Merge commit 'origin/unwind'

* commit 'origin/unwind':
  Fixes for 2.6.25 pt_regs changes.
  Include string.h
  Change stap to get kernel symbols from debuginfo and
  reincarnate vim/ directory in this branch to match master
  Add new define STP_USE_DWARF_UNWINDER which is set based on which archs
  Remove misleading error message.
  Support for kernels built with CONFIG_FRAME_POINTER
  Fix regression.
  dded _stp_read_address() and changed code to use it.
  kretprobe trampoline fixes
  i386 fixes.
  control.c (_stp_ctl_write_dbug): Insert missing break.
  32-bit fixes
  Cleanup.
  2008-03-23  Frank Ch. Eigler  <fche@elastic.org>
  2008-03-23  Frank Ch. Eigler  <fche@elastic.org>
  2008-03-21  Eugene Teo  <eugeneteo@kernel.sg>
  add (back) runtime/unwind files
  * clarify utility of epilogue-type probe aliases in documentation
  rebased unwind_branch on top of current master

1 files changed, 30 insertions, 6 deletions

diff --git a/runtime/stack-x86_64.c b/runtime/stack-x86_64.c
index 186b2ad4..ae8e446d 100644
--- a/runtime/stack-x86_64.c
+++ b/runtime/stack-x86_64.c
@@ -1,6 +1,6 @@
 /* -*- linux-c -*-
  * x86_64 stack tracing functions
- * Copyright (C) 2005, 2006, 2007 Red Hat Inc.
+ * Copyright (C) 2005-2008 Red Hat Inc.
  *
  * This file is part of systemtap, and is free software.  You can
  * redistribute it and/or modify it under the terms of the GNU General
@@ -8,13 +8,37 @@
  * later version.
  */
 
-static void __stp_stack_print (struct pt_regs *regs, int verbose, int levels)
+/* DWARF unwinder failed.  Just dump intereting addresses on kernel stack. */
+static void _stp_stack_print_fallback(unsigned long stack, int verbose)
 {
-	unsigned long *stack = (unsigned long *)REG_SP(regs);
 	unsigned long addr;
+	while (stack & (THREAD_SIZE - 1)) {
+		if (unlikely(_stp_read_address(addr, (unsigned long *)stack, KERNEL_DS))) {
+			/* cannot access stack.  give up. */
+			return;
+		}
+		_stp_func_print(addr, verbose, 0);
+		stack++;
+	}
+}
+
+static void __stp_stack_print(struct pt_regs *regs, int verbose, int levels)
+{
+	// FIXME: large stack allocation
+	struct unwind_frame_info info;
+	arch_unw_init_frame_info(&info, regs);
 
-	while ((long)stack & (THREAD_SIZE-1)) {
-		addr = *stack++;
-		_stp_func_print(addr, verbose, 1);
+	while (!arch_unw_user_mode(&info)) {
+		int ret = unwind(&info);
+		dbug_unwind(1, "ret=%d PC=%lx SP=%lx\n", ret, UNW_PC(&info), UNW_SP(&info));
+		if (ret == 0) {
+			_stp_func_print(UNW_PC(&info), verbose, 1);
+			continue;
+		}
+		/* If an error happened or we hit a kretprobe trampoline, use fallback backtrace */
+		/* FIXME: is there a way to unwind across kretprobe trampolines? */
+		if (ret < 0 || (ret > 0 && UNW_PC(&info) == _stp_kretprobe_trampoline))
+			_stp_stack_print_fallback(UNW_SP(&info), verbose);
+		break;
 	}
 }