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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#ifdef CONFIG_ARM64_4K_PAGES
22#define ARM64_KERNEL_USES_PMD_MAPS 1
23#else
24#define ARM64_KERNEL_USES_PMD_MAPS 0
25#endif
26
27/*
28 * The idmap and swapper page tables need some space reserved in the kernel
29 * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
30 * map the kernel. With the 64K page configuration, swapper and idmap need to
31 * map to pte level. The swapper also maps the FDT (see __create_page_tables
32 * for more information). Note that the number of ID map translation levels
33 * could be increased on the fly if system RAM is out of reach for the default
34 * VA range, so pages required to map highest possible PA are reserved in all
35 * cases.
36 */
37#if ARM64_KERNEL_USES_PMD_MAPS
38#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
39#else
40#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
41#endif
42
43
44/*
45 * If KASLR is enabled, then an offset K is added to the kernel address
46 * space. The bottom 21 bits of this offset are zero to guarantee 2MB
47 * alignment for PA and VA.
48 *
49 * For each pagetable level of the swapper, we know that the shift will
50 * be larger than 21 (for the 4KB granule case we use section maps thus
51 * the smallest shift is actually 30) thus there is the possibility that
52 * KASLR can increase the number of pagetable entries by 1, so we make
53 * room for this extra entry.
54 *
55 * Note KASLR cannot increase the number of required entries for a level
56 * by more than one because it increments both the virtual start and end
57 * addresses equally (the extra entry comes from the case where the end
58 * address is just pushed over a boundary and the start address isn't).
59 */
60
61#ifdef CONFIG_RANDOMIZE_BASE
62#define EARLY_KASLR (1)
63#else
64#define EARLY_KASLR (0)
65#endif
66
67#define EARLY_ENTRIES(vstart, vend, shift, add) \
68 ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1 + add)
69
70#define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add))
71
72#if SWAPPER_PGTABLE_LEVELS > 3
73#define EARLY_PUDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT, add))
74#else
75#define EARLY_PUDS(vstart, vend, add) (0)
76#endif
77
78#if SWAPPER_PGTABLE_LEVELS > 2
79#define EARLY_PMDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT, add))
80#else
81#define EARLY_PMDS(vstart, vend, add) (0)
82#endif
83
84#define EARLY_PAGES(vstart, vend, add) ( 1 /* PGDIR page */ \
85 + EARLY_PGDS((vstart), (vend), add) /* each PGDIR needs a next level page table */ \
86 + EARLY_PUDS((vstart), (vend), add) /* each PUD needs a next level page table */ \
87 + EARLY_PMDS((vstart), (vend), add)) /* each PMD needs a next level page table */
88#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end, EARLY_KASLR))
89
90/* the initial ID map may need two extra pages if it needs to be extended */
91#if VA_BITS < 48
92#define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE)
93#else
94#define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE)
95#endif
96#define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE, 1)
97
98/* Initial memory map size */
99#if ARM64_KERNEL_USES_PMD_MAPS
100#define SWAPPER_BLOCK_SHIFT PMD_SHIFT
101#define SWAPPER_BLOCK_SIZE PMD_SIZE
102#define SWAPPER_TABLE_SHIFT PUD_SHIFT
103#else
104#define SWAPPER_BLOCK_SHIFT PAGE_SHIFT
105#define SWAPPER_BLOCK_SIZE PAGE_SIZE
106#define SWAPPER_TABLE_SHIFT PMD_SHIFT
107#endif
108
109/*
110 * Initial memory map attributes.
111 */
112#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
113#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
114
115#if ARM64_KERNEL_USES_PMD_MAPS
116#define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
117#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY)
118#else
119#define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
120#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
121#endif
122
123/*
124 * To make optimal use of block mappings when laying out the linear
125 * mapping, round down the base of physical memory to a size that can
126 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
127 * (64k granule), or a multiple that can be mapped using contiguous bits
128 * in the page tables: 32 * PMD_SIZE (16k granule)
129 */
130#if defined(CONFIG_ARM64_4K_PAGES)
131#define ARM64_MEMSTART_SHIFT PUD_SHIFT
132#elif defined(CONFIG_ARM64_16K_PAGES)
133#define ARM64_MEMSTART_SHIFT CONT_PMD_SHIFT
134#else
135#define ARM64_MEMSTART_SHIFT PMD_SHIFT
136#endif
137
138/*
139 * sparsemem vmemmap imposes an additional requirement on the alignment of
140 * memstart_addr, due to the fact that the base of the vmemmap region
141 * has a direct correspondence, and needs to appear sufficiently aligned
142 * in the virtual address space.
143 */
144#if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
145#define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS)
146#else
147#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT)
148#endif
149
150#endif /* __ASM_KERNEL_PGTABLE_H */