From 0299af56678278537593ed2b6af714f83031397b Mon Sep 17 00:00:00 2001
From: libo <libo@cictci.com>
Date: Mon, 2 Feb 2026 15:02:55 +0800
Subject: [PATCH] fix(sm2): fix ENABLE_SM2_NEON macro mismatch and add missing
 functions

Problems:
1. CMakeLists.txt defines -DENABLE_SM2_NEON but sm2_z256.c checks
   for ENABLE_SM2_Z256_NEON, causing NEON code path never taken
2. When NEON is enabled, sm2_z256_modp_mont_sqr, sm2_z256_modp_from_mont,
   and sm2_z256_modp_to_mont are missing due to #elif structure

Fixes:
1. Change add_definitions(-DENABLE_SM2_NEON) to
   add_definitions(-DENABLE_SM2_Z256_NEON) in CMakeLists.txt
2. Add the three missing wrapper functions in NEON code block
---
 CMakeLists.txt |  2 +-
 src/sm2_z256.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 31f9dad0..d604ff62 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -281,7 +281,7 @@ endif()
 
 if (ENABLE_SM2_NEON)
 	message(STATUS "ENABLE_SM2_NEON is ON")
-	add_definitions(-DENABLE_SM2_NEON)
+	add_definitions(-DENABLE_SM2_Z256_NEON)
 endif()
 
 if (ENABLE_SM9_ARM64)
diff --git a/src/sm2_z256.c b/src/sm2_z256.c
index e6ff43f9..8e4030a6 100644
--- a/src/sm2_z256.c
+++ b/src/sm2_z256.c
@@ -596,6 +596,28 @@ void sm2_z256_modp_mont_mul(sm2_z256_t r, const sm2_z256_t a, const sm2_z256_t b
 	}
 }
 
+void sm2_z256_modp_mont_sqr(sm2_z256_t r, const sm2_z256_t a)
+{
+	sm2_z256_modp_mont_mul(r, a, a);
+}
+
+// mont(mont(a), 1) = aR * 1 * R^-1 (mod p) = a (mod p)
+void sm2_z256_modp_from_mont(sm2_z256_t r, const sm2_z256_t a)
+{
+	sm2_z256_modp_mont_mul(r, a, SM2_Z256_ONE);
+}
+
+// 2^512 (mod p)
+static const uint64_t SM2_Z256_2e512modp_neon[4] = {
+	0x0000000200000003, 0x00000002ffffffff, 0x0000000100000001, 0x0000000400000002
+};
+
+// mont(a) = a * 2^256 (mod p) = mont_mul(a, 2^512 mod p)
+void sm2_z256_modp_to_mont(const sm2_z256_t a, uint64_t r[4])
+{
+	sm2_z256_modp_mont_mul(r, a, SM2_Z256_2e512modp_neon);
+}
+
 #else // ENABLE_SM2_Z256_NEON
 
 // z = a*b