[3.16.y-ckt stable] Patch "crypto: caam - fix RNG buffer cache alignment" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    crypto: caam - fix RNG buffer cache alignment

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt14.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 8db7421a26fc79af83b279557505a571329705d5 Mon Sep 17 00:00:00 2001
From: Steve Cornelius <steve.cornelius at freescale.com>
Date: Mon, 15 Jun 2015 16:52:59 -0700
Subject: crypto: caam - fix RNG buffer cache alignment

commit 412c98c1bef65fe7589f1300e93735d96130307c upstream.

The hwrng output buffers (2) are cast inside of a a struct (caam_rng_ctx)
allocated in one DMA-tagged region. While the kernel's heap allocator
should place the overall struct on a cacheline aligned boundary, the 2
buffers contained within may not necessarily align. Consenquently, the ends
of unaligned buffers may not fully flush, and if so, stale data will be left
behind, resulting in small repeating patterns.

This fix aligns the buffers inside the struct.

Note that not all of the data inside caam_rng_ctx necessarily needs to be
DMA-tagged, only the buffers themselves require this. However, a fix would
incur the expense of error-handling bloat in the case of allocation failure.

Signed-off-by: Steve Cornelius <steve.cornelius at freescale.com>
Signed-off-by: Victoria Milhoan <vicki.milhoan at freescale.com>
Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/crypto/caam/caamrng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
index 8c07d3153f12..18c05cae36a4 100644
--- a/drivers/crypto/caam/caamrng.c
+++ b/drivers/crypto/caam/caamrng.c
@@ -56,7 +56,7 @@

 /* Buffer, its dma address and lock */
 struct buf_data {
-	u8 buf[RN_BUF_SIZE];
+	u8 buf[RN_BUF_SIZE] ____cacheline_aligned;
 	dma_addr_t addr;
 	struct completion filled;
 	u32 hw_desc[DESC_JOB_O_LEN];