From 7138232f576a4f8941120239e5912501fb568ec7 Mon Sep 17 00:00:00 2001 From: Christopher Ferris Date: Fri, 30 Aug 2019 14:02:19 -0700 Subject: [PATCH] Add test of undefined return address. Add a specific test that __libc_init is the last frame in a stack when run on device. In addition, it verifies that the return address register is marked as undefined given the unwind. Bug: 140008396 Test: New unit test passes on arm/arm64 (taimen device). Test: New unit test passes on x86 (cuttlefish). Test: New unit test passes on x86_64 (modified bionic/tests/run-on-host.sh) Change-Id: Iefc151a7dbf52ab083c2bb78bad3d38b4e9e1254 --- libunwindstack/Android.bp | 1 + libunwindstack/Unwinder.cpp | 4 +- libunwindstack/include/unwindstack/Unwinder.h | 6 +- .../tests/VerifyBionicTerminationTest.cpp | 124 ++++++++++++++++++ 4 files changed, 130 insertions(+), 5 deletions(-) create mode 100644 libunwindstack/tests/VerifyBionicTerminationTest.cpp diff --git a/libunwindstack/Android.bp b/libunwindstack/Android.bp index 73237e6f2..14246aeb2 100644 --- a/libunwindstack/Android.bp +++ b/libunwindstack/Android.bp @@ -211,6 +211,7 @@ cc_test { "tests/UnwindOfflineTest.cpp", "tests/UnwindTest.cpp", "tests/UnwinderTest.cpp", + "tests/VerifyBionicTerminationTest.cpp", ], cflags: [ diff --git a/libunwindstack/Unwinder.cpp b/libunwindstack/Unwinder.cpp index 755648297..0b9b85c65 100644 --- a/libunwindstack/Unwinder.cpp +++ b/libunwindstack/Unwinder.cpp @@ -309,7 +309,7 @@ void Unwinder::Unwind(const std::vector* initial_map_names_to_skip, } } -std::string Unwinder::FormatFrame(const FrameData& frame) { +std::string Unwinder::FormatFrame(const FrameData& frame) const { std::string data; if (regs_->Is32Bit()) { data += android::base::StringPrintf(" #%02zu pc %08" PRIx64, frame.num, frame.rel_pc); @@ -355,7 +355,7 @@ std::string Unwinder::FormatFrame(const FrameData& frame) { return data; } -std::string Unwinder::FormatFrame(size_t frame_num) { +std::string Unwinder::FormatFrame(size_t frame_num) const { if (frame_num >= frames_.size()) { return ""; } diff --git a/libunwindstack/include/unwindstack/Unwinder.h b/libunwindstack/include/unwindstack/Unwinder.h index 52b3578d8..11ad9de6f 100644 --- a/libunwindstack/include/unwindstack/Unwinder.h +++ b/libunwindstack/include/unwindstack/Unwinder.h @@ -77,7 +77,7 @@ class Unwinder { void Unwind(const std::vector* initial_map_names_to_skip = nullptr, const std::vector* map_suffixes_to_ignore = nullptr); - size_t NumFrames() { return frames_.size(); } + size_t NumFrames() const { return frames_.size(); } const std::vector& frames() { return frames_; } @@ -87,8 +87,8 @@ class Unwinder { return frames; } - std::string FormatFrame(size_t frame_num); - std::string FormatFrame(const FrameData& frame); + std::string FormatFrame(size_t frame_num) const; + std::string FormatFrame(const FrameData& frame) const; void SetJitDebug(JitDebug* jit_debug, ArchEnum arch); diff --git a/libunwindstack/tests/VerifyBionicTerminationTest.cpp b/libunwindstack/tests/VerifyBionicTerminationTest.cpp new file mode 100644 index 000000000..6a3e91a2a --- /dev/null +++ b/libunwindstack/tests/VerifyBionicTerminationTest.cpp @@ -0,0 +1,124 @@ +/* + * Copyright (C) 2019 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. + */ + +#define _GNU_SOURCE 1 +#include +#include + +#include + +#if defined(__BIONIC__) + +#include + +#include +#include +#include +#include +#include +#include + +// This test is specific to bionic to verify that __libc_init is +// properly setting the return address to undefined so that the +// unwind properly terminates. + +namespace unwindstack { + +static std::string DumpFrames(const UnwinderFromPid& unwinder) { + std::string unwind; + for (size_t i = 0; i < unwinder.NumFrames(); i++) { + unwind += unwinder.FormatFrame(i) + '\n'; + } + return unwind; +} + +static DwarfLocationEnum GetReturnAddressLocation(uint64_t rel_pc, DwarfSection* section) { + if (section == nullptr) { + return DWARF_LOCATION_INVALID; + } + + const DwarfFde* fde = section->GetFdeFromPc(rel_pc); + if (fde == nullptr || fde->cie == nullptr) { + return DWARF_LOCATION_INVALID; + } + dwarf_loc_regs_t regs; + if (!section->GetCfaLocationInfo(rel_pc, fde, ®s)) { + return DWARF_LOCATION_INVALID; + } + + auto reg_entry = regs.find(fde->cie->return_address_register); + if (reg_entry == regs.end()) { + return DWARF_LOCATION_INVALID; + } + return reg_entry->second.type; +} + +static void VerifyReturnAddress(const FrameData& frame) { + // Now go and find information about the register data and verify that the relative pc results in + // an undefined register. + Elf elf(Memory::CreateFileMemory(frame.map_name, 0).release()); + ASSERT_TRUE(elf.Init()) << "Failed to init elf object from " << frame.map_name; + ASSERT_TRUE(elf.valid()) << "Elf " << frame.map_name << " is not valid."; + ElfInterface* interface = elf.interface(); + + // Only check the eh_frame and the debug_frame since the undefined register + // is set using a cfi directive. + // Check debug_frame first, then eh_frame since debug_frame always + // contains the most specific data. + DwarfLocationEnum location = GetReturnAddressLocation(frame.rel_pc, interface->debug_frame()); + if (location == DWARF_LOCATION_UNDEFINED) { + return; + } + + location = GetReturnAddressLocation(frame.rel_pc, interface->eh_frame()); + ASSERT_EQ(DWARF_LOCATION_UNDEFINED, location); +} + +// This test assumes that it starts from the main thread, and that the +// libc.so on device will include symbols so that function names can +// be resolved. +TEST(VerifyBionicTermination, local_terminate) { + std::unique_ptr regs(Regs::CreateFromLocal()); + + UnwinderFromPid unwinder(512, getpid()); + ASSERT_TRUE(unwinder.Init(regs->Arch())); + unwinder.SetRegs(regs.get()); + + RegsGetLocal(regs.get()); + unwinder.Unwind(); + ASSERT_LT(0U, unwinder.NumFrames()); + + SCOPED_TRACE(DumpFrames(unwinder)); + + // Look for the frame that includes __libc_init, there should only + // be one and it should be the last. + bool found = false; + const std::vector& frames = unwinder.frames(); + for (size_t i = 0; i < unwinder.NumFrames(); i++) { + const FrameData& frame = frames[i]; + if (frame.function_name == "__libc_init" && !frame.map_name.empty() && + std::string("libc.so") == basename(frame.map_name.c_str())) { + ASSERT_EQ(unwinder.NumFrames(), i + 1) << "__libc_init is not last frame."; + ASSERT_NO_FATAL_FAILURE(VerifyReturnAddress(frame)); + found = true; + } + } + ASSERT_TRUE(found) << "Unable to find libc.so:__libc_init frame\n"; +} + +} // namespace unwindstack + +#endif