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Fix backtrace of noreturn functions situated at the end of a module 

Summary:
When a call instruction is the last instruction in a function, the
backtrace PC will point past the end of the function. We already had
special code to handle that, but we did not handle the case where the PC
ends up outside of the bounds of the module containing the function,
which is a situation that occured in TestNoreturnUnwind on android for
some arch/compiler combinations.

I fix this by adding an argument to Address resolution code which states
that we are ok with addresses pointing to the end of a module/section to
resolve to that module/section.

I create a reproducible test case for this situation by hand-crafting an
executable which has a noreturn function at the end of a module.

Reviewers: jasonmolenda, jingham

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D32022

llvm-svn: 304976
This commit is contained in:
Pavel Labath 2017-06-08 13:26:35 +00:00
parent 62fb8498d3
commit c3c721222d
14 changed files with 135 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lldb/include/lldb/Core/Address.h
View File

@ -422,6 +422,10 @@ public:
/// a section + offset. The Target's SectionLoadList object
/// is used to resolve the address.
///
/// @param[in] allow_section_end
/// If true, treat an address pointing to the end of the module as
/// belonging to that module.
///
/// @return
/// Returns \b true if the load address was resolved to be
/// section/offset, \b false otherwise. It is often ok for an
@ -429,11 +433,13 @@ public:
/// happens for JIT'ed code, or any load addresses on the stack
/// or heap.
//------------------------------------------------------------------
bool SetLoadAddress(lldb::addr_t load_addr, Target *target);
bool SetLoadAddress(lldb::addr_t load_addr, Target *target,
bool allow_section_end = false);
bool SetOpcodeLoadAddress(
lldb::addr_t load_addr, Target *target,
lldb::AddressClass addr_class = lldb::eAddressClassInvalid);
lldb::AddressClass addr_class = lldb::eAddressClassInvalid,
bool allow_section_end = false);
bool SetCallableLoadAddress(lldb::addr_t load_addr, Target *target);

3
lldb/include/lldb/Core/Section.h
View File

@ -143,7 +143,8 @@ public:
lldb::addr_t GetLoadBaseAddress(Target *target) const;
bool ResolveContainedAddress(lldb::addr_t offset, Address &so_addr) const;
bool ResolveContainedAddress(lldb::addr_t offset, Address &so_addr,
bool allow_section_end = false) const;
lldb::offset_t GetFileOffset() const { return m_file_offset; }

3
lldb/include/lldb/Target/SectionLoadList.h
View File

@ -47,7 +47,8 @@ public:
lldb::addr_t GetSectionLoadAddress(const lldb::SectionSP &section_sp) const;
bool ResolveLoadAddress(lldb::addr_t load_addr, Address &so_addr) const;
bool ResolveLoadAddress(lldb::addr_t load_addr, Address &so_addr,
bool allow_section_end = false) const;
bool SetSectionLoadAddress(const lldb::SectionSP &section_sp,
lldb::addr_t load_addr,

2
lldb/packages/Python/lldbsuite/test/functionalities/unwind/noreturn/TestNoreturnUnwind.py
View File

@ -17,8 +17,6 @@ class NoreturnUnwind(TestBase):
mydir = TestBase.compute_mydir(__file__)
@skipIfWindows # clang-cl does not support gcc style attributes.
@expectedFailureAndroid(bugnumber="llvm.org/pr31192")
@expectedFailureAll(bugnumber="llvm.org/pr31192", oslist=['linux'], compiler="gcc", archs=['arm'])
def test(self):
"""Test that we can backtrace correctly with 'noreturn' functions on the stack"""
self.build()

2
lldb/packages/Python/lldbsuite/test/functionalities/unwind/noreturn/main.c
View File

@ -29,8 +29,6 @@ func_a (void)
int
main (int argc, char *argv[])
{
sleep (2);
func_a ();
return 0;

53
lldb/packages/Python/lldbsuite/test/functionalities/unwind/noreturn/module-end/TestNoReturnModuleEnd.py Normal file
View File

@ -0,0 +1,53 @@
"""
Test that we properly display the backtrace when a noreturn function happens to
be at the end of the stack.
"""
from __future__ import print_function
import shutil
import struct
import lldb
from lldbsuite.test.decorators import *
from lldbsuite.test.lldbtest import *
from lldbsuite.test import lldbutil
class TestNoreturnModuleEnd(TestBase):
NO_DEBUG_INFO_TESTCASE = True
mydir = TestBase.compute_mydir(__file__)
def setUp(self):
super(TestNoreturnModuleEnd, self).setUp()
self._initial_platform = lldb.DBG.GetSelectedPlatform()
def tearDown(self):
lldb.DBG.SetSelectedPlatform(self._initial_platform)
super(TestNoreturnModuleEnd, self).tearDown()
def test(self):
target = self.dbg.CreateTarget("test.out")
process = target.LoadCore("test.core")
self.assertTrue(process.IsValid(), PROCESS_IS_VALID)
self.assertEqual(process.GetNumThreads(), 1)
thread = process.GetSelectedThread()
self.assertTrue(thread.IsValid())
backtrace = [
["func2", 3],
["func1", 8],
["_start", 8],
]
self.assertEqual(thread.GetNumFrames(), len(backtrace))
for i in range(len(backtrace)):
frame = thread.GetFrameAtIndex(i)
self.assertTrue(frame.IsValid())
symbol = frame.GetSymbol()
self.assertTrue(symbol.IsValid())
self.assertEqual(symbol.GetName(), backtrace[i][0])
function_start = symbol.GetStartAddress().GetLoadAddress(target)
self.assertEquals(function_start + backtrace[i][1], frame.GetPC())
self.dbg.DeleteTarget(target)

35
lldb/packages/Python/lldbsuite/test/functionalities/unwind/noreturn/module-end/a.s Normal file
View File

@ -0,0 +1,35 @@
# compile this with:
# as a.s -o a.o --32 && ld a.o -m elf_i386
# generate core file with:
# ulimit -s 12 && ./a.out
.text
.globl func2
.type func2, @function
func2:
pushl %ebp
movl %esp, %ebp
movl 0, %eax
popl %ebp
ret
.size func2, .-func2
.globl _start
.type _start, @function
_start:
pushl %ebp
movl %esp, %ebp
call func1
popl %ebp
ret
.size _start, .-_start
.globl func1
.type func1, @function
func1:
pushl %ebp
movl %esp, %ebp
call func2
.size func1, .-func1

BIN
lldb/packages/Python/lldbsuite/test/functionalities/unwind/noreturn/module-end/test.core Normal file
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BIN
lldb/packages/Python/lldbsuite/test/functionalities/unwind/noreturn/module-end/test.out Executable file
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12
lldb/source/Core/Address.cpp
View File

@ -361,8 +361,9 @@ addr_t Address::GetOpcodeLoadAddress(Target *target,
}
bool Address::SetOpcodeLoadAddress(lldb::addr_t load_addr, Target *target,
AddressClass addr_class) {
if (SetLoadAddress(load_addr, target)) {
AddressClass addr_class,
bool allow_section_end) {
if (SetLoadAddress(load_addr, target, allow_section_end)) {
if (target) {
if (addr_class == eAddressClassInvalid)
addr_class = GetAddressClass();
@ -1001,9 +1002,10 @@ AddressClass Address::GetAddressClass() const {
return eAddressClassUnknown;
}
bool Address::SetLoadAddress(lldb::addr_t load_addr, Target *target) {
if (target &&
target->GetSectionLoadList().ResolveLoadAddress(load_addr, *this))
bool Address::SetLoadAddress(lldb::addr_t load_addr, Target *target,
bool allow_section_end) {
if (target && target->GetSectionLoadList().ResolveLoadAddress(
load_addr, *this, allow_section_end))
return true;
m_section_wp.reset();
m_offset = load_addr;

10
lldb/source/Core/Section.cpp
View File

@ -220,18 +220,18 @@ addr_t Section::GetLoadBaseAddress(Target *target) const {
return load_base_addr;
}
bool Section::ResolveContainedAddress(addr_t offset, Address &so_addr) const {
bool Section::ResolveContainedAddress(addr_t offset, Address &so_addr,
bool allow_section_end) const {
const size_t num_children = m_children.GetSize();
if (num_children > 0) {
for (size_t i = 0; i < num_children; i++) {
Section *child_section = m_children.GetSectionAtIndex(i).get();
addr_t child_offset = child_section->GetOffset();
if (child_offset <= offset &&
offset - child_offset < child_section->GetByteSize())
offset - child_offset <
child_section->GetByteSize() + (allow_section_end ? 1 : 0))
return child_section->ResolveContainedAddress(offset - child_offset,
so_addr);
}
so_addr, allow_section_end);
}
so_addr.SetOffset(offset);
so_addr.SetSection(const_cast<Section *>(this)->shared_from_this());

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

@ -329,7 +329,8 @@ void RegisterContextLLDB::InitializeNonZerothFrame() {
if (abi)
pc = abi->FixCodeAddress(pc);
m_current_pc.SetLoadAddress(pc, &process->GetTarget());
const bool allow_section_end = true;
m_current_pc.SetLoadAddress(pc, &process->GetTarget(), allow_section_end);
// If we don't have a Module for some reason, we're not going to find
// symbol/function information - just
@ -477,11 +478,12 @@ void RegisterContextLLDB::InitializeNonZerothFrame() {
// Or if we're in the middle of the stack (and not "above" an asynchronous
// event like sigtramp),
// and our "current" pc is the start of a function...
if (m_sym_ctx_valid && GetNextFrame()->m_frame_type != eTrapHandlerFrame &&
if (GetNextFrame()->m_frame_type != eTrapHandlerFrame &&
GetNextFrame()->m_frame_type != eDebuggerFrame &&
addr_range.GetBaseAddress().IsValid() &&
(!m_sym_ctx_valid ||
(addr_range.GetBaseAddress().IsValid() &&
addr_range.GetBaseAddress().GetSection() == m_current_pc.GetSection() &&
addr_range.GetBaseAddress().GetOffset() == m_current_pc.GetOffset()) {
addr_range.GetBaseAddress().GetOffset() == m_current_pc.GetOffset()))) {
decr_pc_and_recompute_addr_range = true;
}

15
lldb/source/Target/SectionLoadList.cpp
View File

@ -207,8 +207,8 @@ bool SectionLoadList::SetSectionUnloaded(const lldb::SectionSP &section_sp,
return erased;
}
bool SectionLoadList::ResolveLoadAddress(addr_t load_addr,
Address &so_addr) const {
bool SectionLoadList::ResolveLoadAddress(addr_t load_addr, Address &so_addr,
bool allow_section_end) const {
// First find the top level section that this load address exists in
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (!m_addr_to_sect.empty()) {
@ -220,10 +220,11 @@ bool SectionLoadList::ResolveLoadAddress(addr_t load_addr,
const addr_t pos_load_addr = pos->first;
if (load_addr >= pos_load_addr) {
addr_t offset = load_addr - pos_load_addr;
if (offset < pos->second->GetByteSize()) {
if (offset < pos->second->GetByteSize() + (allow_section_end ? 1 : 0)) {
// We have found the top level section, now we need to find the
// deepest child section.
return pos->second->ResolveContainedAddress(offset, so_addr);
return pos->second->ResolveContainedAddress(offset, so_addr,
allow_section_end);
}
}
} else {
@ -233,10 +234,12 @@ bool SectionLoadList::ResolveLoadAddress(addr_t load_addr,
m_addr_to_sect.rbegin();
if (load_addr >= rpos->first) {
addr_t offset = load_addr - rpos->first;
if (offset < rpos->second->GetByteSize()) {
if (offset <
rpos->second->GetByteSize() + (allow_section_end ? 1 : 0)) {
// We have found the top level section, now we need to find the
// deepest child section.
return rpos->second->ResolveContainedAddress(offset, so_addr);
return rpos->second->ResolveContainedAddress(offset, so_addr,
allow_section_end);
}
}
}

3
lldb/source/Target/StackFrame.cpp
View File

@ -191,9 +191,10 @@ const Address &StackFrame::GetFrameCodeAddress() {
if (thread_sp) {
TargetSP target_sp(thread_sp->CalculateTarget());
if (target_sp) {
const bool allow_section_end = true;
if (m_frame_code_addr.SetOpcodeLoadAddress(
m_frame_code_addr.GetOffset(), target_sp.get(),
eAddressClassCode)) {
eAddressClassCode, allow_section_end)) {
ModuleSP module_sp(m_frame_code_addr.GetModule());
if (module_sp) {
m_sc.module_sp = module_sp;