arch/arm64/include/asm/kernel-pgtable.h

/* 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).
 */

/*
 * 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.
 */
#ifdef CONFIG_ARM64_4K_PAGES
#define SWAPPER_PGTABLE_LEVELS	(CONFIG_PGTABLE_LEVELS - 1)
#else
#define SWAPPER_PGTABLE_LEVELS	(CONFIG_PGTABLE_LEVELS)
#endif


/*
 * A relocatable kernel may execute from an address that differs from the one at
 * which it was linked. In the worst case, its runtime placement may intersect
 * with two adjacent PGDIR entries, which means that an additional page table
 * may be needed at each subordinate level.
 */
#define EXTRA_PAGE	__is_defined(CONFIG_RELOCATABLE)

#define SPAN_NR_ENTRIES(vstart, vend, shift) \
	((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1)

#define EARLY_ENTRIES(vstart, vend, shift, add) \
	(SPAN_NR_ENTRIES(vstart, vend, shift) + (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, EXTRA_PAGE))

/* 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 */
#ifdef CONFIG_ARM64_4K_PAGES
#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 | PTE_UXN)
#define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PTE_UXN)

#ifdef CONFIG_ARM64_4K_PAGES
#define SWAPPER_RW_MMUFLAGS	(PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS | PTE_WRITE)
#define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY)
#else
#define SWAPPER_RW_MMUFLAGS	(PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS | PTE_WRITE)
#define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
#endif

#endif	/* __ASM_KERNEL_PGTABLE_H */