x86_64: Use shadow stack for backtrace implementationfw/x86-shstk-backtrace

Test failures:

FAIL: debug/tst-backtrace4
FAIL: misc/tst-sigcontext-get_pc

The return address of signal handlers is not on the shadow stack.

1 files changed, 25 insertions, 0 deletions

diff --git a/sysdeps/generic/arch_backtrace.h b/sysdeps/generic/arch_backtrace.h
new file mode 100644
index 0000000..ebdffd7
--- /dev/null
+++ b/sysdeps/generic/arch_backtrace.h
@@ -0,0 +1,25 @@
+/* Architecture-specific backtrace implementation.  Generic version.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* The generic implementation always uses falls back to the libgcc
+   unwinder.  */
+static inline __always_inline int
+__arch_backtrace (void **array, int size)
+{
+  return -1;
+}