1 files changed, 148 insertions, 0 deletions

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
new file mode 100644
index 000000000000..d3b718b0c20a
--- /dev/null
+++ b/mm/sparse-vmemmap.c
@@ -0,0 +1,148 @@
+/*
+ * Virtual Memory Map support
+ *
+ * (C) 2007 sgi. Christoph Lameter <clameter@sgi.com>.
+ *
+ * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
+ * virt_to_page, page_address() to be implemented as a base offset
+ * calculation without memory access.
+ *
+ * However, virtual mappings need a page table and TLBs. Many Linux
+ * architectures already map their physical space using 1-1 mappings
+ * via TLBs. For those arches the virtual memmory map is essentially
+ * for free if we use the same page size as the 1-1 mappings. In that
+ * case the overhead consists of a few additional pages that are
+ * allocated to create a view of memory for vmemmap.
+ *
+ * The architecture is expected to provide a vmemmap_populate() function
+ * to instantiate the mapping.
+ */
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+#include <asm/dma.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+/*
+ * Allocate a block of memory to be used to back the virtual memory map
+ * or to back the page tables that are used to create the mapping.
+ * Uses the main allocators if they are available, else bootmem.
+ */
+void * __meminit vmemmap_alloc_block(unsigned long size, int node)
+{
+        /* If the main allocator is up use that, fallback to bootmem. */
+        if (slab_is_available()) {
+                struct page *page = alloc_pages_node(node,
+                                GFP_KERNEL | __GFP_ZERO, get_order(size));
+                if (page)
+                        return page_address(page);
+                return NULL;
+        } else
+                return __alloc_bootmem_node(NODE_DATA(node), size, size,
+                                __pa(MAX_DMA_ADDRESS));
+}
+
+void __meminit vmemmap_verify(pte_t *pte, int node,
+                                unsigned long start, unsigned long end)
+{
+        unsigned long pfn = pte_pfn(*pte);
+        int actual_node = early_pfn_to_nid(pfn);
+
+        if (actual_node != node)
+                printk(KERN_WARNING "[%lx-%lx] potential offnode "
+                        "page_structs\n", start, end - 1);
+}
+
+pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
+{
+        pte_t *pte = pte_offset_kernel(pmd, addr);
+        if (pte_none(*pte)) {
+                pte_t entry;
+                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                if (!p)
+                        return 0;
+                entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
+                set_pte_at(&init_mm, addr, pte, entry);
+        }
+        return pte;
+}
+
+pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
+{
+        pmd_t *pmd = pmd_offset(pud, addr);
+        if (pmd_none(*pmd)) {
+                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                if (!p)
+                        return 0;
+                pmd_populate_kernel(&init_mm, pmd, p);
+        }
+        return pmd;
+}
+
+pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
+{
+        pud_t *pud = pud_offset(pgd, addr);
+        if (pud_none(*pud)) {
+                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                if (!p)
+                        return 0;
+                pud_populate(&init_mm, pud, p);
+        }
+        return pud;
+}
+
+pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
+{
+        pgd_t *pgd = pgd_offset_k(addr);
+        if (pgd_none(*pgd)) {
+                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                if (!p)
+                        return 0;
+                pgd_populate(&init_mm, pgd, p);
+        }
+        return pgd;
+}
+
+int __meminit vmemmap_populate_basepages(struct page *start_page,
+                                                unsigned long size, int node)
+{
+        unsigned long addr = (unsigned long)start_page;
+        unsigned long end = (unsigned long)(start_page + size);
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte;
+
+        for (; addr < end; addr += PAGE_SIZE) {
+                pgd = vmemmap_pgd_populate(addr, node);
+                if (!pgd)
+                        return -ENOMEM;
+                pud = vmemmap_pud_populate(pgd, addr, node);
+                if (!pud)
+                        return -ENOMEM;
+                pmd = vmemmap_pmd_populate(pud, addr, node);
+                if (!pmd)
+                        return -ENOMEM;
+                pte = vmemmap_pte_populate(pmd, addr, node);
+                if (!pte)
+                        return -ENOMEM;
+                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
+        }
+
+        return 0;
+}
+
+struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
+{
+        struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
+        int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
+        if (error)
+                return NULL;
+
+        return map;
+}