[PATCH][AARCH64][BZ #16850]Increase MINSIGSTKSZ & SIGSTKSZ

[Renlin Li <renlin dot li at arm dot com>]

Hi all,

This patch duplicates sysdeps/unix/sysv/linux/bits/sigstack.h into 
sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h and modifies only 
SIGSTCKSZ and MINSIGSTKSZ.

The ucontext_t is 4560 bytes, siginfo_t is 128 bytes. The required 
sigframe is far larger than the current default MINSIGSTKSZ (which is 
2048). Thus, I increase MINSIGSTKSZ to 8192, and adjust SIGSTCKSZ 
accordingly.

Glibc has been build and test on the model, no new issues.

Okay to commit?

ChangeLog:

2014-11-14  Renlin Li  <Renlin.Li@arm.com>
    [BZ #16850]
    * sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h: New.

diff --git a/NEWS b/NEWS
index c582c8e..bd02fa9 100644
--- a/NEWS
+++ b/NEWS
@@ -9,10 +9,10 @@ Version 2.21
 
 * The following bugs are resolved with this release:
 
-  6652, 12926, 14132, 14138, 14171, 15215, 15884, 17266, 17344, 17363,
-  17370, 17371, 17411, 17460, 17475, 17485, 17501, 17506, 17508, 17522,
-  17555, 17570, 17571, 17572, 17573, 17574, 17582, 17583, 17584, 17585,
-  17589, 17594.
+  6652, 12926, 14132, 14138, 14171, 15215, 15884, 16850, 17266, 17344,
+  17363, 17370, 17371, 17411, 17460, 17475, 17485, 17501, 17506, 17508,
+  17522, 17555, 17570, 17571, 17572, 17573, 17574, 17582, 17583, 17584,
+  17585, 17589, 17594.
 
 * New locales: tu_IN, bh_IN.
 
diff --git a/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h b/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
new file mode 100644
index 0000000..a73c56e
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
@@ -0,0 +1,54 @@
+/* sigstack, sigaltstack definitions.
+   Copyright (C) 1998-2014 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 _SIGNAL_H
+# error "Never include this file directly.  Use <signal.h> instead"
+#endif
+
+
+/* Structure describing a signal stack (obsolete).  */
+struct sigstack
+  {
+    void *ss_sp;		/* Signal stack pointer.  */
+    int ss_onstack;		/* Nonzero if executing on this stack.  */
+  };
+
+
+/* Possible values for `ss_flags.'.  */
+enum
+{
+  SS_ONSTACK = 1,
+#define SS_ONSTACK	SS_ONSTACK
+  SS_DISABLE
+#define SS_DISABLE	SS_DISABLE
+};
+
+/* Minimum stack size for a signal handler.  */
+#define MINSIGSTKSZ	8192
+
+/* System default stack size.  */
+#define SIGSTKSZ	16384
+
+
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    void *ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;