From: Ard Biesheuvel <ardb@kernel.org>
Date: Wed, 17 Sep 2025 21:30:18 +0000 (+0200)
Subject: crypto/arm64: sm4-ce-ccm - Avoid pointless yield of the NEON unit
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9520ef37713308e2741a5e80c4843d43bbf906eb;p=thirdparty%2Flinux.git

crypto/arm64: sm4-ce-ccm - Avoid pointless yield of the NEON unit

Kernel mode NEON sections are now preemptible on arm64, and so there is
no need to yield it when calling APIs that may sleep.

Also, move the calls to kernel_neon_end() to the same scope as
kernel_neon_begin(). This is needed for a subsequent change where a
stack buffer is allocated transparently and passed to
kernel_neon_begin().

Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---

diff --git a/arch/arm64/crypto/sm4-ce-ccm-glue.c b/arch/arm64/crypto/sm4-ce-ccm-glue.c
index e9cc1c1364ec6..e92cbdf1aaee7 100644
--- a/arch/arm64/crypto/sm4-ce-ccm-glue.c
+++ b/arch/arm64/crypto/sm4-ce-ccm-glue.c
@@ -172,35 +172,22 @@ static int ccm_crypt(struct aead_request *req, struct skcipher_walk *walk,
 	if (req->assoclen)
 		ccm_calculate_auth_mac(req, mac);
 
-	while (walk->nbytes && walk->nbytes != walk->total) {
+	while (walk->nbytes) {
 		unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE;
 
+		if (walk->nbytes == walk->total)
+			tail = 0;
+
 		sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr,
 				 walk->src.virt.addr, walk->iv,
 				 walk->nbytes - tail, mac);
 
-		kernel_neon_end();
-
 		err = skcipher_walk_done(walk, tail);
-
-		kernel_neon_begin();
 	}
 
-	if (walk->nbytes) {
-		sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr,
-				 walk->src.virt.addr, walk->iv,
-				 walk->nbytes, mac);
-
-		sm4_ce_ccm_final(rkey_enc, ctr0, mac);
+	sm4_ce_ccm_final(rkey_enc, ctr0, mac);
 
-		kernel_neon_end();
-
-		err = skcipher_walk_done(walk, 0);
-	} else {
-		sm4_ce_ccm_final(rkey_enc, ctr0, mac);
-
-		kernel_neon_end();
-	}
+	kernel_neon_end();
 
 	return err;
 }