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Commit 6faa4c53 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86: 64-bit, add the new split_large_page() function 



Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 44136717

arch/x86/mm/pageattr_64.c

+71 −24
Original line number Diff line number Diff line
@@ -45,34 +45,91 @@ pte_t *lookup_address(unsigned long address, int *level) 
	return pte_offset_kernel(pmd, address);

}



static struct page *

split_large_page(unsigned long address, pgprot_t ref_prot)

static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)

{

	/* change init_mm */

	set_pte_atomic(kpte, pte);

#ifdef CONFIG_X86_32

	if (SHARED_KERNEL_PMD)

		return;

	{

		struct page *page;



		for (page = pgd_list; page; page = (struct page *)page->index) {

			pgd_t *pgd;

			pud_t *pud;

			pmd_t *pmd;



			pgd = (pgd_t *)page_address(page) + pgd_index(address);

			pud = pud_offset(pgd, address);

			pmd = pmd_offset(pud, address);

			set_pte_atomic((pte_t *)pmd, pte);

		}

	}

#endif

}



static int split_large_page(pte_t *kpte, unsigned long address)

{

	pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));

	gfp_t gfp_flags = GFP_KERNEL;

	unsigned long flags;

	unsigned long addr;

	pte_t *pbase, *tmp;

	struct page *base;

	pte_t *pbase;

	int i;

	int i, level;





	base = alloc_pages(GFP_KERNEL, 0);

#ifdef CONFIG_DEBUG_PAGEALLOC

	gfp_flags = GFP_ATOMIC;

#endif

	base = alloc_pages(gfp_flags, 0);

	if (!base)

		return NULL;

		return -ENOMEM;



	spin_lock_irqsave(&pgd_lock, flags);

	/*

	 * Check for races, another CPU might have split this page

	 * up for us already:

	 */

	tmp = lookup_address(address, &level);

	if (tmp != kpte) {

		WARN_ON_ONCE(1);

		goto out_unlock;

	}



	address = __pa(address);

	addr = address & LARGE_PAGE_MASK;

	pbase = (pte_t *)page_address(base);

#ifdef CONFIG_X86_32

	paravirt_alloc_pt(&init_mm, page_to_pfn(base));

#endif



	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)

		pbase[i] = pfn_pte(addr >> PAGE_SHIFT, ref_prot);

		set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));



	/*

	 * Install the new, split up pagetable:

	 */

	__set_pmd_pte(kpte, address, mk_pte(base, ref_prot));

	base = NULL;



out_unlock:

	spin_unlock_irqrestore(&pgd_lock, flags);



	if (base)

		__free_pages(base, 0);



	return base;

	return 0;

}



static int

__change_page_attr(unsigned long address, struct page *page, pgprot_t prot)

{

	pgprot_t ref_prot2, oldprot;

	struct page *kpte_page;

	int level, err = 0;

	pte_t *kpte;

	pgprot_t ref_prot2, oldprot;

	int level;



repeat:

	kpte = lookup_address(address, &level);
@@ -88,22 +145,12 @@ __change_page_attr(unsigned long address, struct page *page, pgprot_t prot) 
	if (level == 4) {

		set_pte_atomic(kpte, mk_pte(page, prot));

	} else {

		/*

		 * split_large_page will take the reference for this

		 * change_page_attr on the split page.

		 */

		struct page *split;



		ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));

		split = split_large_page(address, ref_prot2);

		if (!split)

			return -ENOMEM;

		pgprot_val(ref_prot2) &= ~_PAGE_NX;

		set_pte_atomic(kpte, mk_pte(split, ref_prot2));

		err = split_large_page(kpte, address);

		if (!err)

			goto repeat;

	}



	return 0;

	return err;

}



/**