ARC: Brown paper bag bug in macro for checking cache color (3e87974d) · Commits · 戴 / test

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>

arch/arc/include/asm/cacheflush.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -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 { \

arch/arc/mm/tlb.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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);

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