/*
* IA-32 Huge TLB Page Support for Kernel.
*
* Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
*/
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/sysctl.h>
#include <asm/mman.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
static unsigned long page_table_shareable(struct vm_area_struct *svma,
struct vm_area_struct *vma,
unsigned long addr, pgoff_t idx)
{
unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
svma->vm_start;
unsigned long sbase = saddr & PUD_MASK;
unsigned long s_end = sbase + PUD_SIZE;
/*
* match the virtual addresses, permission and the alignment of the
* page table page.
*/
if (pmd_index(addr) != pmd_index(saddr) ||
vma->vm_flags != svma->vm_flags ||
sbase < svma->vm_start || svma->vm_end < s_end)
return 0;
return saddr;
}
static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
{
unsigned long base = addr & PUD_MASK;
unsigned long end = base + PUD_SIZE;
/*
* check on proper vm_flags and page table alignment
*/
if (vma->vm_flags & VM_MAYSHARE &&
vma->vm_start <= base && end <= vma->vm_end)
return 1;
return 0;
}
/*
* search for a shareable pmd page for hugetlb.
*/
static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
{
struct vm_area_struct *vma = find_vma(mm, addr);
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
vma->vm_pgoff;
struct prio_tree_iter iter;
struct vm_area_struct *svma;
unsigned long saddr;
pte_t *spte = NULL;
if (!vma_shareable(vma, addr))
return;
spin_lock(&mapping->i_mmap_lock);
vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
if (svma == vma)
continue;
saddr = page_table_shareable(svma, vma, addr, idx);
if (saddr) {
spte = huge_pte_offset(svma->vm_mm, saddr);
if (spte) {
get_page(virt_to_page(spte));
break;
}
}
}
if (!spte)
goto out;
spin_lock(&mm->page_table_lock);
if (pud_none(*pud))
pud_populate(mm, pud, (unsigned long) spte & PAGE_MASK);
else
put_page(virt_to_page(spte));
spin_unlock(&mm->page_table_lock);
out:
spin_unlock(&mapping->i_mmap_lock);
}
/*
* unmap huge page backed by shared pte.
*
* Hugetlb pte page is ref counted at the time of mapping. If pte is shared
* indicated by page_count > 1, unmap is achieved by clearing pud and
* decrementing the ref count. If count == 1, the pte page is not shared.
*
* called with vma->vm_mm->page_table_lock held.
*
* returns: 1 successfully unmapped a shared pte page
* 0 the underlying pte page is not shared, or it is the last user
*/
int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
pgd_t *pgd = pgd_offset(mm, *addr);
pud_t *pud = pud_offset(pgd, *addr);
BUG_ON(page_count(virt_to_page(ptep)) == 0);
if (page_count(virt_to_page(ptep)) == 1)
return 0;
pud_clear(pud);
put_page(virt_to_page(ptep));
*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
return 1;
}
pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
pud_t *pud;
pte_t *pte = NULL;
pgd = pgd_offset(mm, addr);
pud = pud_alloc(mm, pgd, addr);
if (pud) {
if (pud_none(*pud))
huge_pmd_share(mm, addr, pud);
pte = (pte_t *) pmd_alloc(mm, pud, addr);
}
BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
return pte;
}
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd = NULL;
pgd = pgd_offset(mm, addr);
if (pgd_present(*pgd)) {
pud = pud_offset(pgd, addr);
if (pud_present(*pud))
pmd = pmd_offset(pud, addr);
}
return (pte_t *) pmd;
}
#if 0 /* This is just for testing */
struct page *
follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
{
unsigned long start = address;
int length = 1;
int nr;
struct page *page;
struct vm_area_struct *vma;
vma = find_vma(mm, addr);
if (!vma || !is_vm_hugetlb_page(vma))
return ERR_PTR(-EINVAL);
pte = huge_pte_offset(mm, address);
/* hugetlb should be locked, and hence, prefaulted */
WARN_ON(!pte || pte_none(*pte));
page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
WARN_ON(!PageCompound(page));
return page;
}
int pmd_huge(pmd_t pmd)
{
return 0;
}
struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
return NULL;
}
#else
struct page *
follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
{
return ERR_PTR(-EINVAL);
}
int pmd_huge(pmd_t pmd)
{
return !!(pmd_val(pmd) & _PAGE_PSE);
}
struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
struct page *page;
page = pte_page(*(pte_t *)pmd);
if (page)
page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
return page;
}
#endif
/* x86_64 also uses this file */
#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
unsigned long addr, unsigned long len,
unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long start_addr;
if (len > mm->cached_hole_size) {
start_addr = mm->free_area_cache;
} else {
start_addr = TASK_UNMAPPED_BASE;
mm->cached_hole_size = 0;
}
full_search:
addr = ALIGN(start_addr, HPAGE_SIZE);
for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
/* At this point: (!vma || addr < vma->vm_end). */
if (TASK_SIZE - len < addr) {
/*
* Start a new search - just in case we missed
* some holes.
*/
if (start_addr != TASK_UNMAPPED_BASE) {
start_addr = TASK_UNMAPPED_BASE;
mm->cached_hole_size = 0;
goto full_search;
}
return -ENOMEM;
}
if (!vma || addr + len <= vma->vm_start) {
mm->free_area_cache = addr + len;
return addr;
}
if (addr + mm->cached_hole_size < vma->vm_start)
mm->cached_hole_size = vma->vm_start - addr;
addr = ALIGN(vma->vm_end, HPAGE_SIZE);
}
}
static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
unsigned long addr0, unsigned long len,
unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma, *prev_vma;
unsigned long base = mm->mmap_base, addr = addr0;
unsigned long largest_hole = mm->cached_hole_size;
int first_time = 1;
/* don't allow allocations above current base */
if (mm->free_area_cache > base)
mm->free_area_cache = base;
if (len <= largest_hole) {
largest_hole = 0;
mm->free_area_cache = base;
}
try_again:
/* make sure it can fit in the remaining address space */
if (mm->free_area_cache < len)
goto fail;
/* either no address requested or cant fit in requested address hole */
addr = (mm->free_area_cache - len) & HPAGE_MASK;
do {
/*
* Lookup failure means no vma is above this address,
* i.e. return with success:
*/
if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
return addr;
/*
* new region fits between prev_vma->vm_end and
* vma->vm_start, use it:
*/
if (addr + len <= vma->vm_start &&
(!prev_vma || (addr >= prev_vma->vm_end))) {
/* remember the address as a hint for next time */
mm->cached_hole_size = largest_hole;
return (mm->free_area_cache = addr);
} else {
/* pull free_area_cache down to the first hole */
if (mm->free_area_cache == vma->vm_end) {
mm->free_area_cache = vma->vm_start;
mm->cached_hole_size = largest_hole;
}
}
/* remember the largest hole we saw so far */
if (addr + largest_hole < vma->vm_start)
largest_hole = vma->vm_start - addr;
/* try just below the current vma->vm_start */
addr = (vma->vm_start - len) & HPAGE_MASK;
} while (len <= vma->vm_start);
fail:
/*
* if hint left us with no space for the requested
* mapping then try again:
*/
if (first_time) {
mm->free_area_cache = base;
largest_hole = 0;
first_time = 0;
goto try_again;
}
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
* can happen with large stack limits and large mmap()
* allocations.
*/
mm->free_area_cache = TASK_UNMAPPED_BASE;
mm->cached_hole_size = ~0UL;
addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
len, pgoff, flags);
/*
* Restore the topdown base:
*/
mm->free_area_cache = base;
mm->cached_hole_size = ~0UL;
return addr;
}
unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
if (len & ~HPAGE_MASK)
return -EINVAL;
if (len > TASK_SIZE)
return -ENOMEM;
if (addr) {
addr = ALIGN(addr, HPAGE_SIZE);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
(!vma || addr + len <= vma->vm_start))
return addr;
}
if (mm->get_unmapped_area == arch_get_unmapped_area)
return hugetlb_get_unmapped_area_bottomup(file, addr, len,
pgoff, flags);
else
return hugetlb_get_unmapped_area_topdown(file, addr, len,
pgoff, flags);
}
#endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
