Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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/pgtable-hwdef.h>
12#include <asm/sparsemem.h>
13
14/*
15 * The linear mapping and the start of memory are both 2M aligned (per
16 * the arm64 booting.txt requirements). Hence we can use section mapping
17 * with 4K (section size = 2M) but not with 16K (section size = 32M) or
18 * 64K (section size = 512M).
19 */
20#ifdef CONFIG_ARM64_4K_PAGES
21#define ARM64_SWAPPER_USES_SECTION_MAPS 1
22#else
23#define ARM64_SWAPPER_USES_SECTION_MAPS 0
24#endif
25
26/*
27 * The idmap and swapper page tables need some space reserved in the kernel
28 * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
29 * map the kernel. With the 64K page configuration, swapper and idmap need to
30 * map to pte level. The swapper also maps the FDT (see __create_page_tables
31 * for more information). Note that the number of ID map translation levels
32 * could be increased on the fly if system RAM is out of reach for the default
33 * VA range, so pages required to map highest possible PA are reserved in all
34 * cases.
35 */
36#if ARM64_SWAPPER_USES_SECTION_MAPS
37#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
38#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT) - 1)
39#else
40#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
41#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
42#endif
43
44
45/*
46 * If KASLR is enabled, then an offset K is added to the kernel address
47 * space. The bottom 21 bits of this offset are zero to guarantee 2MB
48 * alignment for PA and VA.
49 *
50 * For each pagetable level of the swapper, we know that the shift will
51 * be larger than 21 (for the 4KB granule case we use section maps thus
52 * the smallest shift is actually 30) thus there is the possibility that
53 * KASLR can increase the number of pagetable entries by 1, so we make
54 * room for this extra entry.
55 *
56 * Note KASLR cannot increase the number of required entries for a level
57 * by more than one because it increments both the virtual start and end
58 * addresses equally (the extra entry comes from the case where the end
59 * address is just pushed over a boundary and the start address isn't).
60 */
61
62#ifdef CONFIG_RANDOMIZE_BASE
63#define EARLY_KASLR (1)
64#else
65#define EARLY_KASLR (0)
66#endif
67
68#define EARLY_ENTRIES(vstart, vend, shift) (((vend) >> (shift)) \
69 - ((vstart) >> (shift)) + 1 + EARLY_KASLR)
70
71#define EARLY_PGDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT))
72
73#if SWAPPER_PGTABLE_LEVELS > 3
74#define EARLY_PUDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT))
75#else
76#define EARLY_PUDS(vstart, vend) (0)
77#endif
78
79#if SWAPPER_PGTABLE_LEVELS > 2
80#define EARLY_PMDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT))
81#else
82#define EARLY_PMDS(vstart, vend) (0)
83#endif
84
85#define EARLY_PAGES(vstart, vend) ( 1 /* PGDIR page */ \
86 + EARLY_PGDS((vstart), (vend)) /* each PGDIR needs a next level page table */ \
87 + EARLY_PUDS((vstart), (vend)) /* each PUD needs a next level page table */ \
88 + EARLY_PMDS((vstart), (vend))) /* each PMD needs a next level page table */
89#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR + TEXT_OFFSET, _end))
90#define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
91
92#ifdef CONFIG_ARM64_SW_TTBR0_PAN
93#define RESERVED_TTBR0_SIZE (PAGE_SIZE)
94#else
95#define RESERVED_TTBR0_SIZE (0)
96#endif
97
98/* Initial memory map size */
99#if ARM64_SWAPPER_USES_SECTION_MAPS
100#define SWAPPER_BLOCK_SHIFT SECTION_SHIFT
101#define SWAPPER_BLOCK_SIZE SECTION_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/* The size of the initial kernel direct mapping */
110#define SWAPPER_INIT_MAP_SIZE (_AC(1, UL) << SWAPPER_TABLE_SHIFT)
111
112/*
113 * Initial memory map attributes.
114 */
115#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
116#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
117
118#if ARM64_SWAPPER_USES_SECTION_MAPS
119#define SWAPPER_MM_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
120#else
121#define SWAPPER_MM_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
122#endif
123
124/*
125 * To make optimal use of block mappings when laying out the linear
126 * mapping, round down the base of physical memory to a size that can
127 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
128 * (64k granule), or a multiple that can be mapped using contiguous bits
129 * in the page tables: 32 * PMD_SIZE (16k granule)
130 */
131#if defined(CONFIG_ARM64_4K_PAGES)
132#define ARM64_MEMSTART_SHIFT PUD_SHIFT
133#elif defined(CONFIG_ARM64_16K_PAGES)
134#define ARM64_MEMSTART_SHIFT (PMD_SHIFT + 5)
135#else
136#define ARM64_MEMSTART_SHIFT PMD_SHIFT
137#endif
138
139/*
140 * sparsemem vmemmap imposes an additional requirement on the alignment of
141 * memstart_addr, due to the fact that the base of the vmemmap region
142 * has a direct correspondence, and needs to appear sufficiently aligned
143 * in the virtual address space.
144 */
145#if defined(CONFIG_SPARSEMEM_VMEMMAP) && ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
146#define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS)
147#else
148#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT)
149#endif
150
151#endif /* __ASM_KERNEL_PGTABLE_H */