[PATCH] ARM: Fix delayed dcache flush for ARMv6 non-aliasing caches

flush_dcache_page() did nothing for these caches, but since they
suffer from I/D cache coherency issues, we need to ensure that data
is written back to RAM.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 29 insertions, 46 deletions

diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index 01967ddeef53..be4ab3d73c91 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -77,9 +77,8 @@ no_pmd:
 }
 
 static void
-make_coherent(struct vm_area_struct *vma, unsigned long addr, struct page *page, int dirty)
+make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigned long addr, unsigned long pfn)
 {
-        struct address_space *mapping = page_mapping(page);
         struct mm_struct *mm = vma->vm_mm;
         struct vm_area_struct *mpnt;
         struct prio_tree_iter iter;
@@ -87,9 +86,6 @@ make_coherent(struct vm_area_struct *vma, unsigned long addr, struct page *page,
         pgoff_t pgoff;
         int aliases = 0;
 
-        if (!mapping)
-                return;
-
         pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);
 
         /*
@@ -115,9 +111,11 @@ make_coherent(struct vm_area_struct *vma, unsigned long addr, struct page *page,
         if (aliases)
                 adjust_pte(vma, addr);
         else
-                flush_cache_page(vma, addr, page_to_pfn(page));
+                flush_cache_page(vma, addr, pfn);
 }
 
+void __flush_dcache_page(struct address_space *mapping, struct page *page);
+
 /*
  * Take care of architecture specific things when placing a new PTE into
  * a page table, or changing an existing PTE.  Basically, there are two
@@ -134,29 +132,22 @@ make_coherent(struct vm_area_struct *vma, unsigned long addr, struct page *page,
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
 {
         unsigned long pfn = pte_pfn(pte);
+        struct address_space *mapping;
         struct page *page;
 
         if (!pfn_valid(pfn))
                 return;
+
         page = pfn_to_page(pfn);
-        if (page_mapping(page)) {
+        mapping = page_mapping(page);
+        if (mapping) {
                 int dirty = test_and_clear_bit(PG_dcache_dirty, &page->flags);
 
-                if (dirty) {
-                        /*
-                         * This is our first userspace mapping of this page.
-                         * Ensure that the physical page is coherent with
-                         * the kernel mapping.
-                         *
-                         * FIXME: only need to do this on VIVT and aliasing
-                         *        VIPT cache architectures.  We can do that
-                         *        by choosing whether to set this bit...
-                         */
-                        __cpuc_flush_dcache_page(page_address(page));
-                }
+                if (dirty)
+                        __flush_dcache_page(mapping, page);
 
                 if (cache_is_vivt())
-                        make_coherent(vma, addr, page, dirty);
+                        make_coherent(mapping, vma, addr, pfn);
         }
 }
 
diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 4085ed983e46..191788fb18d1 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -37,13 +37,8 @@ static void flush_pfn_alias(unsigned long pfn, unsigned long vaddr)
 #define flush_pfn_alias(pfn,vaddr)      do { } while (0)
 #endif
 
-static void __flush_dcache_page(struct address_space *mapping, struct page *page)
+void __flush_dcache_page(struct address_space *mapping, struct page *page)
 {
-        struct mm_struct *mm = current->active_mm;
-        struct vm_area_struct *mpnt;
-        struct prio_tree_iter iter;
-        pgoff_t pgoff;
-
         /*
          * Writeback any data associated with the kernel mapping of this
          * page.  This ensures that data in the physical page is mutually
@@ -52,24 +47,21 @@ static void __flush_dcache_page(struct address_space *mapping, struct page *page
         __cpuc_flush_dcache_page(page_address(page));
 
         /*
-         * If there's no mapping pointer here, then this page isn't
-         * visible to userspace yet, so there are no cache lines
-         * associated with any other aliases.
-         */
-        if (!mapping)
-                return;
-
-        /*
-         * This is a page cache page.  If we have a VIPT cache, we
-         * only need to do one flush - which would be at the relevant
+         * If this is a page cache page, and we have an aliasing VIPT cache,
+         * we only need to do one flush - which would be at the relevant
          * userspace colour, which is congruent with page->index.
          */
-        if (cache_is_vipt()) {
-                if (cache_is_vipt_aliasing())
-                        flush_pfn_alias(page_to_pfn(page),
-                                        page->index << PAGE_CACHE_SHIFT);
-                return;
-        }
+        if (mapping && cache_is_vipt_aliasing())
+                flush_pfn_alias(page_to_pfn(page),
+                                page->index << PAGE_CACHE_SHIFT);
+}
+
+static void __flush_dcache_aliases(struct address_space *mapping, struct page *page)
+{
+        struct mm_struct *mm = current->active_mm;
+        struct vm_area_struct *mpnt;
+        struct prio_tree_iter iter;
+        pgoff_t pgoff;
 
         /*
          * There are possible user space mappings of this page:
@@ -116,12 +108,12 @@ void flush_dcache_page(struct page *page)
 {
         struct address_space *mapping = page_mapping(page);
 
-        if (cache_is_vipt_nonaliasing())
-                return;
-
         if (mapping && !mapping_mapped(mapping))
                 set_bit(PG_dcache_dirty, &page->flags);
-        else
+        else {
                 __flush_dcache_page(mapping, page);
+                if (mapping && cache_is_vivt())
+                        __flush_dcache_aliases(mapping, page);
+        }
 }
 EXPORT_SYMBOL(flush_dcache_page);