1 /* 2 * Virtual Memory Map support 3 * 4 * (C) 2007 sgi. Christoph Lameter. 5 * 6 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn, 7 * virt_to_page, page_address() to be implemented as a base offset 8 * calculation without memory access. 9 * 10 * However, virtual mappings need a page table and TLBs. Many Linux 11 * architectures already map their physical space using 1-1 mappings 12 * via TLBs. For those arches the virtual memmory map is essentially 13 * for free if we use the same page size as the 1-1 mappings. In that 14 * case the overhead consists of a few additional pages that are 15 * allocated to create a view of memory for vmemmap. 16 * 17 * The architecture is expected to provide a vmemmap_populate() function 18 * to instantiate the mapping. 19 */ 20 #include <linux/mm.h> 21 #include <linux/mmzone.h> 22 #include <linux/bootmem.h> 23 #include <linux/highmem.h> 24 #include <linux/module.h> 25 #include <linux/slab.h> 26 #include <linux/spinlock.h> 27 #include <linux/vmalloc.h> 28 #include <linux/sched.h> 29 #include <asm/dma.h> 30 #include <asm/pgalloc.h> 31 #include <asm/pgtable.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 * __init_refok __earlyonly_bootmem_alloc(int node, 40 unsigned long size, 41 unsigned long align, 42 unsigned long goal) 43 { 44 return __alloc_bootmem_node_high(NODE_DATA(node), size, align, goal); 45 } 46 47 static void *vmemmap_buf; 48 static void *vmemmap_buf_end; 49 50 void * __meminit vmemmap_alloc_block(unsigned long size, int node) 51 { 52 /* If the main allocator is up use that, fallback to bootmem. */ 53 if (slab_is_available()) { 54 struct page *page; 55 56 if (node_state(node, N_HIGH_MEMORY)) 57 page = alloc_pages_node(node, 58 GFP_KERNEL | __GFP_ZERO, get_order(size)); 59 else 60 page = alloc_pages(GFP_KERNEL | __GFP_ZERO, 61 get_order(size)); 62 if (page) 63 return page_address(page); 64 return NULL; 65 } else 66 return __earlyonly_bootmem_alloc(node, size, size, 67 __pa(MAX_DMA_ADDRESS)); 68 } 69 70 /* need to make sure size is all the same during early stage */ 71 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node) 72 { 73 void *ptr; 74 75 if (!vmemmap_buf) 76 return vmemmap_alloc_block(size, node); 77 78 /* take the from buf */ 79 ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size); 80 if (ptr + size > vmemmap_buf_end) 81 return vmemmap_alloc_block(size, node); 82 83 vmemmap_buf = ptr + size; 84 85 return ptr; 86 } 87 88 void __meminit vmemmap_verify(pte_t *pte, int node, 89 unsigned long start, unsigned long end) 90 { 91 unsigned long pfn = pte_pfn(*pte); 92 int actual_node = early_pfn_to_nid(pfn); 93 94 if (node_distance(actual_node, node) > LOCAL_DISTANCE) 95 printk(KERN_WARNING "[%lx-%lx] potential offnode " 96 "page_structs\n", start, end - 1); 97 } 98 99 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node) 100 { 101 pte_t *pte = pte_offset_kernel(pmd, addr); 102 if (pte_none(*pte)) { 103 pte_t entry; 104 void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node); 105 if (!p) 106 return NULL; 107 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL); 108 set_pte_at(&init_mm, addr, pte, entry); 109 } 110 return pte; 111 } 112 113 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) 114 { 115 pmd_t *pmd = pmd_offset(pud, addr); 116 if (pmd_none(*pmd)) { 117 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 118 if (!p) 119 return NULL; 120 pmd_populate_kernel(&init_mm, pmd, p); 121 } 122 return pmd; 123 } 124 125 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node) 126 { 127 pud_t *pud = pud_offset(pgd, addr); 128 if (pud_none(*pud)) { 129 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 130 if (!p) 131 return NULL; 132 pud_populate(&init_mm, pud, p); 133 } 134 return pud; 135 } 136 137 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) 138 { 139 pgd_t *pgd = pgd_offset_k(addr); 140 if (pgd_none(*pgd)) { 141 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 142 if (!p) 143 return NULL; 144 pgd_populate(&init_mm, pgd, p); 145 } 146 return pgd; 147 } 148 149 int __meminit vmemmap_populate_basepages(struct page *start_page, 150 unsigned long size, int node) 151 { 152 unsigned long addr = (unsigned long)start_page; 153 unsigned long end = (unsigned long)(start_page + size); 154 pgd_t *pgd; 155 pud_t *pud; 156 pmd_t *pmd; 157 pte_t *pte; 158 159 for (; addr < end; addr += PAGE_SIZE) { 160 pgd = vmemmap_pgd_populate(addr, node); 161 if (!pgd) 162 return -ENOMEM; 163 pud = vmemmap_pud_populate(pgd, addr, node); 164 if (!pud) 165 return -ENOMEM; 166 pmd = vmemmap_pmd_populate(pud, addr, node); 167 if (!pmd) 168 return -ENOMEM; 169 pte = vmemmap_pte_populate(pmd, addr, node); 170 if (!pte) 171 return -ENOMEM; 172 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); 173 } 174 175 return 0; 176 } 177 178 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid) 179 { 180 struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION); 181 int error = vmemmap_populate(map, PAGES_PER_SECTION, nid); 182 if (error) 183 return NULL; 184 185 return map; 186 } 187 188 void __init sparse_mem_maps_populate_node(struct page **map_map, 189 unsigned long pnum_begin, 190 unsigned long pnum_end, 191 unsigned long map_count, int nodeid) 192 { 193 unsigned long pnum; 194 unsigned long size = sizeof(struct page) * PAGES_PER_SECTION; 195 void *vmemmap_buf_start; 196 197 size = ALIGN(size, PMD_SIZE); 198 vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count, 199 PMD_SIZE, __pa(MAX_DMA_ADDRESS)); 200 201 if (vmemmap_buf_start) { 202 vmemmap_buf = vmemmap_buf_start; 203 vmemmap_buf_end = vmemmap_buf_start + size * map_count; 204 } 205 206 for (pnum = pnum_begin; pnum < pnum_end; pnum++) { 207 struct mem_section *ms; 208 209 if (!present_section_nr(pnum)) 210 continue; 211 212 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid); 213 if (map_map[pnum]) 214 continue; 215 ms = __nr_to_section(pnum); 216 printk(KERN_ERR "%s: sparsemem memory map backing failed " 217 "some memory will not be available.\n", __func__); 218 ms->section_mem_map = 0; 219 } 220 221 if (vmemmap_buf_start) { 222 /* need to free left buf */ 223 free_bootmem(__pa(vmemmap_buf), vmemmap_buf_end - vmemmap_buf); 224 vmemmap_buf = NULL; 225 vmemmap_buf_end = NULL; 226 } 227 } 228