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llvm-project/lldb/unittests/ObjectFile/ELF/TestObjectFileELF.cpp
Antonio Afonso ad6690afa3 Explicitly set entry point arch when it's thumb [Second Try] 
Summary:
This is a redo of D68069 because I reverted it due to some concerns that were now addressed along with the new comments that @labath added.

I found a case where the main android binary (app_process32) had thumb code at its entry point but no entry in the symbol table indicating this. This made lldb set a 4 byte breakpoint at that address (we default to arm code) instead of a 2 byte one (like we should for thumb).
The big deal with this is that the expression evaluator uses the entry point as a way to know when a JITed expression has finished executing by putting a breakpoint there. Because of this, evaluating expressions on certain android devices (Google Pixel something) made the process crash.
This was fixed by checking this specific situation when we parse the symbol table and add an artificial symbol for this 2 byte range and indicating that it's arm thumb.

I created 2 unit tests for this, one to check that now we know that the entry point is arm thumb, and the other to make sure we didn't change the behaviour for arm code.

I also run the following on the command line with the `app_process32` where I found the issue:
**Before:**
```
(lldb) dis -s 0x1640 -e 0x1644
app_process32[0x1640]: .long  0xf0004668                ; unknown opcode
```
**After:**
```
(lldb) dis -s 0x1640 -e 0x1644
app_process32`:
app_process32[0x1640] <+0>: mov    r0, sp
app_process32[0x1642]:      andeq  r0, r0, r0
```

Reviewers: clayborg, labath, wallace, espindola

Reviewed By: labath

Subscribers: labath, lldb-commits, MaskRay, kristof.beyls, arichardson, emaste, srhines

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D68533

llvm-svn: 374132
2019-10-08 23:44:49 +00:00

300 lines
10 KiB
C++
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//===-- TestObjectFileELF.cpp -----------------------------------*- C++ -*-===//
//
//
// 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 "Plugins/ObjectFile/ELF/ObjectFileELF.h"
#include "Plugins/SymbolFile/Symtab/SymbolFileSymtab.h"
#include "TestingSupport/TestUtilities.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/Section.h"
#include "lldb/Host/FileSystem.h"
#include "lldb/Host/HostInfo.h"
#include "lldb/Utility/DataBufferHeap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/Support/Compression.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Testing/Support/Error.h"
#include "gtest/gtest.h"
using namespace lldb_private;
using namespace lldb;
class ObjectFileELFTest : public testing::Test {
public:
void SetUp() override {
FileSystem::Initialize();
HostInfo::Initialize();
ObjectFileELF::Initialize();
SymbolFileSymtab::Initialize();
}
void TearDown() override {
SymbolFileSymtab::Terminate();
ObjectFileELF::Terminate();
HostInfo::Terminate();
FileSystem::Terminate();
}
protected:
};
TEST_F(ObjectFileELFTest, SectionsResolveConsistently) {
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_X86_64
Entry: 0x0000000000400180
Sections:
- Name: .note.gnu.build-id
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x0000000000400158
AddressAlign: 0x0000000000000004
Content: 040000001400000003000000474E55003F3EC29E3FD83E49D18C4D49CD8A730CC13117B6
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000400180
AddressAlign: 0x0000000000000010
Content: 554889E58B042500106000890425041060005DC3
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
Address: 0x0000000000601000
AddressAlign: 0x0000000000000004
Content: 2F000000
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
Address: 0x0000000000601004
AddressAlign: 0x0000000000000004
Size: 0x0000000000000004
Symbols:
- Name: Y
Type: STT_OBJECT
Section: .data
Value: 0x0000000000601000
Size: 0x0000000000000004
Binding: STB_GLOBAL
- Name: _start
Type: STT_FUNC
Section: .text
Value: 0x0000000000400180
Size: 0x0000000000000014
Binding: STB_GLOBAL
- Name: X
Type: STT_OBJECT
Section: .bss
Value: 0x0000000000601004
Size: 0x0000000000000004
Binding: STB_GLOBAL
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());
ModuleSpec spec{FileSpec(ExpectedFile->name())};
spec.GetSymbolFileSpec().SetFile(ExpectedFile->name(),
FileSpec::Style::native);
auto module_sp = std::make_shared<Module>(spec);
SectionList *list = module_sp->GetSectionList();
ASSERT_NE(nullptr, list);
auto bss_sp = list->FindSectionByName(ConstString(".bss"));
ASSERT_NE(nullptr, bss_sp);
auto data_sp = list->FindSectionByName(ConstString(".data"));
ASSERT_NE(nullptr, data_sp);
auto text_sp = list->FindSectionByName(ConstString(".text"));
ASSERT_NE(nullptr, text_sp);
const Symbol *X = module_sp->FindFirstSymbolWithNameAndType(ConstString("X"),
eSymbolTypeAny);
ASSERT_NE(nullptr, X);
EXPECT_EQ(bss_sp, X->GetAddress().GetSection());
const Symbol *Y = module_sp->FindFirstSymbolWithNameAndType(ConstString("Y"),
eSymbolTypeAny);
ASSERT_NE(nullptr, Y);
EXPECT_EQ(data_sp, Y->GetAddress().GetSection());
const Symbol *start = module_sp->FindFirstSymbolWithNameAndType(
ConstString("_start"), eSymbolTypeAny);
ASSERT_NE(nullptr, start);
EXPECT_EQ(text_sp, start->GetAddress().GetSection());
}
// Test that GetModuleSpecifications works on an "atypical" object file which
// has section headers right after the ELF header (instead of the more common
// layout where the section headers are at the very end of the object file).
//
// Test file generated with yaml2obj (@svn rev 324254) from the following input:
/*
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_X86_64
Entry: 0x00000000004003D0
Sections:
- Name: .note.gnu.build-id
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x0000000000400274
AddressAlign: 0x0000000000000004
Content: 040000001400000003000000474E55001B8A73AC238390E32A7FF4AC8EBE4D6A41ECF5C9
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x00000000004003D0
AddressAlign: 0x0000000000000010
Content: DEADBEEFBAADF00D
...
*/
TEST_F(ObjectFileELFTest, GetModuleSpecifications_EarlySectionHeaders) {
std::string SO = GetInputFilePath("early-section-headers.so");
ModuleSpecList Specs;
ASSERT_EQ(1u, ObjectFile::GetModuleSpecifications(FileSpec(SO), 0, 0, Specs));
ModuleSpec Spec;
ASSERT_TRUE(Specs.GetModuleSpecAtIndex(0, Spec)) ;
UUID Uuid;
Uuid.SetFromStringRef("1b8a73ac238390e32a7ff4ac8ebe4d6a41ecf5c9", 20);
EXPECT_EQ(Spec.GetUUID(), Uuid);
}
TEST_F(ObjectFileELFTest, GetSymtab_NoSymEntryPointArmThumbAddressClass) {
/*
// nosym-entrypoint-arm-thumb.s
.thumb_func
_start:
mov r0, #42
mov r7, #1
svc #0
// arm-linux-androideabi-as nosym-entrypoint-arm-thumb.s
// -o nosym-entrypoint-arm-thumb.o
// arm-linux-androideabi-ld nosym-entrypoint-arm-thumb.o
// -o nosym-entrypoint-arm-thumb -e 0x8075 -s
*/
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_ARM
Flags: [ EF_ARM_SOFT_FLOAT, EF_ARM_EABI_VER5 ]
Entry: 0x0000000000008075
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000008074
AddressAlign: 0x0000000000000002
Content: 2A20012700DF
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
Address: 0x0000000000009000
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
Address: 0x0000000000009000
AddressAlign: 0x0000000000000001
- Name: .note.gnu.gold-version
Type: SHT_NOTE
AddressAlign: 0x0000000000000004
Content: 040000000900000004000000474E5500676F6C6420312E3131000000
- Name: .ARM.attributes
Type: SHT_ARM_ATTRIBUTES
AddressAlign: 0x0000000000000001
Content: '4113000000616561626900010900000006020901'
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());
ModuleSpec spec{FileSpec(ExpectedFile->name())};
spec.GetSymbolFileSpec().SetFile(ExpectedFile->name(),
FileSpec::Style::native);
auto module_sp = std::make_shared<Module>(spec);
auto entry_point_addr = module_sp->GetObjectFile()->GetEntryPointAddress();
ASSERT_TRUE(entry_point_addr.GetOffset() & 1);
// Decrease the offsite by 1 to make it into a breakable address since this
// is Thumb.
entry_point_addr.SetOffset(entry_point_addr.GetOffset() - 1);
ASSERT_EQ(entry_point_addr.GetAddressClass(),
AddressClass::eCodeAlternateISA);
}
TEST_F(ObjectFileELFTest, GetSymtab_NoSymEntryPointArmAddressClass) {
/*
// nosym-entrypoint-arm.s
_start:
movs r0, #42
movs r7, #1
svc #0
// arm-linux-androideabi-as nosym-entrypoint-arm.s
// -o nosym-entrypoint-arm.o
// arm-linux-androideabi-ld nosym-entrypoint-arm.o
// -o nosym-entrypoint-arm -e 0x8074 -s
*/
auto ExpectedFile = TestFile::fromYaml(R"(
--- !ELF
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_ARM
Flags: [ EF_ARM_SOFT_FLOAT, EF_ARM_EABI_VER5 ]
Entry: 0x0000000000008074
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x0000000000008074
AddressAlign: 0x0000000000000004
Content: 2A00A0E30170A0E3000000EF
- Name: .data
Type: SHT_PROGBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
Address: 0x0000000000009000
AddressAlign: 0x0000000000000001
Content: ''
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_WRITE, SHF_ALLOC ]
Address: 0x0000000000009000
AddressAlign: 0x0000000000000001
- Name: .note.gnu.gold-version
Type: SHT_NOTE
AddressAlign: 0x0000000000000004
Content: 040000000900000004000000474E5500676F6C6420312E3131000000
- Name: .ARM.attributes
Type: SHT_ARM_ATTRIBUTES
AddressAlign: 0x0000000000000001
Content: '4113000000616561626900010900000006010801'
...
)");
ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded());
ModuleSpec spec{FileSpec(ExpectedFile->name())};
spec.GetSymbolFileSpec().SetFile(ExpectedFile->name(),
FileSpec::Style::native);
auto module_sp = std::make_shared<Module>(spec);
auto entry_point_addr = module_sp->GetObjectFile()->GetEntryPointAddress();
ASSERT_EQ(entry_point_addr.GetAddressClass(), AddressClass::eCode);
}
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