diff options
Diffstat (limited to 'arch/powerpc/include/asm/pte-44x.h')
| -rw-r--r-- | arch/powerpc/include/asm/pte-44x.h | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/pte-44x.h b/arch/powerpc/include/asm/pte-44x.h new file mode 100644 index 00000000000..37e98bcf83e --- /dev/null +++ b/arch/powerpc/include/asm/pte-44x.h @@ -0,0 +1,102 @@ +#ifndef _ASM_POWERPC_PTE_44x_H +#define _ASM_POWERPC_PTE_44x_H +#ifdef __KERNEL__ + +/* + * Definitions for PPC440 + * + * Because of the 3 word TLB entries to support 36-bit addressing, + * the attribute are difficult to map in such a fashion that they + * are easily loaded during exception processing. I decided to + * organize the entry so the ERPN is the only portion in the + * upper word of the PTE and the attribute bits below are packed + * in as sensibly as they can be in the area below a 4KB page size + * oriented RPN. This at least makes it easy to load the RPN and + * ERPN fields in the TLB. -Matt + * + * This isn't entirely true anymore, at least some bits are now + * easier to move into the TLB from the PTE. -BenH. + * + * Note that these bits preclude future use of a page size + * less than 4KB. + * + * + * PPC 440 core has following TLB attribute fields; + * + * TLB1: + * 0 1 2 3 4 ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 + * RPN................................. - - - - - - ERPN....... + * + * TLB2: + * 0 1 2 3 4 ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 + * - - - - - - U0 U1 U2 U3 W I M G E - UX UW UR SX SW SR + * + * Newer 440 cores (440x6 as used on AMCC 460EX/460GT) have additional + * TLB2 storage attibute fields. Those are: + * + * TLB2: + * 0...10 11 12 13 14 15 16...31 + * no change WL1 IL1I IL1D IL2I IL2D no change + * + * There are some constrains and options, to decide mapping software bits + * into TLB entry. + * + * - PRESENT *must* be in the bottom three bits because swap cache + * entries use the top 29 bits for TLB2. + * + * - FILE *must* be in the bottom three bits because swap cache + * entries use the top 29 bits for TLB2. + * + * - CACHE COHERENT bit (M) has no effect on original PPC440 cores, + * because it doesn't support SMP. However, some later 460 variants + * have -some- form of SMP support and so I keep the bit there for + * future use + * + * With the PPC 44x Linux implementation, the 0-11th LSBs of the PTE are used + * for memory protection related functions (see PTE structure in + * include/asm-ppc/mmu.h). The _PAGE_XXX definitions in this file map to the + * above bits. Note that the bit values are CPU specific, not architecture + * specific. + * + * The kernel PTE entry holds an arch-dependent swp_entry structure under + * certain situations. In other words, in such situations some portion of + * the PTE bits are used as a swp_entry. In the PPC implementation, the + * 3-24th LSB are shared with swp_entry, however the 0-2nd three LSB still + * hold protection values. That means the three protection bits are + * reserved for both PTE and SWAP entry at the most significant three + * LSBs. + * + * There are three protection bits available for SWAP entry: + * _PAGE_PRESENT + * _PAGE_FILE + * _PAGE_HASHPTE (if HW has) + * + * So those three bits have to be inside of 0-2nd LSB of PTE. + * + */ + +#define _PAGE_PRESENT 0x00000001 /* S: PTE valid */ +#define _PAGE_RW 0x00000002 /* S: Write permission */ +#define _PAGE_FILE 0x00000004 /* S: nonlinear file mapping */ +#define _PAGE_HWEXEC 0x00000004 /* H: Execute permission */ +#define _PAGE_ACCESSED 0x00000008 /* S: Page referenced */ +#define _PAGE_DIRTY 0x00000010 /* S: Page dirty */ +#define _PAGE_SPECIAL 0x00000020 /* S: Special page */ +#define _PAGE_USER 0x00000040 /* S: User page */ +#define _PAGE_ENDIAN 0x00000080 /* H: E bit */ +#define _PAGE_GUARDED 0x00000100 /* H: G bit */ +#define _PAGE_COHERENT 0x00000200 /* H: M bit */ +#define _PAGE_NO_CACHE 0x00000400 /* H: I bit */ +#define _PAGE_WRITETHRU 0x00000800 /* H: W bit */ + +/* TODO: Add large page lowmem mapping support */ +#define _PMD_PRESENT 0 +#define _PMD_PRESENT_MASK (PAGE_MASK) +#define _PMD_BAD (~PAGE_MASK) + +/* ERPN in a PTE never gets cleared, ignore it */ +#define _PTE_NONE_MASK 0xffffffff00000000ULL + + +#endif /* __KERNEL__ */ +#endif /* _ASM_POWERPC_PTE_44x_H */ |