lib/crypto: arm64/sha3: Remove obsolete chunking logic

Since commit aefbab8 ("arm64: fpsimd: Preserve/restore kernel mode
NEON at context switch"), kernel-mode NEON sections have been
preemptible on arm64.  And since commit 7dadeaa ("sched: Further
restrict the preemption modes"), voluntary preemption is no longer
supported on arm64 either.  Therefore, there's no longer any need to
limit the length of kernel-mode NEON sections on arm64.

Simplify the SHA-3 code accordingly.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260401000548.133151-9-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

Author: Eric Biggers

lib/crypto/arm64/sha3-ce-core.S

@@ -37,8 +37,8 @@
 	.endm
 
 	/*
-	 * size_t sha3_ce_transform(struct sha3_state *state, const u8 *data,
-	 *			    size_t nblocks, size_t block_size)
+	 * void sha3_ce_transform(struct sha3_state *state, const u8 *data,
+	 *			  size_t nblocks, size_t block_size)
 	 *
 	 * block_size is assumed to be one of 72 (SHA3-512), 104 (SHA3-384), 136
 	 * (SHA3-256 and SHAKE256), 144 (SHA3-224), or 168 (SHAKE128).
@@ -185,18 +185,16 @@ SYM_FUNC_START(sha3_ce_transform)
 	eor	 v0.16b,  v0.16b, v31.16b
 
 	cbnz	w8, 3b
-	cond_yield 4f, x8, x9
 	cbnz	x2, 0b
 
 	/* save state */
-4:	st1	{ v0.1d- v3.1d}, [x0], #32
+	st1	{ v0.1d- v3.1d}, [x0], #32
 	st1	{ v4.1d- v7.1d}, [x0], #32
 	st1	{ v8.1d-v11.1d}, [x0], #32
 	st1	{v12.1d-v15.1d}, [x0], #32
 	st1	{v16.1d-v19.1d}, [x0], #32
 	st1	{v20.1d-v23.1d}, [x0], #32
 	st1	{v24.1d}, [x0]
-	mov	x0, x2
 	ret
 SYM_FUNC_END(sha3_ce_transform)
 

lib/crypto/arm64/sha3.h

@@ -12,22 +12,15 @@
 
 static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_sha3);
 
-asmlinkage size_t sha3_ce_transform(struct sha3_state *state, const u8 *data,
-				    size_t nblocks, size_t block_size);
+asmlinkage void sha3_ce_transform(struct sha3_state *state, const u8 *data,
+				  size_t nblocks, size_t block_size);
 
 static void sha3_absorb_blocks(struct sha3_state *state, const u8 *data,
 			       size_t nblocks, size_t block_size)
 {
 	if (static_branch_likely(&have_sha3) && likely(may_use_simd())) {
-		do {
-			size_t rem;
-
-			scoped_ksimd()
-				rem = sha3_ce_transform(state, data, nblocks,
-							block_size);
-			data += (nblocks - rem) * block_size;
-			nblocks = rem;
-		} while (nblocks);
+		scoped_ksimd()
+			sha3_ce_transform(state, data, nblocks, block_size);
 	} else {
 		sha3_absorb_blocks_generic(state, data, nblocks, block_size);
 	}