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
  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
  39 static 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
  48 void * __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
  72 static 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 */
  76 void * __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
  90 static 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
  96 static 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
 105 static 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                                        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
 160 static 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
 171 pmd_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
 183 pud_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
 195 p4d_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
 207 pgd_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
 219 int __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
 251 struct 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 }