netdev - [PATCH net-next] etherdevice: Optimize compare_ether_addr/ether_addr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 31 Aug 2013 01:54:16 -0700
From:	Joe Perches <joe@...ches.com>
To:	David Miller <davem@...emloft.net>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] etherdevice: Optimize
 compare_ether_addr/ether_addr_equal

When CONFIG_HAS_EFFICIENT_UNALIGNED_ACCESS is set,
optimize compare_ether_addr a little by removing an
xor and or by using a u32 and u16 comparison
instead of 3 separate u16 comparisons.

Make the ether_addr_equal_64bits code a bit simpler
by adding a test for CONFIG_64BIT and calling
ether_addr_equal otherwise.

This also slightly improves ether_addr_equal_64bits
by removing the zap_last_2bytes shifts in the !64bit
case.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 include/linux/etherdevice.h | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index c623861..2514d17 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -208,11 +208,19 @@ static inline void eth_hw_addr_random(struct net_device *dev)
  */
 static inline unsigned compare_ether_addr(const u8 *addr1, const u8 *addr2)
 {
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+	u32 fold = ((*(const u32 *)addr1) ^ (*(const u32 *)addr2));
+	fold |= ((*(const u16 *)(addr1 + 4)) ^ (*(const u16 *)(addr2 + 4)));
+
+	BUILD_BUG_ON(ETH_ALEN != 6);
+	return fold != 0;
+#else
 	const u16 *a = (const u16 *) addr1;
 	const u16 *b = (const u16 *) addr2;
 
 	BUILD_BUG_ON(ETH_ALEN != 6);
 	return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | (a[2] ^ b[2])) != 0;
+#endif
 }
 
 /**
@@ -253,16 +261,11 @@ static inline unsigned long zap_last_2bytes(unsigned long value)
 static inline bool ether_addr_equal_64bits(const u8 addr1[6+2],
 					   const u8 addr2[6+2])
 {
-#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(CONFIG_64BIT)
 	unsigned long fold = ((*(unsigned long *)addr1) ^
 			      (*(unsigned long *)addr2));
 
-	if (sizeof(fold) == 8)
-		return zap_last_2bytes(fold) == 0;
-
-	fold |= zap_last_2bytes((*(unsigned long *)(addr1 + 4)) ^
-				(*(unsigned long *)(addr2 + 4)));
-	return fold == 0;
+	return zap_last_2bytes(fold) == 0;
 #else
 	return ether_addr_equal(addr1, addr2);
 #endif


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html