mm/sparse.c

   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  */
  16 struct mem_section mem_section[NR_MEM_SECTIONS];
  17 EXPORT_SYMBOL(mem_section);
  18
  19 /* Record a memory area against a node. */
  20 void 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 = SECTION_MARKED_PRESENT;
  29         }
  30 }
  31
  32 /*
  33  * Only used by the i386 NUMA architecures, but relatively
  34  * generic code.
  35  */
  36 unsigned 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  * Subtle, we encode the real pfn into the mem_map such that
  55  * the identity pfn - section_mem_map will return the actual
  56  * physical page frame number.
  57  */
  58 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
  59 {
  60         return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
  61 }
  62
  63 /*
  64  * We need this if we ever free the mem_maps.  While not implemented yet,
  65  * this function is included for parity with its sibling.
  66  */
  67 static __attribute((unused))
  68 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
  69 {
  70         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
  71 }
  72
  73 static int sparse_init_one_section(struct mem_section *ms,
  74                 unsigned long pnum, struct page *mem_map)
  75 {
  76         if (!valid_section(ms))
  77                 return -EINVAL;
  78
  79         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum);
  80
  81         return 1;
  82 }
  83
  84 static struct page *sparse_early_mem_map_alloc(unsigned long pnum)
  85 {
  86         struct page *map;
  87         int nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
  88
  89         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
  90         if (map)
  91                 return map;
  92
  93         map = alloc_bootmem_node(NODE_DATA(nid),
  94                         sizeof(struct page) * PAGES_PER_SECTION);
  95         if (map)
  96                 return map;
  97
  98         printk(KERN_WARNING "%s: allocation failed\n", __FUNCTION__);
  99         mem_section[pnum].section_mem_map = 0;
 100         return NULL;
 101 }
 102
 103 /*
 104  * Allocate the accumulated non-linear sections, allocate a mem_map
 105  * for each and record the physical to section mapping.
 106  */
 107 void sparse_init(void)
 108 {
 109         unsigned long pnum;
 110         struct page *map;
 111
 112         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 113                 if (!valid_section_nr(pnum))
 114                         continue;
 115
 116                 map = sparse_early_mem_map_alloc(pnum);
 117                 if (map)
 118                         sparse_init_one_section(&mem_section[pnum], pnum, map);
 119         }
 120 }
 121
 122 /*
 123  * returns the number of sections whose mem_maps were properly
 124  * set.  If this is <=0, then that means that the passed-in
 125  * map was not consumed and must be freed.
 126  */
 127 int sparse_add_one_section(unsigned long start_pfn, int nr_pages, struct page *map)
 128 {
 129         struct mem_section *ms = __pfn_to_section(start_pfn);
 130
 131         if (ms->section_mem_map & SECTION_MARKED_PRESENT)
 132                 return -EEXIST;
 133
 134         ms->section_mem_map |= SECTION_MARKED_PRESENT;
 135
 136         return sparse_init_one_section(ms, pfn_to_section_nr(start_pfn), map);
 137 }