1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_PGTABLE_32_H
3 #define _ASM_X86_PGTABLE_32_H
5 #include <asm/pgtable_32_types.h>
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
13 * This file contains the functions and defines necessary to modify and use
14 * the i386 page table tree.
17 #include <asm/processor.h>
18 #include <linux/threads.h>
19 #include <asm/paravirt.h>
21 #include <linux/bitops.h>
22 #include <linux/list.h>
23 #include <linux/spinlock.h>
26 struct vm_area_struct
;
28 extern pgd_t swapper_pg_dir
[1024];
29 extern pgd_t initial_page_table
[1024];
30 extern pmd_t initial_pg_pmd
[];
32 static inline void pgtable_cache_init(void) { }
33 static inline void check_pgt_cache(void) { }
34 void paging_init(void);
35 void sync_initial_page_table(void);
38 * Define this if things work differently on an i386 and an i486:
39 * it will (on an i486) warn about kernel memory accesses that are
40 * done without a 'access_ok( ..)'
45 # include <asm/pgtable-3level.h>
47 # include <asm/pgtable-2level.h>
50 #if defined(CONFIG_HIGHPTE)
51 #define pte_offset_map(dir, address) \
52 ((pte_t *)kmap_atomic(pmd_page(*(dir))) + \
54 #define pte_unmap(pte) kunmap_atomic((pte))
56 #define pte_offset_map(dir, address) \
57 ((pte_t *)page_address(pmd_page(*(dir))) + pte_index((address)))
58 #define pte_unmap(pte) do { } while (0)
61 /* Clear a kernel PTE and flush it from the TLB */
62 #define kpte_clear_flush(ptep, vaddr) \
64 pte_clear(&init_mm, (vaddr), (ptep)); \
65 __flush_tlb_one_kernel((vaddr)); \
68 #endif /* !__ASSEMBLY__ */
71 * kern_addr_valid() is (1) for FLATMEM and (0) for
72 * SPARSEMEM and DISCONTIGMEM
75 #define kern_addr_valid(addr) (1)
77 #define kern_addr_valid(kaddr) (0)
81 * This is how much memory in addition to the memory covered up to
82 * and including _end we need mapped initially.
84 * (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
85 * (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
87 * Modulo rounding, each megabyte assigned here requires a kilobyte of
88 * memory, which is currently unreclaimed.
90 * This should be a multiple of a page.
92 * KERNEL_IMAGE_SIZE should be greater than pa(_end)
93 * and small than max_low_pfn, otherwise will waste some page table entries
96 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
98 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
102 * Number of possible pages in the lowmem region.
104 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
105 * gas warning about overflowing shift count when gas has been compiled
106 * with only a host target support using a 32-bit type for internal
109 #define LOWMEM_PAGES ((((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))
111 #endif /* _ASM_X86_PGTABLE_32_H */