From d34b0072a28682386c60b3ced265cdb4061330a5 Mon Sep 17 00:00:00 2001
From: Sean Parkinson <sean@wolfssl.com>
Date: Mon, 7 Dec 2020 11:02:15 +1000
Subject: [PATCH] ARM: identify ARM CPU for Thumb and Cortex

Better detailed check of CPU architecture for 32-bit byte reversal asm
---
 configure.ac         | 19 +++++++++++++++----
 wolfcrypt/src/misc.c | 10 ++++++----
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/configure.ac b/configure.ac
index 5144db7fc..0f52e826f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4897,12 +4897,12 @@ if test "$ENABLED_SP_ASM" = "yes"; then
     ;;
   *arm*)
     if test $host_alias = "thumb"; then
-      AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_THUMB_ASM -mthumb -march=armv6"
+      AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_THUMB_ASM"
       AM_CCASFLAGS="$AM_CCASFLAGS -DWOLFSSL_SP_ARM_THUMB_ASM"
       ENABLED_SP_ARM_THUMB_ASM=yes
     else
       if test $host_alias = "cortex"; then
-        AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_CORTEX_M_ASM -mcpu=cortex-r5"
+        AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_CORTEX_M_ASM"
         AM_CCASFLAGS="$AM_CCASFLAGS -DWOLFSSL_SP_ARM_CORTEX_M_ASM"
         ENABLED_SP_ARM_CORTEX_ASM=yes
       else
@@ -5008,10 +5008,10 @@ if test "$ENABLED_SP_MATH_ALL" = "yes"; then
     ;;
   *arm*)
     if test $host_alias = "thumb"; then
-      AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_THUMB -mthumb -march=armv6"
+      AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_THUMB"
     else
       if test $host_alias = "cortex"; then
-        AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_CORTEX_M -mcpu=cortex-m4"
+        AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM_CORTEX_M"
       else
         AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_SP_ARM32"
       fi
@@ -5474,6 +5474,17 @@ do
 done
 AM_CFLAGS=$NEW_AM_CFLAGS])
 
+case $host_cpu in
+  *arm*)
+    if test $host_alias = "thumb"; then
+      AM_CFLAGS="$AM_CFLAGS -mthumb -march=armv6"
+    else
+      if test $host_alias = "cortex"; then
+        AM_CFLAGS="$AM_CFLAGS -mcpu=cortex-r5"
+      fi
+    fi
+    ;;
+esac
 
 ################################################################################
 # Check for build-type conflicts                                               #
diff --git a/wolfcrypt/src/misc.c b/wolfcrypt/src/misc.c
index be8750b9c..99119dc93 100644
--- a/wolfcrypt/src/misc.c
+++ b/wolfcrypt/src/misc.c
@@ -127,16 +127,18 @@ WC_STATIC WC_INLINE word32 ByteReverseWord32(word32 value)
 #elif defined(WOLF_ALLOW_BUILTIN) && \
         defined(__GNUC_PREREQ) && __GNUC_PREREQ(4, 3)
     return (word32)__builtin_bswap32(value);
-#elif defined(__arm__) && defined(__GNUC__)
+#elif defined(WOLFSSL_BYTESWAP32_ASM) && defined(__GNUC__) && \
+      defined(__aarch64__)
     __asm__ volatile (
-        "REV %0, %0  \n"
+        "REV32 %0, %0  \n"
         : "+r" (value)
         :
     );
     return value;
-#elif defined(__aarch64__) && defined(__GNUC__)
+#elif defined(WOLFSSL_BYTESWAP32_ASM) && defined(__GNUC__) && \
+      (defined(__thumb__) || defined(__arm__))
     __asm__ volatile (
-        "REV32 %0, %0  \n"
+        "REV %0, %0  \n"
         : "+r" (value)
         :
     );