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)

1 files changed, 18 insertions, 0 deletions

diff --git a/crypto/armcap.c b/crypto/armcap.c
index 4215766bf4..29534845d1 100644
--- 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);