lib/crypto: arm64/sha1: 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-1 code accordingly.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260401000548.133151-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

Author: Eric Biggers

lib/crypto/arm64/sha1-ce-core.S

@@ -62,10 +62,10 @@
 	.endm
 
 	/*
-	 * size_t __sha1_ce_transform(struct sha1_block_state *state,
-	 *			      const u8 *data, size_t nblocks);
+	 * void sha1_ce_transform(struct sha1_block_state *state,
+	 *			  const u8 *data, size_t nblocks);
 	 */
-SYM_FUNC_START(__sha1_ce_transform)
+SYM_FUNC_START(sha1_ce_transform)
 	/* load round constants */
 	loadrc		k0.4s, 0x5a827999, w6
 	loadrc		k1.4s, 0x6ed9eba1, w6
@@ -116,15 +116,11 @@ CPU_LE(	rev32		v11.16b, v11.16b	)
 	add		dgbv.2s, dgbv.2s, dg1v.2s
 	add		dgav.4s, dgav.4s, dg0v.4s
 
-	/* return early if voluntary preemption is needed */
-	cond_yield	1f, x5, x6
-
 	/* handled all input blocks? */
 	cbnz		x2, 0b
 
 	/* store new state */
-1:	st1		{dgav.4s}, [x0]
+	st1		{dgav.4s}, [x0]
 	str		dgb, [x0, #16]
-	mov		x0, x2
 	ret
-SYM_FUNC_END(__sha1_ce_transform)
+SYM_FUNC_END(sha1_ce_transform)

lib/crypto/arm64/sha1.h

@@ -9,22 +9,15 @@
 
 static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_ce);
 
-asmlinkage size_t __sha1_ce_transform(struct sha1_block_state *state,
-				      const u8 *data, size_t nblocks);
+asmlinkage void sha1_ce_transform(struct sha1_block_state *state,
+				  const u8 *data, size_t nblocks);
 
 static void sha1_blocks(struct sha1_block_state *state,
 			const u8 *data, size_t nblocks)
 {
 	if (static_branch_likely(&have_ce) && likely(may_use_simd())) {
-		do {
-			size_t rem;
-
-			scoped_ksimd()
-				rem = __sha1_ce_transform(state, data, nblocks);
-
-			data += (nblocks - rem) * SHA1_BLOCK_SIZE;
-			nblocks = rem;
-		} while (nblocks);
+		scoped_ksimd()
+			sha1_ce_transform(state, data, nblocks);
 	} else {
 		sha1_blocks_generic(state, data, nblocks);
 	}