448 lines
10 KiB
C
448 lines
10 KiB
C
/*
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* IA-32 Huge TLB Page Support for Kernel.
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*
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* Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
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*/
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <linux/err.h>
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#include <linux/sysctl.h>
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#include <asm/mman.h>
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#include <asm/tlb.h>
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#include <asm/tlbflush.h>
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#include <asm/pgalloc.h>
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static unsigned long page_table_shareable(struct vm_area_struct *svma,
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struct vm_area_struct *vma,
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unsigned long addr, pgoff_t idx)
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{
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unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
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svma->vm_start;
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unsigned long sbase = saddr & PUD_MASK;
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unsigned long s_end = sbase + PUD_SIZE;
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/* Allow segments to share if only one is marked locked */
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unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;
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unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;
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/*
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* match the virtual addresses, permission and the alignment of the
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* page table page.
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*/
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if (pmd_index(addr) != pmd_index(saddr) ||
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vm_flags != svm_flags ||
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sbase < svma->vm_start || svma->vm_end < s_end)
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return 0;
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return saddr;
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}
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static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
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{
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unsigned long base = addr & PUD_MASK;
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unsigned long end = base + PUD_SIZE;
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/*
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* check on proper vm_flags and page table alignment
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*/
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if (vma->vm_flags & VM_MAYSHARE &&
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vma->vm_start <= base && end <= vma->vm_end)
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return 1;
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return 0;
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}
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/*
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* search for a shareable pmd page for hugetlb.
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*/
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static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
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{
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struct vm_area_struct *vma = find_vma(mm, addr);
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struct address_space *mapping = vma->vm_file->f_mapping;
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pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
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vma->vm_pgoff;
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struct prio_tree_iter iter;
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struct vm_area_struct *svma;
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unsigned long saddr;
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pte_t *spte = NULL;
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if (!vma_shareable(vma, addr))
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return;
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spin_lock(&mapping->i_mmap_lock);
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vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
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if (svma == vma)
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continue;
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saddr = page_table_shareable(svma, vma, addr, idx);
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if (saddr) {
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spte = huge_pte_offset(svma->vm_mm, saddr);
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if (spte) {
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get_page(virt_to_page(spte));
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break;
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}
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}
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}
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if (!spte)
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goto out;
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spin_lock(&mm->page_table_lock);
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if (pud_none(*pud))
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pud_populate(mm, pud, (pmd_t *)((unsigned long)spte & PAGE_MASK));
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else
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put_page(virt_to_page(spte));
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spin_unlock(&mm->page_table_lock);
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out:
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spin_unlock(&mapping->i_mmap_lock);
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}
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/*
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* unmap huge page backed by shared pte.
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*
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* Hugetlb pte page is ref counted at the time of mapping. If pte is shared
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* indicated by page_count > 1, unmap is achieved by clearing pud and
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* decrementing the ref count. If count == 1, the pte page is not shared.
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*
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* called with vma->vm_mm->page_table_lock held.
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*
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* returns: 1 successfully unmapped a shared pte page
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* 0 the underlying pte page is not shared, or it is the last user
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*/
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int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
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{
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pgd_t *pgd = pgd_offset(mm, *addr);
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pud_t *pud = pud_offset(pgd, *addr);
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BUG_ON(page_count(virt_to_page(ptep)) == 0);
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if (page_count(virt_to_page(ptep)) == 1)
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return 0;
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pud_clear(pud);
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put_page(virt_to_page(ptep));
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*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
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return 1;
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}
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pte_t *huge_pte_alloc(struct mm_struct *mm,
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unsigned long addr, unsigned long sz)
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{
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pgd_t *pgd;
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pud_t *pud;
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pte_t *pte = NULL;
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pgd = pgd_offset(mm, addr);
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pud = pud_alloc(mm, pgd, addr);
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if (pud) {
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if (sz == PUD_SIZE) {
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pte = (pte_t *)pud;
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} else {
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BUG_ON(sz != PMD_SIZE);
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if (pud_none(*pud))
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huge_pmd_share(mm, addr, pud);
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pte = (pte_t *) pmd_alloc(mm, pud, addr);
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}
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}
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BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
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return pte;
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}
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pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd = NULL;
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pgd = pgd_offset(mm, addr);
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if (pgd_present(*pgd)) {
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pud = pud_offset(pgd, addr);
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if (pud_present(*pud)) {
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if (pud_large(*pud))
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return (pte_t *)pud;
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pmd = pmd_offset(pud, addr);
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}
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}
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return (pte_t *) pmd;
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}
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#if 0 /* This is just for testing */
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struct page *
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follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
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{
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unsigned long start = address;
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int length = 1;
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int nr;
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struct page *page;
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struct vm_area_struct *vma;
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vma = find_vma(mm, addr);
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if (!vma || !is_vm_hugetlb_page(vma))
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return ERR_PTR(-EINVAL);
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pte = huge_pte_offset(mm, address);
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/* hugetlb should be locked, and hence, prefaulted */
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WARN_ON(!pte || pte_none(*pte));
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page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
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WARN_ON(!PageHead(page));
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return page;
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}
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int pmd_huge(pmd_t pmd)
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{
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return 0;
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}
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int pud_huge(pud_t pud)
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{
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return 0;
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}
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struct page *
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follow_huge_pmd(struct mm_struct *mm, unsigned long address,
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pmd_t *pmd, int write)
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{
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return NULL;
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}
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#else
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struct page *
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follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
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{
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return ERR_PTR(-EINVAL);
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}
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int pmd_huge(pmd_t pmd)
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{
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return !!(pmd_val(pmd) & _PAGE_PSE);
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}
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int pud_huge(pud_t pud)
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{
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return !!(pud_val(pud) & _PAGE_PSE);
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}
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struct page *
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follow_huge_pmd(struct mm_struct *mm, unsigned long address,
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pmd_t *pmd, int write)
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{
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struct page *page;
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page = pte_page(*(pte_t *)pmd);
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if (page)
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page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
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return page;
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}
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struct page *
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follow_huge_pud(struct mm_struct *mm, unsigned long address,
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pud_t *pud, int write)
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{
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struct page *page;
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page = pte_page(*(pte_t *)pud);
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if (page)
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page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
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return page;
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}
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#endif
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/* x86_64 also uses this file */
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#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
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static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
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unsigned long addr, unsigned long len,
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unsigned long pgoff, unsigned long flags)
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{
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struct hstate *h = hstate_file(file);
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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unsigned long start_addr;
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if (len > mm->cached_hole_size) {
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start_addr = mm->free_area_cache;
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} else {
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start_addr = TASK_UNMAPPED_BASE;
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mm->cached_hole_size = 0;
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}
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full_search:
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addr = ALIGN(start_addr, huge_page_size(h));
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for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
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/* At this point: (!vma || addr < vma->vm_end). */
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if (TASK_SIZE - len < addr) {
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/*
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* Start a new search - just in case we missed
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* some holes.
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*/
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if (start_addr != TASK_UNMAPPED_BASE) {
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start_addr = TASK_UNMAPPED_BASE;
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mm->cached_hole_size = 0;
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goto full_search;
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}
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return -ENOMEM;
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}
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if (!vma || addr + len <= vma->vm_start) {
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mm->free_area_cache = addr + len;
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return addr;
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}
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if (addr + mm->cached_hole_size < vma->vm_start)
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mm->cached_hole_size = vma->vm_start - addr;
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addr = ALIGN(vma->vm_end, huge_page_size(h));
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}
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}
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static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
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unsigned long addr0, unsigned long len,
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unsigned long pgoff, unsigned long flags)
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{
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struct hstate *h = hstate_file(file);
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma, *prev_vma;
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unsigned long base = mm->mmap_base, addr = addr0;
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unsigned long largest_hole = mm->cached_hole_size;
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int first_time = 1;
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/* don't allow allocations above current base */
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if (mm->free_area_cache > base)
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mm->free_area_cache = base;
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if (len <= largest_hole) {
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largest_hole = 0;
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mm->free_area_cache = base;
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}
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try_again:
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/* make sure it can fit in the remaining address space */
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if (mm->free_area_cache < len)
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goto fail;
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/* either no address requested or cant fit in requested address hole */
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addr = (mm->free_area_cache - len) & huge_page_mask(h);
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do {
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/*
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* Lookup failure means no vma is above this address,
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* i.e. return with success:
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*/
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if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
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return addr;
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/*
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* new region fits between prev_vma->vm_end and
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* vma->vm_start, use it:
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*/
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if (addr + len <= vma->vm_start &&
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(!prev_vma || (addr >= prev_vma->vm_end))) {
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/* remember the address as a hint for next time */
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mm->cached_hole_size = largest_hole;
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return (mm->free_area_cache = addr);
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} else {
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/* pull free_area_cache down to the first hole */
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if (mm->free_area_cache == vma->vm_end) {
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mm->free_area_cache = vma->vm_start;
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mm->cached_hole_size = largest_hole;
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}
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}
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/* remember the largest hole we saw so far */
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if (addr + largest_hole < vma->vm_start)
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largest_hole = vma->vm_start - addr;
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/* try just below the current vma->vm_start */
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addr = (vma->vm_start - len) & huge_page_mask(h);
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} while (len <= vma->vm_start);
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fail:
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/*
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* if hint left us with no space for the requested
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* mapping then try again:
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*/
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if (first_time) {
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mm->free_area_cache = base;
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largest_hole = 0;
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first_time = 0;
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goto try_again;
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}
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/*
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* A failed mmap() very likely causes application failure,
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* so fall back to the bottom-up function here. This scenario
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* can happen with large stack limits and large mmap()
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* allocations.
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*/
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mm->free_area_cache = TASK_UNMAPPED_BASE;
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mm->cached_hole_size = ~0UL;
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addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
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len, pgoff, flags);
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/*
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* Restore the topdown base:
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*/
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mm->free_area_cache = base;
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mm->cached_hole_size = ~0UL;
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return addr;
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}
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unsigned long
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hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
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unsigned long len, unsigned long pgoff, unsigned long flags)
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{
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struct hstate *h = hstate_file(file);
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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if (len & ~huge_page_mask(h))
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return -EINVAL;
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if (len > TASK_SIZE)
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return -ENOMEM;
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if (flags & MAP_FIXED) {
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if (prepare_hugepage_range(file, addr, len))
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return -EINVAL;
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return addr;
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}
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if (addr) {
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addr = ALIGN(addr, huge_page_size(h));
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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(!vma || addr + len <= vma->vm_start))
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return addr;
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}
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if (mm->get_unmapped_area == arch_get_unmapped_area)
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return hugetlb_get_unmapped_area_bottomup(file, addr, len,
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pgoff, flags);
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else
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return hugetlb_get_unmapped_area_topdown(file, addr, len,
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pgoff, flags);
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}
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#endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
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#ifdef CONFIG_X86_64
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static __init int setup_hugepagesz(char *opt)
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{
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unsigned long ps = memparse(opt, &opt);
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if (ps == PMD_SIZE) {
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hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
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} else if (ps == PUD_SIZE && cpu_has_gbpages) {
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hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
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} else {
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printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n",
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ps >> 20);
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return 0;
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}
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return 1;
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}
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__setup("hugepagesz=", setup_hugepagesz);
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#endif
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