Let x86 stackwalker scan stack in cases where program evaluation fails. Original patch by Jeff Muizelaar <jmuizelaar@mozilla.com> with some changes by me. r=mento at http://breakpad.appspot.com/32003/show

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@409 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/google_breakpad/processor/stack_frame_cpu.h

@@ -58,7 +58,23 @@ struct StackFrameX86 : public StackFrame {
     CONTEXT_VALID_ALL  = -1
   };
 
-  StackFrameX86() : context(), context_validity(CONTEXT_VALID_NONE) {}
+  // Indicates how well we trust the instruction pointer we derived
+  // during stack walking. Since the stack walker can resort to
+  // stack scanning, we can wind up with dubious frames.
+  // In rough order of "trust metric".
+  enum FrameTrust {
+    FRAME_TRUST_NONE,     // Unknown
+    FRAME_TRUST_SCAN,     // Scanned the stack, found this
+    FRAME_TRUST_CFI_SCAN, // Scanned the stack using call frame info, found this
+    FRAME_TRUST_FP,       // Derived from frame pointer
+    FRAME_TRUST_CFI,      // Derived from call frame info
+    FRAME_TRUST_CONTEXT   // Given as instruction pointer in a context
+  };
+
+ StackFrameX86()
+     : context(),
+       context_validity(CONTEXT_VALID_NONE),
+       trust(FRAME_TRUST_NONE) {}
 
   // Register state.  This is only fully valid for the topmost frame in a
   // stack.  In other frames, the values of nonvolatile registers may be
@@ -70,6 +86,10 @@ struct StackFrameX86 : public StackFrame {
   // the OR operator doesn't work well with enumerated types.  This indicates
   // which fields in context are valid.
   int context_validity;
+  
+  // Amount of trust the stack walker has in the instruction pointer
+  // of this frame.
+  FrameTrust trust;
 };
 
 struct StackFramePPC : public StackFrame {

src/google_breakpad/processor/stackwalker.h

@@ -42,6 +42,7 @@
 #define GOOGLE_BREAKPAD_PROCESSOR_STACKWALKER_H__
 
 #include <vector>
+#include "google_breakpad/common/breakpad_types.h"
 
 namespace google_breakpad {
 
@@ -95,6 +96,16 @@ class Stackwalker {
               SymbolSupplier *supplier,
               SourceLineResolverInterface *resolver);
 
+  // This can be used to filter out potential return addresses when
+  // the stack walker resorts to stack scanning.
+  // Returns true if any of:
+  // * This address is within a loaded module, but we don't have symbols
+  //   for that module.
+  // * This address is within a loaded module for which we have symbols,
+  //   and falls inside a function in that module.
+  // Returns false otherwise.
+  bool InstructionAddressSeemsValid(u_int64_t address);
+
   // Information about the system that produced the minidump.  Subclasses
   // and the SymbolSupplier may find this information useful.
   const SystemInfo *system_info_;