lib/crypto: arm64/sha512: 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-512 code accordingly.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260401000548.133151-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

Author: Eric Biggers

lib/crypto/arm64/sha512-ce-core.S

@@ -93,11 +93,11 @@
 	.endm
 
 	/*
-	 * size_t __sha512_ce_transform(struct sha512_block_state *state,
-	 *				const u8 *data, size_t nblocks);
+	 * void sha512_ce_transform(struct sha512_block_state *state,
+	 *			    const u8 *data, size_t nblocks);
 	 */
 	.text
-SYM_FUNC_START(__sha512_ce_transform)
+SYM_FUNC_START(sha512_ce_transform)
 	/* load state */
 	ld1		{v8.2d-v11.2d}, [x0]
 
@@ -186,12 +186,10 @@ CPU_LE(	rev64		v19.16b, v19.16b	)
 	add		v10.2d, v10.2d, v2.2d
 	add		v11.2d, v11.2d, v3.2d
 
-	cond_yield	3f, x4, x5
 	/* handled all input blocks? */
 	cbnz		x2, 0b
 
 	/* store new state */
-3:	st1		{v8.2d-v11.2d}, [x0]
-	mov		x0, x2
+	st1		{v8.2d-v11.2d}, [x0]
 	ret
-SYM_FUNC_END(__sha512_ce_transform)
+SYM_FUNC_END(sha512_ce_transform)

lib/crypto/arm64/sha512.h

@@ -12,23 +12,16 @@ static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_sha512_insns);
 
 asmlinkage void sha512_block_data_order(struct sha512_block_state *state,
 					const u8 *data, size_t nblocks);
-asmlinkage size_t __sha512_ce_transform(struct sha512_block_state *state,
-					const u8 *data, size_t nblocks);
+asmlinkage void sha512_ce_transform(struct sha512_block_state *state,
+				    const u8 *data, size_t nblocks);
 
 static void sha512_blocks(struct sha512_block_state *state,
 			  const u8 *data, size_t nblocks)
 {
 	if (static_branch_likely(&have_sha512_insns) &&
 	    likely(may_use_simd())) {
-		do {
-			size_t rem;
-
-			scoped_ksimd()
-				rem = __sha512_ce_transform(state, data, nblocks);
-
-			data += (nblocks - rem) * SHA512_BLOCK_SIZE;
-			nblocks = rem;
-		} while (nblocks);
+		scoped_ksimd()
+			sha512_ce_transform(state, data, nblocks);
 	} else {
 		sha512_block_data_order(state, data, nblocks);
 	}