nt!MiInitializeSystemCache函数分析之PointerPte-＞u.List.NextEntry的由来

第一部分：
1: kd> dd 0xc0304200
c0304200  c10c0000 00000000 00000000 00000000
c0304210  00000000 00000000 00000000 00000000
c0304220  00000000 00000000 00000000 00000000
c0304230  00000000 00000000 00000000 00000000
c0304240  00000000 00000000 00000000 00000000
c0304250  00000000 00000000 00000000 00000000
c0304260  00000000 00000000 00000000 00000000
c0304270  00000000 00000000 00000000 00000000
1: kd> dd 0xc0304300
c0304300  c1100000 00000000 00000000 00000000
c0304310  00000000 00000000 00000000 00000000
c0304320  00000000 00000000 00000000 00000000
c0304330  00000000 00000000 00000000 00000000
c0304340  00000000 00000000 00000000 00000000
c0304350  00000000 00000000 00000000 00000000
c0304360  00000000 00000000 00000000 00000000
c0304370  00000000 00000000 00000000 00000000
1: kd> dd 0xc0304400
c0304400  c1140000 00000000 00000000 00000000
c0304410  00000000 00000000 00000000 00000000
c0304420  00000000 00000000 00000000 00000000
c0304430  00000000 00000000 00000000 00000000
c0304440  00000000 00000000 00000000 00000000

第二部分：
VOID
MiInitializeSystemCache (
    IN ULONG MinimumWorkingSet,
    IN ULONG MaximumWorkingSet
    )

    //
    // Build a free list structure in the PTEs for the system cache.
    //

    MmSystemCachePteBase = MI_PTE_BASE_FOR_LOWEST_KERNEL_ADDRESS;

    SizeOfSystemCacheInPages = MI_COMPUTE_PAGES_SPANNED (MmSystemCacheStart,
                                (PCHAR)MmSystemCacheEnd - (PCHAR)MmSystemCacheStart + 1);

    HunksOf256KInCache = SizeOfSystemCacheInPages / (X256K / PAGE_SIZE);

    PointerPte = MiGetPteAddress (MmSystemCacheStart);

    MmFirstFreeSystemCache = PointerPte;

    for (i = 0; i < HunksOf256KInCache; i += 1) {
        PointerPte->u.List.NextEntry = (PointerPte + (X256K / PAGE_SIZE)) - MmSystemCachePteBase;
        PointerPte += X256K / PAGE_SIZE;
    }

PointerPte->u.List.NextEntry = (PointerPte + (X256K / PAGE_SIZE)) - MmSystemCachePteBase;

(PointerPte + (X256K / PAGE_SIZE))表示指针，MmSystemCachePteBase表示指针
减完要除以4，表示个数，右移2位

第三部分：

#define PAGE_SIZE                   0x1000
#define X256K 0x40000

1: kd> ?0x40000/0x1000
Evaluate expression: 64 = 00000040

0100 0000
0100 0000 00
01    00 00    00 00    =    0x100

0xc0304000+0x100=0xc0304100
0xc0304100-0xc0000000=0x304100

304100

0011 00    00     0100     0001     0000 0000
11 00    00     0100     0001     0000 00
11 00    00     01    00     00    01     00    00 00
c1040

      +0x000 List             : _MMPTE_LIST
         +0x000 Valid            : Pos 0, 1 Bit
         +0x000 OneEntry         : Pos 1, 1 Bit
         +0x000 filler0          : Pos 2, 8 Bits
         +0x000 Prototype        : Pos 10, 1 Bit
         +0x000 filler1          : Pos 11, 1 Bit
         +0x000 NextEntry        : Pos 12, 20 Bits

1: kd> x nt!MmSystemCachePteBase
80b2358c          nt!MmSystemCachePteBase = 0xc0000000

1: kd> dd 0xc0304000
c0304000  c1040000

第四部分：

0xc0304200

0xc0304300

304300
0011 0000 0100 0011 0000 0000

11 0000 0100 0011 0000 0000 00

11 00    00 01    00 00    11 00    00 00    00 00
c10c0

1: kd> dd 0xc0304200
c0304200  c10c0000 00000000 00000000 00000000
c0304210  00000000 00000000 00000000 00000000
c0304220  00000000 00000000 00000000 00000000
c0304230  00000000 00000000 00000000 00000000
c0304240  00000000 00000000 00000000 00000000
c0304250  00000000 00000000 00000000 00000000
c0304260  00000000 00000000 00000000 00000000
c0304270  00000000 00000000 00000000 00000000
1: kd> dd 0xc0304300
c0304300  c1100000 00000000 00000000 00000000
c0304310  00000000 00000000 00000000 00000000
c0304320  00000000 00000000 00000000 00000000
c0304330  00000000 00000000 00000000 00000000
c0304340  00000000 00000000 00000000 00000000
c0304350  00000000 00000000 00000000 00000000
c0304360  00000000 00000000 00000000 00000000
c0304370  00000000 00000000 00000000 00000000
1: kd> dd 0xc0304400
c0304400  c1140000 00000000 00000000 00000000
c0304410  00000000 00000000 00000000 00000000
c0304420  00000000 00000000 00000000 00000000
c0304430  00000000 00000000 00000000 00000000
c0304440  00000000 00000000 00000000 00000000

第五部分：F:\srv03rtm\base\ntos/mm/mapcache.c:39:PMMPTE MmSystemCachePteBase;

MmSystemCachePteBase类型是指针，+1相当于+4，向左移两位。

    PointerPte = MmFirstFreeSystemCache;            0xc0304000

    //
    // Update next free entry.
    //

    ASSERT (PointerPte->u.Hard.Valid == 0);

    MmFirstFreeSystemCache = MmSystemCachePteBase + PointerPte->u.List.NextEntry;
    ASSERT (MmFirstFreeSystemCache <= MiGetPteAddress (MmSystemCacheEnd));

0xc1040+0xc0000000=0xc00c1040

1: kd> dd 0xc0304000
c0304000  c1040000

      +0x000 List             : _MMPTE_LIST
         +0x000 Valid            : Pos 0, 1 Bit
         +0x000 OneEntry         : Pos 1, 1 Bit
         +0x000 filler0          : Pos 2, 8 Bits
         +0x000 Prototype        : Pos 10, 1 Bit
         +0x000 filler1          : Pos 11, 1 Bit
         +0x000 NextEntry        : Pos 12, 20 Bits

c1040
1100 0001 0000 0100 0000  
11    00 00    01 00    00 01    00 00    00 00

304100
c0304100