[PARISC] prevent speculative re-read on cache flush

According to Appendix F, the TLB is the primary arbiter of speculation.
Thus, if a page has a TLB entry, it may be speculatively read into the
cache.  On linux, this can cause us incoherencies because if we're about
to do a disk read, we call get_user_pages() to do the flush/invalidate
in user space, but we still potentially have the user TLB entries, and
the cache could speculate the lines back into userspace (thus causing
stale data to be used).  This is fixed by purging the TLB entries before
we flush through the tmpalias space.  Now, the only way the line could
be re-speculated is if the user actually tries to touch it (which is not
allowed).

Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index d18328b3f93..da601dd34c0 100644
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h
@@ -3,6 +3,7 @@
 
 #include <linux/mm.h>
 #include <linux/uaccess.h>
+#include <asm/tlbflush.h>
 
 /* The usual comment is "Caches aren't brain-dead on the <architecture>".
  * Unfortunately, that doesn't apply to PA-RISC. */
@@ -112,8 +113,10 @@ void flush_dcache_page_asm(unsigned long phys_addr, unsigned long vaddr);
 static inline void
 flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
 {
-	if (PageAnon(page))
+	if (PageAnon(page)) {
+		flush_tlb_page(vma, vmaddr);
 		flush_dcache_page_asm(page_to_phys(page), vmaddr);
+	}
 }
 
 #ifdef CONFIG_DEBUG_RODATA