Files
clang-p2996/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp
Fred Riss b40ee7ff1b [lldb/MemoryHistoryAsan] Fix address resolution for recorded backtraces
Summary:
The memory history plugin for Asan creates a HistoryThread with the
recorded PC values provided by the Asan runtime. In other cases,
thoses PCs are gathered by LLDB directly.

The PCs returned by the Asan runtime are the PCs of the calls in the
backtrace, not the return addresses you would normally get when
unwinding the stack (look for a call to GetPreviousIntructionPc in
AsanGetStack).

When the above addresses are passed to the unwinder, it will subtract
1 from each address of the non zero frames because it treats them as
return addresses. This can lead to the final report referencing the
wrong line.

This patch fixes this issue by threading a flag through HistoryThread
and HistoryUnwinder that tells them to treat every frame like the
first one. The Asan MemoryHistory plugin can then use this flag.

This fixes running TestMemoryHistory on arm64 devices, although it's
hard to guarantee that the test will continue to exhibit the boundary
condition that triggers this bug.

Reviewers: jasonmolenda, kubamracek

Subscribers: kristof.beyls, danielkiss, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D76341
2020-03-18 13:18:02 -07:00

74 lines
2.3 KiB
C++

//===-- HistoryUnwind.cpp -------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/lldb-private.h"
#include "Plugins/Process/Utility/HistoryUnwind.h"
#include "Plugins/Process/Utility/RegisterContextHistory.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include <memory>
using namespace lldb;
using namespace lldb_private;
// Constructor
HistoryUnwind::HistoryUnwind(Thread &thread, std::vector<lldb::addr_t> pcs,
bool pcs_are_call_addresses)
: Unwind(thread), m_pcs(pcs),
m_pcs_are_call_addresses(pcs_are_call_addresses) {}
// Destructor
HistoryUnwind::~HistoryUnwind() {}
void HistoryUnwind::DoClear() {
std::lock_guard<std::recursive_mutex> guard(m_unwind_mutex);
m_pcs.clear();
}
lldb::RegisterContextSP
HistoryUnwind::DoCreateRegisterContextForFrame(StackFrame *frame) {
RegisterContextSP rctx;
if (frame) {
addr_t pc = frame->GetFrameCodeAddress().GetLoadAddress(
&frame->GetThread()->GetProcess()->GetTarget());
if (pc != LLDB_INVALID_ADDRESS) {
rctx = std::make_shared<RegisterContextHistory>(
*frame->GetThread().get(), frame->GetConcreteFrameIndex(),
frame->GetThread()->GetProcess()->GetAddressByteSize(), pc);
}
}
return rctx;
}
bool HistoryUnwind::DoGetFrameInfoAtIndex(uint32_t frame_idx, lldb::addr_t &cfa,
lldb::addr_t &pc,
bool &behaves_like_zeroth_frame) {
// FIXME do not throw away the lock after we acquire it..
std::unique_lock<std::recursive_mutex> guard(m_unwind_mutex);
guard.unlock();
if (frame_idx < m_pcs.size()) {
cfa = frame_idx;
pc = m_pcs[frame_idx];
if (m_pcs_are_call_addresses)
behaves_like_zeroth_frame = true;
else
behaves_like_zeroth_frame = (frame_idx == 0);
return true;
}
return false;
}
uint32_t HistoryUnwind::DoGetFrameCount() { return m_pcs.size(); }