[PATCH v2 4/4] arm64: accelerate crc32_be

[Kevin Bracey]

It makes no sense to leave crc32_be using the generic code while we
only accelerate the little-endian ops.

Even though the big-endian form doesn't fit as smoothly into the arm64,
we can speed it up and avoid hitting the D cache.

Tested on Cortex-A53. Without acceleration:

    crc32: CRC_LE_BITS = 64, CRC_BE BITS = 64
    crc32: self tests passed, processed 225944 bytes in 192240 nsec
    crc32c: CRC_LE_BITS = 64
    crc32c: self tests passed, processed 112972 bytes in 21360 nsec

With acceleration:

    crc32: CRC_LE_BITS = 64, CRC_BE BITS = 64
    crc32: self tests passed, processed 225944 bytes in 53480 nsec
    crc32c: CRC_LE_BITS = 64
    crc32c: self tests passed, processed 112972 bytes in 21480 nsec

Signed-off-by: Kevin Bracey <kevin at bracey.fi>
Tested-by: Ard Biesheuvel <ardb at kernel.org>
Reviewed-by: Ard Biesheuvel <ardb at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
---
 arch/arm64/lib/crc32.S | 87 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 73 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/lib/crc32.S b/arch/arm64/lib/crc32.S
index 0f9e10ecda23..8340dccff46f 100644
--- a/arch/arm64/lib/crc32.S
+++ b/arch/arm64/lib/crc32.S
@@ -11,7 +11,44 @@
 
 	.arch		armv8-a+crc
 
-	.macro		__crc32, c
+	.macro		byteorder, reg, be
+	.if		\be
+CPU_LE( rev		\reg, \reg	)
+	.else
+CPU_BE( rev		\reg, \reg	)
+	.endif
+	.endm
+
+	.macro		byteorder16, reg, be
+	.if		\be
+CPU_LE( rev16		\reg, \reg	)
+	.else
+CPU_BE( rev16		\reg, \reg	)
+	.endif
+	.endm
+
+	.macro		bitorder, reg, be
+	.if		\be
+	rbit		\reg, \reg
+	.endif
+	.endm
+
+	.macro		bitorder16, reg, be
+	.if		\be
+	rbit		\reg, \reg
+	lsr		\reg, \reg, #16
+	.endif
+	.endm
+
+	.macro		bitorder8, reg, be
+	.if		\be
+	rbit		\reg, \reg
+	lsr		\reg, \reg, #24
+	.endif
+	.endm
+
+	.macro		__crc32, c, be=0
+	bitorder	w0, \be
 	cmp		x2, #16
 	b.lt		8f			// less than 16 bytes
 
@@ -24,10 +61,14 @@
 	add		x8, x8, x1
 	add		x1, x1, x7
 	ldp		x5, x6, [x8]
-CPU_BE(	rev		x3, x3		)
-CPU_BE(	rev		x4, x4		)
-CPU_BE(	rev		x5, x5		)
-CPU_BE(	rev		x6, x6		)
+	byteorder	x3, \be
+	byteorder	x4, \be
+	byteorder	x5, \be
+	byteorder	x6, \be
+	bitorder	x3, \be
+	bitorder	x4, \be
+	bitorder	x5, \be
+	bitorder	x6, \be
 
 	tst		x7, #8
 	crc32\c\()x	w8, w0, x3
@@ -55,33 +96,43 @@ CPU_BE(	rev		x6, x6		)
 32:	ldp		x3, x4, [x1], #32
 	sub		x2, x2, #32
 	ldp		x5, x6, [x1, #-16]
-CPU_BE(	rev		x3, x3		)
-CPU_BE(	rev		x4, x4		)
-CPU_BE(	rev		x5, x5		)
-CPU_BE(	rev		x6, x6		)
+	byteorder	x3, \be
+	byteorder	x4, \be
+	byteorder	x5, \be
+	byteorder	x6, \be
+	bitorder	x3, \be
+	bitorder	x4, \be
+	bitorder	x5, \be
+	bitorder	x6, \be
 	crc32\c\()x	w0, w0, x3
 	crc32\c\()x	w0, w0, x4
 	crc32\c\()x	w0, w0, x5
 	crc32\c\()x	w0, w0, x6
 	cbnz		x2, 32b
-0:	ret
+0:	bitorder	w0, \be
+	ret
 
 8:	tbz		x2, #3, 4f
 	ldr		x3, [x1], #8
-CPU_BE(	rev		x3, x3		)
+	byteorder	x3, \be
+	bitorder	x3, \be
 	crc32\c\()x	w0, w0, x3
 4:	tbz		x2, #2, 2f
 	ldr		w3, [x1], #4
-CPU_BE(	rev		w3, w3		)
+	byteorder	w3, \be
+	bitorder	w3, \be
 	crc32\c\()w	w0, w0, w3
 2:	tbz		x2, #1, 1f
 	ldrh		w3, [x1], #2
-CPU_BE(	rev16		w3, w3		)
+	byteorder16	w3, \be
+	bitorder16	w3, \be
 	crc32\c\()h	w0, w0, w3
 1:	tbz		x2, #0, 0f
 	ldrb		w3, [x1]
+	bitorder8	w3, \be
 	crc32\c\()b	w0, w0, w3
-0:	ret
+0:	bitorder	w0, \be
+	ret
 	.endm
 
 	.align		5
@@ -99,3 +150,11 @@ alternative_if_not ARM64_HAS_CRC32
 alternative_else_nop_endif
 	__crc32		c
 SYM_FUNC_END(__crc32c_le)
+
+	.align		5
+SYM_FUNC_START(crc32_be)
+alternative_if_not ARM64_HAS_CRC32
+	b		crc32_be_base
+alternative_else_nop_endif
+	__crc32		be=1
+SYM_FUNC_END(crc32_be)
-- 
2.25.1