[patches] Fix Thumb-2 aio_suspend cancellation

["Joseph S. Myers" <joseph@xxxxxxxxxxxxxxxx>]

I've applied this patch to trunk, 2.9 and 2.8 branches to fix cancellation 
in aio_suspend for Thumb-2 (testcases nptl/tst-cancel17 and 
nptl/tst-cancelx17).  The problem with cancellation in this function and 
the fix used are explained in the comment added.

Index: sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h
===================================================================
--- sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h	(revision 0)
+++ sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h	(revision 0)
@@ -0,0 +1,52 @@
+/* Copyright (C) 2008 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include_next <aio_misc.h>
+
+#ifdef __thumb2__
+
+#include <errno.h>
+
+/* The Thumb-2 definition of INTERNAL_SYSCALL_RAW has to hide the use
+   of r7 from the compiler because it cannot handle asm clobbering the
+   hard frame pointer.  In aio_suspend, GCC does not eliminate the
+   hard frame pointer because the function uses variable-length
+   arrays, so it generates unwind information using r7 as virtual
+   stack pointer.  During system calls, when r7 has been saved on the
+   stack, this means the unwind information is invalid.  Without extra
+   unwind directives, which would need to cause unwind information for
+   the asm to be generated separately from that for the parts of the
+   function before and after the asm (with three index table entries),
+   it is not possible to represent any temporary change to the virtual
+   stack pointer.  Instead, we move the problematic system calls out
+   of line into a function that does not require a frame pointer.  */
+
+static __attribute_noinline__ void
+aio_misc_wait (int *resultp,
+	       volatile int *futexp,
+	       const struct timespec *timeout,
+	       int cancel)
+{
+  AIO_MISC_WAIT (*resultp, *futexp, timeout, cancel);
+}
+
+#undef AIO_MISC_WAIT
+#define AIO_MISC_WAIT(result, futex, timeout, cancel)	\
+  aio_misc_wait (&result, &futex, timeout, cancel)
+
+#endif
Index: ChangeLog.eglibc
===================================================================
--- ChangeLog.eglibc	(revision 7416)
+++ ChangeLog.eglibc	(working copy)
@@ -1,3 +1,7 @@
+2008-11-27  Joseph Myers  <joseph@xxxxxxxxxxxxxxxx>
+
+	* sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h: New.
+
 2008-11-25  Joseph Myers  <joseph@xxxxxxxxxxxxxxxx>
 
 	* sysdeps/unix/sysv/linux/arm/sysdep.h (LOAD_ARGS_1, LOAD_ARGS_2,

-- 
Joseph S. Myers
joseph@xxxxxxxxxxxxxxxx