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-rw-r--r--arch/arm64/include/asm/kernel-pgtable.h121
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diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/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/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
+
+
+/*
+ * 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 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, EARLY_KASLR))
+
+/* 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 */