include/asm-powerpc/pgtable-ppc64.h

   1 #ifndef _ASM_POWERPC_PGTABLE_PPC64_H_
   2 #define _ASM_POWERPC_PGTABLE_PPC64_H_
   3 /*
   4  * This file contains the functions and defines necessary to modify and use
   5  * the ppc64 hashed page table.
   6  */
   7
   8 #ifndef __ASSEMBLY__
   9 #include <linux/stddef.h>
  10 #include <asm/processor.h>              /* For TASK_SIZE */
  11 #include <asm/mmu.h>
  12 #include <asm/page.h>
  13 #include <asm/tlbflush.h>
  14 struct mm_struct;
  15 #endif /* __ASSEMBLY__ */
  16
  17 #ifdef CONFIG_PPC_64K_PAGES
  18 #include <asm/pgtable-64k.h>
  19 #else
  20 #include <asm/pgtable-4k.h>
  21 #endif
  22
  23 #define FIRST_USER_ADDRESS      0
  24
  25 /*
  26  * Size of EA range mapped by our pagetables.
  27  */
  28 #define PGTABLE_EADDR_SIZE (PTE_INDEX_SIZE + PMD_INDEX_SIZE + \
  29                             PUD_INDEX_SIZE + PGD_INDEX_SIZE + PAGE_SHIFT)
  30 #define PGTABLE_RANGE (ASM_CONST(1) << PGTABLE_EADDR_SIZE)
  31
  32 #if TASK_SIZE_USER64 > PGTABLE_RANGE
  33 #error TASK_SIZE_USER64 exceeds pagetable range
  34 #endif
  35
  36 #if TASK_SIZE_USER64 > (1UL << (USER_ESID_BITS + SID_SHIFT))
  37 #error TASK_SIZE_USER64 exceeds user VSID range
  38 #endif
  39
  40
  41 /*
  42  * Define the address range of the vmalloc VM area.
  43  */
  44 #define VMALLOC_START ASM_CONST(0xD000000000000000)
  45 #define VMALLOC_SIZE  (PGTABLE_RANGE >> 1)
  46 #define VMALLOC_END   (VMALLOC_START + VMALLOC_SIZE)
  47
  48 /*
  49  * Define the address ranges for MMIO and IO space :
  50  *
  51  *  ISA_IO_BASE = VMALLOC_END, 64K reserved area
  52  *  PHB_IO_BASE = ISA_IO_BASE + 64K to ISA_IO_BASE + 2G, PHB IO spaces
  53  * IOREMAP_BASE = ISA_IO_BASE + 2G to VMALLOC_START + PGTABLE_RANGE
  54  */
  55 #define FULL_IO_SIZE    0x80000000ul
  56 #define  ISA_IO_BASE    (VMALLOC_END)
  57 #define  ISA_IO_END     (VMALLOC_END + 0x10000ul)
  58 #define  PHB_IO_BASE    (ISA_IO_END)
  59 #define  PHB_IO_END     (VMALLOC_END + FULL_IO_SIZE)
  60 #define IOREMAP_BASE    (PHB_IO_END)
  61 #define IOREMAP_END     (VMALLOC_START + PGTABLE_RANGE)
  62
  63 /*
  64  * Region IDs
  65  */
  66 #define REGION_SHIFT            60UL
  67 #define REGION_MASK             (0xfUL << REGION_SHIFT)
  68 #define REGION_ID(ea)           (((unsigned long)(ea)) >> REGION_SHIFT)
  69
  70 #define VMALLOC_REGION_ID       (REGION_ID(VMALLOC_START))
  71 #define KERNEL_REGION_ID        (REGION_ID(PAGE_OFFSET))
  72 #define USER_REGION_ID          (0UL)
  73
  74 /*
  75  * Common bits in a linux-style PTE.  These match the bits in the
  76  * (hardware-defined) PowerPC PTE as closely as possible. Additional
  77  * bits may be defined in pgtable-*.h
  78  */
  79 #define _PAGE_PRESENT   0x0001 /* software: pte contains a translation */
  80 #define _PAGE_USER      0x0002 /* matches one of the PP bits */
  81 #define _PAGE_FILE      0x0002 /* (!present only) software: pte holds file offset */
  82 #define _PAGE_EXEC      0x0004 /* No execute on POWER4 and newer (we invert) */
  83 #define _PAGE_GUARDED   0x0008
  84 #define _PAGE_COHERENT  0x0010 /* M: enforce memory coherence (SMP systems) */
  85 #define _PAGE_NO_CACHE  0x0020 /* I: cache inhibit */
  86 #define _PAGE_WRITETHRU 0x0040 /* W: cache write-through */
  87 #define _PAGE_DIRTY     0x0080 /* C: page changed */
  88 #define _PAGE_ACCESSED  0x0100 /* R: page referenced */
  89 #define _PAGE_RW        0x0200 /* software: user write access allowed */
  90 #define _PAGE_HASHPTE   0x0400 /* software: pte has an associated HPTE */
  91 #define _PAGE_BUSY      0x0800 /* software: PTE & hash are busy */
  92
  93 #define _PAGE_BASE      (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_COHERENT)
  94
  95 #define _PAGE_WRENABLE  (_PAGE_RW | _PAGE_DIRTY)
  96
  97 /* __pgprot defined in asm-powerpc/page.h */
  98 #define PAGE_NONE       __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED)
  99
 100 #define PAGE_SHARED     __pgprot(_PAGE_BASE | _PAGE_RW | _PAGE_USER)
 101 #define PAGE_SHARED_X   __pgprot(_PAGE_BASE | _PAGE_RW | _PAGE_USER | _PAGE_EXEC)
 102 #define PAGE_COPY       __pgprot(_PAGE_BASE | _PAGE_USER)
 103 #define PAGE_COPY_X     __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
 104 #define PAGE_READONLY   __pgprot(_PAGE_BASE | _PAGE_USER)
 105 #define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
 106 #define PAGE_KERNEL     __pgprot(_PAGE_BASE | _PAGE_WRENABLE)
 107 #define PAGE_KERNEL_CI  __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
 108                                _PAGE_WRENABLE | _PAGE_NO_CACHE | _PAGE_GUARDED)
 109 #define PAGE_KERNEL_EXEC __pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_EXEC)
 110
 111 #define PAGE_AGP        __pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_NO_CACHE)
 112 #define HAVE_PAGE_AGP
 113
 114 /* PTEIDX nibble */
 115 #define _PTEIDX_SECONDARY       0x8
 116 #define _PTEIDX_GROUP_IX        0x7
 117
 118
 119 /*
 120  * POWER4 and newer have per page execute protection, older chips can only
 121  * do this on a segment (256MB) basis.
 122  *
 123  * Also, write permissions imply read permissions.
 124  * This is the closest we can get..
 125  *
 126  * Note due to the way vm flags are laid out, the bits are XWR
 127  */
 128 #define __P000  PAGE_NONE
 129 #define __P001  PAGE_READONLY
 130 #define __P010  PAGE_COPY
 131 #define __P011  PAGE_COPY
 132 #define __P100  PAGE_READONLY_X
 133 #define __P101  PAGE_READONLY_X
 134 #define __P110  PAGE_COPY_X
 135 #define __P111  PAGE_COPY_X
 136
 137 #define __S000  PAGE_NONE
 138 #define __S001  PAGE_READONLY
 139 #define __S010  PAGE_SHARED
 140 #define __S011  PAGE_SHARED
 141 #define __S100  PAGE_READONLY_X
 142 #define __S101  PAGE_READONLY_X
 143 #define __S110  PAGE_SHARED_X
 144 #define __S111  PAGE_SHARED_X
 145
 146 #ifndef __ASSEMBLY__
 147
 148 /*
 149  * ZERO_PAGE is a global shared page that is always zero: used
 150  * for zero-mapped memory areas etc..
 151  */
 152 extern unsigned long empty_zero_page[PAGE_SIZE/sizeof(unsigned long)];
 153 #define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
 154 #endif /* __ASSEMBLY__ */
 155
 156 #ifdef CONFIG_HUGETLB_PAGE
 157
 158 #define HAVE_ARCH_UNMAPPED_AREA
 159 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
 160
 161 #endif
 162
 163 #ifndef __ASSEMBLY__
 164
 165 /*
 166  * Conversion functions: convert a page and protection to a page entry,
 167  * and a page entry and page directory to the page they refer to.
 168  *
 169  * mk_pte takes a (struct page *) as input
 170  */
 171 #define mk_pte(page, pgprot)    pfn_pte(page_to_pfn(page), (pgprot))
 172
 173 static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot)
 174 {
 175         pte_t pte;
 176
 177
 178         pte_val(pte) = (pfn << PTE_RPN_SHIFT) | pgprot_val(pgprot);
 179         return pte;
 180 }
 181
 182 #define pte_modify(_pte, newprot) \
 183   (__pte((pte_val(_pte) & _PAGE_CHG_MASK) | pgprot_val(newprot)))
 184
 185 #define pte_none(pte)           ((pte_val(pte) & ~_PAGE_HPTEFLAGS) == 0)
 186 #define pte_present(pte)        (pte_val(pte) & _PAGE_PRESENT)
 187
 188 /* pte_clear moved to later in this file */
 189
 190 #define pte_pfn(x)              ((unsigned long)((pte_val(x)>>PTE_RPN_SHIFT)))
 191 #define pte_page(x)             pfn_to_page(pte_pfn(x))
 192
 193 #define PMD_BAD_BITS            (PTE_TABLE_SIZE-1)
 194 #define PUD_BAD_BITS            (PMD_TABLE_SIZE-1)
 195
 196 #define pmd_set(pmdp, pmdval)   (pmd_val(*(pmdp)) = (pmdval))
 197 #define pmd_none(pmd)           (!pmd_val(pmd))
 198 #define pmd_bad(pmd)            (!is_kernel_addr(pmd_val(pmd)) \
 199                                  || (pmd_val(pmd) & PMD_BAD_BITS))
 200 #define pmd_present(pmd)        (pmd_val(pmd) != 0)
 201 #define pmd_clear(pmdp)         (pmd_val(*(pmdp)) = 0)
 202 #define pmd_page_vaddr(pmd)     (pmd_val(pmd) & ~PMD_MASKED_BITS)
 203 #define pmd_page(pmd)           virt_to_page(pmd_page_vaddr(pmd))
 204
 205 #define pud_set(pudp, pudval)   (pud_val(*(pudp)) = (pudval))
 206 #define pud_none(pud)           (!pud_val(pud))
 207 #define pud_bad(pud)            (!is_kernel_addr(pud_val(pud)) \
 208                                  || (pud_val(pud) & PUD_BAD_BITS))
 209 #define pud_present(pud)        (pud_val(pud) != 0)
 210 #define pud_clear(pudp)         (pud_val(*(pudp)) = 0)
 211 #define pud_page_vaddr(pud)     (pud_val(pud) & ~PUD_MASKED_BITS)
 212 #define pud_page(pud)           virt_to_page(pud_page_vaddr(pud))
 213
 214 #define pgd_set(pgdp, pudp)     ({pgd_val(*(pgdp)) = (unsigned long)(pudp);})
 215
 216 /*
 217  * Find an entry in a page-table-directory.  We combine the address region
 218  * (the high order N bits) and the pgd portion of the address.
 219  */
 220 /* to avoid overflow in free_pgtables we don't use PTRS_PER_PGD here */
 221 #define pgd_index(address) (((address) >> (PGDIR_SHIFT)) & 0x1ff)
 222
 223 #define pgd_offset(mm, address)  ((mm)->pgd + pgd_index(address))
 224
 225 #define pmd_offset(pudp,addr) \
 226   (((pmd_t *) pud_page_vaddr(*(pudp))) + (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1)))
 227
 228 #define pte_offset_kernel(dir,addr) \
 229   (((pte_t *) pmd_page_vaddr(*(dir))) + (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
 230
 231 #define pte_offset_map(dir,addr)        pte_offset_kernel((dir), (addr))
 232 #define pte_offset_map_nested(dir,addr) pte_offset_kernel((dir), (addr))
 233 #define pte_unmap(pte)                  do { } while(0)
 234 #define pte_unmap_nested(pte)           do { } while(0)
 235
 236 /* to find an entry in a kernel page-table-directory */
 237 /* This now only contains the vmalloc pages */
 238 #define pgd_offset_k(address) pgd_offset(&init_mm, address)
 239
 240 /*
 241  * The following only work if pte_present() is true.
 242  * Undefined behaviour if not..
 243  */
 244 static inline int pte_read(pte_t pte)  { return pte_val(pte) & _PAGE_USER;}
 245 static inline int pte_write(pte_t pte) { return pte_val(pte) & _PAGE_RW;}
 246 static inline int pte_exec(pte_t pte)  { return pte_val(pte) & _PAGE_EXEC;}
 247 static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY;}
 248 static inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED;}
 249 static inline int pte_file(pte_t pte) { return pte_val(pte) & _PAGE_FILE;}
 250
 251 static inline void pte_uncache(pte_t pte) { pte_val(pte) |= _PAGE_NO_CACHE; }
 252 static inline void pte_cache(pte_t pte)   { pte_val(pte) &= ~_PAGE_NO_CACHE; }
 253
 254 static inline pte_t pte_rdprotect(pte_t pte) {
 255         pte_val(pte) &= ~_PAGE_USER; return pte; }
 256 static inline pte_t pte_exprotect(pte_t pte) {
 257         pte_val(pte) &= ~_PAGE_EXEC; return pte; }
 258 static inline pte_t pte_wrprotect(pte_t pte) {
 259         pte_val(pte) &= ~(_PAGE_RW); return pte; }
 260 static inline pte_t pte_mkclean(pte_t pte) {
 261         pte_val(pte) &= ~(_PAGE_DIRTY); return pte; }
 262 static inline pte_t pte_mkold(pte_t pte) {
 263         pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
 264 static inline pte_t pte_mkread(pte_t pte) {
 265         pte_val(pte) |= _PAGE_USER; return pte; }
 266 static inline pte_t pte_mkexec(pte_t pte) {
 267         pte_val(pte) |= _PAGE_USER | _PAGE_EXEC; return pte; }
 268 static inline pte_t pte_mkwrite(pte_t pte) {
 269         pte_val(pte) |= _PAGE_RW; return pte; }
 270 static inline pte_t pte_mkdirty(pte_t pte) {
 271         pte_val(pte) |= _PAGE_DIRTY; return pte; }
 272 static inline pte_t pte_mkyoung(pte_t pte) {
 273         pte_val(pte) |= _PAGE_ACCESSED; return pte; }
 274 static inline pte_t pte_mkhuge(pte_t pte) {
 275         return pte; }
 276
 277 /* Atomic PTE updates */
 278 static inline unsigned long pte_update(struct mm_struct *mm,
 279                                        unsigned long addr,
 280                                        pte_t *ptep, unsigned long clr,
 281                                        int huge)
 282 {
 283         unsigned long old, tmp;
 284
 285         __asm__ __volatile__(
 286         "1:     ldarx   %0,0,%3         # pte_update\n\
 287         andi.   %1,%0,%6\n\
 288         bne-    1b \n\
 289         andc    %1,%0,%4 \n\
 290         stdcx.  %1,0,%3 \n\
 291         bne-    1b"
 292         : "=&r" (old), "=&r" (tmp), "=m" (*ptep)
 293         : "r" (ptep), "r" (clr), "m" (*ptep), "i" (_PAGE_BUSY)
 294         : "cc" );
 295
 296         if (old & _PAGE_HASHPTE)
 297                 hpte_need_flush(mm, addr, ptep, old, huge);
 298         return old;
 299 }
 300
 301 static inline int __ptep_test_and_clear_young(struct mm_struct *mm,
 302                                               unsigned long addr, pte_t *ptep)
 303 {
 304         unsigned long old;
 305
 306         if ((pte_val(*ptep) & (_PAGE_ACCESSED | _PAGE_HASHPTE)) == 0)
 307                 return 0;
 308         old = pte_update(mm, addr, ptep, _PAGE_ACCESSED, 0);
 309         return (old & _PAGE_ACCESSED) != 0;
 310 }
 311 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
 312 #define ptep_test_and_clear_young(__vma, __addr, __ptep)                   \
 313 ({                                                                         \
 314         int __r;                                                           \
 315         __r = __ptep_test_and_clear_young((__vma)->vm_mm, __addr, __ptep); \
 316         __r;                                                               \
 317 })
 318
 319 /*
 320  * On RW/DIRTY bit transitions we can avoid flushing the hpte. For the
 321  * moment we always flush but we need to fix hpte_update and test if the
 322  * optimisation is worth it.
 323  */
 324 static inline int __ptep_test_and_clear_dirty(struct mm_struct *mm,
 325                                               unsigned long addr, pte_t *ptep)
 326 {
 327         unsigned long old;
 328
 329         if ((pte_val(*ptep) & _PAGE_DIRTY) == 0)
 330                 return 0;
 331         old = pte_update(mm, addr, ptep, _PAGE_DIRTY, 0);
 332         return (old & _PAGE_DIRTY) != 0;
 333 }
 334 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
 335 #define ptep_test_and_clear_dirty(__vma, __addr, __ptep)                   \
 336 ({                                                                         \
 337         int __r;                                                           \
 338         __r = __ptep_test_and_clear_dirty((__vma)->vm_mm, __addr, __ptep); \
 339         __r;                                                               \
 340 })
 341
 342 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
 343 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
 344                                       pte_t *ptep)
 345 {
 346         unsigned long old;
 347
 348         if ((pte_val(*ptep) & _PAGE_RW) == 0)
 349                 return;
 350         old = pte_update(mm, addr, ptep, _PAGE_RW, 0);
 351 }
 352
 353 /*
 354  * We currently remove entries from the hashtable regardless of whether
 355  * the entry was young or dirty. The generic routines only flush if the
 356  * entry was young or dirty which is not good enough.
 357  *
 358  * We should be more intelligent about this but for the moment we override
 359  * these functions and force a tlb flush unconditionally
 360  */
 361 #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
 362 #define ptep_clear_flush_young(__vma, __address, __ptep)                \
 363 ({                                                                      \
 364         int __young = __ptep_test_and_clear_young((__vma)->vm_mm, __address, \
 365                                                   __ptep);              \
 366         __young;                                                        \
 367 })
 368
 369 #define __HAVE_ARCH_PTEP_CLEAR_DIRTY_FLUSH
 370 #define ptep_clear_flush_dirty(__vma, __address, __ptep)                \
 371 ({                                                                      \
 372         int __dirty = __ptep_test_and_clear_dirty((__vma)->vm_mm, __address, \
 373                                                   __ptep);              \
 374         __dirty;                                                        \
 375 })
 376
 377 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
 378 static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 379                                        unsigned long addr, pte_t *ptep)
 380 {
 381         unsigned long old = pte_update(mm, addr, ptep, ~0UL, 0);
 382         return __pte(old);
 383 }
 384
 385 static inline void pte_clear(struct mm_struct *mm, unsigned long addr,
 386                              pte_t * ptep)
 387 {
 388         pte_update(mm, addr, ptep, ~0UL, 0);
 389 }
 390
 391 /*
 392  * set_pte stores a linux PTE into the linux page table.
 393  */
 394 static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 395                               pte_t *ptep, pte_t pte)
 396 {
 397         if (pte_present(*ptep))
 398                 pte_clear(mm, addr, ptep);
 399         pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
 400         *ptep = pte;
 401 }
 402
 403 /* Set the dirty and/or accessed bits atomically in a linux PTE, this
 404  * function doesn't need to flush the hash entry
 405  */
 406 #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
 407 static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry, int dirty)
 408 {
 409         unsigned long bits = pte_val(entry) &
 410                 (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
 411         unsigned long old, tmp;
 412
 413         __asm__ __volatile__(
 414         "1:     ldarx   %0,0,%4\n\
 415                 andi.   %1,%0,%6\n\
 416                 bne-    1b \n\
 417                 or      %0,%3,%0\n\
 418                 stdcx.  %0,0,%4\n\
 419                 bne-    1b"
 420         :"=&r" (old), "=&r" (tmp), "=m" (*ptep)
 421         :"r" (bits), "r" (ptep), "m" (*ptep), "i" (_PAGE_BUSY)
 422         :"cc");
 423 }
 424 #define  ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
 425         do {                                                               \
 426                 __ptep_set_access_flags(__ptep, __entry, __dirty);         \
 427                 flush_tlb_page_nohash(__vma, __address);                   \
 428         } while(0)
 429
 430 /*
 431  * Macro to mark a page protection value as "uncacheable".
 432  */
 433 #define pgprot_noncached(prot)  (__pgprot(pgprot_val(prot) | _PAGE_NO_CACHE | _PAGE_GUARDED))
 434
 435 struct file;
 436 extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 437                                      unsigned long size, pgprot_t vma_prot);
 438 #define __HAVE_PHYS_MEM_ACCESS_PROT
 439
 440 #define __HAVE_ARCH_PTE_SAME
 441 #define pte_same(A,B)   (((pte_val(A) ^ pte_val(B)) & ~_PAGE_HPTEFLAGS) == 0)
 442
 443 #define pte_ERROR(e) \
 444         printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
 445 #define pmd_ERROR(e) \
 446         printk("%s:%d: bad pmd %08lx.\n", __FILE__, __LINE__, pmd_val(e))
 447 #define pgd_ERROR(e) \
 448         printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
 449
 450 extern pgd_t swapper_pg_dir[];
 451
 452 extern void paging_init(void);
 453
 454 /* Encode and de-code a swap entry */
 455 #define __swp_type(entry)       (((entry).val >> 1) & 0x3f)
 456 #define __swp_offset(entry)     ((entry).val >> 8)
 457 #define __swp_entry(type, offset) ((swp_entry_t){((type)<< 1)|((offset)<<8)})
 458 #define __pte_to_swp_entry(pte) ((swp_entry_t){pte_val(pte) >> PTE_RPN_SHIFT})
 459 #define __swp_entry_to_pte(x)   ((pte_t) { (x).val << PTE_RPN_SHIFT })
 460 #define pte_to_pgoff(pte)       (pte_val(pte) >> PTE_RPN_SHIFT)
 461 #define pgoff_to_pte(off)       ((pte_t) {((off) << PTE_RPN_SHIFT)|_PAGE_FILE})
 462 #define PTE_FILE_MAX_BITS       (BITS_PER_LONG - PTE_RPN_SHIFT)
 463
 464 /*
 465  * kern_addr_valid is intended to indicate whether an address is a valid
 466  * kernel address.  Most 32-bit archs define it as always true (like this)
 467  * but most 64-bit archs actually perform a test.  What should we do here?
 468  * The only use is in fs/ncpfs/dir.c
 469  */
 470 #define kern_addr_valid(addr)   (1)
 471
 472 #define io_remap_pfn_range(vma, vaddr, pfn, size, prot)         \
 473                 remap_pfn_range(vma, vaddr, pfn, size, prot)
 474
 475 void pgtable_cache_init(void);
 476
 477 /*
 478  * find_linux_pte returns the address of a linux pte for a given
 479  * effective address and directory.  If not found, it returns zero.
 480  */static inline pte_t *find_linux_pte(pgd_t *pgdir, unsigned long ea)
 481 {
 482         pgd_t *pg;
 483         pud_t *pu;
 484         pmd_t *pm;
 485         pte_t *pt = NULL;
 486
 487         pg = pgdir + pgd_index(ea);
 488         if (!pgd_none(*pg)) {
 489                 pu = pud_offset(pg, ea);
 490                 if (!pud_none(*pu)) {
 491                         pm = pmd_offset(pu, ea);
 492                         if (pmd_present(*pm))
 493                                 pt = pte_offset_kernel(pm, ea);
 494                 }
 495         }
 496         return pt;
 497 }
 498
 499 #endif /* __ASSEMBLY__ */
 500
 501 #endif /* _ASM_POWERPC_PGTABLE_PPC64_H_ */