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

   1 /*
   2  * Kernel page table mapping
   3  *
   4  * Copyright (C) 2015 ARM Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #ifndef __ASM_KERNEL_PGTABLE_H
  20 #define __ASM_KERNEL_PGTABLE_H
  21
  22 #include <asm/pgtable.h>
  23 #include <asm/sparsemem.h>
  24
  25 /*
  26  * The linear mapping and the start of memory are both 2M aligned (per
  27  * the arm64 booting.txt requirements). Hence we can use section mapping
  28  * with 4K (section size = 2M) but not with 16K (section size = 32M) or
  29  * 64K (section size = 512M).
  30  */
  31 #ifdef CONFIG_ARM64_4K_PAGES
  32 #define ARM64_SWAPPER_USES_SECTION_MAPS 1
  33 #else
  34 #define ARM64_SWAPPER_USES_SECTION_MAPS 0
  35 #endif
  36
  37 /*
  38  * The idmap and swapper page tables need some space reserved in the kernel
  39  * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
  40  * map the kernel. With the 64K page configuration, swapper and idmap need to
  41  * map to pte level. The swapper also maps the FDT (see __create_page_tables
  42  * for more information). Note that the number of ID map translation levels
  43  * could be increased on the fly if system RAM is out of reach for the default
  44  * VA range, so pages required to map highest possible PA are reserved in all
  45  * cases.
  46  */
  47 #if ARM64_SWAPPER_USES_SECTION_MAPS
  48 #define SWAPPER_PGTABLE_LEVELS  (CONFIG_PGTABLE_LEVELS - 1)
  49 #define IDMAP_PGTABLE_LEVELS    (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT) - 1)
  50 #else
  51 #define SWAPPER_PGTABLE_LEVELS  (CONFIG_PGTABLE_LEVELS)
  52 #define IDMAP_PGTABLE_LEVELS    (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
  53 #endif
  54
  55
  56 /*
  57  * If KASLR is enabled, then an offset K is added to the kernel address
  58  * space. The bottom 21 bits of this offset are zero to guarantee 2MB
  59  * alignment for PA and VA.
  60  *
  61  * For each pagetable level of the swapper, we know that the shift will
  62  * be larger than 21 (for the 4KB granule case we use section maps thus
  63  * the smallest shift is actually 30) thus there is the possibility that
  64  * KASLR can increase the number of pagetable entries by 1, so we make
  65  * room for this extra entry.
  66  *
  67  * Note KASLR cannot increase the number of required entries for a level
  68  * by more than one because it increments both the virtual start and end
  69  * addresses equally (the extra entry comes from the case where the end
  70  * address is just pushed over a boundary and the start address isn't).
  71  */
  72
  73 #ifdef CONFIG_RANDOMIZE_BASE
  74 #define EARLY_KASLR     (1)
  75 #else
  76 #define EARLY_KASLR     (0)
  77 #endif
  78
  79 #define EARLY_ENTRIES(vstart, vend, shift) (((vend) >> (shift)) \
  80                                         - ((vstart) >> (shift)) + 1 + EARLY_KASLR)
  81
  82 #define EARLY_PGDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT))
  83
  84 #if SWAPPER_PGTABLE_LEVELS > 3
  85 #define EARLY_PUDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT))
  86 #else
  87 #define EARLY_PUDS(vstart, vend) (0)
  88 #endif
  89
  90 #if SWAPPER_PGTABLE_LEVELS > 2
  91 #define EARLY_PMDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT))
  92 #else
  93 #define EARLY_PMDS(vstart, vend) (0)
  94 #endif
  95
  96 #define EARLY_PAGES(vstart, vend) ( 1                   /* PGDIR page */                                \
  97                         + EARLY_PGDS((vstart), (vend))  /* each PGDIR needs a next level page table */  \
  98                         + EARLY_PUDS((vstart), (vend))  /* each PUD needs a next level page table */    \
  99                         + EARLY_PMDS((vstart), (vend))) /* each PMD needs a next level page table */
 100 #define SWAPPER_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR + TEXT_OFFSET, _end))
 101 #define IDMAP_DIR_SIZE          (IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
 102
 103 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 104 #define RESERVED_TTBR0_SIZE     (PAGE_SIZE)
 105 #else
 106 #define RESERVED_TTBR0_SIZE     (0)
 107 #endif
 108
 109 /* Initial memory map size */
 110 #if ARM64_SWAPPER_USES_SECTION_MAPS
 111 #define SWAPPER_BLOCK_SHIFT     SECTION_SHIFT
 112 #define SWAPPER_BLOCK_SIZE      SECTION_SIZE
 113 #define SWAPPER_TABLE_SHIFT     PUD_SHIFT
 114 #else
 115 #define SWAPPER_BLOCK_SHIFT     PAGE_SHIFT
 116 #define SWAPPER_BLOCK_SIZE      PAGE_SIZE
 117 #define SWAPPER_TABLE_SHIFT     PMD_SHIFT
 118 #endif
 119
 120 /* The size of the initial kernel direct mapping */
 121 #define SWAPPER_INIT_MAP_SIZE   (_AC(1, UL) << SWAPPER_TABLE_SHIFT)
 122
 123 /*
 124  * Initial memory map attributes.
 125  */
 126 #define SWAPPER_PTE_FLAGS       (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
 127 #define SWAPPER_PMD_FLAGS       (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
 128
 129 #if ARM64_SWAPPER_USES_SECTION_MAPS
 130 #define SWAPPER_MM_MMUFLAGS     (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
 131 #else
 132 #define SWAPPER_MM_MMUFLAGS     (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
 133 #endif
 134
 135 /*
 136  * To make optimal use of block mappings when laying out the linear
 137  * mapping, round down the base of physical memory to a size that can
 138  * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
 139  * (64k granule), or a multiple that can be mapped using contiguous bits
 140  * in the page tables: 32 * PMD_SIZE (16k granule)
 141  */
 142 #if defined(CONFIG_ARM64_4K_PAGES)
 143 #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
 144 #elif defined(CONFIG_ARM64_16K_PAGES)
 145 #define ARM64_MEMSTART_SHIFT            (PMD_SHIFT + 5)
 146 #else
 147 #define ARM64_MEMSTART_SHIFT            PMD_SHIFT
 148 #endif
 149
 150 /*
 151  * sparsemem vmemmap imposes an additional requirement on the alignment of
 152  * memstart_addr, due to the fact that the base of the vmemmap region
 153  * has a direct correspondence, and needs to appear sufficiently aligned
 154  * in the virtual address space.
 155  */
 156 #if defined(CONFIG_SPARSEMEM_VMEMMAP) && ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
 157 #define ARM64_MEMSTART_ALIGN    (1UL << SECTION_SIZE_BITS)
 158 #else
 159 #define ARM64_MEMSTART_ALIGN    (1UL << ARM64_MEMSTART_SHIFT)
 160 #endif
 161
 162 #endif  /* __ASM_KERNEL_PGTABLE_H */