arch/arm64/include/asm/kernel-pgtable.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Kernel page table mapping
   4  *
   5  * Copyright (C) 2015 ARM Ltd.
   6  */
   7
   8 #ifndef __ASM_KERNEL_PGTABLE_H
   9 #define __ASM_KERNEL_PGTABLE_H
  10
  11 #include <asm/pgtable-hwdef.h>
  12 #include <asm/sparsemem.h>
  13
  14 /*
  15  * The linear mapping and the start of memory are both 2M aligned (per
  16  * the arm64 booting.txt requirements). Hence we can use section mapping
  17  * with 4K (section size = 2M) but not with 16K (section size = 32M) or
  18  * 64K (section size = 512M).
  19  */
  20 #ifdef CONFIG_ARM64_4K_PAGES
  21 #define ARM64_KERNEL_USES_PMD_MAPS 1
  22 #else
  23 #define ARM64_KERNEL_USES_PMD_MAPS 0
  24 #endif
  25
  26 /*
  27  * The idmap and swapper page tables need some space reserved in the kernel
  28  * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
  29  * map the kernel. With the 64K page configuration, swapper and idmap need to
  30  * map to pte level. The swapper also maps the FDT (see __create_page_tables
  31  * for more information). Note that the number of ID map translation levels
  32  * could be increased on the fly if system RAM is out of reach for the default
  33  * VA range, so pages required to map highest possible PA are reserved in all
  34  * cases.
  35  */
  36 #if ARM64_KERNEL_USES_PMD_MAPS
  37 #define SWAPPER_PGTABLE_LEVELS  (CONFIG_PGTABLE_LEVELS - 1)
  38 #define IDMAP_PGTABLE_LEVELS    (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT) - 1)
  39 #else
  40 #define SWAPPER_PGTABLE_LEVELS  (CONFIG_PGTABLE_LEVELS)
  41 #define IDMAP_PGTABLE_LEVELS    (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
  42 #endif
  43
  44
  45 /*
  46  * If KASLR is enabled, then an offset K is added to the kernel address
  47  * space. The bottom 21 bits of this offset are zero to guarantee 2MB
  48  * alignment for PA and VA.
  49  *
  50  * For each pagetable level of the swapper, we know that the shift will
  51  * be larger than 21 (for the 4KB granule case we use section maps thus
  52  * the smallest shift is actually 30) thus there is the possibility that
  53  * KASLR can increase the number of pagetable entries by 1, so we make
  54  * room for this extra entry.
  55  *
  56  * Note KASLR cannot increase the number of required entries for a level
  57  * by more than one because it increments both the virtual start and end
  58  * addresses equally (the extra entry comes from the case where the end
  59  * address is just pushed over a boundary and the start address isn't).
  60  */
  61
  62 #ifdef CONFIG_RANDOMIZE_BASE
  63 #define EARLY_KASLR     (1)
  64 #else
  65 #define EARLY_KASLR     (0)
  66 #endif
  67
  68 #define EARLY_ENTRIES(vstart, vend, shift) \
  69         ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1 + EARLY_KASLR)
  70
  71 #define EARLY_PGDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT))
  72
  73 #if SWAPPER_PGTABLE_LEVELS > 3
  74 #define EARLY_PUDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT))
  75 #else
  76 #define EARLY_PUDS(vstart, vend) (0)
  77 #endif
  78
  79 #if SWAPPER_PGTABLE_LEVELS > 2
  80 #define EARLY_PMDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT))
  81 #else
  82 #define EARLY_PMDS(vstart, vend) (0)
  83 #endif
  84
  85 #define EARLY_PAGES(vstart, vend) ( 1                   /* PGDIR page */                                \
  86                         + EARLY_PGDS((vstart), (vend))  /* each PGDIR needs a next level page table */  \
  87                         + EARLY_PUDS((vstart), (vend))  /* each PUD needs a next level page table */    \
  88                         + EARLY_PMDS((vstart), (vend))) /* each PMD needs a next level page table */
  89 #define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end))
  90 #define IDMAP_DIR_SIZE          (IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
  91
  92 /* Initial memory map size */
  93 #if ARM64_KERNEL_USES_PMD_MAPS
  94 #define SWAPPER_BLOCK_SHIFT     PMD_SHIFT
  95 #define SWAPPER_BLOCK_SIZE      PMD_SIZE
  96 #define SWAPPER_TABLE_SHIFT     PUD_SHIFT
  97 #else
  98 #define SWAPPER_BLOCK_SHIFT     PAGE_SHIFT
  99 #define SWAPPER_BLOCK_SIZE      PAGE_SIZE
 100 #define SWAPPER_TABLE_SHIFT     PMD_SHIFT
 101 #endif
 102
 103 /*
 104  * Initial memory map attributes.
 105  */
 106 #define SWAPPER_PTE_FLAGS       (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED | PTE_UXN)
 107 #define SWAPPER_PMD_FLAGS       (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PMD_SECT_UXN)
 108
 109 #if ARM64_KERNEL_USES_PMD_MAPS
 110 #define SWAPPER_MM_MMUFLAGS     (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
 111 #else
 112 #define SWAPPER_MM_MMUFLAGS     (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
 113 #endif
 114
 115 /*
 116  * To make optimal use of block mappings when laying out the linear
 117  * mapping, round down the base of physical memory to a size that can
 118  * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
 119  * (64k granule), or a multiple that can be mapped using contiguous bits
 120  * in the page tables: 32 * PMD_SIZE (16k granule)
 121  */
 122 #if defined(CONFIG_ARM64_4K_PAGES)
 123 #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
 124 #elif defined(CONFIG_ARM64_16K_PAGES)
 125 #define ARM64_MEMSTART_SHIFT            CONT_PMD_SHIFT
 126 #else
 127 #define ARM64_MEMSTART_SHIFT            PMD_SHIFT
 128 #endif
 129
 130 /*
 131  * sparsemem vmemmap imposes an additional requirement on the alignment of
 132  * memstart_addr, due to the fact that the base of the vmemmap region
 133  * has a direct correspondence, and needs to appear sufficiently aligned
 134  * in the virtual address space.
 135  */
 136 #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
 137 #define ARM64_MEMSTART_ALIGN    (1UL << SECTION_SIZE_BITS)
 138 #else
 139 #define ARM64_MEMSTART_ALIGN    (1UL << ARM64_MEMSTART_SHIFT)
 140 #endif
 141
 142 #endif  /* __ASM_KERNEL_PGTABLE_H */