linux/mm/sparse-vmemmap.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Virtual Memory Map support
   4 *
   5 * (C) 2007 sgi. Christoph Lameter.
   6 *
   7 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
   8 * virt_to_page, page_address() to be implemented as a base offset
   9 * calculation without memory access.
  10 *
  11 * However, virtual mappings need a page table and TLBs. Many Linux
  12 * architectures already map their physical space using 1-1 mappings
  13 * via TLBs. For those arches the virtual memory map is essentially
  14 * for free if we use the same page size as the 1-1 mappings. In that
  15 * case the overhead consists of a few additional pages that are
  16 * allocated to create a view of memory for vmemmap.
  17 *
  18 * The architecture is expected to provide a vmemmap_populate() function
  19 * to instantiate the mapping.
  20 */
  21#include <linux/mm.h>
  22#include <linux/mmzone.h>
  23#include <linux/bootmem.h>
  24#include <linux/memremap.h>
  25#include <linux/highmem.h>
  26#include <linux/slab.h>
  27#include <linux/spinlock.h>
  28#include <linux/vmalloc.h>
  29#include <linux/sched.h>
  30#include <asm/dma.h>
  31#include <asm/pgalloc.h>
  32#include <asm/pgtable.h>
  33
  34/*
  35 * Allocate a block of memory to be used to back the virtual memory map
  36 * or to back the page tables that are used to create the mapping.
  37 * Uses the main allocators if they are available, else bootmem.
  38 */
  39
  40static void * __ref __earlyonly_bootmem_alloc(int node,
  41                                unsigned long size,
  42                                unsigned long align,
  43                                unsigned long goal)
  44{
  45        return memblock_virt_alloc_try_nid_raw(size, align, goal,
  46                                            BOOTMEM_ALLOC_ACCESSIBLE, node);
  47}
  48
  49static void *vmemmap_buf;
  50static void *vmemmap_buf_end;
  51
  52void * __meminit vmemmap_alloc_block(unsigned long size, int node)
  53{
  54        /* If the main allocator is up use that, fallback to bootmem. */
  55        if (slab_is_available()) {
  56                gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
  57                int order = get_order(size);
  58                static bool warned;
  59                struct page *page;
  60
  61                page = alloc_pages_node(node, gfp_mask, order);
  62                if (page)
  63                        return page_address(page);
  64
  65                if (!warned) {
  66                        warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
  67                                   "vmemmap alloc failure: order:%u", order);
  68                        warned = true;
  69                }
  70                return NULL;
  71        } else
  72                return __earlyonly_bootmem_alloc(node, size, size,
  73                                __pa(MAX_DMA_ADDRESS));
  74}
  75
  76/* need to make sure size is all the same during early stage */
  77void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
  78{
  79        void *ptr;
  80
  81        if (!vmemmap_buf)
  82                return vmemmap_alloc_block(size, node);
  83
  84        /* take the from buf */
  85        ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
  86        if (ptr + size > vmemmap_buf_end)
  87                return vmemmap_alloc_block(size, node);
  88
  89        vmemmap_buf = ptr + size;
  90
  91        return ptr;
  92}
  93
  94static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
  95{
  96        return altmap->base_pfn + altmap->reserve + altmap->alloc
  97                + altmap->align;
  98}
  99
 100static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
 101{
 102        unsigned long allocated = altmap->alloc + altmap->align;
 103
 104        if (altmap->free > allocated)
 105                return altmap->free - allocated;
 106        return 0;
 107}
 108
 109/**
 110 * altmap_alloc_block_buf - allocate pages from the device page map
 111 * @altmap:     device page map
 112 * @size:       size (in bytes) of the allocation
 113 *
 114 * Allocations are aligned to the size of the request.
 115 */
 116void * __meminit altmap_alloc_block_buf(unsigned long size,
 117                struct vmem_altmap *altmap)
 118{
 119        unsigned long pfn, nr_pfns, nr_align;
 120
 121        if (size & ~PAGE_MASK) {
 122                pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
 123                                __func__, size);
 124                return NULL;
 125        }
 126
 127        pfn = vmem_altmap_next_pfn(altmap);
 128        nr_pfns = size >> PAGE_SHIFT;
 129        nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
 130        nr_align = ALIGN(pfn, nr_align) - pfn;
 131        if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
 132                return NULL;
 133
 134        altmap->alloc += nr_pfns;
 135        altmap->align += nr_align;
 136        pfn += nr_align;
 137
 138        pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
 139                        __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
 140        return __va(__pfn_to_phys(pfn));
 141}
 142
 143void __meminit vmemmap_verify(pte_t *pte, int node,
 144                                unsigned long start, unsigned long end)
 145{
 146        unsigned long pfn = pte_pfn(*pte);
 147        int actual_node = early_pfn_to_nid(pfn);
 148
 149        if (node_distance(actual_node, node) > LOCAL_DISTANCE)
 150                pr_warn("[%lx-%lx] potential offnode page_structs\n",
 151                        start, end - 1);
 152}
 153
 154pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 155{
 156        pte_t *pte = pte_offset_kernel(pmd, addr);
 157        if (pte_none(*pte)) {
 158                pte_t entry;
 159                void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
 160                if (!p)
 161                        return NULL;
 162                entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 163                set_pte_at(&init_mm, addr, pte, entry);
 164        }
 165        return pte;
 166}
 167
 168static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
 169{
 170        void *p = vmemmap_alloc_block(size, node);
 171
 172        if (!p)
 173                return NULL;
 174        memset(p, 0, size);
 175
 176        return p;
 177}
 178
 179pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 180{
 181        pmd_t *pmd = pmd_offset(pud, addr);
 182        if (pmd_none(*pmd)) {
 183                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 184                if (!p)
 185                        return NULL;
 186                pmd_populate_kernel(&init_mm, pmd, p);
 187        }
 188        return pmd;
 189}
 190
 191pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
 192{
 193        pud_t *pud = pud_offset(p4d, addr);
 194        if (pud_none(*pud)) {
 195                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 196                if (!p)
 197                        return NULL;
 198                pud_populate(&init_mm, pud, p);
 199        }
 200        return pud;
 201}
 202
 203p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
 204{
 205        p4d_t *p4d = p4d_offset(pgd, addr);
 206        if (p4d_none(*p4d)) {
 207                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 208                if (!p)
 209                        return NULL;
 210                p4d_populate(&init_mm, p4d, p);
 211        }
 212        return p4d;
 213}
 214
 215pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 216{
 217        pgd_t *pgd = pgd_offset_k(addr);
 218        if (pgd_none(*pgd)) {
 219                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 220                if (!p)
 221                        return NULL;
 222                pgd_populate(&init_mm, pgd, p);
 223        }
 224        return pgd;
 225}
 226
 227int __meminit vmemmap_populate_basepages(unsigned long start,
 228                                         unsigned long end, int node)
 229{
 230        unsigned long addr = start;
 231        pgd_t *pgd;
 232        p4d_t *p4d;
 233        pud_t *pud;
 234        pmd_t *pmd;
 235        pte_t *pte;
 236
 237        for (; addr < end; addr += PAGE_SIZE) {
 238                pgd = vmemmap_pgd_populate(addr, node);
 239                if (!pgd)
 240                        return -ENOMEM;
 241                p4d = vmemmap_p4d_populate(pgd, addr, node);
 242                if (!p4d)
 243                        return -ENOMEM;
 244                pud = vmemmap_pud_populate(p4d, addr, node);
 245                if (!pud)
 246                        return -ENOMEM;
 247                pmd = vmemmap_pmd_populate(pud, addr, node);
 248                if (!pmd)
 249                        return -ENOMEM;
 250                pte = vmemmap_pte_populate(pmd, addr, node);
 251                if (!pte)
 252                        return -ENOMEM;
 253                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 254        }
 255
 256        return 0;
 257}
 258
 259struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid,
 260                struct vmem_altmap *altmap)
 261{
 262        unsigned long start;
 263        unsigned long end;
 264        struct page *map;
 265
 266        map = pfn_to_page(pnum * PAGES_PER_SECTION);
 267        start = (unsigned long)map;
 268        end = (unsigned long)(map + PAGES_PER_SECTION);
 269
 270        if (vmemmap_populate(start, end, nid, altmap))
 271                return NULL;
 272
 273        return map;
 274}
 275
 276void __init sparse_mem_maps_populate_node(struct page **map_map,
 277                                          unsigned long pnum_begin,
 278                                          unsigned long pnum_end,
 279                                          unsigned long map_count, int nodeid)
 280{
 281        unsigned long pnum;
 282        unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 283        void *vmemmap_buf_start;
 284
 285        size = ALIGN(size, PMD_SIZE);
 286        vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
 287                         PMD_SIZE, __pa(MAX_DMA_ADDRESS));
 288
 289        if (vmemmap_buf_start) {
 290                vmemmap_buf = vmemmap_buf_start;
 291                vmemmap_buf_end = vmemmap_buf_start + size * map_count;
 292        }
 293
 294        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 295                struct mem_section *ms;
 296
 297                if (!present_section_nr(pnum))
 298                        continue;
 299
 300                map_map[pnum] = sparse_mem_map_populate(pnum, nodeid, NULL);
 301                if (map_map[pnum])
 302                        continue;
 303                ms = __nr_to_section(pnum);
 304                pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
 305                       __func__);
 306                ms->section_mem_map = 0;
 307        }
 308
 309        if (vmemmap_buf_start) {
 310                /* need to free left buf */
 311                memblock_free_early(__pa(vmemmap_buf),
 312                                    vmemmap_buf_end - vmemmap_buf);
 313                vmemmap_buf = NULL;
 314                vmemmap_buf_end = NULL;
 315        }
 316}
 317