From 975036f6f9c8b12fbf82854ea006b4951c5be783 Mon Sep 17 00:00:00 2001 From: Eneas U de Queiroz Date: Fri, 10 Mar 2023 17:21:11 -0300 Subject: [PATCH] openssl: avoid OPENSSL_SMALL_FOOTPRINT, no-asm Building openssl with OPENSSL_SMALL_FOOTPRINT yelds only from 1% to 3% decrease in size, dropping performance from 2% to 91%, depending on the target and algorithm. For example, using AES256-GCM with 1456-bytes operations, X86_64 appears to be the least affected with 2% performance penalty and 1% reduction in size; mips drops performance by 13%, size by 3%; Arm drops 29% in performance, 2% in size. On aarch64, it slows down ghash so much that I consider it broken (-91%). SMALL_FOOTPRINT will reduce AES256-GCM performance by 88%, and size by only 1%. It makes an AES-capable CPU run AES128-GCM at 35% of the speed of Chacha20-Poly1305: Block-size=1456 bytes AES256-GCM AES128-GCM ChaCha20-Poly1305 SMALL_FOOTPRINT 62014.44 65063.23 177090.50 regular 504220.08 565630.28 182706.16 OpenSSL 1.1.1 numbers are about the same, so this should have been noticed a long time ago. This creates an option to use OPENSSL_SMALL_FOOTPRINT, but it is turned off by default unless SMALL_FLASH or LOW_MEMORY_FOOTPRINT is used. Compiling with -O3 instead of -Os, for comparison, will increase size by about 14-15%, with no measureable effect on AES256-GCM performance, and about 2% increase in Chacha20-Poly1305 performance on Aarch64. There are no Arm devices with the small flash feature, so drop the conditional default. The package is built on phase2, so even if we include an Arm device with small flash later, a no-asm library would have to be built from source anyway. Signed-off-by: Eneas U de Queiroz --- package/libs/openssl/Config.in | 18 ++++++++++++++++-- package/libs/openssl/Makefile | 7 +++++-- 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/package/libs/openssl/Config.in b/package/libs/openssl/Config.in index 6a668fe4cd..b948aab709 100644 --- a/package/libs/openssl/Config.in +++ b/package/libs/openssl/Config.in @@ -12,9 +12,23 @@ config OPENSSL_OPTIMIZE_SPEED The increase in performance and size depends on the target CPU. EC and AES seem to benefit the most. +config OPENSSL_SMALL_FOOTPRINT + bool + depends on !OPENSSL_OPTIMIZE_SPEED + default y if SMALL_FLASH || LOW_MEMORY_FOOTPRINT + prompt "Build with OPENSSL_SMALL_FOOTPRINT (read help)" + help + This turns on -DOPENSSL_SMALL_FOOTPRINT. This will save only + 1-3% of of the ipk size. The performance drop depends on + architecture and algorithm. MIPS drops 13% of performance for + a 3% decrease in ipk size. On Aarch64, for a 1% reduction in + size, ghash and GCM performance decreases 90%, while + Chacha20-Poly1305 is 15% slower. X86_64 drops 1% of its size + for 3% of performance. Other arches have not been tested. + config OPENSSL_WITH_ASM bool - default y if !SMALL_FLASH || !arm + default y prompt "Compile with optimized assembly code" depends on !arc help @@ -46,7 +60,7 @@ config OPENSSL_NO_DEPRECATED config OPENSSL_WITH_ERROR_MESSAGES bool - default y if !SMALL_FLASH && !LOW_MEMORY_FOOTPRINT + default y if !OPENSSL_SMALL_FOOTPRINT || (!SMALL_FLASH && !LOW_MEMORY_FOOTPRINT) prompt "Include error messages" help This option aids debugging, but increases package size and diff --git a/package/libs/openssl/Makefile b/package/libs/openssl/Makefile index 9fe5da9dd3..b076a9c1fa 100644 --- a/package/libs/openssl/Makefile +++ b/package/libs/openssl/Makefile @@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk PKG_NAME:=openssl PKG_VERSION:=3.0.8 -PKG_RELEASE:=4 +PKG_RELEASE:=5 PKG_BUILD_FLAGS:=no-mips16 gc-sections PKG_BUILD_PARALLEL:=1 @@ -39,6 +39,7 @@ PKG_CONFIG_DEPENDS:= \ CONFIG_OPENSSL_NO_DEPRECATED \ CONFIG_OPENSSL_OPTIMIZE_SPEED \ CONFIG_OPENSSL_PREFER_CHACHA_OVER_GCM \ + CONFIG_OPENSSL_SMALL_FOOTPRINT \ CONFIG_OPENSSL_WITH_ARIA \ CONFIG_OPENSSL_WITH_ASM \ CONFIG_OPENSSL_WITH_ASYNC \ @@ -258,7 +259,9 @@ endif ifeq ($(CONFIG_OPENSSL_OPTIMIZE_SPEED),y) TARGET_CFLAGS := $(filter-out -O%,$(TARGET_CFLAGS)) -O3 -else +endif + +ifeq ($(CONFIG_OPENSSL_SMALL_FOOTPRINT),y) OPENSSL_OPTIONS += -DOPENSSL_SMALL_FOOTPRINT endif -- 2.30.2