diff mbox

[RFC,11/11] crypto: caam - fix RNG buffer cache alignment

Message ID 1434412379-11623-12-git-send-email-vicki.milhoan@freescale.com (mailing list archive)
State Accepted
Delegated to: Herbert Xu
Headers show

Commit Message

Victoria Milhoan June 15, 2015, 11:52 p.m. UTC 
From: Steve Cornelius <steve.cornelius@freescale.com>

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@freescale.com>
Signed-off-by: Victoria Milhoan <vicki.milhoan@freescale.com>
---
 drivers/crypto/caam/caamrng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Herbert Xu June 16, 2015, 6:41 a.m. UTC | #1 
On Mon, Jun 15, 2015 at 04:52:59PM -0700, Victoria Milhoan wrote:
> From: Steve Cornelius <steve.cornelius@freescale.com>
> 
> 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.

Applied to crypto with stable CC.
diff mbox

Patch

diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
index a8c4af9..dbec737 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];