[Lldb-commits] [lldb] r197761 - Partially revert a patch from Ashok Thirumurthi in r191430.
Jason Molenda
jmolenda at apple.com
Thu Dec 19 17:05:12 PST 2013
Author: jmolenda
Date: Thu Dec 19 19:05:11 2013
New Revision: 197761
URL: http://llvm.org/viewvc/llvm-project?rev=197761&view=rev
Log:
Partially revert a patch from Ashok Thirumurthi in r191430.
The original code was not completely correct, but a form of
this check is necessary to avoid an infinite recursion on
some unwind cases where a function unwinds to itself with the
same CFA. Ashok thought the recursion would be caught in
RegisterContextLLDB but this one isn't - we still need it here.
<rdar://problem/15664282>
Modified:
lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp
Modified: lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp?rev=197761&r1=197760&r2=197761&view=diff
==============================================================================
--- lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp (original)
+++ lldb/trunk/source/Plugins/Process/Utility/RegisterContextLLDB.cpp Thu Dec 19 19:05:11 2013
@@ -96,6 +96,7 @@ RegisterContextLLDB::InitializeZerothFra
if (reg_ctx_sp.get() == NULL)
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("frame does not have a register context");
return;
}
@@ -104,6 +105,7 @@ RegisterContextLLDB::InitializeZerothFra
if (current_pc == LLDB_INVALID_ADDRESS)
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("frame does not have a pc");
return;
}
@@ -198,6 +200,7 @@ RegisterContextLLDB::InitializeZerothFra
if (!active_row.get())
{
+ UnwindLogMsg ("could not find an unwindplan row for this frame's pc");
m_frame_type = eNotAValidFrame;
return;
}
@@ -206,6 +209,7 @@ RegisterContextLLDB::InitializeZerothFra
addr_t cfa_regval = LLDB_INVALID_ADDRESS;
if (!ReadGPRValue (row_register_kind, active_row->GetCFARegister(), cfa_regval))
{
+ UnwindLogMsg ("could not read CFA register for this frame.");
m_frame_type = eNotAValidFrame;
return;
}
@@ -230,17 +234,20 @@ RegisterContextLLDB::InitializeNonZeroth
if (IsFrameZero ())
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("non-zeroth frame tests positive for IsFrameZero -- that shouldn't happen.");
return;
}
if (!GetNextFrame().get() || !GetNextFrame()->IsValid())
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("Could not get next frame, marking this frame as invalid.");
return;
}
if (!m_thread.GetRegisterContext())
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("Could not get register context for this thread, marking this frame as invalid.");
return;
}
@@ -266,6 +273,7 @@ RegisterContextLLDB::InitializeNonZeroth
if (pc == 0)
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("this frame has a pc of 0x0");
return;
}
@@ -305,6 +313,7 @@ RegisterContextLLDB::InitializeNonZeroth
{
// anywhere other than the second frame, a non-executable pc means we're off in the weeds -- stop now.
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("pc is in a non-executable section of memory and this isn't the 2nd frame in the stack walk.");
return;
}
}
@@ -353,6 +362,7 @@ RegisterContextLLDB::InitializeNonZeroth
&& (permissions & ePermissionsReadable) == 0)
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("the CFA points to a region of memory that is not readable");
return;
}
}
@@ -367,10 +377,15 @@ RegisterContextLLDB::InitializeNonZeroth
return;
}
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("could not find any symbol for this pc, or a default unwind plan, to continue unwind.");
return;
}
bool resolve_tail_call_address = true; // m_current_pc can be one past the address range of the function...
+ // This will handle the case where the saved pc does not point to
+ // a function/symbol because it is beyond the bounds of the correct
+ // function and there's no symbol there. ResolveSymbolContextForAddress
+ // will fail to find a symbol, back up the pc by 1 and re-search.
uint32_t resolved_scope = pc_module_sp->ResolveSymbolContextForAddress (m_current_pc,
eSymbolContextFunction | eSymbolContextSymbol,
m_sym_ctx, resolve_tail_call_address);
@@ -501,6 +516,7 @@ RegisterContextLLDB::InitializeNonZeroth
if (!active_row.get())
{
m_frame_type = eNotAValidFrame;
+ UnwindLogMsg ("could not find unwind row for this pc");
return;
}
Modified: lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp?rev=197761&r1=197760&r2=197761&view=diff
==============================================================================
--- lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp (original)
+++ lldb/trunk/source/Plugins/Process/Utility/UnwindLLDB.cpp Thu Dec 19 19:05:11 2013
@@ -95,7 +95,13 @@ UnwindLLDB::AddFirstFrame ()
first_cursor_sp->reg_ctx_lldb_sp = reg_ctx_sp;
m_frames.push_back (first_cursor_sp);
return true;
+
unwind_done:
+ Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
+ if (log)
+ {
+ log->Printf ("th%d Unwind of this thread is complete.", m_thread.GetIndexID());
+ }
m_unwind_complete = true;
return false;
}
@@ -138,7 +144,12 @@ UnwindLLDB::AddOneMoreFrame (ABI *abi)
}
if (reg_ctx_sp.get() == NULL)
+ {
+ if (log)
+ log->Printf ("%*sFrame %d did not get a RegisterContext, stopping.",
+ cur_idx < 100 ? cur_idx : 100, "", cur_idx);
goto unwind_done;
+ }
if (!reg_ctx_sp->IsValid())
{
@@ -185,12 +196,26 @@ UnwindLLDB::AddOneMoreFrame (ABI *abi)
}
goto unwind_done;
}
+ if (!m_frames.empty())
+ {
+ // Infinite loop where the current cursor is the same as the previous one...
+ if (m_frames.back()->start_pc == cursor_sp->start_pc && m_frames.back()->cfa == cursor_sp->cfa)
+ {
+ if (log)
+ log->Printf ("th%d pc of this frame is the same as the previous frame and CFAs for both frames are identical -- stopping unwind", m_thread.GetIndexID());
+ goto unwind_done;
+ }
+ }
cursor_sp->reg_ctx_lldb_sp = reg_ctx_sp;
m_frames.push_back (cursor_sp);
return true;
unwind_done:
+ if (log)
+ {
+ log->Printf ("th%d Unwind of this thread is complete.", m_thread.GetIndexID());
+ }
m_unwind_complete = true;
return false;
}
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