1. 根目录:
2. arch
3. arm
4. include
5. asm
6. pgtable-3level.h

/*
 * arch/arm/include/asm/pgtable-3level.h
 *
 * Copyright (C) 2011 ARM Ltd.
 * Author: Catalin Marinas <catalin.marinas@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#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))

/*
 * 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_FILE		(_AT(pteval_t, 1) << 2)		/* only when !PRESENT */
#define L_PTE_USER		(_AT(pteval_t, 1) << 6)		/* AP[1] */
#define L_PTE_RDONLY		(_AT(pteval_t, 1) << 7)		/* AP[2] */
#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)	/* unused */
#define L_PTE_SPECIAL		(_AT(pteval_t, 1) << 56)	/* unused */
#define L_PTE_NONE		(_AT(pteval_t, 1) << 57)	/* PROT_NONE */

#define PMD_SECT_VALID		(_AT(pmdval_t, 1) << 0)
#define PMD_SECT_DIRTY		(_AT(pmdval_t, 1) << 55)
#define PMD_SECT_SPLITTING	(_AT(pmdval_t, 1) << 56)
#define PMD_SECT_NONE		(_AT(pmdval_t, 1) << 57)

/*
 * 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 */
#define L_PTE_MT_WRITETHROUGH	(_AT(pteval_t, 2) << 2)	/* normal inner write-through */
#define L_PTE_MT_WRITEBACK	(_AT(pteval_t, 3) << 2)	/* normal inner write-back */
#define L_PTE_MT_WRITEALLOC	(_AT(pteval_t, 7) << 2)	/* normal inner write-alloc */
#define L_PTE_MT_DEV_SHARED	(_AT(pteval_t, 4) << 2)	/* device */
#define L_PTE_MT_DEV_NONSHARED	(_AT(pteval_t, 4) << 2)	/* device */
#define L_PTE_MT_DEV_WC		(_AT(pteval_t, 1) << 2)	/* normal non-cacheable */
#define L_PTE_MT_DEV_CACHED	(_AT(pteval_t, 3) << 2)	/* normal inner write-back */
#define L_PTE_MT_MASK		(_AT(pteval_t, 7) << 2)

/*
 * Software PGD flags.
 */
#define L_PGD_SWAPPER		(_AT(pgdval_t, 1) << 55)	/* swapper_pg_dir entry */

/*
 * 2nd stage PTE definitions for LPAE.
 */
#define L_PTE_S2_MT_UNCACHED		(_AT(pteval_t, 0x0) << 2) /* strongly ordered */
#define L_PTE_S2_MT_WRITETHROUGH	(_AT(pteval_t, 0xa) << 2) /* normal inner write-through */
#define L_PTE_S2_MT_WRITEBACK		(_AT(pteval_t, 0xf) << 2) /* normal inner write-back */
#define L_PTE_S2_MT_DEV_SHARED		(_AT(pteval_t, 0x1) << 2) /* device */
#define L_PTE_S2_MT_MASK		(_AT(pteval_t, 0xf) << 2)

#define L_PTE_S2_RDONLY			(_AT(pteval_t, 1) << 6)   /* HAP[1]   */
#define L_PTE_S2_RDWR			(_AT(pteval_t, 3) << 6)   /* HAP[2:1] */

#define L_PMD_S2_RDWR			(_AT(pmdval_t, 3) << 6)   /* HAP[2:1] */

/*
 * Hyp-mode PL2 PTE definitions for LPAE.
 */
#define L_PTE_HYP		L_PTE_USER

#ifndef __ASSEMBLY__

#define pud_none(pud)		(!pud_val(pud))
#define pud_bad(pud)		(!(pud_val(pud) & 2))
#define pud_present(pud)	(pud_val(pud))
#define pmd_table(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
						 PMD_TYPE_TABLE)
#define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
						 PMD_TYPE_SECT)
#define pmd_large(pmd)		pmd_sect(pmd)

#define pud_clear(pudp)			\
	do {				\
		*pudp = __pud(0);	\
		clean_pmd_entry(pudp);	\
	} while (0)

#define set_pud(pudp, pud)		\
	do {				\
		*pudp = pud;		\
		flush_pmd_entry(pudp);	\
	} while (0)

static inline pmd_t *pud_page_vaddr(pud_t pud)
{
	return __va(pud_val(pud) & PHYS_MASK & (s32)PAGE_MASK);
}

/* Find an entry in the second-level page table.. */
#define pmd_index(addr)		(((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
{
	return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr);
}

#define pmd_bad(pmd)		(!(pmd_val(pmd) & 2))

#define copy_pmd(pmdpd,pmdps)		\
	do {				\
		*pmdpd = *pmdps;	\
		flush_pmd_entry(pmdpd);	\
	} while (0)

#define pmd_clear(pmdp)			\
	do {				\
		*pmdp = __pmd(0);	\
		clean_pmd_entry(pmdp);	\
	} while (0)

/*
 * For 3 levels of paging the PTE_EXT_NG bit will be set for user address ptes
 * that are written to a page table but not for ptes created with mk_pte.
 *
 * In hugetlb_no_page, a new huge pte (new_pte) is generated and passed to
 * hugetlb_cow, where it is compared with an entry in a page table.
 * This comparison test fails erroneously leading ultimately to a memory leak.
 *
 * To correct this behaviour, we mask off PTE_EXT_NG for any pte that is
 * present before running the comparison.
 */
#define __HAVE_ARCH_PTE_SAME
#define pte_same(pte_a,pte_b)	((pte_present(pte_a) ? pte_val(pte_a) & ~PTE_EXT_NG	\
					: pte_val(pte_a))				\
				== (pte_present(pte_b) ? pte_val(pte_b) & ~PTE_EXT_NG	\
					: pte_val(pte_b)))

#define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,__pte(pte_val(pte)|(ext)))

#define pte_huge(pte)		(pte_val(pte) && !(pte_val(pte) & PTE_TABLE_BIT))
#define pte_mkhuge(pte)		(__pte(pte_val(pte) & ~PTE_TABLE_BIT))

#define pmd_young(pmd)		(pmd_val(pmd) & PMD_SECT_AF)

#define __HAVE_ARCH_PMD_WRITE
#define pmd_write(pmd)		(!(pmd_val(pmd) & PMD_SECT_RDONLY))

#define pmd_hugewillfault(pmd)	(!pmd_young(pmd) || !pmd_write(pmd))
#define pmd_thp_or_huge(pmd)	(pmd_huge(pmd) || pmd_trans_huge(pmd))

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_trans_huge(pmd)	(pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
#define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_SECT_SPLITTING)
#endif

#define PMD_BIT_FUNC(fn,op) \
static inline pmd_t pmd_##fn(pmd_t pmd) { pmd_val(pmd) op; return pmd; }

PMD_BIT_FUNC(wrprotect,	|= PMD_SECT_RDONLY);
PMD_BIT_FUNC(mkold,	&= ~PMD_SECT_AF);
PMD_BIT_FUNC(mksplitting, |= PMD_SECT_SPLITTING);
PMD_BIT_FUNC(mkwrite,   &= ~PMD_SECT_RDONLY);
PMD_BIT_FUNC(mkdirty,   |= PMD_SECT_DIRTY);
PMD_BIT_FUNC(mkyoung,   |= PMD_SECT_AF);

#define pmd_mkhuge(pmd)		(__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT))

#define pmd_pfn(pmd)		(((pmd_val(pmd) & PMD_MASK) & PHYS_MASK) >> PAGE_SHIFT)
#define pfn_pmd(pfn,prot)	(__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
#define mk_pmd(page,prot)	pfn_pmd(page_to_pfn(page),prot)

/* represent a notpresent pmd by zero, this is used by pmdp_invalidate */
#define pmd_mknotpresent(pmd)	(__pmd(0))

static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
{
	const pmdval_t mask = PMD_SECT_USER | PMD_SECT_XN | PMD_SECT_RDONLY |
				PMD_SECT_VALID | PMD_SECT_NONE;
	pmd_val(pmd) = (pmd_val(pmd) & ~mask) | (pgprot_val(newprot) & mask);
	return pmd;
}

static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
			      pmd_t *pmdp, pmd_t pmd)
{
	BUG_ON(addr >= TASK_SIZE);

	/* create a faulting entry if PROT_NONE protected */
	if (pmd_val(pmd) & PMD_SECT_NONE)
		pmd_val(pmd) &= ~PMD_SECT_VALID;

	*pmdp = __pmd(pmd_val(pmd) | PMD_SECT_nG);
	flush_pmd_entry(pmdp);
}

static inline int has_transparent_hugepage(void)
{
	return 1;
}

#endif /* __ASSEMBLY__ */

#endif /* _ASM_PGTABLE_3LEVEL_H */