Support SHA-512 hwcap detection on old libc
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/sha512.c b/library/sha512.c
index 6011254..6dcea8d 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -102,6 +102,14 @@
# if defined(__linux__)
/* Our preferred method of detection is getauxval() */
# include <sys/auxv.h>
+# if !defined(HWCAP_SHA512)
+/* The same header that declares getauxval() should provide the HWCAP_xxx
+ * constants to analyze its return value. However, the libc may be too
+ * old to have the constant that we need. So if it's missing, assume that
+ * the value is the same one used by the Linux kernel ABI.
+ */
+# define HWCAP_SHA512 (1 << 21)
+# endif
# endif
/* Use SIGILL on Unix, and fall back to it on Linux */
# include <signal.h>