mm/sparse-vmemmap.c

   1 /*
   2  * Virtual Memory Map support
   3  *
   4  * (C) 2007 sgi. Christoph Lameter.
   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 memory 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/slab.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_high(NODE_DATA(node), size, align, goal);
  44 }
  45
  46 static void *vmemmap_buf;
  47 static void *vmemmap_buf_end;
  48
  49 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
  50 {
  51         /* If the main allocator is up use that, fallback to bootmem. */
  52         if (slab_is_available()) {
  53                 struct page *page;
  54
  55                 if (node_state(node, N_HIGH_MEMORY))
  56                         page = alloc_pages_node(
  57                                 node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  58                                 get_order(size));
  59                 else
  60                         page = alloc_pages(
  61                                 GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  62                                 get_order(size));
  63                 if (page)
  64                         return page_address(page);
  65                 return NULL;
  66         } else
  67                 return __earlyonly_bootmem_alloc(node, size, size,
  68                                 __pa(MAX_DMA_ADDRESS));
  69 }
  70
  71 /* need to make sure size is all the same during early stage */
  72 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
  73 {
  74         void *ptr;
  75
  76         if (!vmemmap_buf)
  77                 return vmemmap_alloc_block(size, node);
  78
  79         /* take the from buf */
  80         ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
  81         if (ptr + size > vmemmap_buf_end)
  82                 return vmemmap_alloc_block(size, node);
  83
  84         vmemmap_buf = ptr + size;
  85
  86         return ptr;
  87 }
  88
  89 void __meminit vmemmap_verify(pte_t *pte, int node,
  90                                 unsigned long start, unsigned long end)
  91 {
  92         unsigned long pfn = pte_pfn(*pte);
  93         int actual_node = early_pfn_to_nid(pfn);
  94
  95         if (node_distance(actual_node, node) > LOCAL_DISTANCE)
  96                 printk(KERN_WARNING "[%lx-%lx] potential offnode "
  97                         "page_structs\n", start, end - 1);
  98 }
  99
 100 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 101 {
 102         pte_t *pte = pte_offset_kernel(pmd, addr);
 103         if (pte_none(*pte)) {
 104                 pte_t entry;
 105                 void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
 106                 if (!p)
 107                         return NULL;
 108                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 109                 set_pte_at(&init_mm, addr, pte, entry);
 110         }
 111         return pte;
 112 }
 113
 114 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 115 {
 116         pmd_t *pmd = pmd_offset(pud, addr);
 117         if (pmd_none(*pmd)) {
 118                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 119                 if (!p)
 120                         return NULL;
 121                 pmd_populate_kernel(&init_mm, pmd, p);
 122         }
 123         return pmd;
 124 }
 125
 126 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
 127 {
 128         pud_t *pud = pud_offset(pgd, addr);
 129         if (pud_none(*pud)) {
 130                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 131                 if (!p)
 132                         return NULL;
 133                 pud_populate(&init_mm, pud, p);
 134         }
 135         return pud;
 136 }
 137
 138 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 139 {
 140         pgd_t *pgd = pgd_offset_k(addr);
 141         if (pgd_none(*pgd)) {
 142                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 143                 if (!p)
 144                         return NULL;
 145                 pgd_populate(&init_mm, pgd, p);
 146         }
 147         return pgd;
 148 }
 149
 150 int __meminit vmemmap_populate_basepages(unsigned long start,
 151                                          unsigned long end, int node)
 152 {
 153         unsigned long addr = start;
 154         pgd_t *pgd;
 155         pud_t *pud;
 156         pmd_t *pmd;
 157         pte_t *pte;
 158
 159         for (; addr < end; addr += PAGE_SIZE) {
 160                 pgd = vmemmap_pgd_populate(addr, node);
 161                 if (!pgd)
 162                         return -ENOMEM;
 163                 pud = vmemmap_pud_populate(pgd, addr, node);
 164                 if (!pud)
 165                         return -ENOMEM;
 166                 pmd = vmemmap_pmd_populate(pud, addr, node);
 167                 if (!pmd)
 168                         return -ENOMEM;
 169                 pte = vmemmap_pte_populate(pmd, addr, node);
 170                 if (!pte)
 171                         return -ENOMEM;
 172                 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 173         }
 174
 175         return 0;
 176 }
 177
 178 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 179 {
 180         unsigned long start;
 181         unsigned long end;
 182         struct page *map;
 183
 184         map = pfn_to_page(pnum * PAGES_PER_SECTION);
 185         start = (unsigned long)map;
 186         end = (unsigned long)(map + PAGES_PER_SECTION);
 187
 188         if (vmemmap_populate(start, end, nid))
 189                 return NULL;
 190
 191         return map;
 192 }
 193
 194 void __init sparse_mem_maps_populate_node(struct page **map_map,
 195                                           unsigned long pnum_begin,
 196                                           unsigned long pnum_end,
 197                                           unsigned long map_count, int nodeid)
 198 {
 199         unsigned long pnum;
 200         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 201         void *vmemmap_buf_start;
 202
 203         size = ALIGN(size, PMD_SIZE);
 204         vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
 205                          PMD_SIZE, __pa(MAX_DMA_ADDRESS));
 206
 207         if (vmemmap_buf_start) {
 208                 vmemmap_buf = vmemmap_buf_start;
 209                 vmemmap_buf_end = vmemmap_buf_start + size * map_count;
 210         }
 211
 212         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 213                 struct mem_section *ms;
 214
 215                 if (!present_section_nr(pnum))
 216                         continue;
 217
 218                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 219                 if (map_map[pnum])
 220                         continue;
 221                 ms = __nr_to_section(pnum);
 222                 printk(KERN_ERR "%s: sparsemem memory map backing failed "
 223                         "some memory will not be available.\n", __func__);
 224                 ms->section_mem_map = 0;
 225         }
 226
 227         if (vmemmap_buf_start) {
 228                 /* need to free left buf */
 229                 free_bootmem(__pa(vmemmap_buf), vmemmap_buf_end - vmemmap_buf);
 230                 vmemmap_buf = NULL;
 231                 vmemmap_buf_end = NULL;
 232         }
 233 }