Commit bb5c2dbd authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86: further cpa largepage-split cleanups 



further cpa largepage-split cleanups: make the splitup isolated
functionality, without leaking details back into __change_page_attr().

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 97f99fed

arch/x86/mm/pageattr_32.c

+49 −40
Original line number Diff line number Diff line
@@ -37,33 +37,6 @@ 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)

{

	unsigned long addr;

	struct page *base;

	pte_t *pbase;

	int i;



	base = alloc_pages(GFP_KERNEL, 0);

	if (!base)

		return NULL;



	/*

	 * page_private is used to track the number of entries in

	 * the page table page that have non standard attributes.

	 */

	address = __pa(address);

	addr = address & LARGE_PAGE_MASK;

	pbase = (pte_t *)page_address(base);

	paravirt_alloc_pt(&init_mm, page_to_pfn(base));



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

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



	return base;

}



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

{

	unsigned long flags;
@@ -88,14 +61,58 @@ static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) 
	spin_unlock_irqrestore(&pgd_lock, flags);

}



static int

split_large_page(pte_t *kpte, unsigned long address, pgprot_t ref_prot)

{

	int i, level;

	unsigned long addr;

	pte_t *pbase, *tmp;

	struct page *base;



	base = alloc_pages(GFP_KERNEL, 0);

	if (!base)

		return -ENOMEM;



	down_write(&init_mm.mmap_sem);

	/*

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

	 * up for us already:

	 */

	tmp = lookup_address(address, &level);

	if (tmp != kpte)

		goto out_unlock;



	address = __pa(address);

	addr = address & LARGE_PAGE_MASK;

	pbase = (pte_t *)page_address(base);

	paravirt_alloc_pt(&init_mm, page_to_pfn(base));



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

		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:

	up_write(&init_mm.mmap_sem);



	if (base)

		__free_pages(base, 0);



	return 0;

}



static int __change_page_attr(struct page *page, pgprot_t prot)

{

	pgprot_t ref_prot = PAGE_KERNEL;

	struct page *kpte_page;

	unsigned long address;

	int level, err = 0;

	pgprot_t oldprot;

	pte_t *kpte;

	int level;



	BUG_ON(PageHighMem(page));

	address = (unsigned long)page_address(page);
@@ -127,19 +144,11 @@ static int __change_page_attr(struct page *page, pgprot_t prot) 
	if (level == 3) {

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

	} else {

		struct page *split;



		split = split_large_page(address, ref_prot);

		if (!split)

			return -ENOMEM;



		/*

		 * There's a small window here to waste a bit of RAM:

		 */

		set_pmd_pte(kpte, address, mk_pte(split, ref_prot));

		err = split_large_page(kpte, address, ref_prot);

		if (!err)

			goto repeat;

	}

	return 0;

	return err;

}



/*