Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 131 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/powerpc/powerpc32/backtrace.c b/REORG.TODO/sysdeps/powerpc/powerpc32/backtrace.c
new file mode 100644
index 0000000000..394062136c
--- /dev/null
+++ b/REORG.TODO/sysdeps/powerpc/powerpc32/backtrace.c
@@ -0,0 +1,131 @@
+/* Return backtrace of current program state.
+   Copyright (C) 1998-2017 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 <execinfo.h>
+#include <stddef.h>
+#include <string.h>
+#include <signal.h>
+#include <libc-vdso.h>
+
+/* This is the stack layout we see with every stack frame.
+   Note that every routine is required by the ABI to lay out the stack
+   like this.
+
+            +----------------+        +-----------------+
+    %r1  -> | %r1 last frame--------> | %r1 last frame--->...  --> NULL
+            |                |        |                 |
+            | (unused)       |        | return address  |
+            +----------------+        +-----------------+
+*/
+struct layout
+{
+  struct layout *next;
+  void *return_address;
+};
+
+#define SIGNAL_FRAMESIZE 64
+
+/* Since the signal handler is just like any other function it needs to
+   save/restore its LR and it will save it into callers stack frame.
+   Since a signal handler doesn't have a caller, the kernel creates a
+   dummy frame to make it look like it has a caller.  */
+struct signal_frame_32 {
+  char               dummy[SIGNAL_FRAMESIZE];
+  struct sigcontext  sctx;
+  mcontext_t         mctx;
+  /* We don't care about the rest, since IP value is at 'mctx' field.  */
+};
+
+static inline int
+is_sigtramp_address (void *nip)
+{
+#ifdef SHARED
+  if (nip == VDSO_SYMBOL (sigtramp32))
+    return 1;
+#endif
+  return 0;
+}
+
+struct rt_signal_frame_32 {
+  char               dummy[SIGNAL_FRAMESIZE + 16];
+  siginfo_t          info;
+  struct ucontext    uc;
+  /* We don't care about the rest, since IP value is at 'uc' field.  */
+};
+
+static inline int
+is_sigtramp_address_rt (void * nip)
+{
+#ifdef SHARED
+  if (nip == VDSO_SYMBOL (sigtramp_rt32))
+    return 1;
+#endif
+  return 0;
+}
+
+int
+__backtrace (void **array, int size)
+{
+  struct layout *current;
+  int count;
+
+  /* Force gcc to spill LR.  */
+  asm volatile ("" : "=l"(current));
+
+  /* Get the address on top-of-stack.  */
+  asm volatile ("lwz %0,0(1)" : "=r"(current));
+
+  for (				count = 0;
+       current != NULL && 	count < size;
+       current = current->next, count++)
+    {
+      gregset_t *gregset = NULL;
+
+      array[count] = current->return_address;
+
+      /* Check if the symbol is the signal trampoline and get the interrupted
+       * symbol address from the trampoline saved area.  */
+      if (is_sigtramp_address (current->return_address))
+	{
+	  struct signal_frame_32 *sigframe =
+	    (struct signal_frame_32*) current;
+          gregset = &sigframe->mctx.gregs;
+        }
+      else if (is_sigtramp_address_rt (current->return_address))
+	{
+	  struct rt_signal_frame_32 *sigframe =
+            (struct rt_signal_frame_32*) current;
+          gregset = &sigframe->uc.uc_mcontext.uc_regs->gregs;
+        }
+      if (gregset)
+	{
+	  array[++count] = (void*)((*gregset)[PT_NIP]);
+	  current = (void*)((*gregset)[PT_R1]);
+	}
+    }
+
+  /* It's possible the second-last stack frame can't return
+     (that is, it's __libc_start_main), in which case
+     the CRT startup code will have set its LR to 'NULL'.  */
+  if (count > 0 && array[count-1] == NULL)
+    count--;
+
+  return count;
+}
+weak_alias (__backtrace, backtrace)
+libc_hidden_def (__backtrace)