linux-kernel - [PATCH 3.10 128/129] arm64: Do not flush the D-cache for anonymous pages

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Date:	Mon,  6 Jan 2014 14:39:17 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Mark Brown <broonie@...nel.org>
Subject: [PATCH 3.10 128/129] arm64: Do not flush the D-cache for anonymous pages

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Catalin Marinas <catalin.marinas@....com>

commit 7249b79f6b4cc3c2aa9138dca52e535a4c789107 upstream.

The D-cache on AArch64 is VIPT non-aliasing, so there is no need to
flush it for anonymous pages.

Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Reported-by: Will Deacon <will.deacon@....com>
Acked-by: Will Deacon <will.deacon@....com>
Cc: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/mm/flush.c |    8 +++-----
 arch/arm64/mm/mmu.c   |    1 -
 2 files changed, 3 insertions(+), 6 deletions(-)

--- a/arch/arm64/mm/flush.c
+++ b/arch/arm64/mm/flush.c
@@ -77,14 +77,12 @@ void __flush_dcache_page(struct page *pa
 
 void __sync_icache_dcache(pte_t pte, unsigned long addr)
 {
-	unsigned long pfn;
-	struct page *page;
+	struct page *page = pte_page(pte);
 
-	pfn = pte_pfn(pte);
-	if (!pfn_valid(pfn))
+	/* no flushing needed for anonymous pages */
+	if (!page_mapping(page))
 		return;
 
-	page = pfn_to_page(pfn);
 	if (!test_and_set_bit(PG_dcache_clean, &page->flags)) {
 		__flush_dcache_page(page);
 		__flush_icache_all();
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -339,7 +339,6 @@ void __init paging_init(void)
 	bootmem_init();
 
 	empty_zero_page = virt_to_page(zero_page);
-	__flush_dcache_page(empty_zero_page);
 
 	/*
 	 * TTBR0 is only used for the identity mapping at this stage. Make it


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