root/mm/sparse-vmemmap.c

DEFINITIONS

1. __earlyonly_bootmem_alloc
2. vmemmap_alloc_block
3. vmemmap_verify
4. vmemmap_pte_populate
5. vmemmap_pmd_populate
6. vmemmap_pud_populate
7. vmemmap_pgd_populate
8. vmemmap_populate_basepages
9. sparse_mem_map_populate

/*
 * Virtual Memory Map support
 *
 * (C) 2007 sgi. Christoph Lameter.
 *
 * 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 <linux/sched.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.
 */

static void * __init_refok __earlyonly_bootmem_alloc(int node,
                                unsigned long size,
                                unsigned long align,
                                unsigned long goal)
{
        return __alloc_bootmem_node(NODE_DATA(node), size, align, goal);
}


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 __earlyonly_bootmem_alloc(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 NULL;
                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 NULL;
                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 NULL;
                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 NULL;
                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;
}