1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
|
#pragma once
/* DirectoryEntry
* |31| | | | | | | | | | | | | | | | | | | |11| | 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
* | page table 4-kb aligned address | avail | G| S| | A| C| W| U| R| P| */
struct __attribute__((packed)) DirectoryEntry {
unsigned present : 1; /* 0: if set, the page is actually in physical memory */
unsigned writeable : 1; /* 1: if set, the page is read/write; otherwise the page is read-only */
unsigned user : 1; /* 2: if set, then page can be access by all; otherwise only the supervisor can access it */
unsigned writethrough : 1; /* 3: if set, write-through caching is enabled; otherwise write-back is enabled instead */
unsigned cachedisable : 1; /* 4: if set, the page will not be cached */
unsigned accessed : 1; /* 5: set by the CPU when the page is read from or written to */
unsigned dirty : 1; /* 6: used to determine whether a page has been written to */
unsigned pagesize : 1; /* 7: page size == 0 */
unsigned global : 1;
unsigned int __available__ : 3; /* available to the OS */
unsigned int address : 20;
};
/* TODO _Static_assert(sizeof(struct DirectoryEntry) == 4, "DirectoryEntry size"); */
/* DirectoryEntry4MB
* |31| | | | | | | | |22|21|20| | | | | | |13|12|11| | 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
* | bits 31-22 of address |RS| bits 39-22 of |AT| avail | G|PS| D| A|CD|WT|US|RW| P|
* | |VD| address */
struct __attribute__((packed)) DirectoryEntry4MB {
unsigned present : 1; /* 0: if set, the page is actually in physical memory */
unsigned writeable : 1; /* 1: if set, the page is read/write; otherwise the page is read-only */
unsigned useraccess : 1; /* 2: if set, then page can be access by all; otherwise only the supervisor can access it */
unsigned writethrough : 1; /* 3: if set, write-through caching is enabled; otherwise write-back is enabled instead */
unsigned cachedisable : 1; /* 4: if set, the page will not be cached */
unsigned accessed : 1; /* 5: set by the CPU when the page is read from or written to */
unsigned dirty : 1; /* 6: used to determine whether a page has been written to */
unsigned pagesize : 1; /* 7: page size == 1 */
unsigned global : 1; /* 8: */
unsigned __available__ : 3; /* 11..9 available to the OS */
unsigned pat : 1; /* 12: page attribute table */
unsigned int address_high : 8;
unsigned rsvd : 1; /* 21 */
unsigned int address_low : 10;
};
/* TODO _Static_assert(sizeof(struct DirectoryEntry4MB) == 4, "DirectoryEntry4M size"); */
/* TableEntry
* |31| | | | | | | | | | | | | | | | | | | |11| | 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
* | page table 4-kb aligned address | avail | G| | D| A| C| W|US|RW| P| */
struct __attribute__((packed)) TableEntry {
unsigned present : 1; /* if set, the page is actually in physical memory */
unsigned writeable : 1; /* if set, the page is read/write; otherwise the page is read-only */
unsigned user : 1; /* if set, then page can be access by all; otherwise only the supervisor can access it */
unsigned writethrough : 1; /* if set, write-through caching is enabled; otherwise write-back is enabled instead */
unsigned cachedisable : 1; /* if set, the page will not be cached */
unsigned accessed : 1; /* set by the CPU when the page is read from or written to */
unsigned dirty : 1; /* used to determine whether a page has been written to */
unsigned pat : 1; /* page attribute table? */
unsigned global : 1;
unsigned int __available__ : 3; /* available to the OS */
unsigned int address : 20;
};
/* TODO _Static_assert(sizeof(struct TableEntry) == 4, "TableEntry size"); */
|
