sparse.c revision d41dee369bff3b9dcb6328d4d822926c28cc2594 
1/*
2 * sparse memory mappings.
3 */
4#include <linux/config.h>
5#include <linux/mm.h>
6#include <linux/mmzone.h>
7#include <linux/bootmem.h>
8#include <linux/module.h>
9#include <asm/dma.h>
10
11/*
12 * Permanent SPARSEMEM data:
13 *
14 * 1) mem_section	- memory sections, mem_map's for valid memory
15 */
16struct mem_section mem_section[NR_MEM_SECTIONS];
17EXPORT_SYMBOL(mem_section);
18
19/* Record a memory area against a node. */
20void memory_present(int nid, unsigned long start, unsigned long end)
21{
22	unsigned long pfn;
23
24	start &= PAGE_SECTION_MASK;
25	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
26		unsigned long section = pfn_to_section_nr(pfn);
27		if (!mem_section[section].section_mem_map)
28			mem_section[section].section_mem_map = (void *) -1;
29	}
30}
31
32/*
33 * Only used by the i386 NUMA architecures, but relatively
34 * generic code.
35 */
36unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
37						     unsigned long end_pfn)
38{
39	unsigned long pfn;
40	unsigned long nr_pages = 0;
41
42	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
43		if (nid != early_pfn_to_nid(pfn))
44			continue;
45
46		if (pfn_valid(pfn))
47			nr_pages += PAGES_PER_SECTION;
48	}
49
50	return nr_pages * sizeof(struct page);
51}
52
53/*
54 * Allocate the accumulated non-linear sections, allocate a mem_map
55 * for each and record the physical to section mapping.
56 */
57void sparse_init(void)
58{
59	unsigned long pnum;
60	struct page *map;
61	int nid;
62
63	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
64		if (!mem_section[pnum].section_mem_map)
65			continue;
66
67		nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
68		map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
69		if (!map)
70			map = alloc_bootmem_node(NODE_DATA(nid),
71				sizeof(struct page) * PAGES_PER_SECTION);
72		if (!map) {
73			mem_section[pnum].section_mem_map = 0;
74			continue;
75		}
76
77		/*
78		 * Subtle, we encode the real pfn into the mem_map such that
79		 * the identity pfn - section_mem_map will return the actual
80		 * physical page frame number.
81		 */
82		mem_section[pnum].section_mem_map = map -
83						section_nr_to_pfn(pnum);
84	}
85}
86