mm/sparse.c

   1 /*
   2  * sparse memory mappings.
   3  */
   4 #include <linux/mm.h>
   5 #include <linux/mmzone.h>
   6 #include <linux/bootmem.h>
   7 #include <linux/highmem.h>
   8 #include <linux/module.h>
   9 #include <linux/spinlock.h>
  10 #include <linux/vmalloc.h>
  11 #include <asm/dma.h>
  12
  13 /*
  14  * Permanent SPARSEMEM data:
  15  *
  16  * 1) mem_section       - memory sections, mem_map's for valid memory
  17  */
  18 #ifdef CONFIG_SPARSEMEM_EXTREME
  19 struct mem_section *mem_section[NR_SECTION_ROOTS]
  20         ____cacheline_internodealigned_in_smp;
  21 #else
  22 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
  23         ____cacheline_internodealigned_in_smp;
  24 #endif
  25 EXPORT_SYMBOL(mem_section);
  26
  27 #ifdef CONFIG_SPARSEMEM_EXTREME
  28 static struct mem_section *sparse_index_alloc(int nid)
  29 {
  30         struct mem_section *section = NULL;
  31         unsigned long array_size = SECTIONS_PER_ROOT *
  32                                    sizeof(struct mem_section);
  33
  34         if (slab_is_available())
  35                 section = kmalloc_node(array_size, GFP_KERNEL, nid);
  36         else
  37                 section = alloc_bootmem_node(NODE_DATA(nid), array_size);
  38
  39         if (section)
  40                 memset(section, 0, array_size);
  41
  42         return section;
  43 }
  44
  45 static int sparse_index_init(unsigned long section_nr, int nid)
  46 {
  47         static DEFINE_SPINLOCK(index_init_lock);
  48         unsigned long root = SECTION_NR_TO_ROOT(section_nr);
  49         struct mem_section *section;
  50         int ret = 0;
  51
  52         if (mem_section[root])
  53                 return -EEXIST;
  54
  55         section = sparse_index_alloc(nid);
  56         /*
  57          * This lock keeps two different sections from
  58          * reallocating for the same index
  59          */
  60         spin_lock(&index_init_lock);
  61
  62         if (mem_section[root]) {
  63                 ret = -EEXIST;
  64                 goto out;
  65         }
  66
  67         mem_section[root] = section;
  68 out:
  69         spin_unlock(&index_init_lock);
  70         return ret;
  71 }
  72 #else /* !SPARSEMEM_EXTREME */
  73 static inline int sparse_index_init(unsigned long section_nr, int nid)
  74 {
  75         return 0;
  76 }
  77 #endif
  78
  79 /*
  80  * Although written for the SPARSEMEM_EXTREME case, this happens
  81  * to also work for the flat array case becase
  82  * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
  83  */
  84 int __section_nr(struct mem_section* ms)
  85 {
  86         unsigned long root_nr;
  87         struct mem_section* root;
  88
  89         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
  90                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
  91                 if (!root)
  92                         continue;
  93
  94                 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
  95                      break;
  96         }
  97
  98         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
  99 }
 100
 101 /*
 102  * During early boot, before section_mem_map is used for an actual
 103  * mem_map, we use section_mem_map to store the section's NUMA
 104  * node.  This keeps us from having to use another data structure.  The
 105  * node information is cleared just before we store the real mem_map.
 106  */
 107 static inline unsigned long sparse_encode_early_nid(int nid)
 108 {
 109         return (nid << SECTION_NID_SHIFT);
 110 }
 111
 112 static inline int sparse_early_nid(struct mem_section *section)
 113 {
 114         return (section->section_mem_map >> SECTION_NID_SHIFT);
 115 }
 116
 117 /* Record a memory area against a node. */
 118 void memory_present(int nid, unsigned long start, unsigned long end)
 119 {
 120         unsigned long pfn;
 121
 122         start &= PAGE_SECTION_MASK;
 123         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
 124                 unsigned long section = pfn_to_section_nr(pfn);
 125                 struct mem_section *ms;
 126
 127                 sparse_index_init(section, nid);
 128
 129                 ms = __nr_to_section(section);
 130                 if (!ms->section_mem_map)
 131                         ms->section_mem_map = sparse_encode_early_nid(nid) |
 132                                                         SECTION_MARKED_PRESENT;
 133         }
 134 }
 135
 136 /*
 137  * Only used by the i386 NUMA architecures, but relatively
 138  * generic code.
 139  */
 140 unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
 141                                                      unsigned long end_pfn)
 142 {
 143         unsigned long pfn;
 144         unsigned long nr_pages = 0;
 145
 146         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 147                 if (nid != early_pfn_to_nid(pfn))
 148                         continue;
 149
 150                 if (pfn_valid(pfn))
 151                         nr_pages += PAGES_PER_SECTION;
 152         }
 153
 154         return nr_pages * sizeof(struct page);
 155 }
 156
 157 /*
 158  * Subtle, we encode the real pfn into the mem_map such that
 159  * the identity pfn - section_mem_map will return the actual
 160  * physical page frame number.
 161  */
 162 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
 163 {
 164         return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
 165 }
 166
 167 /*
 168  * We need this if we ever free the mem_maps.  While not implemented yet,
 169  * this function is included for parity with its sibling.
 170  */
 171 static __attribute((unused))
 172 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
 173 {
 174         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
 175 }
 176
 177 static int sparse_init_one_section(struct mem_section *ms,
 178                 unsigned long pnum, struct page *mem_map)
 179 {
 180         if (!valid_section(ms))
 181                 return -EINVAL;
 182
 183         ms->section_mem_map &= ~SECTION_MAP_MASK;
 184         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum);
 185
 186         return 1;
 187 }
 188
 189 static struct page *sparse_early_mem_map_alloc(unsigned long pnum)
 190 {
 191         struct page *map;
 192         struct mem_section *ms = __nr_to_section(pnum);
 193         int nid = sparse_early_nid(ms);
 194
 195         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
 196         if (map)
 197                 return map;
 198
 199         map = alloc_bootmem_node(NODE_DATA(nid),
 200                         sizeof(struct page) * PAGES_PER_SECTION);
 201         if (map)
 202                 return map;
 203
 204         printk(KERN_WARNING "%s: allocation failed\n", __FUNCTION__);
 205         ms->section_mem_map = 0;
 206         return NULL;
 207 }
 208
 209 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
 210 {
 211         struct page *page, *ret;
 212         unsigned long memmap_size = sizeof(struct page) * nr_pages;
 213
 214         page = alloc_pages(GFP_KERNEL, get_order(memmap_size));
 215         if (page)
 216                 goto got_map_page;
 217
 218         ret = vmalloc(memmap_size);
 219         if (ret)
 220                 goto got_map_ptr;
 221
 222         return NULL;
 223 got_map_page:
 224         ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
 225 got_map_ptr:
 226         memset(ret, 0, memmap_size);
 227
 228         return ret;
 229 }
 230
 231 static int vaddr_in_vmalloc_area(void *addr)
 232 {
 233         if (addr >= (void *)VMALLOC_START &&
 234             addr < (void *)VMALLOC_END)
 235                 return 1;
 236         return 0;
 237 }
 238
 239 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 240 {
 241         if (vaddr_in_vmalloc_area(memmap))
 242                 vfree(memmap);
 243         else
 244                 free_pages((unsigned long)memmap,
 245                            get_order(sizeof(struct page) * nr_pages));
 246 }
 247
 248 /*
 249  * Allocate the accumulated non-linear sections, allocate a mem_map
 250  * for each and record the physical to section mapping.
 251  */
 252 void sparse_init(void)
 253 {
 254         unsigned long pnum;
 255         struct page *map;
 256
 257         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 258                 if (!valid_section_nr(pnum))
 259                         continue;
 260
 261                 map = sparse_early_mem_map_alloc(pnum);
 262                 if (!map)
 263                         continue;
 264                 sparse_init_one_section(__nr_to_section(pnum), pnum, map);
 265         }
 266 }
 267
 268 /*
 269  * returns the number of sections whose mem_maps were properly
 270  * set.  If this is <=0, then that means that the passed-in
 271  * map was not consumed and must be freed.
 272  */
 273 int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
 274                            int nr_pages)
 275 {
 276         unsigned long section_nr = pfn_to_section_nr(start_pfn);
 277         struct pglist_data *pgdat = zone->zone_pgdat;
 278         struct mem_section *ms;
 279         struct page *memmap;
 280         unsigned long flags;
 281         int ret;
 282
 283         /*
 284          * no locking for this, because it does its own
 285          * plus, it does a kmalloc
 286          */
 287         sparse_index_init(section_nr, pgdat->node_id);
 288         memmap = __kmalloc_section_memmap(nr_pages);
 289
 290         pgdat_resize_lock(pgdat, &flags);
 291
 292         ms = __pfn_to_section(start_pfn);
 293         if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
 294                 ret = -EEXIST;
 295                 goto out;
 296         }
 297         ms->section_mem_map |= SECTION_MARKED_PRESENT;
 298
 299         ret = sparse_init_one_section(ms, section_nr, memmap);
 300
 301 out:
 302         pgdat_resize_unlock(pgdat, &flags);
 303         if (ret <= 0)
 304                 __kfree_section_memmap(memmap, nr_pages);
 305         return ret;
 306 }