crypto/armcap.c: short-circuit processor capability probe in iOS builds.

Capability probing by catching SIGILL appears to be problematic
on iOS. But since Apple universe is "monocultural", it's actually
possible to simply set pre-defined processor capability mask.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2617)

diff --git a/crypto/armcap.c b/crypto/armcap.c
index 4215766bf449fce2098b291957954b8f376875f2..29534845d1e7228ab335b2ff15cadc3f6a18220a 100644 (file)
--- a/crypto/armcap.c
+++ b/crypto/armcap.c
@@ -111,6 +111,24 @@ void OPENSSL_cpuid_setup(void)
         return;
     }
 
+# if defined(__APPLE__) && !defined(__aarch64__)
+    /*
+     * Capability probing by catching SIGILL appears to be problematic
+     * on iOS. But since Apple universe is "monocultural", it's actually
+     * possible to simply set pre-defined processor capability mask.
+     */
+    if (1) {
+        OPENSSL_armcap_P = ARMV7_NEON;
+        return;
+    }
+    /*
+     * One could do same even for __aarch64__ iOS builds. It's not done
+     * exclusively for reasons of keeping code unified across platforms.
+     * Unified code works because it never triggers SIGILL on Apple
+     * devices...
+     */
+# endif
+
     sigfillset(&all_masked);
     sigdelset(&all_masked, SIGILL);
     sigdelset(&all_masked, SIGTRAP);