From 1579f1bc3b753d17a44de3457d5c6f4a5b14c752 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Sun, 1 Mar 2020 22:52:35 +0800
Subject: [PATCH] crypto: x86/curve25519 - support assemblers with no adx
 support

Some older version of GAS do not support the ADX instructions, similarly
to how they also don't support AVX and such. This commit adds the same
build-time detection mechanisms we use for AVX and others for ADX, and
then makes sure that the curve25519 library dispatcher calls the right
functions.

Reported-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 arch/x86/Makefile           | 5 +++--
 arch/x86/crypto/Makefile    | 7 ++++++-
 include/crypto/curve25519.h | 6 ++++--
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 94df0868804b..513a55562d75 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -194,9 +194,10 @@ avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1)
 avx512_instr :=$(call as-instr,vpmovm2b %k1$(comma)%zmm5,-DCONFIG_AS_AVX512=1)
 sha1_ni_instr :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA1_NI=1)
 sha256_ni_instr :=$(call as-instr,sha256msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA256_NI=1)
+adx_instr := $(call as-instr,adox %r10$(comma)%r10,-DCONFIG_AS_ADX=1)
 
-KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr)
-KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr)
+KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
+KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
 
 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
 
diff --git a/arch/x86/crypto/Makefile b/arch/x86/crypto/Makefile
index b69e00bf20b8..8c2e9eadee8a 100644
--- a/arch/x86/crypto/Makefile
+++ b/arch/x86/crypto/Makefile
@@ -11,6 +11,7 @@ avx2_supported := $(call as-instr,vpgatherdd %ymm0$(comma)(%eax$(comma)%ymm1\
 avx512_supported :=$(call as-instr,vpmovm2b %k1$(comma)%zmm5,yes,no)
 sha1_ni_supported :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,yes,no)
 sha256_ni_supported :=$(call as-instr,sha256msg1 %xmm0$(comma)%xmm1,yes,no)
+adx_supported := $(call as-instr,adox %r10$(comma)%r10,yes,no)
 
 obj-$(CONFIG_CRYPTO_GLUE_HELPER_X86) += glue_helper.o
 
@@ -39,7 +40,11 @@ obj-$(CONFIG_CRYPTO_AEGIS128_AESNI_SSE2) += aegis128-aesni.o
 
 obj-$(CONFIG_CRYPTO_NHPOLY1305_SSE2) += nhpoly1305-sse2.o
 obj-$(CONFIG_CRYPTO_NHPOLY1305_AVX2) += nhpoly1305-avx2.o
-obj-$(CONFIG_CRYPTO_CURVE25519_X86) += curve25519-x86_64.o
+
+# These modules require the assembler to support ADX.
+ifeq ($(adx_supported),yes)
+	obj-$(CONFIG_CRYPTO_CURVE25519_X86) += curve25519-x86_64.o
+endif
 
 # These modules require assembler to support AVX.
 ifeq ($(avx_supported),yes)
diff --git a/include/crypto/curve25519.h b/include/crypto/curve25519.h
index 4e6dc840b159..9ecb3c1f0f15 100644
--- a/include/crypto/curve25519.h
+++ b/include/crypto/curve25519.h
@@ -33,7 +33,8 @@ bool __must_check curve25519(u8 mypublic[CURVE25519_KEY_SIZE],
 			     const u8 secret[CURVE25519_KEY_SIZE],
 			     const u8 basepoint[CURVE25519_KEY_SIZE])
 {
-	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519))
+	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519) &&
+	    (!IS_ENABLED(CONFIG_CRYPTO_CURVE25519_X86) || IS_ENABLED(CONFIG_AS_ADX)))
 		curve25519_arch(mypublic, secret, basepoint);
 	else
 		curve25519_generic(mypublic, secret, basepoint);
@@ -49,7 +50,8 @@ __must_check curve25519_generate_public(u8 pub[CURVE25519_KEY_SIZE],
 				    CURVE25519_KEY_SIZE)))
 		return false;
 
-	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519))
+	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519) &&
+	    (!IS_ENABLED(CONFIG_CRYPTO_CURVE25519_X86) || IS_ENABLED(CONFIG_AS_ADX)))
 		curve25519_base_arch(pub, secret);
 	else
 		curve25519_generic(pub, secret, curve25519_base_point);