parisc: fixes and cleanups in page cache flushing (1/4)

This is the first patch in a series of 4, with which the page cache flushing of
parisc will gets fixed and enhanced. This even fixes the nasty "minifail" bug
(http://wiki.parisc-linux.org/TestCases?highlight=%28minifail%29) which
prevented parisc to stay an official debian port.  Basically the flush in
copy_user_page together with the TLB patch from commit
7139bc1579901b53db7e898789e916ee2fb52d78 is what fixes the minifail bug.

This patch still uses the TMPALIAS approach.  The new copy_user_page
implementation calls flush_dcache_page_asm to flush the user dcache page
(crucial for minifail fix) via a kernel TMPALIAS mapping.  After that, it just
copies the page using the kernel mapping.  It does a final flush if needed.
Generally it is hard to avoid doing some cache flushes using the kernel mapping
(e.g., copy_to_user_page and copy_from_user_page).

This patch depends on a subsequent change to pacache.S implementing
clear_page_asm and copy_page_asm.  These are optimized routines to clear and
copy a page.  The calls in clear_user_page and copy_user_page could be replaced
by calls to memset and memcpy, respectively.  I tested prefetch optimizations
in clear_page_asm and copy_page_asm but didn't see any significant performance
improvement on rp3440.  I'm not sure if these are routines are significantly
faster than memset and/or memcpy, but they are there for further performance
evaluation.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>

1 files changed, 16 insertions, 4 deletions

diff --git a/arch/parisc/include/asm/page.h b/arch/parisc/include/asm/page.h
index 4e0e7dbf0f3f..b7adb2ac049c 100644
--- a/arch/parisc/include/asm/page.h
+++ b/arch/parisc/include/asm/page.h
@@ -21,15 +21,27 @@
 #include <asm/types.h>
 #include <asm/cache.h>
 
-#define clear_page(page)	memset((void *)(page), 0, PAGE_SIZE)
-#define copy_page(to,from)      copy_user_page_asm((void *)(to), (void *)(from))
+#define clear_page(page)	clear_page_asm((void *)(page))
+#define copy_page(to, from)	copy_page_asm((void *)(to), (void *)(from))
 
 struct page;
 
-void copy_user_page_asm(void *to, void *from);
+void clear_page_asm(void *page);
+void copy_page_asm(void *to, void *from);
+void clear_user_page(void *vto, unsigned long vaddr, struct page *pg);
 void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
 			   struct page *pg);
-void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
+
+/* #define CONFIG_PARISC_TMPALIAS */
+
+#ifdef CONFIG_PARISC_TMPALIAS
+void clear_user_highpage(struct page *page, unsigned long vaddr);
+#define clear_user_highpage clear_user_highpage
+struct vm_area_struct;
+void copy_user_highpage(struct page *to, struct page *from,
+	unsigned long vaddr, struct vm_area_struct *vma);
+#define __HAVE_ARCH_COPY_USER_HIGHPAGE
+#endif
 
 /*
  * These are used to make use of C type-checking..