Add backtrace for m68k

ports/ChangeLog.m68k

@@ -1,5 +1,7 @@
 2013-01-19  Andreas Schwab  <schwab@linux-m68k.org>
 
+	* sysdeps/m68k/backtrace.c: New file.
+
 	* sysdeps/unix/sysv/linux/m68k/nptl/not-cancel.h: New file.
 	* sysdeps/unix/sysv/linux/m68k/syscalls.list: Add waitpid.
 

ports/sysdeps/m68k/backtrace.c

@@ -0,0 +1,159 @@
+/* Return backtrace of current program state.
+   Copyright (C) 2013 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 <bits/libc-lock.h>
+#include <dlfcn.h>
+#include <execinfo.h>
+#include <stdlib.h>
+#include <unwind.h>
+
+struct trace_arg
+{
+  void **array;
+  int cnt, size;
+  void *lastfp, *lastsp;
+};
+
+#ifdef SHARED
+static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
+static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
+static _Unwind_Ptr (*unwind_getcfa) (struct _Unwind_Context *);
+static _Unwind_Ptr (*unwind_getgr) (struct _Unwind_Context *, int);
+static void *libgcc_handle;
+
+static void
+init (void)
+{
+  libgcc_handle = __libc_dlopen ("libgcc_s.so.2");
+
+  if (libgcc_handle == NULL)
+    return;
+
+  unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
+  unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP");
+  unwind_getcfa = __libc_dlsym (libgcc_handle, "_Unwind_GetCFA");
+  unwind_getgr = __libc_dlsym (libgcc_handle, "_Unwind_GetGR");
+  if (unwind_getip == NULL || unwind_getgr == NULL || unwind_getcfa == NULL)
+    {
+      unwind_backtrace = NULL;
+      __libc_dlclose (libgcc_handle);
+      libgcc_handle = NULL;
+    }
+}
+#else
+# define unwind_backtrace _Unwind_Backtrace
+# define unwind_getip _Unwind_GetIP
+# define unwind_getcfa _Unwind_GetCFA
+# define unwind_getgr _Unwind_GetGR
+#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;
+
+  /* %fp is DWARF2 register 14 on M68K.  */
+  arg->lastfp = (void *) unwind_getgr (ctx, 14);
+  arg->lastsp = (void *) unwind_getcfa (ctx);
+  return _URC_NO_REASON;
+}
+
+
+/* This is a global variable set at program start time.  It marks the
+   highest used stack address.  */
+extern void *__libc_stack_end;
+
+
+/* This is the stack layout we see with every stack frame
+   if not compiled without frame pointer.
+
+           +-----------------+       +-----------------+
+    %fp -> | %fp last frame--------> | %fp last frame--->...
+           |                 |       |                 |
+           | return address  |       | return address  |
+           +-----------------+       +-----------------+
+
+   First try as far to get as far as possible using
+   _Unwind_Backtrace which handles -fomit-frame-pointer
+   as well, but requires .eh_frame info.  Then fall back to
+   walking the stack manually.  */
+
+struct layout
+{
+  struct layout *fp;
+  void *ret;
+};
+
+
+int
+__backtrace (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;
+  else if (arg.cnt < size)
+    {
+      struct layout *fp = (struct layout *) arg.lastfp;
+
+      while (arg.cnt < size)
+	{
+	  /* Check for out of range.  */
+	  if ((void *) fp < arg.lastsp || (void *) fp > __libc_stack_end
+	      || ((long) fp & 1))
+	    break;
+
+	  array[arg.cnt++] = fp->ret;
+	  fp = fp->fp;
+	}
+    }
+  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