root/include/asm-i386/pgtable.h

/* */

INCLUDED FROM

DEFINITIONS

1. pte_none
2. pte_present
3. pte_inuse
4. pte_clear
5. pte_reuse
6. pmd_none
7. pmd_bad
8. pmd_present
9. pmd_inuse
10. pmd_inuse
11. pmd_clear
12. pmd_reuse
13. pgd_none
14. pgd_bad
15. pgd_present
16. pgd_inuse
17. pgd_clear
18. pte_read
19. pte_write
20. pte_exec
21. pte_dirty
22. pte_young
23. pte_cow
24. pte_wrprotect
25. pte_rdprotect
26. pte_exprotect
27. pte_mkclean
28. pte_mkold
29. pte_uncow
30. pte_mkwrite
31. pte_mkread
32. pte_mkexec
33. pte_mkdirty
34. pte_mkyoung
35. pte_mkcow
36. mk_pte
37. pte_modify
38. pte_page
39. pmd_page
40. pgd_offset
41. pmd_offset
42. pte_offset
43. pte_free_kernel
44. pte_alloc_kernel
45. pmd_free_kernel
46. pmd_alloc_kernel
47. pte_free
48. pte_alloc
49. pmd_free
50. pmd_alloc
51. pgd_free
52. pgd_alloc
53. update_mmu_cache

   1 #ifndef _I386_PGTABLE_H
   2 #define _I386_PGTABLE_H
   3 
   4 /*
   5  * Define CONFIG_PENTIUM_MM if you want the 4MB page table optimizations.
   6  * This works only on a intel Pentium.
   7  */
   8 #define CONFIG_PENTIUM_MM 1
   9 
  10 /*
  11  * The Linux memory management assumes a three-level page table setup. On
  12  * the i386, we use that, but "fold" the mid level into the top-level page
  13  * table, so that we physically have the same two-level page table as the
  14  * i386 mmu expects.
  15  *
  16  * This file contains the functions and defines necessary to modify and use
  17  * the i386 page table tree.
  18  */
  19 
  20 /* PMD_SHIFT determines the size of the area a second-level page table can map */
  21 #define PMD_SHIFT       22
  22 #define PMD_SIZE        (1UL << PMD_SHIFT)
  23 #define PMD_MASK        (~(PMD_SIZE-1))
  24 
  25 /* PGDIR_SHIFT determines what a third-level page table entry can map */
  26 #define PGDIR_SHIFT     22
  27 #define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
  28 #define PGDIR_MASK      (~(PGDIR_SIZE-1))
  29 
  30 /*
  31  * entries per page directory level: the i386 is two-level, so
  32  * we don't really have any PMD directory physically.
  33  */
  34 #define PTRS_PER_PTE    1024
  35 #define PTRS_PER_PMD    1
  36 #define PTRS_PER_PGD    1024
  37 
  38 /* Just any arbitrary offset to the start of the vmalloc VM area: the
  39  * current 8MB value just means that there will be a 8MB "hole" after the
  40  * physical memory until the kernel virtual memory starts.  That means that
  41  * any out-of-bounds memory accesses will hopefully be caught.
  42  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
  43  * area for the same reason. ;)
  44  */
  45 #define VMALLOC_OFFSET  (8*1024*1024)
  46 #define VMALLOC_START ((high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
  47 #define VMALLOC_VMADDR(x) (TASK_SIZE + (unsigned long)(x))
  48 
  49 /*
  50  * The 4MB page is guessing..  Detailed in the infamous "Chapter H"
  51  * of the Pentium details, but assuming intel did the straigtforward
  52  * thing, this bit set in the page directory entry just means that
  53  * the page directory entry points directly to a 4MB-aligned block of
  54  * memory. 
  55  */
  56 #define _PAGE_PRESENT   0x001
  57 #define _PAGE_RW        0x002
  58 #define _PAGE_USER      0x004
  59 #define _PAGE_PCD       0x010
  60 #define _PAGE_ACCESSED  0x020
  61 #define _PAGE_DIRTY     0x040
  62 #define _PAGE_4M        0x080   /* 4 MB page, Pentium+.. */
  63 #define _PAGE_COW       0x200   /* implemented in software (one of the AVL bits) */
  64 
  65 #define _PAGE_TABLE     (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)
  66 #define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
  67 
  68 #define PAGE_NONE       __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED)
  69 #define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED)
  70 #define PAGE_COPY       __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_COW)
  71 #define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
  72 #define PAGE_KERNEL     __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
  73 
  74 /*
  75  * The i386 can't do page protection for execute, and considers that the same are read.
  76  * Also, write permissions imply read permissions. This is the closest we can get..
  77  */
  78 #define __P000  PAGE_NONE
  79 #define __P001  PAGE_READONLY
  80 #define __P010  PAGE_COPY
  81 #define __P011  PAGE_COPY
  82 #define __P100  PAGE_READONLY
  83 #define __P101  PAGE_READONLY
  84 #define __P110  PAGE_COPY
  85 #define __P111  PAGE_COPY
  86 
  87 #define __S000  PAGE_NONE
  88 #define __S001  PAGE_READONLY
  89 #define __S010  PAGE_SHARED
  90 #define __S011  PAGE_SHARED
  91 #define __S100  PAGE_READONLY
  92 #define __S101  PAGE_READONLY
  93 #define __S110  PAGE_SHARED
  94 #define __S111  PAGE_SHARED
  95 
  96 /*
  97  * Define this if things work differently on a i386 and a i486:
  98  * it will (on a i486) warn about kernel memory accesses that are
  99  * done without a 'verify_area(VERIFY_WRITE,..)'
 100  */
 101 #undef CONFIG_TEST_VERIFY_AREA
 102 
 103 /* page table for 0-4MB for everybody */
 104 extern unsigned long pg0[1024];
 105 /* zero page used for unitialized stuff */
 106 extern unsigned long empty_zero_page[1024];
 107 
 108 /*
 109  * BAD_PAGETABLE is used when we need a bogus page-table, while
 110  * BAD_PAGE is used for a bogus page.
 111  *
 112  * ZERO_PAGE is a global shared page that is always zero: used
 113  * for zero-mapped memory areas etc..
 114  */
 115 extern pte_t __bad_page(void);
 116 extern pte_t * __bad_pagetable(void);
 117 
 118 #define BAD_PAGETABLE __bad_pagetable()
 119 #define BAD_PAGE __bad_page()
 120 #define ZERO_PAGE ((unsigned long) empty_zero_page)
 121 
 122 /* number of bits that fit into a memory pointer */
 123 #define BITS_PER_PTR                    (8*sizeof(unsigned long))
 124 
 125 /* to align the pointer to a pointer address */
 126 #define PTR_MASK                        (~(sizeof(void*)-1))
 127 
 128 /* sizeof(void*)==1<<SIZEOF_PTR_LOG2 */
 129 /* 64-bit machines, beware!  SRB. */
 130 #define SIZEOF_PTR_LOG2                 2
 131 
 132 /* to find an entry in a page-table */
 133 #define PAGE_PTR(address) \
 134 ((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)
 135 
 136 /* to set the page-dir */
 137 #define SET_PAGE_DIR(tsk,pgdir) \
 138 do { \
 139         (tsk)->tss.cr3 = (unsigned long) (pgdir); \
 140         if ((tsk) == current) \
 141                 __asm__ __volatile__("movl %0,%%cr3": :"a" ((tsk)->tss.cr3)); \
 142 } while (0)
 143 
 144 extern inline int pte_none(pte_t pte)           { return !pte_val(pte); }
     /*  */
 145 extern inline int pte_present(pte_t pte)        { return pte_val(pte) & _PAGE_PRESENT; }
     /*  */
 146 extern inline int pte_inuse(pte_t *ptep)        { return mem_map[MAP_NR(ptep)].reserved || mem_map[MAP_NR(ptep)].count != 1; }
     /*  */
 147 extern inline void pte_clear(pte_t *ptep)       { pte_val(*ptep) = 0; }
     /*  */
 148 extern inline void pte_reuse(pte_t * ptep)
     /*  */
 149 {
 150         if (!mem_map[MAP_NR(ptep)].reserved)
 151                 mem_map[MAP_NR(ptep)].count++;
 152 }
 153 
 154 extern inline int pmd_none(pmd_t pmd)           { return !pmd_val(pmd); }
     /*  */
 155 extern inline int pmd_bad(pmd_t pmd)            { return (pmd_val(pmd) & ~PAGE_MASK) != _PAGE_TABLE || pmd_val(pmd) > high_memory; }
     /*  */
 156 extern inline int pmd_present(pmd_t pmd)        { return pmd_val(pmd) & _PAGE_PRESENT; }
     /*  */
 157 #ifdef CONFIG_PENTIUM_MM
 158 extern inline int pmd_inuse(pmd_t *pmdp)        { return (pmd_val(*pmdp) & _PAGE_4M) != 0; }
     /*  */
 159 #else
 160 extern inline int pmd_inuse(pmd_t *pmdp)        { return 0; }
     /*  */
 161 #endif
 162 extern inline void pmd_clear(pmd_t * pmdp)      { pmd_val(*pmdp) = 0; }
     /*  */
 163 extern inline void pmd_reuse(pmd_t * pmdp)      { }
     /*  */
 164 
 165 /*
 166  * The "pgd_xxx()" functions here are trivial for a folded two-level
 167  * setup: the pgd is never bad, and a pmd always exists (as it's folded
 168  * into the pgd entry)
 169  */
 170 extern inline int pgd_none(pgd_t pgd)           { return 0; }
     /*  */
 171 extern inline int pgd_bad(pgd_t pgd)            { return 0; }
     /*  */
 172 extern inline int pgd_present(pgd_t pgd)        { return 1; }
     /*  */
 173 extern inline int pgd_inuse(pgd_t * pgdp)       { return mem_map[MAP_NR(pgdp)].reserved; }
     /*  */
 174 extern inline void pgd_clear(pgd_t * pgdp)      { }
     /*  */
 175 
 176 /*
 177  * The following only work if pte_present() is true.
 178  * Undefined behaviour if not..
 179  */
 180 extern inline int pte_read(pte_t pte)           { return pte_val(pte) & _PAGE_USER; }
     /*  */
 181 extern inline int pte_write(pte_t pte)          { return pte_val(pte) & _PAGE_RW; }
     /*  */
 182 extern inline int pte_exec(pte_t pte)           { return pte_val(pte) & _PAGE_USER; }
     /*  */
 183 extern inline int pte_dirty(pte_t pte)          { return pte_val(pte) & _PAGE_DIRTY; }
     /*  */
 184 extern inline int pte_young(pte_t pte)          { return pte_val(pte) & _PAGE_ACCESSED; }
     /*  */
 185 extern inline int pte_cow(pte_t pte)            { return pte_val(pte) & _PAGE_COW; }
     /*  */
 186 
 187 extern inline pte_t pte_wrprotect(pte_t pte)    { pte_val(pte) &= ~_PAGE_RW; return pte; }
     /*  */
 188 extern inline pte_t pte_rdprotect(pte_t pte)    { pte_val(pte) &= ~_PAGE_USER; return pte; }
     /*  */
 189 extern inline pte_t pte_exprotect(pte_t pte)    { pte_val(pte) &= ~_PAGE_USER; return pte; }
     /*  */
 190 extern inline pte_t pte_mkclean(pte_t pte)      { pte_val(pte) &= ~_PAGE_DIRTY; return pte; }
     /*  */
 191 extern inline pte_t pte_mkold(pte_t pte)        { pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
     /*  */
 192 extern inline pte_t pte_uncow(pte_t pte)        { pte_val(pte) &= ~_PAGE_COW; return pte; }
     /*  */
 193 extern inline pte_t pte_mkwrite(pte_t pte)      { pte_val(pte) |= _PAGE_RW; return pte; }
     /*  */
 194 extern inline pte_t pte_mkread(pte_t pte)       { pte_val(pte) |= _PAGE_USER; return pte; }
     /*  */
 195 extern inline pte_t pte_mkexec(pte_t pte)       { pte_val(pte) |= _PAGE_USER; return pte; }
     /*  */
 196 extern inline pte_t pte_mkdirty(pte_t pte)      { pte_val(pte) |= _PAGE_DIRTY; return pte; }
     /*  */
 197 extern inline pte_t pte_mkyoung(pte_t pte)      { pte_val(pte) |= _PAGE_ACCESSED; return pte; }
     /*  */
 198 extern inline pte_t pte_mkcow(pte_t pte)        { pte_val(pte) |= _PAGE_COW; return pte; }
     /*  */
 199 
 200 /*
 201  * Conversion functions: convert a page and protection to a page entry,
 202  * and a page entry and page directory to the page they refer to.
 203  */
 204 extern inline pte_t mk_pte(unsigned long page, pgprot_t pgprot)
     /*  */
 205 { pte_t pte; pte_val(pte) = page | pgprot_val(pgprot); return pte; }
 206 
 207 extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
     /*  */
 208 { pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot); return pte; }
 209 
 210 extern inline unsigned long pte_page(pte_t pte)
     /*  */
 211 { return pte_val(pte) & PAGE_MASK; }
 212 
 213 extern inline unsigned long pmd_page(pmd_t pmd)
     /*  */
 214 { return pmd_val(pmd) & PAGE_MASK; }
 215 
 216 /* to find an entry in a page-table-directory */
 217 extern inline pgd_t * pgd_offset(struct mm_struct * mm, unsigned long address)
     /*  */
 218 {
 219         return mm->pgd + (address >> PGDIR_SHIFT);
 220 }
 221 
 222 /* Find an entry in the second-level page table.. */
 223 extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
     /*  */
 224 {
 225         return (pmd_t *) dir;
 226 }
 227 
 228 /* Find an entry in the third-level page table.. */ 
 229 extern inline pte_t * pte_offset(pmd_t * dir, unsigned long address)
     /*  */
 230 {
 231         return (pte_t *) pmd_page(*dir) + ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1));
 232 }
 233 
 234 /*
 235  * Allocate and free page tables. The xxx_kernel() versions are
 236  * used to allocate a kernel page table - this turns on ASN bits
 237  * if any, and marks the page tables reserved.
 238  */
 239 extern inline void pte_free_kernel(pte_t * pte)
     /*  */
 240 {
 241         mem_map[MAP_NR(pte)].reserved = 0;
 242         free_page((unsigned long) pte);
 243 }
 244 
 245 extern inline pte_t * pte_alloc_kernel(pmd_t * pmd, unsigned long address)
     /*  */
 246 {
 247         address = (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 248         if (pmd_none(*pmd)) {
 249                 pte_t * page = (pte_t *) get_free_page(GFP_KERNEL);
 250                 if (pmd_none(*pmd)) {
 251                         if (page) {
 252                                 pmd_val(*pmd) = _PAGE_TABLE | (unsigned long) page;
 253                                 mem_map[MAP_NR(page)].reserved = 1;
 254                                 return page + address;
 255                         }
 256                         pmd_val(*pmd) = _PAGE_TABLE | (unsigned long) BAD_PAGETABLE;
 257                         return NULL;
 258                 }
 259                 free_page((unsigned long) page);
 260         }
 261         if (pmd_bad(*pmd)) {
 262                 printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
 263                 pmd_val(*pmd) = _PAGE_TABLE | (unsigned long) BAD_PAGETABLE;
 264                 return NULL;
 265         }
 266         return (pte_t *) pmd_page(*pmd) + address;
 267 }
 268 
 269 /*
 270  * allocating and freeing a pmd is trivial: the 1-entry pmd is
 271  * inside the pgd, so has no extra memory associated with it.
 272  */
 273 extern inline void pmd_free_kernel(pmd_t * pmd)
     /*  */
 274 {
 275         pmd_val(*pmd) = 0;
 276 }
 277 
 278 extern inline pmd_t * pmd_alloc_kernel(pgd_t * pgd, unsigned long address)
     /*  */
 279 {
 280         return (pmd_t *) pgd;
 281 }
 282 
 283 extern inline void pte_free(pte_t * pte)
     /*  */
 284 {
 285         free_page((unsigned long) pte);
 286 }
 287 
 288 extern inline pte_t * pte_alloc(pmd_t * pmd, unsigned long address)
     /*  */
 289 {
 290         address = (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 291         if (pmd_none(*pmd)) {
 292                 pte_t * page = (pte_t *) get_free_page(GFP_KERNEL);
 293                 if (pmd_none(*pmd)) {
 294                         if (page) {
 295                                 pmd_val(*pmd) = _PAGE_TABLE | (unsigned long) page;
 296                                 return page + address;
 297                         }
 298                         pmd_val(*pmd) = _PAGE_TABLE | (unsigned long) BAD_PAGETABLE;
 299                         return NULL;
 300                 }
 301                 free_page((unsigned long) page);
 302         }
 303         if (pmd_bad(*pmd)) {
 304                 printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
 305                 pmd_val(*pmd) = _PAGE_TABLE | (unsigned long) BAD_PAGETABLE;
 306                 return NULL;
 307         }
 308         return (pte_t *) pmd_page(*pmd) + address;
 309 }
 310 
 311 /*
 312  * allocating and freeing a pmd is trivial: the 1-entry pmd is
 313  * inside the pgd, so has no extra memory associated with it.
 314  */
 315 extern inline void pmd_free(pmd_t * pmd)
     /*  */
 316 {
 317         pmd_val(*pmd) = 0;
 318 }
 319 
 320 extern inline pmd_t * pmd_alloc(pgd_t * pgd, unsigned long address)
     /*  */
 321 {
 322         return (pmd_t *) pgd;
 323 }
 324 
 325 extern inline void pgd_free(pgd_t * pgd)
     /*  */
 326 {
 327         free_page((unsigned long) pgd);
 328 }
 329 
 330 extern inline pgd_t * pgd_alloc(void)
     /*  */
 331 {
 332         return (pgd_t *) get_free_page(GFP_KERNEL);
 333 }
 334 
 335 extern pgd_t swapper_pg_dir[1024];
 336 
 337 /*
 338  * The i386 doesn't have any external MMU info: the kernel page
 339  * tables contain all the necessary information.
 340  */
 341 extern inline void update_mmu_cache(struct vm_area_struct * vma,
     /*  */
 342         unsigned long address, pte_t pte)
 343 {
 344 }
 345 
 346 #define SWP_TYPE(entry) (((entry) >> 1) & 0x7f)
 347 #define SWP_OFFSET(entry) ((entry) >> 8)
 348 #define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << 8))
 349 
 350 #endif /* _I386_PAGE_H */

/* */