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android_system_core/libunwindstack/tests/ElfTest.cpp
Christopher Ferris b9de87f7ed Add a new unwind method on error. 
If a function crashes by jumping into unexecutable code, the old method
could not unwind through that. Add a fallback method to set the pc from
the default return address location.

In addition, add a new finished check for steps. This will provide a method
to indicate that this step is the last step. This prevents cases where
the fallback method might be triggered incorrectly.

Update the libbacktrace code to unwind using the new methodology.

Update the unwind tool to use the new unwind methodology.

Add a new option to crasher that calls through a null function.

Create a new object, Unwinder, that encapsulates the a basic unwind. For now,
libbacktrace will still use the custom code.

Added new unit tests to cover the new cases. Also add a test that
crashes calling a nullptr as a function, and then has call frames in
the signal stack.

Bug: 65842173

Test: Pass all unit tests, verify crasher dumps properly.
Change-Id: Ia18430ab107e9f7bdf0e14a9b74710b1280bd7f4
2017-09-22 16:55:12 -07:00

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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <elf.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <gtest/gtest.h>
#include <unwindstack/Elf.h>
#include <unwindstack/MapInfo.h>
#include "ElfTestUtils.h"
#include "LogFake.h"
#include "MemoryFake.h"
#if !defined(PT_ARM_EXIDX)
#define PT_ARM_EXIDX 0x70000001
#endif
namespace unwindstack {
class ElfTest : public ::testing::Test {
protected:
void SetUp() override {
memory_ = new MemoryFake;
}
void InitElf32(uint32_t machine_type) {
Elf32_Ehdr ehdr;
TestInitEhdr<Elf32_Ehdr>(&ehdr, ELFCLASS32, machine_type);
ehdr.e_phoff = 0x100;
ehdr.e_ehsize = sizeof(ehdr);
ehdr.e_phentsize = sizeof(Elf32_Phdr);
ehdr.e_phnum = 1;
ehdr.e_shentsize = sizeof(Elf32_Shdr);
if (machine_type == EM_ARM) {
ehdr.e_flags = 0x5000200;
ehdr.e_phnum = 2;
}
memory_->SetMemory(0, &ehdr, sizeof(ehdr));
Elf32_Phdr phdr;
memset(&phdr, 0, sizeof(phdr));
phdr.p_type = PT_LOAD;
phdr.p_filesz = 0x10000;
phdr.p_memsz = 0x10000;
phdr.p_flags = PF_R | PF_X;
phdr.p_align = 0x1000;
memory_->SetMemory(0x100, &phdr, sizeof(phdr));
if (machine_type == EM_ARM) {
memset(&phdr, 0, sizeof(phdr));
phdr.p_type = PT_ARM_EXIDX;
phdr.p_offset = 0x30000;
phdr.p_vaddr = 0x30000;
phdr.p_paddr = 0x30000;
phdr.p_filesz = 16;
phdr.p_memsz = 16;
phdr.p_flags = PF_R;
phdr.p_align = 0x4;
memory_->SetMemory(0x100 + sizeof(phdr), &phdr, sizeof(phdr));
}
}
void InitElf64(uint32_t machine_type) {
Elf64_Ehdr ehdr;
TestInitEhdr<Elf64_Ehdr>(&ehdr, ELFCLASS64, machine_type);
ehdr.e_phoff = 0x100;
ehdr.e_flags = 0x5000200;
ehdr.e_ehsize = sizeof(ehdr);
ehdr.e_phentsize = sizeof(Elf64_Phdr);
ehdr.e_phnum = 1;
ehdr.e_shentsize = sizeof(Elf64_Shdr);
memory_->SetMemory(0, &ehdr, sizeof(ehdr));
Elf64_Phdr phdr;
memset(&phdr, 0, sizeof(phdr));
phdr.p_type = PT_LOAD;
phdr.p_filesz = 0x10000;
phdr.p_memsz = 0x10000;
phdr.p_flags = PF_R | PF_X;
phdr.p_align = 0x1000;
memory_->SetMemory(0x100, &phdr, sizeof(phdr));
}
MemoryFake* memory_;
};
TEST_F(ElfTest, invalid_memory) {
Elf elf(memory_);
ASSERT_FALSE(elf.Init());
ASSERT_FALSE(elf.valid());
}
TEST_F(ElfTest, elf_invalid) {
Elf elf(memory_);
InitElf32(EM_386);
// Corrupt the ELF signature.
memory_->SetData32(0, 0x7f000000);
ASSERT_FALSE(elf.Init());
ASSERT_FALSE(elf.valid());
ASSERT_TRUE(elf.interface() == nullptr);
std::string name;
ASSERT_FALSE(elf.GetSoname(&name));
uint64_t func_offset;
ASSERT_FALSE(elf.GetFunctionName(0, &name, &func_offset));
bool finished;
ASSERT_FALSE(elf.Step(0, nullptr, nullptr, &finished));
}
TEST_F(ElfTest, elf32_invalid_machine) {
Elf elf(memory_);
InitElf32(EM_PPC);
ResetLogs();
ASSERT_FALSE(elf.Init());
ASSERT_EQ("", GetFakeLogBuf());
ASSERT_EQ("4 unwind 32 bit elf that is neither arm nor x86: e_machine = 20\n\n",
GetFakeLogPrint());
}
TEST_F(ElfTest, elf64_invalid_machine) {
Elf elf(memory_);
InitElf64(EM_PPC64);
ResetLogs();
ASSERT_FALSE(elf.Init());
ASSERT_EQ("", GetFakeLogBuf());
ASSERT_EQ("4 unwind 64 bit elf that is neither aarch64 nor x86_64: e_machine = 21\n\n",
GetFakeLogPrint());
}
TEST_F(ElfTest, elf_arm) {
Elf elf(memory_);
InitElf32(EM_ARM);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.valid());
ASSERT_EQ(static_cast<uint32_t>(EM_ARM), elf.machine_type());
ASSERT_EQ(ELFCLASS32, elf.class_type());
ASSERT_TRUE(elf.interface() != nullptr);
}
TEST_F(ElfTest, elf_x86) {
Elf elf(memory_);
InitElf32(EM_386);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.valid());
ASSERT_EQ(static_cast<uint32_t>(EM_386), elf.machine_type());
ASSERT_EQ(ELFCLASS32, elf.class_type());
ASSERT_TRUE(elf.interface() != nullptr);
}
TEST_F(ElfTest, elf_arm64) {
Elf elf(memory_);
InitElf64(EM_AARCH64);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.valid());
ASSERT_EQ(static_cast<uint32_t>(EM_AARCH64), elf.machine_type());
ASSERT_EQ(ELFCLASS64, elf.class_type());
ASSERT_TRUE(elf.interface() != nullptr);
}
TEST_F(ElfTest, elf_x86_64) {
Elf elf(memory_);
InitElf64(EM_X86_64);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.valid());
ASSERT_EQ(static_cast<uint32_t>(EM_X86_64), elf.machine_type());
ASSERT_EQ(ELFCLASS64, elf.class_type());
ASSERT_TRUE(elf.interface() != nullptr);
}
TEST_F(ElfTest, gnu_debugdata_init_fail32) {
TestInitGnuDebugdata<Elf32_Ehdr, Elf32_Shdr>(ELFCLASS32, EM_ARM, false,
[&](uint64_t offset, const void* ptr, size_t size) {
memory_->SetMemory(offset, ptr, size);
});
Elf elf(memory_);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.interface() != nullptr);
ASSERT_TRUE(elf.gnu_debugdata_interface() == nullptr);
EXPECT_EQ(0x1acU, elf.interface()->gnu_debugdata_offset());
EXPECT_EQ(0x100U, elf.interface()->gnu_debugdata_size());
}
TEST_F(ElfTest, gnu_debugdata_init_fail64) {
TestInitGnuDebugdata<Elf64_Ehdr, Elf64_Shdr>(ELFCLASS64, EM_AARCH64, false,
[&](uint64_t offset, const void* ptr, size_t size) {
memory_->SetMemory(offset, ptr, size);
});
Elf elf(memory_);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.interface() != nullptr);
ASSERT_TRUE(elf.gnu_debugdata_interface() == nullptr);
EXPECT_EQ(0x200U, elf.interface()->gnu_debugdata_offset());
EXPECT_EQ(0x100U, elf.interface()->gnu_debugdata_size());
}
TEST_F(ElfTest, gnu_debugdata_init32) {
TestInitGnuDebugdata<Elf32_Ehdr, Elf32_Shdr>(ELFCLASS32, EM_ARM, true,
[&](uint64_t offset, const void* ptr, size_t size) {
memory_->SetMemory(offset, ptr, size);
});
Elf elf(memory_);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.interface() != nullptr);
ASSERT_TRUE(elf.gnu_debugdata_interface() == nullptr);
EXPECT_EQ(0x1acU, elf.interface()->gnu_debugdata_offset());
EXPECT_EQ(0x8cU, elf.interface()->gnu_debugdata_size());
elf.InitGnuDebugdata();
ASSERT_TRUE(elf.gnu_debugdata_interface() != nullptr);
}
TEST_F(ElfTest, gnu_debugdata_init64) {
TestInitGnuDebugdata<Elf64_Ehdr, Elf64_Shdr>(ELFCLASS64, EM_AARCH64, true,
[&](uint64_t offset, const void* ptr, size_t size) {
memory_->SetMemory(offset, ptr, size);
});
Elf elf(memory_);
ASSERT_TRUE(elf.Init());
ASSERT_TRUE(elf.interface() != nullptr);
ASSERT_TRUE(elf.gnu_debugdata_interface() == nullptr);
EXPECT_EQ(0x200U, elf.interface()->gnu_debugdata_offset());
EXPECT_EQ(0x90U, elf.interface()->gnu_debugdata_size());
elf.InitGnuDebugdata();
ASSERT_TRUE(elf.gnu_debugdata_interface() != nullptr);
}
class MockElf : public Elf {
public:
MockElf(Memory* memory) : Elf(memory) {}
virtual ~MockElf() = default;
void set_valid(bool valid) { valid_ = valid; }
void set_elf_interface(ElfInterface* interface) { interface_.reset(interface); }
};
TEST_F(ElfTest, rel_pc) {
MockElf elf(memory_);
ElfInterface* interface = new ElfInterface32(memory_);
elf.set_elf_interface(interface);
elf.set_valid(true);
interface->set_load_bias(0);
MapInfo map_info{.start = 0x1000, .end = 0x2000};
ASSERT_EQ(0x101U, elf.GetRelPc(0x1101, &map_info));
interface->set_load_bias(0x3000);
ASSERT_EQ(0x3101U, elf.GetRelPc(0x1101, &map_info));
elf.set_valid(false);
ASSERT_EQ(0x101U, elf.GetRelPc(0x1101, &map_info));
}
} // namespace unwindstack
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