/*
* 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.
*
* Special Kconfig settings:
*
* CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP
*
* The architecture has its own functions to populate the memory
* map and provides a vmemmap_populate function.
*
* CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP_PMD
*
* The architecture provides functions to populate the pmd level
* of the vmemmap mappings. Allowing mappings using large pages
* where available.
*
* If neither are set then PAGE_SIZE mappings are generated which
* require one PTE/TLB per PAGE_SIZE chunk of the virtual memory map.
*/
#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));
}
#ifndef CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP
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);
}
#ifndef CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP_PMD
static int __meminit vmemmap_populate_pte(pmd_t *pmd, unsigned long addr,
unsigned long end, int node)
{
pte_t *pte;
for (pte = pte_offset_kernel(pmd, addr); addr < end;
pte++, addr += PAGE_SIZE)
if (pte_none(*pte)) {
pte_t entry;
void *p = vmemmap_alloc_block(PAGE_SIZE, node);
if (!p)
return -ENOMEM;
entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
set_pte(pte, entry);
} else
vmemmap_verify(pte, node, addr + PAGE_SIZE, end);
return 0;
}
int __meminit vmemmap_populate_pmd(pud_t *pud, unsigned long addr,
unsigned long end, int node)
{
pmd_t *pmd;
int error = 0;
unsigned long next;
for (pmd = pmd_offset(pud, addr); addr < end && !error;
pmd++, addr = next) {
if (pmd_none(*pmd)) {
void *p = vmemmap_alloc_block(PAGE_SIZE, node);
if (!p)
return -ENOMEM;
pmd_populate_kernel(&init_mm, pmd, p);
} else
vmemmap_verify((pte_t *)pmd, node,
pmd_addr_end(addr, end), end);
next = pmd_addr_end(addr, end);
error = vmemmap_populate_pte(pmd, addr, next, node);
}
return error;
}
#endif /* CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP_PMD */
static int __meminit vmemmap_populate_pud(pgd_t *pgd, unsigned long addr,
unsigned long end, int node)
{
pud_t *pud;
int error = 0;
unsigned long next;
for (pud = pud_offset(pgd, addr); addr < end && !error;
pud++, addr = next) {
if (pud_none(*pud)) {
void *p = vmemmap_alloc_block(PAGE_SIZE, node);
if (!p)
return -ENOMEM;
pud_populate(&init_mm, pud, p);
}
next = pud_addr_end(addr, end);
error = vmemmap_populate_pmd(pud, addr, next, node);
}
return error;
}
int __meminit vmemmap_populate(struct page *start_page,
unsigned long nr, int node)
{
pgd_t *pgd;
unsigned long addr = (unsigned long)start_page;
unsigned long end = (unsigned long)(start_page + nr);
unsigned long next;
int error = 0;
printk(KERN_DEBUG "[%lx-%lx] Virtual memory section"
" (%ld pages) node %d\n", addr, end - 1, nr, node);
for (pgd = pgd_offset_k(addr); addr < end && !error;
pgd++, addr = next) {
if (pgd_none(*pgd)) {
void *p = vmemmap_alloc_block(PAGE_SIZE, node);
if (!p)
return -ENOMEM;
pgd_populate(&init_mm, pgd, p);
}
next = pgd_addr_end(addr,end);
error = vmemmap_populate_pud(pgd, addr, next, node);
}
return error;
}
#endif /* !CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP */
struct page __init *sparse_early_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;
}
