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 linear mapping and the start of memory are both 2M aligned (per 17 * the arm64 booting.txt requirements). Hence we can use section mapping 18 * with 4K (section size = 2M) but not with 16K (section size = 32M) or 19 * 64K (section size = 512M). 20 */ 21 #ifdef CONFIG_ARM64_4K_PAGES 22 #define ARM64_KERNEL_USES_PMD_MAPS 1 23 #else 24 #define ARM64_KERNEL_USES_PMD_MAPS 0 25 #endif 26 27 /* 28 * The idmap and swapper page tables need some space reserved in the kernel 29 * image. Both require pgd, pud (4 levels only) and pmd tables to (section) 30 * map the kernel. With the 64K page configuration, swapper and idmap need to 31 * map to pte level. The swapper also maps the FDT (see __create_page_tables 32 * for more information). Note that the number of ID map translation levels 33 * could be increased on the fly if system RAM is out of reach for the default 34 * VA range, so pages required to map highest possible PA are reserved in all 35 * cases. 36 */ 37 #if ARM64_KERNEL_USES_PMD_MAPS 38 #define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1) 39 #else 40 #define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS) 41 #endif 42 43 44 /* 45 * If KASLR is enabled, then an offset K is added to the kernel address 46 * space. The bottom 21 bits of this offset are zero to guarantee 2MB 47 * alignment for PA and VA. 48 * 49 * For each pagetable level of the swapper, we know that the shift will 50 * be larger than 21 (for the 4KB granule case we use section maps thus 51 * the smallest shift is actually 30) thus there is the possibility that 52 * KASLR can increase the number of pagetable entries by 1, so we make 53 * room for this extra entry. 54 * 55 * Note KASLR cannot increase the number of required entries for a level 56 * by more than one because it increments both the virtual start and end 57 * addresses equally (the extra entry comes from the case where the end 58 * address is just pushed over a boundary and the start address isn't). 59 */ 60 61 #ifdef CONFIG_RANDOMIZE_BASE 62 #define EARLY_KASLR (1) 63 #else 64 #define EARLY_KASLR (0) 65 #endif 66 67 #define EARLY_ENTRIES(vstart, vend, shift, add) \ 68 ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1 + add) 69 70 #define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add)) 71 72 #if SWAPPER_PGTABLE_LEVELS > 3 73 #define EARLY_PUDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT, add)) 74 #else 75 #define EARLY_PUDS(vstart, vend, add) (0) 76 #endif 77 78 #if SWAPPER_PGTABLE_LEVELS > 2 79 #define EARLY_PMDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT, add)) 80 #else 81 #define EARLY_PMDS(vstart, vend, add) (0) 82 #endif 83 84 #define EARLY_PAGES(vstart, vend, add) ( 1 /* PGDIR page */ \ 85 + EARLY_PGDS((vstart), (vend), add) /* each PGDIR needs a next level page table */ \ 86 + EARLY_PUDS((vstart), (vend), add) /* each PUD needs a next level page table */ \ 87 + EARLY_PMDS((vstart), (vend), add)) /* each PMD needs a next level page table */ 88 #define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end, EARLY_KASLR)) 89 90 /* the initial ID map may need two extra pages if it needs to be extended */ 91 #if VA_BITS < 48 92 #define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE) 93 #else 94 #define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE) 95 #endif 96 #define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE, 1) 97 98 /* Initial memory map size */ 99 #if ARM64_KERNEL_USES_PMD_MAPS 100 #define SWAPPER_BLOCK_SHIFT PMD_SHIFT 101 #define SWAPPER_BLOCK_SIZE PMD_SIZE 102 #define SWAPPER_TABLE_SHIFT PUD_SHIFT 103 #else 104 #define SWAPPER_BLOCK_SHIFT PAGE_SHIFT 105 #define SWAPPER_BLOCK_SIZE PAGE_SIZE 106 #define SWAPPER_TABLE_SHIFT PMD_SHIFT 107 #endif 108 109 /* 110 * Initial memory map attributes. 111 */ 112 #define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) 113 #define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) 114 115 #if ARM64_KERNEL_USES_PMD_MAPS 116 #define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS) 117 #define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY) 118 #else 119 #define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS) 120 #define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY) 121 #endif 122 123 /* 124 * To make optimal use of block mappings when laying out the linear 125 * mapping, round down the base of physical memory to a size that can 126 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE 127 * (64k granule), or a multiple that can be mapped using contiguous bits 128 * in the page tables: 32 * PMD_SIZE (16k granule) 129 */ 130 #if defined(CONFIG_ARM64_4K_PAGES) 131 #define ARM64_MEMSTART_SHIFT PUD_SHIFT 132 #elif defined(CONFIG_ARM64_16K_PAGES) 133 #define ARM64_MEMSTART_SHIFT CONT_PMD_SHIFT 134 #else 135 #define ARM64_MEMSTART_SHIFT PMD_SHIFT 136 #endif 137 138 /* 139 * sparsemem vmemmap imposes an additional requirement on the alignment of 140 * memstart_addr, due to the fact that the base of the vmemmap region 141 * has a direct correspondence, and needs to appear sufficiently aligned 142 * in the virtual address space. 143 */ 144 #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS 145 #define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS) 146 #else 147 #define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT) 148 #endif 149 150 #endif /* __ASM_KERNEL_PGTABLE_H */ 151