virtmem.c

可用于嵌入式编程学习

    if (!pmbiBuffer || !lpvAddress || (ulong)lpvAddress>>VA_SECTION > SECTION_MASK)
        goto invalidParm;
    pscn = SectionTable[((ulong)lpvAddress>>VA_SECTION) & SECTION_MASK];
    if (pscn == NULL_SECTION)
        goto invalidParm;
    ixPage = ((ulong)lpvAddress >> VA_PAGE) & PAGE_MASK;
    ixBlock = ((ulong)lpvAddress >> VA_BLOCK) & BLOCK_MASK;
    if ((pmb = (*pscn)[ixBlock]) == NULL_BLOCK ||
        (pmb != RESERVED_BLOCK && pmb->aPages[ixPage] == BAD_PAGE) ||
        (ixFirB = FindFirstBlock(pscn, ixBlock)) == UNKNOWN_BASE) {
        /* The given page is in a free region, walk the section to compute
         * the size of the region */
        cPages = PAGES_PER_BLOCK - ixPage;
        while (++ixBlock < BLOCK_MASK+1 && (*pscn)[ixBlock] == NULL_BLOCK)
            cPages += PAGES_PER_BLOCK;
        pmbiBuffer->AllocationBase = 0;
        pmbiBuffer->State = MEM_FREE;
        pmbiBuffer->AllocationProtect = PAGE_NOACCESS;
        pmbiBuffer->Protect = PAGE_NOACCESS;
        pmbiBuffer->Type = 0;
    } else {
        cPages = 0;
        pmbiBuffer->AllocationProtect = PAGE_NOACCESS;
        pmbiBuffer->Type = MEM_PRIVATE;
        if (pmb == RESERVED_BLOCK || pmb->aPages[ixPage] == 0) {
            /* Count reserved pages */
            pmbiBuffer->State = MEM_RESERVE;
            pmbiBuffer->Protect = PAGE_NOACCESS;
            do {
                if (pmb == RESERVED_BLOCK)
                    cPages += PAGES_PER_BLOCK - ixPage;
                else {
                    pmbiBuffer->Type = AllocationType[pmb->flags & MB_FLAG_PAGER_TYPE];
                    do {
                        if (pmb->aPages[ixPage] != 0)
                            goto allCounted;
                        ++cPages;
                    } while (++ixPage < PAGES_PER_BLOCK);
                }
                ixPage = 0;
            } while (++ixBlock < BLOCK_MASK+1 &&
                     ((pmb = (*pscn)[ixBlock]) == RESERVED_BLOCK ||
                      (pmb != NULL_BLOCK && pmb->ixBase == ixFirB)));
        } else {
            /* Count committed pages */
            pmbiBuffer->State = MEM_COMMIT;
            ulPgPerm = pmb->aPages[ixPage] & PG_PERMISSION_MASK;
            pmbiBuffer->Protect = ProtectFromPerms(pmb->aPages[ixPage]);
            pmbiBuffer->Type = AllocationType[pmb->flags & MB_FLAG_PAGER_TYPE];
            do {
                do {
                    ulong ulPgInfo = pmb->aPages[ixPage];
                    if (ulPgInfo == 0 || ulPgInfo == BAD_PAGE
                            || (ulPgInfo&PG_PERMISSION_MASK) != ulPgPerm)
                        goto allCounted;
                    ++cPages;
                } while (++ixPage < PAGES_PER_BLOCK);
                ixPage = 0;
            } while (++ixBlock < BLOCK_MASK+1 &&
                     (pmb = (*pscn)[ixBlock]) != NULL_BLOCK &&
                     pmb != RESERVED_BLOCK && pmb->ixBase == ixFirB);
        }
allCounted:
        pmbiBuffer->AllocationBase =
                    (LPVOID)(((ulong)lpvAddress&(SECTION_MASK<<VA_SECTION)) |
                    		 ((ulong)ixFirB << VA_BLOCK));
    }
    pmbiBuffer->RegionSize = (DWORD)cPages << VA_PAGE;
    pmbiBuffer->BaseAddress = (LPVOID)((ulong)lpvAddress & ~(PAGE_SIZE-1));
    return sizeof(MEMORY_BASIC_INFORMATION);
invalidParm:
    DEBUGMSG(ZONE_VIRTMEM, (TEXT("VirtualQuery failed.\r\n")));
    KSetLastError(pCurThread, ERROR_INVALID_PARAMETER);
    return 0;
}

BOOL DoLockPages(
LPCVOID lpvAddress,      /* address of region of committed pages */
DWORD cbSize,           /* size of the region */
PDWORD pPFNs,           /* address of array to receive real PFN's */
int fOptions)           /* options: see LOCKFLAG_* in kernel.h */
{
    int ixBlock;
    int ixPage;
    int ixFirB;         /* index of first block in region */
    int ixStart;        /* index of start block of lock region */
    PSECTION pscn;
    int cPages;         /* # of pages to adjust */
    ulong ulBase;       /* base virtual address */
    MEMBLOCK *pmb;
    int err = ERROR_INVALID_PARAMETER;
    DEBUGMSG(ZONE_VIRTMEM, (TEXT("LockPages @%8.8lx size=%lx pPFNs=%lx options=%x\r\n"),
            lpvAddress, cbSize, pPFNs, fOptions));
    /* Verify that the requested region is within range and within an
     * existing reserved memory region that the client is allowed to
     * access and locate the starting block of the region.
     */
    if ((ulong)lpvAddress>>VA_SECTION > SECTION_MASK)
    	return TRUE;
    /* Lockout other changes to the virtual memory state. */
    EnterCriticalSection(&VAcs);
    if (!cbSize || !lpvAddress)
        goto invalidParm;
    ulBase = (ulong)lpvAddress & (SECTION_MASK << VA_SECTION);
    pscn = SectionTable[ulBase>>VA_SECTION];
    if (pscn == NULL_SECTION)
        goto invalidParm;
    ixBlock = ((ulong)lpvAddress >> VA_BLOCK) & BLOCK_MASK;
    if ((ixFirB = FindFirstBlock(pscn, ixBlock)) == UNKNOWN_BASE)
        goto invalidParm;
    /* Verify that all of the pages within the specified range belong to the
     * same VirtualAlloc region and are committed.
     *
     *  (pscn) = ptr to section array
     *  (ixBlock) = index of block containing the first page of lpvAddress
     *  (ixFirB) = index of first block in the region
     */
    ixPage = ((ulong)lpvAddress >> VA_PAGE) & PAGE_MASK;
    cPages = (((ulong)lpvAddress + cbSize + PAGE_SIZE-1) / PAGE_SIZE) - ((ulong)lpvAddress / PAGE_SIZE);
    if (ScanRegion(pscn, ixFirB, ixBlock, ixPage, cPages, 0) == -1)
        goto invalidParm;
    /* Walk the page tables to check that all pages are present and to
     * increment the lock count for each MEMBLOCK in the region.
     */
    ixStart = ixBlock;
    for (; cPages ; ++ixBlock) {
        pmb = (*pscn)[ixBlock];
        if (!(fOptions & LOCKFLAG_QUERY_ONLY)) {
            ++pmb->cLocks;
            DEBUGMSG(ZONE_VIRTMEM, (TEXT("Locking pages @%8.8x LC=%d\r\n"), 
                    ulBase | (ixBlock<<VA_BLOCK), pmb->cLocks));
        }
        do {
	        ulong addr = ulBase | (ixBlock<<VA_BLOCK) | (ixPage<<VA_PAGE);
            DEBUGCHK(pmb->aPages[ixPage] != BAD_PAGE);
            if (pmb->aPages[ixPage] == 0) {
                if (pmb->flags&MB_FLAG_AUTOCOMMIT) {
                    if (SC_VirtualAlloc((void*)addr, cPages*PAGE_SIZE, MEM_COMMIT,
                            PAGE_READWRITE) == 0)
                        goto cleanUpLocks;
                } else {
                	BOOL bRet;
                	LeaveCriticalSection(&VAcs);
                	bRet = ProcessPageFault(TRUE, addr);
                	if (!bRet && !(fOptions & LOCKFLAG_WRITE))
	                	bRet = ProcessPageFault(FALSE, addr);
                	EnterCriticalSection(&VAcs);
                	if (!bRet) {
                		err = ERROR_NOACCESS;
                    	goto cleanUpLocks;
                    }
                }
            } else {
                if (fOptions & LOCKFLAG_WRITE) {
                	if (!IsPageWritable(pmb->aPages[ixPage])) {
	                	BOOL bRet;
	                	LeaveCriticalSection(&VAcs);
	                	bRet = ProcessPageFault(TRUE, addr);
	                	EnterCriticalSection(&VAcs);
	                	if (!bRet) {
	                		err = ERROR_NOACCESS;
	                    	goto cleanUpLocks;
	                    }
	                }
                } else if (!IsPageReadable(pmb->aPages[ixPage])) {
                    err = ERROR_NOACCESS;
                    goto cleanUpLocks;
                }
                if ((fOptions & LOCKFLAG_READ) && !IsPageReadable(pmb->aPages[ixPage])) {
                    err = ERROR_NOACCESS;
	                goto cleanUpLocks;
                }
            }
            if (pPFNs)
   	            *pPFNs++ = PFNfromEntry(pmb->aPages[ixPage]);
        } while (--cPages && ++ixPage < PAGES_PER_BLOCK);
        ixPage = 0;            /* start with first page of next block */
    }
    LeaveCriticalSection(&VAcs);
    return TRUE;
cleanUpLocks:
    /* Unable to page in a page or this thread doesn't have the desired access
     * to a page in the range. Back out any locks which have been set.
     */
    if (!(fOptions & LOCKFLAG_QUERY_ONLY)) {
        do {
            --pmb->cLocks;
            DEBUGMSG(ZONE_VIRTMEM, (TEXT("Restoring lock count @%8.8x LC=%d\r\n"), 
                    ulBase | (ixBlock<<VA_BLOCK), pmb->cLocks));
        } while (ixBlock != ixStart && (pmb = (*pscn)[--ixBlock]));
    }
invalidParm:
    LeaveCriticalSection(&VAcs);
    DEBUGMSG(ZONE_VIRTMEM, (TEXT("LockPages failed.\r\n")));
    KSetLastError(pCurThread, err);
    return FALSE;
}

BOOL SC_LockPages(LPVOID lpvAddress, DWORD cbSize, PDWORD pPFNs, int fOptions) {
	if (pCurProc->bTrustLevel != KERN_TRUST_FULL) {
		ERRORMSG(1,(L"SC_LockPages failed due to insufficient trust\r\n"));
	    KSetLastError(pCurThread, ERROR_ACCESS_DENIED);
    	return 0;
	}
	return DoLockPages(lpvAddress, cbSize, pPFNs, fOptions);
}

BOOL DoUnlockPages(
LPCVOID lpvAddress,      /* address of region of committed pages */
DWORD cbSize)           /* size of the region */
{
    int ixPage;
    int ixBlock;
    int ixFirB;         /* index of first block in region */
    int ixLastBlock;    /* last block to be unlocked */
    PSECTION pscn;
    int cPages;         /* # of pages to adjust */
    MEMBLOCK *pmb;
    DEBUGMSG(ZONE_VIRTMEM, (TEXT("UnlockPages @%8.8lx size=%lx\r\n"),
            lpvAddress, cbSize));
    /* Verify that the requested region is within range and within an
     * existing reserved memory region that the client is allowed to
     * access and locate the starting block of the region.
     */
    /* Lockout other changes to the virtual memory state. */
    if ((ulong)lpvAddress>>VA_SECTION > SECTION_MASK)
    	return TRUE;
    EnterCriticalSection(&VAcs);
    if (!cbSize || !lpvAddress)
        goto invalidParm;
    pscn = SectionTable[((ulong)lpvAddress>>VA_SECTION) & SECTION_MASK];
    if (pscn == NULL_SECTION)
        goto invalidParm;
    ixBlock = ((ulong)lpvAddress >> VA_BLOCK) & BLOCK_MASK;
    if ((ixFirB = FindFirstBlock(pscn, ixBlock)) == UNKNOWN_BASE)
        goto invalidParm;
    /* Verify that all of the pages within the specified range belong to the
     * same VirtualAlloc region and are committed.
     *
     *  (pscn) = ptr to section array
     *  (ixBlock) = index of block containing the first page of lpvAddress
     *  (ixFirB) = index of first block in the region
     */
    ixPage = ((ulong)lpvAddress >> VA_PAGE) & PAGE_MASK;
    cPages = (((ulong)lpvAddress + cbSize + PAGE_SIZE-1) / PAGE_SIZE)
            - ((ulong)lpvAddress / PAGE_SIZE);
    if (ScanRegion(pscn, ixFirB, ixBlock, ixPage, cPages, 0) == -1)
        goto invalidParm;
    /* Walk the page tables to decrement the lock count for 
     * each MEMBLOCK in the region.
     */
    ixLastBlock = ixBlock + ((ixPage+cPages+PAGES_PER_BLOCK-1) >> (VA_BLOCK-VA_PAGE));
    for (; ixBlock < ixLastBlock ; ++ixBlock) {
        pmb = (*pscn)[ixBlock];
        if (pmb->cLocks)
            --pmb->cLocks;
        else
            DEBUGCHK(0);
        DEBUGMSG(ZONE_VIRTMEM, (TEXT("Unlocking pages @%8.8x LC=%d\r\n"), 
                ((ulong)lpvAddress&(SECTION_MASK<<VA_SECTION)) | (ixBlock<<VA_BLOCK),
                pmb->cLocks));
    }
    LeaveCriticalSection(&VAcs);
    return TRUE;
invalidParm:
    LeaveCriticalSection(&VAcs);
    DEBUGMSG(ZONE_VIRTMEM, (TEXT("LockPages failed.\r\n")));
    KSetLastError(pCurThread, ERROR_INVALID_PARAMETER);
    return FALSE;
}

BOOL SC_UnlockPages(LPVOID lpvAddress, DWORD cbSize) {
	if (pCurProc->bTrustLevel != KERN_TRUST_FULL) {
		ERRORMSG(1,(L"SC_UnlockPages failed due to insufficient trust\r\n"));
	    KSetLastError(pCurThread, ERROR_ACCESS_DENIED);
    	return 0;
	}
	return DoUnlockPages(lpvAddress, cbSize);
}

LPBYTE GrabFirstPhysPage(DWORD dwCount);

/* AutoCommit - auto-commit a page
 *
 *	This function is called for a TLB miss due to a memory load or store.
 *  It is invoked from the general exception handler on the kernel stack.
 *  If the faulting page, is within an auto-commit region then a new page
 *  will be allocated and committed.
 */
BOOL AutoCommit(ulong addr) {
	register MEMBLOCK *pmb;
	PSECTION pscn;
	int ixSect, ixBlock, ixPage;
	ulong ulPFN;
	LPBYTE pMem;
	DWORD loop;
	ixPage = addr>>VA_PAGE & PAGE_MASK;
	ixBlock = addr>>VA_BLOCK & BLOCK_MASK;
	ixSect = addr>>VA_SECTION;
	if ((ixSect <= SECTION_MASK) && ((pscn = SectionTable[ixSect]) != NULL_SECTION) &&
		((pmb = (*pscn)[ixBlock]) != NULL_BLOCK) && (pmb != RESERVED_BLOCK) &&
		(pmb->flags&MB_FLAG_AUTOCOMMIT) && !pmb->aPages[ixPage]) {
		for (loop = 0; loop < 20; loop++) {
			//
			// Notify OOM thread if we're low on memory.
			//
			if (GwesOOMEvent && (PageFreeCount < GwesCriticalThreshold)) {
				SetEvent(GwesOOMEvent);
			}
			//
			// We don't want to let AutoCommit deplete all physical memory. 
			// Yes, the thread needing the memory committed is going to fault
			// unexpectedly if we can't allocate, so we'll loop for 2 seconds
			// checking for available RAM. We need to reserve a small amount
			// so that DemandCommit can allocate stack for the