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kernel-pgtable.h
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kernel-pgtable.h
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/* 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/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_SWAPPER_USES_SECTION_MAPS 1
#else
#define ARM64_SWAPPER_USES_SECTION_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_SWAPPER_USES_SECTION_MAPS
#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT) - 1)
#else
#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
#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) (((vend) >> (shift)) \
- ((vstart) >> (shift)) + 1 + EARLY_KASLR)
#define EARLY_PGDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT))
#if SWAPPER_PGTABLE_LEVELS > 3
#define EARLY_PUDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT))
#else
#define EARLY_PUDS(vstart, vend) (0)
#endif
#if SWAPPER_PGTABLE_LEVELS > 2
#define EARLY_PMDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT))
#else
#define EARLY_PMDS(vstart, vend) (0)
#endif
#define EARLY_PAGES(vstart, vend) ( 1 /* PGDIR page */ \
+ EARLY_PGDS((vstart), (vend)) /* each PGDIR needs a next level page table */ \
+ EARLY_PUDS((vstart), (vend)) /* each PUD needs a next level page table */ \
+ EARLY_PMDS((vstart), (vend))) /* each PMD needs a next level page table */
#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR + TEXT_OFFSET, _end))
#define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
#define RESERVED_TTBR0_SIZE (PAGE_SIZE)
#else
#define RESERVED_TTBR0_SIZE (0)
#endif
/* Initial memory map size */
#if ARM64_SWAPPER_USES_SECTION_MAPS
#define SWAPPER_BLOCK_SHIFT SECTION_SHIFT
#define SWAPPER_BLOCK_SIZE SECTION_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
/* The size of the initial kernel direct mapping */
#define SWAPPER_INIT_MAP_SIZE (_AC(1, UL) << SWAPPER_TABLE_SHIFT)
/*
* 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_SWAPPER_USES_SECTION_MAPS
#define SWAPPER_MM_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
#else
#define SWAPPER_MM_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
#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 (PMD_SHIFT + 5)
#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 defined(CONFIG_SPARSEMEM_VMEMMAP) && 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 */