root/include/asm-alpha/pgtable.h

/* */

INCLUDED FROM

DEFINITIONS

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

   1 #ifndef _ALPHA_PGTABLE_H
   2 #define _ALPHA_PGTABLE_H
   3 
   4 /*
   5  * This file contains the functions and defines necessary to modify and use
   6  * the alpha page table tree.
   7  *
   8  * This hopefully works with any standard alpha page-size, as defined
   9  * in <asm/page.h> (currently 8192).
  10  */
  11 
  12 /* PMD_SHIFT determines the size of the area a second-level page table can map */
  13 #define PMD_SHIFT       (PAGE_SHIFT + (PAGE_SHIFT-3))
  14 #define PMD_SIZE        (1UL << PMD_SHIFT)
  15 #define PMD_MASK        (~(PMD_SIZE-1))
  16 
  17 /* PGDIR_SHIFT determines what a third-level page table entry can map */
  18 #define PGDIR_SHIFT     (PAGE_SHIFT + 2*(PAGE_SHIFT-3))
  19 #define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
  20 #define PGDIR_MASK      (~(PGDIR_SIZE-1))
  21 
  22 /*
  23  * entries per page directory level: the alpha is three-level, with
  24  * all levels having a one-page page table.
  25  *
  26  * The PGD is special: the last entry is reserved for self-mapping.
  27  */
  28 #define PTRS_PER_PTE    (1UL << (PAGE_SHIFT-3))
  29 #define PTRS_PER_PMD    (1UL << (PAGE_SHIFT-3))
  30 #define PTRS_PER_PGD    ((1UL << (PAGE_SHIFT-3))-1)
  31 
  32 /* the no. of pointers that fit on a page: this will go away */
  33 #define PTRS_PER_PAGE   (1UL << (PAGE_SHIFT-3))
  34 
  35 #define VMALLOC_START           0xFFFFFE0000000000
  36 #define VMALLOC_VMADDR(x)       ((unsigned long)(x))
  37 
  38 /*
  39  * OSF/1 PAL-code-imposed page table bits
  40  */
  41 #define _PAGE_VALID     0x0001
  42 #define _PAGE_FOR       0x0002  /* used for page protection (fault on read) */
  43 #define _PAGE_FOW       0x0004  /* used for page protection (fault on write) */
  44 #define _PAGE_FOE       0x0008  /* used for page protection (fault on exec) */
  45 #define _PAGE_ASM       0x0010
  46 #define _PAGE_KRE       0x0100  /* xxx - see below on the "accessed" bit */
  47 #define _PAGE_URE       0x0200  /* xxx */
  48 #define _PAGE_KWE       0x1000  /* used to do the dirty bit in software */
  49 #define _PAGE_UWE       0x2000  /* used to do the dirty bit in software */
  50 
  51 /* .. and these are ours ... */
  52 #define _PAGE_COW       0x10000
  53 #define _PAGE_DIRTY     0x20000
  54 #define _PAGE_ACCESSED  0x40000
  55 
  56 /*
  57  * NOTE! The "accessed" bit isn't necessarily exact: it can be kept exactly
  58  * by software (use the KRE/URE/KWE/UWE bits appropriately), but I'll fake it.
  59  * Under Linux/AXP, the "accessed" bit just means "read", and I'll just use
  60  * the KRE/URE bits to watch for it. That way we don't need to overload the
  61  * KWE/UWE bits with both handling dirty and accessed.
  62  *
  63  * Note that the kernel uses the accessed bit just to check whether to page
  64  * out a page or not, so it doesn't have to be exact anyway.
  65  */
  66 
  67 #define __DIRTY_BITS    (_PAGE_DIRTY | _PAGE_KWE | _PAGE_UWE)
  68 #define __ACCESS_BITS   (_PAGE_ACCESSED | _PAGE_KRE | _PAGE_URE)
  69 
  70 #define _PFN_MASK       0xFFFFFFFF00000000
  71 
  72 #define _PAGE_TABLE     (_PAGE_VALID | __DIRTY_BITS | __ACCESS_BITS)
  73 #define _PAGE_CHG_MASK  (_PFN_MASK | __DIRTY_BITS | __ACCESS_BITS)
  74 
  75 /*
  76  * All the normal masks have the "page accessed" bits on, as any time they are used,
  77  * the page is accessed. They are cleared only by the page-out routines
  78  */
  79 #define PAGE_NONE       __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOR | _PAGE_FOW | _PAGE_FOE)
  80 #define PAGE_SHARED     __pgprot(_PAGE_VALID | __ACCESS_BITS)
  81 #define PAGE_COPY       __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOW | _PAGE_COW)
  82 #define PAGE_READONLY   __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOW)
  83 #define PAGE_KERNEL     __pgprot(_PAGE_VALID | _PAGE_ASM | _PAGE_KRE | _PAGE_KWE)
  84 
  85 #define _PAGE_NORMAL(x) __pgprot(_PAGE_VALID | __ACCESS_BITS | (x))
  86 
  87 #define _PAGE_P(x) _PAGE_NORMAL((x) | (((x) & _PAGE_FOW)?0:(_PAGE_FOW | _PAGE_COW)))
  88 #define _PAGE_S(x) _PAGE_NORMAL(x)
  89 
  90 /*
  91  * The hardware can handle write-only mappings, but as the alpha
  92  * architecture does byte-wide writes with a read-modify-write
  93  * sequence, it's not practical to have write-without-read privs.
  94  * Thus the "-w- -> rw-" and "-wx -> rwx" mapping here (and in
  95  * arch/alpha/mm/fault.c)
  96  */
  97         /* xwr */
  98 #define __P000  _PAGE_P(_PAGE_FOE | _PAGE_FOW | _PAGE_FOR)
  99 #define __P001  _PAGE_P(_PAGE_FOE | _PAGE_FOW)
 100 #define __P010  _PAGE_P(_PAGE_FOE)
 101 #define __P011  _PAGE_P(_PAGE_FOE)
 102 #define __P100  _PAGE_P(_PAGE_FOW | _PAGE_FOR)
 103 #define __P101  _PAGE_P(_PAGE_FOW)
 104 #define __P110  _PAGE_P(0)
 105 #define __P111  _PAGE_P(0)
 106 
 107 #define __S000  _PAGE_S(_PAGE_FOE | _PAGE_FOW | _PAGE_FOR)
 108 #define __S001  _PAGE_S(_PAGE_FOE | _PAGE_FOW)
 109 #define __S010  _PAGE_S(_PAGE_FOE)
 110 #define __S011  _PAGE_S(_PAGE_FOE)
 111 #define __S100  _PAGE_S(_PAGE_FOW | _PAGE_FOR)
 112 #define __S101  _PAGE_S(_PAGE_FOW)
 113 #define __S110  _PAGE_S(0)
 114 #define __S111  _PAGE_S(0)
 115 
 116 /*
 117  * BAD_PAGETABLE is used when we need a bogus page-table, while
 118  * BAD_PAGE is used for a bogus page.
 119  *
 120  * ZERO_PAGE is a global shared page that is always zero: used
 121  * for zero-mapped memory areas etc..
 122  */
 123 extern pte_t __bad_page(void);
 124 extern pmd_t * __bad_pagetable(void);
 125 
 126 extern unsigned long __zero_page(void);
 127 
 128 #define BAD_PAGETABLE __bad_pagetable()
 129 #define BAD_PAGE __bad_page()
 130 #define ZERO_PAGE __zero_page()
 131 
 132 /* number of bits that fit into a memory pointer */
 133 #define BITS_PER_PTR                    (8*sizeof(unsigned long))
 134 
 135 /* to align the pointer to a pointer address */
 136 #define PTR_MASK                        (~(sizeof(void*)-1))
 137 
 138 /* sizeof(void*)==1<<SIZEOF_PTR_LOG2 */
 139 #define SIZEOF_PTR_LOG2                 3
 140 
 141 /* to find an entry in a page-table */
 142 #define PAGE_PTR(address)               \
 143   ((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)
 144 
 145 extern unsigned long high_memory;
 146 
 147 /*
 148  * Conversion functions: convert a page and protection to a page entry,
 149  * and a page entry and page directory to the page they refer to.
 150  */
 151 extern inline pte_t mk_pte(unsigned long page, pgprot_t pgprot)
     /*  */
 152 { pte_t pte; pte_val(pte) = ((page-PAGE_OFFSET) << (32-PAGE_SHIFT)) | pgprot_val(pgprot); return pte; }
 153 
 154 extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
     /*  */
 155 { pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot); return pte; }
 156 
 157 extern inline void pmd_set(pmd_t * pmdp, pte_t * ptep)
     /*  */
 158 { pmd_val(*pmdp) = _PAGE_TABLE | ((((unsigned long) ptep) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }
 159 
 160 extern inline void pgd_set(pgd_t * pgdp, pmd_t * pmdp)
     /*  */
 161 { pgd_val(*pgdp) = _PAGE_TABLE | ((((unsigned long) pmdp) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }
 162 
 163 extern inline unsigned long pte_page(pte_t pte)
     /*  */
 164 { return PAGE_OFFSET + ((pte_val(pte) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
 165 
 166 extern inline unsigned long pmd_page(pmd_t pmd)
     /*  */
 167 { return PAGE_OFFSET + ((pmd_val(pmd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
 168 
 169 extern inline unsigned long pgd_page(pgd_t pgd)
     /*  */
 170 { return PAGE_OFFSET + ((pgd_val(pgd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
 171 
 172 extern inline int pte_none(pte_t pte)           { return !pte_val(pte); }
     /*  */
 173 extern inline int pte_present(pte_t pte)        { return pte_val(pte) & _PAGE_VALID; }
     /*  */
 174 extern inline int pte_inuse(pte_t *ptep)        { return mem_map[MAP_NR(ptep)] != 1; }
     /*  */
 175 extern inline void pte_clear(pte_t *ptep)       { pte_val(*ptep) = 0; }
     /*  */
 176 extern inline void pte_reuse(pte_t * ptep)
     /*  */
 177 {
 178         if (!(mem_map[MAP_NR(ptep)] & MAP_PAGE_RESERVED))
 179                 mem_map[MAP_NR(ptep)]++;
 180 }
 181 
 182 extern inline int pmd_none(pmd_t pmd)           { return !pmd_val(pmd); }
     /*  */
 183 extern inline int pmd_bad(pmd_t pmd)            { return (pmd_val(pmd) & ~_PFN_MASK) != _PAGE_TABLE || pmd_page(pmd) > high_memory; }
     /*  */
 184 extern inline int pmd_present(pmd_t pmd)        { return pmd_val(pmd) & _PAGE_VALID; }
     /*  */
 185 extern inline int pmd_inuse(pmd_t *pmdp)        { return mem_map[MAP_NR(pmdp)] != 1; }
     /*  */
 186 extern inline void pmd_clear(pmd_t * pmdp)      { pmd_val(*pmdp) = 0; }
     /*  */
 187 extern inline void pmd_reuse(pmd_t * pmdp)
     /*  */
 188 {
 189         if (!(mem_map[MAP_NR(pmdp)] & MAP_PAGE_RESERVED))
 190                 mem_map[MAP_NR(pmdp)]++;
 191 }
 192 
 193 extern inline int pgd_none(pgd_t pgd)           { return !pgd_val(pgd); }
     /*  */
 194 extern inline int pgd_bad(pgd_t pgd)            { return (pgd_val(pgd) & ~_PFN_MASK) != _PAGE_TABLE || pgd_page(pgd) > high_memory; }
     /*  */
 195 extern inline int pgd_present(pgd_t pgd)        { return pgd_val(pgd) & _PAGE_VALID; }
     /*  */
 196 extern inline int pgd_inuse(pgd_t *pgdp)        { return mem_map[MAP_NR(pgdp)] != 1; }
     /*  */
 197 extern inline void pgd_clear(pgd_t * pgdp)      { pgd_val(*pgdp) = 0; }
     /*  */
 198 extern inline void pgd_reuse(pgd_t * pgdp)
     /*  */
 199 {
 200         if (!(mem_map[MAP_NR(pgdp)] & MAP_PAGE_RESERVED))
 201                 mem_map[MAP_NR(pgdp)]++;
 202 }
 203 
 204 /*
 205  * The following only work if pte_present() is true.
 206  * Undefined behaviour if not..
 207  */
 208 extern inline int pte_read(pte_t pte)           { return !(pte_val(pte) & _PAGE_FOR); }
     /*  */
 209 extern inline int pte_write(pte_t pte)          { return !(pte_val(pte) & _PAGE_FOW); }
     /*  */
 210 extern inline int pte_exec(pte_t pte)           { return !(pte_val(pte) & _PAGE_FOE); }
     /*  */
 211 extern inline int pte_dirty(pte_t pte)          { return pte_val(pte) & _PAGE_DIRTY; }
     /*  */
 212 extern inline int pte_young(pte_t pte)          { return pte_val(pte) & _PAGE_ACCESSED; }
     /*  */
 213 extern inline int pte_cow(pte_t pte)            { return pte_val(pte) & _PAGE_COW; }
     /*  */
 214 
 215 extern inline pte_t pte_wrprotect(pte_t pte)    { pte_val(pte) |= _PAGE_FOW; return pte; }
     /*  */
 216 extern inline pte_t pte_rdprotect(pte_t pte)    { pte_val(pte) |= _PAGE_FOR; return pte; }
     /*  */
 217 extern inline pte_t pte_exprotect(pte_t pte)    { pte_val(pte) |= _PAGE_FOE; return pte; }
     /*  */
 218 extern inline pte_t pte_mkclean(pte_t pte)      { pte_val(pte) &= ~(__DIRTY_BITS); return pte; }
     /*  */
 219 extern inline pte_t pte_mkold(pte_t pte)        { pte_val(pte) &= ~(__ACCESS_BITS); return pte; }
     /*  */
 220 extern inline pte_t pte_uncow(pte_t pte)        { pte_val(pte) &= ~_PAGE_COW; return pte; }
     /*  */
 221 extern inline pte_t pte_mkwrite(pte_t pte)      { pte_val(pte) &= ~_PAGE_FOW; return pte; }
     /*  */
 222 extern inline pte_t pte_mkread(pte_t pte)       { pte_val(pte) &= ~_PAGE_FOR; return pte; }
     /*  */
 223 extern inline pte_t pte_mkexec(pte_t pte)       { pte_val(pte) &= ~_PAGE_FOE; return pte; }
     /*  */
 224 extern inline pte_t pte_mkdirty(pte_t pte)      { pte_val(pte) |= __DIRTY_BITS; return pte; }
     /*  */
 225 extern inline pte_t pte_mkyoung(pte_t pte)      { pte_val(pte) |= __ACCESS_BITS; return pte; }
     /*  */
 226 extern inline pte_t pte_mkcow(pte_t pte)        { pte_val(pte) |= _PAGE_COW; return pte; }
     /*  */
 227 
 228 /* 
 229  * To set the page-dir. Note the self-mapping in the last entry
 230  *
 231  * Also note that if we update the current process ptbr, we need to
 232  * update the PAL-cached ptbr value as well.. There doesn't seem to
 233  * be any "wrptbr" PAL-insn, but we can do a dummy swpctx to ourself
 234  * instead.
 235  */
 236 extern inline void SET_PAGE_DIR(struct task_struct * tsk, pgd_t * pgdir)
     /*  */
 237 {
 238         pgd_val(pgdir[PTRS_PER_PGD]) = pte_val(mk_pte((unsigned long) pgdir, PAGE_KERNEL));
 239         tsk->tss.ptbr = ((unsigned long) pgdir - PAGE_OFFSET) >> PAGE_SHIFT;
 240         if (tsk == current)
 241                 __asm__ __volatile__(
 242                         "bis %0,%0,$16\n\t"
 243                         "call_pal %1"
 244                         : /* no outputs */
 245                         : "r" (&tsk->tss), "i" (PAL_swpctx)
 246                         : "$0", "$1", "$16", "$22", "$23", "$24", "$25");
 247 }
 248 
 249 #define PAGE_DIR_OFFSET(tsk,address) pgd_offset((tsk),(address))
 250 
 251 /* to find an entry in a page-table-directory. */
 252 extern inline pgd_t * pgd_offset(struct task_struct * tsk, unsigned long address)
     /*  */
 253 {
 254         return (pgd_t *) ((tsk->tss.ptbr << PAGE_SHIFT) + PAGE_OFFSET) +
 255                 ((address >> PGDIR_SHIFT) & (PTRS_PER_PAGE - 1));
 256 }
 257 
 258 /* Find an entry in the second-level page table.. */
 259 extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
     /*  */
 260 {
 261         return (pmd_t *) pgd_page(*dir) + ((address >> PMD_SHIFT) & (PTRS_PER_PAGE - 1));
 262 }
 263 
 264 /* Find an entry in the third-level page table.. */
 265 extern inline pte_t * pte_offset(pmd_t * dir, unsigned long address)
     /*  */
 266 {
 267         return (pte_t *) pmd_page(*dir) + ((address >> PAGE_SHIFT) & (PTRS_PER_PAGE - 1));
 268 }
 269 
 270 /*      
 271  * Allocate and free page tables. The xxx_kernel() versions are
 272  * used to allocate a kernel page table - this turns on ASN bits
 273  * if any, and marks the page tables reserved.
 274  */
 275 extern inline void pte_free_kernel(pte_t * pte)
     /*  */
 276 {
 277         mem_map[MAP_NR(pte)] = 1;
 278         free_page((unsigned long) pte);
 279 }
 280 
 281 extern inline pte_t * pte_alloc_kernel(pmd_t *pmd, unsigned long address)
     /*  */
 282 {
 283         address = (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 284         if (pmd_none(*pmd)) {
 285                 pte_t *page = (pte_t *) get_free_page(GFP_KERNEL);
 286                 if (pmd_none(*pmd)) {
 287                         if (page) {
 288                                 pmd_set(pmd, page);
 289                                 mem_map[MAP_NR(page)] = MAP_PAGE_RESERVED;
 290                                 return page + address;
 291                         }
 292                         pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 293                         return NULL;
 294                 }
 295                 free_page((unsigned long) page);
 296         }
 297         if (pmd_bad(*pmd)) {
 298                 printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
 299                 pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 300                 return NULL;
 301         }
 302         return (pte_t *) pmd_page(*pmd) + address;
 303 }
 304 
 305 extern inline void pmd_free_kernel(pmd_t * pmd)
     /*  */
 306 {
 307         mem_map[MAP_NR(pmd)] = 1;
 308         free_page((unsigned long) pmd);
 309 }
 310 
 311 extern inline pmd_t * pmd_alloc_kernel(pgd_t *pgd, unsigned long address)
     /*  */
 312 {
 313         address = (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
 314         if (pgd_none(*pgd)) {
 315                 pmd_t *page = (pmd_t *) get_free_page(GFP_KERNEL);
 316                 if (pgd_none(*pgd)) {
 317                         if (page) {
 318                                 pgd_set(pgd, page);
 319                                 mem_map[MAP_NR(page)] = MAP_PAGE_RESERVED;
 320                                 return page + address;
 321                         }
 322                         pgd_set(pgd, BAD_PAGETABLE);
 323                         return NULL;
 324                 }
 325                 free_page((unsigned long) page);
 326         }
 327         if (pgd_bad(*pgd)) {
 328                 printk("Bad pgd in pmd_alloc: %08lx\n", pgd_val(*pgd));
 329                 pgd_set(pgd, BAD_PAGETABLE);
 330                 return NULL;
 331         }
 332         return (pmd_t *) pgd_page(*pgd) + address;
 333 }
 334 
 335 extern inline void pte_free(pte_t * pte)
     /*  */
 336 {
 337         free_page((unsigned long) pte);
 338 }
 339 
 340 extern inline pte_t * pte_alloc(pmd_t *pmd, unsigned long address)
     /*  */
 341 {
 342         address = (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 343         if (pmd_none(*pmd)) {
 344                 pte_t *page = (pte_t *) get_free_page(GFP_KERNEL);
 345                 if (pmd_none(*pmd)) {
 346                         if (page) {
 347                                 pmd_set(pmd, page);
 348                                 return page + address;
 349                         }
 350                         pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 351                         return NULL;
 352                 }
 353                 free_page((unsigned long) page);
 354         }
 355         if (pmd_bad(*pmd)) {
 356                 printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
 357                 pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 358                 return NULL;
 359         }
 360         return (pte_t *) pmd_page(*pmd) + address;
 361 }
 362 
 363 extern inline void pmd_free(pmd_t * pmd)
     /*  */
 364 {
 365         free_page((unsigned long) pmd);
 366 }
 367 
 368 extern inline pmd_t * pmd_alloc(pgd_t *pgd, unsigned long address)
     /*  */
 369 {
 370         address = (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
 371         if (pgd_none(*pgd)) {
 372                 pmd_t *page = (pmd_t *) get_free_page(GFP_KERNEL);
 373                 if (pgd_none(*pgd)) {
 374                         if (page) {
 375                                 pgd_set(pgd, page);
 376                                 return page + address;
 377                         }
 378                         pgd_set(pgd, BAD_PAGETABLE);
 379                         return NULL;
 380                 }
 381                 free_page((unsigned long) page);
 382         }
 383         if (pgd_bad(*pgd)) {
 384                 printk("Bad pgd in pmd_alloc: %08lx\n", pgd_val(*pgd));
 385                 pgd_set(pgd, BAD_PAGETABLE);
 386                 return NULL;
 387         }
 388         return (pmd_t *) pgd_page(*pgd) + address;
 389 }
 390 
 391 extern inline void pgd_free(pgd_t * pgd)
     /*  */
 392 {
 393         free_page((unsigned long) pgd);
 394 }
 395 
 396 extern inline pgd_t * pgd_alloc(void)
     /*  */
 397 {
 398         return (pgd_t *) get_free_page(GFP_KERNEL);
 399 }
 400 
 401 extern pgd_t swapper_pg_dir[1024];
 402 
 403 /*
 404  * The alpha doesn't have any external MMU info: the kernel page
 405  * tables contain all the necessary information.
 406  */
 407 extern inline void update_mmu_cache(struct vm_area_struct * vma,
     /*  */
 408         unsigned long address, pte_t pte)
 409 {
 410 }
 411 
 412 /*
 413  * Non-present pages: high 24 bits are offset, next 8 bits type,
 414  * low 32 bits zero..
 415  */
 416 extern inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
     /*  */
 417 { pte_t pte; pte_val(pte) = (type << 32) | (offset << 40); return pte; }
 418 
 419 #define SWP_TYPE(entry) (((entry) >> 32) & 0xff)
 420 #define SWP_OFFSET(entry) ((entry) >> 40)
 421 #define SWP_ENTRY(type,offset) pte_val(mk_swap_pte((type),(offset)))
 422 
 423 #endif /* _ALPHA_PGTABLE_H */

/* */