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);
36 static inline int pgd_large(pgd_t pgd) { return 0; }
39 * Define this if things work differently on an i386 and an i486:
40 * it will (on an i486) warn about kernel memory accesses that are
41 * done without a 'access_ok(VERIFY_WRITE,..)'
46 # include <asm/pgtable-3level.h>
48 # include <asm/pgtable-2level.h>
51 #if defined(CONFIG_HIGHPTE)
52 #define pte_offset_map(dir, address) \
53 ((pte_t *)kmap_atomic(pmd_page(*(dir))) + \
55 #define pte_unmap(pte) kunmap_atomic((pte))
57 #define pte_offset_map(dir, address) \
58 ((pte_t *)page_address(pmd_page(*(dir))) + pte_index((address)))
59 #define pte_unmap(pte) do { } while (0)
62 /* Clear a kernel PTE and flush it from the TLB */
63 #define kpte_clear_flush(ptep, vaddr) \
65 pte_clear(&init_mm, (vaddr), (ptep)); \
66 __flush_tlb_one_kernel((vaddr)); \
69 #endif /* !__ASSEMBLY__ */
72 * kern_addr_valid() is (1) for FLATMEM and (0) for
73 * SPARSEMEM and DISCONTIGMEM
76 #define kern_addr_valid(addr) (1)
78 #define kern_addr_valid(kaddr) (0)
82 * This is how much memory in addition to the memory covered up to
83 * and including _end we need mapped initially.
85 * (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
86 * (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
88 * Modulo rounding, each megabyte assigned here requires a kilobyte of
89 * memory, which is currently unreclaimed.
91 * This should be a multiple of a page.
93 * KERNEL_IMAGE_SIZE should be greater than pa(_end)
94 * and small than max_low_pfn, otherwise will waste some page table entries
97 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
99 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
103 * Number of possible pages in the lowmem region.
105 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
106 * gas warning about overflowing shift count when gas has been compiled
107 * with only a host target support using a 32-bit type for internal
110 #define LOWMEM_PAGES ((((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))
112 #endif /* _ASM_X86_PGTABLE_32_H */