LXR linux/include/asm-arm26/pgtable.h

   1/*
   2 *  linux/include/asm-arm26/pgtable.h
   3 *
   4 *  Copyright (C) 2000-2002 Russell King
   5 *  Copyright (C) 2003 Ian Molton
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11#ifndef _ASMARM_PGTABLE_H
  12#define _ASMARM_PGTABLE_H
  13
  14#include <asm-generic/4level-fixup.h>
  15
  16#include <linux/config.h>
  17#include <asm/memory.h>
  18
  19/*
  20 * The table below defines the page protection levels that we insert into our
  21 * Linux page table version.  These get translated into the best that the
  22 * architecture can perform.  Note that on most ARM hardware:
  23 *  1) We cannot do execute protection
  24 *  2) If we could do execute protection, then read is implied
  25 *  3) write implies read permissions
  26 */
  27#define __P000  PAGE_NONE
  28#define __P001  PAGE_READONLY
  29#define __P010  PAGE_COPY
  30#define __P011  PAGE_COPY
  31#define __P100  PAGE_READONLY
  32#define __P101  PAGE_READONLY
  33#define __P110  PAGE_COPY
  34#define __P111  PAGE_COPY
  35
  36#define __S000  PAGE_NONE
  37#define __S001  PAGE_READONLY
  38#define __S010  PAGE_SHARED
  39#define __S011  PAGE_SHARED
  40#define __S100  PAGE_READONLY
  41#define __S101  PAGE_READONLY
  42#define __S110  PAGE_SHARED
  43#define __S111  PAGE_SHARED
  44
  45/*
  46 * PMD_SHIFT determines the size of the area a second-level page table can map
  47 * PGDIR_SHIFT determines what a third-level page table entry can map
  48 */
  49#define PGD_SHIFT               25
  50#define PMD_SHIFT               20
  51
  52#define PGD_SIZE                (1UL << PGD_SHIFT)
  53#define PGD_MASK                (~(PGD_SIZE-1))
  54#define PMD_SIZE                (1UL << PMD_SHIFT)
  55#define PMD_MASK                (~(PMD_SIZE-1))
  56
  57/* The kernel likes to use these names for the above (ick) */
  58#define PGDIR_SIZE PGD_SIZE
  59#define PGDIR_MASK PGD_MASK
  60
  61#define PTRS_PER_PGD            32
  62#define PTRS_PER_PMD            1
  63#define PTRS_PER_PTE            32
  64
  65#define FIRST_USER_PGD_NR       1
  66#define USER_PTRS_PER_PGD       ((TASK_SIZE/PGD_SIZE) - FIRST_USER_PGD_NR)
  67
  68// FIXME - WTF?
  69#define LIBRARY_TEXT_START      0x0c000000
  70
  71
  72
  73#ifndef __ASSEMBLY__
  74extern void __pte_error(const char *file, int line, unsigned long val);
  75extern void __pmd_error(const char *file, int line, unsigned long val);
  76extern void __pgd_error(const char *file, int line, unsigned long val);
  77
  78#define pte_ERROR(pte)          __pte_error(__FILE__, __LINE__, pte_val(pte))
  79#define pmd_ERROR(pmd)          __pmd_error(__FILE__, __LINE__, pmd_val(pmd))
  80#define pgd_ERROR(pgd)          __pgd_error(__FILE__, __LINE__, pgd_val(pgd))
  81
  82/*
  83 * ZERO_PAGE is a global shared page that is always zero: used
  84 * for zero-mapped memory areas etc..
  85 */
  86extern struct page *empty_zero_page;
  87#define ZERO_PAGE(vaddr)        (empty_zero_page)
  88
  89#define pte_pfn(pte)            (pte_val(pte) >> PAGE_SHIFT)
  90#define pte_page(pte)           (pfn_to_page(pte_pfn(pte)))
  91#define pfn_pte(pfn,prot)       (__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot)))
  92#define pages_to_mb(x)          ((x) >> (20 - PAGE_SHIFT))
  93#define mk_pte(page,prot)       pfn_pte(page_to_pfn(page),prot)
  94#define page_pte_prot(page,prot)        mk_pte(page, prot)
  95#define page_pte(page)          mk_pte(page, __pgprot(0))
  96
  97/*
  98 * Terminology: PGD = Page Directory, PMD = Page Middle Directory,
  99 *              PTE = Page Table Entry
 100 *
 101 * on arm26 we have no 2nd level page table. we simulate this by removing the
 102 * PMD.
 103 *
 104 * pgd_none is 0 to prevernt pmd_alloc() calling __pmd_alloc(). This causes it
 105 * to return pmd_offset(pgd,addr) which is a pointer to the pgd (IOW, a no-op).
 106 *
 107 * however, to work this way, whilst we are allocating 32 pgds, containing 32
 108 * PTEs, the actual work is done on the PMDs, thus:
 109 *
 110 * instead of  mm->pgd->pmd->pte
 111 * we have     mm->pgdpmd->pte
 112 *
 113 * IOW, think of PGD operations and PMD ones as being the same thing, just
 114 * that PGD stuff deals with the mm_struct side of things, wheras PMD stuff
 115 * deals with the pte side of things.
 116 *
 117 * additionally, we store some bits in the PGD and PTE pointers: 
 118 * PGDs:
 119 *   o The lowest (1) bit of the PGD is to determine if it is present or swap.
 120 *   o The 2nd bit of the PGD is unused and must be zero.
 121 *   o The top 6 bits of the PGD must be zero. 
 122 * PTEs:
 123 *   o The lower 5 bits of a pte are flags. bit 1 is the 'present' flag. The
 124 *     others determine the pages attributes.
 125 *
 126 * the pgd_val, pmd_val, and pte_val macros seem to be private to our code.
 127 * They get the RAW value of the PGD/PMD/PTE entry, including our flags
 128 * encoded into the pointers.
 129 * 
 130 * The pgd_offset, pmd_offset, and pte_offset macros are used by the kernel,
 131 * so they shouldnt have our flags attached.
 132 *
 133 * If you understood that, feel free to explain it to me...
 134 *
 135 */
 136
 137#define _PMD_PRESENT     (0x01)
 138
 139/* These definitions allow us to optimise out stuff like pmd_alloc() */
 140#define pgd_none(pgd)           (0) 
 141#define pgd_bad(pgd)            (0)
 142#define pgd_present(pgd)        (1)
 143#define pgd_clear(pgdp)         do { } while (0)
 144
 145/* Whilst these handle our actual 'page directory' (the agglomeration of pgd and pmd)
 146 */
 147#define pmd_none(pmd)           (!pmd_val(pmd))
 148#define pmd_bad(pmd)            ((pmd_val(pmd) & 0xfc000002))
 149#define pmd_present(pmd)        (pmd_val(pmd) & _PMD_PRESENT)
 150#define set_pmd(pmd_ptr, pmd)   ((*(pmd_ptr)) = (pmd))
 151#define pmd_clear(pmdp)         set_pmd(pmdp, __pmd(0))
 152
 153/* and these handle our pte tables */
 154#define pte_none(pte)           (!pte_val(pte))
 155#define pte_present(pte)        (pte_val(pte) & _PAGE_PRESENT)
 156#define set_pte(pte_ptr, pte)   ((*(pte_ptr)) = (pte))
 157#define pte_clear(ptep)         set_pte((ptep), __pte(0))
 158
 159/* macros to ease the getting of pointers to stuff... */
 160#define pgd_offset(mm, addr)    ((pgd_t *)(mm)->pgd        + __pgd_index(addr))
 161#define pmd_offset(pgd, addr)   ((pmd_t *)(pgd))
 162#define pte_offset(pmd, addr)   ((pte_t *)pmd_page(*(pmd)) + __pte_index(addr))
 163
 164/* there is no __pmd_index as we dont use pmds */
 165#define __pgd_index(addr)       ((addr) >> PGD_SHIFT)
 166#define __pte_index(addr)       (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 167
 168
 169/* Keep the kernel happy */
 170#define pgd_index(addr)         __pgd_index(addr)
 171#define pgd_offset_k(addr)      (pgd_offset(&init_mm, addr))
 172
 173/*
 174 * The vmalloc() routines leaves a hole of 4kB between each vmalloced
 175 * area for the same reason. ;) FIXME: surely 1 page not 4k ?
 176 */
 177#define VMALLOC_START     0x01a00000
 178#define VMALLOC_END       0x01c00000
 179
 180/* Is pmd_page supposed to return a pointer to a page in some arches? ours seems to
 181 * return a pointer to memory (no special alignment)
 182 */
 183#define pmd_page(pmd)  ((struct page *)(pmd_val((pmd)) & ~_PMD_PRESENT))
 184#define pmd_page_kernel(pmd) ((pte_t *)(pmd_val((pmd)) & ~_PMD_PRESENT))
 185
 186#define pte_offset_kernel(dir,addr)     (pmd_page_kernel(*(dir)) + __pte_index(addr))
 187
 188#define pte_offset_map(dir,addr)        (pmd_page_kernel(*(dir)) + __pte_index(addr))
 189#define pte_offset_map_nested(dir,addr) (pmd_page_kernel(*(dir)) + __pte_index(addr))
 190#define pte_unmap(pte)                  do { } while (0)
 191#define pte_unmap_nested(pte)           do { } while (0)
 192
 193
 194#define _PAGE_PRESENT   0x01
 195#define _PAGE_READONLY  0x02
 196#define _PAGE_NOT_USER  0x04
 197#define _PAGE_OLD       0x08
 198#define _PAGE_CLEAN     0x10
 199
 200// an old page has never been read.
 201// a clean page has never been written.
 202
 203/*                               -- present --   -- !dirty --  --- !write ---   ---- !user --- */
 204#define PAGE_NONE       __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY | _PAGE_NOT_USER)
 205#define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_CLEAN                                  )
 206#define PAGE_COPY       __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY                 )
 207#define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY                 )
 208#define PAGE_KERNEL     __pgprot(_PAGE_PRESENT                                | _PAGE_NOT_USER)
 209
 210#define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_OLD | _PAGE_CLEAN)
 211
 212/*
 213 * The following only work if pte_present() is true.
 214 * Undefined behaviour if not..
 215 */
 216#define pte_read(pte)                   (!(pte_val(pte) & _PAGE_NOT_USER))
 217#define pte_write(pte)                  (!(pte_val(pte) & _PAGE_READONLY))
 218#define pte_exec(pte)                   (!(pte_val(pte) & _PAGE_NOT_USER))
 219#define pte_dirty(pte)                  (!(pte_val(pte) & _PAGE_CLEAN))
 220#define pte_young(pte)                  (!(pte_val(pte) & _PAGE_OLD))
 221//ONLY when !pte_present() I think. nicked from arm32 (FIXME!)
 222#define pte_file(pte)                   (!(pte_val(pte) & _PAGE_OLD))
 223
 224#define PTE_BIT_FUNC(fn,op)                     \
 225static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
 226
 227PTE_BIT_FUNC(wrprotect, |=  _PAGE_READONLY);
 228PTE_BIT_FUNC(mkwrite,   &= ~_PAGE_READONLY);
 229PTE_BIT_FUNC(exprotect, |=  _PAGE_NOT_USER);
 230PTE_BIT_FUNC(mkexec,    &= ~_PAGE_NOT_USER);
 231PTE_BIT_FUNC(mkclean,   |=  _PAGE_CLEAN);
 232PTE_BIT_FUNC(mkdirty,   &= ~_PAGE_CLEAN);
 233PTE_BIT_FUNC(mkold,     |=  _PAGE_OLD);
 234PTE_BIT_FUNC(mkyoung,   &= ~_PAGE_OLD);
 235
 236/*
 237 * We don't store cache state bits in the page table here. FIXME - or do we?
 238 */
 239#define pgprot_noncached(prot)  (prot)
 240#define pgprot_writecombine(prot) (prot) //FIXME - is a no-op?
 241
 242extern void pgtable_cache_init(void);
 243
 244//FIXME - nicked from arm32 and brutally hacked. probably wrong.
 245#define pte_to_pgoff(x) (pte_val(x) >> 2)
 246#define pgoff_to_pte(x) __pte(((x) << 2) & ~_PAGE_OLD)
 247
 248//FIXME - next line borrowed from arm32. is it right?
 249#define PTE_FILE_MAX_BITS       30
 250
 251
 252static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 253{
 254        pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot);
 255        return pte;
 256}
 257
 258extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
 259
 260/* Encode and decode a swap entry.
 261 *
 262 * We support up to 32GB of swap on 4k machines
 263 */
 264#define __swp_type(x)           (((x).val >> 2) & 0x7f)
 265#define __swp_offset(x)         ((x).val >> 9)
 266#define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 2) | ((offset) << 9) })
 267#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
 268#define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })
 269
 270/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
 271/* FIXME: this is not correct */
 272#define kern_addr_valid(addr)   (1)
 273
 274/*
 275 * Conversion functions: convert a page and protection to a page entry,
 276 * and a page entry and page directory to the page they refer to.
 277 */
 278static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
 279{
 280        pte_t pte;
 281        pte_val(pte) = physpage | pgprot_val(pgprot);
 282        return pte;
 283}
 284
 285
 286#include <asm-generic/pgtable.h>
 287
 288/*
 289 * remap a physical address `phys' of size `size' with page protection `prot'
 290 * into virtual address `from'
 291 */
 292#define io_remap_page_range(vma,from,phys,size,prot) \
 293                remap_pfn_range(vma, from, (phys) >> PAGE_SHIFT, size, prot)
 294
 295#endif /* !__ASSEMBLY__ */
 296
 297#endif /* _ASMARM_PGTABLE_H */
 298