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Commit cfe28c5d authored by Steve Capper's avatar Steve Capper
Browse files

x86: mm: Remove x86 version of huge_pmd_share. 



The huge_pmd_share code has been copied over to mm/hugetlb.c to
make it accessible to other architectures.

Remove the x86 copy of the huge_pmd_share code and enable the
ARCH_WANT_HUGE_PMD_SHARE config flag. That way we reference the
general one.

Signed-off-by: default avatarSteve Capper <steve.capper@linaro.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3212b535

arch/x86/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -207,6 +207,9 @@ config ARCH_HIBERNATION_POSSIBLE 
config ARCH_SUSPEND_POSSIBLE

	def_bool y



config ARCH_WANT_HUGE_PMD_SHARE

	def_bool y



config ZONE_DMA32

	bool

	default X86_64

arch/x86/mm/hugetlbpage.c

+0 −120
Original line number Diff line number Diff line
@@ -16,126 +16,6 @@ 
#include <asm/tlbflush.h>

#include <asm/pgalloc.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;



	/* Allow segments to share if only one is marked locked */

	unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;

	unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;



	/*

	 * match the virtual addresses, permission and the alignment of the

	 * page table page.

	 */

	if (pmd_index(addr) != pmd_index(saddr) ||

	    vm_flags != svm_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. In any case calls pmd_alloc()

 * and returns the corresponding pte. While this is not necessary for the

 * !shared pmd case because we can allocate the pmd later as well, it makes the

 * code much cleaner. pmd allocation is essential for the shared case because

 * pud has to be populated inside the same i_mmap_mutex section - otherwise

 * racing tasks could either miss the sharing (see huge_pte_offset) or select a

 * bad pmd for sharing.

 */

static pte_t *

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 vm_area_struct *svma;

	unsigned long saddr;

	pte_t *spte = NULL;

	pte_t *pte;



	if (!vma_shareable(vma, addr))

		return (pte_t *)pmd_alloc(mm, pud, addr);



	mutex_lock(&mapping->i_mmap_mutex);

	vma_interval_tree_foreach(svma, &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, (pmd_t *)((unsigned long)spte & PAGE_MASK));

	else

		put_page(virt_to_page(spte));

	spin_unlock(&mm->page_table_lock);

out:

	pte = (pte_t *)pmd_alloc(mm, pud, addr);

	mutex_unlock(&mapping->i_mmap_mutex);

	return pte;

}



/*

 * 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, unsigned long sz)

{