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From: Greg KH <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org,
	alan@lxorguk.ukuu.org.uk,
	Herbert Xu <herbert@gondor.apana.org.au>
Subject: [11/15] crypto: sha512 - Use binary and instead of modulus
Date: Thu, 16 Feb 2012 16:55:20 -0800	[thread overview]
Message-ID: <20120217005511.390624452@linuxfoundation.org> (raw)
In-Reply-To: <20120217005650.GA17119@kroah.com>

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

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

From: Herbert Xu <herbert@gondor.apana.org.au>

commit 58d7d18b5268febb8b1391c6dffc8e2aaa751fcd upstream.

The previous patch used the modulus operator over a power of 2
unnecessarily which may produce suboptimal binary code.  This
patch changes changes them to binary ands instead.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 crypto/sha512_generic.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/crypto/sha512_generic.c
+++ b/crypto/sha512_generic.c
@@ -78,7 +78,7 @@ static inline void LOAD_OP(int I, u64 *W
 
 static inline void BLEND_OP(int I, u64 *W)
 {
-	W[I % 16] += s1(W[(I-2) % 16]) + W[(I-7) % 16] + s0(W[(I-15) % 16]);
+	W[I & 15] += s1(W[(I-2) & 15]) + W[(I-7) & 15] + s0(W[(I-15) & 15]);
 }
 
 static void
@@ -105,7 +105,7 @@ sha512_transform(u64 *state, const u8 *i
 
 #define SHA512_16_79(i, a, b, c, d, e, f, g, h)			\
 	BLEND_OP(i, W);						\
-	t1 = h + e1(e) + Ch(e, f, g) + sha512_K[i] + W[(i)%16];	\
+	t1 = h + e1(e) + Ch(e, f, g) + sha512_K[i] + W[(i)&15];	\
 	t2 = e0(a) + Maj(a, b, c);				\
 	d += t1;						\
 	h = t1 + t2



  parent reply	other threads:[~2012-02-17  0:55 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-17  0:56 [00/15] 3.0.22-stable review Greg KH
2012-02-17  0:55 ` [01/15] perf evsel: Fix an issue where perf report fails to show the proper percentage Greg KH
2012-02-17  0:55 ` [02/15] perf tools: Fix perf stack to non executable on x86_64 Greg KH
2012-02-17  0:55 ` [03/15] drm/i915: no lvds quirk for AOpen MP45 Greg KH
2012-02-17  0:55 ` [04/15] hwmon: (f75375s) Fix bit shifting in f75375_write16 Greg KH
2012-02-17  0:55 ` [05/15] lib: proportion: lower PROP_MAX_SHIFT to 32 on 64-bit kernel Greg KH
2012-02-17  0:55 ` [06/15] relay: prevent integer overflow in relay_open() Greg KH
2012-02-17  0:55 ` [07/15] mac80211: timeout a single frame in the rx reorder buffer Greg KH
2012-02-17  0:55 ` [08/15] writeback: fix dereferencing NULL bdi->dev on trace_writeback_queue Greg KH
2012-02-17  0:55 ` [09/15] gpio/pca953x: Fix warning of enabled interrupts in handler Greg KH
2012-02-17  0:55 ` [10/15] hwmon: (f75375s) Fix automatic pwm mode setting for F75373 & F75375 Greg KH
2012-02-17  0:55 ` Greg KH [this message]
2012-02-17  0:55 ` [12/15] crypto: sha512 - Avoid stack bloat on i386 Greg KH
2012-02-17  0:55 ` [13/15] ALSA: intel8x0: Fix default inaudible sound on Gateway M520 Greg KH
2012-02-17  0:55 ` [14/15] xen pvhvm: do not remap pirqs onto evtchns if !xen_have_vector_callback Greg KH
2012-02-17  0:55 ` [15/15] slub: fix a possible memleak in __slab_alloc() Greg KH

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