Move arm from ports to libc.

I've moved the ARM port from ports to the main sysdeps hierarchy.
Beyond the README update, the move of the files was simply

git mv ports/sysdeps/arm sysdeps/arm
git mv ports/sysdeps/unix/arm sysdeps/unix/arm
git mv ports/sysdeps/unix/sysv/linux/arm sysdeps/unix/sysv/linux/arm

and in addition to the ChangeLog entries here, I put a note at the top
of ports/ChangeLog.arm similar to that at the top of
ChangeLog.powerpc.  There is deliberately no NEWS change, as I think
it makes the most sense to put in a general note above all ports
having moved if we can achieve that for 2.20.

Tested that disassembly of installed shared libraries for arm is the
same before and after this patch, except for data (not instructions)
in ld.so (there are assertions in sysdeps/arm/dl-machine.h, and the
path by which that file is found, and so by which it appears in the
assertion message, changes as a result of the move).

	* sysdeps/arm: Move directory from ports/sysdeps/arm.
	* sysdeps/unix/arm: Move directory from ports/sysdeps/unix/arm.
	* sysdeps/unix/sysv/linux/arm: Move directory from
	ports/sysdeps/unix/sysv/linux/arm.
	* README: Update listing for arm-*-linux-gnueabi.

ports/ChangeLog.arm:
	* sysdeps/arm: Move directory to ../sysdeps/arm.
	* sysdeps/unix/arm: Move directory to ../sysdeps.arm.
	* sysdeps/unix/sysv/linux/arm: Move directory to
	../sysdeps/unix/sysv/linux/arm.

1 files changed, 125 insertions, 0 deletions

diff --git a/sysdeps/arm/backtrace.c b/sysdeps/arm/backtrace.c
new file mode 100644
index 0000000000..15ba506411
--- /dev/null
+++ b/sysdeps/arm/backtrace.c
@@ -0,0 +1,125 @@
+/* Return backtrace of current program state.
+   Copyright (C) 2008-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Kazu Hirata <kazu@codesourcery.com>, 2008.
+
+   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 <bits/libc-lock.h>
+#include <dlfcn.h>
+#include <execinfo.h>
+#include <stdlib.h>
+#include <unwind.h>
+
+struct trace_arg
+{
+  void **array;
+  int cnt, size;
+};
+
+#ifdef SHARED
+static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
+static _Unwind_VRS_Result (*unwind_vrs_get) (_Unwind_Context *,
+					     _Unwind_VRS_RegClass,
+					     _uw,
+					     _Unwind_VRS_DataRepresentation,
+					     void *);
+
+static void *libgcc_handle;
+
+static void
+init (void)
+{
+  libgcc_handle = __libc_dlopen ("libgcc_s.so.1");
+
+  if (libgcc_handle == NULL)
+    return;
+
+  unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
+  unwind_vrs_get = __libc_dlsym (libgcc_handle, "_Unwind_VRS_Get");
+  if (unwind_vrs_get == NULL)
+    unwind_backtrace = NULL;
+}
+
+/* This function is identical to "_Unwind_GetGR", except that it uses
+   "unwind_vrs_get" instead of "_Unwind_VRS_Get".  */
+static inline _Unwind_Word
+unwind_getgr (_Unwind_Context *context, int regno)
+{
+  _uw val;
+  unwind_vrs_get (context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val);
+  return val;
+}
+
+/* This macro is identical to the _Unwind_GetIP macro, except that it
+   uses "unwind_getgr" instead of "_Unwind_GetGR".  */
+# define unwind_getip(context) \
+  (unwind_getgr (context, 15) & ~(_Unwind_Word)1)
+#else
+# define unwind_backtrace _Unwind_Backtrace
+# define unwind_getip _Unwind_GetIP
+#endif
+
+static _Unwind_Reason_Code
+backtrace_helper (struct _Unwind_Context *ctx, void *a)
+{
+  struct trace_arg *arg = a;
+
+  /* We are first called with address in the __backtrace function.
+     Skip it.  */
+  if (arg->cnt != -1)
+    arg->array[arg->cnt] = (void *) unwind_getip (ctx);
+  if (++arg->cnt == arg->size)
+    return _URC_END_OF_STACK;
+  return _URC_NO_REASON;
+}
+
+int
+__backtrace (array, size)
+     void **array;
+     int size;
+{
+  struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+#ifdef SHARED
+  __libc_once_define (static, once);
+
+  __libc_once (once, init);
+  if (unwind_backtrace == NULL)
+    return 0;
+#endif
+
+  if (size >= 1)
+    unwind_backtrace (backtrace_helper, &arg);
+
+  if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
+    --arg.cnt;
+  return arg.cnt != -1 ? arg.cnt : 0;
+}
+weak_alias (__backtrace, backtrace)
+libc_hidden_def (__backtrace)
+
+
+#ifdef SHARED
+/* Free all resources if necessary.  */
+libc_freeres_fn (free_mem)
+{
+  unwind_backtrace = NULL;
+  if (libgcc_handle != NULL)
+    {
+      __libc_dlclose (libgcc_handle);
+      libgcc_handle = NULL;
+    }
+}
+#endif