mm/sparse-vmemmap.c

   1 /*
   2  * Virtual Memory Map support
   3  *
   4  * (C) 2007 sgi. Christoph Lameter <clameter@sgi.com>.
   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 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
  38 {
  39         /* If the main allocator is up use that, fallback to bootmem. */
  40         if (slab_is_available()) {
  41                 struct page *page = alloc_pages_node(node,
  42                                 GFP_KERNEL | __GFP_ZERO, get_order(size));
  43                 if (page)
  44                         return page_address(page);
  45                 return NULL;
  46         } else
  47                 return __alloc_bootmem_node(NODE_DATA(node), size, size,
  48                                 __pa(MAX_DMA_ADDRESS));
  49 }
  50
  51 void __meminit vmemmap_verify(pte_t *pte, int node,
  52                                 unsigned long start, unsigned long end)
  53 {
  54         unsigned long pfn = pte_pfn(*pte);
  55         int actual_node = early_pfn_to_nid(pfn);
  56
  57         if (actual_node != node)
  58                 printk(KERN_WARNING "[%lx-%lx] potential offnode "
  59                         "page_structs\n", start, end - 1);
  60 }
  61
  62 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
  63 {
  64         pte_t *pte = pte_offset_kernel(pmd, addr);
  65         if (pte_none(*pte)) {
  66                 pte_t entry;
  67                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
  68                 if (!p)
  69                         return 0;
  70                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
  71                 set_pte_at(&init_mm, addr, pte, entry);
  72         }
  73         return pte;
  74 }
  75
  76 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
  77 {
  78         pmd_t *pmd = pmd_offset(pud, addr);
  79         if (pmd_none(*pmd)) {
  80                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
  81                 if (!p)
  82                         return 0;
  83                 pmd_populate_kernel(&init_mm, pmd, p);
  84         }
  85         return pmd;
  86 }
  87
  88 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
  89 {
  90         pud_t *pud = pud_offset(pgd, addr);
  91         if (pud_none(*pud)) {
  92                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
  93                 if (!p)
  94                         return 0;
  95                 pud_populate(&init_mm, pud, p);
  96         }
  97         return pud;
  98 }
  99
 100 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 101 {
 102         pgd_t *pgd = pgd_offset_k(addr);
 103         if (pgd_none(*pgd)) {
 104                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 105                 if (!p)
 106                         return 0;
 107                 pgd_populate(&init_mm, pgd, p);
 108         }
 109         return pgd;
 110 }
 111
 112 int __meminit vmemmap_populate_basepages(struct page *start_page,
 113                                                 unsigned long size, int node)
 114 {
 115         unsigned long addr = (unsigned long)start_page;
 116         unsigned long end = (unsigned long)(start_page + size);
 117         pgd_t *pgd;
 118         pud_t *pud;
 119         pmd_t *pmd;
 120         pte_t *pte;
 121
 122         for (; addr < end; addr += PAGE_SIZE) {
 123                 pgd = vmemmap_pgd_populate(addr, node);
 124                 if (!pgd)
 125                         return -ENOMEM;
 126                 pud = vmemmap_pud_populate(pgd, addr, node);
 127                 if (!pud)
 128                         return -ENOMEM;
 129                 pmd = vmemmap_pmd_populate(pud, addr, node);
 130                 if (!pmd)
 131                         return -ENOMEM;
 132                 pte = vmemmap_pte_populate(pmd, addr, node);
 133                 if (!pte)
 134                         return -ENOMEM;
 135                 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 136         }
 137
 138         return 0;
 139 }
 140
 141 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 142 {
 143         struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
 144         int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
 145         if (error)
 146                 return NULL;
 147
 148         return map;
 149 }