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Diffstat (limited to 'c/src/lib/libcpu/powerpc/shared/include/pgtable.h')
-rw-r--r-- | c/src/lib/libcpu/powerpc/shared/include/pgtable.h | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/c/src/lib/libcpu/powerpc/shared/include/pgtable.h b/c/src/lib/libcpu/powerpc/shared/include/pgtable.h new file mode 100644 index 0000000000..30960b68b5 --- /dev/null +++ b/c/src/lib/libcpu/powerpc/shared/include/pgtable.h @@ -0,0 +1,146 @@ +/* + * pgtable.h + * + * PowerPC memory management structures + * + * It is a stripped down version of linux ppc file... + * + * Copyright (C) 1999 Eric Valette (valette@crf.canon.fr) + * Canon Centre Recherche France. + * + * The license and distribution terms for this file may be + * found in found in the file LICENSE in this distribution or at + * http://www.OARcorp.com/rtems/license.html. + * + * $Id$ + */ + +#ifndef _PPC_PGTABLE_H +#define _PPC_PGTABLE_H + +/* + * The PowerPC MMU uses a hash table containing PTEs, together with + * a set of 16 segment registers (on 32-bit implementations), to define + * the virtual to physical address mapping. + * + * We use the hash table as an extended TLB, i.e. a cache of currently + * active mappings. We maintain a two-level page table tree, much like + * that used by the i386, for the sake of the Linux memory management code. + * Low-level assembler code in head.S (procedure hash_page) is responsible + * for extracting ptes from the tree and putting them into the hash table + * when necessary, and updating the accessed and modified bits in the + * page table tree. + * + * The PowerPC MPC8xx uses a TLB with hardware assisted, software tablewalk. + * We also use the two level tables, but we can put the real bits in them + * needed for the TLB and tablewalk. These definitions require Mx_CTR.PPM = 0, + * Mx_CTR.PPCS = 0, and MD_CTR.TWAM = 1. The level 2 descriptor has + * additional page protection (when Mx_CTR.PPCS = 1) that allows TLB hit + * based upon user/super access. The TLB does not have accessed nor write + * protect. We assume that if the TLB get loaded with an entry it is + * accessed, and overload the changed bit for write protect. We use + * two bits in the software pte that are supposed to be set to zero in + * the TLB entry (24 and 25) for these indicators. Although the level 1 + * descriptor contains the guarded and writethrough/copyback bits, we can + * set these at the page level since they get copied from the Mx_TWC + * register when the TLB entry is loaded. We will use bit 27 for guard, since + * that is where it exists in the MD_TWC, and bit 26 for writethrough. + * These will get masked from the level 2 descriptor at TLB load time, and + * copied to the MD_TWC before it gets loaded. + */ + +/* PMD_SHIFT determines the size of the area mapped by the second-level page tables */ +#define PMD_SHIFT 22 +#define PMD_SIZE (1UL << PMD_SHIFT) +#define PMD_MASK (~(PMD_SIZE-1)) + +/* PGDIR_SHIFT determines what a third-level page table entry can map */ +#define PGDIR_SHIFT 22 +#define PGDIR_SIZE (1UL << PGDIR_SHIFT) +#define PGDIR_MASK (~(PGDIR_SIZE-1)) + +/* + * entries per page directory level: our page-table tree is two-level, so + * we don't really have any PMD directory. + */ +#define PTRS_PER_PTE 1024 +#define PTRS_PER_PMD 1 +#define PTRS_PER_PGD 1024 +#define USER_PTRS_PER_PGD (TASK_SIZE / PGDIR_SIZE) + +/* Just any arbitrary offset to the start of the vmalloc VM area: the + * current 64MB value just means that there will be a 64MB "hole" after the + * physical memory until the kernel virtual memory starts. That means that + * any out-of-bounds memory accesses will hopefully be caught. + * The vmalloc() routines leaves a hole of 4kB between each vmalloced + * area for the same reason. ;) + * + * We no longer map larger than phys RAM with the BATs so we don't have + * to worry about the VMALLOC_OFFSET causing problems. We do have to worry + * about clashes between our early calls to ioremap() that start growing down + * from ioremap_base being run into the VM area allocations (growing upwards + * from VMALLOC_START). For this reason we have ioremap_bot to check when + * we actually run into our mappings setup in the early boot with the VM + * system. This really does become a problem for machines with good amounts + * of RAM. -- Cort + */ +#define VMALLOC_OFFSET (0x4000000) /* 64M */ +#define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))) +#define VMALLOC_VMADDR(x) ((unsigned long)(x)) +#define VMALLOC_END ioremap_bot + +/* + * Bits in a linux-style PTE. These match the bits in the + * (hardware-defined) PowerPC PTE as closely as possible. + */ +#define _PAGE_PRESENT 0x001 /* software: pte contains a translation */ +#define _PAGE_USER 0x002 /* matches one of the PP bits */ +#define _PAGE_RW 0x004 /* software: user write access allowed */ +#define _PAGE_GUARDED 0x008 +#define _PAGE_COHERENT 0x010 /* M: enforce memory coherence (SMP systems) */ +#define _PAGE_NO_CACHE 0x020 /* I: cache inhibit */ +#define _PAGE_WRITETHRU 0x040 /* W: cache write-through */ +#define _PAGE_DIRTY 0x080 /* C: page changed */ +#define _PAGE_ACCESSED 0x100 /* R: page referenced */ +#define _PAGE_HWWRITE 0x200 /* software: _PAGE_RW & _PAGE_DIRTY */ +#define _PAGE_SHARED 0 + +#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY) + +#define _PAGE_BASE _PAGE_PRESENT | _PAGE_ACCESSED +#define _PAGE_WRENABLE _PAGE_RW | _PAGE_DIRTY | _PAGE_HWWRITE + +#define PAGE_NONE __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED) + +#define PAGE_SHARED __pgprot(_PAGE_BASE | _PAGE_RW | _PAGE_USER | \ + _PAGE_SHARED) +#define PAGE_COPY __pgprot(_PAGE_BASE | _PAGE_USER) +#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER) +#define PAGE_KERNEL __pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_SHARED) +#define PAGE_KERNEL_CI __pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_SHARED | \ + _PAGE_NO_CACHE ) + +/* + * The PowerPC can only do execute protection on a segment (256MB) basis, + * not on a page basis. So we consider execute permission the same as read. + * Also, write permissions imply read permissions. + * This is the closest we can get.. + */ +#define __P000 PAGE_NONE +#define __P001 PAGE_READONLY +#define __P010 PAGE_COPY +#define __P011 PAGE_COPY +#define __P100 PAGE_READONLY +#define __P101 PAGE_READONLY +#define __P110 PAGE_COPY +#define __P111 PAGE_COPY + +#define __S000 PAGE_NONE +#define __S001 PAGE_READONLY +#define __S010 PAGE_SHARED +#define __S011 PAGE_SHARED +#define __S100 PAGE_READONLY +#define __S101 PAGE_READONLY +#define __S110 PAGE_SHARED +#define __S111 PAGE_SHARED +#endif /* _PPC_PGTABLE_H */ |