commit aa9493a4111e88ec1918dca5b1abb281faa405b6
author Gilles Peskine <Gilles.Peskine@arm.com> Wed Sep 12 14:44:03 2018 +0200
committer Gilles Peskine <Gilles.Peskine@arm.com> Wed Jul 22 03:17:23 2020 +0200
tree a6aeac0b57985f4ea2b9981ada30e682b25ed0e1
parent e8c04fed5129a2fdf89d0aad8746420b5bceb634

Add guards around code that is specific to dynamically-loaded groups

For some curves (semi-coincidentally, short Weierstrass curves), the
ECP module calculates some group parameters dynamically. Build the
code to calculate the parameters only if a relevant curve is enabled.
This fixes an unused function warning when building with only
Montgomery curves.

Signed-off-by: Gilles Peskine <gilles.peskine@arm.com>

library/ecp_curves.c

diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 92bbb89..137ef1e 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -553,6 +553,22 @@
 };
 #endif /* MBEDTLS_ECP_DP_BP512R1_ENABLED */
 
+#if defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_BP256R1_ENABLED)   ||   \
+    defined(MBEDTLS_ECP_DP_BP384R1_ENABLED)   ||   \
+    defined(MBEDTLS_ECP_DP_BP512R1_ENABLED)   ||   \
+    defined(MBEDTLS_ECP_DP_SECP192K1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP224K1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP256K1_ENABLED)
+/* For these curves, we build the group parameters dynamically. */
+#define ECP_LOAD_GROUP
+#endif
+
+#if defined(ECP_LOAD_GROUP)
 /*
  * Create an MPI from embedded constants
  * (assumes len is an exact multiple of sizeof mbedtls_mpi_uint)
@@ -603,6 +619,7 @@
 
     return( 0 );
 }
+#endif /* ECP_LOAD_GROUP */
 
 #if defined(MBEDTLS_ECP_NIST_OPTIM)
 /* Forward declarations */
@@ -644,6 +661,7 @@
 static int ecp_mod_p256k1( mbedtls_mpi * );
 #endif
 
+#if defined(ECP_LOAD_GROUP)
 #define LOAD_GROUP_A( G )   ecp_group_load( grp,            \
                             G ## _p,  sizeof( G ## _p  ),   \
                             G ## _a,  sizeof( G ## _a  ),   \
@@ -659,6 +677,7 @@
                             G ## _gx, sizeof( G ## _gx ),   \
                             G ## _gy, sizeof( G ## _gy ),   \
                             G ## _n,  sizeof( G ## _n  ) )
+#endif /* ECP_LOAD_GROUP */
 
 #if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
 /*