linux/arch/x86/include/asm/pgtable_32.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_X86_PGTABLE_32_H
   3#define _ASM_X86_PGTABLE_32_H
   4
   5#include <asm/pgtable_32_types.h>
   6
   7/*
   8 * The Linux memory management assumes a three-level page table setup. On
   9 * the i386, we use that, but "fold" the mid level into the top-level page
  10 * table, so that we physically have the same two-level page table as the
  11 * i386 mmu expects.
  12 *
  13 * This file contains the functions and defines necessary to modify and use
  14 * the i386 page table tree.
  15 */
  16#ifndef __ASSEMBLY__
  17#include <asm/processor.h>
  18#include <linux/threads.h>
  19#include <asm/paravirt.h>
  20
  21#include <linux/bitops.h>
  22#include <linux/list.h>
  23#include <linux/spinlock.h>
  24
  25struct mm_struct;
  26struct vm_area_struct;
  27
  28extern pgd_t swapper_pg_dir[1024];
  29extern pgd_t initial_page_table[1024];
  30extern pmd_t initial_pg_pmd[];
  31
  32void paging_init(void);
  33void sync_initial_page_table(void);
  34
  35/*
  36 * Define this if things work differently on an i386 and an i486:
  37 * it will (on an i486) warn about kernel memory accesses that are
  38 * done without a 'access_ok( ..)'
  39 */
  40#undef TEST_ACCESS_OK
  41
  42#ifdef CONFIG_X86_PAE
  43# include <asm/pgtable-3level.h>
  44#else
  45# include <asm/pgtable-2level.h>
  46#endif
  47
  48#if defined(CONFIG_HIGHPTE)
  49#define pte_offset_map(dir, address)                                    \
  50        ((pte_t *)kmap_atomic(pmd_page(*(dir))) +               \
  51         pte_index((address)))
  52#define pte_unmap(pte) kunmap_atomic((pte))
  53#else
  54#define pte_offset_map(dir, address)                                    \
  55        ((pte_t *)page_address(pmd_page(*(dir))) + pte_index((address)))
  56#define pte_unmap(pte) do { } while (0)
  57#endif
  58
  59/* Clear a kernel PTE and flush it from the TLB */
  60#define kpte_clear_flush(ptep, vaddr)           \
  61do {                                            \
  62        pte_clear(&init_mm, (vaddr), (ptep));   \
  63        __flush_tlb_one_kernel((vaddr));                \
  64} while (0)
  65
  66#endif /* !__ASSEMBLY__ */
  67
  68/*
  69 * kern_addr_valid() is (1) for FLATMEM and (0) for
  70 * SPARSEMEM and DISCONTIGMEM
  71 */
  72#ifdef CONFIG_FLATMEM
  73#define kern_addr_valid(addr)   (1)
  74#else
  75#define kern_addr_valid(kaddr)  (0)
  76#endif
  77
  78/*
  79 * This is how much memory in addition to the memory covered up to
  80 * and including _end we need mapped initially.
  81 * We need:
  82 *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
  83 *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
  84 *
  85 * Modulo rounding, each megabyte assigned here requires a kilobyte of
  86 * memory, which is currently unreclaimed.
  87 *
  88 * This should be a multiple of a page.
  89 *
  90 * KERNEL_IMAGE_SIZE should be greater than pa(_end)
  91 * and small than max_low_pfn, otherwise will waste some page table entries
  92 */
  93#if PTRS_PER_PMD > 1
  94#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
  95#else
  96#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
  97#endif
  98
  99/*
 100 * Number of possible pages in the lowmem region.
 101 *
 102 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
 103 * gas warning about overflowing shift count when gas has been compiled
 104 * with only a host target support using a 32-bit type for internal
 105 * representation.
 106 */
 107#define LOWMEM_PAGES ((((_ULL(2)<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))
 108
 109#endif /* _ASM_X86_PGTABLE_32_H */
 110