include/asm-arm/pgtable.h

   1 /*
   2  *  linux/include/asm-arm/pgtable.h
   3  *
   4  *  Copyright (C) 1995-2002 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #ifndef _ASMARM_PGTABLE_H
  11 #define _ASMARM_PGTABLE_H
  12
  13 #include <asm-generic/4level-fixup.h>
  14 #include <asm/proc-fns.h>
  15
  16 #ifndef CONFIG_MMU
  17
  18 #include "pgtable-nommu.h"
  19
  20 #else
  21
  22 #include <asm/memory.h>
  23 #include <asm/arch/vmalloc.h>
  24 #include <asm/pgtable-hwdef.h>
  25
  26 /*
  27  * Just any arbitrary offset to the start of the vmalloc VM area: the
  28  * current 8MB value just means that there will be a 8MB "hole" after the
  29  * physical memory until the kernel virtual memory starts.  That means that
  30  * any out-of-bounds memory accesses will hopefully be caught.
  31  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
  32  * area for the same reason. ;)
  33  *
  34  * Note that platforms may override VMALLOC_START, but they must provide
  35  * VMALLOC_END.  VMALLOC_END defines the (exclusive) limit of this space,
  36  * which may not overlap IO space.
  37  */
  38 #ifndef VMALLOC_START
  39 #define VMALLOC_OFFSET          (8*1024*1024)
  40 #define VMALLOC_START           (((unsigned long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
  41 #endif
  42
  43 /*
  44  * Hardware-wise, we have a two level page table structure, where the first
  45  * level has 4096 entries, and the second level has 256 entries.  Each entry
  46  * is one 32-bit word.  Most of the bits in the second level entry are used
  47  * by hardware, and there aren't any "accessed" and "dirty" bits.
  48  *
  49  * Linux on the other hand has a three level page table structure, which can
  50  * be wrapped to fit a two level page table structure easily - using the PGD
  51  * and PTE only.  However, Linux also expects one "PTE" table per page, and
  52  * at least a "dirty" bit.
  53  *
  54  * Therefore, we tweak the implementation slightly - we tell Linux that we
  55  * have 2048 entries in the first level, each of which is 8 bytes (iow, two
  56  * hardware pointers to the second level.)  The second level contains two
  57  * hardware PTE tables arranged contiguously, followed by Linux versions
  58  * which contain the state information Linux needs.  We, therefore, end up
  59  * with 512 entries in the "PTE" level.
  60  *
  61  * This leads to the page tables having the following layout:
  62  *
  63  *    pgd             pte
  64  * |        |
  65  * +--------+ +0
  66  * |        |-----> +------------+ +0
  67  * +- - - - + +4    |  h/w pt 0  |
  68  * |        |-----> +------------+ +1024
  69  * +--------+ +8    |  h/w pt 1  |
  70  * |        |       +------------+ +2048
  71  * +- - - - +       | Linux pt 0 |
  72  * |        |       +------------+ +3072
  73  * +--------+       | Linux pt 1 |
  74  * |        |       +------------+ +4096
  75  *
  76  * See L_PTE_xxx below for definitions of bits in the "Linux pt", and
  77  * PTE_xxx for definitions of bits appearing in the "h/w pt".
  78  *
  79  * PMD_xxx definitions refer to bits in the first level page table.
  80  *
  81  * The "dirty" bit is emulated by only granting hardware write permission
  82  * iff the page is marked "writable" and "dirty" in the Linux PTE.  This
  83  * means that a write to a clean page will cause a permission fault, and
  84  * the Linux MM layer will mark the page dirty via handle_pte_fault().
  85  * For the hardware to notice the permission change, the TLB entry must
  86  * be flushed, and ptep_set_access_flags() does that for us.
  87  *
  88  * The "accessed" or "young" bit is emulated by a similar method; we only
  89  * allow accesses to the page if the "young" bit is set.  Accesses to the
  90  * page will cause a fault, and handle_pte_fault() will set the young bit
  91  * for us as long as the page is marked present in the corresponding Linux
  92  * PTE entry.  Again, ptep_set_access_flags() will ensure that the TLB is
  93  * up to date.
  94  *
  95  * However, when the "young" bit is cleared, we deny access to the page
  96  * by clearing the hardware PTE.  Currently Linux does not flush the TLB
  97  * for us in this case, which means the TLB will retain the transation
  98  * until either the TLB entry is evicted under pressure, or a context
  99  * switch which changes the user space mapping occurs.
 100  */
 101 #define PTRS_PER_PTE            512
 102 #define PTRS_PER_PMD            1
 103 #define PTRS_PER_PGD            2048
 104
 105 /*
 106  * PMD_SHIFT determines the size of the area a second-level page table can map
 107  * PGDIR_SHIFT determines what a third-level page table entry can map
 108  */
 109 #define PMD_SHIFT               21
 110 #define PGDIR_SHIFT             21
 111
 112 #define LIBRARY_TEXT_START      0x0c000000
 113
 114 #ifndef __ASSEMBLY__
 115 extern void __pte_error(const char *file, int line, unsigned long val);
 116 extern void __pmd_error(const char *file, int line, unsigned long val);
 117 extern void __pgd_error(const char *file, int line, unsigned long val);
 118
 119 #define pte_ERROR(pte)          __pte_error(__FILE__, __LINE__, pte_val(pte))
 120 #define pmd_ERROR(pmd)          __pmd_error(__FILE__, __LINE__, pmd_val(pmd))
 121 #define pgd_ERROR(pgd)          __pgd_error(__FILE__, __LINE__, pgd_val(pgd))
 122 #endif /* !__ASSEMBLY__ */
 123
 124 #define PMD_SIZE                (1UL << PMD_SHIFT)
 125 #define PMD_MASK                (~(PMD_SIZE-1))
 126 #define PGDIR_SIZE              (1UL << PGDIR_SHIFT)
 127 #define PGDIR_MASK              (~(PGDIR_SIZE-1))
 128
 129 /*
 130  * This is the lowest virtual address we can permit any user space
 131  * mapping to be mapped at.  This is particularly important for
 132  * non-high vector CPUs.
 133  */
 134 #define FIRST_USER_ADDRESS      PAGE_SIZE
 135
 136 #define FIRST_USER_PGD_NR       1
 137 #define USER_PTRS_PER_PGD       ((TASK_SIZE/PGDIR_SIZE) - FIRST_USER_PGD_NR)
 138
 139 /*
 140  * section address mask and size definitions.
 141  */
 142 #define SECTION_SHIFT           20
 143 #define SECTION_SIZE            (1UL << SECTION_SHIFT)
 144 #define SECTION_MASK            (~(SECTION_SIZE-1))
 145
 146 /*
 147  * ARMv6 supersection address mask and size definitions.
 148  */
 149 #define SUPERSECTION_SHIFT      24
 150 #define SUPERSECTION_SIZE       (1UL << SUPERSECTION_SHIFT)
 151 #define SUPERSECTION_MASK       (~(SUPERSECTION_SIZE-1))
 152
 153 /*
 154  * "Linux" PTE definitions.
 155  *
 156  * We keep two sets of PTEs - the hardware and the linux version.
 157  * This allows greater flexibility in the way we map the Linux bits
 158  * onto the hardware tables, and allows us to have YOUNG and DIRTY
 159  * bits.
 160  *
 161  * The PTE table pointer refers to the hardware entries; the "Linux"
 162  * entries are stored 1024 bytes below.
 163  */
 164 #define L_PTE_PRESENT           (1 << 0)
 165 #define L_PTE_FILE              (1 << 1)        /* only when !PRESENT */
 166 #define L_PTE_YOUNG             (1 << 1)
 167 #define L_PTE_BUFFERABLE        (1 << 2)        /* matches PTE */
 168 #define L_PTE_CACHEABLE         (1 << 3)        /* matches PTE */
 169 #define L_PTE_USER              (1 << 4)
 170 #define L_PTE_WRITE             (1 << 5)
 171 #define L_PTE_EXEC              (1 << 6)
 172 #define L_PTE_DIRTY             (1 << 7)
 173 #define L_PTE_SHARED            (1 << 10)       /* shared(v6), coherent(xsc3) */
 174
 175 #ifndef __ASSEMBLY__
 176
 177 /*
 178  * The pgprot_* and protection_map entries will be fixed up in runtime
 179  * to include the cachable and bufferable bits based on memory policy,
 180  * as well as any architecture dependent bits like global/ASID and SMP
 181  * shared mapping bits.
 182  */
 183 #define _L_PTE_DEFAULT  L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_CACHEABLE | L_PTE_BUFFERABLE
 184 #define _L_PTE_READ     L_PTE_USER | L_PTE_EXEC
 185
 186 extern pgprot_t         pgprot_user;
 187 extern pgprot_t         pgprot_kernel;
 188
 189 #define PAGE_NONE       pgprot_user
 190 #define PAGE_COPY       __pgprot(pgprot_val(pgprot_user) | _L_PTE_READ)
 191 #define PAGE_SHARED     __pgprot(pgprot_val(pgprot_user) | _L_PTE_READ | \
 192                                  L_PTE_WRITE)
 193 #define PAGE_READONLY   __pgprot(pgprot_val(pgprot_user) | _L_PTE_READ)
 194 #define PAGE_KERNEL     pgprot_kernel
 195
 196 #define __PAGE_NONE     __pgprot(_L_PTE_DEFAULT)
 197 #define __PAGE_COPY     __pgprot(_L_PTE_DEFAULT | _L_PTE_READ)
 198 #define __PAGE_SHARED   __pgprot(_L_PTE_DEFAULT | _L_PTE_READ | L_PTE_WRITE)
 199 #define __PAGE_READONLY __pgprot(_L_PTE_DEFAULT | _L_PTE_READ)
 200
 201 #endif /* __ASSEMBLY__ */
 202
 203 /*
 204  * The table below defines the page protection levels that we insert into our
 205  * Linux page table version.  These get translated into the best that the
 206  * architecture can perform.  Note that on most ARM hardware:
 207  *  1) We cannot do execute protection
 208  *  2) If we could do execute protection, then read is implied
 209  *  3) write implies read permissions
 210  */
 211 #define __P000  __PAGE_NONE
 212 #define __P001  __PAGE_READONLY
 213 #define __P010  __PAGE_COPY
 214 #define __P011  __PAGE_COPY
 215 #define __P100  __PAGE_READONLY
 216 #define __P101  __PAGE_READONLY
 217 #define __P110  __PAGE_COPY
 218 #define __P111  __PAGE_COPY
 219
 220 #define __S000  __PAGE_NONE
 221 #define __S001  __PAGE_READONLY
 222 #define __S010  __PAGE_SHARED
 223 #define __S011  __PAGE_SHARED
 224 #define __S100  __PAGE_READONLY
 225 #define __S101  __PAGE_READONLY
 226 #define __S110  __PAGE_SHARED
 227 #define __S111  __PAGE_SHARED
 228
 229 #ifndef __ASSEMBLY__
 230 /*
 231  * ZERO_PAGE is a global shared page that is always zero: used
 232  * for zero-mapped memory areas etc..
 233  */
 234 extern struct page *empty_zero_page;
 235 #define ZERO_PAGE(vaddr)        (empty_zero_page)
 236
 237 #define pte_pfn(pte)            (pte_val(pte) >> PAGE_SHIFT)
 238 #define pfn_pte(pfn,prot)       (__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot)))
 239
 240 #define pte_none(pte)           (!pte_val(pte))
 241 #define pte_clear(mm,addr,ptep) set_pte_ext(ptep, __pte(0), 0)
 242 #define pte_page(pte)           (pfn_to_page(pte_pfn(pte)))
 243 #define pte_offset_kernel(dir,addr)     (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 244 #define pte_offset_map(dir,addr)        (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 245 #define pte_offset_map_nested(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 246 #define pte_unmap(pte)          do { } while (0)
 247 #define pte_unmap_nested(pte)   do { } while (0)
 248
 249 #define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext)
 250
 251 #define set_pte_at(mm,addr,ptep,pteval) do { \
 252         set_pte_ext(ptep, pteval, (addr) >= TASK_SIZE ? 0 : PTE_EXT_NG); \
 253  } while (0)
 254
 255 /*
 256  * The following only work if pte_present() is true.
 257  * Undefined behaviour if not..
 258  */
 259 #define pte_present(pte)        (pte_val(pte) & L_PTE_PRESENT)
 260 #define pte_write(pte)          (pte_val(pte) & L_PTE_WRITE)
 261 #define pte_dirty(pte)          (pte_val(pte) & L_PTE_DIRTY)
 262 #define pte_young(pte)          (pte_val(pte) & L_PTE_YOUNG)
 263
 264 /*
 265  * The following only works if pte_present() is not true.
 266  */
 267 #define pte_file(pte)           (pte_val(pte) & L_PTE_FILE)
 268 #define pte_to_pgoff(x)         (pte_val(x) >> 2)
 269 #define pgoff_to_pte(x)         __pte(((x) << 2) | L_PTE_FILE)
 270
 271 #define PTE_FILE_MAX_BITS       30
 272
 273 #define PTE_BIT_FUNC(fn,op) \
 274 static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
 275
 276 PTE_BIT_FUNC(wrprotect, &= ~L_PTE_WRITE);
 277 PTE_BIT_FUNC(mkwrite,   |= L_PTE_WRITE);
 278 PTE_BIT_FUNC(mkclean,   &= ~L_PTE_DIRTY);
 279 PTE_BIT_FUNC(mkdirty,   |= L_PTE_DIRTY);
 280 PTE_BIT_FUNC(mkold,     &= ~L_PTE_YOUNG);
 281 PTE_BIT_FUNC(mkyoung,   |= L_PTE_YOUNG);
 282
 283 /*
 284  * Mark the prot value as uncacheable and unbufferable.
 285  */
 286 #define pgprot_noncached(prot)  __pgprot(pgprot_val(prot) & ~(L_PTE_CACHEABLE | L_PTE_BUFFERABLE))
 287 #define pgprot_writecombine(prot) __pgprot(pgprot_val(prot) & ~L_PTE_CACHEABLE)
 288
 289 #define pmd_none(pmd)           (!pmd_val(pmd))
 290 #define pmd_present(pmd)        (pmd_val(pmd))
 291 #define pmd_bad(pmd)            (pmd_val(pmd) & 2)
 292
 293 #define copy_pmd(pmdpd,pmdps)           \
 294         do {                            \
 295                 pmdpd[0] = pmdps[0];    \
 296                 pmdpd[1] = pmdps[1];    \
 297                 flush_pmd_entry(pmdpd); \
 298         } while (0)
 299
 300 #define pmd_clear(pmdp)                 \
 301         do {                            \
 302                 pmdp[0] = __pmd(0);     \
 303                 pmdp[1] = __pmd(0);     \
 304                 clean_pmd_entry(pmdp);  \
 305         } while (0)
 306
 307 static inline pte_t *pmd_page_vaddr(pmd_t pmd)
 308 {
 309         unsigned long ptr;
 310
 311         ptr = pmd_val(pmd) & ~(PTRS_PER_PTE * sizeof(void *) - 1);
 312         ptr += PTRS_PER_PTE * sizeof(void *);
 313
 314         return __va(ptr);
 315 }
 316
 317 #define pmd_page(pmd) virt_to_page(__va(pmd_val(pmd)))
 318
 319 /*
 320  * Permanent address of a page. We never have highmem, so this is trivial.
 321  */
 322 #define pages_to_mb(x)          ((x) >> (20 - PAGE_SHIFT))
 323
 324 /*
 325  * Conversion functions: convert a page and protection to a page entry,
 326  * and a page entry and page directory to the page they refer to.
 327  */
 328 #define mk_pte(page,prot)       pfn_pte(page_to_pfn(page),prot)
 329
 330 /*
 331  * The "pgd_xxx()" functions here are trivial for a folded two-level
 332  * setup: the pgd is never bad, and a pmd always exists (as it's folded
 333  * into the pgd entry)
 334  */
 335 #define pgd_none(pgd)           (0)
 336 #define pgd_bad(pgd)            (0)
 337 #define pgd_present(pgd)        (1)
 338 #define pgd_clear(pgdp)         do { } while (0)
 339 #define set_pgd(pgd,pgdp)       do { } while (0)
 340
 341 /* to find an entry in a page-table-directory */
 342 #define pgd_index(addr)         ((addr) >> PGDIR_SHIFT)
 343
 344 #define pgd_offset(mm, addr)    ((mm)->pgd+pgd_index(addr))
 345
 346 /* to find an entry in a kernel page-table-directory */
 347 #define pgd_offset_k(addr)      pgd_offset(&init_mm, addr)
 348
 349 /* Find an entry in the second-level page table.. */
 350 #define pmd_offset(dir, addr)   ((pmd_t *)(dir))
 351
 352 /* Find an entry in the third-level page table.. */
 353 #define __pte_index(addr)       (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 354
 355 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 356 {
 357         const unsigned long mask = L_PTE_EXEC | L_PTE_WRITE | L_PTE_USER;
 358         pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
 359         return pte;
 360 }
 361
 362 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
 363
 364 /* Encode and decode a swap entry.
 365  *
 366  * We support up to 32GB of swap on 4k machines
 367  */
 368 #define __swp_type(x)           (((x).val >> 2) & 0x7f)
 369 #define __swp_offset(x)         ((x).val >> 9)
 370 #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 2) | ((offset) << 9) })
 371 #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
 372 #define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })
 373
 374 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
 375 /* FIXME: this is not correct */
 376 #define kern_addr_valid(addr)   (1)
 377
 378 #include <asm-generic/pgtable.h>
 379
 380 /*
 381  * We provide our own arch_get_unmapped_area to cope with VIPT caches.
 382  */
 383 #define HAVE_ARCH_UNMAPPED_AREA
 384
 385 /*
 386  * remap a physical page `pfn' of size `size' with page protection `prot'
 387  * into virtual address `from'
 388  */
 389 #define io_remap_pfn_range(vma,from,pfn,size,prot) \
 390                 remap_pfn_range(vma, from, pfn, size, prot)
 391
 392 #define pgtable_cache_init() do { } while (0)
 393
 394 #endif /* !__ASSEMBLY__ */
 395
 396 #endif /* CONFIG_MMU */
 397
 398 #endif /* _ASMARM_PGTABLE_H */