linux/arch/alpha/include/asm/pgtable.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ALPHA_PGTABLE_H
   3#define _ALPHA_PGTABLE_H
   4
   5#include <asm-generic/4level-fixup.h>
   6
   7/*
   8 * This file contains the functions and defines necessary to modify and use
   9 * the Alpha page table tree.
  10 *
  11 * This hopefully works with any standard Alpha page-size, as defined
  12 * in <asm/page.h> (currently 8192).
  13 */
  14#include <linux/mmzone.h>
  15
  16#include <asm/page.h>
  17#include <asm/processor.h>      /* For TASK_SIZE */
  18#include <asm/machvec.h>
  19#include <asm/setup.h>
  20
  21struct mm_struct;
  22struct vm_area_struct;
  23
  24/* Certain architectures need to do special things when PTEs
  25 * within a page table are directly modified.  Thus, the following
  26 * hook is made available.
  27 */
  28#define set_pte(pteptr, pteval) ((*(pteptr)) = (pteval))
  29#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
  30
  31/* PMD_SHIFT determines the size of the area a second-level page table can map */
  32#define PMD_SHIFT       (PAGE_SHIFT + (PAGE_SHIFT-3))
  33#define PMD_SIZE        (1UL << PMD_SHIFT)
  34#define PMD_MASK        (~(PMD_SIZE-1))
  35
  36/* PGDIR_SHIFT determines what a third-level page table entry can map */
  37#define PGDIR_SHIFT     (PAGE_SHIFT + 2*(PAGE_SHIFT-3))
  38#define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
  39#define PGDIR_MASK      (~(PGDIR_SIZE-1))
  40
  41/*
  42 * Entries per page directory level:  the Alpha is three-level, with
  43 * all levels having a one-page page table.
  44 */
  45#define PTRS_PER_PTE    (1UL << (PAGE_SHIFT-3))
  46#define PTRS_PER_PMD    (1UL << (PAGE_SHIFT-3))
  47#define PTRS_PER_PGD    (1UL << (PAGE_SHIFT-3))
  48#define USER_PTRS_PER_PGD       (TASK_SIZE / PGDIR_SIZE)
  49#define FIRST_USER_ADDRESS      0UL
  50
  51/* Number of pointers that fit on a page:  this will go away. */
  52#define PTRS_PER_PAGE   (1UL << (PAGE_SHIFT-3))
  53
  54#ifdef CONFIG_ALPHA_LARGE_VMALLOC
  55#define VMALLOC_START           0xfffffe0000000000
  56#else
  57#define VMALLOC_START           (-2*PGDIR_SIZE)
  58#endif
  59#define VMALLOC_END             (-PGDIR_SIZE)
  60
  61/*
  62 * OSF/1 PAL-code-imposed page table bits
  63 */
  64#define _PAGE_VALID     0x0001
  65#define _PAGE_FOR       0x0002  /* used for page protection (fault on read) */
  66#define _PAGE_FOW       0x0004  /* used for page protection (fault on write) */
  67#define _PAGE_FOE       0x0008  /* used for page protection (fault on exec) */
  68#define _PAGE_ASM       0x0010
  69#define _PAGE_KRE       0x0100  /* xxx - see below on the "accessed" bit */
  70#define _PAGE_URE       0x0200  /* xxx */
  71#define _PAGE_KWE       0x1000  /* used to do the dirty bit in software */
  72#define _PAGE_UWE       0x2000  /* used to do the dirty bit in software */
  73
  74/* .. and these are ours ... */
  75#define _PAGE_DIRTY     0x20000
  76#define _PAGE_ACCESSED  0x40000
  77
  78/*
  79 * NOTE! The "accessed" bit isn't necessarily exact:  it can be kept exactly
  80 * by software (use the KRE/URE/KWE/UWE bits appropriately), but I'll fake it.
  81 * Under Linux/AXP, the "accessed" bit just means "read", and I'll just use
  82 * the KRE/URE bits to watch for it. That way we don't need to overload the
  83 * KWE/UWE bits with both handling dirty and accessed.
  84 *
  85 * Note that the kernel uses the accessed bit just to check whether to page
  86 * out a page or not, so it doesn't have to be exact anyway.
  87 */
  88
  89#define __DIRTY_BITS    (_PAGE_DIRTY | _PAGE_KWE | _PAGE_UWE)
  90#define __ACCESS_BITS   (_PAGE_ACCESSED | _PAGE_KRE | _PAGE_URE)
  91
  92#define _PFN_MASK       0xFFFFFFFF00000000UL
  93
  94#define _PAGE_TABLE     (_PAGE_VALID | __DIRTY_BITS | __ACCESS_BITS)
  95#define _PAGE_CHG_MASK  (_PFN_MASK | __DIRTY_BITS | __ACCESS_BITS)
  96
  97/*
  98 * All the normal masks have the "page accessed" bits on, as any time they are used,
  99 * the page is accessed. They are cleared only by the page-out routines
 100 */
 101#define PAGE_NONE       __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOR | _PAGE_FOW | _PAGE_FOE)
 102#define PAGE_SHARED     __pgprot(_PAGE_VALID | __ACCESS_BITS)
 103#define PAGE_COPY       __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOW)
 104#define PAGE_READONLY   __pgprot(_PAGE_VALID | __ACCESS_BITS | _PAGE_FOW)
 105#define PAGE_KERNEL     __pgprot(_PAGE_VALID | _PAGE_ASM | _PAGE_KRE | _PAGE_KWE)
 106
 107#define _PAGE_NORMAL(x) __pgprot(_PAGE_VALID | __ACCESS_BITS | (x))
 108
 109#define _PAGE_P(x) _PAGE_NORMAL((x) | (((x) & _PAGE_FOW)?0:_PAGE_FOW))
 110#define _PAGE_S(x) _PAGE_NORMAL(x)
 111
 112/*
 113 * The hardware can handle write-only mappings, but as the Alpha
 114 * architecture does byte-wide writes with a read-modify-write
 115 * sequence, it's not practical to have write-without-read privs.
 116 * Thus the "-w- -> rw-" and "-wx -> rwx" mapping here (and in
 117 * arch/alpha/mm/fault.c)
 118 */
 119        /* xwr */
 120#define __P000  _PAGE_P(_PAGE_FOE | _PAGE_FOW | _PAGE_FOR)
 121#define __P001  _PAGE_P(_PAGE_FOE | _PAGE_FOW)
 122#define __P010  _PAGE_P(_PAGE_FOE)
 123#define __P011  _PAGE_P(_PAGE_FOE)
 124#define __P100  _PAGE_P(_PAGE_FOW | _PAGE_FOR)
 125#define __P101  _PAGE_P(_PAGE_FOW)
 126#define __P110  _PAGE_P(0)
 127#define __P111  _PAGE_P(0)
 128
 129#define __S000  _PAGE_S(_PAGE_FOE | _PAGE_FOW | _PAGE_FOR)
 130#define __S001  _PAGE_S(_PAGE_FOE | _PAGE_FOW)
 131#define __S010  _PAGE_S(_PAGE_FOE)
 132#define __S011  _PAGE_S(_PAGE_FOE)
 133#define __S100  _PAGE_S(_PAGE_FOW | _PAGE_FOR)
 134#define __S101  _PAGE_S(_PAGE_FOW)
 135#define __S110  _PAGE_S(0)
 136#define __S111  _PAGE_S(0)
 137
 138/*
 139 * pgprot_noncached() is only for infiniband pci support, and a real
 140 * implementation for RAM would be more complicated.
 141 */
 142#define pgprot_noncached(prot)  (prot)
 143
 144/*
 145 * BAD_PAGETABLE is used when we need a bogus page-table, while
 146 * BAD_PAGE is used for a bogus page.
 147 *
 148 * ZERO_PAGE is a global shared page that is always zero:  used
 149 * for zero-mapped memory areas etc..
 150 */
 151extern pte_t __bad_page(void);
 152extern pmd_t * __bad_pagetable(void);
 153
 154extern unsigned long __zero_page(void);
 155
 156#define BAD_PAGETABLE   __bad_pagetable()
 157#define BAD_PAGE        __bad_page()
 158#define ZERO_PAGE(vaddr)        (virt_to_page(ZERO_PGE))
 159
 160/* number of bits that fit into a memory pointer */
 161#define BITS_PER_PTR                    (8*sizeof(unsigned long))
 162
 163/* to align the pointer to a pointer address */
 164#define PTR_MASK                        (~(sizeof(void*)-1))
 165
 166/* sizeof(void*)==1<<SIZEOF_PTR_LOG2 */
 167#define SIZEOF_PTR_LOG2                 3
 168
 169/* to find an entry in a page-table */
 170#define PAGE_PTR(address)               \
 171  ((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)
 172
 173/*
 174 * On certain platforms whose physical address space can overlap KSEG,
 175 * namely EV6 and above, we must re-twiddle the physaddr to restore the
 176 * correct high-order bits.
 177 *
 178 * This is extremely confusing until you realize that this is actually
 179 * just working around a userspace bug.  The X server was intending to
 180 * provide the physical address but instead provided the KSEG address.
 181 * Or tried to, except it's not representable.
 182 * 
 183 * On Tsunami there's nothing meaningful at 0x40000000000, so this is
 184 * a safe thing to do.  Come the first core logic that does put something
 185 * in this area -- memory or whathaveyou -- then this hack will have
 186 * to go away.  So be prepared!
 187 */
 188
 189#if defined(CONFIG_ALPHA_GENERIC) && defined(USE_48_BIT_KSEG)
 190#error "EV6-only feature in a generic kernel"
 191#endif
 192#if defined(CONFIG_ALPHA_GENERIC) || \
 193    (defined(CONFIG_ALPHA_EV6) && !defined(USE_48_BIT_KSEG))
 194#define KSEG_PFN        (0xc0000000000UL >> PAGE_SHIFT)
 195#define PHYS_TWIDDLE(pfn) \
 196  ((((pfn) & KSEG_PFN) == (0x40000000000UL >> PAGE_SHIFT)) \
 197  ? ((pfn) ^= KSEG_PFN) : (pfn))
 198#else
 199#define PHYS_TWIDDLE(pfn) (pfn)
 200#endif
 201
 202/*
 203 * Conversion functions:  convert a page and protection to a page entry,
 204 * and a page entry and page directory to the page they refer to.
 205 */
 206#ifndef CONFIG_DISCONTIGMEM
 207#define page_to_pa(page)        (((page) - mem_map) << PAGE_SHIFT)
 208
 209#define pte_pfn(pte)    (pte_val(pte) >> 32)
 210#define pte_page(pte)   pfn_to_page(pte_pfn(pte))
 211#define mk_pte(page, pgprot)                                            \
 212({                                                                      \
 213        pte_t pte;                                                      \
 214                                                                        \
 215        pte_val(pte) = (page_to_pfn(page) << 32) | pgprot_val(pgprot);  \
 216        pte;                                                            \
 217})
 218#endif
 219
 220extern inline pte_t pfn_pte(unsigned long physpfn, pgprot_t pgprot)
 221{ pte_t pte; pte_val(pte) = (PHYS_TWIDDLE(physpfn) << 32) | pgprot_val(pgprot); return pte; }
 222
 223extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 224{ pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot); return pte; }
 225
 226extern inline void pmd_set(pmd_t * pmdp, pte_t * ptep)
 227{ pmd_val(*pmdp) = _PAGE_TABLE | ((((unsigned long) ptep) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }
 228
 229extern inline void pgd_set(pgd_t * pgdp, pmd_t * pmdp)
 230{ pgd_val(*pgdp) = _PAGE_TABLE | ((((unsigned long) pmdp) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }
 231
 232
 233extern inline unsigned long
 234pmd_page_vaddr(pmd_t pmd)
 235{
 236        return ((pmd_val(pmd) & _PFN_MASK) >> (32-PAGE_SHIFT)) + PAGE_OFFSET;
 237}
 238
 239#ifndef CONFIG_DISCONTIGMEM
 240#define pmd_page(pmd)   (mem_map + ((pmd_val(pmd) & _PFN_MASK) >> 32))
 241#define pgd_page(pgd)   (mem_map + ((pgd_val(pgd) & _PFN_MASK) >> 32))
 242#endif
 243
 244extern inline unsigned long pgd_page_vaddr(pgd_t pgd)
 245{ return PAGE_OFFSET + ((pgd_val(pgd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
 246
 247extern inline int pte_none(pte_t pte)           { return !pte_val(pte); }
 248extern inline int pte_present(pte_t pte)        { return pte_val(pte) & _PAGE_VALID; }
 249extern inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
 250{
 251        pte_val(*ptep) = 0;
 252}
 253
 254extern inline int pmd_none(pmd_t pmd)           { return !pmd_val(pmd); }
 255extern inline int pmd_bad(pmd_t pmd)            { return (pmd_val(pmd) & ~_PFN_MASK) != _PAGE_TABLE; }
 256extern inline int pmd_present(pmd_t pmd)        { return pmd_val(pmd) & _PAGE_VALID; }
 257extern inline void pmd_clear(pmd_t * pmdp)      { pmd_val(*pmdp) = 0; }
 258
 259extern inline int pgd_none(pgd_t pgd)           { return !pgd_val(pgd); }
 260extern inline int pgd_bad(pgd_t pgd)            { return (pgd_val(pgd) & ~_PFN_MASK) != _PAGE_TABLE; }
 261extern inline int pgd_present(pgd_t pgd)        { return pgd_val(pgd) & _PAGE_VALID; }
 262extern inline void pgd_clear(pgd_t * pgdp)      { pgd_val(*pgdp) = 0; }
 263
 264/*
 265 * The following only work if pte_present() is true.
 266 * Undefined behaviour if not..
 267 */
 268extern inline int pte_write(pte_t pte)          { return !(pte_val(pte) & _PAGE_FOW); }
 269extern inline int pte_dirty(pte_t pte)          { return pte_val(pte) & _PAGE_DIRTY; }
 270extern inline int pte_young(pte_t pte)          { return pte_val(pte) & _PAGE_ACCESSED; }
 271extern inline int pte_special(pte_t pte)        { return 0; }
 272
 273extern inline pte_t pte_wrprotect(pte_t pte)    { pte_val(pte) |= _PAGE_FOW; return pte; }
 274extern inline pte_t pte_mkclean(pte_t pte)      { pte_val(pte) &= ~(__DIRTY_BITS); return pte; }
 275extern inline pte_t pte_mkold(pte_t pte)        { pte_val(pte) &= ~(__ACCESS_BITS); return pte; }
 276extern inline pte_t pte_mkwrite(pte_t pte)      { pte_val(pte) &= ~_PAGE_FOW; return pte; }
 277extern inline pte_t pte_mkdirty(pte_t pte)      { pte_val(pte) |= __DIRTY_BITS; return pte; }
 278extern inline pte_t pte_mkyoung(pte_t pte)      { pte_val(pte) |= __ACCESS_BITS; return pte; }
 279extern inline pte_t pte_mkspecial(pte_t pte)    { return pte; }
 280
 281#define PAGE_DIR_OFFSET(tsk,address) pgd_offset((tsk),(address))
 282
 283/* to find an entry in a kernel page-table-directory */
 284#define pgd_offset_k(address) pgd_offset(&init_mm, (address))
 285
 286/* to find an entry in a page-table-directory. */
 287#define pgd_index(address)      (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
 288#define pgd_offset(mm, address) ((mm)->pgd+pgd_index(address))
 289
 290/*
 291 * The smp_read_barrier_depends() in the following functions are required to
 292 * order the load of *dir (the pointer in the top level page table) with any
 293 * subsequent load of the returned pmd_t *ret (ret is data dependent on *dir).
 294 *
 295 * If this ordering is not enforced, the CPU might load an older value of
 296 * *ret, which may be uninitialized data. See mm/memory.c:__pte_alloc for
 297 * more details.
 298 *
 299 * Note that we never change the mm->pgd pointer after the task is running, so
 300 * pgd_offset does not require such a barrier.
 301 */
 302
 303/* Find an entry in the second-level page table.. */
 304extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
 305{
 306        pmd_t *ret = (pmd_t *) pgd_page_vaddr(*dir) + ((address >> PMD_SHIFT) & (PTRS_PER_PAGE - 1));
 307        smp_read_barrier_depends(); /* see above */
 308        return ret;
 309}
 310
 311/* Find an entry in the third-level page table.. */
 312extern inline pte_t * pte_offset_kernel(pmd_t * dir, unsigned long address)
 313{
 314        pte_t *ret = (pte_t *) pmd_page_vaddr(*dir)
 315                + ((address >> PAGE_SHIFT) & (PTRS_PER_PAGE - 1));
 316        smp_read_barrier_depends(); /* see above */
 317        return ret;
 318}
 319
 320#define pte_offset_map(dir,addr)        pte_offset_kernel((dir),(addr))
 321#define pte_unmap(pte)                  do { } while (0)
 322
 323extern pgd_t swapper_pg_dir[1024];
 324
 325/*
 326 * The Alpha doesn't have any external MMU info:  the kernel page
 327 * tables contain all the necessary information.
 328 */
 329extern inline void update_mmu_cache(struct vm_area_struct * vma,
 330        unsigned long address, pte_t *ptep)
 331{
 332}
 333
 334/*
 335 * Non-present pages:  high 24 bits are offset, next 8 bits type,
 336 * low 32 bits zero.
 337 */
 338extern inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
 339{ pte_t pte; pte_val(pte) = (type << 32) | (offset << 40); return pte; }
 340
 341#define __swp_type(x)           (((x).val >> 32) & 0xff)
 342#define __swp_offset(x)         ((x).val >> 40)
 343#define __swp_entry(type, off)  ((swp_entry_t) { pte_val(mk_swap_pte((type), (off))) })
 344#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
 345#define __swp_entry_to_pte(x)   ((pte_t) { (x).val })
 346
 347#ifndef CONFIG_DISCONTIGMEM
 348#define kern_addr_valid(addr)   (1)
 349#endif
 350
 351#define pte_ERROR(e) \
 352        printk("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e))
 353#define pmd_ERROR(e) \
 354        printk("%s:%d: bad pmd %016lx.\n", __FILE__, __LINE__, pmd_val(e))
 355#define pgd_ERROR(e) \
 356        printk("%s:%d: bad pgd %016lx.\n", __FILE__, __LINE__, pgd_val(e))
 357
 358extern void paging_init(void);
 359
 360#include <asm-generic/pgtable.h>
 361
 362/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
 363#define HAVE_ARCH_UNMAPPED_AREA
 364
 365#endif /* _ALPHA_PGTABLE_H */
 366