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.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_SWAPPER_USES_SECTION_MAPS 1 22 #else 23 #define ARM64_SWAPPER_USES_SECTION_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_SWAPPER_USES_SECTION_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 + TEXT_OFFSET, _end)) 90 #define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE) 91 92 /* Initial memory map size */ 93 #if ARM64_SWAPPER_USES_SECTION_MAPS 94 #define SWAPPER_BLOCK_SHIFT SECTION_SHIFT 95 #define SWAPPER_BLOCK_SIZE SECTION_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 /* The size of the initial kernel direct mapping */ 104 #define SWAPPER_INIT_MAP_SIZE (_AC(1, UL) << SWAPPER_TABLE_SHIFT) 105 106 /* 107 * Initial memory map attributes. 108 */ 109 #define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) 110 #define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) 111 112 #if ARM64_SWAPPER_USES_SECTION_MAPS 113 #define SWAPPER_MM_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS) 114 #else 115 #define SWAPPER_MM_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS) 116 #endif 117 118 /* 119 * To make optimal use of block mappings when laying out the linear 120 * mapping, round down the base of physical memory to a size that can 121 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE 122 * (64k granule), or a multiple that can be mapped using contiguous bits 123 * in the page tables: 32 * PMD_SIZE (16k granule) 124 */ 125 #if defined(CONFIG_ARM64_4K_PAGES) 126 #define ARM64_MEMSTART_SHIFT PUD_SHIFT 127 #elif defined(CONFIG_ARM64_16K_PAGES) 128 #define ARM64_MEMSTART_SHIFT (PMD_SHIFT + 5) 129 #else 130 #define ARM64_MEMSTART_SHIFT PMD_SHIFT 131 #endif 132 133 /* 134 * sparsemem vmemmap imposes an additional requirement on the alignment of 135 * memstart_addr, due to the fact that the base of the vmemmap region 136 * has a direct correspondence, and needs to appear sufficiently aligned 137 * in the virtual address space. 138 */ 139 #if defined(CONFIG_SPARSEMEM_VMEMMAP) && ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS 140 #define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS) 141 #else 142 #define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT) 143 #endif 144 145 #endif /* __ASM_KERNEL_PGTABLE_H */ 146