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 SPAN_NR_ENTRIES(vstart, vend, shift) \ 63 ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1) 64 65 #define EARLY_ENTRIES(vstart, vend, shift, add) \ 66 (SPAN_NR_ENTRIES(vstart, vend, shift) + (add)) 67 68 #define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add)) 69 70 #if SWAPPER_PGTABLE_LEVELS > 3 71 #define EARLY_PUDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT, add)) 72 #else 73 #define EARLY_PUDS(vstart, vend, add) (0) 74 #endif 75 76 #if SWAPPER_PGTABLE_LEVELS > 2 77 #define EARLY_PMDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT, add)) 78 #else 79 #define EARLY_PMDS(vstart, vend, add) (0) 80 #endif 81 82 #define EARLY_PAGES(vstart, vend, add) ( 1 /* PGDIR page */ \ 83 + EARLY_PGDS((vstart), (vend), add) /* each PGDIR needs a next level page table */ \ 84 + EARLY_PUDS((vstart), (vend), add) /* each PUD needs a next level page table */ \ 85 + EARLY_PMDS((vstart), (vend), add)) /* each PMD needs a next level page table */ 86 #define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end, EARLY_KASLR)) 87 88 /* the initial ID map may need two extra pages if it needs to be extended */ 89 #if VA_BITS < 48 90 #define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE) 91 #else 92 #define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE) 93 #endif 94 #define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE, 1) 95 96 /* Initial memory map size */ 97 #ifdef CONFIG_ARM64_4K_PAGES 98 #define SWAPPER_BLOCK_SHIFT PMD_SHIFT 99 #define SWAPPER_BLOCK_SIZE PMD_SIZE 100 #define SWAPPER_TABLE_SHIFT PUD_SHIFT 101 #else 102 #define SWAPPER_BLOCK_SHIFT PAGE_SHIFT 103 #define SWAPPER_BLOCK_SIZE PAGE_SIZE 104 #define SWAPPER_TABLE_SHIFT PMD_SHIFT 105 #endif 106 107 /* 108 * Initial memory map attributes. 109 */ 110 #define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED | PTE_UXN) 111 #define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PTE_UXN) 112 113 #ifdef CONFIG_ARM64_4K_PAGES 114 #define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS | PTE_WRITE) 115 #define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY) 116 #else 117 #define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS | PTE_WRITE) 118 #define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY) 119 #endif 120 121 #endif /* __ASM_KERNEL_PGTABLE_H */ 122