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;
  52
  53                 if (node_state(node, N_HIGH_MEMORY))
  54                         page = alloc_pages_node(node,
  55                                 GFP_KERNEL | __GFP_ZERO, get_order(size));
  56                 else
  57                         page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
  58                                 get_order(size));
  59                 if (page)
  60                         return page_address(page);
  61                 return NULL;
  62         } else
  63                 return __earlyonly_bootmem_alloc(node, size, size,
  64                                 __pa(MAX_DMA_ADDRESS));
  65 }
  66
  67 void __meminit vmemmap_verify(pte_t *pte, int node,
  68                                 unsigned long start, unsigned long end)
  69 {
  70         unsigned long pfn = pte_pfn(*pte);
  71         int actual_node = early_pfn_to_nid(pfn);
  72
  73         if (node_distance(actual_node, node) > LOCAL_DISTANCE)
  74                 printk(KERN_WARNING "[%lx-%lx] potential offnode "
  75                         "page_structs\n", start, end - 1);
  76 }
  77
  78 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
  79 {
  80         pte_t *pte = pte_offset_kernel(pmd, addr);
  81         if (pte_none(*pte)) {
  82                 pte_t entry;
  83                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
  84                 if (!p)
  85                         return NULL;
  86                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
  87                 set_pte_at(&init_mm, addr, pte, entry);
  88         }
  89         return pte;
  90 }
  91
  92 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
  93 {
  94         pmd_t *pmd = pmd_offset(pud, addr);
  95         if (pmd_none(*pmd)) {
  96                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
  97                 if (!p)
  98                         return NULL;
  99                 pmd_populate_kernel(&init_mm, pmd, p);
 100         }
 101         return pmd;
 102 }
 103
 104 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
 105 {
 106         pud_t *pud = pud_offset(pgd, addr);
 107         if (pud_none(*pud)) {
 108                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 109                 if (!p)
 110                         return NULL;
 111                 pud_populate(&init_mm, pud, p);
 112         }
 113         return pud;
 114 }
 115
 116 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 117 {
 118         pgd_t *pgd = pgd_offset_k(addr);
 119         if (pgd_none(*pgd)) {
 120                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 121                 if (!p)
 122                         return NULL;
 123                 pgd_populate(&init_mm, pgd, p);
 124         }
 125         return pgd;
 126 }
 127
 128 int __meminit vmemmap_populate_basepages(struct page *start_page,
 129                                                 unsigned long size, int node)
 130 {
 131         unsigned long addr = (unsigned long)start_page;
 132         unsigned long end = (unsigned long)(start_page + size);
 133         pgd_t *pgd;
 134         pud_t *pud;
 135         pmd_t *pmd;
 136         pte_t *pte;
 137
 138         for (; addr < end; addr += PAGE_SIZE) {
 139                 pgd = vmemmap_pgd_populate(addr, node);
 140                 if (!pgd)
 141                         return -ENOMEM;
 142                 pud = vmemmap_pud_populate(pgd, addr, node);
 143                 if (!pud)
 144                         return -ENOMEM;
 145                 pmd = vmemmap_pmd_populate(pud, addr, node);
 146                 if (!pmd)
 147                         return -ENOMEM;
 148                 pte = vmemmap_pte_populate(pmd, addr, node);
 149                 if (!pte)
 150                         return -ENOMEM;
 151                 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 152         }
 153
 154         return 0;
 155 }
 156
 157 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 158 {
 159         struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
 160         int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
 161         if (error)
 162                 return NULL;
 163
 164         return map;
 165 }