libc: add _get_tp() private function

(cherry picked from commit 06d8a116bd6b6f70b8aedc6a6a2c4085c53f63ac)

2 files changed, 52 insertions, 0 deletions

diff --git a/lib/libc/arm/gen/Makefile.inc b/lib/libc/arm/gen/Makefile.inc
index 6cc9b69d2b0e..35aa465e4904 100644
--- a/lib/libc/arm/gen/Makefile.inc
+++ b/lib/libc/arm/gen/Makefile.inc
@@ -4,6 +4,7 @@
 SRCS+=	\
 	__aeabi_read_tp.S \
 	_ctx_start.S \
+	_get_tp.c \
 	_set_tp.c \
 	_setjmp.S \
 	alloca.S \
diff --git a/lib/libc/arm/gen/_get_tp.c b/lib/libc/arm/gen/_get_tp.c
new file mode 100644
index 000000000000..7e0285f7d6f2
--- /dev/null
+++ b/lib/libc/arm/gen/_get_tp.c
@@ -0,0 +1,51 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2021 The FreeBSD Foundation
+ *
+ * This software were developed by Konstantin Belousov
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <string.h>
+#include <stdint.h>
+#include <machine/sysarch.h>
+#include "libc_private.h"
+
+void *
+_get_tp(void)
+{
+	void *res;
+
+#ifdef ARM_TP_ADDRESS
+	res = (void *)ARM_TP_ADDRESS
+#else
+	__asm __volatile("mrc  p15, 0, %0, c13, c0, 3" : "=r" (res));
+#endif
+	return (res);
+}