linux-kernel - [PATCH 2/4] x86: Use clflushopt in clflush_cache

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Date:	Wed, 26 Feb 2014 12:06:50 -0700
From:	Ross Zwisler <ross.zwisler@...ux.intel.com>
To:	linux-kernel@...r.kernel.org
Cc:	Ross Zwisler <ross.zwisler@...ux.intel.com>,
	H Peter Anvin <h.peter.anvin@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 2/4] x86: Use clflushopt in clflush_cache_range

If clflushopt is available on the system, use it instead of clflush in
clflush_cache_range.

Signed-off-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc: H Peter Anvin <h.peter.anvin@...el.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/mm/pageattr.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index bb32480..11d500a 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -125,8 +125,8 @@ within(unsigned long addr, unsigned long start, unsigned long end)
  * @vaddr:	virtual start address
  * @size:	number of bytes to flush
  *
- * clflush is an unordered instruction which needs fencing with mfence
- * to avoid ordering issues.
+ * clflushopt is an unordered instruction which needs fencing with mfence or
+ * sfence to avoid ordering issues.
  */
 void clflush_cache_range(void *vaddr, unsigned int size)
 {
@@ -135,11 +135,11 @@ void clflush_cache_range(void *vaddr, unsigned int size)
 	mb();
 
 	for (; vaddr < vend; vaddr += boot_cpu_data.x86_clflush_size)
-		clflush(vaddr);
+		clflushopt(vaddr);
 	/*
 	 * Flush any possible final partial cacheline:
 	 */
-	clflush(vend);
+	clflushopt(vend);
 
 	mb();
 }
-- 
1.7.10.4

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