Refactor some bits of StackWalkerX86 / StackFrameX86 out into their respective parent classes so they can be used by other architecture implementations.

R=jimb at http://breakpad.appspot.com/205001/show

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@703 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/google_breakpad/processor/stack_frame.h

@@ -40,6 +40,19 @@ class CodeModule;
 using std::string;
 
 struct StackFrame {
+  // Indicates how well the instruction pointer derived during
+  // stack walking is trusted. Since the stack walker can resort to
+  // stack scanning, it 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
+  };
+
   StackFrame()
       : instruction(),
         module(NULL),
@@ -47,9 +60,29 @@ struct StackFrame {
         function_base(),
         source_file_name(),
         source_line(),
-        source_line_base() {}
+        source_line_base(),
+        trust(FRAME_TRUST_NONE) {}
   virtual ~StackFrame() {}
 
+  // Return a string describing how this stack frame was found
+  // by the stackwalker.
+  string trust_description() const {
+    switch (trust) {
+      case StackFrame::FRAME_TRUST_NONE:
+        return "unknown";
+      case StackFrame::FRAME_TRUST_CONTEXT:
+        return "given as instruction pointer in context";
+      case StackFrame::FRAME_TRUST_CFI:
+        return "call frame info";
+      case StackFrame::FRAME_TRUST_CFI_SCAN:
+        return "call frame info with scanning";
+      case StackFrame::FRAME_TRUST_FP:
+        return "previous frame's frame pointer";
+      case StackFrame::FRAME_TRUST_SCAN:
+        return "stack scanning";
+    }
+  };
+
   // The program counter location as an absolute virtual address.  For the
   // innermost called frame in a stack, this will be an exact program counter
   // or instruction pointer value.  For all other frames, this will be within
@@ -77,6 +110,10 @@ struct StackFrame {
   // The start address of the source line, may be omitted if debug symbols
   // are not available.
   u_int64_t source_line_base;
+
+  // Amount of trust the stack walker has in the instruction pointer
+  // of this frame.
+  FrameTrust trust;
 };
 
 }  // namespace google_breakpad

src/google_breakpad/processor/stack_frame_cpu.h

@@ -70,23 +70,9 @@ struct StackFrameX86 : public StackFrame {
     CONTEXT_VALID_ALL  = -1
   };
 
-  // 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),
        windows_frame_info(NULL),
        cfi_frame_info(NULL) {}
   ~StackFrameX86();
@@ -101,10 +87,6 @@ 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;
 
   // Any stack walking information we found describing this.instruction.
   // These may be NULL if there is no such information for that address.

src/google_breakpad/processor/stackwalker.h

@@ -44,12 +44,12 @@
 #include <set>
 #include <string>
 #include "google_breakpad/common/breakpad_types.h"
+#include "google_breakpad/processor/code_modules.h"
+#include "google_breakpad/processor/memory_region.h"
 
 namespace google_breakpad {
 
 class CallStack;
-class CodeModules;
-class MemoryRegion;
 class MinidumpContext;
 class SourceLineResolverInterface;
 struct StackFrame;
@@ -108,6 +108,39 @@ class Stackwalker {
   // Returns false otherwise.
   bool InstructionAddressSeemsValid(u_int64_t address);
 
+  // Scan the stack starting at location_start, looking for an address
+  // that looks like a valid instruction pointer. Addresses must
+  // 1) be contained in the current stack memory
+  // 2) pass the checks in InstructionAddressSeemsValid
+  //
+  // Returns true if a valid-looking instruction pointer was found.
+  // When returning true, sets location_found to the address at which
+  // the value was found, and ip_found to the value contained at that
+  // location in memory.
+  template<typename InstructionType>
+  bool ScanForReturnAddress(InstructionType location_start,
+                            InstructionType *location_found,
+                            InstructionType *ip_found) {
+    const int kRASearchWords = 15;
+    for (InstructionType location = location_start;
+         location <= location_start + kRASearchWords * sizeof(InstructionType);
+         location += sizeof(InstructionType)) {
+      InstructionType ip;
+      if (!memory_->GetMemoryAtAddress(location, &ip))
+        break;
+
+      if (modules_ && modules_->GetModuleForAddress(ip) &&
+          InstructionAddressSeemsValid(ip)) {
+
+        *ip_found = ip;
+        *location_found = location;
+        return true;
+      }
+    }
+    // nothing found
+    return false;
+  }
+
   // Information about the system that produced the minidump.  Subclasses
   // and the SymbolSupplier may find this information useful.
   const SystemInfo *system_info_;