1 /*
2 * Virtual Memory Map support
3 *
4 * (C) 2007 sgi. Christoph Lameter <clameter@sgi.com>.
5 *
6 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
7 * virt_to_page, page_address() to be implemented as a base offset
8 * calculation without memory access.
9 *
10 * However, virtual mappings need a page table and TLBs. Many Linux
11 * architectures already map their physical space using 1-1 mappings
12 * via TLBs. For those arches the virtual memmory map is essentially
13 * for free if we use the same page size as the 1-1 mappings. In that
14 * case the overhead consists of a few additional pages that are
15 * allocated to create a view of memory for vmemmap.
16 *
17 * The architecture is expected to provide a vmemmap_populate() function
18 * to instantiate the mapping.
19 */
20 #include <linux/mm.h>
21 #include <linux/mmzone.h>
22 #include <linux/bootmem.h>
23 #include <linux/highmem.h>
24 #include <linux/module.h>
25 #include <linux/spinlock.h>
26 #include <linux/vmalloc.h>
27 #include <linux/sched.h>
28 #include <asm/dma.h>
29 #include <asm/pgalloc.h>
30 #include <asm/pgtable.h>
31
32 /*
33 * Allocate a block of memory to be used to back the virtual memory map
34 * or to back the page tables that are used to create the mapping.
35 * Uses the main allocators if they are available, else bootmem.
36 */
37
38 static void * __init_refok __earlyonly_bootmem_alloc(int node,
39 unsigned long size,
40 unsigned long align,
41 unsigned long goal)
42 {
43 return __alloc_bootmem_node(NODE_DATA(node), size, align, goal);
44 }
45
46
47 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
48 {
49 /* If the main allocator is up use that, fallback to bootmem. */
50 if (slab_is_available()) {
51 struct page *page = alloc_pages_node(node,
52 GFP_KERNEL | __GFP_ZERO, get_order(size));
53 if (page)
54 return page_address(page);
55 return NULL;
56 } else
57 return __earlyonly_bootmem_alloc(node, size, size,
58 __pa(MAX_DMA_ADDRESS));
59 }
60
61 void __meminit vmemmap_verify(pte_t *pte, int node,
62 unsigned long start, unsigned long end)
63 {
64 unsigned long pfn = pte_pfn(*pte);
65 int actual_node = early_pfn_to_nid(pfn);
66
67 if (actual_node != node)
68 printk(KERN_WARNING "[%lx-%lx] potential offnode "
69 "page_structs\n", start, end - 1);
70 }
71
72 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
73 {
74 pte_t *pte = pte_offset_kernel(pmd, addr);
75 if (pte_none(*pte)) {
76 pte_t entry;
77 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
78 if (!p)
79 return NULL;
80 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
81 set_pte_at(&init_mm, addr, pte, entry);
82 }
83 return pte;
84 }
85
86 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
87 {
88 pmd_t *pmd = pmd_offset(pud, addr);
89 if (pmd_none(*pmd)) {
90 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
91 if (!p)
92 return NULL;
93 pmd_populate_kernel(&init_mm, pmd, p);
94 }
95 return pmd;
96 }
97
98 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
99 {
100 pud_t *pud = pud_offset(pgd, addr);
101 if (pud_none(*pud)) {
102 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
103 if (!p)
104 return NULL;
105 pud_populate(&init_mm, pud, p);
106 }
107 return pud;
108 }
109
110 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
111 {
112 pgd_t *pgd = pgd_offset_k(addr);
113 if (pgd_none(*pgd)) {
114 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
115 if (!p)
116 return NULL;
117 pgd_populate(&init_mm, pgd, p);
118 }
119 return pgd;
120 }
121
122 int __meminit vmemmap_populate_basepages(struct page *start_page,
123 unsigned long size, int node)
124 {
125 unsigned long addr = (unsigned long)start_page;
126 unsigned long end = (unsigned long)(start_page + size);
127 pgd_t *pgd;
128 pud_t *pud;
129 pmd_t *pmd;
130 pte_t *pte;
131
132 for (; addr < end; addr += PAGE_SIZE) {
133 pgd = vmemmap_pgd_populate(addr, node);
134 if (!pgd)
135 return -ENOMEM;
136 pud = vmemmap_pud_populate(pgd, addr, node);
137 if (!pud)
138 return -ENOMEM;
139 pmd = vmemmap_pmd_populate(pud, addr, node);
140 if (!pmd)
141 return -ENOMEM;
142 pte = vmemmap_pte_populate(pmd, addr, node);
143 if (!pte)
144 return -ENOMEM;
145 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
146 }
147
148 return 0;
149 }
150
151 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
152 {
153 struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
154 int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
155 if (error)
156 return NULL;
157
158 return map;
159 }
160
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