[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 <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index 3c987e9..81ee277 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -107,8 +107,8 @@
#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 @@
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);