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/memblock.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
  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_alloc_try_nid_raw(size, align, goal,
  45                                               MEMBLOCK_ALLOC_ACCESSIBLE, node);
  46}
  47
  48void * __meminit vmemmap_alloc_block(unsigned long size, int node)
  49{
  50        /* If the main allocator is up use that, fallback to bootmem. */
  51        if (slab_is_available()) {
  52                gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
  53                int order = get_order(size);
  54                static bool warned;
  55                struct page *page;
  56
  57                page = alloc_pages_node(node, gfp_mask, order);
  58                if (page)
  59                        return page_address(page);
  60
  61                if (!warned) {
  62                        warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
  63                                   "vmemmap alloc failure: order:%u", order);
  64                        warned = true;
  65                }
  66                return NULL;
  67        } else
  68                return __earlyonly_bootmem_alloc(node, size, size,
  69                                __pa(MAX_DMA_ADDRESS));
  70}
  71
  72static void * __meminit altmap_alloc_block_buf(unsigned long size,
  73                                               struct vmem_altmap *altmap);
  74
  75/* need to make sure size is all the same during early stage */
  76void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
  77                                         struct vmem_altmap *altmap)
  78{
  79        void *ptr;
  80
  81        if (altmap)
  82                return altmap_alloc_block_buf(size, altmap);
  83
  84        ptr = sparse_buffer_alloc(size);
  85        if (!ptr)
  86                ptr = vmemmap_alloc_block(size, node);
  87        return ptr;
  88}
  89
  90static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
  91{
  92        return altmap->base_pfn + altmap->reserve + altmap->alloc
  93                + altmap->align;
  94}
  95
  96static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
  97{
  98        unsigned long allocated = altmap->alloc + altmap->align;
  99
 100        if (altmap->free > allocated)
 101                return altmap->free - allocated;
 102        return 0;
 103}
 104
 105static void * __meminit altmap_alloc_block_buf(unsigned long size,
 106                                               struct vmem_altmap *altmap)
 107{
 108        unsigned long pfn, nr_pfns, nr_align;
 109
 110        if (size & ~PAGE_MASK) {
 111                pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
 112                                __func__, size);
 113                return NULL;
 114        }
 115
 116        pfn = vmem_altmap_next_pfn(altmap);
 117        nr_pfns = size >> PAGE_SHIFT;
 118        nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
 119        nr_align = ALIGN(pfn, nr_align) - pfn;
 120        if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
 121                return NULL;
 122
 123        altmap->alloc += nr_pfns;
 124        altmap->align += nr_align;
 125        pfn += nr_align;
 126
 127        pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
 128                        __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
 129        return __va(__pfn_to_phys(pfn));
 130}
 131
 132void __meminit vmemmap_verify(pte_t *pte, int node,
 133                                unsigned long start, unsigned long end)
 134{
 135        unsigned long pfn = pte_pfn(*pte);
 136        int actual_node = early_pfn_to_nid(pfn);
 137
 138        if (node_distance(actual_node, node) > LOCAL_DISTANCE)
 139                pr_warn("[%lx-%lx] potential offnode page_structs\n",
 140                        start, end - 1);
 141}
 142
 143pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
 144                                       struct vmem_altmap *altmap)
 145{
 146        pte_t *pte = pte_offset_kernel(pmd, addr);
 147        if (pte_none(*pte)) {
 148                pte_t entry;
 149                void *p;
 150
 151                p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
 152                if (!p)
 153                        return NULL;
 154                entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 155                set_pte_at(&init_mm, addr, pte, entry);
 156        }
 157        return pte;
 158}
 159
 160static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
 161{
 162        void *p = vmemmap_alloc_block(size, node);
 163
 164        if (!p)
 165                return NULL;
 166        memset(p, 0, size);
 167
 168        return p;
 169}
 170
 171pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 172{
 173        pmd_t *pmd = pmd_offset(pud, addr);
 174        if (pmd_none(*pmd)) {
 175                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 176                if (!p)
 177                        return NULL;
 178                pmd_populate_kernel(&init_mm, pmd, p);
 179        }
 180        return pmd;
 181}
 182
 183pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
 184{
 185        pud_t *pud = pud_offset(p4d, addr);
 186        if (pud_none(*pud)) {
 187                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 188                if (!p)
 189                        return NULL;
 190                pud_populate(&init_mm, pud, p);
 191        }
 192        return pud;
 193}
 194
 195p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
 196{
 197        p4d_t *p4d = p4d_offset(pgd, addr);
 198        if (p4d_none(*p4d)) {
 199                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 200                if (!p)
 201                        return NULL;
 202                p4d_populate(&init_mm, p4d, p);
 203        }
 204        return p4d;
 205}
 206
 207pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 208{
 209        pgd_t *pgd = pgd_offset_k(addr);
 210        if (pgd_none(*pgd)) {
 211                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 212                if (!p)
 213                        return NULL;
 214                pgd_populate(&init_mm, pgd, p);
 215        }
 216        return pgd;
 217}
 218
 219int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
 220                                         int node, struct vmem_altmap *altmap)
 221{
 222        unsigned long addr = start;
 223        pgd_t *pgd;
 224        p4d_t *p4d;
 225        pud_t *pud;
 226        pmd_t *pmd;
 227        pte_t *pte;
 228
 229        for (; addr < end; addr += PAGE_SIZE) {
 230                pgd = vmemmap_pgd_populate(addr, node);
 231                if (!pgd)
 232                        return -ENOMEM;
 233                p4d = vmemmap_p4d_populate(pgd, addr, node);
 234                if (!p4d)
 235                        return -ENOMEM;
 236                pud = vmemmap_pud_populate(p4d, 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, altmap);
 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 __populate_section_memmap(unsigned long pfn,
 252                unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 253{
 254        unsigned long start = (unsigned long) pfn_to_page(pfn);
 255        unsigned long end = start + nr_pages * sizeof(struct page);
 256
 257        if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
 258                !IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
 259                return NULL;
 260
 261        if (vmemmap_populate(start, end, nid, altmap))
 262                return NULL;
 263
 264        return pfn_to_page(pfn);
 265}
 266