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192 lines
3.7 KiB
192 lines
3.7 KiB
//+-----------------------------------------------------------------------
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//
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// Microsoft Windows
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//
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// Copyright (c) Microsoft Corporation 1991 - 1992
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//
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// File: memmgr.c
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//
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// Contents: Fast memory manager code for KSecDD
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//
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//
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// History: 23 Feb 93 RichardW Created
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//
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//------------------------------------------------------------------------
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#include <sspdrv.h>
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KSPIN_LOCK ResourceSpinLock; // Spin Lock guard for resource lists
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PKernelContext pFreeContexts; // Free context records
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ULONG cFreeContexts; // Count of free context records
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#define MAX_FREE_CONTEXTS 20 // max number of entries on the free
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// context list.
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// Debugging statistics.
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//
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// These track the number of various records in use
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// or allocated from the system.
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#if DBG
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ULONG cTotalCtxtRecs;
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ULONG cActiveCtxtRecs;
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#endif
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(INIT, KsecInitMemory)
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#endif
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//+-------------------------------------------------------------------------
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//
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// Function: KsecInitMemory
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//
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// Synopsis: Initializes free lists and spin lock
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//
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// Effects:
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//
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// Arguments:
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//
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// Requires:
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//
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// Returns:
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//
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// Notes:
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//
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//--------------------------------------------------------------------------
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BOOLEAN
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KsecInitMemory(void)
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{
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KeInitializeSpinLock(&ResourceSpinLock);
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pFreeContexts = NULL;
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#if DBG
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cActiveCtxtRecs = 0;
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cTotalCtxtRecs = 0;
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#endif
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return(TRUE);
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}
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//+-------------------------------------------------------------------------
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//
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// Function: AllocContextRec
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//
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// Synopsis: Allocates a KernelContext structure
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//
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// Effects:
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//
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// Arguments:
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//
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// Requires:
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//
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// Returns:
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//
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// Notes:
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//
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//--------------------------------------------------------------------------
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PKernelContext
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AllocContextRec(void)
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{
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PKernelContext pContext = NULL;
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KIRQL OldIrql;
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KeAcquireSpinLock(&ResourceSpinLock, &OldIrql);
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if (pFreeContexts)
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{
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pContext = pFreeContexts;
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pFreeContexts = pFreeContexts->pNext;
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ASSERT(cFreeContexts != 0);
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cFreeContexts--;
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}
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KeReleaseSpinLock(&ResourceSpinLock, OldIrql);
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if (pContext == NULL)
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{
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pContext = (PKernelContext)
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ExAllocatePool(NonPagedPool, sizeof(KernelContext));
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DebugStmt(cTotalCtxtRecs++);
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}
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if (pContext == NULL)
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{
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DebugLog((DEB_ERROR,"Could not allocate from pool!\n"));
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return(NULL);
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}
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pContext->pNext = NULL;
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pContext->pPrev = NULL;
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DebugStmt(cActiveCtxtRecs++);
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return(pContext);
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}
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//+-------------------------------------------------------------------------
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//
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// Function: FreeContextRec
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//
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// Synopsis: Returns a KernelContext record to the free list
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//
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// Effects:
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//
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// Arguments:
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//
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// Requires:
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//
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// Returns:
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//
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// Notes:
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//
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//--------------------------------------------------------------------------
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void
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FreeContextRec(PKernelContext pContext)
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{
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KIRQL OldIrql;
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KeAcquireSpinLock(&ResourceSpinLock, &OldIrql);
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//
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// If we haven't reached the threshold for our free list, return
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// this to the free list.
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//
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if (cFreeContexts < MAX_FREE_CONTEXTS)
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{
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pContext->pNext = pFreeContexts;
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pFreeContexts = pContext;
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cFreeContexts++;
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KeReleaseSpinLock(&ResourceSpinLock, OldIrql);
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}
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else
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{
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//
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// Release our lock, to avoid deadlocks, and
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// just return the context to the pool.
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//
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KeReleaseSpinLock(&ResourceSpinLock, OldIrql);
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ExFreePool(pContext);
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}
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DebugStmt(cActiveCtxtRecs--);
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}
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