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(
  57                                node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  58                                get_order(size));
  59                else
  60                        page = alloc_pages(
  61                                GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  62                                get_order(size));
  63                if (page)
  64                        return page_address(page);
  65                return NULL;
  66        } else
  67                return __earlyonly_bootmem_alloc(node, size, size,
  68                                __pa(MAX_DMA_ADDRESS));
  69}
  70
  71/* need to make sure size is all the same during early stage */
  72void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
  73{
  74        void *ptr;
  75
  76        if (!vmemmap_buf)
  77                return vmemmap_alloc_block(size, node);
  78
  79        /* take the from buf */
  80        ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
  81        if (ptr + size > vmemmap_buf_end)
  82                return vmemmap_alloc_block(size, node);
  83
  84        vmemmap_buf = ptr + size;
  85
  86        return ptr;
  87}
  88
  89void __meminit vmemmap_verify(pte_t *pte, int node,
  90                                unsigned long start, unsigned long end)
  91{
  92        unsigned long pfn = pte_pfn(*pte);
  93        int actual_node = early_pfn_to_nid(pfn);
  94
  95        if (node_distance(actual_node, node) > LOCAL_DISTANCE)
  96                printk(KERN_WARNING "[%lx-%lx] potential offnode "
  97                        "page_structs\n", start, end - 1);
  98}
  99
 100pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 101{
 102        pte_t *pte = pte_offset_kernel(pmd, addr);
 103        if (pte_none(*pte)) {
 104                pte_t entry;
 105                void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
 106                if (!p)
 107                        return NULL;
 108                entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 109                set_pte_at(&init_mm, addr, pte, entry);
 110        }
 111        return pte;
 112}
 113
 114pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 115{
 116        pmd_t *pmd = pmd_offset(pud, addr);
 117        if (pmd_none(*pmd)) {
 118                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 119                if (!p)
 120                        return NULL;
 121                pmd_populate_kernel(&init_mm, pmd, p);
 122        }
 123        return pmd;
 124}
 125
 126pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
 127{
 128        pud_t *pud = pud_offset(pgd, addr);
 129        if (pud_none(*pud)) {
 130                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 131                if (!p)
 132                        return NULL;
 133                pud_populate(&init_mm, pud, p);
 134        }
 135        return pud;
 136}
 137
 138pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 139{
 140        pgd_t *pgd = pgd_offset_k(addr);
 141        if (pgd_none(*pgd)) {
 142                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 143                if (!p)
 144                        return NULL;
 145                pgd_populate(&init_mm, pgd, p);
 146        }
 147        return pgd;
 148}
 149
 150int __meminit vmemmap_populate_basepages(unsigned long start,
 151                                         unsigned long end, int node)
 152{
 153        unsigned long addr = start;
 154        pgd_t *pgd;
 155        pud_t *pud;
 156        pmd_t *pmd;
 157        pte_t *pte;
 158
 159        for (; addr < end; addr += PAGE_SIZE) {
 160                pgd = vmemmap_pgd_populate(addr, node);
 161                if (!pgd)
 162                        return -ENOMEM;
 163                pud = vmemmap_pud_populate(pgd, addr, node);
 164                if (!pud)
 165                        return -ENOMEM;
 166                pmd = vmemmap_pmd_populate(pud, addr, node);
 167                if (!pmd)
 168                        return -ENOMEM;
 169                pte = vmemmap_pte_populate(pmd, addr, node);
 170                if (!pte)
 171                        return -ENOMEM;
 172                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 173        }
 174
 175        return 0;
 176}
 177
 178struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 179{
 180        unsigned long start;
 181        unsigned long end;
 182        struct page *map;
 183
 184        map = pfn_to_page(pnum * PAGES_PER_SECTION);
 185        start = (unsigned long)map;
 186        end = (unsigned long)(map + PAGES_PER_SECTION);
 187
 188        if (vmemmap_populate(start, end, nid))
 189                return NULL;
 190
 191        return map;
 192}
 193
 194void __init sparse_mem_maps_populate_node(struct page **map_map,
 195                                          unsigned long pnum_begin,
 196                                          unsigned long pnum_end,
 197                                          unsigned long map_count, int nodeid)
 198{
 199        unsigned long pnum;
 200        unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 201        void *vmemmap_buf_start;
 202
 203        size = ALIGN(size, PMD_SIZE);
 204        vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
 205                         PMD_SIZE, __pa(MAX_DMA_ADDRESS));
 206
 207        if (vmemmap_buf_start) {
 208                vmemmap_buf = vmemmap_buf_start;
 209                vmemmap_buf_end = vmemmap_buf_start + size * map_count;
 210        }
 211
 212        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 213                struct mem_section *ms;
 214
 215                if (!present_section_nr(pnum))
 216                        continue;
 217
 218                map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 219                if (map_map[pnum])
 220                        continue;
 221                ms = __nr_to_section(pnum);
 222                printk(KERN_ERR "%s: sparsemem memory map backing failed "
 223                        "some memory will not be available.\n", __func__);
 224                ms->section_mem_map = 0;
 225        }
 226
 227        if (vmemmap_buf_start) {
 228                /* need to free left buf */
 229                free_bootmem(__pa(vmemmap_buf), vmemmap_buf_end - vmemmap_buf);
 230                vmemmap_buf = NULL;
 231                vmemmap_buf_end = NULL;
 232        }
 233}
 234
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