sparse-vmemmap.c revision 29c71111d0557385328211b130246a90f9223b46 
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 <asm/dma.h>
28#include <asm/pgalloc.h>
29#include <asm/pgtable.h>
30
31/*
32 * Allocate a block of memory to be used to back the virtual memory map
33 * or to back the page tables that are used to create the mapping.
34 * Uses the main allocators if they are available, else bootmem.
35 */
36void * __meminit vmemmap_alloc_block(unsigned long size, int node)
37{
38	/* If the main allocator is up use that, fallback to bootmem. */
39	if (slab_is_available()) {
40		struct page *page = alloc_pages_node(node,
41				GFP_KERNEL | __GFP_ZERO, get_order(size));
42		if (page)
43			return page_address(page);
44		return NULL;
45	} else
46		return __alloc_bootmem_node(NODE_DATA(node), size, size,
47				__pa(MAX_DMA_ADDRESS));
48}
49
50void __meminit vmemmap_verify(pte_t *pte, int node,
51				unsigned long start, unsigned long end)
52{
53	unsigned long pfn = pte_pfn(*pte);
54	int actual_node = early_pfn_to_nid(pfn);
55
56	if (actual_node != node)
57		printk(KERN_WARNING "[%lx-%lx] potential offnode "
58			"page_structs\n", start, end - 1);
59}
60
61pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
62{
63	pte_t *pte = pte_offset_kernel(pmd, addr);
64	if (pte_none(*pte)) {
65		pte_t entry;
66		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
67		if (!p)
68			return 0;
69		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
70		set_pte_at(&init_mm, addr, pte, entry);
71	}
72	return pte;
73}
74
75pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
76{
77	pmd_t *pmd = pmd_offset(pud, addr);
78	if (pmd_none(*pmd)) {
79		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
80		if (!p)
81			return 0;
82		pmd_populate_kernel(&init_mm, pmd, p);
83	}
84	return pmd;
85}
86
87pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
88{
89	pud_t *pud = pud_offset(pgd, addr);
90	if (pud_none(*pud)) {
91		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
92		if (!p)
93			return 0;
94		pud_populate(&init_mm, pud, p);
95	}
96	return pud;
97}
98
99pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
100{
101	pgd_t *pgd = pgd_offset_k(addr);
102	if (pgd_none(*pgd)) {
103		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
104		if (!p)
105			return 0;
106		pgd_populate(&init_mm, pgd, p);
107	}
108	return pgd;
109}
110
111int __meminit vmemmap_populate_basepages(struct page *start_page,
112						unsigned long size, int node)
113{
114	unsigned long addr = (unsigned long)start_page;
115	unsigned long end = (unsigned long)(start_page + size);
116	pgd_t *pgd;
117	pud_t *pud;
118	pmd_t *pmd;
119	pte_t *pte;
120
121	for (; addr < end; addr += PAGE_SIZE) {
122		pgd = vmemmap_pgd_populate(addr, node);
123		if (!pgd)
124			return -ENOMEM;
125		pud = vmemmap_pud_populate(pgd, addr, node);
126		if (!pud)
127			return -ENOMEM;
128		pmd = vmemmap_pmd_populate(pud, addr, node);
129		if (!pmd)
130			return -ENOMEM;
131		pte = vmemmap_pte_populate(pmd, addr, node);
132		if (!pte)
133			return -ENOMEM;
134		vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
135	}
136
137	return 0;
138}
139
140struct page __init *sparse_early_mem_map_populate(unsigned long pnum, int nid)
141{
142	struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
143	int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
144	if (error)
145		return NULL;
146
147	return map;
148}
149