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// TITLE("Miscellaneous Exception Handling")//++//// Copyright (c) 1990 Microsoft Corporation// Copyright (c) 1992 Digital Equipment Corporation//// Module Name://// xcptmisc.s//// Abstract://// This module implements miscellaneous routines that are required to// support exception handling. Functions are provided to call an exception// handler for an exception, call an exception handler for unwinding, call// an exception filter, call a termination handler, and get the caller's// stack limits.//// Author://// David N. Cutler (davec) 12-Sep-1990//// Environment://// Any mode.//// Revision History://// Thomas Van Baak (tvb) 7-May-1992//// Adapted for Alpha AXP.////--
#include "ksalpha.h"
//// Define call frame for calling exception handlers.//
.struct 0CfRa: .space 8 // saved return addressCfA3: .space 8 // save area for argument a3 .space 0 * 8 // 16-byte stack alignmentCfFrameLength: // length of stack frame SBTTL("Execute Handler for Exception")//++//// EXCEPTION_DISPOSITION// RtlpExecuteHandlerForException (// IN PEXCEPTION_RECORD ExceptionRecord,// IN ULONG EstablisherFrame,// IN OUT PCONTEXT ContextRecord,// IN OUT PDISPATCHER_CONTEXT DispatcherContext,// IN PEXCEPTION_ROUTINE ExceptionRoutine// )//// Routine Description://// This function allocates a call frame, stores the establisher frame// pointer in the frame, establishes an exception handler, and then calls// the specified exception handler as an exception handler. If a nested// exception occurs, then the exception handler of this function is called// and the establisher frame pointer is returned to the exception dispatcher// via the dispatcher context parameter. If control is returned to this// routine, then the frame is deallocated and the disposition status is// returned to the exception dispatcher.//// Arguments://// ExceptionRecord (a0) - Supplies a pointer to an exception record.//// EstablisherFrame (a1) - Supplies the frame pointer of the establisher// of the exception handler that is to be called.//// ContextRecord (a2) - Supplies a pointer to a context record.//// DispatcherContext (a3) - Supplies a pointer to the dispatcher context// record.//// ExceptionRoutine (a4) - Supplies a pointer to the exception handler that// is to be called.//// Return Value://// The disposition value returned by the specified exception handler is// returned as the function value.////--
//// N.B. This function specifies its own private exception handler.//
EXCEPTION_HANDLER(RtlpExceptionHandler)
NESTED_ENTRY(RtlpExecuteHandlerForException, CfFrameLength, zero)
lda sp, -CfFrameLength(sp) // allocate stack frame stq ra, CfRa(sp) // save return address
PROLOGUE_END
//// Save the address of the dispatcher context record in our stack frame so// that our own exception handler (not the one we're calling) can retrieve it.//
stq a3, CfA3(sp) // save address of dispatcher context
//// Now call the exception handler and return its return value as ours.//
bic a4, 3, a4 // clear low-order bits (IEEE mode) jsr ra, (a4) // call exception handler
ldq ra, CfRa(sp) // restore return address lda sp, CfFrameLength(sp) // deallocate stack frame ret zero, (ra) // return
.end RtlpExecuteHandlerForException SBTTL("Local Exception Handler")//++//// EXCEPTION_DISPOSITION// RtlpExceptionHandler (// IN PEXCEPTION_RECORD ExceptionRecord,// IN ULONG EstablisherFrame,// IN OUT PCONTEXT ContextRecord,// IN OUT PDISPATCHER_CONTEXT DispatcherContext// )//// Routine Description://// This function is called when a nested exception occurs. Its function// is to retrieve the establisher frame pointer from its establisher's// call frame, store this information in the dispatcher context record,// and return a disposition value of nested exception.//// Arguments://// ExceptionRecord (a0) - Supplies a pointer to an exception record.//// EstablisherFrame (a1) - Supplies the frame pointer of the establisher// of this exception handler.//// ContextRecord (a2) - Supplies a pointer to a context record.//// DispatcherContext (a3) - Supplies a pointer to the dispatcher context// record.//// Return Value://// A disposition value ExceptionNestedException is returned if an unwind// is not in progress. Otherwise a value of ExceptionContinueSearch is// returned.////--
LEAF_ENTRY(RtlpExceptionHandler)
ldl t0, ErExceptionFlags(a0) // get exception flags and t0, EXCEPTION_UNWIND, t0 // check if unwind in progress bne t0, 10f // if neq, unwind in progress
//// Unwind is not in progress - return nested exception disposition.//
//// Convert the given establisher virtual frame pointer (a1) to a real frame// pointer (the value of a1 minus CfFrameLength) and retrieve the pointer to// the dispatcher context that earlier was stored in the stack frame.//
ldq t0, -CfFrameLength + CfA3(a1) // get dispatcher context address
ldl t1, DcEstablisherFrame(t0) // copy the establisher frame pointer stl t1, DcEstablisherFrame(a3) // to current dispatcher context
ldil v0, ExceptionNestedException // set disposition value ret zero, (ra) // return
//// Unwind is in progress - return continue search disposition.//
10: ldil v0, ExceptionContinueSearch // set disposition value ret zero, (ra) // return
.end RtlpExceptionHandler SBTTL("Execute Handler for Unwind")//++//// EXCEPTION_DISPOSITION// RtlpExecuteHandlerForUnwind (// IN PEXCEPTION_RECORD ExceptionRecord,// IN PVOID EstablisherFrame,// IN OUT PCONTEXT ContextRecord,// IN OUT PVOID DispatcherContext,// IN PEXCEPTION_ROUTINE ExceptionRoutine// )//// Routine Description://// This function allocates a call frame, stores the establisher frame// pointer and the context record address in the frame, establishes an// exception handler, and then calls the specified exception handler as// an unwind handler. If a collided unwind occurs, then the exception// handler of this function is called and the establisher frame pointer// and context record address are returned to the unwind dispatcher via// the dispatcher context parameter. If control is returned to this routine,// then the frame is deallocated and the disposition status is returned to// the unwind dispatcher.//// Arguments://// ExceptionRecord (a0) - Supplies a pointer to an exception record.//// EstablisherFrame (a1) - Supplies the frame pointer of the establisher// of the exception handler that is to be called.//// ContextRecord (a2) - Supplies a pointer to a context record.//// DispatcherContext (a3) - Supplies a pointer to the dispatcher context// record.//// ExceptionRoutine (a4) - Supplies a pointer to the exception handler that// is to be called.//// Return Value://// The disposition value returned by the specified exception handler is// returned as the function value.////--
//// N.B. This function specifies its own private exception handler.//
EXCEPTION_HANDLER(RtlpUnwindHandler)
NESTED_ENTRY(RtlpExecuteHandlerForUnwind, CfFrameLength, zero)
lda sp, -CfFrameLength(sp) // allocate stack frame stq ra, CfRa(sp) // save return address
PROLOGUE_END
//// Save the address of the dispatcher context record in our stack frame so// that our own exception handler (not the one we're calling) can retrieve it.//
stq a3, CfA3(sp) // save address of dispatcher context
//// Now call the exception handler and return its return value as our return// value.//
bic a4, 3, a4 // clear low-order bits (IEEE mode) jsr ra, (a4) // call exception handler
ldq ra, CfRa(sp) // restore return address lda sp, CfFrameLength(sp) // deallocate stack frame ret zero, (ra) // return
.end RtlpExecuteHandlerForUnwind SBTTL("Local Unwind Handler")//++//// EXCEPTION_DISPOSITION// RtlpUnwindHandler (// IN PEXCEPTION_RECORD ExceptionRecord,// IN PVOID EstablisherFrame,// IN OUT PCONTEXT ContextRecord,// IN OUT PVOID DispatcherContext// )//// Routine Description://// This function is called when a collided unwind occurs. Its function// is to retrieve the establisher dispatcher context, copy it to the// current dispatcher context, and return a disposition value of nested// unwind.//// Arguments://// ExceptionRecord (a0) - Supplies a pointer to an exception record.//// EstablisherFrame (a1) - Supplies the frame pointer of the establisher// of this exception handler.//// ContextRecord (a2) - Supplies a pointer to a context record.//// DispatcherContext (a3) - Supplies a pointer to the dispatcher context// record.//// Return Value://// A disposition value ExceptionCollidedUnwind is returned if an unwind is// in progress. Otherwise, a value of ExceptionContinueSearch is returned.////--
LEAF_ENTRY(RtlpUnwindHandler)
ldl t0, ErExceptionFlags(a0) // get exception flags and t0, EXCEPTION_UNWIND, t0 // check if unwind in progress beq t0, 10f // if eq, unwind not in progress
//// Unwind is in progress - return collided unwind disposition.//
//// Convert the given establisher virtual frame pointer (a1) to a real frame// pointer (the value of a1 minus CfFrameLength) and retrieve the pointer to// the dispatcher context that earlier was stored in the stack frame.//
ldq t0, -CfFrameLength + CfA3(a1) // get dispatcher context address
ldl t1, DcControlPc(t0) // copy the entire dispatcher ldl t2, DcFunctionEntry(t0) // context of the establisher ldl t3, DcEstablisherFrame(t0) // frame... ldl t4, DcContextRecord(t0) //
stl t1, DcControlPc(a3) // to the current dispatcher stl t2, DcFunctionEntry(a3) // context (it's four words stl t3, DcEstablisherFrame(a3) // long). stl t4, DcContextRecord(a3) //
ldil v0, ExceptionCollidedUnwind // set disposition value ret zero, (ra) // return
//// Unwind is not in progress - return continue search disposition.//
10: ldil v0, ExceptionContinueSearch // set disposition value ret zero, (ra) // return
.end RtlpUnwindHandler SBTTL("Execute Exception Filter")//++//// ULONG// RtlpExecuteExceptionFilter (// PEXCEPTION_POINTERS ExceptionPointers,// EXCEPTION_FILTER ExceptionFilter,// ULONG EstablisherFrame// )//// Routine Description://// This function sets the static link and transfers control to the specified// exception filter routine.//// Arguments://// ExceptionPointers (a0) - Supplies a pointer to the exception pointers// structure.//// ExceptionFilter (a1) - Supplies the address of the exception filter// routine.//// EstablisherFrame (a2) - Supplies the establisher frame pointer.//// Return Value://// The value returned by the exception filter routine.////--
LEAF_ENTRY(RtlpExecuteExceptionFilter)
//// The protocol for calling exception filters used by the acc C-compiler is// that the uplevel frame pointer is passed in register v0 and the pointer// to the exception pointers structure is passed in register a0. The Gem// compiler expects the static link in t0. Here we do both.//
mov a2, v0 // set static link mov a2, t0 // set alternate static link jmp zero, (a1) // transfer control to exception filter
.end RtlpExecuteExceptionFilter SBTTL("Execute Termination Handler")//++//// VOID// RtlpExecuteTerminationHandler (// BOOLEAN AbnormalTermination,// TERMINATION_HANDLER TerminationHandler,// ULONG EstablisherFrame// )//// Routine Description://// This function sets the static link and transfers control to the specified// termination handler routine.//// Arguments://// AbnormalTermination (a0) - Supplies a boolean value that determines// whether the termination is abnormal.//// TerminationHandler (a1) - Supplies the address of the termination handler// routine.//// EstablisherFrame (a2) - Supplies the establisher frame pointer.//// Return Value://// None.////--
LEAF_ENTRY(RtlpExecuteTerminationHandler)
//// The protocol for calling termination handlers used by the acc C-compiler// is that the uplevel frame pointer is passed in register v0 and the boolean// abnormal termination value is passed in register a0. The Gem compiler// expects the static link in t0. Here we do both.//
mov a2, v0 // set static link mov a2, t0 // set alternate static link jmp zero, (a1) // transfer control to termination handler
.end RtlpExecuteTerminationHandler SBTTL("Get Stack Limits")//++//// VOID// RtlpGetStackLimits (// OUT PULONG LowLimit,// OUT PULONG HighLimit// )//// Routine Description://// This function returns the current stack limits based on the current// processor mode.//// Arguments://// LowLimit (a0) - Supplies a pointer to a variable that is to receive// the low limit of the stack.//// HighLimit (a1) - Supplies a pointer to a variable that is to receive// the high limit of the stack.//// Return Value://// None.////--
LEAF_ENTRY(RtlpGetStackLimits)#if defined(NTOS_KERNEL_RUNTIME)
//// Current mode is kernel - compute stack limits.//
GET_INITIAL_KERNEL_STACK // get initial kernel stack in v0
mov v0, t1 // copy high limit of kernel stack GET_CURRENT_THREAD // get current thread in v0 ldl t2, ThStackLimit(v0) // get low limit of kernel stack#else
//// Current mode is user - get stack limits from the TEB.//
GET_THREAD_ENVIRONMENT_BLOCK // get address of TEB in v0
ldl t1, TeStackBase(v0) // get high limit of user stack ldl t2, TeStackLimit(v0) // get low limit of user stack#endif
stl t2, 0(a0) // store low stack limit stl t1, 0(a1) // store high stack limit ret zero, (ra) // return
.end RtlpGetStackLimits
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