From bb95a5cf07ac245c3dadfa33254f34f80a9d2cd9 Mon Sep 17 00:00:00 2001
From: Keno Fischer <kfischer@college.harvard.edu>
Date: Tue, 27 Aug 2013 15:01:22 -0400
Subject: [PATCH] Add option to step with DWARF

---
 include/libunwind.h  |  2 ++
 src/UnwindCursor.hpp | 17 ++++++++++++-----
 src/libuwind.cxx     | 30 ++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/include/libunwind.h b/include/libunwind.h
index ea70420..9b6dc39 100644
--- a/include/libunwind.h
+++ b/include/libunwind.h
@@ -104,6 +104,8 @@ extern int         unw_get_proc_name(unw_cursor_t*, char*, size_t, unw_word_t*)
 //extern int       unw_get_save_loc(unw_cursor_t*, int, unw_save_loc_t*);
 #endif
 
+extern int        unw_init_local_dwarf(unw_cursor_t*, unw_context_t*);
+
 
 #if UNW_REMOTE
 /* 
diff --git a/src/UnwindCursor.hpp b/src/UnwindCursor.hpp
index ad89051..637ef7b 100644
--- a/src/UnwindCursor.hpp
+++ b/src/UnwindCursor.hpp
@@ -320,6 +320,7 @@ class UnwindCursor
 	virtual bool		isSignalFrame();
 	virtual bool		getFunctionName(char* buf, size_t bufLen, unw_word_t* offset);
 	virtual void		setInfoBasedOnIPRegister(bool isReturnAddress=false);
+	virtual void 		setForceDWARF(bool force);
 
 	void				operator delete(void* p, size_t size) {}
 
@@ -348,7 +349,7 @@ class UnwindCursor
 	bool				mustUseDwarf() const { return false; }
   #endif
 #else
-	bool				mustUseDwarf() const { R dummy; uint32_t offset; return dwarfWithOffset(dummy, offset); }
+	bool				mustUseDwarf() const { R dummy; uint32_t offset; return fForceDwarf || dwarfWithOffset(dummy, offset); }
 #endif
 
 	bool				dwarfWithOffset(uint32_t& offset) const { R dummy; return dwarfWithOffset(dummy, offset); }
@@ -391,17 +392,18 @@ class UnwindCursor
 	compact_unwind_encoding_t		dwarfEncoding(Registers_ppc&)	const { return 0; }
 
 	unw_proc_info_t				fInfo;
-	R							fRegisters;
-	A&							fAddressSpace;
 	bool						fUnwindInfoMissing;
 	bool						fIsSignalFrame;
+	bool 						fForceDwarf;
+	R							fRegisters;
+	A&							fAddressSpace;
 };
 
 typedef UnwindCursor<LocalAddressSpace,Registers_x86> AbstractUnwindCursor;
 
 template <typename A, typename R>
 UnwindCursor<A,R>::UnwindCursor(unw_context_t* context, A& as)
-  : fRegisters(context), fAddressSpace(as), fUnwindInfoMissing(false), fIsSignalFrame(false)
+  : fUnwindInfoMissing(false), fIsSignalFrame(false), fForceDwarf(false), fRegisters(context), fAddressSpace(as)
 {
 	COMPILE_TIME_ASSERT( sizeof(UnwindCursor<A,R>) < sizeof(unw_cursor_t) );
 
@@ -410,7 +412,7 @@ UnwindCursor<A,R>::UnwindCursor(unw_context_t* context, A& as)
 
 template <typename A, typename R>
 UnwindCursor<A,R>::UnwindCursor(A& as, thread_t thread)
-  : fAddressSpace(as), fUnwindInfoMissing(false), fIsSignalFrame(false)
+  : fUnwindInfoMissing(false), fIsSignalFrame(false), fForceDwarf(false), fAddressSpace(as)
 {
 	bzero(&fInfo, sizeof(fInfo));
 	// FIXME
@@ -471,6 +473,11 @@ bool UnwindCursor<A,R>::isSignalFrame()
 	 return fIsSignalFrame;
 }
 
+template <typename A, typename R>
+void UnwindCursor<A,R>::setForceDWARF(bool force) 
+{ 
+	fForceDwarf = force;
+}
 
 template <typename A, typename R>
 bool UnwindCursor<A,R>::getInfoFromDwarfSection(pint_t pc, pint_t mh, pint_t ehSectionStart, uint32_t sectionLength, uint32_t sectionOffsetOfFDE)
diff --git a/src/libuwind.cxx b/src/libuwind.cxx
index 8d59507..9a2d4c8 100644
--- a/src/libuwind.cxx
+++ b/src/libuwind.cxx
@@ -63,12 +63,42 @@ EXPORT int unw_init_local(unw_cursor_t* cursor, unw_context_t* context)
 	// use "placement new" to allocate UnwindCursor in the cursor buffer
 #if __i386__
 	new ((void*)cursor) UnwindCursor<LocalAddressSpace,Registers_x86>(context, sThisAddressSpace);
+	static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,Registers_x86>), "libunwind header outdated");
 #elif __x86_64__
 	new ((void*)cursor) UnwindCursor<LocalAddressSpace,Registers_x86_64>(context, sThisAddressSpace);
+	static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,Registers_x86_64>), "libunwind header outdated");
 #elif __ppc__
 	new ((void*)cursor) UnwindCursor<LocalAddressSpace,Registers_ppc>(context, sThisAddressSpace);
+	static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,Registers_ppc>), "libunwind header outdated");
 #endif
+
+	AbstractUnwindCursor* co = (AbstractUnwindCursor*)cursor;
+	co->setInfoBasedOnIPRegister();
+
+	return UNW_ESUCCESS;
+}
+
+
+///
+/// create a cursor of a thread in this process given 'context' recorded by unw_getcontext()
+///
+EXPORT int unw_init_local_dwarf(unw_cursor_t* cursor, unw_context_t* context)
+{
+	DEBUG_PRINT_API("unw_init_local(cursor=%p, context=%p)\n", cursor, context);
+	// use "placement new" to allocate UnwindCursor in the cursor buffer
+#if __i386__
+	new ((void*)cursor) UnwindCursor<LocalAddressSpace,Registers_x86>(context, sThisAddressSpace);
+	static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,Registers_x86>), "libunwind header outdated");
+#elif __x86_64__
+	new ((void*)cursor) UnwindCursor<LocalAddressSpace,Registers_x86_64>(context, sThisAddressSpace);
+	static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,Registers_x86_64>), "libunwind header outdated");
+#elif __ppc__
+	new ((void*)cursor) UnwindCursor<LocalAddressSpace,Registers_ppc>(context, sThisAddressSpace);
+	static_assert(sizeof(unw_cursor_t) >= sizeof(UnwindCursor<LocalAddressSpace,Registers_ppc>), "libunwind header outdated");
+#endif
+
 	AbstractUnwindCursor* co = (AbstractUnwindCursor*)cursor;
+	co->setForceDWARF(true);
 	co->setInfoBasedOnIPRegister();
 
 	return UNW_ESUCCESS;