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