Linux/x86: Update cancel_jmp_buf to match __jmp_buf_tag [BZ #22563]

On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer
to support shadow stack in Intel Control-flow Enforcemen Technology.
Since the cancel_jmp_buf array is passed to setjmp and longjmp by
casting it to pointer to struct __jmp_buf_tag, it should be as large
as struct __jmp_buf_tag.  Otherwise when shadow stack is enabled,
setjmp and longjmp will write and read beyond cancel_jmp_buf when saving
and restoring shadow stack pointer.

This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct
__cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to
cancel_jmp_buf.

Tested natively on i386, x86_64 and x32.  Tested hppa-linux-gnu with
build-many-glibcs.py.

	[BZ #22563]
	* bits/types/__cancel_jmp_buf_tag.h: New file.
	* sysdeps/unix/sysv/linux/x86/bits/types/__cancel_jmp_buf_tag.h
	* sysdeps/unix/sysv/linux/x86/pthreaddef.h: Likewise.
	* sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h: Likewise.
	* nptl/Makefile (headers): Add
	bits/types/__cancel_jmp_buf_tag.h.
	* nptl/descr.h [NEED_SAVED_MASK_IN_CANCEL_JMP_BUF]
	(pthread_unwind_buf): Add saved_mask to cancel_jmp_buf.
	* sysdeps/nptl/pthread.h: Include
	<bits/types/__cancel_jmp_buf_tag.h>.
	(__pthread_unwind_buf_t): Use struct __cancel_jmp_buf_tag with
	__cancel_jmp_buf.
	* sysdeps/unix/sysv/linux/hppa/pthread.h: Likewise.

3 files changed, 89 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/x86/bits/types/__cancel_jmp_buf_tag.h b/sysdeps/unix/sysv/linux/x86/bits/types/__cancel_jmp_buf_tag.h
new file mode 100644
index 0000000000..830a6ec90c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/bits/types/__cancel_jmp_buf_tag.h
@@ -0,0 +1,31 @@
+/* Define struct __cancel_jmp_buf_tag.
+   Copyright (C) 2017 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 ____cancel_jmp_buf_tag_defined
+#define ____cancel_jmp_buf_tag_defined 1
+
+#include <bits/types/__sigset_t.h>
+
+struct __cancel_jmp_buf_tag
+  {
+    __jmp_buf __cancel_jmp_buf;
+    int __mask_was_saved;
+    __sigset_t __saved_mask;
+  };
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h b/sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h
new file mode 100644
index 0000000000..8c36ba3a5d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h
@@ -0,0 +1,36 @@
+/* Internal pthread header.  Linux/x86 version.
+   Copyright (C) 2017 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/>.  */
+
+#include_next <nptl/pthreadP.h>
+
+#ifndef _PTHREADP_H_X86
+#define _PTHREADP_H_X86 1
+
+extern struct pthread_unwind_buf ____pthread_unwind_buf_private;
+
+_Static_assert (sizeof (____pthread_unwind_buf_private.cancel_jmp_buf)
+		>= sizeof (struct __jmp_buf_tag),
+		"size of cancel_jmp_buf < sizeof __jmp_buf_tag");
+
+extern __pthread_unwind_buf_t ____pthread_unwind_buf;
+
+_Static_assert (sizeof (____pthread_unwind_buf.__cancel_jmp_buf)
+		>= sizeof (struct __jmp_buf_tag),
+		"size of __cancel_jmp_buf < sizeof __jmp_buf_tag");
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/x86/pthreaddef.h b/sysdeps/unix/sysv/linux/x86/pthreaddef.h
new file mode 100644
index 0000000000..89d19d60a1
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/pthreaddef.h
@@ -0,0 +1,22 @@
+/* Pthread macros.  Linux/x86 version.
+   Copyright (C) 2017 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/>.  */
+
+#include_next <pthreaddef.h>
+
+/* Need saved_mask in cancel_jmp_buf.  */
+#define NEED_SAVED_MASK_IN_CANCEL_JMP_BUF 1