Add option to avoid 64-bit multiplication
Motivation is similar to NO_UDBL_DIVISION.
The alternative implementation of 64-bit mult is straightforward and aims at
obvious correctness. Also, visual examination of the generate assembly show
that it's quite efficient with clang, armcc5 and arm-clang. However current
GCC generates fairly inefficient code for it.
I tried to rework the code in order to make GCC generate more efficient code.
Unfortunately the only way to do that is to get rid of 64-bit add and handle
the carry manually, but this causes other compilers to generate less efficient
code with branches, which is not acceptable from a side-channel point of view.
So let's keep the obvious code that works for most compilers and hope future
versions of GCC learn to manage registers in a sensible way in that context.
See https://bugs.launchpad.net/gcc-arm-embedded/+bug/1775263
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index e6c7549..83011f5 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -344,6 +344,12 @@
fi
}
+# to be used instead of ! for commands run with
+# record_status or if_build_succeeded
+not() {
+ ! "$@"
+}
+
msg "info: $0 configuration"
echo "MEMORY: $MEMORY"
echo "FORCE: $FORCE"
@@ -691,6 +697,31 @@
msg "test: gcc, force 64-bit bignum limbs"
make test
+
+msg "build: MBEDTLS_NO_UDBL_DIVISION native" # ~ 10s
+cleanup
+cp "$CONFIG_H" "$CONFIG_BAK"
+scripts/config.pl full
+scripts/config.pl unset MBEDTLS_MEMORY_BACKTRACE # too slow for tests
+scripts/config.pl set MBEDTLS_NO_UDBL_DIVISION
+make CFLAGS='-Werror -O1'
+
+msg "test: MBEDTLS_NO_UDBL_DIVISION native" # ~ 10s
+make test
+
+
+msg "build: MBEDTLS_NO_64BIT_MULTIPLICATION native" # ~ 10s
+cleanup
+cp "$CONFIG_H" "$CONFIG_BAK"
+scripts/config.pl full
+scripts/config.pl unset MBEDTLS_MEMORY_BACKTRACE # too slow for tests
+scripts/config.pl set MBEDTLS_NO_64BIT_MULTIPLICATION
+make CFLAGS='-Werror -O1'
+
+msg "test: MBEDTLS_NO_64BIT_MULTIPLICATION native" # ~ 10s
+make test
+
+
msg "build: arm-none-eabi-gcc, make" # ~ 10s
cleanup
cp "$CONFIG_H" "$CONFIG_BAK"
@@ -726,7 +757,27 @@
scripts/config.pl set MBEDTLS_NO_UDBL_DIVISION
make CC=arm-none-eabi-gcc AR=arm-none-eabi-ar LD=arm-none-eabi-ld CFLAGS='-Werror -Wall -Wextra' lib
echo "Checking that software 64-bit division is not required"
-! grep __aeabi_uldiv library/*.o
+if_build_succeeded not grep __aeabi_uldiv library/*.o
+
+msg "build: arm-none-eabi-gcc MBEDTLS_NO_64BIT_MULTIPLICATION, make" # ~ 10s
+cleanup
+cp "$CONFIG_H" "$CONFIG_BAK"
+scripts/config.pl full
+scripts/config.pl unset MBEDTLS_NET_C
+scripts/config.pl unset MBEDTLS_TIMING_C
+scripts/config.pl unset MBEDTLS_FS_IO
+scripts/config.pl unset MBEDTLS_ENTROPY_NV_SEED
+scripts/config.pl set MBEDTLS_NO_PLATFORM_ENTROPY
+# following things are not in the default config
+scripts/config.pl unset MBEDTLS_HAVEGE_C # depends on timing.c
+scripts/config.pl unset MBEDTLS_THREADING_PTHREAD
+scripts/config.pl unset MBEDTLS_THREADING_C
+scripts/config.pl unset MBEDTLS_MEMORY_BACKTRACE # execinfo.h
+scripts/config.pl unset MBEDTLS_MEMORY_BUFFER_ALLOC_C # calls exit
+scripts/config.pl set MBEDTLS_NO_64BIT_MULTIPLICATION
+make CC=arm-none-eabi-gcc AR=arm-none-eabi-ar LD=arm-none-eabi-ld CFLAGS='-Werror -O1 -march=armv6-m -mthumb' lib
+echo "Checking that software 64-bit multiplication is not required"
+if_build_succeeded not grep __aeabi_lmul library/*.o
msg "build: ARM Compiler 5, make"
cleanup
