[PATCH] ARM: Add V6 aliasing cache flush

Add cache flushing support for aliased V6 caches to
flush_dcache_page.

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

1 files changed, 35 insertions, 2 deletions

diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index c6de48d89503..4085ed983e46 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -13,6 +13,29 @@
 
 #include <asm/cacheflush.h>
 #include <asm/system.h>
+#include <asm/tlbflush.h>
+
+#ifdef CONFIG_CPU_CACHE_VIPT
+#define ALIAS_FLUSH_START       0xffff4000
+
+#define TOP_PTE(x)      pte_offset_kernel(top_pmd, x)
+
+static void flush_pfn_alias(unsigned long pfn, unsigned long vaddr)
+{
+        unsigned long to = ALIAS_FLUSH_START + (CACHE_COLOUR(vaddr) << PAGE_SHIFT);
+
+        set_pte(TOP_PTE(to), pfn_pte(pfn, PAGE_KERNEL));
+        flush_tlb_kernel_page(to);
+
+        asm(    "mcrr   p15, 0, %1, %0, c14\n"
+        "       mcrr    p15, 0, %1, %0, c5\n"
+            :
+            : "r" (to), "r" (to + PAGE_SIZE - L1_CACHE_BYTES)
+            : "cc");
+}
+#else
+#define flush_pfn_alias(pfn,vaddr)      do { } while (0)
+#endif
 
 static void __flush_dcache_page(struct address_space *mapping, struct page *page)
 {
@@ -37,6 +60,18 @@ static void __flush_dcache_page(struct address_space *mapping, struct page *page
                 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
+         * 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;
+        }
+
+        /*
          * There are possible user space mappings of this page:
          * - VIVT cache: we need to also write back and invalidate all user
          *   data in the current VM view associated with this page.
@@ -57,8 +92,6 @@ static void __flush_dcache_page(struct address_space *mapping, struct page *page
                         continue;
                 offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
                 flush_cache_page(mpnt, mpnt->vm_start + offset, page_to_pfn(page));
-                if (cache_is_vipt())
-                        break;
         }
         flush_dcache_mmap_unlock(mapping);
 }