Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Kernel page table mapping
3 *
4 * Copyright (C) 2015 ARM Ltd.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 */
18
19#ifndef __ASM_KERNEL_PGTABLE_H
20#define __ASM_KERNEL_PGTABLE_H
21
22#include <asm/pgtable.h>
23#include <asm/sparsemem.h>
24
25/*
26 * The linear mapping and the start of memory are both 2M aligned (per
27 * the arm64 booting.txt requirements). Hence we can use section mapping
28 * with 4K (section size = 2M) but not with 16K (section size = 32M) or
29 * 64K (section size = 512M).
30 */
31#ifdef CONFIG_ARM64_4K_PAGES
32#define ARM64_SWAPPER_USES_SECTION_MAPS 1
33#else
34#define ARM64_SWAPPER_USES_SECTION_MAPS 0
35#endif
36
37/*
38 * The idmap and swapper page tables need some space reserved in the kernel
39 * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
40 * map the kernel. With the 64K page configuration, swapper and idmap need to
41 * map to pte level. The swapper also maps the FDT (see __create_page_tables
42 * for more information). Note that the number of ID map translation levels
43 * could be increased on the fly if system RAM is out of reach for the default
44 * VA range, so pages required to map highest possible PA are reserved in all
45 * cases.
46 */
47#if ARM64_SWAPPER_USES_SECTION_MAPS
48#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
49#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT) - 1)
50#else
51#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
52#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
53#endif
54
55
56/*
57 * If KASLR is enabled, then an offset K is added to the kernel address
58 * space. The bottom 21 bits of this offset are zero to guarantee 2MB
59 * alignment for PA and VA.
60 *
61 * For each pagetable level of the swapper, we know that the shift will
62 * be larger than 21 (for the 4KB granule case we use section maps thus
63 * the smallest shift is actually 30) thus there is the possibility that
64 * KASLR can increase the number of pagetable entries by 1, so we make
65 * room for this extra entry.
66 *
67 * Note KASLR cannot increase the number of required entries for a level
68 * by more than one because it increments both the virtual start and end
69 * addresses equally (the extra entry comes from the case where the end
70 * address is just pushed over a boundary and the start address isn't).
71 */
72
73#ifdef CONFIG_RANDOMIZE_BASE
74#define EARLY_KASLR (1)
75#else
76#define EARLY_KASLR (0)
77#endif
78
79#define EARLY_ENTRIES(vstart, vend, shift) (((vend) >> (shift)) \
80 - ((vstart) >> (shift)) + 1 + EARLY_KASLR)
81
82#define EARLY_PGDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PGDIR_SHIFT))
83
84#if SWAPPER_PGTABLE_LEVELS > 3
85#define EARLY_PUDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, PUD_SHIFT))
86#else
87#define EARLY_PUDS(vstart, vend) (0)
88#endif
89
90#if SWAPPER_PGTABLE_LEVELS > 2
91#define EARLY_PMDS(vstart, vend) (EARLY_ENTRIES(vstart, vend, SWAPPER_TABLE_SHIFT))
92#else
93#define EARLY_PMDS(vstart, vend) (0)
94#endif
95
96#define EARLY_PAGES(vstart, vend) ( 1 /* PGDIR page */ \
97 + EARLY_PGDS((vstart), (vend)) /* each PGDIR needs a next level page table */ \
98 + EARLY_PUDS((vstart), (vend)) /* each PUD needs a next level page table */ \
99 + EARLY_PMDS((vstart), (vend))) /* each PMD needs a next level page table */
100#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR + TEXT_OFFSET, _end))
101#define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
102
103#ifdef CONFIG_ARM64_SW_TTBR0_PAN
104#define RESERVED_TTBR0_SIZE (PAGE_SIZE)
105#else
106#define RESERVED_TTBR0_SIZE (0)
107#endif
108
109/* Initial memory map size */
110#if ARM64_SWAPPER_USES_SECTION_MAPS
111#define SWAPPER_BLOCK_SHIFT SECTION_SHIFT
112#define SWAPPER_BLOCK_SIZE SECTION_SIZE
113#define SWAPPER_TABLE_SHIFT PUD_SHIFT
114#else
115#define SWAPPER_BLOCK_SHIFT PAGE_SHIFT
116#define SWAPPER_BLOCK_SIZE PAGE_SIZE
117#define SWAPPER_TABLE_SHIFT PMD_SHIFT
118#endif
119
120/* The size of the initial kernel direct mapping */
121#define SWAPPER_INIT_MAP_SIZE (_AC(1, UL) << SWAPPER_TABLE_SHIFT)
122
123/*
124 * Initial memory map attributes.
125 */
126#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
127#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
128
129#if ARM64_SWAPPER_USES_SECTION_MAPS
130#define SWAPPER_MM_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
131#else
132#define SWAPPER_MM_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
133#endif
134
135/*
136 * To make optimal use of block mappings when laying out the linear
137 * mapping, round down the base of physical memory to a size that can
138 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
139 * (64k granule), or a multiple that can be mapped using contiguous bits
140 * in the page tables: 32 * PMD_SIZE (16k granule)
141 */
142#if defined(CONFIG_ARM64_4K_PAGES)
143#define ARM64_MEMSTART_SHIFT PUD_SHIFT
144#elif defined(CONFIG_ARM64_16K_PAGES)
145#define ARM64_MEMSTART_SHIFT (PMD_SHIFT + 5)
146#else
147#define ARM64_MEMSTART_SHIFT PMD_SHIFT
148#endif
149
150/*
151 * sparsemem vmemmap imposes an additional requirement on the alignment of
152 * memstart_addr, due to the fact that the base of the vmemmap region
153 * has a direct correspondence, and needs to appear sufficiently aligned
154 * in the virtual address space.
155 */
156#if defined(CONFIG_SPARSEMEM_VMEMMAP) && ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
157#define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS)
158#else
159#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT)
160#endif
161
162#endif /* __ASM_KERNEL_PGTABLE_H */