123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236 |
- // Copyright 2019 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/immediate_crash.h"
- #include <stdint.h>
- #include "base/base_paths.h"
- #include "base/clang_profiling_buildflags.h"
- #include "base/containers/span.h"
- #include "base/files/file_path.h"
- #include "base/path_service.h"
- #include "base/ranges/algorithm.h"
- #include "base/scoped_native_library.h"
- #include "base/strings/string_number_conversions.h"
- #include "build/build_config.h"
- #include "build/buildflag.h"
- #include "testing/gtest/include/gtest/gtest.h"
- #include "third_party/abseil-cpp/absl/types/optional.h"
- namespace base {
- namespace {
- // If IMMEDIATE_CRASH() is not treated as noreturn by the compiler, the compiler
- // will complain that not all paths through this function return a value.
- [[maybe_unused]] int TestImmediateCrashTreatedAsNoReturn() {
- IMMEDIATE_CRASH();
- }
- #if defined(ARCH_CPU_X86_FAMILY)
- // This is tricksy and false, since x86 instructions are not all one byte long,
- // but there is no better alternative short of implementing an x86 instruction
- // decoder.
- using Instruction = uint8_t;
- // https://software.intel.com/en-us/download/intel-64-and-ia-32-architectures-sdm-combined-volumes-1-2a-2b-2c-2d-3a-3b-3c-3d-and-4
- // Look for RET opcode (0xc3). Note that 0xC3 is a substring of several
- // other opcodes (VMRESUME, MOVNTI), and can also be encoded as part of an
- // argument to another opcode. None of these other cases are expected to be
- // present, so a simple byte scan should be Good Enough™.
- constexpr Instruction kRet = 0xc3;
- // INT3 ; UD2
- constexpr Instruction kRequiredBody[] = {0xcc, 0x0f, 0x0b};
- constexpr Instruction kOptionalFooter[] = {};
- #elif defined(ARCH_CPU_ARMEL)
- using Instruction = uint16_t;
- // T32 opcode reference: https://developer.arm.com/docs/ddi0487/latest
- // Actually BX LR, canonical encoding:
- constexpr Instruction kRet = 0x4770;
- // BKPT #0; UDF #0
- constexpr Instruction kRequiredBody[] = {0xbe00, 0xde00};
- constexpr Instruction kOptionalFooter[] = {};
- #elif defined(ARCH_CPU_ARM64)
- using Instruction = uint32_t;
- // A64 opcode reference: https://developer.arm.com/docs/ddi0487/latest
- // Use an enum here rather than separate constexpr vars because otherwise some
- // of the vars will end up unused on each platform, upsetting
- // -Wunused-const-variable.
- enum : Instruction {
- // There are multiple valid encodings of return (which is really a special
- // form of branch). This is the one clang seems to use:
- kRet = 0xd65f03c0,
- kBrk0 = 0xd4200000,
- kBrk1 = 0xd4200020,
- kBrkF000 = 0xd43e0000,
- kHlt0 = 0xd4400000,
- };
- #if BUILDFLAG(IS_WIN)
- constexpr Instruction kRequiredBody[] = {kBrkF000, kBrk1};
- constexpr Instruction kOptionalFooter[] = {};
- #elif BUILDFLAG(IS_MAC)
- constexpr Instruction kRequiredBody[] = {kBrk0, kHlt0};
- // Some clangs emit a BRK #1 for __builtin_unreachable(), but some do not, so
- // it is allowed but not required to occur.
- constexpr Instruction kOptionalFooter[] = {kBrk1};
- #else
- constexpr Instruction kRequiredBody[] = {kBrk0, kHlt0};
- constexpr Instruction kOptionalFooter[] = {};
- #endif
- #endif
- // This function loads a shared library that defines two functions,
- // TestFunction1 and TestFunction2. It then returns the bytes of the body of
- // whichever of those functions happens to come first in the library.
- void GetTestFunctionInstructions(std::vector<Instruction>* body) {
- FilePath helper_library_path;
- #if !BUILDFLAG(IS_ANDROID) && !BUILDFLAG(IS_FUCHSIA)
- // On Android M, DIR_EXE == /system/bin when running base_unittests.
- // On Fuchsia, NativeLibrary understands the native convention that libraries
- // are not colocated with the binary.
- ASSERT_TRUE(PathService::Get(DIR_EXE, &helper_library_path));
- #endif
- helper_library_path = helper_library_path.AppendASCII(
- GetNativeLibraryName("immediate_crash_test_helper"));
- #if BUILDFLAG(IS_ANDROID) && defined(COMPONENT_BUILD)
- helper_library_path = helper_library_path.ReplaceExtension(".cr.so");
- #endif
- ScopedNativeLibrary helper_library(helper_library_path);
- ASSERT_TRUE(helper_library.is_valid())
- << "shared library load failed: "
- << helper_library.GetError()->ToString();
- void* a = helper_library.GetFunctionPointer("TestFunction1");
- ASSERT_TRUE(a);
- void* b = helper_library.GetFunctionPointer("TestFunction2");
- ASSERT_TRUE(b);
- #if defined(ARCH_CPU_ARMEL)
- // Routines loaded from a shared library will have the LSB in the pointer set
- // if encoded as T32 instructions. The rest of this test assumes T32.
- ASSERT_TRUE(reinterpret_cast<uintptr_t>(a) & 0x1)
- << "Expected T32 opcodes but found A32 opcodes instead.";
- ASSERT_TRUE(reinterpret_cast<uintptr_t>(b) & 0x1)
- << "Expected T32 opcodes but found A32 opcodes instead.";
- // Mask off the lowest bit.
- a = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(a) & ~uintptr_t{0x1});
- b = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(b) & ~uintptr_t{0x1});
- #endif
- // There are two identical test functions starting at a and b, which may
- // occur in the library in either order. Grab whichever one comes first,
- // and use the address of the other to figure out where it ends.
- const Instruction* const start = static_cast<Instruction*>(std::min(a, b));
- const Instruction* const end = static_cast<Instruction*>(std::max(a, b));
- for (const Instruction& instruction : make_span(start, end))
- body->push_back(instruction);
- }
- absl::optional<std::vector<Instruction>> ExpectImmediateCrashInvocation(
- std::vector<Instruction> instructions) {
- auto iter = instructions.begin();
- for (const auto inst : kRequiredBody) {
- if (iter == instructions.end())
- return absl::nullopt;
- EXPECT_EQ(inst, *iter);
- iter++;
- }
- return absl::make_optional(
- std::vector<Instruction>(iter, instructions.end()));
- }
- std::vector<Instruction> MaybeSkipOptionalFooter(
- std::vector<Instruction> instructions) {
- auto iter = instructions.begin();
- for (const auto inst : kOptionalFooter) {
- if (iter == instructions.end() || *iter != inst)
- break;
- iter++;
- }
- return std::vector<Instruction>(iter, instructions.end());
- }
- #if BUILDFLAG(USE_CLANG_COVERAGE) || BUILDFLAG(CLANG_PROFILING)
- bool MatchPrefix(const std::vector<Instruction>& haystack,
- const base::span<const Instruction>& needle) {
- for (size_t i = 0; i < needle.size(); i++) {
- if (i >= haystack.size() || needle[i] != haystack[i])
- return false;
- }
- return true;
- }
- std::vector<Instruction> DropUntilMatch(
- std::vector<Instruction> haystack,
- const base::span<const Instruction>& needle) {
- while (!haystack.empty() && !MatchPrefix(haystack, needle))
- haystack.erase(haystack.begin());
- return haystack;
- }
- #endif // USE_CLANG_COVERAGE || BUILDFLAG(CLANG_PROFILING)
- std::vector<Instruction> MaybeSkipCoverageHook(
- std::vector<Instruction> instructions) {
- #if BUILDFLAG(USE_CLANG_COVERAGE) || BUILDFLAG(CLANG_PROFILING)
- // Warning: it is not illegal for the entirety of the expected crash sequence
- // to appear as a subsequence of the coverage hook code. If that happens, this
- // code will falsely exit early, having not found the real expected crash
- // sequence, so this may not adequately ensure that the immediate crash
- // sequence is present. We do check when not under coverage, at least.
- return DropUntilMatch(instructions, base::make_span(kRequiredBody));
- #else
- return instructions;
- #endif // USE_CLANG_COVERAGE || BUILDFLAG(CLANG_PROFILING)
- }
- } // namespace
- // Attempts to verify the actual instructions emitted by IMMEDIATE_CRASH().
- // While the test results are highly implementation-specific, this allows macro
- // changes (e.g. CLs like https://crrev.com/671123) to be verified using the
- // trybots/waterfall, without having to build and disassemble Chrome on
- // multiple platforms. This makes it easier to evaluate changes to
- // IMMEDIATE_CRASH() against its requirements (e.g. size of emitted sequence,
- // whether or not multiple IMMEDIATE_CRASH sequences can be folded together, et
- // cetera). Please see immediate_crash.h for more details about the
- // requirements.
- //
- // Note that C++ provides no way to get the size of a function. Instead, the
- // test relies on a shared library which defines only two functions and assumes
- // the two functions will be laid out contiguously as a heuristic for finding
- // the size of the function.
- TEST(ImmediateCrashTest, ExpectedOpcodeSequence) {
- std::vector<Instruction> body;
- ASSERT_NO_FATAL_FAILURE(GetTestFunctionInstructions(&body));
- SCOPED_TRACE(HexEncode(body.data(), body.size() * sizeof(Instruction)));
- auto it = ranges::find(body, kRet);
- ASSERT_NE(body.end(), it) << "Failed to find return opcode";
- it++;
- body = std::vector<Instruction>(it, body.end());
- absl::optional<std::vector<Instruction>> result = MaybeSkipCoverageHook(body);
- result = ExpectImmediateCrashInvocation(result.value());
- result = MaybeSkipOptionalFooter(result.value());
- result = MaybeSkipCoverageHook(result.value());
- result = ExpectImmediateCrashInvocation(result.value());
- ASSERT_TRUE(result);
- }
- } // namespace base
|