target/linux/generic/backport-5.4/080-wireguard-0052-crypto-x86-curve25519-support-assemblers-with-no-adx.patch

From 0000000000000000000000000000000000000000 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

commit 1579f1bc3b753d17a44de3457d5c6f4a5b14c752 upstream.

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>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/x86/Makefile           | 5 +++--
 arch/x86/crypto/Makefile    | 7 ++++++-
 include/crypto/curve25519.h | 6 ++++--
 3 files changed, 13 insertions(+), 5 deletions(-)

--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -198,9 +198,10 @@ avx2_instr :=$(call as-instr,vpbroadcast
 avx512_instr :=$(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)
 
--- a/arch/x86/crypto/Makefile
+++ b/arch/x86/crypto/Makefile
@@ -11,6 +11,7 @@ avx2_supported := $(call as-instr,vpgath
 avx512_supported :=$(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)
 
 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)
--- a/include/crypto/curve25519.h
+++ b/include/crypto/curve25519.h
@@ -33,7 +33,8 @@ bool __must_check curve25519(u8 mypublic
 			     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(
 				    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);