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#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 */
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