xref: /openbmc/linux/arch/um/kernel/mem.c (revision 6da2ec56)
1 /*
2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3  * Licensed under the GPL
4  */
5 
6 #include <linux/stddef.h>
7 #include <linux/module.h>
8 #include <linux/bootmem.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 int kmalloc_ok = 0;
35 
36 /* Used during early boot */
37 static unsigned long brk_end;
38 
39 void __init mem_init(void)
40 {
41 	/* clear the zero-page */
42 	memset(empty_zero_page, 0, PAGE_SIZE);
43 
44 	/* Map in the area just after the brk now that kmalloc is about
45 	 * to be turned on.
46 	 */
47 	brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
48 	map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
49 	free_bootmem(__pa(brk_end), uml_reserved - brk_end);
50 	uml_reserved = brk_end;
51 
52 	/* this will put all low memory onto the freelists */
53 	free_all_bootmem();
54 	max_low_pfn = totalram_pages;
55 	max_pfn = totalram_pages;
56 	mem_init_print_info(NULL);
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  */
64 static void __init one_page_table_init(pmd_t *pmd)
65 {
66 	if (pmd_none(*pmd)) {
67 		pte_t *pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
68 		set_pmd(pmd, __pmd(_KERNPG_TABLE +
69 					   (unsigned long) __pa(pte)));
70 		if (pte != pte_offset_kernel(pmd, 0))
71 			BUG();
72 	}
73 }
74 
75 static void __init one_md_table_init(pud_t *pud)
76 {
77 #ifdef CONFIG_3_LEVEL_PGTABLES
78 	pmd_t *pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
79 	set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
80 	if (pmd_table != pmd_offset(pud, 0))
81 		BUG();
82 #endif
83 }
84 
85 static void __init fixrange_init(unsigned long start, unsigned long end,
86 				 pgd_t *pgd_base)
87 {
88 	pgd_t *pgd;
89 	pud_t *pud;
90 	pmd_t *pmd;
91 	int i, j;
92 	unsigned long vaddr;
93 
94 	vaddr = start;
95 	i = pgd_index(vaddr);
96 	j = pmd_index(vaddr);
97 	pgd = pgd_base + i;
98 
99 	for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
100 		pud = pud_offset(pgd, vaddr);
101 		if (pud_none(*pud))
102 			one_md_table_init(pud);
103 		pmd = pmd_offset(pud, vaddr);
104 		for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
105 			one_page_table_init(pmd);
106 			vaddr += PMD_SIZE;
107 		}
108 		j = 0;
109 	}
110 }
111 
112 static void __init fixaddr_user_init( void)
113 {
114 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
115 	long size = FIXADDR_USER_END - FIXADDR_USER_START;
116 	pgd_t *pgd;
117 	pud_t *pud;
118 	pmd_t *pmd;
119 	pte_t *pte;
120 	phys_t p;
121 	unsigned long v, vaddr = FIXADDR_USER_START;
122 
123 	if (!size)
124 		return;
125 
126 	fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
127 	v = (unsigned long) alloc_bootmem_low_pages(size);
128 	memcpy((void *) v , (void *) FIXADDR_USER_START, size);
129 	p = __pa(v);
130 	for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
131 		      p += PAGE_SIZE) {
132 		pgd = swapper_pg_dir + pgd_index(vaddr);
133 		pud = pud_offset(pgd, vaddr);
134 		pmd = pmd_offset(pud, vaddr);
135 		pte = pte_offset_kernel(pmd, vaddr);
136 		pte_set_val(*pte, p, PAGE_READONLY);
137 	}
138 #endif
139 }
140 
141 void __init paging_init(void)
142 {
143 	unsigned long zones_size[MAX_NR_ZONES], vaddr;
144 	int i;
145 
146 	empty_zero_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
147 	for (i = 0; i < ARRAY_SIZE(zones_size); i++)
148 		zones_size[i] = 0;
149 
150 	zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
151 		(uml_physmem >> PAGE_SHIFT);
152 	free_area_init(zones_size);
153 
154 	/*
155 	 * Fixed mappings, only the page table structure has to be
156 	 * created - mappings will be set by set_fixmap():
157 	 */
158 	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
159 	fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
160 
161 	fixaddr_user_init();
162 }
163 
164 /*
165  * This can't do anything because nothing in the kernel image can be freed
166  * since it's not in kernel physical memory.
167  */
168 
169 void free_initmem(void)
170 {
171 }
172 
173 #ifdef CONFIG_BLK_DEV_INITRD
174 void free_initrd_mem(unsigned long start, unsigned long end)
175 {
176 	free_reserved_area((void *)start, (void *)end, -1, "initrd");
177 }
178 #endif
179 
180 /* Allocate and free page tables. */
181 
182 pgd_t *pgd_alloc(struct mm_struct *mm)
183 {
184 	pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
185 
186 	if (pgd) {
187 		memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
188 		memcpy(pgd + USER_PTRS_PER_PGD,
189 		       swapper_pg_dir + USER_PTRS_PER_PGD,
190 		       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
191 	}
192 	return pgd;
193 }
194 
195 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
196 {
197 	free_page((unsigned long) pgd);
198 }
199 
200 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
201 {
202 	pte_t *pte;
203 
204 	pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
205 	return pte;
206 }
207 
208 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
209 {
210 	struct page *pte;
211 
212 	pte = alloc_page(GFP_KERNEL|__GFP_ZERO);
213 	if (!pte)
214 		return NULL;
215 	if (!pgtable_page_ctor(pte)) {
216 		__free_page(pte);
217 		return NULL;
218 	}
219 	return pte;
220 }
221 
222 #ifdef CONFIG_3_LEVEL_PGTABLES
223 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
224 {
225 	pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
226 
227 	if (pmd)
228 		memset(pmd, 0, PAGE_SIZE);
229 
230 	return pmd;
231 }
232 #endif
233 
234 void *uml_kmalloc(int size, int flags)
235 {
236 	return kmalloc(size, flags);
237 }
238