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 <asm/memory.h>
  17
  18 /*
  19  * The table below defines the page protection levels that we insert into our
  20  * Linux page table version.  These get translated into the best that the
  21  * architecture can perform.  Note that on most ARM hardware:
  22  *  1) We cannot do execute protection
  23  *  2) If we could do execute protection, then read is implied
  24  *  3) write implies read permissions
  25  */
  26 #define __P000  PAGE_NONE
  27 #define __P001  PAGE_READONLY
  28 #define __P010  PAGE_COPY
  29 #define __P011  PAGE_COPY
  30 #define __P100  PAGE_READONLY
  31 #define __P101  PAGE_READONLY
  32 #define __P110  PAGE_COPY
  33 #define __P111  PAGE_COPY
  34
  35 #define __S000  PAGE_NONE
  36 #define __S001  PAGE_READONLY
  37 #define __S010  PAGE_SHARED
  38 #define __S011  PAGE_SHARED
  39 #define __S100  PAGE_READONLY
  40 #define __S101  PAGE_READONLY
  41 #define __S110  PAGE_SHARED
  42 #define __S111  PAGE_SHARED
  43
  44 /*
  45  * PMD_SHIFT determines the size of the area a second-level page table can map
  46  * PGDIR_SHIFT determines what a third-level page table entry can map
  47  */
  48 #define PGD_SHIFT               25
  49 #define PMD_SHIFT               20
  50
  51 #define PGD_SIZE                (1UL << PGD_SHIFT)
  52 #define PGD_MASK                (~(PGD_SIZE-1))
  53 #define PMD_SIZE                (1UL << PMD_SHIFT)
  54 #define PMD_MASK                (~(PMD_SIZE-1))
  55
  56 /* The kernel likes to use these names for the above (ick) */
  57 #define PGDIR_SIZE PGD_SIZE
  58 #define PGDIR_MASK PGD_MASK
  59
  60 #define PTRS_PER_PGD            32
  61 #define PTRS_PER_PMD            1
  62 #define PTRS_PER_PTE            32
  63
  64 /*
  65  * This is the lowest virtual address we can permit any user space
  66  * mapping to be mapped at.  This is particularly important for
  67  * non-high vector CPUs.
  68  */
  69 #define FIRST_USER_ADDRESS      PAGE_SIZE
  70
  71 #define FIRST_USER_PGD_NR       1
  72 #define USER_PTRS_PER_PGD       ((TASK_SIZE/PGD_SIZE) - FIRST_USER_PGD_NR)
  73
  74 // FIXME - WTF?
  75 #define LIBRARY_TEXT_START      0x0c000000
  76
  77
  78
  79 #ifndef __ASSEMBLY__
  80 extern void __pte_error(const char *file, int line, unsigned long val);
  81 extern void __pmd_error(const char *file, int line, unsigned long val);
  82 extern void __pgd_error(const char *file, int line, unsigned long val);
  83
  84 #define pte_ERROR(pte)          __pte_error(__FILE__, __LINE__, pte_val(pte))
  85 #define pmd_ERROR(pmd)          __pmd_error(__FILE__, __LINE__, pmd_val(pmd))
  86 #define pgd_ERROR(pgd)          __pgd_error(__FILE__, __LINE__, pgd_val(pgd))
  87
  88 /*
  89  * ZERO_PAGE is a global shared page that is always zero: used
  90  * for zero-mapped memory areas etc..
  91  */
  92 extern struct page *empty_zero_page;
  93 #define ZERO_PAGE(vaddr)        (empty_zero_page)
  94
  95 #define pte_pfn(pte)            (pte_val(pte) >> PAGE_SHIFT)
  96 #define pte_page(pte)           (pfn_to_page(pte_pfn(pte)))
  97 #define pfn_pte(pfn,prot)       (__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot)))
  98 #define pages_to_mb(x)          ((x) >> (20 - PAGE_SHIFT))
  99 #define mk_pte(page,prot)       pfn_pte(page_to_pfn(page),prot)
 100
 101 /*
 102  * Terminology: PGD = Page Directory, PMD = Page Middle Directory,
 103  *              PTE = Page Table Entry
 104  *
 105  * on arm26 we have no 2nd level page table. we simulate this by removing the
 106  * PMD.
 107  *
 108  * pgd_none is 0 to prevernt pmd_alloc() calling __pmd_alloc(). This causes it
 109  * to return pmd_offset(pgd,addr) which is a pointer to the pgd (IOW, a no-op).
 110  *
 111  * however, to work this way, whilst we are allocating 32 pgds, containing 32
 112  * PTEs, the actual work is done on the PMDs, thus:
 113  *
 114  * instead of  mm->pgd->pmd->pte
 115  * we have     mm->pgdpmd->pte
 116  *
 117  * IOW, think of PGD operations and PMD ones as being the same thing, just
 118  * that PGD stuff deals with the mm_struct side of things, wheras PMD stuff
 119  * deals with the pte side of things.
 120  *
 121  * additionally, we store some bits in the PGD and PTE pointers:
 122  * PGDs:
 123  *   o The lowest (1) bit of the PGD is to determine if it is present or swap.
 124  *   o The 2nd bit of the PGD is unused and must be zero.
 125  *   o The top 6 bits of the PGD must be zero.
 126  * PTEs:
 127  *   o The lower 5 bits of a pte are flags. bit 1 is the 'present' flag. The
 128  *     others determine the pages attributes.
 129  *
 130  * the pgd_val, pmd_val, and pte_val macros seem to be private to our code.
 131  * They get the RAW value of the PGD/PMD/PTE entry, including our flags
 132  * encoded into the pointers.
 133  *
 134  * The pgd_offset, pmd_offset, and pte_offset macros are used by the kernel,
 135  * so they shouldnt have our flags attached.
 136  *
 137  * If you understood that, feel free to explain it to me...
 138  *
 139  */
 140
 141 #define _PMD_PRESENT     (0x01)
 142
 143 /* These definitions allow us to optimise out stuff like pmd_alloc() */
 144 #define pgd_none(pgd)           (0)
 145 #define pgd_bad(pgd)            (0)
 146 #define pgd_present(pgd)        (1)
 147 #define pgd_clear(pgdp)         do { } while (0)
 148
 149 /* Whilst these handle our actual 'page directory' (the agglomeration of pgd and pmd)
 150  */
 151 #define pmd_none(pmd)           (!pmd_val(pmd))
 152 #define pmd_bad(pmd)            ((pmd_val(pmd) & 0xfc000002))
 153 #define pmd_present(pmd)        (pmd_val(pmd) & _PMD_PRESENT)
 154 #define set_pmd(pmd_ptr, pmd)   ((*(pmd_ptr)) = (pmd))
 155 #define pmd_clear(pmdp)         set_pmd(pmdp, __pmd(0))
 156
 157 /* and these handle our pte tables */
 158 #define pte_none(pte)           (!pte_val(pte))
 159 #define pte_present(pte)        (pte_val(pte) & _PAGE_PRESENT)
 160 #define set_pte(pte_ptr, pte)   ((*(pte_ptr)) = (pte))
 161 #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
 162 #define pte_clear(mm,addr,ptep) set_pte_at((mm),(addr),(ptep), __pte(0))
 163
 164 /* macros to ease the getting of pointers to stuff... */
 165 #define pgd_offset(mm, addr)    ((pgd_t *)(mm)->pgd        + __pgd_index(addr))
 166 #define pmd_offset(pgd, addr)   ((pmd_t *)(pgd))
 167 #define pte_offset(pmd, addr)   ((pte_t *)pmd_page(*(pmd)) + __pte_index(addr))
 168
 169 /* there is no __pmd_index as we dont use pmds */
 170 #define __pgd_index(addr)       ((addr) >> PGD_SHIFT)
 171 #define __pte_index(addr)       (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 172
 173
 174 /* Keep the kernel happy */
 175 #define pgd_index(addr)         __pgd_index(addr)
 176 #define pgd_offset_k(addr)      (pgd_offset(&init_mm, addr))
 177
 178 /*
 179  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
 180  * area for the same reason. ;) FIXME: surely 1 page not 4k ?
 181  */
 182 #define VMALLOC_START     0x01a00000
 183 #define VMALLOC_END       0x01c00000
 184
 185 /* Is pmd_page supposed to return a pointer to a page in some arches? ours seems to
 186  * return a pointer to memory (no special alignment)
 187  */
 188 #define pmd_page(pmd)  ((struct page *)(pmd_val((pmd)) & ~_PMD_PRESENT))
 189 #define pmd_page_vaddr(pmd) ((pte_t *)(pmd_val((pmd)) & ~_PMD_PRESENT))
 190
 191 #define pte_offset_kernel(dir,addr)     (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 192
 193 #define pte_offset_map(dir,addr)        (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 194 #define pte_offset_map_nested(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 195 #define pte_unmap(pte)                  do { } while (0)
 196 #define pte_unmap_nested(pte)           do { } while (0)
 197
 198
 199 #define _PAGE_PRESENT   0x01
 200 #define _PAGE_READONLY  0x02
 201 #define _PAGE_NOT_USER  0x04
 202 #define _PAGE_OLD       0x08
 203 #define _PAGE_CLEAN     0x10
 204
 205 // an old page has never been read.
 206 // a clean page has never been written.
 207
 208 /*                               -- present --   -- !dirty --  --- !write ---   ---- !user --- */
 209 #define PAGE_NONE       __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY | _PAGE_NOT_USER)
 210 #define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_CLEAN                                  )
 211 #define PAGE_COPY       __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY                 )
 212 #define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY                 )
 213 #define PAGE_KERNEL     __pgprot(_PAGE_PRESENT                                | _PAGE_NOT_USER)
 214
 215 #define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_OLD | _PAGE_CLEAN)
 216
 217 /*
 218  * The following only work if pte_present() is true.
 219  * Undefined behaviour if not..
 220  */
 221 #define pte_read(pte)                   (!(pte_val(pte) & _PAGE_NOT_USER))
 222 #define pte_write(pte)                  (!(pte_val(pte) & _PAGE_READONLY))
 223 #define pte_exec(pte)                   (!(pte_val(pte) & _PAGE_NOT_USER))
 224 #define pte_dirty(pte)                  (!(pte_val(pte) & _PAGE_CLEAN))
 225 #define pte_young(pte)                  (!(pte_val(pte) & _PAGE_OLD))
 226 //ONLY when !pte_present() I think. nicked from arm32 (FIXME!)
 227 #define pte_file(pte)                   (!(pte_val(pte) & _PAGE_OLD))
 228
 229 #define PTE_BIT_FUNC(fn,op)                     \
 230 static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
 231
 232 PTE_BIT_FUNC(wrprotect, |=  _PAGE_READONLY);
 233 PTE_BIT_FUNC(mkwrite,   &= ~_PAGE_READONLY);
 234 PTE_BIT_FUNC(exprotect, |=  _PAGE_NOT_USER);
 235 PTE_BIT_FUNC(mkexec,    &= ~_PAGE_NOT_USER);
 236 PTE_BIT_FUNC(mkclean,   |=  _PAGE_CLEAN);
 237 PTE_BIT_FUNC(mkdirty,   &= ~_PAGE_CLEAN);
 238 PTE_BIT_FUNC(mkold,     |=  _PAGE_OLD);
 239 PTE_BIT_FUNC(mkyoung,   &= ~_PAGE_OLD);
 240
 241 /*
 242  * We don't store cache state bits in the page table here. FIXME - or do we?
 243  */
 244 #define pgprot_noncached(prot)  (prot)
 245 #define pgprot_writecombine(prot) (prot) //FIXME - is a no-op?
 246
 247 extern void pgtable_cache_init(void);
 248
 249 //FIXME - nicked from arm32 and brutally hacked. probably wrong.
 250 #define pte_to_pgoff(x) (pte_val(x) >> 2)
 251 #define pgoff_to_pte(x) __pte(((x) << 2) & ~_PAGE_OLD)
 252
 253 //FIXME - next line borrowed from arm32. is it right?
 254 #define PTE_FILE_MAX_BITS       30
 255
 256
 257 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 258 {
 259         pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot);
 260         return pte;
 261 }
 262
 263 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
 264
 265 /* Encode and decode a swap entry.
 266  *
 267  * We support up to 32GB of swap on 4k machines
 268  */
 269 #define __swp_type(x)           (((x).val >> 2) & 0x7f)
 270 #define __swp_offset(x)         ((x).val >> 9)
 271 #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 2) | ((offset) << 9) })
 272 #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
 273 #define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })
 274
 275 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
 276 /* FIXME: this is not correct */
 277 #define kern_addr_valid(addr)   (1)
 278
 279 /*
 280  * Conversion functions: convert a page and protection to a page entry,
 281  * and a page entry and page directory to the page they refer to.
 282  */
 283 static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
 284 {
 285         pte_t pte;
 286         pte_val(pte) = physpage | pgprot_val(pgprot);
 287         return pte;
 288 }
 289
 290
 291 #include <asm-generic/pgtable.h>
 292
 293 /*
 294  * remap a physical page `pfn' of size `size' with page protection `prot'
 295  * into virtual address `from'
 296  */
 297 #define io_remap_pfn_range(vma,from,pfn,size,prot) \
 298                 remap_pfn_range(vma, from, pfn, size, prot)
 299
 300 #endif /* !__ASSEMBLY__ */
 301
 302 #endif /* _ASMARM_PGTABLE_H */