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
25 struct mm_struct;
26 struct vm_area_struct;
27
28 extern pgd_t swapper_pg_dir[1024];
29 extern pgd_t initial_page_table[1024];
30 extern pmd_t initial_pg_pmd[];
31
32 void paging_init(void);
33 void 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) \
61 do { \
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 */