// TITLE("Trampoline Code For User Mode APC and Exception Dispatching") // Copyright (c) 1990 Microsoft Corporation // Copyright (c) 1992 Digital Equipment Corporation // Module Name: // trampoln.s // Abstract: // This module implements the trampoline code necessary to dispatch user // mode APCs and exceptions. // Author: // David N. Cutler (davec) 3-Apr-1990 // Environment: // User mode only. // Revision History: // Thomas Van Baak (tvb) 11-May-1992 // Adapted for Alpha AXP. #include "ksalpha.h" // Define length of exception dispatcher stack frame. #define ExceptionDispatcherFrameLength (ExceptionRecordLength + ContextFrameLength) SBTTL("User APC Dispatcher") // The following code is never executed. Its purpose is to support unwinding // through the call to the APC dispatcher. // N.B. This function specifies its own private exception handler. EXCEPTION_HANDLER(KiUserApcHandler) NESTED_ENTRY(KiUserApcDispatch, ContextFrameLength, zero); .set noreorder .set noat stq sp, CxIntSp(sp) // save stack pointer stq ra, CxIntRa(sp) // save return address stq ra, CxFir(sp) // set continuation address stq fp, CxIntFp(sp) // save integer register fp stq gp, CxIntGp(sp) // save integer register gp stq s0, CxIntS0(sp) // save integer registers s0 - s5 stq s1, CxIntS1(sp) // stq s2, CxIntS2(sp) // stq s3, CxIntS3(sp) // stq s4, CxIntS4(sp) // stq s5, CxIntS5(sp) // stt f2, CxFltF2(sp) // save floating registers f2 - f9 stt f3, CxFltF3(sp) // stt f4, CxFltF4(sp) // stt f5, CxFltF5(sp) // stt f6, CxFltF6(sp) // stt f7, CxFltF7(sp) // stt f8, CxFltF8(sp) // stt f9, CxFltF9(sp) // mov sp, fp // set frame pointer .set at .set reorder PROLOGUE_END // VOID // KiUserApcDispatcher ( // IN PVOID NormalContext, // IN PVOID SystemArgument1, // IN PVOID SystemArgument2, // IN PKNORMAL_ROUTINE NormalRoutine // ) // Routine Description: // This routine is entered on return from kernel mode to deliver an APC // in user mode. The context frame for this routine was built when the // APC interrupt was processed and contains the entire machine state of // the current thread. The specified APC routine is called and then the // machine state is restored and execution is continued. // Arguments: // a0 - Supplies the normal context parameter that was specified when the // APC was initialized. // a1 - Supplies the first argument that was provided by the executive when // the APC was queued. // a2 - Supplies the second argument that was provided by the executive // when the APC was queued. // a3 - Supplies the address of the function that is to be called. // N.B. Register sp supplies a pointer to a context frame. // N.B. Register fp supplies the same value as sp and is used as a frame // pointer. // Return Value: // None. // N.B. This function is not called in the typical way. Instead of a normal // subroutine call to the nested entry point above, the alternate entry point // address below is stuffed into the Fir address of the trap frame. Thus when // the kernel returns from the trap, the following code is executed directly. ALTERNATE_ENTRY(KiUserApcDispatcher) jsr ra, (a3) // call specified APC routine mov fp, a0 // set address of context frame ldil a1, TRUE // set test alert argument true bsr ra, ZwContinue // execute system service to continue mov v0, s0 // save status value // Unsuccessful completion after attempting to continue execution. Use the // return status as the exception code, set noncontinuable exception and // attempt to raise another exception. Note there is no return from raise // status. 10: mov s0, a0 // set status value bsr ra, RtlRaiseStatus // raise exception br zero, 10b // loop on return .end KiUserApcDispatch SBTTL("User APC Exception Handler") // EXCEPTION_DISPOSITION // KiUserApcHandler ( // IN PEXCEPTION_RECORD ExceptionRecord, // IN UINT_PTR EstablisherFrame, // IN OUT PCONTEXT ContextRecord, // IN OUT PDISPATCHER_CONTEXT DispatcherContext // Routine Description: // This function is called when an exception occurs in an APC routine // or one of its dynamic descendents, or when an unwind through the // APC dispatcher is in progress. If an unwind is in progress, then test // alert is called to ensure that all currently queued APCs are executed. // 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: // ExceptionContinueSearch is returned as the function value. .struct 0 HdRa: .space 8 // saved return address .space 1 * 8 // required for 16-byte stack alignment HandlerFrameLength: // length of handler frame NESTED_ENTRY(KiUserApcHandler, HandlerFrameLength, zero) lda sp, -HandlerFrameLength(sp) // allocate stack frame stq ra, HdRa(sp) // save return address PROLOGUE_END // The following code is equivalent to: // EXCEPTION_DISPOSITION // KiUserApcHandler(IN PEXCEPTION_RECORD ExceptionRecord) // { // if (IS_UNWINDING(ExceptionRecord->ExceptionFlags)) { // NtTestAlert(); // } // return ExceptionContinueSearch // } ldl t0, ErExceptionFlags(a0) // get exception flags and t0, EXCEPTION_UNWIND, t0 // check if unwind in progress beq t0, 10f // if eq, no unwind in progress bsr ra, ZwTestAlert // test for alert pending 10: ldil v0, ExceptionContinueSearch // set disposition value ldq ra, HdRa(sp) // restore return address lda sp, HandlerFrameLength(sp) // deallocate stack frame ret zero, (ra) // return .end KiUserApcHandler SBTTL("User Callback Dispatcher") // The following code is never executed. Its purpose is to support unwinding // through the call to the exception dispatcher. NESTED_ENTRY(KiUserCallbackDispatch, ContextFrameLength, zero); .set noreorder stq sp, CkSp(sp) stq ra, CkRa(sp) .set reorder PROLOGUE_END // VOID // KiUserCallbackDispatcher ( // VOID // ) // Routine Description: // This routine is entered on a callout from kernel mode to execute a // user mode callback function. All arguments for this function have // been placed on the stack. // Arguments: // (sp + 16) - Supplies a value of zero for alignment. // (sp + 24) - Supplies the API number of the callback function that is // executed. // (sp + 32) - Supplies a pointer to the input buffer. // (sp + 40) - Supplies the input buffer length. // Return Value: // This function returns to kernel mode. ALTERNATE_ENTRY(KiUserCallbackDispatcher) LDP a0, CkBuffer(sp) // get input buffer address ldl a1, CkLength(sp) // get input buffer length ldl t0, CkApiNumber(sp) // get API number GET_THREAD_ENVIRONMENT_BLOCK // get TEB in v0 LDP t5, TePeb(v0) // get PEB in t5 LDP t2, PeKernelCallbackTable(t5) // get address of callback table SPADDP t0, t2, t3 // get address of callback LDP t4, 0(t3) // get callback pointer jsr ra, (t4) // call specified function // If a return from the callback function occurs, then the output buffer // address and length are returned as NULL. bis zero,zero,a0 // set zero buffer address bis zero,zero,a1 // set zero buffer length bis v0, zero, a2 // set completion status bsr ra, ZwCallbackReturn // return to kernel mode // Unsuccessful completion after attempting to return to kernel mode. Use // the return status as the exception code, set noncontinuable exception and // attempt to raise another exception. Note there is no return from raise // status. bis v0, zero, s0 // save status value 10: bis s0, zero, a0 // set status value bsr ra, RtlRaiseStatus // raise exception br zero, 10b // loop on return .end KiUserCallbackDispatch SBTTL("User Exception Dispatcher") // The following code is never executed. Its purpose is to support unwinding // through the call to the exception dispatcher. // When reverse executed, this prologue will restore all integer registers, // rather than just the non-volatile registers. This is necessary for proper // unwinding through the call to the exception dispatcher when non-standard // calls have been used in frames at or above the exception frame. Non-leaf // functions using a non-standard call are allowed to save the return address // register in another integer register instead of on the stack. NESTED_ENTRY(KiUserExceptionDispatch, ExceptionDispatcherFrameLength, zero); .set noreorder .set noat stq sp, CxIntSp(sp) // save stack pointer stq ra, CxIntRa(sp) // save return address stq ra, CxFir(sp) // set continuation address stq v0, CxIntV0(sp) // save integer register v0 stq t0, CxIntT0(sp) // save integer registers t0 - t6 stq t1, CxIntT1(sp) // stq t2, CxIntT2(sp) // stq t3, CxIntT3(sp) // stq t4, CxIntT4(sp) // stq t5, CxIntT5(sp) // stq t6, CxIntT6(sp) // stq t7, CxIntT7(sp) // stq s0, CxIntS0(sp) // save integer registers s0 - s5 stq s1, CxIntS1(sp) // stq s2, CxIntS2(sp) // stq s3, CxIntS3(sp) // stq s4, CxIntS4(sp) // stq s5, CxIntS5(sp) // stq fp, CxIntFp(sp) // save integer register fp stq a0, CxIntA0(sp) // save integer registers a0 - a5 stq a1, CxIntA1(sp) // stq a2, CxIntA2(sp) // stq a3, CxIntA3(sp) // stq a4, CxIntA4(sp) // stq a5, CxIntA5(sp) // stq t8, CxIntT8(sp) // save integer registers t8 - t11 stq t9, CxIntT9(sp) // stq t10, CxIntT10(sp) // stq t11, CxIntT11(sp) // stq t12, CxIntT12(sp) // save integer register t12 stq AT, CxIntAt(sp) // save integer register AT stq gp, CxIntGp(sp) // save integer register gp stt f2, CxFltF2(sp) // save floating registers f2 - f9 stt f3, CxFltF3(sp) // stt f4, CxFltF4(sp) // stt f5, CxFltF5(sp) // stt f6, CxFltF6(sp) // stt f7, CxFltF7(sp) // stt f8, CxFltF8(sp) // stt f9, CxFltF9(sp) // mov sp, fp // set frame pointer .set at .set reorder PROLOGUE_END // VOID // KiUserExceptionDispatcher ( // IN PEXCEPTION_RECORD ExceptionRecord, // IN PCONTEXT ContextRecord // ) // Routine Description: // This routine is entered on return from kernel mode to dispatch a user // mode exception. If a frame based handler handles the exception, then // the execution is continued. Otherwise last chance processing is performed. // Arguments: // s0 - Supplies a pointer to an exception record. // s1 - Supplies a pointer to a context frame. // fp - Supplies the same value as sp and is used as a frame pointer. // Return Value: // None. // N.B. This function is not called in the typical way. Instead of a normal // subroutine call to the nested entry point above, the alternate entry point // address below is stuffed into the Fir address of the trap frame. Thus when // the kernel returns from the trap, the following code is executed directly. ALTERNATE_ENTRY(KiUserExceptionDispatcher) #if defined(_AXP64_) // // Give WOW64 a chance to clean up before the exception is dispatched. // This must be done from assembly code as WOW64 may switch stacks. // ldq t0, Wow64PrepareForException beq t0, 5f jsr ra, (t0) // returns with a0 and a1 preserved 5: #endif mov s0, a0 // set address of exception record mov s1, a1 // set address of context frame bsr ra, RtlDispatchException // attempt to dispatch the exception // If the return status is TRUE, then the exception was handled and execution // should be continued with the NtContinue service in case the context was // changed. If the return status is FALSE, then the exception was not handled // and NtRaiseException is called to perform last chance exception processing. beq v0, 10f // if eq [false], perform last chance processing // Continue execution. mov s1, a0 // set address of context frame ldil a1, FALSE // set test alert argument false bsr ra, ZwContinue // execute system service to continue br zero, 20f // join common code // Last chance processing. 10: mov s0, a0 // set address of exception record mov s1, a1 // set address of context frame ldil a2, FALSE // set first chance argument false bsr ra, ZwRaiseException // perform last chance processing // Common code for unsuccessful completion of the continue or last chance // service. Use the return status (which is now in v0) as the exception code, // set noncontinuable exception and attempt to raise another exception. Note // the stack grows and eventually this loop will end. 20: lda sp, -ExceptionRecordLength(sp) // allocate exception record mov sp, a0 // get address of actual record stl v0, ErExceptionCode(a0) // set exception code ldil t0, EXCEPTION_NONCONTINUABLE // set noncontinuable flag stl t0, ErExceptionFlags(a0) // store exception flags STP s0, ErExceptionRecord(a0) // set associated exception record stl zero, ErNumberParameters(a0) // set number of parameters bsr ra, RtlRaiseException // raise exception br zero, 20b // loop on error .end KiUserExceptionDispatch // NTSTATUS // KiRaiseUserExceptionDispatcher ( // IN NTSTATUS ExceptionCode // ) // Routine Description: // This routine is entered on return from kernel mode to raise a user // mode exception. // Arguments: // v0 - Supplies the status code to be raised. // Return Value: // ExceptionCode // N.B. This function is not called in the typical way. Instead of a normal // subroutine call to the nested entry point above, the alternate entry point // address below is stuffed into the Fir address of the trap frame. Thus when // the kernel returns from the trap, the following code is executed directly. .struct 0 RaiseRa: .space 8 // saved return address RaiseV0: .space 8 // saved S0 RaiseExr: .space ExceptionRecordLength // exception record for RtlRaiseException RaiseFrameLength: // length of handler frame NESTED_ENTRY(KiRaiseUserExceptionDispatcher, RaiseFrameLength, zero) lda sp, -RaiseFrameLength(sp) // allocate stack frame stq ra, RaiseRa(sp) // save return address PROLOGUE_END stq v0, RaiseV0(sp) // save function return status stl v0, ErExceptionCode+RaiseExr(sp) // set exception code stl zero, ErExceptionFlags+RaiseExr(sp) // set exception flags STP zero, ErExceptionRecord+RaiseExr(sp) // set exception record STP ra, ErExceptionAddress+RaiseExr(sp) // set exception address stl zero, ErNumberParameters+RaiseExr(sp) lda a0, RaiseExr(sp) // set argument to RtlRaiseException bsr ra, RtlRaiseException // attempt to raise the exception ldq v0, RaiseV0(sp) // return status ldq ra, RaiseRa(sp) // restore ra lda sp, RaiseFrameLength(sp) // deallocate stack frame ret zero, (ra) // return .end KiRaiseUserExceptionDispatch