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 __ASSEMBLER__
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#ifdef CONFIG_X86_PAE
36# include <asm/pgtable-3level.h>
37#else
38# include <asm/pgtable-2level.h>
39#endif
40
41/* Clear a kernel PTE and flush it from the TLB */
42#define kpte_clear_flush(ptep, vaddr) \
43do { \
44 pte_clear(&init_mm, (vaddr), (ptep)); \
45 flush_tlb_one_kernel((vaddr)); \
46} while (0)
47
48#endif /* !__ASSEMBLER__ */
49
50/*
51 * This is used to calculate the .brk reservation for initial pagetables.
52 * Enough space is reserved to allocate pagetables sufficient to cover all
53 * of LOWMEM_PAGES, which is an upper bound on the size of the direct map of
54 * lowmem.
55 *
56 * With PAE paging (PTRS_PER_PMD > 1), we allocate PTRS_PER_PGD == 4 pages for
57 * the PMD's in addition to the pages required for the last level pagetables.
58 */
59#if PTRS_PER_PMD > 1
60#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
61#else
62#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
63#endif
64
65/*
66 * Number of possible pages in the lowmem region.
67 *
68 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
69 * gas warning about overflowing shift count when gas has been compiled
70 * with only a host target support using a 32-bit type for internal
71 * representation.
72 */
73#define LOWMEM_PAGES ((((_ULL(2)<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))
74
75#endif /* _ASM_X86_PGTABLE_32_H */
76

source code of linux/arch/x86/include/asm/pgtable_32.h