Provide amd64 specific versions of bn_mul_comba6() and bn_sqr_comba6().

These use s2n-bignum's bignum_mul_6_12_alt() and bignum_sqr_6_12_alt()
functions.

ok tb@

2 files changed, 22 insertions, 2 deletions

diff --git a/src/lib/libcrypto/bn/arch/amd64/bn_arch.c b/src/lib/libcrypto/bn/arch/amd64/bn_arch.c
index 97dc7b90c7..b8ddae6e52 100644
--- a/src/lib/libcrypto/bn/arch/amd64/bn_arch.c
+++ b/src/lib/libcrypto/bn/arch/amd64/bn_arch.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: bn_arch.c,v 1.10 2025/08/14 15:17:19 jsing Exp $ */
+/*      $OpenBSD: bn_arch.c,v 1.11 2025/08/14 15:22:54 jsing Exp $ */
 /*
  * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
  *
@@ -105,6 +105,15 @@ bn_mul_comba4(BN_ULONG *rd, const BN_ULONG *ad, const BN_ULONG *bd)
 }
 #endif
 
+#ifdef HAVE_BN_MUL_COMBA6
+void
+bn_mul_comba6(BN_ULONG *rd, const BN_ULONG *ad, const BN_ULONG *bd)
+{
+        /* XXX - consider using non-alt on CPUs that have the ADX extension. */
+        bignum_mul_6_12_alt((uint64_t *)rd, (const uint64_t *)ad, (const uint64_t *)bd);
+}
+#endif
+
 #ifdef HAVE_BN_MUL_COMBA8
 void
 bn_mul_comba8(BN_ULONG *rd, const BN_ULONG *ad, const BN_ULONG *bd)
@@ -133,6 +142,15 @@ bn_sqr_comba4(BN_ULONG *rd, const BN_ULONG *ad)
 }
 #endif
 
+#ifdef HAVE_BN_SQR_COMBA6
+void
+bn_sqr_comba6(BN_ULONG *rd, const BN_ULONG *ad)
+{
+        /* XXX - consider using non-alt on CPUs that have the ADX extension. */
+        bignum_sqr_6_12_alt((uint64_t *)rd, (const uint64_t *)ad);
+}
+#endif
+
 #ifdef HAVE_BN_SQR_COMBA8
 void
 bn_sqr_comba8(BN_ULONG *rd, const BN_ULONG *ad)
diff --git a/src/lib/libcrypto/bn/arch/amd64/bn_arch.h b/src/lib/libcrypto/bn/arch/amd64/bn_arch.h
index d07a898b80..7359f993a7 100644
--- a/src/lib/libcrypto/bn/arch/amd64/bn_arch.h
+++ b/src/lib/libcrypto/bn/arch/amd64/bn_arch.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: bn_arch.h,v 1.15 2025/08/14 15:17:19 jsing Exp $ */
+/*      $OpenBSD: bn_arch.h,v 1.16 2025/08/14 15:22:54 jsing Exp $ */
 /*
  * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
  *
@@ -32,11 +32,13 @@
 
 #define HAVE_BN_MUL_ADD_WORDS
 #define HAVE_BN_MUL_COMBA4
+#define HAVE_BN_MUL_COMBA6
 #define HAVE_BN_MUL_COMBA8
 #define HAVE_BN_MUL_WORDS
 
 #define HAVE_BN_SQR
 #define HAVE_BN_SQR_COMBA4
+#define HAVE_BN_SQR_COMBA6
 #define HAVE_BN_SQR_COMBA8
 
 #define HAVE_BN_SUB