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Diffstat (limited to 'arch/arm64/include/asm/kernel-pgtable.h')
| -rw-r--r-- | arch/arm64/include/asm/kernel-pgtable.h | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h new file mode 100644 index 000000000..32d14f481 --- /dev/null +++ b/arch/arm64/include/asm/kernel-pgtable.h @@ -0,0 +1,150 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Kernel page table mapping + * + * Copyright (C) 2015 ARM Ltd. + */ + +#ifndef __ASM_KERNEL_PGTABLE_H +#define __ASM_KERNEL_PGTABLE_H + +#include <asm/boot.h> +#include <asm/pgtable-hwdef.h> +#include <asm/sparsemem.h> + +/* + * The linear mapping and the start of memory are both 2M aligned (per + * the arm64 booting.txt requirements). Hence we can use section mapping + * with 4K (section size = 2M) but not with 16K (section size = 32M) or + * 64K (section size = 512M). + */ +#ifdef CONFIG_ARM64_4K_PAGES +#define ARM64_KERNEL_USES_PMD_MAPS 1 +#else +#define ARM64_KERNEL_USES_PMD_MAPS 0 +#endif + +/* + * The idmap and swapper page tables need some space reserved in the kernel + * image. Both require pgd, pud (4 levels only) and pmd tables to (section) + * map the kernel. With the 64K page configuration, swapper and idmap need to + * map to pte level. The swapper also maps the FDT (see __create_page_tables + * for more information). Note that the number of ID map translation levels + * could be increased on the fly if system RAM is out of reach for the default + * VA range, so pages required to map highest possible PA are reserved in all + * cases. + */ +#if ARM64_KERNEL_USES_PMD_MAPS +#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1) +#else +#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS) +#endif + + +/* + * If KASLR is enabled, then an offset K is added to the kernel address + * space. The bottom 21 bits of this offset are zero to guarantee 2MB + * alignment for PA and VA. + * + * For each pagetable level of the swapper, we know that the shift will + * be larger than 21 (for the 4KB granule case we use section maps thus + * the smallest shift is actually 30) thus there is the possibility that + * KASLR can increase the number of pagetable entries by 1, so we make + * room for this extra entry. + * + * Note KASLR cannot increase the number of required entries for a level + * by more than one because it increments both the virtual start and end + * addresses equally (the extra entry comes from the case where the end + * address is just pushed over a boundary and the start address isn't). + */ + +#ifdef CONFIG_RANDOMIZE_BASE +#define EARLY_KASLR (1) +#else +#define EARLY_KASLR (0) +#endif + +#define EARLY_ENTRIES(vstart, vend, shift, add) \ + ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1 + add) + +#define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add)) + +#if SWAPPER_PGTABLE_LEVELS > 3 +#define EARLY_PUDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT, add)) +#else +#define EARLY_PUDS(vstart, vend, add) (0) +#endif + +#if SWAPPER_PGTABLE_LEVELS > 2 +#define EARLY_PMDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT, add)) +#else +#define EARLY_PMDS(vstart, vend, add) (0) +#endif + +#define EARLY_PAGES(vstart, vend, add) ( 1 /* PGDIR page */ \ + + EARLY_PGDS((vstart), (vend), add) /* each PGDIR needs a next level page table */ \ + + EARLY_PUDS((vstart), (vend), add) /* each PUD needs a next level page table */ \ + + EARLY_PMDS((vstart), (vend), add)) /* each PMD needs a next level page table */ +#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end, EARLY_KASLR)) + +/* the initial ID map may need two extra pages if it needs to be extended */ +#if VA_BITS < 48 +#define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE) +#else +#define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE) +#endif +#define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE, 1) + +/* Initial memory map size */ +#if ARM64_KERNEL_USES_PMD_MAPS +#define SWAPPER_BLOCK_SHIFT PMD_SHIFT +#define SWAPPER_BLOCK_SIZE PMD_SIZE +#define SWAPPER_TABLE_SHIFT PUD_SHIFT +#else +#define SWAPPER_BLOCK_SHIFT PAGE_SHIFT +#define SWAPPER_BLOCK_SIZE PAGE_SIZE +#define SWAPPER_TABLE_SHIFT PMD_SHIFT +#endif + +/* + * Initial memory map attributes. + */ +#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) +#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) + +#if ARM64_KERNEL_USES_PMD_MAPS +#define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS) +#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY) +#else +#define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS) +#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY) +#endif + +/* + * To make optimal use of block mappings when laying out the linear + * mapping, round down the base of physical memory to a size that can + * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE + * (64k granule), or a multiple that can be mapped using contiguous bits + * in the page tables: 32 * PMD_SIZE (16k granule) + */ +#if defined(CONFIG_ARM64_4K_PAGES) +#define ARM64_MEMSTART_SHIFT PUD_SHIFT +#elif defined(CONFIG_ARM64_16K_PAGES) +#define ARM64_MEMSTART_SHIFT CONT_PMD_SHIFT +#else +#define ARM64_MEMSTART_SHIFT PMD_SHIFT +#endif + +/* + * sparsemem vmemmap imposes an additional requirement on the alignment of + * memstart_addr, due to the fact that the base of the vmemmap region + * has a direct correspondence, and needs to appear sufficiently aligned + * in the virtual address space. + */ +#if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS +#define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS) +#else +#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT) +#endif + +#endif /* __ASM_KERNEL_PGTABLE_H */ |