From: Vineet Gupta <vgupta@synopsys.com>
Date: Wed, 22 May 2013 13:08:10 +0000 (+0530)
Subject: ARC: Brown paper bag bug in macro for checking cache color
X-Git-Tag: upstream/snapshot3+hdmi~5030^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3e87974dec5ec25a8a4852d9292db6be659164e6;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

ARC: Brown paper bag bug in macro for checking cache color

The VM_EXEC check in update_mmu_cache() was getting optimized away
because of a stupid error in definition of macro addr_not_cache_congruent()

The intention was to have the equivalent of following:

	if (a || (1 ? b : 0))

but we ended up with following:

	if (a || 1 ? b : 0)

And because precedence of '||' is more that that of '?', gcc was optimizing
away evaluation of <a>

Nasty Repercussions:
1. For non-aliasing configs it would mean some extraneous dcache flushes
   for non-code pages if U/K mappings were not congruent.
2. For aliasing config, some needed dcache flush for code pages might
   be missed if U/K mappings were congruent.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---

diff --git a/arch/arc/include/asm/cacheflush.h b/arch/arc/include/asm/cacheflush.h
index 9f841af..7d81974 100644
--- a/arch/arc/include/asm/cacheflush.h
+++ b/arch/arc/include/asm/cacheflush.h
@@ -99,8 +99,10 @@ static inline int cache_is_vipt_aliasing(void)
  * checks if two addresses (after page aligning) index into same cache set
  */
 #define addr_not_cache_congruent(addr1, addr2)				\
+({									\
 	cache_is_vipt_aliasing() ? 					\
-		(CACHE_COLOR(addr1) != CACHE_COLOR(addr2)) : 0		\
+		(CACHE_COLOR(addr1) != CACHE_COLOR(addr2)) : 0;		\
+})
 
 #define copy_to_user_page(vma, page, vaddr, dst, src, len)		\
 do {									\
diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index 066145b..fe1c5a0 100644
--- a/arch/arc/mm/tlb.c
+++ b/arch/arc/mm/tlb.c
@@ -444,7 +444,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr_unaligned,
 	 *	       so userspace sees the right data.
 	 *  (Avoids the flush for Non-exec + congruent mapping case)
 	 */
-	if (vma->vm_flags & VM_EXEC || addr_not_cache_congruent(paddr, vaddr)) {
+	if ((vma->vm_flags & VM_EXEC) ||
+	     addr_not_cache_congruent(paddr, vaddr)) {
 		struct page *page = pfn_to_page(pte_pfn(*ptep));
 
 		int dirty = test_and_clear_bit(PG_arch_1, &page->flags);