sparse-vmemmap.c

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    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 }

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FreeBSD/Linux Kernel Cross Reference sys/mm/sparse-vmemmap.c

FreeBSD/Linux Kernel Cross Reference
sys/mm/sparse-vmemmap.c