runtime/cgo: define x_cgo_inittls() for android/arm64.

On android, runtime.tls_g is a normal variable.
TLS offset is computed in x_cgo_inittls.

Change-Id: I64cfd3543040776dcdf73cad8dba54fc6aaf6f35
Reviewed-on: https://go-review.googlesource.com/17245
Reviewed-by: David Crawshaw <crawshaw@golang.org>

diff --git a/src/runtime/cgo/gcc_android_arm64.c b/src/runtime/cgo/gcc_android_arm64.c
new file mode 100644 (file)
index 0000000..5d4cefe
--- /dev/null
+++ b/src/runtime/cgo/gcc_android_arm64.c
@@ -0,0 +1,38 @@
+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include <signal.h>
+#include <stdio.h>
+#include <sys/limits.h>
+#include "libcgo.h"
+
+#define magic1 (0x23581321345589ULL)
+
+// inittls allocates a thread-local storage slot for g.
+//
+// It finds the first available slot using pthread_key_create and uses
+// it as the offset value for runtime.tlsg.
+static void
+inittls(void **tlsg, void **tlsbase)
+{
+       pthread_key_t k;
+       int i, err;
+
+       err = pthread_key_create(&k, nil);
+       if(err != 0) {
+               fatalf("pthread_key_create failed: %d", err);
+       }
+       pthread_setspecific(k, (void*)magic1);
+       for (i=0; i<PTHREAD_KEYS_MAX; i++) {
+               if (*(tlsbase+i) == (void*)magic1) {
+                       *tlsg = (void*)(i*sizeof(void *));
+                       pthread_setspecific(k, 0);
+                       return;
+               }
+       }
+       fatalf("could not find pthread key");
+}
+
+void (*x_cgo_inittls)(void **tlsg, void **tlsbase) = inittls;