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 /* need to make sure size is all the same during early stage */ 73 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node) 74 { 75 void *ptr = sparse_buffer_alloc(size); 76 77 if (!ptr) 78 ptr = vmemmap_alloc_block(size, node); 79 return ptr; 80 } 81 82 static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap) 83 { 84 return altmap->base_pfn + altmap->reserve + altmap->alloc 85 + altmap->align; 86 } 87 88 static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap) 89 { 90 unsigned long allocated = altmap->alloc + altmap->align; 91 92 if (altmap->free > allocated) 93 return altmap->free - allocated; 94 return 0; 95 } 96 97 /** 98 * altmap_alloc_block_buf - allocate pages from the device page map 99 * @altmap: device page map 100 * @size: size (in bytes) of the allocation 101 * 102 * Allocations are aligned to the size of the request. 103 */ 104 void * __meminit altmap_alloc_block_buf(unsigned long size, 105 struct vmem_altmap *altmap) 106 { 107 unsigned long pfn, nr_pfns, nr_align; 108 109 if (size & ~PAGE_MASK) { 110 pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n", 111 __func__, size); 112 return NULL; 113 } 114 115 pfn = vmem_altmap_next_pfn(altmap); 116 nr_pfns = size >> PAGE_SHIFT; 117 nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG); 118 nr_align = ALIGN(pfn, nr_align) - pfn; 119 if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap)) 120 return NULL; 121 122 altmap->alloc += nr_pfns; 123 altmap->align += nr_align; 124 pfn += nr_align; 125 126 pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n", 127 __func__, pfn, altmap->alloc, altmap->align, nr_pfns); 128 return __va(__pfn_to_phys(pfn)); 129 } 130 131 void __meminit vmemmap_verify(pte_t *pte, int node, 132 unsigned long start, unsigned long end) 133 { 134 unsigned long pfn = pte_pfn(*pte); 135 int actual_node = early_pfn_to_nid(pfn); 136 137 if (node_distance(actual_node, node) > LOCAL_DISTANCE) 138 pr_warn("[%lx-%lx] potential offnode page_structs\n", 139 start, end - 1); 140 } 141 142 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node, 143 struct vmem_altmap *altmap) 144 { 145 pte_t *pte = pte_offset_kernel(pmd, addr); 146 if (pte_none(*pte)) { 147 pte_t entry; 148 void *p; 149 150 if (altmap) 151 p = altmap_alloc_block_buf(PAGE_SIZE, altmap); 152 else 153 p = vmemmap_alloc_block_buf(PAGE_SIZE, node); 154 if (!p) 155 return NULL; 156 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL); 157 set_pte_at(&init_mm, addr, pte, entry); 158 } 159 return pte; 160 } 161 162 static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node) 163 { 164 void *p = vmemmap_alloc_block(size, node); 165 166 if (!p) 167 return NULL; 168 memset(p, 0, size); 169 170 return p; 171 } 172 173 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) 174 { 175 pmd_t *pmd = pmd_offset(pud, addr); 176 if (pmd_none(*pmd)) { 177 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 178 if (!p) 179 return NULL; 180 pmd_populate_kernel(&init_mm, pmd, p); 181 } 182 return pmd; 183 } 184 185 pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node) 186 { 187 pud_t *pud = pud_offset(p4d, addr); 188 if (pud_none(*pud)) { 189 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 190 if (!p) 191 return NULL; 192 pud_populate(&init_mm, pud, p); 193 } 194 return pud; 195 } 196 197 p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node) 198 { 199 p4d_t *p4d = p4d_offset(pgd, addr); 200 if (p4d_none(*p4d)) { 201 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 202 if (!p) 203 return NULL; 204 p4d_populate(&init_mm, p4d, p); 205 } 206 return p4d; 207 } 208 209 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) 210 { 211 pgd_t *pgd = pgd_offset_k(addr); 212 if (pgd_none(*pgd)) { 213 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 214 if (!p) 215 return NULL; 216 pgd_populate(&init_mm, pgd, p); 217 } 218 return pgd; 219 } 220 221 int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end, 222 int node, struct vmem_altmap *altmap) 223 { 224 unsigned long addr = start; 225 pgd_t *pgd; 226 p4d_t *p4d; 227 pud_t *pud; 228 pmd_t *pmd; 229 pte_t *pte; 230 231 for (; addr < end; addr += PAGE_SIZE) { 232 pgd = vmemmap_pgd_populate(addr, node); 233 if (!pgd) 234 return -ENOMEM; 235 p4d = vmemmap_p4d_populate(pgd, addr, node); 236 if (!p4d) 237 return -ENOMEM; 238 pud = vmemmap_pud_populate(p4d, addr, node); 239 if (!pud) 240 return -ENOMEM; 241 pmd = vmemmap_pmd_populate(pud, addr, node); 242 if (!pmd) 243 return -ENOMEM; 244 pte = vmemmap_pte_populate(pmd, addr, node, altmap); 245 if (!pte) 246 return -ENOMEM; 247 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); 248 } 249 250 return 0; 251 } 252 253 struct page * __meminit __populate_section_memmap(unsigned long pfn, 254 unsigned long nr_pages, int nid, struct vmem_altmap *altmap) 255 { 256 unsigned long start; 257 unsigned long end; 258 259 /* 260 * The minimum granularity of memmap extensions is 261 * PAGES_PER_SUBSECTION as allocations are tracked in the 262 * 'subsection_map' bitmap of the section. 263 */ 264 end = ALIGN(pfn + nr_pages, PAGES_PER_SUBSECTION); 265 pfn &= PAGE_SUBSECTION_MASK; 266 nr_pages = end - pfn; 267 268 start = (unsigned long) pfn_to_page(pfn); 269 end = start + nr_pages * sizeof(struct page); 270 271 if (vmemmap_populate(start, end, nid, altmap)) 272 return NULL; 273 274 return pfn_to_page(pfn); 275 } 276