arch/arc/include/asm/pgtable.h

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * vineetg: May 2011
   9  *  -Folded PAGE_PRESENT (used by VM) and PAGE_VALID (used by MMU) into 1.
  10  *     They are semantically the same although in different contexts
  11  *     VALID marks a TLB entry exists and it will only happen if PRESENT
  12  *  - Utilise some unused free bits to confine PTE flags to 12 bits
  13  *     This is a must for 4k pg-sz
  14  *
  15  * vineetg: Mar 2011 - changes to accomodate MMU TLB Page Descriptor mods
  16  *  -TLB Locking never really existed, except for initial specs
  17  *  -SILENT_xxx not needed for our port
  18  *  -Per my request, MMU V3 changes the layout of some of the bits
  19  *     to avoid a few shifts in TLB Miss handlers.
  20  *
  21  * vineetg: April 2010
  22  *  -PGD entry no longer contains any flags. If empty it is 0, otherwise has
  23  *   Pg-Tbl ptr. Thus pmd_present(), pmd_valid(), pmd_set( ) become simpler
  24  *
  25  * vineetg: April 2010
  26  *  -Switched form 8:11:13 split for page table lookup to 11:8:13
  27  *  -this speeds up page table allocation itself as we now have to memset 1K
  28  *    instead of 8k per page table.
  29  * -TODO: Right now page table alloc is 8K and rest 7K is unused
  30  *    need to optimise it
  31  *
  32  * Amit Bhor, Sameer Dhavale: Codito Technologies 2004
  33  */
  34
  35 #ifndef _ASM_ARC_PGTABLE_H
  36 #define _ASM_ARC_PGTABLE_H
  37
  38 #include <asm/page.h>
  39 #include <asm/mmu.h>
  40 #include <asm-generic/pgtable-nopmd.h>
  41
  42 /**************************************************************************
  43  * Page Table Flags
  44  *
  45  * ARC700 MMU only deals with softare managed TLB entries.
  46  * Page Tables are purely for Linux VM's consumption and the bits below are
  47  * suited to that (uniqueness). Hence some are not implemented in the TLB and
  48  * some have different value in TLB.
  49  * e.g. MMU v2: K_READ bit is 8 and so is GLOBAL (possible becoz they live in
  50  *      seperate PD0 and PD1, which combined forms a translation entry)
  51  *      while for PTE perspective, they are 8 and 9 respectively
  52  * with MMU v3: Most bits (except SHARED) represent the exact hardware pos
  53  *      (saves some bit shift ops in TLB Miss hdlrs)
  54  */
  55
  56 #if (CONFIG_ARC_MMU_VER <= 2)
  57
  58 #define _PAGE_ACCESSED      (1<<1)      /* Page is accessed (S) */
  59 #define _PAGE_CACHEABLE     (1<<2)      /* Page is cached (H) */
  60 #define _PAGE_EXECUTE       (1<<3)      /* Page has user execute perm (H) */
  61 #define _PAGE_WRITE         (1<<4)      /* Page has user write perm (H) */
  62 #define _PAGE_READ          (1<<5)      /* Page has user read perm (H) */
  63 #define _PAGE_MODIFIED      (1<<6)      /* Page modified (dirty) (S) */
  64 #define _PAGE_GLOBAL        (1<<8)      /* Page is global (H) */
  65 #define _PAGE_PRESENT       (1<<10)     /* TLB entry is valid (H) */
  66
  67 #else   /* MMU v3 onwards */
  68
  69 #define _PAGE_CACHEABLE     (1<<0)      /* Page is cached (H) */
  70 #define _PAGE_EXECUTE       (1<<1)      /* Page has user execute perm (H) */
  71 #define _PAGE_WRITE         (1<<2)      /* Page has user write perm (H) */
  72 #define _PAGE_READ          (1<<3)      /* Page has user read perm (H) */
  73 #define _PAGE_ACCESSED      (1<<4)      /* Page is accessed (S) */
  74 #define _PAGE_MODIFIED      (1<<5)      /* Page modified (dirty) (S) */
  75
  76 #if (CONFIG_ARC_MMU_VER >= 4)
  77 #define _PAGE_WTHRU         (1<<7)      /* Page cache mode write-thru (H) */
  78 #endif
  79
  80 #define _PAGE_GLOBAL        (1<<8)      /* Page is global (H) */
  81 #define _PAGE_PRESENT       (1<<9)      /* TLB entry is valid (H) */
  82
  83 #if (CONFIG_ARC_MMU_VER >= 4)
  84 #define _PAGE_SZ            (1<<10)     /* Page Size indicator (H) */
  85 #endif
  86
  87 #define _PAGE_SHARED_CODE   (1<<11)     /* Shared Code page with cmn vaddr
  88                                            usable for shared TLB entries (H) */
  89 #endif
  90
  91 /* vmalloc permissions */
  92 #define _K_PAGE_PERMS  (_PAGE_EXECUTE | _PAGE_WRITE | _PAGE_READ | \
  93                         _PAGE_GLOBAL | _PAGE_PRESENT)
  94
  95 #ifdef CONFIG_ARC_CACHE_PAGES
  96 #define _PAGE_DEF_CACHEABLE _PAGE_CACHEABLE
  97 #else
  98 #define _PAGE_DEF_CACHEABLE (0)
  99 #endif
 100
 101 /* Helper for every "user" page
 102  * -kernel can R/W/X
 103  * -by default cached, unless config otherwise
 104  * -present in memory
 105  */
 106 #define ___DEF (_PAGE_PRESENT | _PAGE_DEF_CACHEABLE)
 107
 108 /* Set of bits not changed in pte_modify */
 109 #define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_ACCESSED | _PAGE_MODIFIED)
 110
 111 /* More Abbrevaited helpers */
 112 #define PAGE_U_NONE     __pgprot(___DEF)
 113 #define PAGE_U_R        __pgprot(___DEF | _PAGE_READ)
 114 #define PAGE_U_W_R      __pgprot(___DEF | _PAGE_READ | _PAGE_WRITE)
 115 #define PAGE_U_X_R      __pgprot(___DEF | _PAGE_READ | _PAGE_EXECUTE)
 116 #define PAGE_U_X_W_R    __pgprot(___DEF | _PAGE_READ | _PAGE_WRITE | \
 117                                                        _PAGE_EXECUTE)
 118
 119 #define PAGE_SHARED     PAGE_U_W_R
 120
 121 /* While kernel runs out of unstranslated space, vmalloc/modules use a chunk of
 122  * user vaddr space - visible in all addr spaces, but kernel mode only
 123  * Thus Global, all-kernel-access, no-user-access, cached
 124  */
 125 #define PAGE_KERNEL          __pgprot(_K_PAGE_PERMS | _PAGE_DEF_CACHEABLE)
 126
 127 /* ioremap */
 128 #define PAGE_KERNEL_NO_CACHE __pgprot(_K_PAGE_PERMS)
 129
 130 /* Masks for actual TLB "PD"s */
 131 #define PTE_BITS_IN_PD0         (_PAGE_GLOBAL | _PAGE_PRESENT)
 132 #define PTE_BITS_RWX            (_PAGE_EXECUTE | _PAGE_WRITE | _PAGE_READ)
 133 #define PTE_BITS_NON_RWX_IN_PD1 (PAGE_MASK | _PAGE_CACHEABLE)
 134
 135 /**************************************************************************
 136  * Mapping of vm_flags (Generic VM) to PTE flags (arch specific)
 137  *
 138  * Certain cases have 1:1 mapping
 139  *  e.g. __P101 means VM_READ, VM_EXEC and !VM_SHARED
 140  *       which directly corresponds to  PAGE_U_X_R
 141  *
 142  * Other rules which cause the divergence from 1:1 mapping
 143  *
 144  *  1. Although ARC700 can do exclusive execute/write protection (meaning R
 145  *     can be tracked independet of X/W unlike some other CPUs), still to
 146  *     keep things consistent with other archs:
 147  *      -Write implies Read:   W => R
 148  *      -Execute implies Read: X => R
 149  *
 150  *  2. Pvt Writable doesn't have Write Enabled initially: Pvt-W => !W
 151  *     This is to enable COW mechanism
 152  */
 153         /* xwr */
 154 #define __P000  PAGE_U_NONE
 155 #define __P001  PAGE_U_R
 156 #define __P010  PAGE_U_R        /* Pvt-W => !W */
 157 #define __P011  PAGE_U_R        /* Pvt-W => !W */
 158 #define __P100  PAGE_U_X_R      /* X => R */
 159 #define __P101  PAGE_U_X_R
 160 #define __P110  PAGE_U_X_R      /* Pvt-W => !W and X => R */
 161 #define __P111  PAGE_U_X_R      /* Pvt-W => !W */
 162
 163 #define __S000  PAGE_U_NONE
 164 #define __S001  PAGE_U_R
 165 #define __S010  PAGE_U_W_R      /* W => R */
 166 #define __S011  PAGE_U_W_R
 167 #define __S100  PAGE_U_X_R      /* X => R */
 168 #define __S101  PAGE_U_X_R
 169 #define __S110  PAGE_U_X_W_R    /* X => R */
 170 #define __S111  PAGE_U_X_W_R
 171
 172 /****************************************************************
 173  * Page Table Lookup split
 174  *
 175  * We implement 2 tier paging and since this is all software, we are free
 176  * to customize the span of a PGD / PTE entry to suit us
 177  *
 178  *                      32 bit virtual address
 179  * -------------------------------------------------------
 180  * | BITS_FOR_PGD    |  BITS_FOR_PTE    |  BITS_IN_PAGE  |
 181  * -------------------------------------------------------
 182  *       |                  |                |
 183  *       |                  |                --> off in page frame
 184  *       |                  |
 185  *       |                  ---> index into Page Table
 186  *       |
 187  *       ----> index into Page Directory
 188  */
 189
 190 #define BITS_IN_PAGE    PAGE_SHIFT
 191
 192 /* Optimal Sizing of Pg Tbl - based on MMU page size */
 193 #if defined(CONFIG_ARC_PAGE_SIZE_8K)
 194 #define BITS_FOR_PTE    8
 195 #elif defined(CONFIG_ARC_PAGE_SIZE_16K)
 196 #define BITS_FOR_PTE    8
 197 #elif defined(CONFIG_ARC_PAGE_SIZE_4K)
 198 #define BITS_FOR_PTE    9
 199 #endif
 200
 201 #define BITS_FOR_PGD    (32 - BITS_FOR_PTE - BITS_IN_PAGE)
 202
 203 #define PGDIR_SHIFT     (BITS_FOR_PTE + BITS_IN_PAGE)
 204 #define PGDIR_SIZE      (1UL << PGDIR_SHIFT)    /* vaddr span, not PDG sz */
 205 #define PGDIR_MASK      (~(PGDIR_SIZE-1))
 206
 207 #ifdef __ASSEMBLY__
 208 #define PTRS_PER_PTE    (1 << BITS_FOR_PTE)
 209 #define PTRS_PER_PGD    (1 << BITS_FOR_PGD)
 210 #else
 211 #define PTRS_PER_PTE    (1UL << BITS_FOR_PTE)
 212 #define PTRS_PER_PGD    (1UL << BITS_FOR_PGD)
 213 #endif
 214 /*
 215  * Number of entries a user land program use.
 216  * TASK_SIZE is the maximum vaddr that can be used by a userland program.
 217  */
 218 #define USER_PTRS_PER_PGD       (TASK_SIZE / PGDIR_SIZE)
 219
 220 /*
 221  * No special requirements for lowest virtual address we permit any user space
 222  * mapping to be mapped at.
 223  */
 224 #define FIRST_USER_ADDRESS      0UL
 225
 226
 227 /****************************************************************
 228  * Bucket load of VM Helpers
 229  */
 230
 231 #ifndef __ASSEMBLY__
 232
 233 #define pte_ERROR(e) \
 234         pr_crit("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
 235 #define pgd_ERROR(e) \
 236         pr_crit("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
 237
 238 /* the zero page used for uninitialized and anonymous pages */
 239 extern char empty_zero_page[PAGE_SIZE];
 240 #define ZERO_PAGE(vaddr)        (virt_to_page(empty_zero_page))
 241
 242 #define pte_unmap(pte)          do { } while (0)
 243 #define pte_unmap_nested(pte)           do { } while (0)
 244
 245 #define set_pte(pteptr, pteval) ((*(pteptr)) = (pteval))
 246 #define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)
 247
 248 /* find the page descriptor of the Page Tbl ref by PMD entry */
 249 #define pmd_page(pmd)           virt_to_page(pmd_val(pmd) & PAGE_MASK)
 250
 251 /* find the logical addr (phy for ARC) of the Page Tbl ref by PMD entry */
 252 #define pmd_page_vaddr(pmd)     (pmd_val(pmd) & PAGE_MASK)
 253
 254 /* In a 2 level sys, setup the PGD entry with PTE value */
 255 static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)
 256 {
 257         pmd_val(*pmdp) = (unsigned long)ptep;
 258 }
 259
 260 #define pte_none(x)                     (!pte_val(x))
 261 #define pte_present(x)                  (pte_val(x) & _PAGE_PRESENT)
 262 #define pte_clear(mm, addr, ptep)       set_pte_at(mm, addr, ptep, __pte(0))
 263
 264 #define pmd_none(x)                     (!pmd_val(x))
 265 #define pmd_bad(x)                      ((pmd_val(x) & ~PAGE_MASK))
 266 #define pmd_present(x)                  (pmd_val(x))
 267 #define pmd_clear(xp)                   do { pmd_val(*(xp)) = 0; } while (0)
 268
 269 #define pte_page(x) (mem_map + \
 270                 (unsigned long)(((pte_val(x) - CONFIG_LINUX_LINK_BASE) >> \
 271                                 PAGE_SHIFT)))
 272
 273 #define mk_pte(page, pgprot)                                            \
 274 ({                                                                      \
 275         pte_t pte;                                                      \
 276         pte_val(pte) = __pa(page_address(page)) + pgprot_val(pgprot);   \
 277         pte;                                                            \
 278 })
 279
 280 #define pte_pfn(pte)            (pte_val(pte) >> PAGE_SHIFT)
 281 #define pfn_pte(pfn, prot)      (__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot)))
 282 #define __pte_index(addr)       (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 283
 284 /*
 285  * pte_offset gets a @ptr to PMD entry (PGD in our 2-tier paging system)
 286  * and returns ptr to PTE entry corresponding to @addr
 287  */
 288 #define pte_offset(dir, addr) ((pte_t *)(pmd_page_vaddr(*dir)) +\
 289                                          __pte_index(addr))
 290
 291 /* No mapping of Page Tables in high mem etc, so following same as above */
 292 #define pte_offset_kernel(dir, addr)            pte_offset(dir, addr)
 293 #define pte_offset_map(dir, addr)               pte_offset(dir, addr)
 294
 295 /* Zoo of pte_xxx function */
 296 #define pte_read(pte)           (pte_val(pte) & _PAGE_READ)
 297 #define pte_write(pte)          (pte_val(pte) & _PAGE_WRITE)
 298 #define pte_dirty(pte)          (pte_val(pte) & _PAGE_MODIFIED)
 299 #define pte_young(pte)          (pte_val(pte) & _PAGE_ACCESSED)
 300 #define pte_special(pte)        (0)
 301
 302 #define PTE_BIT_FUNC(fn, op) \
 303         static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
 304
 305 PTE_BIT_FUNC(wrprotect, &= ~(_PAGE_WRITE));
 306 PTE_BIT_FUNC(mkwrite,   |= (_PAGE_WRITE));
 307 PTE_BIT_FUNC(mkclean,   &= ~(_PAGE_MODIFIED));
 308 PTE_BIT_FUNC(mkdirty,   |= (_PAGE_MODIFIED));
 309 PTE_BIT_FUNC(mkold,     &= ~(_PAGE_ACCESSED));
 310 PTE_BIT_FUNC(mkyoung,   |= (_PAGE_ACCESSED));
 311 PTE_BIT_FUNC(exprotect, &= ~(_PAGE_EXECUTE));
 312 PTE_BIT_FUNC(mkexec,    |= (_PAGE_EXECUTE));
 313
 314 static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
 315
 316 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 317 {
 318         return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
 319 }
 320
 321 /* Macro to mark a page protection as uncacheable */
 322 #define pgprot_noncached(prot)  (__pgprot(pgprot_val(prot) & ~_PAGE_CACHEABLE))
 323
 324 static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 325                               pte_t *ptep, pte_t pteval)
 326 {
 327         set_pte(ptep, pteval);
 328 }
 329
 330 /*
 331  * All kernel related VM pages are in init's mm.
 332  */
 333 #define pgd_offset_k(address)   pgd_offset(&init_mm, address)
 334 #define pgd_index(addr)         ((addr) >> PGDIR_SHIFT)
 335 #define pgd_offset(mm, addr)    (((mm)->pgd)+pgd_index(addr))
 336
 337 /*
 338  * Macro to quickly access the PGD entry, utlising the fact that some
 339  * arch may cache the pointer to Page Directory of "current" task
 340  * in a MMU register
 341  *
 342  * Thus task->mm->pgd (3 pointer dereferences, cache misses etc simply
 343  * becomes read a register
 344  *
 345  * ********CAUTION*******:
 346  * Kernel code might be dealing with some mm_struct of NON "current"
 347  * Thus use this macro only when you are certain that "current" is current
 348  * e.g. when dealing with signal frame setup code etc
 349  */
 350 #ifndef CONFIG_SMP
 351 #define pgd_offset_fast(mm, addr)       \
 352 ({                                      \
 353         pgd_t *pgd_base = (pgd_t *) read_aux_reg(ARC_REG_SCRATCH_DATA0);  \
 354         pgd_base + pgd_index(addr);     \
 355 })
 356 #else
 357 #define pgd_offset_fast(mm, addr)       pgd_offset(mm, addr)
 358 #endif
 359
 360 extern void paging_init(void);
 361 extern pgd_t swapper_pg_dir[] __aligned(PAGE_SIZE);
 362 void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 363                       pte_t *ptep);
 364
 365 /* Encode swap {type,off} tuple into PTE
 366  * We reserve 13 bits for 5-bit @type, keeping bits 12-5 zero, ensuring that
 367  * PAGE_PRESENT is zero in a PTE holding swap "identifier"
 368  */
 369 #define __swp_entry(type, off)  ((swp_entry_t) { \
 370                                         ((type) & 0x1f) | ((off) << 13) })
 371
 372 /* Decode a PTE containing swap "identifier "into constituents */
 373 #define __swp_type(pte_lookalike)       (((pte_lookalike).val) & 0x1f)
 374 #define __swp_offset(pte_lookalike)     ((pte_lookalike).val << 13)
 375
 376 /* NOPs, to keep generic kernel happy */
 377 #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
 378 #define __swp_entry_to_pte(x)   ((pte_t) { (x).val })
 379
 380 #define kern_addr_valid(addr)   (1)
 381
 382 /*
 383  * remap a physical page `pfn' of size `size' with page protection `prot'
 384  * into virtual address `from'
 385  */
 386 #include <asm-generic/pgtable.h>
 387
 388 /* to cope with aliasing VIPT cache */
 389 #define HAVE_ARCH_UNMAPPED_AREA
 390
 391 /*
 392  * No page table caches to initialise
 393  */
 394 #define pgtable_cache_init()   do { } while (0)
 395
 396 #endif /* __ASSEMBLY__ */
 397
 398 #endif