[PATCH v6 6/8] crypto: caam - fix RNG buffer cache alignment

[Oleksij Rempel]

this is alternate version of linux fix:
---------------------------------------------------------------------
| commit 412c98c1bef65fe7589f1300e93735d96130307c
| Author: Steve Cornelius <steve.cornelius at freescale.com>
| Date:   Mon Jun 15 16:52:59 2015 -0700
|
| crypto: caam - fix RNG buffer cache alignment
|
| 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.
|
| Cc: stable at vger.kernel.org
| 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>
---------------------------------------------------------------------

instead we will use just dma_alloc()

Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
---
 drivers/crypto/caam/caamrng.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
index aabad0416..31a92731d 100644
--- a/drivers/crypto/caam/caamrng.c
+++ b/drivers/crypto/caam/caamrng.c
@@ -55,7 +55,7 @@
 
 /* Buffer, its dma address and lock */
 struct buf_data {
-	u8 buf[RN_BUF_SIZE];
+	u8 *buf;
 	dma_addr_t addr;
 	u32 hw_desc[DESC_JOB_O_LEN];
 #define BUF_NOT_EMPTY 0
@@ -218,6 +218,8 @@ static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
 	struct buf_data *bd = &ctx->bufs[buf_id];
 	int err;
 
+	bd->buf = dma_alloc(RN_BUF_SIZE);
+
 	err = rng_create_job_desc(ctx, buf_id);
 	if (err)
 		return err;
-- 
2.11.0