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 22 /* 23 * The idmap and swapper page tables need some space reserved in the kernel 24 * image. Both require pgd, pud (4 levels only) and pmd tables to (section) 25 * map the kernel. With the 64K page configuration, swapper and idmap need to 26 * map to pte level. The swapper also maps the FDT (see __create_page_tables 27 * for more information). Note that the number of ID map translation levels 28 * could be increased on the fly if system RAM is out of reach for the default 29 * VA range, so pages required to map highest possible PA are reserved in all 30 * cases. 31 */ 32 #ifdef CONFIG_ARM64_4K_PAGES 33 #define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1) 34 #else 35 #define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS) 36 #endif 37 38 39 /* 40 * If KASLR is enabled, then an offset K is added to the kernel address 41 * space. The bottom 21 bits of this offset are zero to guarantee 2MB 42 * alignment for PA and VA. 43 * 44 * For each pagetable level of the swapper, we know that the shift will 45 * be larger than 21 (for the 4KB granule case we use section maps thus 46 * the smallest shift is actually 30) thus there is the possibility that 47 * KASLR can increase the number of pagetable entries by 1, so we make 48 * room for this extra entry. 49 * 50 * Note KASLR cannot increase the number of required entries for a level 51 * by more than one because it increments both the virtual start and end 52 * addresses equally (the extra entry comes from the case where the end 53 * address is just pushed over a boundary and the start address isn't). 54 */ 55 56 #ifdef CONFIG_RANDOMIZE_BASE 57 #define EARLY_KASLR (1) 58 #else 59 #define EARLY_KASLR (0) 60 #endif 61 62 #define EARLY_ENTRIES(vstart, vend, shift, add) \ 63 ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1 + add) 64 65 #define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add)) 66 67 #if SWAPPER_PGTABLE_LEVELS > 3 68 #define EARLY_PUDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT, add)) 69 #else 70 #define EARLY_PUDS(vstart, vend, add) (0) 71 #endif 72 73 #if SWAPPER_PGTABLE_LEVELS > 2 74 #define EARLY_PMDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT, add)) 75 #else 76 #define EARLY_PMDS(vstart, vend, add) (0) 77 #endif 78 79 #define EARLY_PAGES(vstart, vend, add) ( 1 /* PGDIR page */ \ 80 + EARLY_PGDS((vstart), (vend), add) /* each PGDIR needs a next level page table */ \ 81 + EARLY_PUDS((vstart), (vend), add) /* each PUD needs a next level page table */ \ 82 + EARLY_PMDS((vstart), (vend), add)) /* each PMD needs a next level page table */ 83 #define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end, EARLY_KASLR)) 84 85 /* the initial ID map may need two extra pages if it needs to be extended */ 86 #if VA_BITS < 48 87 #define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE) 88 #else 89 #define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE) 90 #endif 91 #define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE, 1) 92 93 /* Initial memory map size */ 94 #ifdef CONFIG_ARM64_4K_PAGES 95 #define SWAPPER_BLOCK_SHIFT PMD_SHIFT 96 #define SWAPPER_BLOCK_SIZE PMD_SIZE 97 #define SWAPPER_TABLE_SHIFT PUD_SHIFT 98 #else 99 #define SWAPPER_BLOCK_SHIFT PAGE_SHIFT 100 #define SWAPPER_BLOCK_SIZE PAGE_SIZE 101 #define SWAPPER_TABLE_SHIFT PMD_SHIFT 102 #endif 103 104 /* 105 * Initial memory map attributes. 106 */ 107 #define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) 108 #define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) 109 110 #ifdef CONFIG_ARM64_4K_PAGES 111 #define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS) 112 #define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY) 113 #else 114 #define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS) 115 #define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY) 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 CONT_PMD_SHIFT 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 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