linux/mm/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
  38static 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
  46static void *vmemmap_buf;
  47static void *vmemmap_buf_end;
  48
  49void * __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 */
  70void * __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
  87void __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
  98pte_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
 112pmd_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
 124pud_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
 136pgd_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
 148int __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
 177struct 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
 187void __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}
 227
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