LXR linux/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 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/memremap.h>
  24#include <linux/highmem.h>
  25#include <linux/slab.h>
  26#include <linux/spinlock.h>
  27#include <linux/vmalloc.h>
  28#include <linux/sched.h>
  29#include <asm/dma.h>
  30#include <asm/pgalloc.h>
  31#include <asm/pgtable.h>
  32
  33/*
  34 * Allocate a block of memory to be used to back the virtual memory map
  35 * or to back the page tables that are used to create the mapping.
  36 * Uses the main allocators if they are available, else bootmem.
  37 */
  38
  39static void * __ref __earlyonly_bootmem_alloc(int node,
  40                                unsigned long size,
  41                                unsigned long align,
  42                                unsigned long goal)
  43{
  44        return memblock_virt_alloc_try_nid(size, align, goal,
  45                                            BOOTMEM_ALLOC_ACCESSIBLE, node);
  46}
  47
  48static void *vmemmap_buf;
  49static void *vmemmap_buf_end;
  50
  51void * __meminit vmemmap_alloc_block(unsigned long size, int node)
  52{
  53        /* If the main allocator is up use that, fallback to bootmem. */
  54        if (slab_is_available()) {
  55                struct page *page;
  56
  57                if (node_state(node, N_HIGH_MEMORY))
  58                        page = alloc_pages_node(
  59                                node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  60                                get_order(size));
  61                else
  62                        page = alloc_pages(
  63                                GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
  64                                get_order(size));
  65                if (page)
  66                        return page_address(page);
  67                return NULL;
  68        } else
  69                return __earlyonly_bootmem_alloc(node, size, size,
  70                                __pa(MAX_DMA_ADDRESS));
  71}
  72
  73/* need to make sure size is all the same during early stage */
  74static void * __meminit alloc_block_buf(unsigned long size, int node)
  75{
  76        void *ptr;
  77
  78        if (!vmemmap_buf)
  79                return vmemmap_alloc_block(size, node);
  80
  81        /* take the from buf */
  82        ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
  83        if (ptr + size > vmemmap_buf_end)
  84                return vmemmap_alloc_block(size, node);
  85
  86        vmemmap_buf = ptr + size;
  87
  88        return ptr;
  89}
  90
  91static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
  92{
  93        return altmap->base_pfn + altmap->reserve + altmap->alloc
  94                + altmap->align;
  95}
  96
  97static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
  98{
  99        unsigned long allocated = altmap->alloc + altmap->align;
 100
 101        if (altmap->free > allocated)
 102                return altmap->free - allocated;
 103        return 0;
 104}
 105
 106/**
 107 * vmem_altmap_alloc - allocate pages from the vmem_altmap reservation
 108 * @altmap - reserved page pool for the allocation
 109 * @nr_pfns - size (in pages) of the allocation
 110 *
 111 * Allocations are aligned to the size of the request
 112 */
 113static unsigned long __meminit vmem_altmap_alloc(struct vmem_altmap *altmap,
 114                unsigned long nr_pfns)
 115{
 116        unsigned long pfn = vmem_altmap_next_pfn(altmap);
 117        unsigned long nr_align;
 118
 119        nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
 120        nr_align = ALIGN(pfn, nr_align) - pfn;
 121
 122        if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
 123                return ULONG_MAX;
 124        altmap->alloc += nr_pfns;
 125        altmap->align += nr_align;
 126        return pfn + nr_align;
 127}
 128
 129static void * __meminit altmap_alloc_block_buf(unsigned long size,
 130                struct vmem_altmap *altmap)
 131{
 132        unsigned long pfn, nr_pfns;
 133        void *ptr;
 134
 135        if (size & ~PAGE_MASK) {
 136                pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
 137                                __func__, size);
 138                return NULL;
 139        }
 140
 141        nr_pfns = size >> PAGE_SHIFT;
 142        pfn = vmem_altmap_alloc(altmap, nr_pfns);
 143        if (pfn < ULONG_MAX)
 144                ptr = __va(__pfn_to_phys(pfn));
 145        else
 146                ptr = NULL;
 147        pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
 148                        __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
 149
 150        return ptr;
 151}
 152
 153/* need to make sure size is all the same during early stage */
 154void * __meminit __vmemmap_alloc_block_buf(unsigned long size, int node,
 155                struct vmem_altmap *altmap)
 156{
 157        if (altmap)
 158                return altmap_alloc_block_buf(size, altmap);
 159        return alloc_block_buf(size, node);
 160}
 161
 162void __meminit vmemmap_verify(pte_t *pte, int node,
 163                                unsigned long start, unsigned long end)
 164{
 165        unsigned long pfn = pte_pfn(*pte);
 166        int actual_node = early_pfn_to_nid(pfn);
 167
 168        if (node_distance(actual_node, node) > LOCAL_DISTANCE)
 169                pr_warn("[%lx-%lx] potential offnode page_structs\n",
 170                        start, end - 1);
 171}
 172
 173pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 174{
 175        pte_t *pte = pte_offset_kernel(pmd, addr);
 176        if (pte_none(*pte)) {
 177                pte_t entry;
 178                void *p = alloc_block_buf(PAGE_SIZE, node);
 179                if (!p)
 180                        return NULL;
 181                entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 182                set_pte_at(&init_mm, addr, pte, entry);
 183        }
 184        return pte;
 185}
 186
 187pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 188{
 189        pmd_t *pmd = pmd_offset(pud, addr);
 190        if (pmd_none(*pmd)) {
 191                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 192                if (!p)
 193                        return NULL;
 194                pmd_populate_kernel(&init_mm, pmd, p);
 195        }
 196        return pmd;
 197}
 198
 199pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
 200{
 201        pud_t *pud = pud_offset(pgd, addr);
 202        if (pud_none(*pud)) {
 203                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 204                if (!p)
 205                        return NULL;
 206                pud_populate(&init_mm, pud, p);
 207        }
 208        return pud;
 209}
 210
 211pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 212{
 213        pgd_t *pgd = pgd_offset_k(addr);
 214        if (pgd_none(*pgd)) {
 215                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
 216                if (!p)
 217                        return NULL;
 218                pgd_populate(&init_mm, pgd, p);
 219        }
 220        return pgd;
 221}
 222
 223int __meminit vmemmap_populate_basepages(unsigned long start,
 224                                         unsigned long end, int node)
 225{
 226        unsigned long addr = start;
 227        pgd_t *pgd;
 228        pud_t *pud;
 229        pmd_t *pmd;
 230        pte_t *pte;
 231
 232        for (; addr < end; addr += PAGE_SIZE) {
 233                pgd = vmemmap_pgd_populate(addr, node);
 234                if (!pgd)
 235                        return -ENOMEM;
 236                pud = vmemmap_pud_populate(pgd, addr, node);
 237                if (!pud)
 238                        return -ENOMEM;
 239                pmd = vmemmap_pmd_populate(pud, addr, node);
 240                if (!pmd)
 241                        return -ENOMEM;
 242                pte = vmemmap_pte_populate(pmd, addr, node);
 243                if (!pte)
 244                        return -ENOMEM;
 245                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 246        }
 247
 248        return 0;
 249}
 250
 251struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 252{
 253        unsigned long start;
 254        unsigned long end;
 255        struct page *map;
 256
 257        map = pfn_to_page(pnum * PAGES_PER_SECTION);
 258        start = (unsigned long)map;
 259        end = (unsigned long)(map + PAGES_PER_SECTION);
 260
 261        if (vmemmap_populate(start, end, nid))
 262                return NULL;
 263
 264        return map;
 265}
 266
 267void __init sparse_mem_maps_populate_node(struct page **map_map,
 268                                          unsigned long pnum_begin,
 269                                          unsigned long pnum_end,
 270                                          unsigned long map_count, int nodeid)
 271{
 272        unsigned long pnum;
 273        unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 274        void *vmemmap_buf_start;
 275
 276        size = ALIGN(size, PMD_SIZE);
 277        vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
 278                         PMD_SIZE, __pa(MAX_DMA_ADDRESS));
 279
 280        if (vmemmap_buf_start) {
 281                vmemmap_buf = vmemmap_buf_start;
 282                vmemmap_buf_end = vmemmap_buf_start + size * map_count;
 283        }
 284
 285        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 286                struct mem_section *ms;
 287
 288                if (!present_section_nr(pnum))
 289                        continue;
 290
 291                map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 292                if (map_map[pnum])
 293                        continue;
 294                ms = __nr_to_section(pnum);
 295                pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
 296                       __func__);
 297                ms->section_mem_map = 0;
 298        }
 299
 300        if (vmemmap_buf_start) {
 301                /* need to free left buf */
 302                memblock_free_early(__pa(vmemmap_buf),
 303                                    vmemmap_buf_end - vmemmap_buf);
 304                vmemmap_buf = NULL;
 305                vmemmap_buf_end = NULL;
 306        }
 307}
 308