[ARM] 4078/1: Fix ARM copypage cache coherency problems

If PG_dcache_dirty is set for a page, we need to flush the source page
before performing any copypage operation using a different virtual address.

This fixes the copypage implementations for XScale, StrongARM and ARMv6.

This patch fixes segmentation faults seen in the dynamic linker under
the usage patterns in glibc 2.4/2.5.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/copypage-v4mc.c

@@ -19,6 +19,7 @@
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
+#include <asm/cacheflush.h>
 
 #include "mm.h"
 
@@ -69,6 +70,11 @@ mc_copy_user_page(void *from, void *to)
 
 void v4_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
 {
+	struct page *page = virt_to_page(kfrom);
+
+	if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
+		__flush_dcache_page(page_mapping(page), page);
+
 	spin_lock(&minicache_lock);
 
 	set_pte_ext(TOP_PTE(0xffff8000), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot), 0);

arch/arm/mm/copypage-v6.c

@@ -53,6 +53,10 @@ static void v6_copy_user_page_aliasing(void *kto, const void *kfrom, unsigned lo
 {
 	unsigned int offset = CACHE_COLOUR(vaddr);
 	unsigned long from, to;
+	struct page *page = virt_to_page(kfrom);
+
+	if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
+		__flush_dcache_page(page_mapping(page), page);
 
 	/*
 	 * Discard data in the kernel mapping for the new page.

arch/arm/mm/copypage-xscale.c

@@ -19,6 +19,7 @@
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
+#include <asm/cacheflush.h>
 
 #include "mm.h"
 
@@ -91,6 +92,11 @@ mc_copy_user_page(void *from, void *to)
 
 void xscale_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
 {
+	struct page *page = virt_to_page(kfrom);
+
+	if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
+		__flush_dcache_page(page_mapping(page), page);
+
 	spin_lock(&minicache_lock);
 
 	set_pte_ext(TOP_PTE(COPYPAGE_MINICACHE), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot), 0);

include/asm-arm/cacheflush.h

@@ -355,6 +355,8 @@ extern void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
  */
 extern void flush_dcache_page(struct page *);
 
+extern void __flush_dcache_page(struct address_space *mapping, struct page *page);
+
 #define flush_dcache_mmap_lock(mapping) \
 	write_lock_irq(&(mapping)->tree_lock)
 #define flush_dcache_mmap_unlock(mapping) \