From: Vladis Dronov <vdronov@redhat.com>
Date: Wed, 13 Apr 2022 14:16:05 +0000 (+0200)
Subject: hwrng: cn10k - Optimize cn10k_rng_read()
X-Git-Tag: v5.19-rc1~112^2~65
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=753d6770879894de10d74b437ab99ea380f1cad7;p=thirdparty%2Flinux.git

hwrng: cn10k - Optimize cn10k_rng_read()

This function assumes that sizeof(void) is 1 and arithmetic works for
void pointers. This is a GNU C extention and may not work with other
compilers. Change this by using an u8 pointer.

Also move cn10k_read_trng() out of a loop thus saving some cycles.

Fixes: 38e9791a0209 ("hwrng: cn10k - Add random number generator support")
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

diff --git a/drivers/char/hw_random/cn10k-rng.c b/drivers/char/hw_random/cn10k-rng.c
index 35001c63648bb..dd226630b67dc 100644
--- a/drivers/char/hw_random/cn10k-rng.c
+++ b/drivers/char/hw_random/cn10k-rng.c
@@ -90,6 +90,7 @@ static int cn10k_rng_read(struct hwrng *hwrng, void *data,
 {
 	struct cn10k_rng *rng = (struct cn10k_rng *)hwrng->priv;
 	unsigned int size;
+	u8 *pos = data;
 	int err = 0;
 	u64 value;
 
@@ -102,17 +103,20 @@ static int cn10k_rng_read(struct hwrng *hwrng, void *data,
 	while (size >= 8) {
 		cn10k_read_trng(rng, &value);
 
-		*((u64 *)data) = (u64)value;
+		*((u64 *)pos) = value;
 		size -= 8;
-		data += 8;
+		pos += 8;
 	}
 
-	while (size > 0) {
+	if (size > 0) {
 		cn10k_read_trng(rng, &value);
 
-		*((u8 *)data) = (u8)value;
-		size--;
-		data++;
+		while (size > 0) {
+			*pos = (u8)value;
+			value >>= 8;
+			size--;
+			pos++;
+		}
 	}
 
 	return max - size;