Source code of Windows XP (NT5)
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/*++
Copyright (c) 1992-2001 Microsoft Corporation
Module Name:
kdlock.c
Abstract:
This module contains code to synchronize the usage of the port
used by the kernel debugger.
Author:
Bryan M. Willman (bryanwi) 24-Sep-90
Revision History:
--*/
#include "kdp.h"
VOID
KdpPortLock(
VOID
)
/*++
Routine Description:
Acquire the spinlock for the debug port.
Note that user must call this explicitly, the get/put routines
do NOT make any use of the lock.
CALLER MUST HAVE SET PROPER IRQL BEFORE CALLING US.
We use KiAcquireSpinLock and NOT Ke... because our IRQL may
be above DISPATCH_LEVEL.
Arguments:
None.
Return value:
None.
--*/
{
KiAcquireSpinLock(&KdpDebuggerLock);
}
VOID
KdpPortUnlock(
VOID
)
/*++
Routine Description:
Release the spinlock for the debug port.
Note that user must call this explicitly, the get/put routines
do NOT make any use of the lock.
CALLER MUST HAVE SET PROPER IRQL BEFORE CALLING US.
We use KiReleaseSpinLock and NOT Ke... because our IRQL may
be above DISPATCH_LEVEL.
Arguments:
None.
Return value:
None.
--*/
{
KiReleaseSpinLock(&KdpDebuggerLock);
}
BOOLEAN
KdPollBreakIn(
VOID
)
/*++
Routine Description:
This procedure raises IRQL to high_level, seizes the Debug port
spinlock, and checks to see if a breakin packet is pending.
If a packet is present, return TRUE, else FALSE.
A packet is present if:
There is a valid character which matches BREAK_CHAR.
N.B. Interrupts must be OFF around this call
Return Value:
TRUE if breakin sequence present, caller should execute int-3.
FALSE if no breakin seen.
--*/
{
BOOLEAN BreakIn;
BOOLEAN Enable;
KIRQL OldIrql;
ULONG Status;
//
// If the debugger is enabled, see if a breakin by the kernel
// debugger is pending.
//
BreakIn = FALSE;
if (KdDebuggerEnabled != FALSE) {
Enable = KeDisableInterrupts();
#ifndef _X86_
KeRaiseIrql(HIGH_LEVEL, &OldIrql);
#endif
if (KdpContext.KdpControlCPending != FALSE) {
KdpControlCPressed = TRUE;
BreakIn = TRUE;
KdpContext.KdpControlCPending = FALSE;
} else {
if (KeTryToAcquireSpinLockAtDpcLevel(&KdpDebuggerLock) != FALSE) {
Status = KdReceivePacket(PACKET_TYPE_KD_POLL_BREAKIN,
NULL,
NULL,
NULL,
NULL);
if (Status == KDP_PACKET_RECEIVED) {
BreakIn = TRUE;
KdpControlCPressed = TRUE;
}
KdpPortUnlock();
}
}
#ifndef _X86_
KeLowerIrql(OldIrql);
#endif
KeEnableInterrupts(Enable);
}
return BreakIn;
}
BOOLEAN
KdpPollBreakInWithPortLock(
VOID
)
/*++
Routine Description:
This procedure same as KdPollBreakIn, but assumes the caller
already holds the port lock. Returns TRUE if a breakin packet
is pending.
A packet is present if:
There is a valid character which matches BREAK_CHAR.
N.B. Interrupts must be OFF around this call
Return Value:
TRUE if breakin sequence present, caller should execute int-3.
FALSE if no breakin seen.
--*/
{
BOOLEAN BreakIn;
BOOLEAN Enable;
ULONG Status;
//
// If the debugger is enabled, see if a breakin by the kernel
// debugger is pending.
//
BreakIn = FALSE;
if (KdDebuggerEnabled != FALSE) {
if (KdpContext.KdpControlCPending != FALSE) {
BreakIn = TRUE;
KdpContext.KdpControlCPending = FALSE;
} else {
Status = KdReceivePacket(PACKET_TYPE_KD_POLL_BREAKIN,
NULL,
NULL,
NULL,
NULL);
if (Status == KDP_PACKET_RECEIVED) {
BreakIn = TRUE;
}
}
}
return BreakIn;
}