1 /* 2 * Virtual Memory Map support 3 * 4 * (C) 2007 sgi. Christoph Lameter <clameter@sgi.com>. 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/spinlock.h> 26 #include <linux/vmalloc.h> 27 #include <linux/sched.h> 28 #include <asm/dma.h> 29 #include <asm/pgalloc.h> 30 #include <asm/pgtable.h> 31 32 /* 33 * Allocate a block of memory to be used to back the virtual memory map 34 * or to back the page tables that are used to create the mapping. 35 * Uses the main allocators if they are available, else bootmem. 36 */ 37 38 static void * __init_refok __earlyonly_bootmem_alloc(int node, 39 unsigned long size, 40 unsigned long align, 41 unsigned long goal) 42 { 43 return __alloc_bootmem_node(NODE_DATA(node), size, align, goal); 44 } 45 46 47 void * __meminit vmemmap_alloc_block(unsigned long size, int node) 48 { 49 /* If the main allocator is up use that, fallback to bootmem. */ 50 if (slab_is_available()) { 51 struct page *page = alloc_pages_node(node, 52 GFP_KERNEL | __GFP_ZERO, get_order(size)); 53 if (page) 54 return page_address(page); 55 return NULL; 56 } else 57 return __earlyonly_bootmem_alloc(node, size, size, 58 __pa(MAX_DMA_ADDRESS)); 59 } 60 61 void __meminit vmemmap_verify(pte_t *pte, int node, 62 unsigned long start, unsigned long end) 63 { 64 unsigned long pfn = pte_pfn(*pte); 65 int actual_node = early_pfn_to_nid(pfn); 66 67 if (actual_node != node) 68 printk(KERN_WARNING "[%lx-%lx] potential offnode " 69 "page_structs\n", start, end - 1); 70 } 71 72 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node) 73 { 74 pte_t *pte = pte_offset_kernel(pmd, addr); 75 if (pte_none(*pte)) { 76 pte_t entry; 77 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 78 if (!p) 79 return 0; 80 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL); 81 set_pte_at(&init_mm, addr, pte, entry); 82 } 83 return pte; 84 } 85 86 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) 87 { 88 pmd_t *pmd = pmd_offset(pud, addr); 89 if (pmd_none(*pmd)) { 90 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 91 if (!p) 92 return 0; 93 pmd_populate_kernel(&init_mm, pmd, p); 94 } 95 return pmd; 96 } 97 98 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node) 99 { 100 pud_t *pud = pud_offset(pgd, addr); 101 if (pud_none(*pud)) { 102 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 103 if (!p) 104 return 0; 105 pud_populate(&init_mm, pud, p); 106 } 107 return pud; 108 } 109 110 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) 111 { 112 pgd_t *pgd = pgd_offset_k(addr); 113 if (pgd_none(*pgd)) { 114 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 115 if (!p) 116 return 0; 117 pgd_populate(&init_mm, pgd, p); 118 } 119 return pgd; 120 } 121 122 int __meminit vmemmap_populate_basepages(struct page *start_page, 123 unsigned long size, int node) 124 { 125 unsigned long addr = (unsigned long)start_page; 126 unsigned long end = (unsigned long)(start_page + size); 127 pgd_t *pgd; 128 pud_t *pud; 129 pmd_t *pmd; 130 pte_t *pte; 131 132 for (; addr < end; addr += PAGE_SIZE) { 133 pgd = vmemmap_pgd_populate(addr, node); 134 if (!pgd) 135 return -ENOMEM; 136 pud = vmemmap_pud_populate(pgd, addr, node); 137 if (!pud) 138 return -ENOMEM; 139 pmd = vmemmap_pmd_populate(pud, addr, node); 140 if (!pmd) 141 return -ENOMEM; 142 pte = vmemmap_pte_populate(pmd, addr, node); 143 if (!pte) 144 return -ENOMEM; 145 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); 146 } 147 148 return 0; 149 } 150 151 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid) 152 { 153 struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION); 154 int error = vmemmap_populate(map, PAGES_PER_SECTION, nid); 155 if (error) 156 return NULL; 157 158 return map; 159 } 160