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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Kernel page table mapping
4 *
5 * Copyright (C) 2015 ARM Ltd.
6 */
7
8#ifndef __ASM_KERNEL_PGTABLE_H
9#define __ASM_KERNEL_PGTABLE_H
10
11#include <asm/boot.h>
12#include <asm/pgtable-hwdef.h>
13#include <asm/sparsemem.h>
14
15/*
16 * The linear mapping and the start of memory are both 2M aligned (per
17 * the arm64 booting.txt requirements). Hence we can use section mapping
18 * with 4K (section size = 2M) but not with 16K (section size = 32M) or
19 * 64K (section size = 512M).
20 */
21
22/*
23 * The idmap and swapper page tables need some space reserved in the kernel
24 * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
25 * map the kernel. With the 64K page configuration, swapper and idmap need to
26 * map to pte level. The swapper also maps the FDT (see __create_page_tables
27 * for more information). Note that the number of ID map translation levels
28 * could be increased on the fly if system RAM is out of reach for the default
29 * VA range, so pages required to map highest possible PA are reserved in all
30 * cases.
31 */
32#ifdef CONFIG_ARM64_4K_PAGES
33#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
34#else
35#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
36#endif
37
38
39/*
40 * If KASLR is enabled, then an offset K is added to the kernel address
41 * space. The bottom 21 bits of this offset are zero to guarantee 2MB
42 * alignment for PA and VA.
43 *
44 * For each pagetable level of the swapper, we know that the shift will
45 * be larger than 21 (for the 4KB granule case we use section maps thus
46 * the smallest shift is actually 30) thus there is the possibility that
47 * KASLR can increase the number of pagetable entries by 1, so we make
48 * room for this extra entry.
49 *
50 * Note KASLR cannot increase the number of required entries for a level
51 * by more than one because it increments both the virtual start and end
52 * addresses equally (the extra entry comes from the case where the end
53 * address is just pushed over a boundary and the start address isn't).
54 */
55
56#ifdef CONFIG_RANDOMIZE_BASE
57#define EARLY_KASLR (1)
58#else
59#define EARLY_KASLR (0)
60#endif
61
62#define EARLY_ENTRIES(vstart, vend, shift, add) \
63 ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1 + add)
64
65#define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add))
66
67#if SWAPPER_PGTABLE_LEVELS > 3
68#define EARLY_PUDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT, add))
69#else
70#define EARLY_PUDS(vstart, vend, add) (0)
71#endif
72
73#if SWAPPER_PGTABLE_LEVELS > 2
74#define EARLY_PMDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT, add))
75#else
76#define EARLY_PMDS(vstart, vend, add) (0)
77#endif
78
79#define EARLY_PAGES(vstart, vend, add) ( 1 /* PGDIR page */ \
80 + EARLY_PGDS((vstart), (vend), add) /* each PGDIR needs a next level page table */ \
81 + EARLY_PUDS((vstart), (vend), add) /* each PUD needs a next level page table */ \
82 + EARLY_PMDS((vstart), (vend), add)) /* each PMD needs a next level page table */
83#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end, EARLY_KASLR))
84
85/* the initial ID map may need two extra pages if it needs to be extended */
86#if VA_BITS < 48
87#define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE)
88#else
89#define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE)
90#endif
91#define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE, 1)
92
93/* Initial memory map size */
94#ifdef CONFIG_ARM64_4K_PAGES
95#define SWAPPER_BLOCK_SHIFT PMD_SHIFT
96#define SWAPPER_BLOCK_SIZE PMD_SIZE
97#define SWAPPER_TABLE_SHIFT PUD_SHIFT
98#else
99#define SWAPPER_BLOCK_SHIFT PAGE_SHIFT
100#define SWAPPER_BLOCK_SIZE PAGE_SIZE
101#define SWAPPER_TABLE_SHIFT PMD_SHIFT
102#endif
103
104/*
105 * Initial memory map attributes.
106 */
107#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
108#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
109
110#ifdef CONFIG_ARM64_4K_PAGES
111#define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
112#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY)
113#else
114#define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
115#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
116#endif
117
118/*
119 * To make optimal use of block mappings when laying out the linear
120 * mapping, round down the base of physical memory to a size that can
121 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
122 * (64k granule), or a multiple that can be mapped using contiguous bits
123 * in the page tables: 32 * PMD_SIZE (16k granule)
124 */
125#if defined(CONFIG_ARM64_4K_PAGES)
126#define ARM64_MEMSTART_SHIFT PUD_SHIFT
127#elif defined(CONFIG_ARM64_16K_PAGES)
128#define ARM64_MEMSTART_SHIFT CONT_PMD_SHIFT
129#else
130#define ARM64_MEMSTART_SHIFT PMD_SHIFT
131#endif
132
133/*
134 * sparsemem vmemmap imposes an additional requirement on the alignment of
135 * memstart_addr, due to the fact that the base of the vmemmap region
136 * has a direct correspondence, and needs to appear sufficiently aligned
137 * in the virtual address space.
138 */
139#if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
140#define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS)
141#else
142#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT)
143#endif
144
145#endif /* __ASM_KERNEL_PGTABLE_H */