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_KERNEL_USES_PMD_MAPS 1
22 #else
23 #define ARM64_KERNEL_USES_PMD_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_KERNEL_USES_PMD_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, _end))
90 #define IDMAP_DIR_SIZE		(IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
91 
92 /* Initial memory map size */
93 #if ARM64_KERNEL_USES_PMD_MAPS
94 #define SWAPPER_BLOCK_SHIFT	PMD_SHIFT
95 #define SWAPPER_BLOCK_SIZE	PMD_SIZE
96 #define SWAPPER_TABLE_SHIFT	PUD_SHIFT
97 #else
98 #define SWAPPER_BLOCK_SHIFT	PAGE_SHIFT
99 #define SWAPPER_BLOCK_SIZE	PAGE_SIZE
100 #define SWAPPER_TABLE_SHIFT	PMD_SHIFT
101 #endif
102 
103 /*
104  * Initial memory map attributes.
105  */
106 #define SWAPPER_PTE_FLAGS	(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
107 #define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
108 
109 #if ARM64_KERNEL_USES_PMD_MAPS
110 #define SWAPPER_MM_MMUFLAGS	(PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
111 #else
112 #define SWAPPER_MM_MMUFLAGS	(PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
113 #endif
114 
115 /*
116  * To make optimal use of block mappings when laying out the linear
117  * mapping, round down the base of physical memory to a size that can
118  * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
119  * (64k granule), or a multiple that can be mapped using contiguous bits
120  * in the page tables: 32 * PMD_SIZE (16k granule)
121  */
122 #if defined(CONFIG_ARM64_4K_PAGES)
123 #define ARM64_MEMSTART_SHIFT		PUD_SHIFT
124 #elif defined(CONFIG_ARM64_16K_PAGES)
125 #define ARM64_MEMSTART_SHIFT		CONT_PMD_SHIFT
126 #else
127 #define ARM64_MEMSTART_SHIFT		PMD_SHIFT
128 #endif
129 
130 /*
131  * sparsemem vmemmap imposes an additional requirement on the alignment of
132  * memstart_addr, due to the fact that the base of the vmemmap region
133  * has a direct correspondence, and needs to appear sufficiently aligned
134  * in the virtual address space.
135  */
136 #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
137 #define ARM64_MEMSTART_ALIGN	(1UL << SECTION_SIZE_BITS)
138 #else
139 #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
140 #endif
141 
142 #endif	/* __ASM_KERNEL_PGTABLE_H */
143