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/module.h>
  25 #include <linux/slab.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/sched.h>
  29 #include <asm/dma.h>
  30 #include <asm/pgalloc.h>
  31 #include <asm/pgtable.h>
  32
  33 /*
  34  * Allocate a block of memory to be used to back the virtual memory map
  35  * or to back the page tables that are used to create the mapping.
  36  * Uses the main allocators if they are available, else bootmem.
  37  */
  38
  39 static void * __init_refok __earlyonly_bootmem_alloc(int node,
  40                                 unsigned long size,
  41                                 unsigned long align,
  42                                 unsigned long goal)
  43 {
  44         return __alloc_bootmem_node_high(NODE_DATA(node), size, align, goal);
  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(node,
  58                                 GFP_KERNEL | __GFP_ZERO, get_order(size));
  59                 else
  60                         page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
  61                                 get_order(size));
  62                 if (page)
  63                         return page_address(page);
  64                 return NULL;
  65         } else
  66                 return __earlyonly_bootmem_alloc(node, size, size,
  67                                 __pa(MAX_DMA_ADDRESS));
  68 }
  69
  70 /* need to make sure size is all the same during early stage */
  71 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
  72 {
  73         void *ptr;
  74
  75         if (!vmemmap_buf)
  76                 return vmemmap_alloc_block(size, node);
  77
  78         /* take the from buf */
  79         ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
  80         if (ptr + size > vmemmap_buf_end)
  81                 return vmemmap_alloc_block(size, node);
  82
  83         vmemmap_buf = ptr + size;
  84
  85         return ptr;
  86 }
  87
  88 void __meminit vmemmap_verify(pte_t *pte, int node,
  89                                 unsigned long start, unsigned long end)
  90 {
  91         unsigned long pfn = pte_pfn(*pte);
  92         int actual_node = early_pfn_to_nid(pfn);
  93
  94         if (node_distance(actual_node, node) > LOCAL_DISTANCE)
  95                 printk(KERN_WARNING "[%lx-%lx] potential offnode "
  96                         "page_structs\n", start, end - 1);
  97 }
  98
  99 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 100 {
 101         pte_t *pte = pte_offset_kernel(pmd, addr);
 102         if (pte_none(*pte)) {
 103                 pte_t entry;
 104                 void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
 105                 if (!p)
 106                         return NULL;
 107                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 108                 set_pte_at(&init_mm, addr, pte, entry);
 109         }
 110         return pte;
 111 }
 112
 113 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 114 {
 115         pmd_t *pmd = pmd_offset(pud, addr);
 116         if (pmd_none(*pmd)) {
 117                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 118                 if (!p)
 119                         return NULL;
 120                 pmd_populate_kernel(&init_mm, pmd, p);
 121         }
 122         return pmd;
 123 }
 124
 125 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
 126 {
 127         pud_t *pud = pud_offset(pgd, addr);
 128         if (pud_none(*pud)) {
 129                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 130                 if (!p)
 131                         return NULL;
 132                 pud_populate(&init_mm, pud, p);
 133         }
 134         return pud;
 135 }
 136
 137 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 138 {
 139         pgd_t *pgd = pgd_offset_k(addr);
 140         if (pgd_none(*pgd)) {
 141                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 142                 if (!p)
 143                         return NULL;
 144                 pgd_populate(&init_mm, pgd, p);
 145         }
 146         return pgd;
 147 }
 148
 149 int __meminit vmemmap_populate_basepages(struct page *start_page,
 150                                                 unsigned long size, int node)
 151 {
 152         unsigned long addr = (unsigned long)start_page;
 153         unsigned long end = (unsigned long)(start_page + size);
 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         struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
 181         int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
 182         if (error)
 183                 return NULL;
 184
 185         return map;
 186 }
 187
 188 void __init sparse_mem_maps_populate_node(struct page **map_map,
 189                                           unsigned long pnum_begin,
 190                                           unsigned long pnum_end,
 191                                           unsigned long map_count, int nodeid)
 192 {
 193         unsigned long pnum;
 194         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 195         void *vmemmap_buf_start;
 196
 197         size = ALIGN(size, PMD_SIZE);
 198         vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
 199                          PMD_SIZE, __pa(MAX_DMA_ADDRESS));
 200
 201         if (vmemmap_buf_start) {
 202                 vmemmap_buf = vmemmap_buf_start;
 203                 vmemmap_buf_end = vmemmap_buf_start + size * map_count;
 204         }
 205
 206         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 207                 struct mem_section *ms;
 208
 209                 if (!present_section_nr(pnum))
 210                         continue;
 211
 212                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 213                 if (map_map[pnum])
 214                         continue;
 215                 ms = __nr_to_section(pnum);
 216                 printk(KERN_ERR "%s: sparsemem memory map backing failed "
 217                         "some memory will not be available.\n", __func__);
 218                 ms->section_mem_map = 0;
 219         }
 220
 221         if (vmemmap_buf_start) {
 222                 /* need to free left buf */
 223                 free_bootmem(__pa(vmemmap_buf), vmemmap_buf_end - vmemmap_buf);
 224                 vmemmap_buf = NULL;
 225                 vmemmap_buf_end = NULL;
 226         }
 227 }