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 #define SWAPPER_DIR_SIZE	(SWAPPER_PGTABLE_LEVELS * PAGE_SIZE)
56 #define IDMAP_DIR_SIZE		(IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
57 
58 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
59 #define RESERVED_TTBR0_SIZE	(PAGE_SIZE)
60 #else
61 #define RESERVED_TTBR0_SIZE	(0)
62 #endif
63 
64 /* Initial memory map size */
65 #if ARM64_SWAPPER_USES_SECTION_MAPS
66 #define SWAPPER_BLOCK_SHIFT	SECTION_SHIFT
67 #define SWAPPER_BLOCK_SIZE	SECTION_SIZE
68 #define SWAPPER_TABLE_SHIFT	PUD_SHIFT
69 #else
70 #define SWAPPER_BLOCK_SHIFT	PAGE_SHIFT
71 #define SWAPPER_BLOCK_SIZE	PAGE_SIZE
72 #define SWAPPER_TABLE_SHIFT	PMD_SHIFT
73 #endif
74 
75 /* The size of the initial kernel direct mapping */
76 #define SWAPPER_INIT_MAP_SIZE	(_AC(1, UL) << SWAPPER_TABLE_SHIFT)
77 
78 /*
79  * Initial memory map attributes.
80  */
81 #define SWAPPER_PTE_FLAGS	(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
82 #define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
83 
84 #if ARM64_SWAPPER_USES_SECTION_MAPS
85 #define SWAPPER_MM_MMUFLAGS	(PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
86 #else
87 #define SWAPPER_MM_MMUFLAGS	(PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
88 #endif
89 
90 /*
91  * To make optimal use of block mappings when laying out the linear
92  * mapping, round down the base of physical memory to a size that can
93  * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
94  * (64k granule), or a multiple that can be mapped using contiguous bits
95  * in the page tables: 32 * PMD_SIZE (16k granule)
96  */
97 #if defined(CONFIG_ARM64_4K_PAGES)
98 #define ARM64_MEMSTART_SHIFT		PUD_SHIFT
99 #elif defined(CONFIG_ARM64_16K_PAGES)
100 #define ARM64_MEMSTART_SHIFT		(PMD_SHIFT + 5)
101 #else
102 #define ARM64_MEMSTART_SHIFT		PMD_SHIFT
103 #endif
104 
105 /*
106  * sparsemem vmemmap imposes an additional requirement on the alignment of
107  * memstart_addr, due to the fact that the base of the vmemmap region
108  * has a direct correspondence, and needs to appear sufficiently aligned
109  * in the virtual address space.
110  */
111 #if defined(CONFIG_SPARSEMEM_VMEMMAP) && ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
112 #define ARM64_MEMSTART_ALIGN	(1UL << SECTION_SIZE_BITS)
113 #else
114 #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
115 #endif
116 
117 #endif	/* __ASM_KERNEL_PGTABLE_H */
118