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 memblock_virt_alloc_try_nid(size, align, goal,
  44                                             BOOTMEM_ALLOC_ACCESSIBLE, node);
  45 }
  46
  47 static void *vmemmap_buf;
  48 static void *vmemmap_buf_end;
  49
  50 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
  51 {
  52         /* If the main allocator is up use that, fallback to bootmem. */
  53         if (slab_is_available()) {
  54                 struct page *page;
  55
  56                 if (node_state(node, N_HIGH_MEMORY))
  57                         page = alloc_pages_node(
  58                                 node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  59                                 get_order(size));
  60                 else
  61                         page = alloc_pages(
  62                                 GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  63                                 get_order(size));
  64                 if (page)
  65                         return page_address(page);
  66                 return NULL;
  67         } else
  68                 return __earlyonly_bootmem_alloc(node, size, size,
  69                                 __pa(MAX_DMA_ADDRESS));
  70 }
  71
  72 /* need to make sure size is all the same during early stage */
  73 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
  74 {
  75         void *ptr;
  76
  77         if (!vmemmap_buf)
  78                 return vmemmap_alloc_block(size, node);
  79
  80         /* take the from buf */
  81         ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
  82         if (ptr + size > vmemmap_buf_end)
  83                 return vmemmap_alloc_block(size, node);
  84
  85         vmemmap_buf = ptr + size;
  86
  87         return ptr;
  88 }
  89
  90 void __meminit vmemmap_verify(pte_t *pte, int node,
  91                                 unsigned long start, unsigned long end)
  92 {
  93         unsigned long pfn = pte_pfn(*pte);
  94         int actual_node = early_pfn_to_nid(pfn);
  95
  96         if (node_distance(actual_node, node) > LOCAL_DISTANCE)
  97                 printk(KERN_WARNING "[%lx-%lx] potential offnode "
  98                         "page_structs\n", start, end - 1);
  99 }
 100
 101 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 102 {
 103         pte_t *pte = pte_offset_kernel(pmd, addr);
 104         if (pte_none(*pte)) {
 105                 pte_t entry;
 106                 void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
 107                 if (!p)
 108                         return NULL;
 109                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 110                 set_pte_at(&init_mm, addr, pte, entry);
 111         }
 112         return pte;
 113 }
 114
 115 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 116 {
 117         pmd_t *pmd = pmd_offset(pud, addr);
 118         if (pmd_none(*pmd)) {
 119                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 120                 if (!p)
 121                         return NULL;
 122                 pmd_populate_kernel(&init_mm, pmd, p);
 123         }
 124         return pmd;
 125 }
 126
 127 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
 128 {
 129         pud_t *pud = pud_offset(pgd, addr);
 130         if (pud_none(*pud)) {
 131                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 132                 if (!p)
 133                         return NULL;
 134                 pud_populate(&init_mm, pud, p);
 135         }
 136         return pud;
 137 }
 138
 139 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 140 {
 141         pgd_t *pgd = pgd_offset_k(addr);
 142         if (pgd_none(*pgd)) {
 143                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 144                 if (!p)
 145                         return NULL;
 146                 pgd_populate(&init_mm, pgd, p);
 147         }
 148         return pgd;
 149 }
 150
 151 int __meminit vmemmap_populate_basepages(unsigned long start,
 152                                          unsigned long end, int node)
 153 {
 154         unsigned long addr = start;
 155         pgd_t *pgd;
 156         pud_t *pud;
 157         pmd_t *pmd;
 158         pte_t *pte;
 159
 160         for (; addr < end; addr += PAGE_SIZE) {
 161                 pgd = vmemmap_pgd_populate(addr, node);
 162                 if (!pgd)
 163                         return -ENOMEM;
 164                 pud = vmemmap_pud_populate(pgd, addr, node);
 165                 if (!pud)
 166                         return -ENOMEM;
 167                 pmd = vmemmap_pmd_populate(pud, addr, node);
 168                 if (!pmd)
 169                         return -ENOMEM;
 170                 pte = vmemmap_pte_populate(pmd, addr, node);
 171                 if (!pte)
 172                         return -ENOMEM;
 173                 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 174         }
 175
 176         return 0;
 177 }
 178
 179 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 180 {
 181         unsigned long start;
 182         unsigned long end;
 183         struct page *map;
 184
 185         map = pfn_to_page(pnum * PAGES_PER_SECTION);
 186         start = (unsigned long)map;
 187         end = (unsigned long)(map + PAGES_PER_SECTION);
 188
 189         if (vmemmap_populate(start, end, nid))
 190                 return NULL;
 191
 192         return map;
 193 }
 194
 195 void __init sparse_mem_maps_populate_node(struct page **map_map,
 196                                           unsigned long pnum_begin,
 197                                           unsigned long pnum_end,
 198                                           unsigned long map_count, int nodeid)
 199 {
 200         unsigned long pnum;
 201         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 202         void *vmemmap_buf_start;
 203
 204         size = ALIGN(size, PMD_SIZE);
 205         vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
 206                          PMD_SIZE, __pa(MAX_DMA_ADDRESS));
 207
 208         if (vmemmap_buf_start) {
 209                 vmemmap_buf = vmemmap_buf_start;
 210                 vmemmap_buf_end = vmemmap_buf_start + size * map_count;
 211         }
 212
 213         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 214                 struct mem_section *ms;
 215
 216                 if (!present_section_nr(pnum))
 217                         continue;
 218
 219                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 220                 if (map_map[pnum])
 221                         continue;
 222                 ms = __nr_to_section(pnum);
 223                 printk(KERN_ERR "%s: sparsemem memory map backing failed "
 224                         "some memory will not be available.\n", __func__);
 225                 ms->section_mem_map = 0;
 226         }
 227
 228         if (vmemmap_buf_start) {
 229                 /* need to free left buf */
 230                 memblock_free_early(__pa(vmemmap_buf),
 231                                     vmemmap_buf_end - vmemmap_buf);
 232                 vmemmap_buf = NULL;
 233                 vmemmap_buf_end = NULL;
 234         }
 235 }