arm64: Do not flush the D-cache for anonymous pages

[cascardo/linux.git] / arch / arm64 / mm / flush.c

diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
index 88611c3..7c71663 100644 (file)
--- a/arch/arm64/mm/flush.c
+++ b/arch/arm64/mm/flush.c
@@ -77,14 +77,12 @@ void __flush_dcache_page(struct page *page)
 
 void __sync_icache_dcache(pte_t pte, unsigned long addr)
 {
-       unsigned long pfn;
-       struct page *page;
+       struct page *page = pte_page(pte);
 
-       pfn = pte_pfn(pte);
-       if (!pfn_valid(pfn))
+       /* no flushing needed for anonymous pages */
+       if (!page_mapping(page))
                return;
 
-       page = pfn_to_page(pfn);
        if (!test_and_set_bit(PG_dcache_clean, &page->flags)) {
                __flush_dcache_page(page);
                __flush_icache_all();
@@ -94,28 +92,14 @@ void __sync_icache_dcache(pte_t pte, unsigned long addr)
 }
 
 /*
- * Ensure cache coherency between kernel mapping and userspace mapping of this
- * page.
+ * This function is called when a page has been modified by the kernel. Mark
+ * it as dirty for later flushing when mapped in user space (if executable,
+ * see __sync_icache_dcache).
  */
 void flush_dcache_page(struct page *page)
 {
-       struct address_space *mapping;
-
-       /*
-        * The zero page is never written to, so never has any dirty cache
-        * lines, and therefore never needs to be flushed.
-        */
-       if (page == ZERO_PAGE(0))
-               return;
-
-       mapping = page_mapping(page);
-       if (mapping && mapping_mapped(mapping)) {
-               __flush_dcache_page(page);
-               __flush_icache_all();
-               set_bit(PG_dcache_clean, &page->flags);
-       } else {
+       if (test_bit(PG_dcache_clean, &page->flags))
                clear_bit(PG_dcache_clean, &page->flags);
-       }
 }
 EXPORT_SYMBOL(flush_dcache_page);