root/include/asm-alpha/pgtable.h

/* */

INCLUDED FROM

DEFINITIONS

1. invalidate
2. invalidate_all
3. invalidate_mm
4. invalidate_page
5. invalidate_range
6. mk_pte
7. pte_modify
8. pmd_set
9. pgd_set
10. pte_page
11. pmd_page
12. pgd_page
13. pte_none
14. pte_present
15. pte_inuse
16. pte_clear
17. pte_reuse
18. pmd_none
19. pmd_bad
20. pmd_present
21. pmd_inuse
22. pmd_clear
23. pmd_reuse
24. pgd_none
25. pgd_bad
26. pgd_present
27. pgd_inuse
28. pgd_clear
29. pte_read
30. pte_write
31. pte_exec
32. pte_dirty
33. pte_young
34. pte_cow
35. pte_wrprotect
36. pte_rdprotect
37. pte_exprotect
38. pte_mkclean
39. pte_mkold
40. pte_uncow
41. pte_mkwrite
42. pte_mkread
43. pte_mkexec
44. pte_mkdirty
45. pte_mkyoung
46. pte_mkcow
47. SET_PAGE_DIR
48. pgd_offset
49. pmd_offset
50. pte_offset
51. pte_free_kernel
52. pte_alloc_kernel
53. pmd_free_kernel
54. pmd_alloc_kernel
55. pte_free
56. pte_alloc
57. pmd_free
58. pmd_alloc
59. pgd_free
60. pgd_alloc
61. update_mmu_cache
62. 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 extern void tbi(long type, ...);
  13 
  14 #define tbisi(x)        tbi(1,(x))
  15 #define tbisd(x)        tbi(2,(x))
  16 #define tbis(x)         tbi(3,(x))
  17 #define tbiap()         tbi(-1)
  18 #define tbia()          tbi(-2)
  19 
  20 /*
  21  * Invalidate current user mapping.
  22  */
  23 static inline void invalidate(void)
     /*  */
  24 {
  25         tbiap();
  26 }
  27 
  28 /*
  29  * Invalidate everything (kernel mapping may also have
  30  * changed due to vmalloc/vfree)
  31  */
  32 static inline void invalidate_all(void)
     /*  */
  33 {
  34         tbia();
  35 }
  36 
  37 /*
  38  * Invalidate a specified user mapping
  39  */
  40 static inline void invalidate_mm(struct mm_struct *mm)
     /*  */
  41 {
  42         tbiap();
  43 }
  44 
  45 /*
  46  * Page-granular invalidate.
  47  *
  48  * do a tbisd (type = 2) normally, and a tbis (type = 3)
  49  * if it is an executable mapping.  We want to avoid the
  50  * itlb invalidate, because that potentially also does a
  51  * icache invalidate. 
  52  */
  53 static inline void invalidate_page(struct vm_area_struct *vma,
     /*  */
  54         unsigned long addr)
  55 {
  56         tbi(2 + ((vma->vm_flags & VM_EXEC) != 0), addr);
  57 }
  58 
  59 /*
  60  * Invalidate a specified range of user mapping: on the
  61  * alpha we invalidate the whole user tlb
  62  */
  63 static inline void invalidate_range(struct mm_struct *mm,
     /*  */
  64         unsigned long start, unsigned long end)
  65 {
  66         tbiap();
  67 }
  68 
  69 /* Certain architectures need to do special things when pte's
  70  * within a page table are directly modified.  Thus, the following
  71  * hook is made available.
  72  */
  73 #define set_pte(pteptr, pteval) ((*(pteptr)) = (pteval))
  74 
  75 /* PMD_SHIFT determines the size of the area a second-level page table can map */
  76 #define PMD_SHIFT       (PAGE_SHIFT + (PAGE_SHIFT-3))
  77 #define PMD_SIZE        (1UL << PMD_SHIFT)
  78 #define PMD_MASK        (~(PMD_SIZE-1))
  79 
  80 /* PGDIR_SHIFT determines what a third-level page table entry can map */
  81 #define PGDIR_SHIFT     (PAGE_SHIFT + 2*(PAGE_SHIFT-3))
  82 #define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
  83 #define PGDIR_MASK      (~(PGDIR_SIZE-1))
  84 
  85 /*
  86  * entries per page directory level: the alpha is three-level, with
  87  * all levels having a one-page page table.
  88  *
  89  * The PGD is special: the last entry is reserved for self-mapping.
  90  */
  91 #define PTRS_PER_PTE    (1UL << (PAGE_SHIFT-3))
  92 #define PTRS_PER_PMD    (1UL << (PAGE_SHIFT-3))
  93 #define PTRS_PER_PGD    ((1UL << (PAGE_SHIFT-3))-1)
  94 
  95 /* the no. of pointers that fit on a page: this will go away */
  96 #define PTRS_PER_PAGE   (1UL << (PAGE_SHIFT-3))
  97 
  98 #define VMALLOC_START           0xFFFFFE0000000000
  99 #define VMALLOC_VMADDR(x)       ((unsigned long)(x))
 100 
 101 /*
 102  * OSF/1 PAL-code-imposed page table bits
 103  */
 104 #define _PAGE_VALID     0x0001
 105 #define _PAGE_FOR       0x0002  /* used for page protection (fault on read) */
 106 #define _PAGE_FOW       0x0004  /* used for page protection (fault on write) */
 107 #define _PAGE_FOE       0x0008  /* used for page protection (fault on exec) */
 108 #define _PAGE_ASM       0x0010
 109 #define _PAGE_KRE       0x0100  /* xxx - see below on the "accessed" bit */
 110 #define _PAGE_URE       0x0200  /* xxx */
 111 #define _PAGE_KWE       0x1000  /* used to do the dirty bit in software */
 112 #define _PAGE_UWE       0x2000  /* used to do the dirty bit in software */
 113 
 114 /* .. and these are ours ... */
 115 #define _PAGE_COW       0x10000
 116 #define _PAGE_DIRTY     0x20000
 117 #define _PAGE_ACCESSED  0x40000
 118 
 119 /*
 120  * NOTE! The "accessed" bit isn't necessarily exact: it can be kept exactly
 121  * by software (use the KRE/URE/KWE/UWE bits appropriately), but I'll fake it.
 122  * Under Linux/AXP, the "accessed" bit just means "read", and I'll just use
 123  * the KRE/URE bits to watch for it. That way we don't need to overload the
 124  * KWE/UWE bits with both handling dirty and accessed.
 125  *
 126  * Note that the kernel uses the accessed bit just to check whether to page
 127  * out a page or not, so it doesn't have to be exact anyway.
 128  */
 129 
 130 #define __DIRTY_BITS    (_PAGE_DIRTY | _PAGE_KWE | _PAGE_UWE)
 131 #define __ACCESS_BITS   (_PAGE_ACCESSED | _PAGE_KRE | _PAGE_URE)
 132 
 133 #define _PFN_MASK       0xFFFFFFFF00000000
 134 
 135 #define _PAGE_TABLE     (_PAGE_VALID | __DIRTY_BITS | __ACCESS_BITS)
 136 #define _PAGE_CHG_MASK  (_PFN_MASK | __DIRTY_BITS | __ACCESS_BITS)
 137 
 138 /*
 139  * All the normal masks have the "page accessed" bits on, as any time they are used,
 140  * the page is accessed. They are cleared only by the page-out routines
 141  */
 142 #define PAGE_NONE       __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOR | _PAGE_FOW | _PAGE_FOE)
 143 #define PAGE_SHARED     __pgprot(_PAGE_VALID | __ACCESS_BITS)
 144 #define PAGE_COPY       __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOW | _PAGE_COW)
 145 #define PAGE_READONLY   __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOW)
 146 #define PAGE_KERNEL     __pgprot(_PAGE_VALID | _PAGE_ASM | _PAGE_KRE | _PAGE_KWE)
 147 
 148 #define _PAGE_NORMAL(x) __pgprot(_PAGE_VALID | __ACCESS_BITS | (x))
 149 
 150 #define _PAGE_P(x) _PAGE_NORMAL((x) | (((x) & _PAGE_FOW)?0:(_PAGE_FOW | _PAGE_COW)))
 151 #define _PAGE_S(x) _PAGE_NORMAL(x)
 152 
 153 /*
 154  * The hardware can handle write-only mappings, but as the alpha
 155  * architecture does byte-wide writes with a read-modify-write
 156  * sequence, it's not practical to have write-without-read privs.
 157  * Thus the "-w- -> rw-" and "-wx -> rwx" mapping here (and in
 158  * arch/alpha/mm/fault.c)
 159  */
 160         /* xwr */
 161 #define __P000  _PAGE_P(_PAGE_FOE | _PAGE_FOW | _PAGE_FOR)
 162 #define __P001  _PAGE_P(_PAGE_FOE | _PAGE_FOW)
 163 #define __P010  _PAGE_P(_PAGE_FOE)
 164 #define __P011  _PAGE_P(_PAGE_FOE)
 165 #define __P100  _PAGE_P(_PAGE_FOW | _PAGE_FOR)
 166 #define __P101  _PAGE_P(_PAGE_FOW)
 167 #define __P110  _PAGE_P(0)
 168 #define __P111  _PAGE_P(0)
 169 
 170 #define __S000  _PAGE_S(_PAGE_FOE | _PAGE_FOW | _PAGE_FOR)
 171 #define __S001  _PAGE_S(_PAGE_FOE | _PAGE_FOW)
 172 #define __S010  _PAGE_S(_PAGE_FOE)
 173 #define __S011  _PAGE_S(_PAGE_FOE)
 174 #define __S100  _PAGE_S(_PAGE_FOW | _PAGE_FOR)
 175 #define __S101  _PAGE_S(_PAGE_FOW)
 176 #define __S110  _PAGE_S(0)
 177 #define __S111  _PAGE_S(0)
 178 
 179 /*
 180  * BAD_PAGETABLE is used when we need a bogus page-table, while
 181  * BAD_PAGE is used for a bogus page.
 182  *
 183  * ZERO_PAGE is a global shared page that is always zero: used
 184  * for zero-mapped memory areas etc..
 185  */
 186 extern pte_t __bad_page(void);
 187 extern pmd_t * __bad_pagetable(void);
 188 
 189 extern unsigned long __zero_page(void);
 190 
 191 #define BAD_PAGETABLE   __bad_pagetable()
 192 #define BAD_PAGE        __bad_page()
 193 #define ZERO_PAGE       0xfffffc000030A000
 194 
 195 /* number of bits that fit into a memory pointer */
 196 #define BITS_PER_PTR                    (8*sizeof(unsigned long))
 197 
 198 /* to align the pointer to a pointer address */
 199 #define PTR_MASK                        (~(sizeof(void*)-1))
 200 
 201 /* sizeof(void*)==1<<SIZEOF_PTR_LOG2 */
 202 #define SIZEOF_PTR_LOG2                 3
 203 
 204 /* to find an entry in a page-table */
 205 #define PAGE_PTR(address)               \
 206   ((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)
 207 
 208 extern unsigned long high_memory;
 209 
 210 /*
 211  * Conversion functions: convert a page and protection to a page entry,
 212  * and a page entry and page directory to the page they refer to.
 213  */
 214 extern inline pte_t mk_pte(unsigned long page, pgprot_t pgprot)
     /*  */
 215 { pte_t pte; pte_val(pte) = ((page-PAGE_OFFSET) << (32-PAGE_SHIFT)) | pgprot_val(pgprot); return pte; }
 216 
 217 extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
     /*  */
 218 { pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot); return pte; }
 219 
 220 extern inline void pmd_set(pmd_t * pmdp, pte_t * ptep)
     /*  */
 221 { pmd_val(*pmdp) = _PAGE_TABLE | ((((unsigned long) ptep) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }
 222 
 223 extern inline void pgd_set(pgd_t * pgdp, pmd_t * pmdp)
     /*  */
 224 { pgd_val(*pgdp) = _PAGE_TABLE | ((((unsigned long) pmdp) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }
 225 
 226 extern inline unsigned long pte_page(pte_t pte)
     /*  */
 227 { return PAGE_OFFSET + ((pte_val(pte) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
 228 
 229 extern inline unsigned long pmd_page(pmd_t pmd)
     /*  */
 230 { return PAGE_OFFSET + ((pmd_val(pmd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
 231 
 232 extern inline unsigned long pgd_page(pgd_t pgd)
     /*  */
 233 { return PAGE_OFFSET + ((pgd_val(pgd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
 234 
 235 extern inline int pte_none(pte_t pte)           { return !pte_val(pte); }
     /*  */
 236 extern inline int pte_present(pte_t pte)        { return pte_val(pte) & _PAGE_VALID; }
     /*  */
 237 extern inline int pte_inuse(pte_t *ptep)        { return mem_map[MAP_NR(ptep)].reserved || mem_map[MAP_NR(ptep)].count != 1; }
     /*  */
 238 extern inline void pte_clear(pte_t *ptep)       { pte_val(*ptep) = 0; }
     /*  */
 239 extern inline void pte_reuse(pte_t * ptep)
     /*  */
 240 {
 241         if (!mem_map[MAP_NR(ptep)].reserved)
 242                 mem_map[MAP_NR(ptep)].count++;
 243 }
 244 
 245 extern inline int pmd_none(pmd_t pmd)           { return !pmd_val(pmd); }
     /*  */
 246 extern inline int pmd_bad(pmd_t pmd)            { return (pmd_val(pmd) & ~_PFN_MASK) != _PAGE_TABLE || pmd_page(pmd) > high_memory; }
     /*  */
 247 extern inline int pmd_present(pmd_t pmd)        { return pmd_val(pmd) & _PAGE_VALID; }
     /*  */
 248 extern inline int pmd_inuse(pmd_t *pmdp)        { return mem_map[MAP_NR(pmdp)].reserved || mem_map[MAP_NR(pmdp)].count != 1; }
     /*  */
 249 extern inline void pmd_clear(pmd_t * pmdp)      { pmd_val(*pmdp) = 0; }
     /*  */
 250 extern inline void pmd_reuse(pmd_t * pmdp)
     /*  */
 251 {
 252         if (!mem_map[MAP_NR(pmdp)].reserved)
 253                 mem_map[MAP_NR(pmdp)].count++;
 254 }
 255 
 256 extern inline int pgd_none(pgd_t pgd)           { return !pgd_val(pgd); }
     /*  */
 257 extern inline int pgd_bad(pgd_t pgd)            { return (pgd_val(pgd) & ~_PFN_MASK) != _PAGE_TABLE || pgd_page(pgd) > high_memory; }
     /*  */
 258 extern inline int pgd_present(pgd_t pgd)        { return pgd_val(pgd) & _PAGE_VALID; }
     /*  */
 259 extern inline int pgd_inuse(pgd_t *pgdp)        { return mem_map[MAP_NR(pgdp)].reserved; }
     /*  */
 260 extern inline void pgd_clear(pgd_t * pgdp)      { pgd_val(*pgdp) = 0; }
     /*  */
 261 
 262 /*
 263  * The following only work if pte_present() is true.
 264  * Undefined behaviour if not..
 265  */
 266 extern inline int pte_read(pte_t pte)           { return !(pte_val(pte) & _PAGE_FOR); }
     /*  */
 267 extern inline int pte_write(pte_t pte)          { return !(pte_val(pte) & _PAGE_FOW); }
     /*  */
 268 extern inline int pte_exec(pte_t pte)           { return !(pte_val(pte) & _PAGE_FOE); }
     /*  */
 269 extern inline int pte_dirty(pte_t pte)          { return pte_val(pte) & _PAGE_DIRTY; }
     /*  */
 270 extern inline int pte_young(pte_t pte)          { return pte_val(pte) & _PAGE_ACCESSED; }
     /*  */
 271 extern inline int pte_cow(pte_t pte)            { return pte_val(pte) & _PAGE_COW; }
     /*  */
 272 
 273 extern inline pte_t pte_wrprotect(pte_t pte)    { pte_val(pte) |= _PAGE_FOW; return pte; }
     /*  */
 274 extern inline pte_t pte_rdprotect(pte_t pte)    { pte_val(pte) |= _PAGE_FOR; return pte; }
     /*  */
 275 extern inline pte_t pte_exprotect(pte_t pte)    { pte_val(pte) |= _PAGE_FOE; return pte; }
     /*  */
 276 extern inline pte_t pte_mkclean(pte_t pte)      { pte_val(pte) &= ~(__DIRTY_BITS); return pte; }
     /*  */
 277 extern inline pte_t pte_mkold(pte_t pte)        { pte_val(pte) &= ~(__ACCESS_BITS); return pte; }
     /*  */
 278 extern inline pte_t pte_uncow(pte_t pte)        { pte_val(pte) &= ~_PAGE_COW; return pte; }
     /*  */
 279 extern inline pte_t pte_mkwrite(pte_t pte)      { pte_val(pte) &= ~_PAGE_FOW; return pte; }
     /*  */
 280 extern inline pte_t pte_mkread(pte_t pte)       { pte_val(pte) &= ~_PAGE_FOR; return pte; }
     /*  */
 281 extern inline pte_t pte_mkexec(pte_t pte)       { pte_val(pte) &= ~_PAGE_FOE; return pte; }
     /*  */
 282 extern inline pte_t pte_mkdirty(pte_t pte)      { pte_val(pte) |= __DIRTY_BITS; return pte; }
     /*  */
 283 extern inline pte_t pte_mkyoung(pte_t pte)      { pte_val(pte) |= __ACCESS_BITS; return pte; }
     /*  */
 284 extern inline pte_t pte_mkcow(pte_t pte)        { pte_val(pte) |= _PAGE_COW; return pte; }
     /*  */
 285 
 286 /* 
 287  * To set the page-dir. Note the self-mapping in the last entry
 288  *
 289  * Also note that if we update the current process ptbr, we need to
 290  * update the PAL-cached ptbr value as well.. There doesn't seem to
 291  * be any "wrptbr" PAL-insn, but we can do a dummy swpctx to ourself
 292  * instead.
 293  */
 294 extern inline void SET_PAGE_DIR(struct task_struct * tsk, pgd_t * pgdir)
     /*  */
 295 {
 296         pgd_val(pgdir[PTRS_PER_PGD]) = pte_val(mk_pte((unsigned long) pgdir, PAGE_KERNEL));
 297         tsk->tss.ptbr = ((unsigned long) pgdir - PAGE_OFFSET) >> PAGE_SHIFT;
 298         if (tsk == current)
 299                 __asm__ __volatile__(
 300                         "bis %0,%0,$16\n\t"
 301                         "call_pal %1"
 302                         : /* no outputs */
 303                         : "r" (&tsk->tss), "i" (PAL_swpctx)
 304                         : "$0", "$1", "$16", "$22", "$23", "$24", "$25");
 305 }
 306 
 307 #define PAGE_DIR_OFFSET(tsk,address) pgd_offset((tsk),(address))
 308 
 309 /* to find an entry in a page-table-directory. */
 310 extern inline pgd_t * pgd_offset(struct mm_struct * mm, unsigned long address)
     /*  */
 311 {
 312         return mm->pgd + ((address >> PGDIR_SHIFT) & (PTRS_PER_PAGE - 1));
 313 }
 314 
 315 /* Find an entry in the second-level page table.. */
 316 extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
     /*  */
 317 {
 318         return (pmd_t *) pgd_page(*dir) + ((address >> PMD_SHIFT) & (PTRS_PER_PAGE - 1));
 319 }
 320 
 321 /* Find an entry in the third-level page table.. */
 322 extern inline pte_t * pte_offset(pmd_t * dir, unsigned long address)
     /*  */
 323 {
 324         return (pte_t *) pmd_page(*dir) + ((address >> PAGE_SHIFT) & (PTRS_PER_PAGE - 1));
 325 }
 326 
 327 /*      
 328  * Allocate and free page tables. The xxx_kernel() versions are
 329  * used to allocate a kernel page table - this turns on ASN bits
 330  * if any, and marks the page tables reserved.
 331  */
 332 extern inline void pte_free_kernel(pte_t * pte)
     /*  */
 333 {
 334         mem_map[MAP_NR(pte)].reserved = 0;
 335         free_page((unsigned long) pte);
 336 }
 337 
 338 extern inline pte_t * pte_alloc_kernel(pmd_t *pmd, unsigned long address)
     /*  */
 339 {
 340         address = (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 341         if (pmd_none(*pmd)) {
 342                 pte_t *page = (pte_t *) get_free_page(GFP_KERNEL);
 343                 if (pmd_none(*pmd)) {
 344                         if (page) {
 345                                 pmd_set(pmd, page);
 346                                 mem_map[MAP_NR(page)].reserved = 1;
 347                                 return page + address;
 348                         }
 349                         pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 350                         return NULL;
 351                 }
 352                 free_page((unsigned long) page);
 353         }
 354         if (pmd_bad(*pmd)) {
 355                 printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
 356                 pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 357                 return NULL;
 358         }
 359         return (pte_t *) pmd_page(*pmd) + address;
 360 }
 361 
 362 extern inline void pmd_free_kernel(pmd_t * pmd)
     /*  */
 363 {
 364         mem_map[MAP_NR(pmd)].reserved = 0;
 365         free_page((unsigned long) pmd);
 366 }
 367 
 368 extern inline pmd_t * pmd_alloc_kernel(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                                 mem_map[MAP_NR(page)].reserved = 1;
 377                                 return page + address;
 378                         }
 379                         pgd_set(pgd, BAD_PAGETABLE);
 380                         return NULL;
 381                 }
 382                 free_page((unsigned long) page);
 383         }
 384         if (pgd_bad(*pgd)) {
 385                 printk("Bad pgd in pmd_alloc: %08lx\n", pgd_val(*pgd));
 386                 pgd_set(pgd, BAD_PAGETABLE);
 387                 return NULL;
 388         }
 389         return (pmd_t *) pgd_page(*pgd) + address;
 390 }
 391 
 392 extern inline void pte_free(pte_t * pte)
     /*  */
 393 {
 394         free_page((unsigned long) pte);
 395 }
 396 
 397 extern inline pte_t * pte_alloc(pmd_t *pmd, unsigned long address)
     /*  */
 398 {
 399         address = (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
 400         if (pmd_none(*pmd)) {
 401                 pte_t *page = (pte_t *) get_free_page(GFP_KERNEL);
 402                 if (pmd_none(*pmd)) {
 403                         if (page) {
 404                                 pmd_set(pmd, page);
 405                                 return page + address;
 406                         }
 407                         pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 408                         return NULL;
 409                 }
 410                 free_page((unsigned long) page);
 411         }
 412         if (pmd_bad(*pmd)) {
 413                 printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
 414                 pmd_set(pmd, (pte_t *) BAD_PAGETABLE);
 415                 return NULL;
 416         }
 417         return (pte_t *) pmd_page(*pmd) + address;
 418 }
 419 
 420 extern inline void pmd_free(pmd_t * pmd)
     /*  */
 421 {
 422         free_page((unsigned long) pmd);
 423 }
 424 
 425 extern inline pmd_t * pmd_alloc(pgd_t *pgd, unsigned long address)
     /*  */
 426 {
 427         address = (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
 428         if (pgd_none(*pgd)) {
 429                 pmd_t *page = (pmd_t *) get_free_page(GFP_KERNEL);
 430                 if (pgd_none(*pgd)) {
 431                         if (page) {
 432                                 pgd_set(pgd, page);
 433                                 return page + address;
 434                         }
 435                         pgd_set(pgd, BAD_PAGETABLE);
 436                         return NULL;
 437                 }
 438                 free_page((unsigned long) page);
 439         }
 440         if (pgd_bad(*pgd)) {
 441                 printk("Bad pgd in pmd_alloc: %08lx\n", pgd_val(*pgd));
 442                 pgd_set(pgd, BAD_PAGETABLE);
 443                 return NULL;
 444         }
 445         return (pmd_t *) pgd_page(*pgd) + address;
 446 }
 447 
 448 extern inline void pgd_free(pgd_t * pgd)
     /*  */
 449 {
 450         free_page((unsigned long) pgd);
 451 }
 452 
 453 extern inline pgd_t * pgd_alloc(void)
     /*  */
 454 {
 455         return (pgd_t *) get_free_page(GFP_KERNEL);
 456 }
 457 
 458 extern pgd_t swapper_pg_dir[1024];
 459 
 460 /*
 461  * The alpha doesn't have any external MMU info: the kernel page
 462  * tables contain all the necessary information.
 463  */
 464 extern inline void update_mmu_cache(struct vm_area_struct * vma,
     /*  */
 465         unsigned long address, pte_t pte)
 466 {
 467 }
 468 
 469 /*
 470  * Non-present pages: high 24 bits are offset, next 8 bits type,
 471  * low 32 bits zero..
 472  */
 473 extern inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
     /*  */
 474 { pte_t pte; pte_val(pte) = (type << 32) | (offset << 40); return pte; }
 475 
 476 #define SWP_TYPE(entry) (((entry) >> 32) & 0xff)
 477 #define SWP_OFFSET(entry) ((entry) >> 40)
 478 #define SWP_ENTRY(type,offset) pte_val(mk_swap_pte((type),(offset)))
 479 
 480 #endif /* _ALPHA_PGTABLE_H */

/* */