kernel-pgtable.h (4998B)
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-hwdef.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_KERNEL_USES_PMD_MAPS 1 22#else 23#define ARM64_KERNEL_USES_PMD_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_KERNEL_USES_PMD_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, _end)) 90#define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE) 91 92/* Initial memory map size */ 93#if ARM64_KERNEL_USES_PMD_MAPS 94#define SWAPPER_BLOCK_SHIFT PMD_SHIFT 95#define SWAPPER_BLOCK_SIZE PMD_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/* 104 * Initial memory map attributes. 105 */ 106#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) 107#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) 108 109#if ARM64_KERNEL_USES_PMD_MAPS 110#define SWAPPER_MM_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS) 111#else 112#define SWAPPER_MM_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS) 113#endif 114 115/* 116 * To make optimal use of block mappings when laying out the linear 117 * mapping, round down the base of physical memory to a size that can 118 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE 119 * (64k granule), or a multiple that can be mapped using contiguous bits 120 * in the page tables: 32 * PMD_SIZE (16k granule) 121 */ 122#if defined(CONFIG_ARM64_4K_PAGES) 123#define ARM64_MEMSTART_SHIFT PUD_SHIFT 124#elif defined(CONFIG_ARM64_16K_PAGES) 125#define ARM64_MEMSTART_SHIFT CONT_PMD_SHIFT 126#else 127#define ARM64_MEMSTART_SHIFT PMD_SHIFT 128#endif 129 130/* 131 * sparsemem vmemmap imposes an additional requirement on the alignment of 132 * memstart_addr, due to the fact that the base of the vmemmap region 133 * has a direct correspondence, and needs to appear sufficiently aligned 134 * in the virtual address space. 135 */ 136#if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS 137#define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS) 138#else 139#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT) 140#endif 141 142#endif /* __ASM_KERNEL_PGTABLE_H */