arch/arm/include/asm/pgtable-3level.h

Source file repositories/reference/linux-study-clean/arch/arm/include/asm/pgtable-3level.h

File Facts

System
Linux kernel
Corpus path
arch/arm/include/asm/pgtable-3level.h
Extension
.h
Size
8133 bytes
Lines
251
Domain
Architecture Layer
Bucket
arch/arm
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _ASM_PGTABLE_3LEVEL_H
#define _ASM_PGTABLE_3LEVEL_H

/*
 * With LPAE, there are 3 levels of page tables. Each level has 512 entries of
 * 8 bytes each, occupying a 4K page. The first level table covers a range of
 * 512GB, each entry representing 1GB. Since we are limited to 4GB input
 * address range, only 4 entries in the PGD are used.
 *
 * There are enough spare bits in a page table entry for the kernel specific
 * state.
 */
#define PTRS_PER_PTE		512
#define PTRS_PER_PMD		512
#define PTRS_PER_PGD		4

#define PTE_HWTABLE_PTRS	(0)
#define PTE_HWTABLE_OFF		(0)
#define PTE_HWTABLE_SIZE	(PTRS_PER_PTE * sizeof(u64))

#define MAX_POSSIBLE_PHYSMEM_BITS 40

/*
 * PGDIR_SHIFT determines the size a top-level page table entry can map.
 */
#define PGDIR_SHIFT		30

/*
 * PMD_SHIFT determines the size a middle-level page table entry can map.
 */
#define PMD_SHIFT		21

#define PMD_SIZE		(1UL << PMD_SHIFT)
#define PMD_MASK		(~((1 << PMD_SHIFT) - 1))
#define PGDIR_SIZE		(1UL << PGDIR_SHIFT)
#define PGDIR_MASK		(~((1 << PGDIR_SHIFT) - 1))

/*
 * section address mask and size definitions.
 */
#define SECTION_SHIFT		21
#define SECTION_SIZE		(1UL << SECTION_SHIFT)
#define SECTION_MASK		(~((1 << SECTION_SHIFT) - 1))

#define USER_PTRS_PER_PGD	(PAGE_OFFSET / PGDIR_SIZE)

/*
 * Hugetlb definitions.
 */
#define HPAGE_SHIFT		PMD_SHIFT
#define HPAGE_SIZE		(_AC(1, UL) << HPAGE_SHIFT)
#define HPAGE_MASK		(~(HPAGE_SIZE - 1))
#define HUGETLB_PAGE_ORDER	(HPAGE_SHIFT - PAGE_SHIFT)

/*
 * "Linux" PTE definitions for LPAE.
 *
 * These bits overlap with the hardware bits but the naming is preserved for
 * consistency with the classic page table format.
 */
#define L_PTE_VALID		(_AT(pteval_t, 1) << 0)		/* Valid */
#define L_PTE_PRESENT		(_AT(pteval_t, 3) << 0)		/* Present */
#define L_PTE_USER		(_AT(pteval_t, 1) << 6)		/* AP[1] */
#define L_PTE_SHARED		(_AT(pteval_t, 3) << 8)		/* SH[1:0], inner shareable */
#define L_PTE_YOUNG		(_AT(pteval_t, 1) << 10)	/* AF */
#define L_PTE_XN		(_AT(pteval_t, 1) << 54)	/* XN */
#define L_PTE_DIRTY		(_AT(pteval_t, 1) << 55)
#define L_PTE_SPECIAL		(_AT(pteval_t, 1) << 56)
#define L_PTE_NONE		(_AT(pteval_t, 1) << 57)	/* PROT_NONE */
#define L_PTE_RDONLY		(_AT(pteval_t, 1) << 58)	/* READ ONLY */

/* We borrow bit 7 to store the exclusive marker in swap PTEs. */
#define L_PTE_SWP_EXCLUSIVE	(_AT(pteval_t, 1) << 7)

#define L_PMD_SECT_VALID	(_AT(pmdval_t, 1) << 0)
#define L_PMD_SECT_DIRTY	(_AT(pmdval_t, 1) << 55)
#define L_PMD_SECT_NONE		(_AT(pmdval_t, 1) << 57)
#define L_PMD_SECT_RDONLY	(_AT(pteval_t, 1) << 58)

/*
 * To be used in assembly code with the upper page attributes.
 */
#define L_PTE_XN_HIGH		(1 << (54 - 32))
#define L_PTE_DIRTY_HIGH	(1 << (55 - 32))

/*
 * AttrIndx[2:0] encoding (mapping attributes defined in the MAIR* registers).
 */
#define L_PTE_MT_UNCACHED	(_AT(pteval_t, 0) << 2)	/* strongly ordered */
#define L_PTE_MT_BUFFERABLE	(_AT(pteval_t, 1) << 2)	/* normal non-cacheable */

Annotation

Implementation Notes