arch/x86/include/asm/pgtable_32.h

   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 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);
  36
  37 static inline int pgd_large(pgd_t pgd) { return 0; }
  38
  39 /*
  40  * Define this if things work differently on an i386 and an i486:
  41  * it will (on an i486) warn about kernel memory accesses that are
  42  * done without a 'access_ok(VERIFY_WRITE,..)'
  43  */
  44 #undef TEST_ACCESS_OK
  45
  46 #ifdef CONFIG_X86_PAE
  47 # include <asm/pgtable-3level.h>
  48 #else
  49 # include <asm/pgtable-2level.h>
  50 #endif
  51
  52 #if defined(CONFIG_HIGHPTE)
  53 #define pte_offset_map(dir, address)                                    \
  54         ((pte_t *)kmap_atomic(pmd_page(*(dir))) +               \
  55          pte_index((address)))
  56 #define pte_unmap(pte) kunmap_atomic((pte))
  57 #else
  58 #define pte_offset_map(dir, address)                                    \
  59         ((pte_t *)page_address(pmd_page(*(dir))) + pte_index((address)))
  60 #define pte_unmap(pte) do { } while (0)
  61 #endif
  62
  63 /* Clear a kernel PTE and flush it from the TLB */
  64 #define kpte_clear_flush(ptep, vaddr)           \
  65 do {                                            \
  66         pte_clear(&init_mm, (vaddr), (ptep));   \
  67         __flush_tlb_one_kernel((vaddr));                \
  68 } while (0)
  69
  70 #endif /* !__ASSEMBLY__ */
  71
  72 /*
  73  * kern_addr_valid() is (1) for FLATMEM and (0) for
  74  * SPARSEMEM and DISCONTIGMEM
  75  */
  76 #ifdef CONFIG_FLATMEM
  77 #define kern_addr_valid(addr)   (1)
  78 #else
  79 #define kern_addr_valid(kaddr)  (0)
  80 #endif
  81
  82 /*
  83  * This is how much memory in addition to the memory covered up to
  84  * and including _end we need mapped initially.
  85  * We need:
  86  *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
  87  *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
  88  *
  89  * Modulo rounding, each megabyte assigned here requires a kilobyte of
  90  * memory, which is currently unreclaimed.
  91  *
  92  * This should be a multiple of a page.
  93  *
  94  * KERNEL_IMAGE_SIZE should be greater than pa(_end)
  95  * and small than max_low_pfn, otherwise will waste some page table entries
  96  */
  97 #if PTRS_PER_PMD > 1
  98 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
  99 #else
 100 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
 101 #endif
 102
 103 /*
 104  * Number of possible pages in the lowmem region.
 105  *
 106  * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
 107  * gas warning about overflowing shift count when gas has been compiled
 108  * with only a host target support using a 32-bit type for internal
 109  * representation.
 110  */
 111 #define LOWMEM_PAGES ((((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))
 112
 113 #endif /* _ASM_X86_PGTABLE_32_H */