linux/mm/sparse-vmemmap.c at master · fabgithub/linux · GitHub

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* Virtual Memory Map support

* 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 memory 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/slab.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_high(NODE_DATA(node), size, align, goal);

}

static void *vmemmap_buf;

static void *vmemmap_buf_end;

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;

if (node_state(node, N_HIGH_MEMORY))

page = alloc_pages_node(

node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,

get_order(size));

else

page = alloc_pages(

GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,

get_order(size));

if (page)

return page_address(page);

return NULL;

} else

return __earlyonly_bootmem_alloc(node, size, size,

__pa(MAX_DMA_ADDRESS));

}

/* need to make sure size is all the same during early stage */

void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)

{

void *ptr;

if (!vmemmap_buf)

return vmemmap_alloc_block(size, node);

/* take the from buf */

ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);

if (ptr + size > vmemmap_buf_end)

return vmemmap_alloc_block(size, node);

vmemmap_buf = ptr + size;

return ptr;

}

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 (node_distance(actual_node, node) > LOCAL_DISTANCE)

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_buf(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(unsigned long start,

unsigned long end, int node)

{

unsigned long addr = start;

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)

{

unsigned long start;

unsigned long end;

struct page *map;

map = pfn_to_page(pnum * PAGES_PER_SECTION);

start = (unsigned long)map;

end = (unsigned long)(map + PAGES_PER_SECTION);

if (vmemmap_populate(start, end, nid))

return NULL;

return map;

}

void __init sparse_mem_maps_populate_node(struct page **map_map,

unsigned long pnum_begin,

unsigned long pnum_end,

unsigned long map_count, int nodeid)

{

unsigned long pnum;

unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;

void *vmemmap_buf_start;

size = ALIGN(size, PMD_SIZE);

vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,

PMD_SIZE, __pa(MAX_DMA_ADDRESS));

if (vmemmap_buf_start) {

vmemmap_buf = vmemmap_buf_start;

vmemmap_buf_end = vmemmap_buf_start + size * map_count;

}

for (pnum = pnum_begin; pnum < pnum_end; pnum++) {

struct mem_section *ms;

if (!present_section_nr(pnum))

continue;

map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);

if (map_map[pnum])

continue;

ms = __nr_to_section(pnum);

printk(KERN_ERR "%s: sparsemem memory map backing failed "

"some memory will not be available.\n", __func__);

ms->section_mem_map = 0;

}

if (vmemmap_buf_start) {

/* need to free left buf */

free_bootmem(__pa(vmemmap_buf), vmemmap_buf_end - vmemmap_buf);

vmemmap_buf = NULL;

vmemmap_buf_end = NULL;

}

linux/mm/sparse-vmemmap.c at master · fabgithub/linux · GitHub

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