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/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
  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_virt_alloc_try_nid_raw(size, align, goal,
  46                                             BOOTMEM_ALLOC_ACCESSIBLE, node);
  47 }
  48
  49 static void *vmemmap_buf;
  50 static void *vmemmap_buf_end;
  51
  52 void * __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 */
  77 void * __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
  94 static 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
 100 static 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  */
 116 void * __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
 143 void __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
 154 pte_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
 168 static 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
 179 pmd_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
 191 pud_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
 203 p4d_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
 215 pgd_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
 227 int __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
 259 struct 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
 276 void __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 }