Add linux runtime detection

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>

library/aesce.c

@@ -45,6 +45,26 @@
 
 #include <arm_neon.h>
 
+#if defined(__linux__)
+#include <asm/hwcap.h>
+#include <sys/auxv.h>
+#endif
+
+/*
+ * AES instruction support detection routine
+ */
+int mbedtls_aesce_has_support(void)
+{
+#if defined(__linux__)
+    unsigned long auxval = getauxval(AT_HWCAP);
+    return (auxval & (HWCAP_ASIMD | HWCAP_AES)) ==
+           (HWCAP_ASIMD | HWCAP_AES);
+#else
+    /* Suppose aes instructions are supported. */
+    return 1;
+#endif
+}
+
 #endif /* MBEDTLS_HAVE_ARM64 */
 
 #endif /* MBEDTLS_AESCE_C */

library/aesce.h

@@ -31,8 +31,8 @@
 #include "mbedtls/aes.h"
 
 
-#if !defined(MBEDTLS_HAVE_ARM64) && \
-    (defined(__aarch64__) || defined(_M_ARM64))
+#if defined(MBEDTLS_HAVE_ASM) && defined(__GNUC__) &&  \
+    defined(__aarch64__) && !defined(MBEDTLS_HAVE_ARM64)
 #define MBEDTLS_HAVE_ARM64
 #endif
 
@@ -41,6 +41,14 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
+
+/**
+ * \brief          Internal function to detect the crypto engine in CPUs.
+ *
+ * \return         1 if CPU has support for the feature, 0 otherwise
+ */
+int mbedtls_aesce_has_support(void);
+
 #ifdef __cplusplus
 }
 #endif