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/boot.h>
  12 #include <asm/pgtable-hwdef.h>
  13 #include <asm/sparsemem.h>
  14
  15 /*
  16  * The physical and virtual addresses of the start of the kernel image are
  17  * equal modulo 2 MiB (per the arm64 booting.txt requirements). Hence we can
  18  * use section mapping with 4K (section size = 2M) but not with 16K (section
  19  * size = 32M) or 64K (section size = 512M).
  20  */
  21 #if defined(PMD_SIZE) && PMD_SIZE <= MIN_KIMG_ALIGN
  22 #define SWAPPER_BLOCK_SHIFT     PMD_SHIFT
  23 #define SWAPPER_SKIP_LEVEL      1
  24 #else
  25 #define SWAPPER_BLOCK_SHIFT     PAGE_SHIFT
  26 #define SWAPPER_SKIP_LEVEL      0
  27 #endif
  28 #define SWAPPER_BLOCK_SIZE      (UL(1) << SWAPPER_BLOCK_SHIFT)
  29
  30 #define SWAPPER_PGTABLE_LEVELS          (CONFIG_PGTABLE_LEVELS - SWAPPER_SKIP_LEVEL)
  31 #define INIT_IDMAP_PGTABLE_LEVELS       (IDMAP_LEVELS - SWAPPER_SKIP_LEVEL)
  32
  33 #define IDMAP_VA_BITS           48
  34 #define IDMAP_LEVELS            ARM64_HW_PGTABLE_LEVELS(IDMAP_VA_BITS)
  35 #define IDMAP_ROOT_LEVEL        (4 - IDMAP_LEVELS)
  36
  37 /*
  38  * A relocatable kernel may execute from an address that differs from the one at
  39  * which it was linked. In the worst case, its runtime placement may intersect
  40  * with two adjacent PGDIR entries, which means that an additional page table
  41  * may be needed at each subordinate level.
  42  */
  43 #define EXTRA_PAGE      __is_defined(CONFIG_RELOCATABLE)
  44
  45 #define SPAN_NR_ENTRIES(vstart, vend, shift) \
  46         ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1)
  47
  48 #define EARLY_ENTRIES(vstart, vend, shift, add) \
  49         (SPAN_NR_ENTRIES(vstart, vend, shift) + (add))
  50
  51 #define EARLY_LEVEL(lvl, lvls, vstart, vend, add)       \
  52         (lvls > lvl ? EARLY_ENTRIES(vstart, vend, SWAPPER_BLOCK_SHIFT + lvl * (PAGE_SHIFT - 3), add) : 0)
  53
  54 #define EARLY_PAGES(lvls, vstart, vend, add) (1         /* PGDIR page */                                \
  55         + EARLY_LEVEL(3, (lvls), (vstart), (vend), add) /* each entry needs a next level page table */  \
  56         + EARLY_LEVEL(2, (lvls), (vstart), (vend), add) /* each entry needs a next level page table */  \
  57         + EARLY_LEVEL(1, (lvls), (vstart), (vend), add))/* each entry needs a next level page table */
  58 #define INIT_DIR_SIZE (PAGE_SIZE * (EARLY_PAGES(SWAPPER_PGTABLE_LEVELS, KIMAGE_VADDR, _end, EXTRA_PAGE) \
  59                                     + EARLY_SEGMENT_EXTRA_PAGES))
  60
  61 #define INIT_IDMAP_DIR_PAGES    (EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, KIMAGE_VADDR, _end, 1))
  62 #define INIT_IDMAP_DIR_SIZE     ((INIT_IDMAP_DIR_PAGES + EARLY_IDMAP_EXTRA_PAGES) * PAGE_SIZE)
  63
  64 #define INIT_IDMAP_FDT_PAGES    (EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, 0UL, UL(MAX_FDT_SIZE), 1) - 1)
  65 #define INIT_IDMAP_FDT_SIZE     ((INIT_IDMAP_FDT_PAGES + EARLY_IDMAP_EXTRA_FDT_PAGES) * PAGE_SIZE)
  66
  67 /* The number of segments in the kernel image (text, rodata, inittext, initdata, data+bss) */
  68 #define KERNEL_SEGMENT_COUNT    5
  69
  70 #if SWAPPER_BLOCK_SIZE > SEGMENT_ALIGN
  71 #define EARLY_SEGMENT_EXTRA_PAGES (KERNEL_SEGMENT_COUNT + 1)
  72 /*
  73  * The initial ID map consists of the kernel image, mapped as two separate
  74  * segments, and may appear misaligned wrt the swapper block size. This means
  75  * we need 3 additional pages. The DT could straddle a swapper block boundary,
  76  * so it may need 2.
  77  */
  78 #define EARLY_IDMAP_EXTRA_PAGES         3
  79 #define EARLY_IDMAP_EXTRA_FDT_PAGES     2
  80 #else
  81 #define EARLY_SEGMENT_EXTRA_PAGES       0
  82 #define EARLY_IDMAP_EXTRA_PAGES         0
  83 #define EARLY_IDMAP_EXTRA_FDT_PAGES     0
  84 #endif
  85
  86 #endif  /* __ASM_KERNEL_PGTABLE_H */