linux-kernel - [PATCH v3 15/21] crypto/arm64: sha3 - Switch to 'ksimd' scoped guard API

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Message-ID: <20251008154533.3089255-38-ardb+git@google.com>
Date: Wed,  8 Oct 2025 17:45:49 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org, 
	herbert@...dor.apana.org.au, ebiggers@...nel.org, 
	Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH v3 15/21] crypto/arm64: sha3 - Switch to 'ksimd' scoped guard API

From: Ard Biesheuvel <ardb@...nel.org>

Switch to the more abstract 'scoped_ksimd()' API, which will be modified
in a future patch to transparently allocate a kernel mode FP/SIMD state
buffer on the stack, so that kernel mode FP/SIMD code remains
preemptible in principe, but without the memory overhead that adds 528
bytes to the size of struct task_struct.

Reviewed-by: Eric Biggers <ebiggers@...nel.org>
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/arm64/crypto/sha3-ce-glue.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/crypto/sha3-ce-glue.c b/arch/arm64/crypto/sha3-ce-glue.c
index b4f1001046c9..22732760edd3 100644
--- a/arch/arm64/crypto/sha3-ce-glue.c
+++ b/arch/arm64/crypto/sha3-ce-glue.c
@@ -46,9 +46,8 @@ static int sha3_update(struct shash_desc *desc, const u8 *data,
 	do {
 		int rem;
 
-		kernel_neon_begin();
-		rem = sha3_ce_transform(sctx->st, data, blocks, ds);
-		kernel_neon_end();
+		scoped_ksimd()
+			rem = sha3_ce_transform(sctx->st, data, blocks, ds);
 		data += (blocks - rem) * bs;
 		blocks = rem;
 	} while (blocks);
@@ -73,9 +72,8 @@ static int sha3_finup(struct shash_desc *desc, const u8 *src, unsigned int len,
 	memset(block + len, 0, bs - len);
 	block[bs - 1] |= 0x80;
 
-	kernel_neon_begin();
-	sha3_ce_transform(sctx->st, block, 1, ds);
-	kernel_neon_end();
+	scoped_ksimd()
+		sha3_ce_transform(sctx->st, block, 1, ds);
 	memzero_explicit(block , sizeof(block));
 
 	for (i = 0; i < ds / 8; i++)
-- 
2.51.0.710.ga91ca5db03-goog