diff mbox series

[RFC,v2,08/22] aarch64: Mark swapcontext with indirect_return

Message ID 20241018095845.2955276-1-yury.khrustalev@arm.com
State New
Headers show
Series aarch64: Add support for Guarded Control Stack extension | expand

Commit Message

Yury Khrustalev Oct. 18, 2024, 9:58 a.m. UTC 
From: Szabolcs Nagy <szabolcs.nagy@arm.com>

---
 sysdeps/aarch64/bits/indirect-return.h | 36 ++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 sysdeps/aarch64/bits/indirect-return.h
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Patch

diff --git a/sysdeps/aarch64/bits/indirect-return.h b/sysdeps/aarch64/bits/indirect-return.h
new file mode 100644
index 0000000000..99905f21fa
--- /dev/null
+++ b/sysdeps/aarch64/bits/indirect-return.h
@@ -0,0 +1,36 @@ 
+/* Definition of __INDIRECT_RETURN.  AArch64 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/>.  */
+
+#ifndef _UCONTEXT_H
+# error "Never include <bits/indirect-return.h> directly; use <ucontext.h> instead."
+#endif
+
+/* __INDIRECT_RETURN indicates that swapcontext may return via
+   an indirect branch.  This happens when GCS is enabled, so
+   add the attribute if available, otherwise returns_twice has
+   a similar effect, but it prevents some code transformations
+   that can cause build failures in some rare cases so it is
+   only used when GCS is enabled.  */
+#if __glibc_has_attribute (__indirect_return__)
+# define __INDIRECT_RETURN __attribute__ ((__indirect_return__))
+#elif __glibc_has_attribute (__returns_twice__) \
+      && defined __ARM_FEATURE_GCS_DEFAULT
+# define __INDIRECT_RETURN __attribute__ ((__returns_twice__))
+#else
+# define __INDIRECT_RETURN
+#endif