[PATCH v2 5/7] crypto: stm32 - check request size and scatterlist size when using DMA.

[Thomas BOURGOIN]

From: Thomas Bourgoin <thomas.bourgoin at foss.st.com>

When we are sending the data to HASH with the DMA, we send all the data
provided in the scatterlists of the request.
But in some cases (ex : tcrypt performances tests), we should only send
req->nbytes
When iterating through the scatterlist we verify if it is the last
scatterlist or if the number of bytes sent plus the data of the current
scatterlist is superior of the total number of bytes to hash.

Signed-off-by: Thomas Bourgoin <thomas.bourgoin at foss.st.com>
---
 drivers/crypto/stm32/stm32-hash.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/crypto/stm32/stm32-hash.c b/drivers/crypto/stm32/stm32-hash.c
index 519fb716acee..701995a72e57 100644
--- a/drivers/crypto/stm32/stm32-hash.c
+++ b/drivers/crypto/stm32/stm32-hash.c
@@ -659,8 +659,9 @@ static int stm32_hash_dma_send(struct stm32_hash_dev *hdev)
 	struct stm32_hash_request_ctx *rctx = ahash_request_ctx(hdev->req);
 	u32 *buffer = (void *)rctx->state.buffer;
 	struct scatterlist sg[1], *tsg;
-	int err = 0, len = 0, reg, ncp = 0;
-	unsigned int i;
+	int err = 0, reg, ncp = 0;
+	unsigned int i, len = 0, bufcnt = 0;
+	bool is_last = false;
 
 	rctx->sg = hdev->req->src;
 	rctx->total = hdev->req->nbytes;
@@ -681,7 +682,9 @@ static int stm32_hash_dma_send(struct stm32_hash_dev *hdev)
 		sg[0] = *tsg;
 		len = sg->length;
 
-		if (sg_is_last(sg)) {
+		if (sg_is_last(sg) || (bufcnt + sg[0].length) >= rctx->total) {
+			sg->length = rctx->total - bufcnt;
+			is_last = true;
 			if (hdev->dma_mode == 1) {
 				len = (ALIGN(sg->length, 16) - 16);
 
@@ -707,13 +710,15 @@ static int stm32_hash_dma_send(struct stm32_hash_dev *hdev)
 			return -ENOMEM;
 		}
 
-		err = stm32_hash_xmit_dma(hdev, sg, len,
-					  !sg_is_last(sg));
+		err = stm32_hash_xmit_dma(hdev, sg, len, !is_last);
 
+		bufcnt += sg[0].length;
 		dma_unmap_sg(hdev->dev, sg, 1, DMA_TO_DEVICE);
 
 		if (err == -ENOMEM)
 			return err;
+		if (is_last)
+			break;
 	}
 
 	if (hdev->dma_mode == 1) {
-- 
2.25.1