From 2d42552d1c1659b014851cf449ad2fe458509128 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 23 May 2011 10:24:39 +0200 Subject: [PATCH] [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: Martin Schwidefsky --- arch/s390/include/asm/page.h | 56 +++++++++++++++++++++++++++---- arch/s390/include/asm/pgtable.h | 58 +++++---------------------------- include/asm-generic/pgtable.h | 12 +++---- include/linux/page-flags.h | 2 +- mm/rmap.c | 11 +++---- 5 files changed, 68 insertions(+), 71 deletions(-) diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h index 3c987e9ec8d6..81ee2776088d 100644 --- a/arch/s390/include/asm/page.h +++ b/arch/s390/include/asm/page.h @@ -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); diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 763620ec7925..4ca4dd2b329a 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -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 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. diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index b4bfe338ea0e..e9b8e5926bef 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -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 diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 811183de1ef5..79a6700b7162 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -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, diff --git a/mm/rmap.c b/mm/rmap.c index 8da044a1db0f..522e4a93cadd 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -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; @@ -785,10 +785,8 @@ 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; - } } } @@ -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. -- 2.20.1