Linux/FreeBSD: Enable building without AESNI support by setting environment variable DISABLE_AESNI to 1 during build or passing NOAESNI=1 to make command

This comes following Github issue #892 and which should be solved thanks to this.

src/Crypto/cpu.c

@@ -330,7 +330,9 @@ void DetectX86Features()
 	g_hasSSE42 = g_hasSSE2 && (cpuid1[2] & (1 << 20));
 	g_hasSSE41 = g_hasSSE2 && (cpuid1[2] & (1 << 19));
 	g_hasSSSE3 = g_hasSSE2 && (cpuid1[2] & (1<<9));
+#ifndef CRYPTOPP_DISABLE_AESNI
 	g_hasAESNI = g_hasSSE2 && (cpuid1[2] & (1<<25));
+#endif
 	g_hasCLMUL = g_hasSSE2 && (cpuid1[2] & (1<<1));
 
 #if !defined (_UEFI) && ((defined(__AES__) && defined(__PCLMUL__)) || defined(__INTEL_COMPILER) || CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE)

src/Crypto/cpu.h

@@ -209,7 +209,9 @@ extern "C" {
 #endif
 
 #define CRYPTOPP_CPUID_AVAILABLE
+#ifndef CRYPTOPP_DISABLE_AESNI
 #define TC_AES_HW_CPU
+#endif
 
 // these should not be used directly
 extern volatile int g_x86DetectionDone;

src/Makefile

@@ -143,6 +143,7 @@ export PLATFORM_UNSUPPORTED := 0
 
 export CPU_ARCH ?= unknown
 export SIMD_SUPPORTED := 0
+export DISABLE_AESNI ?= 0
 
 ARCH ?= $(shell uname -m)
 
@@ -176,6 +177,9 @@ ifeq "$(origin NOSSE2)" "command line"
 	SIMD_SUPPORTED := 0
 endif
 
+ifeq "$(origin NOAESNI)" "command line"
+	DISABLE_AESNI := 1
+endif
 
 #------ Linux configuration ------
 
@@ -197,11 +201,16 @@ ifeq "$(shell uname -s)" "Linux"
 		CFLAGS += -msse2
 		CXXFLAGS += -msse2
 
-		GCC_GTEQ_440 := $(shell expr `$(CC) -dumpversion | sed -e 's/\.\([0-9][0-9]\)/\1/g' -e 's/\.\([0-9]\)/0\1/g' -e 's/^[0-9]\{3,4\}$$/&00/' -e 's/^[0-9]\{1,2\}$$/&0000/'` \>= 40400)
-		GCC_GTEQ_430 := $(shell expr `$(CC) -dumpversion | sed -e 's/\.\([0-9][0-9]\)/\1/g' -e 's/\.\([0-9]\)/0\1/g' -e 's/^[0-9]\{3,4\}$$/&00/' -e 's/^[0-9]\{1,2\}$$/&0000/'` \>= 40300)
-		ifeq "$(GCC_GTEQ_440)" "1"
-			CFLAGS += -maes
-			CXXFLAGS += -maes
+		ifeq "$(DISABLE_AESNI)" "1"
+			CFLAGS += -mno-aes -DCRYPTOPP_DISABLE_AESNI
+			CXXFLAGS += -mno-aes -DCRYPTOPP_DISABLE_AESNI
+		else
+			GCC_GTEQ_440 := $(shell expr `$(CC) -dumpversion | sed -e 's/\.\([0-9][0-9]\)/\1/g' -e 's/\.\([0-9]\)/0\1/g' -e 's/^[0-9]\{3,4\}$$/&00/' -e 's/^[0-9]\{1,2\}$$/&0000/'` \>= 40400)
+			GCC_GTEQ_430 := $(shell expr `$(CC) -dumpversion | sed -e 's/\.\([0-9][0-9]\)/\1/g' -e 's/\.\([0-9]\)/0\1/g' -e 's/^[0-9]\{3,4\}$$/&00/' -e 's/^[0-9]\{1,2\}$$/&0000/'` \>= 40300)
+			ifeq "$(GCC_GTEQ_440)" "1"
+				CFLAGS += -maes
+				CXXFLAGS += -maes
+			endif
 		endif
 
 		ifeq "$(GCC_GTEQ_430)" "1"
@@ -365,8 +374,16 @@ ifeq "$(shell uname -s)" "FreeBSD"
 	endif
 
 	ifeq "$(SIMD_SUPPORTED)" "1"
-		CFLAGS += -msse2 -maes
-		CXXFLAGS += -msse2 -maes
+		CFLAGS += -msse2
+		CXXFLAGS += -msse2
+		
+		ifeq "$(DISABLE_AESNI)" "1"
+			CFLAGS += -mno-aes -DCRYPTOPP_DISABLE_AESNI
+			CXXFLAGS += -mno-aes -DCRYPTOPP_DISABLE_AESNI
+		else
+			CFLAGS += -maes
+			CXXFLAGS += -maes
+		endif
 
 		ifeq "$(origin SSSE3)" "command line"
 			CFLAGS += -mssse3

src/Volume/Volume.make

@@ -47,12 +47,16 @@ ifeq "$(PLATFORM)" "MacOSX"
 	OBJSEX += ../Crypto/sha512_sse4.oo
 else ifeq "$(CPU_ARCH)" "x86"
 	OBJS += ../Crypto/Aes_x86.o
+ifeq "$(DISABLE_AESNI)" "0"
 	OBJS += ../Crypto/Aes_hw_cpu.o
+endif
 	OBJS += ../Crypto/sha256-x86-nayuki.o
 	OBJS += ../Crypto/sha512-x86-nayuki.o
 else ifeq "$(CPU_ARCH)" "x64"
 	OBJS += ../Crypto/Aes_x64.o
+ifeq "$(DISABLE_AESNI)" "0"
 	OBJS += ../Crypto/Aes_hw_cpu.o
+endif
 	OBJS += ../Crypto/Twofish_x64.o
 	OBJS += ../Crypto/Camellia_x64.o
 	OBJS += ../Crypto/Camellia_aesni_x64.o