1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  */
5 
6 #include <linux/stddef.h>
7 #include <linux/module.h>
8 #include <linux/memblock.h>
9 #include <linux/highmem.h>
10 #include <linux/mm.h>
11 #include <linux/swap.h>
12 #include <linux/slab.h>
13 #include <asm/fixmap.h>
14 #include <asm/page.h>
15 #include <as-layout.h>
16 #include <init.h>
17 #include <kern.h>
18 #include <kern_util.h>
19 #include <mem_user.h>
20 #include <os.h>
21 
22 /* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
23 unsigned long *empty_zero_page = NULL;
24 EXPORT_SYMBOL(empty_zero_page);
25 
26 /*
27  * Initialized during boot, and readonly for initializing page tables
28  * afterwards
29  */
30 pgd_t swapper_pg_dir[PTRS_PER_PGD];
31 
32 /* Initialized at boot time, and readonly after that */
33 unsigned long long highmem;
34 EXPORT_SYMBOL(highmem);
35 int kmalloc_ok = 0;
36 
37 /* Used during early boot */
38 static unsigned long brk_end;
39 
mem_init(void)40 void __init mem_init(void)
41 {
42 	/* clear the zero-page */
43 	memset(empty_zero_page, 0, PAGE_SIZE);
44 
45 	/* Map in the area just after the brk now that kmalloc is about
46 	 * to be turned on.
47 	 */
48 	brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
49 	map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
50 	memblock_free((void *)brk_end, uml_reserved - brk_end);
51 	uml_reserved = brk_end;
52 
53 	/* this will put all low memory onto the freelists */
54 	memblock_free_all();
55 	max_low_pfn = totalram_pages();
56 	max_pfn = max_low_pfn;
57 	kmalloc_ok = 1;
58 }
59 
60 /*
61  * Create a page table and place a pointer to it in a middle page
62  * directory entry.
63  */
one_page_table_init(pmd_t * pmd)64 static void __init one_page_table_init(pmd_t *pmd)
65 {
66 	if (pmd_none(*pmd)) {
67 		pte_t *pte = (pte_t *) memblock_alloc_low(PAGE_SIZE,
68 							  PAGE_SIZE);
69 		if (!pte)
70 			panic("%s: Failed to allocate %lu bytes align=%lx\n",
71 			      __func__, PAGE_SIZE, PAGE_SIZE);
72 
73 		set_pmd(pmd, __pmd(_KERNPG_TABLE +
74 					   (unsigned long) __pa(pte)));
75 		BUG_ON(pte != pte_offset_kernel(pmd, 0));
76 	}
77 }
78 
one_md_table_init(pud_t * pud)79 static void __init one_md_table_init(pud_t *pud)
80 {
81 #ifdef CONFIG_3_LEVEL_PGTABLES
82 	pmd_t *pmd_table = (pmd_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
83 	if (!pmd_table)
84 		panic("%s: Failed to allocate %lu bytes align=%lx\n",
85 		      __func__, PAGE_SIZE, PAGE_SIZE);
86 
87 	set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
88 	BUG_ON(pmd_table != pmd_offset(pud, 0));
89 #endif
90 }
91 
fixrange_init(unsigned long start,unsigned long end,pgd_t * pgd_base)92 static void __init fixrange_init(unsigned long start, unsigned long end,
93 				 pgd_t *pgd_base)
94 {
95 	pgd_t *pgd;
96 	p4d_t *p4d;
97 	pud_t *pud;
98 	pmd_t *pmd;
99 	int i, j;
100 	unsigned long vaddr;
101 
102 	vaddr = start;
103 	i = pgd_index(vaddr);
104 	j = pmd_index(vaddr);
105 	pgd = pgd_base + i;
106 
107 	for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
108 		p4d = p4d_offset(pgd, vaddr);
109 		pud = pud_offset(p4d, vaddr);
110 		if (pud_none(*pud))
111 			one_md_table_init(pud);
112 		pmd = pmd_offset(pud, vaddr);
113 		for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
114 			one_page_table_init(pmd);
115 			vaddr += PMD_SIZE;
116 		}
117 		j = 0;
118 	}
119 }
120 
fixaddr_user_init(void)121 static void __init fixaddr_user_init( void)
122 {
123 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
124 	long size = FIXADDR_USER_END - FIXADDR_USER_START;
125 	pte_t *pte;
126 	phys_t p;
127 	unsigned long v, vaddr = FIXADDR_USER_START;
128 
129 	if (!size)
130 		return;
131 
132 	fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
133 	v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
134 	if (!v)
135 		panic("%s: Failed to allocate %lu bytes align=%lx\n",
136 		      __func__, size, PAGE_SIZE);
137 
138 	memcpy((void *) v , (void *) FIXADDR_USER_START, size);
139 	p = __pa(v);
140 	for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
141 		      p += PAGE_SIZE) {
142 		pte = virt_to_kpte(vaddr);
143 		pte_set_val(*pte, p, PAGE_READONLY);
144 	}
145 #endif
146 }
147 
paging_init(void)148 void __init paging_init(void)
149 {
150 	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
151 	unsigned long vaddr;
152 
153 	empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
154 							       PAGE_SIZE);
155 	if (!empty_zero_page)
156 		panic("%s: Failed to allocate %lu bytes align=%lx\n",
157 		      __func__, PAGE_SIZE, PAGE_SIZE);
158 
159 	max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
160 	free_area_init(max_zone_pfn);
161 
162 	/*
163 	 * Fixed mappings, only the page table structure has to be
164 	 * created - mappings will be set by set_fixmap():
165 	 */
166 	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
167 	fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
168 
169 	fixaddr_user_init();
170 }
171 
172 /*
173  * This can't do anything because nothing in the kernel image can be freed
174  * since it's not in kernel physical memory.
175  */
176 
free_initmem(void)177 void free_initmem(void)
178 {
179 }
180 
181 /* Allocate and free page tables. */
182 
pgd_alloc(struct mm_struct * mm)183 pgd_t *pgd_alloc(struct mm_struct *mm)
184 {
185 	pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
186 
187 	if (pgd) {
188 		memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
189 		memcpy(pgd + USER_PTRS_PER_PGD,
190 		       swapper_pg_dir + USER_PTRS_PER_PGD,
191 		       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
192 	}
193 	return pgd;
194 }
195 
uml_kmalloc(int size,int flags)196 void *uml_kmalloc(int size, int flags)
197 {
198 	return kmalloc(size, flags);
199 }
200