[3/4] crypto/arm64: sha1 - reduce performance impact of NEON yield checks

Message ID 20180724171224.17363-4-ard.biesheuvel@linaro.org
State New
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Series
  • crypto/arm64: reduce impact of NEON yield checks
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Commit Message

Ard Biesheuvel July 24, 2018, 5:12 p.m.
Only perform the NEON yield check for every 4 blocks of input, to
prevent taking a considerable performance hit on cores with very
fast crypto instructions and comparatively slow memory accesses,
such as the Cortex-A53.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 arch/arm64/crypto/sha1-ce-core.S | 3 +++
 1 file changed, 3 insertions(+)

-- 
2.11.0

Patch

diff --git a/arch/arm64/crypto/sha1-ce-core.S b/arch/arm64/crypto/sha1-ce-core.S
index 78eb35fb5056..f592c55218d0 100644
--- a/arch/arm64/crypto/sha1-ce-core.S
+++ b/arch/arm64/crypto/sha1-ce-core.S
@@ -129,6 +129,9 @@  CPU_LE(	rev32		v11.16b, v11.16b	)
 	add		dgbv.2s, dgbv.2s, dg1v.2s
 	add		dgav.4s, dgav.4s, dg0v.4s
 
+	tst		w21, #0x3		// yield only every 4 blocks
+	b.ne		1b
+
 	cbz		w21, 3f
 
 	if_will_cond_yield_neon