[PATCH v4 3/9] crypto: stm32/cryp - fix CTR counter carry

[Nicolas Toromanoff]

STM32 CRYP hardware doesn't manage CTR counter bigger than max U32, as
a workaround, at each block the current IV is saved, if the saved IV
lower u32 is 0xFFFFFFFF, the full IV is manually incremented, and set
in hardware.
Fixes: bbb2832620ac ("crypto: stm32 - Fix sparse warnings")

Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@xxxxxxxxxxx>
---
 drivers/crypto/stm32/stm32-cryp.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
index 7b55ad6d2f1a..ab4a107a0860 100644
--- a/drivers/crypto/stm32/stm32-cryp.c
+++ b/drivers/crypto/stm32/stm32-cryp.c
@@ -163,7 +163,7 @@ struct stm32_cryp {
 	struct scatter_walk     in_walk;
 	struct scatter_walk     out_walk;
 
-	u32                     last_ctr[4];
+	__be32                  last_ctr[4];
 	u32                     gcm_ctr;
 };
 
@@ -1217,27 +1217,26 @@ static void stm32_cryp_check_ctr_counter(struct stm32_cryp *cryp)
 {
 	u32 cr;
 
-	if (unlikely(cryp->last_ctr[3] == 0xFFFFFFFF)) {
-		cryp->last_ctr[3] = 0;
-		cryp->last_ctr[2]++;
-		if (!cryp->last_ctr[2]) {
-			cryp->last_ctr[1]++;
-			if (!cryp->last_ctr[1])
-				cryp->last_ctr[0]++;
-		}
+	if (unlikely(cryp->last_ctr[3] == cpu_to_be32(0xFFFFFFFF))) {
+		/*
+		 * In this case, we need to increment manually the ctr counter,
+		 * as HW doesn't handle the U32 carry.
+		 */
+		crypto_inc((u8 *)cryp->last_ctr, sizeof(cryp->last_ctr));
 
 		cr = stm32_cryp_read(cryp, CRYP_CR);
 		stm32_cryp_write(cryp, CRYP_CR, cr & ~CR_CRYPEN);
 
-		stm32_cryp_hw_write_iv(cryp, (__be32 *)cryp->last_ctr);
+		stm32_cryp_hw_write_iv(cryp, cryp->last_ctr);
 
 		stm32_cryp_write(cryp, CRYP_CR, cr);
 	}
 
-	cryp->last_ctr[0] = stm32_cryp_read(cryp, CRYP_IV0LR);
-	cryp->last_ctr[1] = stm32_cryp_read(cryp, CRYP_IV0RR);
-	cryp->last_ctr[2] = stm32_cryp_read(cryp, CRYP_IV1LR);
-	cryp->last_ctr[3] = stm32_cryp_read(cryp, CRYP_IV1RR);
+	/* The IV registers are BE  */
+	cryp->last_ctr[0] = cpu_to_be32(stm32_cryp_read(cryp, CRYP_IV0LR));
+	cryp->last_ctr[1] = cpu_to_be32(stm32_cryp_read(cryp, CRYP_IV0RR));
+	cryp->last_ctr[2] = cpu_to_be32(stm32_cryp_read(cryp, CRYP_IV1LR));
+	cryp->last_ctr[3] = cpu_to_be32(stm32_cryp_read(cryp, CRYP_IV1RR));
 }
 
 static bool stm32_cryp_irq_read_data(struct stm32_cryp *cryp)
-- 
2.17.1