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