrimitiveState asUnsignedIntegerPtr]
  								   inSmalltalk: [self simulatedTrampolineFor: #checkForAndFollowForwardedPrimitiveState]).
  			backEnd genLoadStackPointersForFastPrimCall: ClassReg.
  			self CmpCq: 0 R: ABIResultReg.
  			skip := self JumpZero: 0.
  			self MoveCq: 0 R: TempReg.
  			self MoveR: TempReg Aw: coInterpreter primFailCodeAddress.
  			self Jump: retry.
  			skip jmpTarget: self Label]
  		ifFalse: "must reload SPReg to undo any alignment change,"
  			[(flags anyMask: PrimCallOnSmalltalkStackAlign2x) ifTrue:
  				[backEnd genLoadStackPointersForFastPrimCall: ClassReg]].
+ 	"Remember to restore the native stack pointer to point to the C stack,
+ 	 otherwise the Smalltalk frames will get overwritten on an interrupt."
+ 	SPReg ~= NativeSPReg ifTrue:
+ 		[backEnd genLoadCStackPointer].
  	"The LinkRegister now contains the return address either of the primitive call or of checkForAndFollowForwardedPrimitiveState.
  	 It must be restored to the return address of the send invoking this primtiive method."
  	backEnd hasLinkRegister ifTrue:
  		[self MoveR: linkRegSaveRegister R: LinkReg].
  	"Finally remember to reload ReceiverResultReg if required.  Even if
  	 arguments have been pushed, the prolog sequence assumes it is live."
  	(self register: ReceiverResultReg isInMask: ABICallerSavedRegisterMask) ifTrue:
  		[self MoveMw: (methodOrBlockNumArgs + (backEnd hasLinkRegister ifTrue: [0] ifFalse: [1])) * objectMemory wordSize
  			r: SPReg
  			R: ReceiverResultReg].
  	"continue to frame build..."

More information about the Vm-dev mailing list