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 SPAN_NR_ENTRIES(vstart, vend, shift) \
63	((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1)
64
65#define EARLY_ENTRIES(vstart, vend, shift, add) \
66	(SPAN_NR_ENTRIES(vstart, vend, shift) + (add))
67
68#define EARLY_PGDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT, add))
69
70#if SWAPPER_PGTABLE_LEVELS > 3
71#define EARLY_PUDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT, add))
72#else
73#define EARLY_PUDS(vstart, vend, add) (0)
74#endif
75
76#if SWAPPER_PGTABLE_LEVELS > 2
77#define EARLY_PMDS(vstart, vend, add) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT, add))
78#else
79#define EARLY_PMDS(vstart, vend, add) (0)
80#endif
81
82#define EARLY_PAGES(vstart, vend, add) ( 1 			/* PGDIR page */				\
83			+ EARLY_PGDS((vstart), (vend), add) 	/* each PGDIR needs a next level page table */	\
84			+ EARLY_PUDS((vstart), (vend), add)	/* each PUD needs a next level page table */	\
85			+ EARLY_PMDS((vstart), (vend), add))	/* each PMD needs a next level page table */
86#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end, EARLY_KASLR))
87
88/* the initial ID map may need two extra pages if it needs to be extended */
89#if VA_BITS < 48
90#define INIT_IDMAP_DIR_SIZE	((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE)
91#else
92#define INIT_IDMAP_DIR_SIZE	(INIT_IDMAP_DIR_PAGES * PAGE_SIZE)
93#endif
94#define INIT_IDMAP_DIR_PAGES	EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE, 1)
95
96/* Initial memory map size */
97#ifdef CONFIG_ARM64_4K_PAGES
98#define SWAPPER_BLOCK_SHIFT	PMD_SHIFT
99#define SWAPPER_BLOCK_SIZE	PMD_SIZE
100#define SWAPPER_TABLE_SHIFT	PUD_SHIFT
101#else
102#define SWAPPER_BLOCK_SHIFT	PAGE_SHIFT
103#define SWAPPER_BLOCK_SIZE	PAGE_SIZE
104#define SWAPPER_TABLE_SHIFT	PMD_SHIFT
105#endif
106
107/*
108 * Initial memory map attributes.
109 */
110#define SWAPPER_PTE_FLAGS	(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED | PTE_UXN)
111#define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PTE_UXN)
112
113#ifdef CONFIG_ARM64_4K_PAGES
114#define SWAPPER_RW_MMUFLAGS	(PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS | PTE_WRITE)
115#define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY)
116#else
117#define SWAPPER_RW_MMUFLAGS	(PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS | PTE_WRITE)
118#define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
119#endif
120
121#endif	/* __ASM_KERNEL_PGTABLE_H */
122