[PATCH v2 3/3] libgcc: Add basic support for aarch64-gnu (GNU/Hurd on AArch64)

[Sergey Bugaev <bugaevc@gmail.com>]

There is currently no unwinding implementation.

libgcc/ChangeLog:

	* config.host: Recognize aarch64*-*-gnu* hosts.
	* config/aarch64/gnu-unwind.h: New file.
	* config/aarch64/heap-trampoline.c
	(allocate_trampoline_page): Support GNU/Hurd.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
 libgcc/config.host                      |  9 +++++++
 libgcc/config/aarch64/gnu-unwind.h      | 36 +++++++++++++++++++++++++
 libgcc/config/aarch64/heap-trampoline.c |  4 +--
 3 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 libgcc/config/aarch64/gnu-unwind.h

diff --git a/libgcc/config.host b/libgcc/config.host
index 59a42d3a0..e75a7af64 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -448,6 +448,15 @@ aarch64*-*-linux*)
 	tmake_file="${tmake_file} t-dfprules"
 	tmake_file="${tmake_file} ${cpu_type}/t-heap-trampoline"
 	;;
+aarch64*-*-gnu*)
+	extra_parts="$extra_parts crtfastmath.o"
+	md_unwind_header=aarch64/gnu-unwind.h
+	tmake_file="${tmake_file} ${cpu_type}/t-aarch64"
+	tmake_file="${tmake_file} ${cpu_type}/t-lse t-slibgcc-libgcc"
+	tmake_file="${tmake_file} ${cpu_type}/t-softfp t-softfp t-crtfm"
+	tmake_file="${tmake_file} t-dfprules"
+	tmake_file="${tmake_file} ${cpu_type}/t-heap-trampoline"
+	;;
 aarch64*-*-vxworks7*)
 	extra_parts="$extra_parts crtfastmath.o"
 	md_unwind_header=aarch64/aarch64-unwind.h
diff --git a/libgcc/config/aarch64/gnu-unwind.h b/libgcc/config/aarch64/gnu-unwind.h
new file mode 100644
index 000000000..d9e485a18
--- /dev/null
+++ b/libgcc/config/aarch64/gnu-unwind.h
@@ -0,0 +1,36 @@
+/* DWARF2 EH unwinding support for GNU Hurd: aarch64.
+   Copyright (C) 2020-2024 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+/* Always include AArch64 unwinder header file.  */
+#include "config/aarch64/aarch64-unwind.h"
+
+#ifndef inhibit_libc
+
+#include <signal.h>
+
+/*
+ * TODO: support for aarch64 needs to be implemented.
+ */
+
+#endif /* ifndef inhibit_libc */
diff --git a/libgcc/config/aarch64/heap-trampoline.c b/libgcc/config/aarch64/heap-trampoline.c
index 885df629d..26957a3ee 100644
--- a/libgcc/config/aarch64/heap-trampoline.c
+++ b/libgcc/config/aarch64/heap-trampoline.c
@@ -29,7 +29,7 @@ void *allocate_trampoline_page (void);
 void __gcc_nested_func_ptr_created (void *chain, void *func, void *dst);
 void __gcc_nested_func_ptr_deleted (void);
 
-#if defined(__linux__)
+#if defined(__linux__) || defined(__gnu_hurd__)
 static const unsigned char aarch64_trampoline_insns[6][4] = {
   {0x5f, 0x24, 0x03, 0xd5}, /* hint    34 */
   {0xb1, 0x00, 0x00, 0x58}, /* ldr     x17, .+20 */
@@ -82,7 +82,7 @@ allocate_trampoline_page (void)
 {
   void *page;
 
-#if defined(__linux__)
+#if defined(__linux__) || defined(__gnu_hurd__)
   page = mmap (0, getpagesize (), PROT_WRITE | PROT_EXEC,
 	       MAP_ANON | MAP_PRIVATE, 0, 0);
 #elif __APPLE__
-- 
2.44.0