release/src-rt-6.x.4708/linux/linux-2.6.36/arch/powerpc/include/asm/pte-44x.h

   1 #ifndef _ASM_POWERPC_PTE_44x_H
   2 #define _ASM_POWERPC_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  *   - FILE *must* be in the bottom three bits because swap cache
  48  *     entries use the top 29 bits for TLB2.
  49  *
  50  *   - CACHE COHERENT bit (M) has no effect on original PPC440 cores,
  51  *     because it doesn't support SMP. However, some later 460 variants
  52  *     have -some- form of SMP support and so I keep the bit there for
  53  *     future use
  54  *
  55  * With the PPC 44x Linux implementation, the 0-11th LSBs of the PTE are used
  56  * for memory protection related functions (see PTE structure in
  57  * include/asm-ppc/mmu.h).  The _PAGE_XXX definitions in this file map to the
  58  * above bits.  Note that the bit values are CPU specific, not architecture
  59  * specific.
  60  *
  61  * The kernel PTE entry holds an arch-dependent swp_entry structure under
  62  * certain situations. In other words, in such situations some portion of
  63  * the PTE bits are used as a swp_entry. In the PPC implementation, the
  64  * 3-24th LSB are shared with swp_entry, however the 0-2nd three LSB still
  65  * hold protection values. That means the three protection bits are
  66  * reserved for both PTE and SWAP entry at the most significant three
  67  * LSBs.
  68  *
  69  * There are three protection bits available for SWAP entry:
  70  *      _PAGE_PRESENT
  71  *      _PAGE_FILE
  72  *      _PAGE_HASHPTE (if HW has)
  73  *
  74  * So those three bits have to be inside of 0-2nd LSB of PTE.
  75  *
  76  */
  77
  78 #define _PAGE_PRESENT   0x00000001              /* S: PTE valid */
  79 #define _PAGE_RW        0x00000002              /* S: Write permission */
  80 #define _PAGE_FILE      0x00000004              /* S: nonlinear file mapping */
  81 #define _PAGE_EXEC      0x00000004              /* H: Execute permission */
  82 #define _PAGE_ACCESSED  0x00000008              /* S: Page referenced */
  83 #define _PAGE_DIRTY     0x00000010              /* S: Page dirty */
  84 #define _PAGE_SPECIAL   0x00000020              /* S: Special page */
  85 #define _PAGE_USER      0x00000040              /* S: User page */
  86 #define _PAGE_ENDIAN    0x00000080              /* H: E bit */
  87 #define _PAGE_GUARDED   0x00000100              /* H: G bit */
  88 #define _PAGE_COHERENT  0x00000200              /* H: M bit */
  89 #define _PAGE_NO_CACHE  0x00000400              /* H: I bit */
  90 #define _PAGE_WRITETHRU 0x00000800              /* H: W bit */
  91
  92 /* TODO: Add large page lowmem mapping support */
  93 #define _PMD_PRESENT    0
  94 #define _PMD_PRESENT_MASK (PAGE_MASK)
  95 #define _PMD_BAD        (~PAGE_MASK)
  96
  97 /* ERPN in a PTE never gets cleared, ignore it */
  98 #define _PTE_NONE_MASK  0xffffffff00000000ULL
  99
 100
 101 #endif /* __KERNEL__ */
 102 #endif /*  _ASM_POWERPC_PTE_44x_H */