![Michel Lespinasse](/assets/img/avatar_default.png)
Update the i386 hugetlb_get_unmapped_area function to make use of vm_unmapped_area() instead of implementing a brute force search. [akpm@linux-foundation.org: fix build] Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
374 lines
8.7 KiB
C
374 lines
8.7 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. In any case calls pmd_alloc()
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* and returns the corresponding pte. While this is not necessary for the
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* !shared pmd case because we can allocate the pmd later as well, it makes the
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* code much cleaner. pmd allocation is essential for the shared case because
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* pud has to be populated inside the same i_mmap_mutex section - otherwise
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* racing tasks could either miss the sharing (see huge_pte_offset) or select a
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* bad pmd for sharing.
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*/
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static pte_t *
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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 vm_area_struct *svma;
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unsigned long saddr;
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pte_t *spte = NULL;
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pte_t *pte;
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if (!vma_shareable(vma, addr))
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return (pte_t *)pmd_alloc(mm, pud, addr);
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mutex_lock(&mapping->i_mmap_mutex);
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vma_interval_tree_foreach(svma, &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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pte = (pte_t *)pmd_alloc(mm, pud, addr);
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mutex_unlock(&mapping->i_mmap_mutex);
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return pte;
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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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pte = huge_pmd_share(mm, addr, pud);
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else
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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 vm_unmapped_area_info info;
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info.flags = 0;
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info.length = len;
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info.low_limit = TASK_UNMAPPED_BASE;
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info.high_limit = TASK_SIZE;
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info.align_mask = PAGE_MASK & ~huge_page_mask(h);
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info.align_offset = 0;
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return vm_unmapped_area(&info);
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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 vm_unmapped_area_info info;
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unsigned long addr;
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info.flags = VM_UNMAPPED_AREA_TOPDOWN;
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info.length = len;
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info.low_limit = PAGE_SIZE;
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info.high_limit = current->mm->mmap_base;
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info.align_mask = PAGE_MASK & ~huge_page_mask(h);
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info.align_offset = 0;
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addr = vm_unmapped_area(&info);
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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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if (addr & ~PAGE_MASK) {
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VM_BUG_ON(addr != -ENOMEM);
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info.flags = 0;
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info.low_limit = TASK_UNMAPPED_BASE;
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info.high_limit = TASK_SIZE;
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addr = vm_unmapped_area(&info);
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}
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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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