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
  15 #include <asm/memory.h>
  16 #include <asm/proc-fns.h>
  17 #include <asm/arch/vmalloc.h>
  18
  19 /*
  20  * Just any arbitrary offset to the start of the vmalloc VM area: the
  21  * current 8MB value just means that there will be a 8MB "hole" after the
  22  * physical memory until the kernel virtual memory starts.  That means that
  23  * any out-of-bounds memory accesses will hopefully be caught.
  24  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
  25  * area for the same reason. ;)
  26  *
  27  * Note that platforms may override VMALLOC_START, but they must provide
  28  * VMALLOC_END.  VMALLOC_END defines the (exclusive) limit of this space,
  29  * which may not overlap IO space.
  30  */
  31 #ifndef VMALLOC_START
  32 #define VMALLOC_OFFSET          (8*1024*1024)
  33 #define VMALLOC_START           (((unsigned long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
  34 #endif
  35
  36 /*
  37  * Hardware-wise, we have a two level page table structure, where the first
  38  * level has 4096 entries, and the second level has 256 entries.  Each entry
  39  * is one 32-bit word.  Most of the bits in the second level entry are used
  40  * by hardware, and there aren't any "accessed" and "dirty" bits.
  41  *
  42  * Linux on the other hand has a three level page table structure, which can
  43  * be wrapped to fit a two level page table structure easily - using the PGD
  44  * and PTE only.  However, Linux also expects one "PTE" table per page, and
  45  * at least a "dirty" bit.
  46  *
  47  * Therefore, we tweak the implementation slightly - we tell Linux that we
  48  * have 2048 entries in the first level, each of which is 8 bytes (iow, two
  49  * hardware pointers to the second level.)  The second level contains two
  50  * hardware PTE tables arranged contiguously, followed by Linux versions
  51  * which contain the state information Linux needs.  We, therefore, end up
  52  * with 512 entries in the "PTE" level.
  53  *
  54  * This leads to the page tables having the following layout:
  55  *
  56  *    pgd             pte
  57  * |        |
  58  * +--------+ +0
  59  * |        |-----> +------------+ +0
  60  * +- - - - + +4    |  h/w pt 0  |
  61  * |        |-----> +------------+ +1024
  62  * +--------+ +8    |  h/w pt 1  |
  63  * |        |       +------------+ +2048
  64  * +- - - - +       | Linux pt 0 |
  65  * |        |       +------------+ +3072
  66  * +--------+       | Linux pt 1 |
  67  * |        |       +------------+ +4096
  68  *
  69  * See L_PTE_xxx below for definitions of bits in the "Linux pt", and
  70  * PTE_xxx for definitions of bits appearing in the "h/w pt".
  71  *
  72  * PMD_xxx definitions refer to bits in the first level page table.
  73  *
  74  * The "dirty" bit is emulated by only granting hardware write permission
  75  * iff the page is marked "writable" and "dirty" in the Linux PTE.  This
  76  * means that a write to a clean page will cause a permission fault, and
  77  * the Linux MM layer will mark the page dirty via handle_pte_fault().
  78  * For the hardware to notice the permission change, the TLB entry must
  79  * be flushed, and ptep_establish() does that for us.
  80  *
  81  * The "accessed" or "young" bit is emulated by a similar method; we only
  82  * allow accesses to the page if the "young" bit is set.  Accesses to the
  83  * page will cause a fault, and handle_pte_fault() will set the young bit
  84  * for us as long as the page is marked present in the corresponding Linux
  85  * PTE entry.  Again, ptep_establish() will ensure that the TLB is up to
  86  * date.
  87  *
  88  * However, when the "young" bit is cleared, we deny access to the page
  89  * by clearing the hardware PTE.  Currently Linux does not flush the TLB
  90  * for us in this case, which means the TLB will retain the transation
  91  * until either the TLB entry is evicted under pressure, or a context
  92  * switch which changes the user space mapping occurs.
  93  */
  94 #define PTRS_PER_PTE            512
  95 #define PTRS_PER_PMD            1
  96 #define PTRS_PER_PGD            2048
  97
  98 /*
  99  * PMD_SHIFT determines the size of the area a second-level page table can map
 100  * PGDIR_SHIFT determines what a third-level page table entry can map
 101  */
 102 #define PMD_SHIFT               21
 103 #define PGDIR_SHIFT             21
 104
 105 #define LIBRARY_TEXT_START      0x0c000000
 106
 107 #ifndef __ASSEMBLY__
 108 extern void __pte_error(const char *file, int line, unsigned long val);
 109 extern void __pmd_error(const char *file, int line, unsigned long val);
 110 extern void __pgd_error(const char *file, int line, unsigned long val);
 111
 112 #define pte_ERROR(pte)          __pte_error(__FILE__, __LINE__, pte_val(pte))
 113 #define pmd_ERROR(pmd)          __pmd_error(__FILE__, __LINE__, pmd_val(pmd))
 114 #define pgd_ERROR(pgd)          __pgd_error(__FILE__, __LINE__, pgd_val(pgd))
 115 #endif /* !__ASSEMBLY__ */
 116
 117 #define PMD_SIZE                (1UL << PMD_SHIFT)
 118 #define PMD_MASK                (~(PMD_SIZE-1))
 119 #define PGDIR_SIZE              (1UL << PGDIR_SHIFT)
 120 #define PGDIR_MASK              (~(PGDIR_SIZE-1))
 121
 122 /*
 123  * This is the lowest virtual address we can permit any user space
 124  * mapping to be mapped at.  This is particularly important for
 125  * non-high vector CPUs.
 126  */
 127 #define FIRST_USER_ADDRESS      PAGE_SIZE
 128
 129 #define FIRST_USER_PGD_NR       1
 130 #define USER_PTRS_PER_PGD       ((TASK_SIZE/PGDIR_SIZE) - FIRST_USER_PGD_NR)
 131
 132 /*
 133  * ARMv6 supersection address mask and size definitions.
 134  */
 135 #define SUPERSECTION_SHIFT      24
 136 #define SUPERSECTION_SIZE       (1UL << SUPERSECTION_SHIFT)
 137 #define SUPERSECTION_MASK       (~(SUPERSECTION_SIZE-1))
 138
 139 /*
 140  * Hardware page table definitions.
 141  *
 142  * + Level 1 descriptor (PMD)
 143  *   - common
 144  */
 145 #define PMD_TYPE_MASK           (3 << 0)
 146 #define PMD_TYPE_FAULT          (0 << 0)
 147 #define PMD_TYPE_TABLE          (1 << 0)
 148 #define PMD_TYPE_SECT           (2 << 0)
 149 #define PMD_BIT4                (1 << 4)
 150 #define PMD_DOMAIN(x)           ((x) << 5)
 151 #define PMD_PROTECTION          (1 << 9)        /* v5 */
 152 /*
 153  *   - section
 154  */
 155 #define PMD_SECT_BUFFERABLE     (1 << 2)
 156 #define PMD_SECT_CACHEABLE      (1 << 3)
 157 #define PMD_SECT_AP_WRITE       (1 << 10)
 158 #define PMD_SECT_AP_READ        (1 << 11)
 159 #define PMD_SECT_TEX(x)         ((x) << 12)     /* v5 */
 160 #define PMD_SECT_APX            (1 << 15)       /* v6 */
 161 #define PMD_SECT_S              (1 << 16)       /* v6 */
 162 #define PMD_SECT_nG             (1 << 17)       /* v6 */
 163 #define PMD_SECT_SUPER          (1 << 18)       /* v6 */
 164
 165 #define PMD_SECT_UNCACHED       (0)
 166 #define PMD_SECT_BUFFERED       (PMD_SECT_BUFFERABLE)
 167 #define PMD_SECT_WT             (PMD_SECT_CACHEABLE)
 168 #define PMD_SECT_WB             (PMD_SECT_CACHEABLE | PMD_SECT_BUFFERABLE)
 169 #define PMD_SECT_MINICACHE      (PMD_SECT_TEX(1) | PMD_SECT_CACHEABLE)
 170 #define PMD_SECT_WBWA           (PMD_SECT_TEX(1) | PMD_SECT_CACHEABLE | PMD_SECT_BUFFERABLE)
 171
 172 /*
 173  *   - coarse table (not used)
 174  */
 175
 176 /*
 177  * + Level 2 descriptor (PTE)
 178  *   - common
 179  */
 180 #define PTE_TYPE_MASK           (3 << 0)
 181 #define PTE_TYPE_FAULT          (0 << 0)
 182 #define PTE_TYPE_LARGE          (1 << 0)
 183 #define PTE_TYPE_SMALL          (2 << 0)
 184 #define PTE_TYPE_EXT            (3 << 0)        /* v5 */
 185 #define PTE_BUFFERABLE          (1 << 2)
 186 #define PTE_CACHEABLE           (1 << 3)
 187
 188 /*
 189  *   - extended small page/tiny page
 190  */
 191 #define PTE_EXT_XN              (1 << 0)        /* v6 */
 192 #define PTE_EXT_AP_MASK         (3 << 4)
 193 #define PTE_EXT_AP0             (1 << 4)
 194 #define PTE_EXT_AP1             (2 << 4)
 195 #define PTE_EXT_AP_UNO_SRO      (0 << 4)
 196 #define PTE_EXT_AP_UNO_SRW      (PTE_EXT_AP0)
 197 #define PTE_EXT_AP_URO_SRW      (PTE_EXT_AP1)
 198 #define PTE_EXT_AP_URW_SRW      (PTE_EXT_AP1|PTE_EXT_AP0)
 199 #define PTE_EXT_TEX(x)          ((x) << 6)      /* v5 */
 200 #define PTE_EXT_APX             (1 << 9)        /* v6 */
 201 #define PTE_EXT_SHARED          (1 << 10)       /* v6 */
 202 #define PTE_EXT_NG              (1 << 11)       /* v6 */
 203
 204 /*
 205  *   - small page
 206  */
 207 #define PTE_SMALL_AP_MASK       (0xff << 4)
 208 #define PTE_SMALL_AP_UNO_SRO    (0x00 << 4)
 209 #define PTE_SMALL_AP_UNO_SRW    (0x55 << 4)
 210 #define PTE_SMALL_AP_URO_SRW    (0xaa << 4)
 211 #define PTE_SMALL_AP_URW_SRW    (0xff << 4)
 212
 213 /*
 214  * "Linux" PTE definitions.
 215  *
 216  * We keep two sets of PTEs - the hardware and the linux version.
 217  * This allows greater flexibility in the way we map the Linux bits
 218  * onto the hardware tables, and allows us to have YOUNG and DIRTY
 219  * bits.
 220  *
 221  * The PTE table pointer refers to the hardware entries; the "Linux"
 222  * entries are stored 1024 bytes below.
 223  */
 224 #define L_PTE_PRESENT           (1 << 0)
 225 #define L_PTE_FILE              (1 << 1)        /* only when !PRESENT */
 226 #define L_PTE_YOUNG             (1 << 1)
 227 #define L_PTE_BUFFERABLE        (1 << 2)        /* matches PTE */
 228 #define L_PTE_CACHEABLE         (1 << 3)        /* matches PTE */
 229 #define L_PTE_USER              (1 << 4)
 230 #define L_PTE_WRITE             (1 << 5)
 231 #define L_PTE_EXEC              (1 << 6)
 232 #define L_PTE_DIRTY             (1 << 7)
 233 #define L_PTE_SHARED            (1 << 10)       /* shared between CPUs (v6) */
 234 #define L_PTE_ASID              (1 << 11)       /* non-global (use ASID, v6) */
 235
 236 #ifndef __ASSEMBLY__
 237
 238 #include <asm/domain.h>
 239
 240 #define _PAGE_USER_TABLE        (PMD_TYPE_TABLE | PMD_BIT4 | PMD_DOMAIN(DOMAIN_USER))
 241 #define _PAGE_KERNEL_TABLE      (PMD_TYPE_TABLE | PMD_BIT4 | PMD_DOMAIN(DOMAIN_KERNEL))
 242
 243 /*
 244  * The following macros handle the cache and bufferable bits...
 245  */
 246 #define _L_PTE_DEFAULT  L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_CACHEABLE | L_PTE_BUFFERABLE
 247 #define _L_PTE_READ     L_PTE_USER | L_PTE_EXEC
 248
 249 extern pgprot_t         pgprot_kernel;
 250
 251 #define PAGE_NONE       __pgprot(_L_PTE_DEFAULT)
 252 #define PAGE_COPY       __pgprot(_L_PTE_DEFAULT | _L_PTE_READ)
 253 #define PAGE_SHARED     __pgprot(_L_PTE_DEFAULT | _L_PTE_READ | L_PTE_WRITE)
 254 #define PAGE_READONLY   __pgprot(_L_PTE_DEFAULT | _L_PTE_READ)
 255 #define PAGE_KERNEL     pgprot_kernel
 256
 257 #endif /* __ASSEMBLY__ */
 258
 259 /*
 260  * The table below defines the page protection levels that we insert into our
 261  * Linux page table version.  These get translated into the best that the
 262  * architecture can perform.  Note that on most ARM hardware:
 263  *  1) We cannot do execute protection
 264  *  2) If we could do execute protection, then read is implied
 265  *  3) write implies read permissions
 266  */
 267 #define __P000  PAGE_NONE
 268 #define __P001  PAGE_READONLY
 269 #define __P010  PAGE_COPY
 270 #define __P011  PAGE_COPY
 271 #define __P100  PAGE_READONLY
 272 #define __P101  PAGE_READONLY
 273 #define __P110  PAGE_COPY
 274 #define __P111  PAGE_COPY
 275
 276 #define __S000  PAGE_NONE
 277 #define __S001  PAGE_READONLY
 278 #define __S010  PAGE_SHARED
 279 #define __S011  PAGE_SHARED
 280 #define __S100  PAGE_READONLY
 281 #define __S101  PAGE_READONLY
 282 #define __S110  PAGE_SHARED
 283 #define __S111  PAGE_SHARED
 284
 285 #ifndef __ASSEMBLY__
 286 /*
 287  * ZERO_PAGE is a global shared page that is always zero: used
 288  * for zero-mapped memory areas etc..
 289  */
 290 extern struct page *empty_zero_page;
 291 #define ZERO_PAGE(vaddr)        (empty_zero_page)
 292
 293 #define pte_pfn(pte)            (pte_val(pte) >> PAGE_SHIFT)
 294 #define pfn_pte(pfn,prot)       (__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot)))
 295
 296 #define pte_none(pte)           (!pte_val(pte))
 297 #define pte_clear(mm,addr,ptep) set_pte_at((mm),(addr),(ptep), __pte(0))
 298 #define pte_page(pte)           (pfn_to_page(pte_pfn(pte)))
 299 #define pte_offset_kernel(dir,addr)     (pmd_page_kernel(*(dir)) + __pte_index(addr))
 300 #define pte_offset_map(dir,addr)        (pmd_page_kernel(*(dir)) + __pte_index(addr))
 301 #define pte_offset_map_nested(dir,addr) (pmd_page_kernel(*(dir)) + __pte_index(addr))
 302 #define pte_unmap(pte)          do { } while (0)
 303 #define pte_unmap_nested(pte)   do { } while (0)
 304
 305 #define set_pte(ptep, pte)      cpu_set_pte(ptep,pte)
 306 #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
 307
 308 /*
 309  * The following only work if pte_present() is true.
 310  * Undefined behaviour if not..
 311  */
 312 #define pte_present(pte)        (pte_val(pte) & L_PTE_PRESENT)
 313 #define pte_read(pte)           (pte_val(pte) & L_PTE_USER)
 314 #define pte_write(pte)          (pte_val(pte) & L_PTE_WRITE)
 315 #define pte_exec(pte)           (pte_val(pte) & L_PTE_EXEC)
 316 #define pte_dirty(pte)          (pte_val(pte) & L_PTE_DIRTY)
 317 #define pte_young(pte)          (pte_val(pte) & L_PTE_YOUNG)
 318
 319 /*
 320  * The following only works if pte_present() is not true.
 321  */
 322 #define pte_file(pte)           (pte_val(pte) & L_PTE_FILE)
 323 #define pte_to_pgoff(x)         (pte_val(x) >> 2)
 324 #define pgoff_to_pte(x)         __pte(((x) << 2) | L_PTE_FILE)
 325
 326 #define PTE_FILE_MAX_BITS       30
 327
 328 #define PTE_BIT_FUNC(fn,op) \
 329 static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
 330
 331 /*PTE_BIT_FUNC(rdprotect, &= ~L_PTE_USER);*/
 332 /*PTE_BIT_FUNC(mkread,    |= L_PTE_USER);*/
 333 PTE_BIT_FUNC(wrprotect, &= ~L_PTE_WRITE);
 334 PTE_BIT_FUNC(mkwrite,   |= L_PTE_WRITE);
 335 PTE_BIT_FUNC(exprotect, &= ~L_PTE_EXEC);
 336 PTE_BIT_FUNC(mkexec,    |= L_PTE_EXEC);
 337 PTE_BIT_FUNC(mkclean,   &= ~L_PTE_DIRTY);
 338 PTE_BIT_FUNC(mkdirty,   |= L_PTE_DIRTY);
 339 PTE_BIT_FUNC(mkold,     &= ~L_PTE_YOUNG);
 340 PTE_BIT_FUNC(mkyoung,   |= L_PTE_YOUNG);
 341
 342 /*
 343  * Mark the prot value as uncacheable and unbufferable.
 344  */
 345 #define pgprot_noncached(prot)  __pgprot(pgprot_val(prot) & ~(L_PTE_CACHEABLE | L_PTE_BUFFERABLE))
 346 #define pgprot_writecombine(prot) __pgprot(pgprot_val(prot) & ~L_PTE_CACHEABLE)
 347
 348 #define pmd_none(pmd)           (!pmd_val(pmd))
 349 #define pmd_present(pmd)        (pmd_val(pmd))
 350 #define pmd_bad(pmd)            (pmd_val(pmd) & 2)
 351
 352 #define copy_pmd(pmdpd,pmdps)           \
 353         do {                            \
 354                 pmdpd[0] = pmdps[0];    \
 355                 pmdpd[1] = pmdps[1];    \
 356                 flush_pmd_entry(pmdpd); \
 357         } while (0)
 358
 359 #define pmd_clear(pmdp)                 \
 360         do {                            \
 361                 pmdp[0] = __pmd(0);     \
 362                 pmdp[1] = __pmd(0);     \
 363                 clean_pmd_entry(pmdp);  \
 364         } while (0)
 365
 366 static inline pte_t *pmd_page_kernel(pmd_t pmd)
 367 {
 368         unsigned long ptr;
 369
 370         ptr = pmd_val(pmd) & ~(PTRS_PER_PTE * sizeof(void *) - 1);
 371         ptr += PTRS_PER_PTE * sizeof(void *);
 372
 373         return __va(ptr);
 374 }
 375
 376 #define pmd_page(pmd) virt_to_page(__va(pmd_val(pmd)))
 377
 378 /*
 379  * Permanent address of a page. We never have highmem, so this is trivial.
 380  */
 381 #define pages_to_mb(x)          ((x) >> (20 - PAGE_SHIFT))
 382
 383 /*
 384  * Conversion functions: convert a page and protection to a page entry,
 385  * and a page entry and page directory to the page they refer to.
 386  */
 387 #define mk_pte(page,prot)       pfn_pte(page_to_pfn(page),prot)
 388
 389 /*
 390  * The "pgd_xxx()" functions here are trivial for a folded two-level
 391  * setup: the pgd is never bad, and a pmd always exists (as it's folded
 392  * into the pgd entry)
 393  */
 394 #define pgd_none(pgd)           (0)
 395 #define pgd_bad(pgd)            (0)
 396 #define pgd_present(pgd)        (1)
 397 #define pgd_clear(pgdp)         do { } while (0)
 398 #define set_pgd(pgd,pgdp)       do { } while (0)
 399
 400 #define page_pte_prot(page,prot)        mk_pte(page, prot)
 401 #define page_pte(page)          mk_pte(page, __pgprot(0))
 402
 403 /* to find an entry in a page-table-directory */
 404 #define pgd_index(addr)         ((addr) >> PGDIR_SHIFT)
 405
 406 #define pgd_offset(mm, addr)    ((mm)->pgd+pgd_index(addr))
 407
 408 /* to find an entry in a kernel page-table-directory */
 409 #define pgd_offset_k(addr)      pgd_offset(&init_mm, addr)
 410
 411 /* Find an entry in the second-level page table.. */
 412 #define pmd_offset(dir, addr)   ((pmd_t *)(dir))
 413
 414 /* Find an entry in the third-level page table.. */
 415 #define __pte_index(addr)       (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 416
 417 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 418 {
 419         const unsigned long mask = L_PTE_EXEC | L_PTE_WRITE | L_PTE_USER;
 420         pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
 421         return pte;
 422 }
 423
 424 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
 425
 426 /* Encode and decode a swap entry.
 427  *
 428  * We support up to 32GB of swap on 4k machines
 429  */
 430 #define __swp_type(x)           (((x).val >> 2) & 0x7f)
 431 #define __swp_offset(x)         ((x).val >> 9)
 432 #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 2) | ((offset) << 9) })
 433 #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
 434 #define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })
 435
 436 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
 437 /* FIXME: this is not correct */
 438 #define kern_addr_valid(addr)   (1)
 439
 440 #include <asm-generic/pgtable.h>
 441
 442 /*
 443  * We provide our own arch_get_unmapped_area to cope with VIPT caches.
 444  */
 445 #define HAVE_ARCH_UNMAPPED_AREA
 446
 447 /*
 448  * remap a physical page `pfn' of size `size' with page protection `prot'
 449  * into virtual address `from'
 450  */
 451 #define io_remap_pfn_range(vma,from,pfn,size,prot) \
 452                 remap_pfn_range(vma, from, pfn, size, prot)
 453
 454 #define MK_IOSPACE_PFN(space, pfn)      (pfn)
 455 #define GET_IOSPACE(pfn)                0
 456 #define GET_PFN(pfn)                    (pfn)
 457
 458 #define pgtable_cache_init() do { } while (0)
 459
 460 #endif /* !__ASSEMBLY__ */
 461
 462 #endif /* _ASMARM_PGTABLE_H */