// -*- mode: C++ -*-

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// stackwalker_arm.h: arm-specific stackwalker.
//
// Provides stack frames given arm register context and a memory region
// corresponding to an arm stack.
//
// Author: Mark Mentovai, Ted Mielczarek


#ifndef PROCESSOR_STACKWALKER_ARM_H__
#define PROCESSOR_STACKWALKER_ARM_H__

#include "breakpad/common/breakpad_types.h"
#include "breakpad/common/minidump_format.h"
#include "google_breakpad/processor/stackwalker.h"

namespace google_breakpad {

class CodeModules;

class StackwalkerARM : public Stackwalker {
 public:
  // context is an arm context object that gives access to arm-specific
  // register state corresponding to the innermost called frame to be
  // included in the stack.  The other arguments are passed directly through
  // to the base Stackwalker constructor.
  StackwalkerARM(const SystemInfo* system_info,
                 const MDRawContextARM* context,
                 int fp_register,
                 MemoryRegion* memory,
                 const CodeModules* modules,
                 StackFrameSymbolizer* frame_symbolizer);

  // Change the context validity mask of the frame returned by
  // GetContextFrame to VALID. This is only for use by unit tests; the
  // default behavior is correct for all application code.
  void SetContextFrameValidity(int valid) { context_frame_validity_ = valid; }

 private:
  // Implementation of Stackwalker, using arm context and stack conventions.
  virtual StackFrame* GetContextFrame();
  virtual StackFrame* GetCallerFrame(const CallStack* stack,
                                     bool stack_scan_allowed);

  // Use cfi_frame_info (derived from STACK CFI records) to construct
  // the frame that called frames.back(). The caller takes ownership
  // of the returned frame. Return NULL on failure.
  StackFrameARM* GetCallerByCFIFrameInfo(const vector<StackFrame*> &frames,
                                         CFIFrameInfo* cfi_frame_info);

  // Use the frame pointer. The caller takes ownership of the returned frame.
  // Return NULL on failure.
  StackFrameARM* GetCallerByFramePointer(const vector<StackFrame*> &frames);

  // Scan the stack for plausible return addresses. The caller takes ownership
  // of the returned frame. Return NULL on failure.
  StackFrameARM* GetCallerByStackScan(const vector<StackFrame*> &frames);

  // Stores the CPU context corresponding to the youngest stack frame, to
  // be returned by GetContextFrame.
  const MDRawContextARM* context_;

  // The register to use a as frame pointer. The value is -1 if frame pointer
  // cannot be used.
  int fp_register_;

  // Validity mask for youngest stack frame. This is always
  // CONTEXT_VALID_ALL in real use; it is only changeable for the sake of
  // unit tests.
  int context_frame_validity_;
};


}  // namespace google_breakpad


#endif  // PROCESSOR_STACKWALKER_ARM_H__
