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+/*
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+ * This file is subject to the terms and conditions of the GNU General Public
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+ * License. See the file "COPYING" in the main directory of this archive
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+ * for more details.
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+ *
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+ * Copyright (C) 1994, 95, 96, 97, 98, 99, 2000, 2003 Ralf Baechle
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+ * Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
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+ */
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+#ifndef _ASM_PGTABLE_64_H
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+#define _ASM_PGTABLE_64_H
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+
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+#include <linux/compiler.h>
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+#include <linux/linkage.h>
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+
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+#include <asm/addrspace.h>
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+#include <asm/page.h>
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+#include <asm/cachectl.h>
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+#include <asm/fixmap.h>
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+
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+#ifdef CONFIG_PAGE_SIZE_64KB
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+#include <asm-generic/pgtable-nopmd.h>
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+#else
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+#include <asm-generic/pgtable-nopud.h>
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+#endif
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+
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+/*
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+ * Each address space has 2 4K pages as its page directory, giving 1024
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+ * (== PTRS_PER_PGD) 8 byte pointers to pmd tables. Each pmd table is a
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+ * single 4K page, giving 512 (== PTRS_PER_PMD) 8 byte pointers to page
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+ * tables. Each page table is also a single 4K page, giving 512 (==
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+ * PTRS_PER_PTE) 8 byte ptes. Each pud entry is initialized to point to
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+ * invalid_pmd_table, each pmd entry is initialized to point to
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+ * invalid_pte_table, each pte is initialized to 0. When memory is low,
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+ * and a pmd table or a page table allocation fails, empty_bad_pmd_table
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+ * and empty_bad_page_table is returned back to higher layer code, so
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+ * that the failure is recognized later on. Linux does not seem to
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+ * handle these failures very well though. The empty_bad_page_table has
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+ * invalid pte entries in it, to force page faults.
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+ *
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+ * Kernel mappings: kernel mappings are held in the swapper_pg_table.
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+ * The layout is identical to userspace except it's indexed with the
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+ * fault address - VMALLOC_START.
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+ */
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+
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+
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+/* PGDIR_SHIFT determines what a third-level page table entry can map */
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+#ifdef __PAGETABLE_PMD_FOLDED
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+#define PGDIR_SHIFT (PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3)
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+#else
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+
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+/* PMD_SHIFT determines the size of the area a second-level page table can map */
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+#define PMD_SHIFT (PAGE_SHIFT + (PAGE_SHIFT + PTE_ORDER - 3))
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+#define PMD_SIZE (1UL << PMD_SHIFT)
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+#define PMD_MASK (~(PMD_SIZE-1))
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+
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+
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+#define PGDIR_SHIFT (PMD_SHIFT + (PAGE_SHIFT + PMD_ORDER - 3))
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+#endif
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+#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
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+#define PGDIR_MASK (~(PGDIR_SIZE-1))
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+
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+/*
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+ * For 4kB page size we use a 3 level page tree and an 8kB pud, which
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+ * permits us mapping 40 bits of virtual address space.
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+ *
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+ * We used to implement 41 bits by having an order 1 pmd level but that seemed
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+ * rather pointless.
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+ *
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+ * For 8kB page size we use a 3 level page tree which permits a total of
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+ * 8TB of address space. Alternatively a 33-bit / 8GB organization using
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+ * two levels would be easy to implement.
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+ *
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+ * For 16kB page size we use a 2 level page tree which permits a total of
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+ * 36 bits of virtual address space. We could add a third level but it seems
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+ * like at the moment there's no need for this.
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+ *
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+ * For 64kB page size we use a 2 level page table tree for a total of 42 bits
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+ * of virtual address space.
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+ */
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+#ifdef CONFIG_PAGE_SIZE_4KB
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+#define PGD_ORDER 1
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+#define PUD_ORDER aieeee_attempt_to_allocate_pud
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+#define PMD_ORDER 0
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+#define PTE_ORDER 0
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+#endif
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+#ifdef CONFIG_PAGE_SIZE_8KB
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+#define PGD_ORDER 0
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+#define PUD_ORDER aieeee_attempt_to_allocate_pud
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+#define PMD_ORDER 0
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+#define PTE_ORDER 0
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+#endif
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+#ifdef CONFIG_PAGE_SIZE_16KB
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+#define PGD_ORDER 0
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+#define PUD_ORDER aieeee_attempt_to_allocate_pud
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+#define PMD_ORDER 0
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+#define PTE_ORDER 0
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+#endif
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+#ifdef CONFIG_PAGE_SIZE_32KB
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+#define PGD_ORDER 0
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+#define PUD_ORDER aieeee_attempt_to_allocate_pud
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+#define PMD_ORDER 0
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+#define PTE_ORDER 0
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+#endif
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+#ifdef CONFIG_PAGE_SIZE_64KB
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+#define PGD_ORDER 0
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+#define PUD_ORDER aieeee_attempt_to_allocate_pud
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+#define PMD_ORDER aieeee_attempt_to_allocate_pmd
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+#define PTE_ORDER 0
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+#endif
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+
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+#define PTRS_PER_PGD ((PAGE_SIZE << PGD_ORDER) / sizeof(pgd_t))
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+#ifndef __PAGETABLE_PMD_FOLDED
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+#define PTRS_PER_PMD ((PAGE_SIZE << PMD_ORDER) / sizeof(pmd_t))
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+#endif
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+#define PTRS_PER_PTE ((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))
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+
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+#if PGDIR_SIZE >= TASK_SIZE64
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+#define USER_PTRS_PER_PGD (1)
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+#else
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+#define USER_PTRS_PER_PGD (TASK_SIZE64 / PGDIR_SIZE)
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+#endif
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