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A change in how we search for saved register values unintentionally 

allowed volatile registers to be returned up the stack.  That leads
to unexpected/incorrect values provided to the user and we need to
avoid that.
<rdar://problem/12714247>

llvm-svn: 168123
This commit is contained in:
Jason Molenda 2012-11-16 01:03:31 +00:00
parent 234ba6f2cd
commit aff2a269e3
4 changed files with 35 additions and 22 deletions
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38
lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
View File

@ -903,7 +903,7 @@ RegisterContextLLDB::IsSkipFrame () const
// Answer the question: Where did THIS frame save the CALLER frame ("previous" frame)'s register value?
bool
enum UnwindLLDB::RegisterSearchResult
RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_private::UnwindLLDB::RegisterLocation &regloc)
{
// Have we already found this register location?
@ -914,7 +914,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
if (iterator != m_registers.end())
{
regloc = iterator->second;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
}
@ -937,7 +937,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
regloc.type = UnwindLLDB::RegisterLocation::eRegisterValueInferred;
regloc.location.inferred_value = m_cfa;
m_registers[lldb_regnum] = regloc;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
// Look through the available UnwindPlans for the register location.
@ -955,7 +955,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
{
UnwindLogMsg ("could not convert lldb regnum %d into %d RegisterKind reg numbering scheme",
lldb_regnum, (int) unwindplan_registerkind);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
if (active_row->GetRegisterInfo (row_regnum, unwindplan_regloc))
{
@ -993,7 +993,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
else
UnwindLogMsg ("could not convert lldb regnum %d into %d RegisterKind reg numbering scheme",
lldb_regnum, (int) unwindplan_registerkind);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
}
@ -1064,7 +1064,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
if (reg_info && abi->RegisterIsVolatile (reg_info))
{
UnwindLogMsg ("did not supply reg location for %d because it is volatile", lldb_regnum);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterIsVolatile;
}
}
@ -1076,11 +1076,11 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
new_regloc.location.register_number = lldb_regnum;
m_registers[lldb_regnum] = new_regloc;
regloc = new_regloc;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
else
UnwindLogMsg ("could not supply caller's reg %d location", lldb_regnum);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
// unwindplan_regloc has valid contents about where to retrieve the register
@ -1090,7 +1090,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterNotSaved;
m_registers[lldb_regnum] = new_regloc;
UnwindLogMsg ("could not supply caller's reg %d location", lldb_regnum);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
if (unwindplan_regloc.IsSame())
@ -1098,11 +1098,11 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
if (IsFrameZero ())
{
UnwindLogMsg ("could not supply caller's reg %d location", lldb_regnum);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
else
{
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
}
@ -1112,7 +1112,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
regloc.type = UnwindLLDB::RegisterLocation::eRegisterValueInferred;
regloc.location.inferred_value = m_cfa + offset;
m_registers[lldb_regnum] = regloc;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
if (unwindplan_regloc.IsAtCFAPlusOffset())
@ -1121,7 +1121,7 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
regloc.type = UnwindLLDB::RegisterLocation::eRegisterSavedAtMemoryLocation;
regloc.location.target_memory_location = m_cfa + offset;
m_registers[lldb_regnum] = regloc;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
if (unwindplan_regloc.IsInOtherRegister())
@ -1131,12 +1131,12 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
if (!m_thread.GetRegisterContext()->ConvertBetweenRegisterKinds (unwindplan_registerkind, unwindplan_regnum, eRegisterKindLLDB, row_regnum_in_lldb))
{
UnwindLogMsg ("could not supply caller's reg %d location", lldb_regnum);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
regloc.type = UnwindLLDB::RegisterLocation::eRegisterInRegister;
regloc.location.register_number = row_regnum_in_lldb;
m_registers[lldb_regnum] = regloc;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
if (unwindplan_regloc.IsDWARFExpression() || unwindplan_regloc.IsAtDWARFExpression())
@ -1157,25 +1157,25 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
regloc.type = UnwindLLDB::RegisterLocation::eRegisterValueInferred;
regloc.location.inferred_value = val;
m_registers[lldb_regnum] = regloc;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
else
{
regloc.type = UnwindLLDB::RegisterLocation::eRegisterSavedAtMemoryLocation;
regloc.location.target_memory_location = val;
m_registers[lldb_regnum] = regloc;
return true;
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
}
UnwindLogMsg ("tried to use IsDWARFExpression or IsAtDWARFExpression for reg %d but failed", lldb_regnum);
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
UnwindLogMsg ("could not supply caller's reg %d location", lldb_regnum);
// FIXME UnwindPlan::Row types atDWARFExpression and isDWARFExpression are unsupported.
return false;
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
// If the Full unwindplan has been determined to be incorrect, this method will

2
lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
View File

@ -131,7 +131,7 @@ private:
// If a non-volatile register (a "preserved" register) is requested mid-stack and no frames "below" the requested
// stack have saved the register anywhere, it is safe to assume that frame 0's register values are still the same
// as the requesting frame's.
bool
lldb_private::UnwindLLDB::RegisterSearchResult
SavedLocationForRegister (uint32_t lldb_regnum, lldb_private::UnwindLLDB::RegisterLocation &regloc);
bool

10
lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
View File

@ -272,15 +272,21 @@ UnwindLLDB::SearchForSavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
// isn't saved by frame_num, none of the frames lower on the stack will have a useful value.
if (pc_or_return_address_reg)
{
if (m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc))
UnwindLLDB::RegisterSearchResult result;
result = m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc);
if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound)
return true;
else
return false;
}
while (frame_num >= 0)
{
if (m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc))
UnwindLLDB::RegisterSearchResult result;
result = m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc);
if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound)
return true;
if (result == UnwindLLDB::RegisterSearchResult::eRegisterIsVolatile)
return false;
frame_num--;
}
return false;

7
lldb/source/Plugins/Process/Utility/UnwindLLDB.h
View File

@ -30,6 +30,13 @@ public:
virtual
~UnwindLLDB() { }
enum RegisterSearchResult
{
eRegisterFound = 0,
eRegisterNotFound,
eRegisterIsVolatile
};
protected:
friend class lldb_private::RegisterContextLLDB;