Source code of Windows XP (NT5)
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// TITLE("Asynchronous Procedure Call (APC) Interrupt")
//++
//
// Copyright (c) 1990 Microsoft Corporation
//
// Module Name:
//
// apcint.s
//
// Abstract:
//
// This module implements the code necessary to field and process the
// Asynchronous Procedure Call (APC) interrupt.
//
// Author:
//
// David N. Cutler (davec) 3-Apr-1990
// Joe Notarangelo 15-Jul-1992 alpha version
//
// Environment:
//
// Kernel mode only, IRQL APC_LEVEL.
//
// Revision History:
//
//--
#include "ksalpha.h"
SBTTL("Asynchronous Procedure Call Interrupt")
//++
//
// Routine Description:
//
// This routine is entered as the result of a software interrupt generated
// at APC_LEVEL. Its function is to allocate an exception frame and call
// the kernel APC delivery routine to deliver kernel mode APCs and to check
// if a user mode APC should be delivered. If a user mode APC should be
// delivered, then the kernel APC delivery routine constructs a context
// frame on the user stack and alters the exception and trap frames so that
// control will be transfered to the user APC dispatcher on return from the
// interrupt.
//
// N.B. On entry to this routine only the volatile integer registers have
// been saved. The remainder of the machine state is saved if and only
// if the previous mode was user mode. It is assumed that none of the
// APC delivery code, nor any of the kernel mode APC routines themselves
// use any floating point instructions.
//
// Arguments:
//
// s6/fp - Supplies a pointer to a trap frame.
//
// Return Value:
//
// None.
//
//--
NESTED_ENTRY(KiApcInterrupt, ExceptionFrameLength, zero)
lda sp, -ExceptionFrameLength(sp) // allocate exception frame
stq ra, ExIntRa(sp) // save return address
PROLOGUE_END
//
// Save the volatile floating state and determine the previous mode.
//
bsr ra, KiSaveVolatileFloatState // save volatile floats
ldl t0, TrPsr(fp) // get saved processor status
and t0, PSR_MODE_MASK, a0 // isolate previous mode
beq a0, 10f // if eq, kernel mode
//
// The previous mode was user.
//
// Save the nonvolatile machine state so a context record can be
// properly constructed to deliver an APC to user mode if required.
// It is also necessary to save the volatile floating state for
// suspend/resume operations.
//
stq s0, ExIntS0(sp) // save nonvolatile integer state
stq s1, ExIntS1(sp) //
stq s2, ExIntS2(sp) //
stq s3, ExIntS3(sp) //
stq s4, ExIntS4(sp) //
stq s5, ExIntS5(sp) //
bsr ra, KiSaveNonVolatileFloatState // save floating state
//
// Attempt to deliver an APC.
//
10: bis sp, zero, a1 // set address of exception frame
bis fp, zero, a2 // set address of trap frame
bsr ra, KiDeliverApc // call APC delivery routine
//
// Restore the volatile floating state and return from the interrupt.
//
bsr ra, KiRestoreVolatileFloatState // restore floating state
ldq ra, ExIntRa(sp) // restore return address
lda sp, ExceptionFrameLength(sp) // deallocate exception frame
ret zero, (ra) // return
.end KiApcInterrupt