1 #ifndef _ASM_POWERPC_NOHASH_32_PTE_44x_H
2 #define _ASM_POWERPC_NOHASH_32_PTE_44x_H
3 #ifdef __KERNEL__
4 
5 /*
6  * Definitions for PPC440
7  *
8  * Because of the 3 word TLB entries to support 36-bit addressing,
9  * the attribute are difficult to map in such a fashion that they
10  * are easily loaded during exception processing.  I decided to
11  * organize the entry so the ERPN is the only portion in the
12  * upper word of the PTE and the attribute bits below are packed
13  * in as sensibly as they can be in the area below a 4KB page size
14  * oriented RPN.  This at least makes it easy to load the RPN and
15  * ERPN fields in the TLB. -Matt
16  *
17  * This isn't entirely true anymore, at least some bits are now
18  * easier to move into the TLB from the PTE. -BenH.
19  *
20  * Note that these bits preclude future use of a page size
21  * less than 4KB.
22  *
23  *
24  * PPC 440 core has following TLB attribute fields;
25  *
26  *   TLB1:
27  *   0  1  2  3  4  ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
28  *   RPN.................................  -  -  -  -  -  - ERPN.......
29  *
30  *   TLB2:
31  *   0  1  2  3  4  ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
32  *   -  -  -  -  -    - U0 U1 U2 U3 W  I  M  G  E   - UX UW UR SX SW SR
33  *
34  * Newer 440 cores (440x6 as used on AMCC 460EX/460GT) have additional
35  * TLB2 storage attibute fields. Those are:
36  *
37  *   TLB2:
38  *   0...10    11   12   13   14   15   16...31
39  *   no change WL1  IL1I IL1D IL2I IL2D no change
40  *
41  * There are some constrains and options, to decide mapping software bits
42  * into TLB entry.
43  *
44  *   - PRESENT *must* be in the bottom three bits because swap cache
45  *     entries use the top 29 bits for TLB2.
46  *
47  *   - CACHE COHERENT bit (M) has no effect on original PPC440 cores,
48  *     because it doesn't support SMP. However, some later 460 variants
49  *     have -some- form of SMP support and so I keep the bit there for
50  *     future use
51  *
52  * With the PPC 44x Linux implementation, the 0-11th LSBs of the PTE are used
53  * for memory protection related functions (see PTE structure in
54  * include/asm-ppc/mmu.h).  The _PAGE_XXX definitions in this file map to the
55  * above bits.  Note that the bit values are CPU specific, not architecture
56  * specific.
57  *
58  * The kernel PTE entry holds an arch-dependent swp_entry structure under
59  * certain situations. In other words, in such situations some portion of
60  * the PTE bits are used as a swp_entry. In the PPC implementation, the
61  * 3-24th LSB are shared with swp_entry, however the 0-2nd three LSB still
62  * hold protection values. That means the three protection bits are
63  * reserved for both PTE and SWAP entry at the most significant three
64  * LSBs.
65  *
66  * There are three protection bits available for SWAP entry:
67  *	_PAGE_PRESENT
68  *	_PAGE_HASHPTE (if HW has)
69  *
70  * So those three bits have to be inside of 0-2nd LSB of PTE.
71  *
72  */
73 
74 #define _PAGE_PRESENT	0x00000001		/* S: PTE valid */
75 #define _PAGE_RW	0x00000002		/* S: Write permission */
76 #define _PAGE_EXEC	0x00000004		/* H: Execute permission */
77 #define _PAGE_ACCESSED	0x00000008		/* S: Page referenced */
78 #define _PAGE_DIRTY	0x00000010		/* S: Page dirty */
79 #define _PAGE_SPECIAL	0x00000020		/* S: Special page */
80 #define _PAGE_USER	0x00000040		/* S: User page */
81 #define _PAGE_ENDIAN	0x00000080		/* H: E bit */
82 #define _PAGE_GUARDED	0x00000100		/* H: G bit */
83 #define _PAGE_COHERENT	0x00000200		/* H: M bit */
84 #define _PAGE_NO_CACHE	0x00000400		/* H: I bit */
85 #define _PAGE_WRITETHRU	0x00000800		/* H: W bit */
86 
87 /* TODO: Add large page lowmem mapping support */
88 #define _PMD_PRESENT	0
89 #define _PMD_PRESENT_MASK (PAGE_MASK)
90 #define _PMD_BAD	(~PAGE_MASK)
91 
92 /* ERPN in a PTE never gets cleared, ignore it */
93 #define _PTE_NONE_MASK	0xffffffff00000000ULL
94 
95 
96 #endif /* __KERNEL__ */
97 #endif /*  _ASM_POWERPC_NOHASH_32_PTE_44x_H */
98