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Use elf offset in signal step check.

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The function StepIfSignalHandler assumed that the rel_pc passed
to it was actually an elf offset. A new version of clang created a libc.so
that has a load bias, so tests unwinding through a signal handler
would fail on arm. On other ABIs, there is unwind information that could
be used instead, so the unwind still worked.

The fix is to subtract the load bias from the rel_pc to get an elf
offset to pass to the Register StepIfSignalHandler functions. Change all
of the Register funtions to make it clear what the first parameter means.

Add a unit test for this new code. Also, add an offline test for
this case.

Bug: 145683525

Test: Ran unit tests using the new clang and the old clang.
Change-Id: I3e249653b79bcad6d3a56411a7911fde4888e9d6
This commit is contained in:
Christopher Ferris 2019-12-04 13:37:11 -08:00
parent f7a6c4587f
commit f0c82e7bad
23 changed files with 128 additions and 23 deletions
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1
libunwindstack/Android.bp
View file

@ -251,6 +251,7 @@ cc_defaults {
"tests/files/offline/shared_lib_in_apk_arm64/*",
"tests/files/offline/shared_lib_in_apk_memory_only_arm64/*",
"tests/files/offline/shared_lib_in_apk_single_map_arm64/*",
"tests/files/offline/signal_load_bias_arm/*",
"tests/files/offline/straddle_arm/*",
"tests/files/offline/straddle_arm64/*",
],

7
libunwindstack/Elf.cpp
View file

@ -173,7 +173,12 @@ bool Elf::StepIfSignalHandler(uint64_t rel_pc, Regs* regs, Memory* process_memor
if (!valid_) {
return false;
}
return regs->StepIfSignalHandler(rel_pc, this, process_memory);
// Convert the rel_pc to an elf_offset.
if (rel_pc < static_cast<uint64_t>(load_bias_)) {
return false;
}
return regs->StepIfSignalHandler(rel_pc - load_bias_, this, process_memory);
}
// The relative pc is always relative to the start of the map from which it comes.

4
libunwindstack/RegsArm.cpp
View file

@ -127,12 +127,12 @@ Regs* RegsArm::CreateFromUcontext(void* ucontext) {
return regs;
}
bool RegsArm::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
bool RegsArm::StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) {
uint32_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->ReadFully(rel_pc, &data, sizeof(data))) {
if (!elf_memory->ReadFully(elf_offset, &data, sizeof(data))) {
return false;
}

4
libunwindstack/RegsArm64.cpp
View file

@ -126,12 +126,12 @@ Regs* RegsArm64::CreateFromUcontext(void* ucontext) {
return regs;
}
bool RegsArm64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
bool RegsArm64::StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) {
uint64_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->ReadFully(rel_pc, &data, sizeof(data))) {
if (!elf_memory->ReadFully(elf_offset, &data, sizeof(data))) {
return false;
}

4
libunwindstack/RegsMips.cpp
View file

@ -129,13 +129,13 @@ Regs* RegsMips::CreateFromUcontext(void* ucontext) {
return regs;
}
bool RegsMips::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
bool RegsMips::StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) {
uint64_t data;
uint64_t offset = 0;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->ReadFully(rel_pc, &data, sizeof(data))) {
if (!elf_memory->ReadFully(elf_offset, &data, sizeof(data))) {
return false;
}

4
libunwindstack/RegsMips64.cpp
View file

@ -127,12 +127,12 @@ Regs* RegsMips64::CreateFromUcontext(void* ucontext) {
return regs;
}
bool RegsMips64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
bool RegsMips64::StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) {
uint64_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->Read(rel_pc, &data, sizeof(data))) {
if (!elf_memory->Read(elf_offset, &data, sizeof(data))) {
return false;
}

4
libunwindstack/RegsX86.cpp
View file

@ -119,12 +119,12 @@ Regs* RegsX86::CreateFromUcontext(void* ucontext) {
return regs;
}
bool RegsX86::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
bool RegsX86::StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) {
uint64_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->ReadFully(rel_pc, &data, sizeof(data))) {
if (!elf_memory->ReadFully(elf_offset, &data, sizeof(data))) {
return false;
}

6
libunwindstack/RegsX86_64.cpp
View file

@ -139,17 +139,17 @@ Regs* RegsX86_64::CreateFromUcontext(void* ucontext) {
return regs;
}
bool RegsX86_64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
bool RegsX86_64::StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) {
uint64_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->ReadFully(rel_pc, &data, sizeof(data)) || data != 0x0f0000000fc0c748) {
if (!elf_memory->ReadFully(elf_offset, &data, sizeof(data)) || data != 0x0f0000000fc0c748) {
return false;
}
uint16_t data2;
if (!elf_memory->ReadFully(rel_pc + 8, &data2, sizeof(data2)) || data2 != 0x0f05) {
if (!elf_memory->ReadFully(elf_offset + 8, &data2, sizeof(data2)) || data2 != 0x0f05) {
return false;
}

2
libunwindstack/include/unwindstack/Regs.h
View file

@ -66,7 +66,7 @@ class Regs {
virtual uint64_t GetPcAdjustment(uint64_t rel_pc, Elf* elf) = 0;
virtual bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) = 0;
virtual bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) = 0;
virtual bool SetPcFromReturnAddress(Memory* process_memory) = 0;

2
libunwindstack/include/unwindstack/RegsArm.h
View file

@ -40,7 +40,7 @@ class RegsArm : public RegsImpl<uint32_t> {
bool SetPcFromReturnAddress(Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) override;
void IterateRegisters(std::function<void(const char*, uint64_t)>) override final;

2
libunwindstack/include/unwindstack/RegsArm64.h
View file

@ -40,7 +40,7 @@ class RegsArm64 : public RegsImpl<uint64_t> {
bool SetPcFromReturnAddress(Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) override;
void IterateRegisters(std::function<void(const char*, uint64_t)>) override final;

2
libunwindstack/include/unwindstack/RegsMips.h
View file

@ -40,7 +40,7 @@ class RegsMips : public RegsImpl<uint32_t> {
bool SetPcFromReturnAddress(Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) override;
void IterateRegisters(std::function<void(const char*, uint64_t)>) override final;

2
libunwindstack/include/unwindstack/RegsMips64.h
View file

@ -40,7 +40,7 @@ class RegsMips64 : public RegsImpl<uint64_t> {
bool SetPcFromReturnAddress(Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) override;
void IterateRegisters(std::function<void(const char*, uint64_t)>) override final;

2
libunwindstack/include/unwindstack/RegsX86.h
View file

@ -41,7 +41,7 @@ class RegsX86 : public RegsImpl<uint32_t> {
bool SetPcFromReturnAddress(Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) override;
void SetFromUcontext(x86_ucontext_t* ucontext);

2
libunwindstack/include/unwindstack/RegsX86_64.h
View file

@ -41,7 +41,7 @@ class RegsX86_64 : public RegsImpl<uint64_t> {
bool SetPcFromReturnAddress(Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) override;
bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) override;
void SetFromUcontext(x86_64_ucontext_t* ucontext);

15
libunwindstack/tests/ElfTest.cpp
View file

@ -104,6 +104,8 @@ class ElfTest : public ::testing::Test {
memory_->SetMemory(0x100, &phdr, sizeof(phdr));
}
void VerifyStepIfSignalHandler(uint64_t load_bias);
MemoryFake* memory_;
};
@ -281,7 +283,7 @@ TEST_F(ElfTest, rel_pc) {
ASSERT_EQ(0x101U, elf.GetRelPc(0x1101, &map_info));
}
TEST_F(ElfTest, step_in_signal_map) {
void ElfTest::VerifyStepIfSignalHandler(uint64_t load_bias) {
ElfFake elf(memory_);
RegsArm regs;
@ -290,6 +292,7 @@ TEST_F(ElfTest, step_in_signal_map) {
ElfInterfaceFake* interface = new ElfInterfaceFake(memory_);
elf.FakeSetInterface(interface);
elf.FakeSetLoadBias(load_bias);
memory_->SetData32(0x3000, 0xdf0027ad);
MemoryFake process_memory;
@ -299,12 +302,20 @@ TEST_F(ElfTest, step_in_signal_map) {
}
elf.FakeSetValid(true);
ASSERT_TRUE(elf.StepIfSignalHandler(0x3000, &regs, &process_memory));
ASSERT_TRUE(elf.StepIfSignalHandler(0x3000 + load_bias, &regs, &process_memory));
EXPECT_EQ(ERROR_NONE, elf.GetLastErrorCode());
EXPECT_EQ(15U, regs.pc());
EXPECT_EQ(13U, regs.sp());
}
TEST_F(ElfTest, step_in_signal_map) {
VerifyStepIfSignalHandler(0);
}
TEST_F(ElfTest, step_in_signal_map_non_zero_load_bias) {
VerifyStepIfSignalHandler(0x1000);
}
class ElfInterfaceMock : public ElfInterface {
public:
ElfInterfaceMock(Memory* memory) : ElfInterface(memory) {}

68
libunwindstack/tests/UnwindOfflineTest.cpp
View file

@ -1629,4 +1629,72 @@ TEST_F(UnwindOfflineTest, eh_frame_bias_x86) {
EXPECT_EQ(0xfffe1d74ULL, unwinder.frames()[10].sp);
}
TEST_F(UnwindOfflineTest, signal_load_bias_arm) {
ASSERT_NO_FATAL_FAILURE(Init("signal_load_bias_arm/", ARCH_ARM));
Unwinder unwinder(128, maps_.get(), regs_.get(), process_memory_);
unwinder.Unwind();
std::string frame_info(DumpFrames(unwinder));
ASSERT_EQ(17U, unwinder.NumFrames()) << "Unwind:\n" << frame_info;
EXPECT_EQ(
" #00 pc 0029ef9e libunwindstack_unit_test (SignalInnerFunction+10)\n"
" #01 pc 0029efa7 libunwindstack_unit_test (SignalMiddleFunction+2)\n"
" #02 pc 0029efaf libunwindstack_unit_test (SignalOuterFunction+2)\n"
" #03 pc 002a280b libunwindstack_unit_test (unwindstack::SignalCallerHandler(int, "
"siginfo*, void*)+10)\n"
" #04 pc 00058bd4 libc.so (__restore)\n"
" #05 pc 0029f01e libunwindstack_unit_test (InnerFunction+106)\n"
" #06 pc 0029f633 libunwindstack_unit_test (MiddleFunction+16)\n"
" #07 pc 0029f64b libunwindstack_unit_test (OuterFunction+16)\n"
" #08 pc 002a1711 libunwindstack_unit_test (unwindstack::RemoteThroughSignal(int, unsigned "
"int)+260)\n"
" #09 pc 002a1603 libunwindstack_unit_test "
"(unwindstack::UnwindTest_remote_through_signal_Test::TestBody()+10)\n"
" #10 pc 002c8fe3 libunwindstack_unit_test (testing::Test::Run()+130)\n"
" #11 pc 002c9b25 libunwindstack_unit_test (testing::TestInfo::Run()+184)\n"
" #12 pc 002c9e27 libunwindstack_unit_test (testing::TestSuite::Run()+202)\n"
" #13 pc 002d193d libunwindstack_unit_test "
"(testing::internal::UnitTestImpl::RunAllTests()+660)\n"
" #14 pc 002d160b libunwindstack_unit_test (testing::UnitTest::Run()+134)\n"
" #15 pc 002de035 libunwindstack_unit_test (IsolateMain+680)\n"
" #16 pc 00058155 libc.so (__libc_init+68)\n",
frame_info);
EXPECT_EQ(0xb6955f9eULL, unwinder.frames()[0].pc);
EXPECT_EQ(0xf2790ce8ULL, unwinder.frames()[0].sp);
EXPECT_EQ(0xb6955fa7ULL, unwinder.frames()[1].pc);
EXPECT_EQ(0xf2790ce8ULL, unwinder.frames()[1].sp);
EXPECT_EQ(0xb6955fafULL, unwinder.frames()[2].pc);
EXPECT_EQ(0xf2790cf0ULL, unwinder.frames()[2].sp);
EXPECT_EQ(0xb695980bULL, unwinder.frames()[3].pc);
EXPECT_EQ(0xf2790cf8ULL, unwinder.frames()[3].sp);
EXPECT_EQ(0xf23febd4ULL, unwinder.frames()[4].pc);
EXPECT_EQ(0xf2790d10ULL, unwinder.frames()[4].sp);
EXPECT_EQ(0xb695601eULL, unwinder.frames()[5].pc);
EXPECT_EQ(0xffe67798ULL, unwinder.frames()[5].sp);
EXPECT_EQ(0xb6956633ULL, unwinder.frames()[6].pc);
EXPECT_EQ(0xffe67890ULL, unwinder.frames()[6].sp);
EXPECT_EQ(0xb695664bULL, unwinder.frames()[7].pc);
EXPECT_EQ(0xffe678a0ULL, unwinder.frames()[7].sp);
EXPECT_EQ(0xb6958711ULL, unwinder.frames()[8].pc);
EXPECT_EQ(0xffe678b0ULL, unwinder.frames()[8].sp);
EXPECT_EQ(0xb6958603ULL, unwinder.frames()[9].pc);
EXPECT_EQ(0xffe67ac8ULL, unwinder.frames()[9].sp);
EXPECT_EQ(0xb697ffe3ULL, unwinder.frames()[10].pc);
EXPECT_EQ(0xffe67ad8ULL, unwinder.frames()[10].sp);
EXPECT_EQ(0xb6980b25ULL, unwinder.frames()[11].pc);
EXPECT_EQ(0xffe67ae8ULL, unwinder.frames()[11].sp);
EXPECT_EQ(0xb6980e27ULL, unwinder.frames()[12].pc);
EXPECT_EQ(0xffe67b18ULL, unwinder.frames()[12].sp);
EXPECT_EQ(0xb698893dULL, unwinder.frames()[13].pc);
EXPECT_EQ(0xffe67b48ULL, unwinder.frames()[13].sp);
EXPECT_EQ(0xb698860bULL, unwinder.frames()[14].pc);
EXPECT_EQ(0xffe67bb0ULL, unwinder.frames()[14].sp);
EXPECT_EQ(0xb6995035ULL, unwinder.frames()[15].pc);
EXPECT_EQ(0xffe67bd0ULL, unwinder.frames()[15].sp);
EXPECT_EQ(0xf23fe155ULL, unwinder.frames()[16].pc);
EXPECT_EQ(0xffe67d10ULL, unwinder.frames()[16].sp);
}
} // namespace unwindstack

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libunwindstack/tests/files/offline/signal_load_bias_arm/libc.so Normal file
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libunwindstack/tests/files/offline/signal_load_bias_arm/libunwindstack_unit_test Normal file
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4
libunwindstack/tests/files/offline/signal_load_bias_arm/maps.txt Normal file
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@ -0,0 +1,4 @@
b66b7000-b670c000 r--p 0 00:00 0 libunwindstack_unit_test
b670c000-b69a8000 r-xp 54000 00:00 0 libunwindstack_unit_test
f23a6000-f23d0000 r--p 0 00:00 0 libc.so
f23d0000-f2451000 r-xp 29000 00:00 0 libc.so

16
libunwindstack/tests/files/offline/signal_load_bias_arm/regs.txt Normal file
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@ -0,0 +1,16 @@
r0: b69b7c84
r1: 1
r2: 1
r3: 1
r4: f1e52bd0
r5: f1e11000
r6: f1e52bd0
r7: f1e52a38
r8: f1e11000
r9: 5de82a8f
r10: f1e06030
r11: f1e6d080
ip: ffe67a88
sp: f2790ce8
lr: b6955fab
pc: b6955f9e

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libunwindstack/tests/files/offline/signal_load_bias_arm/stack0.data Normal file
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libunwindstack/tests/files/offline/signal_load_bias_arm/stack1.data Normal file
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