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| author | H.J. Lu <hjl.tools@gmail.com> | 2018-07-24 07:55:35 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2018-07-24 07:55:47 -0700 |
| commit | e27f41ba2b6101be1a511905bff5502ffd23828b (patch) | |
| tree | f7bd74631da12cc22e2dc5f6556a9ea2b45de5f0 /bits | |
| parent | 21526a507df8f1b2e37492193a754534d8938c0b (diff) | |
Add <bits/indirect-return.h>
Add <bits/indirect-return.h> and include it in <ucontext.h>.
__INDIRECT_RETURN defined in <bits/indirect-return.h> indicates if
swapcontext requires special compiler treatment. The default
__INDIRECT_RETURN is empty.
On x86, when shadow stack is enabled, __INDIRECT_RETURN is defined
with indirect_return attribute, which has been added to GCC 9, to
indicate that swapcontext returns via indirect branch. Otherwise
__INDIRECT_RETURN is defined with returns_twice attribute.
When shadow stack is enabled, remove always_inline attribute from
prepare_test_buffer in string/tst-xbzero-opt.c to avoid:
tst-xbzero-opt.c: In function ‘prepare_test_buffer’:
tst-xbzero-opt.c:105:1: error: function ‘prepare_test_buffer’ can never be inlined because it uses setjmp
prepare_test_buffer (unsigned char *buf)
when indirect_return attribute isn't available.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* bits/indirect-return.h: New file.
* misc/sys/cdefs.h (__glibc_has_attribute): New.
* sysdeps/x86/bits/indirect-return.h: Likewise.
* stdlib/Makefile (headers): Add bits/indirect-return.h.
* stdlib/ucontext.h: Include <bits/indirect-return.h>.
(swapcontext): Add __INDIRECT_RETURN.
* string/tst-xbzero-opt.c (ALWAYS_INLINE): New.
(prepare_test_buffer): Use it.
Diffstat (limited to 'bits')
| -rw-r--r-- | bits/indirect-return.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/bits/indirect-return.h b/bits/indirect-return.h new file mode 100644 index 0000000000..47f6f15a6e --- /dev/null +++ b/bits/indirect-return.h @@ -0,0 +1,25 @@ +/* Definition of __INDIRECT_RETURN. Generic version. + Copyright (C) 2018 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 + <http://www.gnu.org/licenses/>. */ + +#ifndef _UCONTEXT_H +# error "Never include <bits/indirect-return.h> directly; use <ucontext.h> instead." +#endif + +/* __INDIRECT_RETURN is used on swapcontext to indicate if it requires + special compiler treatment. */ +#define __INDIRECT_RETURN |