parisc: Rewrite cache flush code for PA8800/PA8900

Originally, I was convinced that we needed to use tmpalias flushes
everwhere, for both user and kernel flushes. However, when I modified
flush_kernel_dcache_page_addr, to use a tmpalias flush, my c8000
would crash quite early when booting.

The PDC returns alias values of 0 for the icache and dcache. This
indicates that either the alias boundary is greater than 16MB or
equivalent aliasing doesn't work. I modified the tmpalias code to
make it easy to try alternate boundaries. I tried boundaries up to
128MB but still kernel tmpalias flushes didn't work on c8000.

This led me to conclude that tmpalias flushes don't work on PA8800
and PA8900 machines, and that we needed to flush directly using the
virtual address of user and kernel pages. This is likely the major
cause of instability on the c8000 and rp34xx machines.

Flushing user pages requires doing a temporary context switch as we
have to flush pages that don't belong to the current context. Further,
we have to deal with pages that aren't present. If a page isn't
present, the flush instructions fault on every line.

Other code has been rearranged and simplified based on testing. For
example, I introduced a flush_cache_dup_mm routine. flush_cache_mm
and flush_cache_dup_mm differ in that flush_cache_mm calls
purge_cache_pages and flush_cache_dup_mm calls flush_cache_pages.
In some implementations, pdc is more efficient than fdc. Based on
my testing, I don't believe there's any performance benefit on the
c8000.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/include/asm/cacheflush.h

@@ -59,20 +59,12 @@ void flush_dcache_page(struct page *page);
 	flush_kernel_icache_range_asm(s,e); 		\
 } while (0)
 
-#define copy_to_user_page(vma, page, vaddr, dst, src, len) \
-do { \
-	flush_cache_page(vma, vaddr, page_to_pfn(page)); \
-	memcpy(dst, src, len); \
-	flush_kernel_dcache_range_asm((unsigned long)dst, (unsigned long)dst + len); \
-} while (0)
-
-#define copy_from_user_page(vma, page, vaddr, dst, src, len) \
-do { \
-	flush_cache_page(vma, vaddr, page_to_pfn(page)); \
-	memcpy(dst, src, len); \
-} while (0)
-
-void flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long pfn);
+void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
+		unsigned long user_vaddr, void *dst, void *src, int len);
+void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
+		unsigned long user_vaddr, void *dst, void *src, int len);
+void flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr,
+		unsigned long pfn);
 void flush_cache_range(struct vm_area_struct *vma,
 		unsigned long start, unsigned long end);
 
@@ -80,16 +72,7 @@ void flush_cache_range(struct vm_area_struct *vma,
 void flush_dcache_page_asm(unsigned long phys_addr, unsigned long vaddr);
 
 #define ARCH_HAS_FLUSH_ANON_PAGE
-static inline void
-flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
-{
-	if (PageAnon(page)) {
-		flush_tlb_page(vma, vmaddr);
-		preempt_disable();
-		flush_dcache_page_asm(page_to_phys(page), vmaddr);
-		preempt_enable();
-	}
-}
+void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr);
 
 #define ARCH_HAS_FLUSH_ON_KUNMAP
 static inline void kunmap_flush_on_unmap(void *addr)

arch/parisc/include/asm/page.h

@@ -26,12 +26,14 @@
 #define copy_page(to, from)	copy_page_asm((void *)(to), (void *)(from))
 
 struct page;
+struct vm_area_struct;
 
 void clear_page_asm(void *page);
 void copy_page_asm(void *to, void *from);
 #define clear_user_page(vto, vaddr, page) clear_page_asm(vto)
-void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
-			struct page *pg);
+void copy_user_highpage(struct page *to, struct page *from, unsigned long vaddr,
+		struct vm_area_struct *vma);
+#define __HAVE_ARCH_COPY_USER_HIGHPAGE
 
 /*
  * These are used to make use of C type-checking..