[PATCH v2 2/9] crypto: arm64/sha1-ce - simplify NEON yield

[Ard Biesheuvel <ardb@kernel.org>]

Instead of calling into kernel_neon_end() and kernel_neon_begin() (and
potentially into schedule()) from the assembler code when running in
task mode and a reschedule is pending, perform only the preempt count
check in assembler, but simply return early in this case, and let the C
code deal with the consequences.

This reverts commit 7df8d164753e6e6f229b72767595072bc6a71f48.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/crypto/sha1-ce-core.S | 47 +++++++-------------
 arch/arm64/crypto/sha1-ce-glue.c | 22 ++++-----
 2 files changed, 29 insertions(+), 40 deletions(-)

diff --git a/arch/arm64/crypto/sha1-ce-core.S b/arch/arm64/crypto/sha1-ce-core.S
index 92d0d2753e81..8c02bbc2684e 100644
--- a/arch/arm64/crypto/sha1-ce-core.S
+++ b/arch/arm64/crypto/sha1-ce-core.S
@@ -62,40 +62,34 @@
 	.endm
 
 	/*
-	 * void sha1_ce_transform(struct sha1_ce_state *sst, u8 const *src,
-	 *			  int blocks)
+	 * int sha1_ce_transform(struct sha1_ce_state *sst, u8 const *src,
+	 *			 int blocks)
 	 */
 SYM_FUNC_START(sha1_ce_transform)
-	frame_push	3
-
-	mov		x19, x0
-	mov		x20, x1
-	mov		x21, x2
-
 	/* load round constants */
-0:	loadrc		k0.4s, 0x5a827999, w6
+	loadrc		k0.4s, 0x5a827999, w6
 	loadrc		k1.4s, 0x6ed9eba1, w6
 	loadrc		k2.4s, 0x8f1bbcdc, w6
 	loadrc		k3.4s, 0xca62c1d6, w6
 
 	/* load state */
-	ld1		{dgav.4s}, [x19]
-	ldr		dgb, [x19, #16]
+	ld1		{dgav.4s}, [x0]
+	ldr		dgb, [x0, #16]
 
 	/* load sha1_ce_state::finalize */
 	ldr_l		w4, sha1_ce_offsetof_finalize, x4
-	ldr		w4, [x19, x4]
+	ldr		w4, [x0, x4]
 
 	/* load input */
-1:	ld1		{v8.4s-v11.4s}, [x20], #64
-	sub		w21, w21, #1
+0:	ld1		{v8.4s-v11.4s}, [x1], #64
+	sub		w2, w2, #1
 
 CPU_LE(	rev32		v8.16b, v8.16b		)
 CPU_LE(	rev32		v9.16b, v9.16b		)
 CPU_LE(	rev32		v10.16b, v10.16b	)
 CPU_LE(	rev32		v11.16b, v11.16b	)
 
-2:	add		t0.4s, v8.4s, k0.4s
+1:	add		t0.4s, v8.4s, k0.4s
 	mov		dg0v.16b, dgav.16b
 
 	add_update	c, ev, k0,  8,  9, 10, 11, dgb
@@ -126,25 +120,18 @@ CPU_LE(	rev32		v11.16b, v11.16b	)
 	add		dgbv.2s, dgbv.2s, dg1v.2s
 	add		dgav.4s, dgav.4s, dg0v.4s
 
-	cbz		w21, 3f
-
-	if_will_cond_yield_neon
-	st1		{dgav.4s}, [x19]
-	str		dgb, [x19, #16]
-	do_cond_yield_neon
+	cbz		w2, 2f
+	cond_yield	3f, x5
 	b		0b
-	endif_yield_neon
-
-	b		1b
 
 	/*
 	 * Final block: add padding and total bit count.
 	 * Skip if the input size was not a round multiple of the block size,
 	 * the padding is handled by the C code in that case.
 	 */
-3:	cbz		x4, 4f
+2:	cbz		x4, 3f
 	ldr_l		w4, sha1_ce_offsetof_count, x4
-	ldr		x4, [x19, x4]
+	ldr		x4, [x0, x4]
 	movi		v9.2d, #0
 	mov		x8, #0x80000000
 	movi		v10.2d, #0
@@ -153,11 +140,11 @@ CPU_LE(	rev32		v11.16b, v11.16b	)
 	mov		x4, #0
 	mov		v11.d[0], xzr
 	mov		v11.d[1], x7
-	b		2b
+	b		1b
 
 	/* store new state */
-4:	st1		{dgav.4s}, [x19]
-	str		dgb, [x19, #16]
-	frame_pop
+3:	st1		{dgav.4s}, [x0]
+	str		dgb, [x0, #16]
+	mov		w0, w2
 	ret
 SYM_FUNC_END(sha1_ce_transform)
diff --git a/arch/arm64/crypto/sha1-ce-glue.c b/arch/arm64/crypto/sha1-ce-glue.c
index c1362861765f..71fa4f1122d7 100644
--- a/arch/arm64/crypto/sha1-ce-glue.c
+++ b/arch/arm64/crypto/sha1-ce-glue.c
@@ -29,14 +29,22 @@ struct sha1_ce_state {
 extern const u32 sha1_ce_offsetof_count;
 extern const u32 sha1_ce_offsetof_finalize;
 
-asmlinkage void sha1_ce_transform(struct sha1_ce_state *sst, u8 const *src,
-				  int blocks);
+asmlinkage int sha1_ce_transform(struct sha1_ce_state *sst, u8 const *src,
+				 int blocks);
 
 static void __sha1_ce_transform(struct sha1_state *sst, u8 const *src,
 				int blocks)
 {
-	sha1_ce_transform(container_of(sst, struct sha1_ce_state, sst), src,
-			  blocks);
+	while (blocks) {
+		int rem;
+
+		kernel_neon_begin();
+		rem = sha1_ce_transform(container_of(sst, struct sha1_ce_state,
+						     sst), src, blocks);
+		kernel_neon_end();
+		src += (blocks - rem) * SHA1_BLOCK_SIZE;
+		blocks = rem;
+	}
 }
 
 const u32 sha1_ce_offsetof_count = offsetof(struct sha1_ce_state, sst.count);
@@ -51,9 +59,7 @@ static int sha1_ce_update(struct shash_desc *desc, const u8 *data,
 		return crypto_sha1_update(desc, data, len);
 
 	sctx->finalize = 0;
-	kernel_neon_begin();
 	sha1_base_do_update(desc, data, len, __sha1_ce_transform);
-	kernel_neon_end();
 
 	return 0;
 }
@@ -73,11 +79,9 @@ static int sha1_ce_finup(struct shash_desc *desc, const u8 *data,
 	 */
 	sctx->finalize = finalize;
 
-	kernel_neon_begin();
 	sha1_base_do_update(desc, data, len, __sha1_ce_transform);
 	if (!finalize)
 		sha1_base_do_finalize(desc, __sha1_ce_transform);
-	kernel_neon_end();
 	return sha1_base_finish(desc, out);
 }
 
@@ -89,9 +93,7 @@ static int sha1_ce_final(struct shash_desc *desc, u8 *out)
 		return crypto_sha1_finup(desc, NULL, 0, out);
 
 	sctx->finalize = 0;
-	kernel_neon_begin();
 	sha1_base_do_finalize(desc, __sha1_ce_transform);
-	kernel_neon_end();
 	return sha1_base_finish(desc, out);
 }
 
-- 
2.30.0