Bug 724079. Add an internal stackwalk API. r=ehsan

This will be used by the profiler to be able to unwind arbitrary threads.

xpcom/base/Makefile.in

@@ -103,6 +103,7 @@ EXPORTS_mozilla = \
 	MapsMemoryReporter.h \
 	ClearOnShutdown.h \
 	AvailableMemoryTracker.h \
+	StackWalk.h \
 	$(NULL)
 
 ifeq (windows,$(MOZ_WIDGET_TOOLKIT))

xpcom/base/StackWalk.h

@@ -0,0 +1,52 @@
+/* vim: set shiftwidth=4 tabstop=8 autoindent cindent expandtab: */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Initial Developer of the Original Code is the Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2011
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Jeff Muizelaar <jmuizelaar@mozilla.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+/* API for getting a stack trace of the C/C++ */
+
+#ifndef StackWalk_h_
+#define StackWalk_h_
+
+// XXX: it would be nice to eventually remove this header dependency on nsStackWalk.h
+#include "nsStackWalk.h"
+
+namespace mozilla {
+
+nsresult
+FramePointerStackWalk(NS_WalkStackCallback aCallback, PRUint32 aSkipFrames,
+                      void *aClosure, void **bp);
+
+}
+
+#endif /* !defined(StackWalk_h_) */

xpcom/base/nsStackWalk.cpp

@@ -41,11 +41,14 @@
 /* API for getting a stack trace of the C/C++ stack on the current thread */
 
 #include "mozilla/Util.h"
+#include "mozilla/StackWalk.h"
 #include "nsDebug.h"
 #include "nsStackWalkPrivate.h"
 
 #include "nsStackWalk.h"
 
+using namespace mozilla;
+
 // The presence of this address is the stack must stop the stack walk. If
 // there is no such address, the structure will be {NULL, true}.
 struct CriticalAddress {
@@ -215,8 +218,6 @@ StackWalkInitCriticalAddress()
 #endif
 #endif
 
-using namespace mozilla;
-
 // Define these as static pointers so that we can load the DLL on the
 // fly (and not introduce a link-time dependency on it). Tip o' the
 // hat to Matt Pietrick for this idea. See:
@@ -1572,9 +1573,6 @@ NS_FormatCodeAddressDetails(void *aPC, const nsCodeAddressDetails *aDetails,
 
 #else // not __sun-specific
 
-#define X86_OR_PPC (defined(__i386) || defined(PPC) || defined(__ppc__))
-#if X86_OR_PPC && (NSSTACKWALK_SUPPORTS_MACOSX || NSSTACKWALK_SUPPORTS_LINUX) // i386 or PPC Linux or Mac stackwalking code
-
 #if __GLIBC__ > 2 || __GLIBC_MINOR > 1
 #define HAVE___LIBC_STACK_END 1
 #else
@@ -1584,26 +1582,13 @@ NS_FormatCodeAddressDetails(void *aPC, const nsCodeAddressDetails *aDetails,
 #if HAVE___LIBC_STACK_END
 extern void *__libc_stack_end; // from ld-linux.so
 #endif
-
-EXPORT_XPCOM_API(nsresult)
-NS_StackWalk(NS_WalkStackCallback aCallback, PRUint32 aSkipFrames,
-             void *aClosure, uintptr_t aThread)
+namespace mozilla {
+nsresult
+FramePointerStackWalk(NS_WalkStackCallback aCallback, PRUint32 aSkipFrames,
+                      void *aClosure, void **bp)
 {
-  MOZ_ASSERT(gCriticalAddress.mInit);
-  MOZ_ASSERT(!aThread);
   // Stack walking code courtesy Kipp's "leaky".
 
-  // Get the frame pointer
-  void **bp;
-#if defined(__i386) 
-  __asm__( "movl %%ebp, %0" : "=g"(bp));
-#else
-  // It would be nice if this worked uniformly, but at least on i386 and
-  // x86_64, it stopped working with gcc 4.1, because it points to the
-  // end of the saved registers instead of the start.
-  bp = (void**) __builtin_frame_address(0);
-#endif
-
   int skip = aSkipFrames;
   while (1) {
     void **next = (void**)*bp;
@@ -1636,6 +1621,33 @@ NS_StackWalk(NS_WalkStackCallback aCallback, PRUint32 aSkipFrames,
   return NS_OK;
 }
 
+}
+
+#define X86_OR_PPC (defined(__i386) || defined(PPC) || defined(__ppc__))
+#if X86_OR_PPC && (NSSTACKWALK_SUPPORTS_MACOSX || NSSTACKWALK_SUPPORTS_LINUX) // i386 or PPC Linux or Mac stackwalking code
+
+EXPORT_XPCOM_API(nsresult)
+NS_StackWalk(NS_WalkStackCallback aCallback, PRUint32 aSkipFrames,
+             void *aClosure, uintptr_t aThread)
+{
+  MOZ_ASSERT(gCriticalAddress.mInit);
+  MOZ_ASSERT(!aThread);
+
+  // Get the frame pointer
+  void **bp;
+#if defined(__i386) 
+  __asm__( "movl %%ebp, %0" : "=g"(bp));
+#else
+  // It would be nice if this worked uniformly, but at least on i386 and
+  // x86_64, it stopped working with gcc 4.1, because it points to the
+  // end of the saved registers instead of the start.
+  bp = (void**) __builtin_frame_address(0);
+#endif
+  return FramePointerStackWalk(aCallback, aSkipFrames,
+                               aClosure, bp);
+
+}
+
 #elif defined(HAVE__UNWIND_BACKTRACE)
 
 // libgcc_s.so symbols _Unwind_Backtrace@@GCC_3.3 and _Unwind_GetIP@@GCC_3.0