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Commit 2d42552d authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] merge page_test_dirty and page_clear_dirty 



The page_clear_dirty primitive always sets the default storage key
which resets the access control bits and the fetch protection bit.
That will surprise a KVM guest that sets non-zero access control
bits or the fetch protection bit. Merge page_test_dirty and
page_clear_dirty back to a single function and only clear the
dirty bit from the storage key.

In addition move the function page_test_and_clear_dirty and
page_test_and_clear_young to page.h where they belong. This
requires to change the parameter from a struct page * to a page
frame number.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent c26001d4

arch/s390/include/asm/page.h

+50 −6
Original line number Diff line number Diff line
@@ -107,8 +107,8 @@ typedef pte_t *pgtable_t; 
#define __pgd(x)        ((pgd_t) { (x) } )

#define __pgprot(x)     ((pgprot_t) { (x) } )



static inline void

page_set_storage_key(unsigned long addr, unsigned int skey, int mapped)

static inline void page_set_storage_key(unsigned long addr,

					unsigned char skey, int mapped)

{

	if (!mapped)

		asm volatile(".insn rrf,0xb22b0000,%0,%1,8,0"
@@ -117,15 +117,59 @@ page_set_storage_key(unsigned long addr, unsigned int skey, int mapped) 
		asm volatile("sske %0,%1" : : "d" (skey), "a" (addr));

}



static inline unsigned int

page_get_storage_key(unsigned long addr)

static inline unsigned char page_get_storage_key(unsigned long addr)

{

	unsigned int skey;

	unsigned char skey;



	asm volatile("iske %0,%1" : "=d" (skey) : "a" (addr), "0" (0));

	asm volatile("iske %0,%1" : "=d" (skey) : "a" (addr));

	return skey;

}



static inline int page_reset_referenced(unsigned long addr)

{

	unsigned int ipm;



	asm volatile(

		"	rrbe	0,%1\n"

		"	ipm	%0\n"

		: "=d" (ipm) : "a" (addr) : "cc");

	return !!(ipm & 0x20000000);

}



/* Bits int the storage key */

#define _PAGE_CHANGED		0x02	/* HW changed bit		*/

#define _PAGE_REFERENCED	0x04	/* HW referenced bit		*/

#define _PAGE_FP_BIT		0x08	/* HW fetch protection bit	*/

#define _PAGE_ACC_BITS		0xf0	/* HW access control bits	*/



/*

 * Test and clear dirty bit in storage key.

 * We can't clear the changed bit atomically. This is a potential

 * race against modification of the referenced bit. This function

 * should therefore only be called if it is not mapped in any

 * address space.

 */

#define __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY

static inline int page_test_and_clear_dirty(unsigned long pfn, int mapped)

{

	unsigned char skey;



	skey = page_get_storage_key(pfn << PAGE_SHIFT);

	if (!(skey & _PAGE_CHANGED))

		return 0;

	page_set_storage_key(pfn << PAGE_SHIFT, skey & ~_PAGE_CHANGED, mapped);

	return 1;

}



/*

 * Test and clear referenced bit in storage key.

 */

#define __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG

static inline int page_test_and_clear_young(unsigned long pfn)

{

	return page_reset_referenced(pfn << PAGE_SHIFT);

}



struct page;

void arch_free_page(struct page *page, int order);

void arch_alloc_page(struct page *page, int order);

arch/s390/include/asm/pgtable.h

+9 −49
Original line number Diff line number Diff line
@@ -373,10 +373,6 @@ extern unsigned long VMALLOC_START; 
#define _ASCE_USER_BITS		(_ASCE_SPACE_SWITCH | _ASCE_PRIVATE_SPACE | \

				 _ASCE_ALT_EVENT)



/* Bits int the storage key */

#define _PAGE_CHANGED    0x02          /* HW changed bit                   */

#define _PAGE_REFERENCED 0x04          /* HW referenced bit                */



/*

 * Page protection definitions.

 */
@@ -555,8 +551,6 @@ static inline void rcp_unlock(pte_t *ptep) 
#endif

}



/* forward declaration for SetPageUptodate in page-flags.h*/

static inline void page_clear_dirty(struct page *page, int mapped);

#include <linux/page-flags.h>



static inline void ptep_rcp_copy(pte_t *ptep)
@@ -566,7 +560,7 @@ static inline void ptep_rcp_copy(pte_t *ptep) 
	unsigned int skey;

	unsigned long *pgste = (unsigned long *) (ptep + PTRS_PER_PTE);



	skey = page_get_storage_key(page_to_phys(page));

	skey = page_get_storage_key(pte_val(*ptep) >> PAGE_SHIFT);

	if (skey & _PAGE_CHANGED) {

		set_bit_simple(RCP_GC_BIT, pgste);

		set_bit_simple(KVM_UD_BIT, pgste);
@@ -760,6 +754,7 @@ static inline int kvm_s390_test_and_clear_page_dirty(struct mm_struct *mm, 
{

	int dirty;

	unsigned long *pgste;

	unsigned long pfn;

	struct page *page;

	unsigned int skey;
@@ -767,8 +762,9 @@ static inline int kvm_s390_test_and_clear_page_dirty(struct mm_struct *mm, 
		return -EINVAL;

	rcp_lock(ptep);

	pgste = (unsigned long *) (ptep + PTRS_PER_PTE);

	page = virt_to_page(pte_val(*ptep));

	skey = page_get_storage_key(page_to_phys(page));

	pfn = pte_val(*ptep) >> PAGE_SHIFT;

	page = pfn_to_page(pfn);

	skey = page_get_storage_key(pfn);

	if (skey & _PAGE_CHANGED) {

		set_bit_simple(RCP_GC_BIT, pgste);

		set_bit_simple(KVM_UD_BIT, pgste);
@@ -779,7 +775,7 @@ static inline int kvm_s390_test_and_clear_page_dirty(struct mm_struct *mm, 
	}

	dirty = test_and_clear_bit_simple(KVM_UD_BIT, pgste);

	if (skey & _PAGE_CHANGED)

		page_clear_dirty(page, 1);

		page_set_storage_key(pfn, skey & ~_PAGE_CHANGED, 1);

	rcp_unlock(ptep);

	return dirty;

}
@@ -790,16 +786,16 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, 
					    unsigned long addr, pte_t *ptep)

{

#ifdef CONFIG_PGSTE

	unsigned long physpage;

	unsigned long pfn;

	int young;

	unsigned long *pgste;



	if (!vma->vm_mm->context.has_pgste)

		return 0;

	physpage = pte_val(*ptep) & PAGE_MASK;

	pfn = pte_val(*ptep) >> PAGE_SHIFT;

	pgste = (unsigned long *) (ptep + PTRS_PER_PTE);



	young = ((page_get_storage_key(physpage) & _PAGE_REFERENCED) != 0);

	young = ((page_get_storage_key(pfn) & _PAGE_REFERENCED) != 0);

	rcp_lock(ptep);

	if (young)

		set_bit_simple(RCP_GR_BIT, pgste);
@@ -936,42 +932,6 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, 
	__changed;							\

})



/*

 * Test and clear dirty bit in storage key.

 * We can't clear the changed bit atomically. This is a potential

 * race against modification of the referenced bit. This function

 * should therefore only be called if it is not mapped in any

 * address space.

 */

#define __HAVE_ARCH_PAGE_TEST_DIRTY

static inline int page_test_dirty(struct page *page)

{

	return (page_get_storage_key(page_to_phys(page)) & _PAGE_CHANGED) != 0;

}



#define __HAVE_ARCH_PAGE_CLEAR_DIRTY

static inline void page_clear_dirty(struct page *page, int mapped)

{

	page_set_storage_key(page_to_phys(page), PAGE_DEFAULT_KEY, mapped);

}



/*

 * Test and clear referenced bit in storage key.

 */

#define __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG

static inline int page_test_and_clear_young(struct page *page)

{

	unsigned long physpage = page_to_phys(page);

	int ccode;



	asm volatile(

		"	rrbe	0,%1\n"

		"	ipm	%0\n"

		"	srl	%0,28\n"

		: "=d" (ccode) : "a" (physpage) : "cc" );

	return ccode & 2;

}



/*

 * Conversion functions: convert a page and protection to a page entry,

 * and a page entry and page directory to the page they refer to.

include/asm-generic/pgtable.h

+4 −8
Original line number Diff line number Diff line
@@ -184,22 +184,18 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b) 
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

#endif



#ifndef __HAVE_ARCH_PAGE_TEST_DIRTY

#define page_test_dirty(page)		(0)

#ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY

#define page_test_and_clear_dirty(pfn, mapped)	(0)

#endif



#ifndef __HAVE_ARCH_PAGE_CLEAR_DIRTY

#define page_clear_dirty(page, mapped)	do { } while (0)

#endif



#ifndef __HAVE_ARCH_PAGE_TEST_DIRTY

#ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY

#define pte_maybe_dirty(pte)		pte_dirty(pte)

#else

#define pte_maybe_dirty(pte)		(1)

#endif



#ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG

#define page_test_and_clear_young(page) (0)

#define page_test_and_clear_young(pfn) (0)

#endif



#ifndef __HAVE_ARCH_PGD_OFFSET_GATE

include/linux/page-flags.h

+1 −1
Original line number Diff line number Diff line
@@ -308,7 +308,7 @@ static inline void SetPageUptodate(struct page *page) 
{

#ifdef CONFIG_S390

	if (!test_and_set_bit(PG_uptodate, &page->flags))

		page_clear_dirty(page, 0);

		page_set_storage_key(page_to_pfn(page), PAGE_DEFAULT_KEY, 0);

#else

	/*

	 * Memory barrier must be issued before setting the PG_uptodate bit,

mm/rmap.c

+4 −7
Original line number Diff line number Diff line
@@ -719,7 +719,7 @@ int page_referenced(struct page *page, 
			unlock_page(page);

	}

out:

	if (page_test_and_clear_young(page))

	if (page_test_and_clear_young(page_to_pfn(page)))

		referenced++;



	return referenced;
@@ -785,12 +785,10 @@ int page_mkclean(struct page *page) 
		struct address_space *mapping = page_mapping(page);

		if (mapping) {

			ret = page_mkclean_file(mapping, page);

			if (page_test_dirty(page)) {

				page_clear_dirty(page, 1);

			if (page_test_and_clear_dirty(page_to_pfn(page), 1))

				ret = 1;

		}

	}

	}



	return ret;

}
@@ -981,10 +979,9 @@ void page_remove_rmap(struct page *page) 
	 * not if it's in swapcache - there might be another pte slot

	 * containing the swap entry, but page not yet written to swap.

	 */

	if ((!PageAnon(page) || PageSwapCache(page)) && page_test_dirty(page)) {

		page_clear_dirty(page, 1);

	if ((!PageAnon(page) || PageSwapCache(page)) &&

	    page_test_and_clear_dirty(page_to_pfn(page), 1))

		set_page_dirty(page);

	}

	/*

	 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED

	 * and not charged by memcg for now.