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 memmory 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/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(NODE_DATA(node), size, align, goal);
  44 }
  45
  46
  47 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
  48 {
  49         /* If the main allocator is up use that, fallback to bootmem. */
  50         if (slab_is_available()) {
  51                 struct page *page = alloc_pages_node(node,
  52                                 GFP_KERNEL | __GFP_ZERO, get_order(size));
  53                 if (page)
  54                         return page_address(page);
  55                 return NULL;
  56         } else
  57                 return __earlyonly_bootmem_alloc(node, size, size,
  58                                 __pa(MAX_DMA_ADDRESS));
  59 }
  60
  61 void __meminit vmemmap_verify(pte_t *pte, int node,
  62                                 unsigned long start, unsigned long end)
  63 {
  64         unsigned long pfn = pte_pfn(*pte);
  65         int actual_node = early_pfn_to_nid(pfn);
  66
  67         if (node_distance(actual_node, node) > LOCAL_DISTANCE)
  68                 printk(KERN_WARNING "[%lx-%lx] potential offnode "
  69                         "page_structs\n", start, end - 1);
  70 }
  71
  72 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
  73 {
  74         pte_t *pte = pte_offset_kernel(pmd, addr);
  75         if (pte_none(*pte)) {
  76                 pte_t entry;
  77                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
  78                 if (!p)
  79                         return NULL;
  80                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
  81                 set_pte_at(&init_mm, addr, pte, entry);
  82         }
  83         return pte;
  84 }
  85
  86 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
  87 {
  88         pmd_t *pmd = pmd_offset(pud, addr);
  89         if (pmd_none(*pmd)) {
  90                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
  91                 if (!p)
  92                         return NULL;
  93                 pmd_populate_kernel(&init_mm, pmd, p);
  94         }
  95         return pmd;
  96 }
  97
  98 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
  99 {
 100         pud_t *pud = pud_offset(pgd, addr);
 101         if (pud_none(*pud)) {
 102                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 103                 if (!p)
 104                         return NULL;
 105                 pud_populate(&init_mm, pud, p);
 106         }
 107         return pud;
 108 }
 109
 110 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 111 {
 112         pgd_t *pgd = pgd_offset_k(addr);
 113         if (pgd_none(*pgd)) {
 114                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 115                 if (!p)
 116                         return NULL;
 117                 pgd_populate(&init_mm, pgd, p);
 118         }
 119         return pgd;
 120 }
 121
 122 int __meminit vmemmap_populate_basepages(struct page *start_page,
 123                                                 unsigned long size, int node)
 124 {
 125         unsigned long addr = (unsigned long)start_page;
 126         unsigned long end = (unsigned long)(start_page + size);
 127         pgd_t *pgd;
 128         pud_t *pud;
 129         pmd_t *pmd;
 130         pte_t *pte;
 131
 132         for (; addr < end; addr += PAGE_SIZE) {
 133                 pgd = vmemmap_pgd_populate(addr, node);
 134                 if (!pgd)
 135                         return -ENOMEM;
 136                 pud = vmemmap_pud_populate(pgd, addr, node);
 137                 if (!pud)
 138                         return -ENOMEM;
 139                 pmd = vmemmap_pmd_populate(pud, addr, node);
 140                 if (!pmd)
 141                         return -ENOMEM;
 142                 pte = vmemmap_pte_populate(pmd, addr, node);
 143                 if (!pte)
 144                         return -ENOMEM;
 145                 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 146         }
 147
 148         return 0;
 149 }
 150
 151 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 152 {
 153         struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
 154         int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
 155         if (error)
 156                 return NULL;
 157
 158         return map;
 159 }