mm/sparse-vmemmap.c

   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 #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
  40 static void * __ref __earlyonly_bootmem_alloc(int node,
  41                                 unsigned long size,
  42                                 unsigned long align,
  43                                 unsigned long goal)
  44 {
  45         return memblock_alloc_try_nid_raw(size, align, goal,
  46                                                MEMBLOCK_ALLOC_ACCESSIBLE, node);
  47 }
  48
  49 void * __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                 gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
  54                 int order = get_order(size);
  55                 static bool warned;
  56                 struct page *page;
  57
  58                 page = alloc_pages_node(node, gfp_mask, order);
  59                 if (page)
  60                         return page_address(page);
  61
  62                 if (!warned) {
  63                         warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
  64                                    "vmemmap alloc failure: order:%u", order);
  65                         warned = true;
  66                 }
  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 */
  74 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
  75 {
  76         void *ptr = sparse_buffer_alloc(size);
  77
  78         if (!ptr)
  79                 ptr = vmemmap_alloc_block(size, node);
  80         return ptr;
  81 }
  82
  83 static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
  84 {
  85         return altmap->base_pfn + altmap->reserve + altmap->alloc
  86                 + altmap->align;
  87 }
  88
  89 static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
  90 {
  91         unsigned long allocated = altmap->alloc + altmap->align;
  92
  93         if (altmap->free > allocated)
  94                 return altmap->free - allocated;
  95         return 0;
  96 }
  97
  98 /**
  99  * altmap_alloc_block_buf - allocate pages from the device page map
 100  * @altmap:     device page map
 101  * @size:       size (in bytes) of the allocation
 102  *
 103  * Allocations are aligned to the size of the request.
 104  */
 105 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
 132 void __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
 143 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 144 {
 145         pte_t *pte = pte_offset_kernel(pmd, addr);
 146         if (pte_none(*pte)) {
 147                 pte_t entry;
 148                 void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
 149                 if (!p)
 150                         return NULL;
 151                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
 152                 set_pte_at(&init_mm, addr, pte, entry);
 153         }
 154         return pte;
 155 }
 156
 157 static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
 158 {
 159         void *p = vmemmap_alloc_block(size, node);
 160
 161         if (!p)
 162                 return NULL;
 163         memset(p, 0, size);
 164
 165         return p;
 166 }
 167
 168 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 169 {
 170         pmd_t *pmd = pmd_offset(pud, addr);
 171         if (pmd_none(*pmd)) {
 172                 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 173                 if (!p)
 174                         return NULL;
 175                 pmd_populate_kernel(&init_mm, pmd, p);
 176         }
 177         return pmd;
 178 }
 179
 180 pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
 181 {
 182         pud_t *pud = pud_offset(p4d, addr);
 183         if (pud_none(*pud)) {
 184                 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 185                 if (!p)
 186                         return NULL;
 187                 pud_populate(&init_mm, pud, p);
 188         }
 189         return pud;
 190 }
 191
 192 p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
 193 {
 194         p4d_t *p4d = p4d_offset(pgd, addr);
 195         if (p4d_none(*p4d)) {
 196                 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 197                 if (!p)
 198                         return NULL;
 199                 p4d_populate(&init_mm, p4d, p);
 200         }
 201         return p4d;
 202 }
 203
 204 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
 205 {
 206         pgd_t *pgd = pgd_offset_k(addr);
 207         if (pgd_none(*pgd)) {
 208                 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
 209                 if (!p)
 210                         return NULL;
 211                 pgd_populate(&init_mm, pgd, p);
 212         }
 213         return pgd;
 214 }
 215
 216 int __meminit vmemmap_populate_basepages(unsigned long start,
 217                                          unsigned long end, int node)
 218 {
 219         unsigned long addr = start;
 220         pgd_t *pgd;
 221         p4d_t *p4d;
 222         pud_t *pud;
 223         pmd_t *pmd;
 224         pte_t *pte;
 225
 226         for (; addr < end; addr += PAGE_SIZE) {
 227                 pgd = vmemmap_pgd_populate(addr, node);
 228                 if (!pgd)
 229                         return -ENOMEM;
 230                 p4d = vmemmap_p4d_populate(pgd, addr, node);
 231                 if (!p4d)
 232                         return -ENOMEM;
 233                 pud = vmemmap_pud_populate(p4d, addr, node);
 234                 if (!pud)
 235                         return -ENOMEM;
 236                 pmd = vmemmap_pmd_populate(pud, addr, node);
 237                 if (!pmd)
 238                         return -ENOMEM;
 239                 pte = vmemmap_pte_populate(pmd, addr, node);
 240                 if (!pte)
 241                         return -ENOMEM;
 242                 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
 243         }
 244
 245         return 0;
 246 }
 247
 248 struct page * __meminit __populate_section_memmap(unsigned long pfn,
 249                 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 250 {
 251         unsigned long start;
 252         unsigned long end;
 253
 254         /*
 255          * The minimum granularity of memmap extensions is
 256          * PAGES_PER_SUBSECTION as allocations are tracked in the
 257          * 'subsection_map' bitmap of the section.
 258          */
 259         end = ALIGN(pfn + nr_pages, PAGES_PER_SUBSECTION);
 260         pfn &= PAGE_SUBSECTION_MASK;
 261         nr_pages = end - pfn;
 262
 263         start = (unsigned long) pfn_to_page(pfn);
 264         end = start + nr_pages * sizeof(struct page);
 265
 266         if (vmemmap_populate(start, end, nid, altmap))
 267                 return NULL;
 268
 269         return pfn_to_page(pfn);
 270 }