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* [glibc/arm/gcs] aarch64: mark swapcontext with indirect_return
@ 2024-02-14 15:06 Szabolcs Nagy
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From: Szabolcs Nagy @ 2024-02-14 15:06 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=99f884d57f17afea877006284f469747711e1d51
commit 99f884d57f17afea877006284f469747711e1d51
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Thu Dec 28 15:53:38 2023 +0000
aarch64: mark swapcontext with indirect_return
Diff:
---
sysdeps/aarch64/bits/indirect-return.h | 36 ++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
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
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