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S2EExecutor.cpp
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///
/// Copyright (C) 2010-2016, Dependable Systems Laboratory, EPFL
/// Copyright (C) 2014-2019, Cyberhaven
///
/// Permission is hereby granted, free of charge, to any person obtaining a copy
/// of this software and associated documentation files (the "Software"), to deal
/// in the Software without restriction, including without limitation the rights
/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
/// copies of the Software, and to permit persons to whom the Software is
/// furnished to do so, subject to the following conditions:
///
/// The above copyright notice and this permission notice shall be included in all
/// copies or substantial portions of the Software.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
/// SOFTWARE.
///
#include <s2e/CorePlugin.h>
#include <s2e/S2E.h>
#include <s2e/S2EExecutionState.h>
#include <s2e/S2EExecutor.h>
#include <s2e/S2EExternalDispatcher.h>
#include <s2e/SymbolicHardwareHook.h>
#include <s2e/Utils.h>
#include <s2e/cpu.h>
#include <s2e/s2e_config.h>
#include <s2e/S2EDeviceState.h>
#include <s2e/S2EStatsTracker.h>
#include <s2e/s2e_libcpu.h>
#include <llvm/IR/Constants.h>
#include <llvm/IR/DataLayout.h>
#include <llvm/IR/DerivedTypes.h>
#include <llvm/IR/Function.h>
#include <llvm/IR/Instructions.h>
#include <llvm/IR/LegacyPassManager.h>
#include <llvm/IR/Module.h>
#include <llvm/Support/CommandLine.h>
#include <llvm/Support/DynamicLibrary.h>
#include <llvm/Support/Process.h>
#include <llvm/Support/FileSystem.h>
#include <llvm/Support/Path.h>
#include <llvm/ADT/IntervalMap.h>
#include <klee/ExternalDispatcher.h>
#include <klee/Memory.h>
#include <klee/Searcher.h>
#include <klee/Solver.h>
#include <klee/SolverFactory.h>
#include <klee/Stats/CoreStats.h>
#include <klee/Stats/TimerStatIncrementer.h>
#include <klee/util/ExprTemplates.h>
#include <tcg/tcg-llvm.h>
#include <glib.h>
#include <sstream>
#include <vector>
#ifdef WIN32
#include <windows.h>
#else
#include <sys/mman.h>
#endif
#include <functional>
//#define S2E_DEBUG_INSTRUCTIONS
//#define S2E_DEBUG_MEMOBJECT_NAME
//#define S2E_TRACE_EFLAGS
//#define FORCE_CONCRETIZATION
using namespace std;
using namespace llvm;
using namespace klee;
// clang-format off
namespace {
// This should be true by default, because otherwise overheads are way too high.
// Drawback is that execution is not fully consistent by default.
cl::opt<bool>
StateSharedMemory("state-shared-memory",
cl::desc("Allow unimportant memory regions (like video RAM) to be shared between states"),
cl::init(true));
cl::opt<bool>
FlushTBsOnStateSwitch("flush-tbs-on-state-switch",
cl::desc("Flush translation blocks when switching states -"
" disabling leads to faster but possibly incorrect execution"),
cl::init(true));
//The default is true for two reasons:
//1. Symbolic addresses are very expensive to handle
//2. There is lazy forking which will eventually enumerate
//all possible addresses.
//Overall, we have more path explosion, but at least execution
//does not get stuck in various places.
cl::opt<bool>
ForkOnSymbolicAddress("fork-on-symbolic-address",
cl::desc("Fork on each memory access with symbolic address"),
cl::init(true));
cl::opt<bool>
ConcretizeIoAddress("concretize-io-address",
cl::desc("Concretize symbolic I/O addresses"),
cl::init(true));
//XXX: Works for MMIO only, add support for port I/O
cl::opt<bool>
ConcretizeIoWrites("concretize-io-writes",
cl::desc("Concretize symbolic I/O writes"),
cl::init(true));
cl::opt<bool>
PrintLLVMInstructions("print-llvm-instructions",
cl::desc("Traces all LLVM instructions sent to KLEE"),
cl::init(false));
cl::opt<bool>
EnableForking("enable-forking",
cl::desc("Enable forking of S2E states"),
cl::init(true));
cl::opt<bool>
VerboseFork("verbose-fork-info",
cl::desc("Print detailed information on forks"),
cl::init(false));
cl::opt<bool>
VerboseStateSwitching("verbose-state-switching",
cl::desc("Print detailed information on state switches"),
cl::init(false));
cl::opt<bool>
VerboseTbFinalize("verbose-tb-finalize",
cl::desc("Print detailed information when finalizing a partially-completed TB"),
cl::init(false));
cl::opt<bool>
UseFastHelpers("use-fast-helpers",
cl::desc("Replaces LLVM bitcode with fast symbolic-aware equivalent native helpers"),
cl::init(false));
cl::opt<unsigned>
ClockSlowDown("clock-slow-down",
cl::desc("Slow down factor when interpreting LLVM code"),
cl::init(101));
cl::opt<unsigned>
ClockSlowDownConcrete("clock-slow-down-concrete",
cl::desc("Slow down factor when running concrete code"),
cl::init(1));
cl::opt<unsigned>
ClockSlowDownFastHelpers("clock-slow-down-fast-helpers",
cl::desc("Slow down factor when interpreting LLVM code and using fast helpers"),
cl::init(11));
cl::opt<bool>
SinglePathMode("single-path-mode",
cl::desc("Faster TLB, but forces single path execution"),
cl::init(false));
cl::opt<bool> NoTruncateSourceLines("no-truncate-source-lines",
cl::desc("Don't truncate long lines in the output source"));
cl::opt<bool> OutputSource("output-source", cl::desc("Write the assembly for the final transformed source"),
cl::init(true));
cl::opt<bool> OutputModule("output-module", cl::desc("Write the bitcode for the final transformed module"),
cl::init(false));
}
//The logs may be flooded with messages when switching execution mode.
//This option allows disabling printing mode switches.
cl::opt<bool>
PrintModeSwitch("print-mode-switch",
cl::desc("Print message when switching from symbolic to concrete and vice versa"),
cl::init(false));
cl::opt<bool>
PrintForkingStatus("print-forking-status",
cl::desc("Print message when enabling/disabling forking."),
cl::init(false));
cl::opt<bool>
VerboseStateDeletion("verbose-state-deletion",
cl::desc("Print detailed information on state deletion"),
cl::init(false));
cl::opt<bool>
DebugConstraints("debug-constraints",
cl::desc("Check that added constraints are satisfiable"),
cl::init(false));
extern cl::opt<bool> UseExprSimplifier;
extern "C" {
int g_s2e_fork_on_symbolic_address = 0;
int g_s2e_concretize_io_addresses = 1;
int g_s2e_concretize_io_writes = 1;
// XXX: the following should be thread-local when
// we implement support for multi-cores in the guest
// Tells the main loop whether it is ok to call
// the native call directly, without going through
// several layers of indirection in S2EExecutor.
// This variable is set when all registers are concrete
// and symbolic execution is not forced for the current tb.
int g_s2e_fast_concrete_invocation = 0;
// Direct access to the execution function.
// Avoids going through a wrapper.
se_libcpu_tb_exec_t se_libcpu_tb_exec = &s2e::S2EExecutor::executeTranslationBlockFast;
char *g_s2e_running_exception_emulation_code = nullptr;
se_do_interrupt_all_t g_s2e_do_interrupt_all = &s2e::S2EExecutor::doInterruptAll;
//Shortcut to speed up access to the dirty mask (it is always concrete)
uintptr_t g_se_dirty_mask_addend = 0;
void s2e_print_instructions(int v);
void s2e_print_instructions(int v) {
PrintLLVMInstructions = v;
}
int g_s2e_single_path_mode = 0;
}
// clang-format on
namespace s2e {
/* Global array to hold tb function arguments */
volatile void *tb_function_args[3];
S2EExecutor::S2EExecutor(S2E *s2e, TCGLLVMTranslator *translator)
: Executor(translator->getContext()), m_s2e(s2e), m_llvmTranslator(translator), m_executeAlwaysKlee(false),
m_forkProcTerminateCurrentState(false), m_inLoadBalancing(false) {
delete externalDispatcher;
externalDispatcher = new S2EExternalDispatcher();
LLVMContext &ctx = m_llvmTranslator->getContext();
/* Define globally accessible functions */
#define __DEFINE_EXT_FUNCTION(name) llvm::sys::DynamicLibrary::AddSymbol(#name, (void *) name);
#define __DEFINE_EXT_VARIABLE(name) llvm::sys::DynamicLibrary::AddSymbol(#name, (void *) &name);
//__DEFINE_EXT_FUNCTION(raise_exception)
//__DEFINE_EXT_FUNCTION(raise_exception_err)
helper_register_symbols();
__DEFINE_EXT_VARIABLE(g_s2e_concretize_io_addresses)
__DEFINE_EXT_VARIABLE(g_s2e_concretize_io_writes)
__DEFINE_EXT_VARIABLE(g_s2e_fork_on_symbolic_address)
__DEFINE_EXT_VARIABLE(g_s2e_before_memory_access_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_after_memory_access_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_translate_block_start_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_translate_block_end_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_translate_instruction_start_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_translate_jump_start_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_translate_lea_rip_relative_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_translate_instruction_end_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_translate_register_access_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_exception_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_page_fault_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_tlb_miss_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_port_access_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_privilege_change_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_on_page_directory_change_signals_count)
__DEFINE_EXT_VARIABLE(g_s2e_enable_mmio_checks)
__DEFINE_EXT_VARIABLE(s2e_kill_state)
__DEFINE_EXT_FUNCTION(cpu_interrupt_handler)
__DEFINE_EXT_FUNCTION(exit)
__DEFINE_EXT_FUNCTION(fprintf)
__DEFINE_EXT_FUNCTION(sprintf)
__DEFINE_EXT_FUNCTION(fputc)
__DEFINE_EXT_FUNCTION(fwrite)
__DEFINE_EXT_FUNCTION(memset)
__DEFINE_EXT_FUNCTION(memcpy)
__DEFINE_EXT_FUNCTION(memmove)
__DEFINE_EXT_FUNCTION(floatx80_to_float64)
__DEFINE_EXT_FUNCTION(float64_to_floatx80)
__DEFINE_EXT_FUNCTION(int32_to_floatx80)
__DEFINE_EXT_FUNCTION(int64_to_floatx80)
__DEFINE_EXT_FUNCTION(floatx80_mul)
__DEFINE_EXT_FUNCTION(floatx80_add)
__DEFINE_EXT_FUNCTION(floatx80_compare_quiet)
__DEFINE_EXT_FUNCTION(set_float_rounding_mode)
__DEFINE_EXT_FUNCTION(cpu_x86_handle_mmu_fault)
__DEFINE_EXT_FUNCTION(cpu_x86_update_cr0)
__DEFINE_EXT_FUNCTION(cpu_x86_update_cr3)
__DEFINE_EXT_FUNCTION(cpu_x86_update_cr4)
__DEFINE_EXT_FUNCTION(cpu_x86_cpuid)
__DEFINE_EXT_FUNCTION(cpu_outb)
__DEFINE_EXT_FUNCTION(cpu_outw)
__DEFINE_EXT_FUNCTION(cpu_outl)
__DEFINE_EXT_FUNCTION(cpu_inb)
__DEFINE_EXT_FUNCTION(cpu_inw)
__DEFINE_EXT_FUNCTION(cpu_inl)
__DEFINE_EXT_FUNCTION(cpu_restore_state)
__DEFINE_EXT_FUNCTION(cpu_abort)
__DEFINE_EXT_FUNCTION(cpu_loop_exit)
__DEFINE_EXT_FUNCTION(cpu_loop_exit_restore)
__DEFINE_EXT_FUNCTION(cpu_get_tsc)
__DEFINE_EXT_FUNCTION(cpu_exit)
__DEFINE_EXT_FUNCTION(hw_breakpoint_insert)
__DEFINE_EXT_FUNCTION(hw_breakpoint_remove)
__DEFINE_EXT_FUNCTION(check_hw_breakpoints)
__DEFINE_EXT_FUNCTION(tlb_flush_page)
__DEFINE_EXT_FUNCTION(tlb_flush)
__DEFINE_EXT_FUNCTION(io_readb_mmu)
__DEFINE_EXT_FUNCTION(io_readw_mmu)
__DEFINE_EXT_FUNCTION(io_readl_mmu)
__DEFINE_EXT_FUNCTION(io_readq_mmu)
__DEFINE_EXT_FUNCTION(io_writeb_mmu)
__DEFINE_EXT_FUNCTION(io_writew_mmu)
__DEFINE_EXT_FUNCTION(io_writel_mmu)
__DEFINE_EXT_FUNCTION(io_writeq_mmu)
__DEFINE_EXT_FUNCTION(se_ensure_symbolic)
//__DEFINE_EXT_FUNCTION(s2e_on_tlb_miss)
__DEFINE_EXT_FUNCTION(s2e_on_page_fault)
__DEFINE_EXT_FUNCTION(s2e_is_port_symbolic)
__DEFINE_EXT_FUNCTION(s2e_is_mmio_symbolic)
__DEFINE_EXT_FUNCTION(se_is_mmio_symbolic_b)
__DEFINE_EXT_FUNCTION(se_is_mmio_symbolic_w)
__DEFINE_EXT_FUNCTION(se_is_mmio_symbolic_l)
__DEFINE_EXT_FUNCTION(se_is_mmio_symbolic_q)
__DEFINE_EXT_FUNCTION(se_is_vmem_symbolic)
__DEFINE_EXT_FUNCTION(s2e_on_privilege_change);
__DEFINE_EXT_FUNCTION(s2e_on_page_fault);
__DEFINE_EXT_FUNCTION(se_notdirty_mem_write)
__DEFINE_EXT_FUNCTION(se_notdirty_mem_read)
__DEFINE_EXT_FUNCTION(se_ismemfunc)
__DEFINE_EXT_FUNCTION(phys_get_ops)
__DEFINE_EXT_FUNCTION(is_notdirty_ops)
__DEFINE_EXT_FUNCTION(ldub_phys)
__DEFINE_EXT_FUNCTION(stb_phys)
__DEFINE_EXT_FUNCTION(lduw_phys)
__DEFINE_EXT_FUNCTION(stw_phys)
__DEFINE_EXT_FUNCTION(ldl_phys)
__DEFINE_EXT_FUNCTION(stl_phys)
__DEFINE_EXT_FUNCTION(ldq_phys)
__DEFINE_EXT_FUNCTION(stq_phys)
/* This catches obvious LLVM misconfigurations */
Module *M = m_llvmTranslator->getModule();
s2e->getDebugStream() << "Current data layout: " << M->getDataLayoutStr() << '\n';
s2e->getDebugStream() << "Current target triple: " << M->getTargetTriple() << '\n';
auto &td = M->getDataLayout();
if (td.getPointerSizeInBits() != 64) {
s2e->getWarningsStream() << "Something is broken in your LLVM build: LLVM thinks pointers are 32-bits!\n";
exit(-1);
}
setModule(m_llvmTranslator->getModule());
if (UseFastHelpers) {
disableConcreteLLVMHelpers();
}
/* Add dummy TB function declaration */
PointerType *tbFunctionArgTy = PointerType::get(IntegerType::get(ctx, 64), 0);
FunctionType *tbFunctionTy =
FunctionType::get(IntegerType::get(ctx, TCG_TARGET_REG_BITS),
ArrayRef<Type *>(vector<Type *>(1, PointerType::get(IntegerType::get(ctx, 64), 0))), false);
Function *tbFunction =
Function::Create(tbFunctionTy, Function::PrivateLinkage, "s2e_dummyTbFunction", m_llvmTranslator->getModule());
/* Create dummy main function containing just two instructions:
a call to TB function and ret */
Function *dummyMain = Function::Create(FunctionType::get(Type::getVoidTy(ctx), false), Function::ExternalLinkage,
"s2e_dummyMainFunction", m_llvmTranslator->getModule());
BasicBlock *dummyMainBB = BasicBlock::Create(ctx, "entry", dummyMain);
vector<Value *> tbFunctionArgs(1, ConstantPointerNull::get(tbFunctionArgTy));
CallInst::Create(tbFunction, ArrayRef<Value *>(tbFunctionArgs), "tbFunctionCall", dummyMainBB);
ReturnInst::Create(m_llvmTranslator->getContext(), dummyMainBB);
kmodule->updateModuleWithFunction(dummyMain);
m_dummyMain = kmodule->getKFunction(dummyMain);
#ifdef CONFIG_SYMBEX_MP
registerFunctionHandlers(*kmodule->getModule());
if (UseFastHelpers) {
replaceExternalFunctionsWithSpecialHandlers();
}
#endif
searcher = constructUserSearcher();
g_s2e_fork_on_symbolic_address = ForkOnSymbolicAddress;
g_s2e_concretize_io_addresses = ConcretizeIoAddress;
g_s2e_concretize_io_writes = ConcretizeIoWrites;
if (UseFastHelpers) {
if (!ForkOnSymbolicAddress) {
s2e->getWarningsStream() << UseFastHelpers.ArgStr << " can only be used if " << ForkOnSymbolicAddress.ArgStr
<< " is enabled\n";
exit(-1);
}
}
if (SinglePathMode) {
g_s2e_single_path_mode = 1;
s2e->getWarningsStream() << "S2E will run in single path mode. Forking and symbolic execution not allowed.\n";
}
if (OutputModule) {
if (auto os = s2e->openOutputFile("module.bc")) {
kmodule->outputModule(*os);
}
}
if (OutputSource) {
if (auto os = s2e->openOutputFile("assembly.ll")) {
kmodule->outputSource(*os, NoTruncateSourceLines);
}
}
}
void S2EExecutor::flushTb() {
tb_flush(env); // release references to TB functions
}
S2EExecutor::~S2EExecutor() {
}
S2EExecutionState *S2EExecutor::createInitialState() {
/* Create initial execution state */
S2EExecutionState *state = new S2EExecutionState(m_dummyMain);
auto factory = klee::DefaultSolverFactory::create(g_s2e->getOutputDirectory());
auto endSolver = factory->createEndSolver();
auto solver = factory->decorateSolver(endSolver);
state->setSolver(solver);
state->m_runningConcrete = true;
state->m_active = true;
state->setForking(EnableForking);
states.insert(state);
addedStates.insert(state);
updateStates(state);
#define __DEFINE_EXT_OBJECT_RO(name) \
{ \
predefinedSymbols.insert(std::make_pair(#name, (void *) &name)); \
auto op = state->addExternalObject((void *) &name, sizeof(name), true, true); \
op->setName(#name); \
}
#define __DEFINE_EXT_OBJECT_RO_SYMB(name) \
{ \
predefinedSymbols.insert(std::make_pair(#name, (void *) &name)); \
auto op = state->addExternalObject((void *) &name, sizeof(name), true, false); \
op->setName(#name); \
}
if (g_sqi.size != sizeof(g_sqi)) {
abort();
}
__DEFINE_EXT_OBJECT_RO(g_sqi)
__DEFINE_EXT_OBJECT_RO(env)
__DEFINE_EXT_OBJECT_RO(g_s2e)
__DEFINE_EXT_OBJECT_RO(g_s2e_state)
__DEFINE_EXT_OBJECT_RO(cpu_single_env)
__DEFINE_EXT_OBJECT_RO(loglevel)
__DEFINE_EXT_OBJECT_RO(logfile)
__DEFINE_EXT_OBJECT_RO_SYMB(parity_table)
__DEFINE_EXT_OBJECT_RO_SYMB(rclw_table)
__DEFINE_EXT_OBJECT_RO_SYMB(rclb_table)
m_s2e->getInfoStream(state) << "Created initial state" << '\n';
g_s2e_running_exception_emulation_code = (char *) &state->m_runningExceptionEmulationCode;
return state;
}
void S2EExecutor::initializeExecution(S2EExecutionState *state, bool executeAlwaysKlee) {
m_executeAlwaysKlee = executeAlwaysKlee;
initializeGlobals(*state);
kmodule->bindModuleConstants(globalAddresses);
initializeStateSwitchTimer();
}
void S2EExecutor::registerCpu(S2EExecutionState *initialState, CPUX86State *cpuEnv) {
std::cout << std::hex << "Adding CPU (addr = " << std::hex << cpuEnv << ", size = 0x" << sizeof(*cpuEnv) << ")"
<< std::dec << '\n';
if (sizeof(*cpuEnv) != cpuEnv->size) {
std::cerr << "Invalid cpu size structure\n";
abort();
}
/* Add registers and eflags area as a true symbolic area */
auto symbolicRegs = initialState->addExternalObject(cpuEnv, offsetof(CPUX86State, eip),
/* isReadOnly = */ false,
/* isSharedConcrete = */ false);
/* Add the rest of the structure as concrete-only area */
auto concreteRegs = initialState->addExternalObject(((uint8_t *) cpuEnv) + offsetof(CPUX86State, eip),
sizeof(CPUX86State) - offsetof(CPUX86State, eip),
/* isReadOnly = */ false,
/* isSharedConcrete = */ true);
initialState->m_registers.initialize(initialState->addressSpace, symbolicRegs, concreteRegs);
klee::ExecutionState::s_ignoredMergeObjects.insert(initialState->m_registers.getConcreteRegs());
}
void S2EExecutor::registerSharedExternalObject(S2EExecutionState *state, void *address, unsigned size) {
state->addExternalObject(address, size, false, true);
}
void S2EExecutor::registerRam(S2EExecutionState *initialState, MemoryDesc *region, uint64_t startAddress, uint64_t size,
uint64_t hostAddress, bool isSharedConcrete, bool saveOnContextSwitch, const char *name) {
#ifdef CONFIG_SYMBEX_MP
assert(isSharedConcrete || !saveOnContextSwitch);
assert(startAddress == (uint64_t) -1 || (startAddress & ~TARGET_PAGE_MASK) == 0);
assert((size & ~TARGET_PAGE_MASK) == 0);
assert((hostAddress & ~TARGET_PAGE_MASK) == 0);
m_s2e->getDebugStream() << "Adding memory block (startAddr = " << hexval(startAddress)
<< ", size = " << hexval(size) << ", hostAddr = " << hexval(hostAddress)
<< ", isSharedConcrete=" << isSharedConcrete << ", name=" << name << ")\n";
for (uint64_t addr = hostAddress; addr < hostAddress + size; addr += SE_RAM_OBJECT_SIZE) {
auto os = initialState->addExternalObject((void *) addr, SE_RAM_OBJECT_SIZE, false, isSharedConcrete);
os->setMemoryPage(true);
if (!isSharedConcrete) {
os->setSplittable(true);
os->setNotifyOnConcretenessChange(true);
}
#ifdef S2E_DEBUG_MEMOBJECT_NAME
std::stringstream ss;
ss << name << "_" << std::hex << (addr - hostAddress);
mo->setName(ss.str());
#endif
if (isSharedConcrete && (saveOnContextSwitch || !StateSharedMemory)) {
m_saveOnContextSwitch.push_back(os->getKey());
}
}
if (!isSharedConcrete) {
// mprotecting does not actually free the RAM, it's still committed,
// we need to explicitely unmap it.
// mprotect((void*) hostAddress, size, PROT_NONE);
if (munmap((void *) hostAddress, size) < 0) {
m_s2e->getWarningsStream(nullptr) << "Could not unmap host RAM\n";
exit(-1);
}
// Make sure that the memory space is reserved and won't be used anymore
// so that there are no conflicts with klee memory objects.
void *newhost = mmap((void *) hostAddress, size, PROT_NONE, MAP_ANONYMOUS | MAP_FIXED | MAP_PRIVATE, 0, 0);
if (newhost == MAP_FAILED || newhost != (void *) hostAddress) {
m_s2e->getWarningsStream(nullptr) << "Could not map host RAM\n";
exit(-1);
}
}
initialState->m_asCache.registerPool(hostAddress, size);
#endif
}
void S2EExecutor::registerDirtyMask(S2EExecutionState *state, uint64_t hostAddress, uint64_t size) {
// Assume that dirty mask is small enough, so no need to split it in small pages
auto dirtyMask = state->addExternalObject((void *) hostAddress, size, false, true);
state->m_memory.initialize(&state->addressSpace, &state->m_asCache, &state->m_active, state, state, dirtyMask);
klee::ExecutionState::s_ignoredMergeObjects.insert(state->m_memory.getDirtyMask());
g_se_dirty_mask_addend = state->mem()->getDirtyMaskStoreAddend();
}
void S2EExecutor::splitStates(const std::vector<S2EExecutionState *> &allStates, StateSet &parentSet,
StateSet &childSet) {
unsigned size = allStates.size();
unsigned n = size / 2;
for (unsigned i = 0; i < n; ++i) {
parentSet.insert(allStates[i]);
}
for (unsigned i = n; i < allStates.size(); ++i) {
childSet.insert(allStates[i]);
}
}
void S2EExecutor::computeNewStateGuids(std::unordered_map<ExecutionState *, uint64_t> &newIds, StateSet &parentSet,
StateSet &childSet) {
StateSet commonStates;
// If we there are states that appear in both sets, we must
// reassign a guid to them.
std::set_intersection(parentSet.begin(), parentSet.end(), childSet.begin(), childSet.end(),
std::inserter(commonStates, commonStates.begin()));
for (auto state : commonStates) {
// TODO: if fork fails, we'll end up with unused state ids...
// It doesn't matter in practice, but may be unintuitive
// (i.e., why do I have missing state ids in my trace?)
// Reverting this increment is hard unfortunately.
newIds[state] = g_s2e->fetchAndIncrementStateId();
}
}
void S2EExecutor::doLoadBalancing() {
if (states.size() < 2) {
return;
}
// Don't bother copying stuff if it's obvious that it'll very likely fail
if (m_s2e->getCurrentInstanceCount() == m_s2e->getMaxInstances()) {
return;
}
std::vector<S2EExecutionState *> allStates;
foreach2 (it, states.begin(), states.end()) {
S2EExecutionState *s2estate = static_cast<S2EExecutionState *>(*it);
if (!s2estate->isZombie() && !s2estate->isPinned()) {
allStates.push_back(s2estate);
}
}
if (allStates.size() < 2) {
return;
}
g_s2e->getDebugStream() << "LoadBalancing: starting\n";
bool proceed = true;
m_s2e->getCorePlugin()->onProcessForkDecide.emit(&proceed);
if (!proceed) {
g_s2e->getDebugStream() << "LoadBalancing: a plugin stopped load balancing\n";
return;
}
// These two sets are the two partitions.
StateSet parentSet, childSet;
// Do the splitting before the fork, because we want to
// let plugins modify the partition. Some plugins might
// even want to keep a state in all instances.
splitStates(allStates, parentSet, childSet);
m_s2e->getCorePlugin()->onStatesSplit.emit(parentSet, childSet);
std::unordered_map<ExecutionState *, uint64_t> newIds;
computeNewStateGuids(newIds, parentSet, childSet);
m_inLoadBalancing = true;
unsigned parentId = m_s2e->getCurrentInstanceId();
m_s2e->getCorePlugin()->onProcessFork.emit(true, false, -1);
int child = m_s2e->fork();
if (child < 0) {
// Fork did not succeed
m_s2e->getCorePlugin()->onProcessFork.emit(false, false, -1);
m_inLoadBalancing = false;
return;
}
m_s2e->getCorePlugin()->onProcessFork.emit(false, child, parentId);
g_s2e->getDebugStream() << "LoadBalancing: terminating states\n";
/// Go through all the states and kill those that are
/// not in the sets.
StateSet ¤tSet = child ? childSet : parentSet;
for (auto state : allStates) {
S2EExecutionState *s2estate = static_cast<S2EExecutionState *>(state);
if (!currentSet.count(s2estate)) {
Executor::terminateState(*s2estate);
// This is important if we kill the current state
s2estate->zombify();
}
}
// We have to re-assign globally unique IDs to states that
// have been kept in both child and parent sets. This is required
// to avoid confusing execution tracers.
for (auto &state : newIds) {
S2EExecutionState *s2estate = static_cast<S2EExecutionState *>(state.first);
if (child) {
g_s2e->getDebugStream(s2estate) << "Assigning new guid " << state.second << "\n";
s2estate->assignGuid(state.second);
} else {
g_s2e->getDebugStream(s2estate) << "Notifying guid assignment " << state.second << "\n";
m_s2e->getCorePlugin()->onStateGuidAssignment.emit(s2estate, state.second);
}
}
m_s2e->getCorePlugin()->onProcessForkComplete.emit(child);
m_inLoadBalancing = false;
}
void S2EExecutor::stateSwitchTimerCallback(void *opaque) {
S2EExecutor *c = (S2EExecutor *) opaque;
assert(env->current_tb == nullptr);
if (g_s2e_state) {
c->doLoadBalancing();
S2EExecutionState *nextState = c->selectNextState(g_s2e_state);
if (nextState) {
g_s2e_state = nextState;
} else {
// Do not reschedule the timer anymore
return;
}
}
libcpu_mod_timer(c->m_stateSwitchTimer, libcpu_get_clock_ms(host_clock) + 100);
}
void S2EExecutor::initializeStateSwitchTimer() {
m_stateSwitchTimer = libcpu_new_timer_ms(host_clock, &stateSwitchTimerCallback, this);
libcpu_mod_timer(m_stateSwitchTimer, libcpu_get_clock_ms(host_clock) + 100);
}
void S2EExecutor::resetStateSwitchTimer() {
libcpu_mod_timer(m_stateSwitchTimer, libcpu_get_clock_ms(host_clock));
}
void S2EExecutor::doStateSwitch(S2EExecutionState *oldState, S2EExecutionState *newState) {
assert(oldState || newState);
assert(!oldState || oldState->m_active);
assert(!newState || !newState->m_active);
assert(!newState || !newState->isRunningConcrete());
// Some state save/restore logic flushes the cache.
// This can have bad effects in case of saving/restoring states
// that were in the middle of a memory operation. Therefore,
// we disable it here and re-enable after the new state has been activated.
g_se_disable_tlb_flush = 1;
// Clear the asynchronous request queue, which is not part of the KVM state
s2e_kvm_flush_disk();
cpu_disable_ticks();
m_s2e->getInfoStream(oldState) << "Switching from state " << (oldState ? oldState->getID() : -1) << " to state "
<< (newState ? newState->getID() : -1) << '\n';
uint64_t totalCopied = 0;
uint64_t objectsCopied = 0;
if (oldState) {
if (VerboseStateSwitching) {
m_s2e->getDebugStream(oldState) << "Saving state\n";
}
if (oldState->isRunningConcrete()) {
oldState->switchToSymbolic();
}
for (auto &mo : m_saveOnContextSwitch) {
auto oldOS = oldState->addressSpace.findObject(mo.address);
auto oldWOS = oldState->addressSpace.getWriteable(oldOS);
uint8_t *oldStore = oldWOS->getConcreteBuffer();
assert(oldStore);
memcpy(oldStore, (uint8_t *) mo.address, mo.size);
}
// XXX: specify which state should be used
s2e_kvm_save_device_state();
*oldState->m_timersState = timers_state;
oldState->m_registers.saveConcreteState();
oldState->m_active = false;
}
if (newState) {
if (VerboseStateSwitching) {
m_s2e->getDebugStream(newState) << "Restoring state\n";
}
timers_state = *newState->m_timersState;
if (g_sqi.exec.clock_scaling_factor) {
*g_sqi.exec.clock_scaling_factor = timers_state.cpu_clock_scale_factor;
}
jmp_buf jmp_env;
memcpy(&jmp_env, &env->jmp_env, sizeof(jmp_buf));
newState->m_registers.restoreConcreteState();
memcpy(&env->jmp_env, &jmp_env, sizeof(jmp_buf));
newState->m_active = true;
// Devices may need to write to memory, which can be done
// after the state is activated
// XXX: assigning g_s2e_state here is ugly but is required for restoreDeviceState...
g_s2e_state = newState;
g_se_dirty_mask_addend = g_s2e_state->mem()->getDirtyMaskStoreAddend();
// XXX: specify which state should be used
s2e_kvm_restore_device_state();
for (auto &mo : m_saveOnContextSwitch) {
auto newOS = newState->addressSpace.findObject(mo.address);
const uint8_t *newStore = newOS->getConcreteBuffer();
assert(newStore);
memcpy((uint8_t *) mo.address, newStore, mo.size);
totalCopied += mo.size;
objectsCopied++;
}
}
cpu_enable_ticks();
if (VerboseStateSwitching) {
s2e_debug_print("Copied %d (count=%d)\n", totalCopied, objectsCopied);
}
if (FlushTBsOnStateSwitch) {
se_tb_safe_flush();
}
assert(env->current_tb == nullptr);
g_se_disable_tlb_flush = 0;
// m_s2e->getCorePlugin()->onStateSwitch.emit(oldState, newState);
}
ExecutionState *S2EExecutor::selectSearcherState(S2EExecutionState *state) {
ExecutionState *newState = nullptr;
if (!searcher->empty()) {
newState = &searcher->selectState();
}
if (!newState) {
m_s2e->getWarningsStream() << "All states were terminated" << '\n';
foreach2 (it, m_deletedStates.begin(), m_deletedStates.end()) {
S2EExecutionState *s = *it;
// Leave the current state in a zombie form to let the process exit gracefully.
if (s != g_s2e_state) {
delete s;
}
}
m_deletedStates.clear();
g_s2e->getCorePlugin()->onEngineShutdown.emit();
// Flush here just in case ~S2E() is not called (e.g., if atexit()
// shutdown handler was not called properly).
g_s2e->flushOutputStreams();
exit(0);
}
return newState;
}
S2EExecutionState *S2EExecutor::selectNextState(S2EExecutionState *state) {
assert(state->m_active);
updateStates(state);
/* Prevent state switching */
if (state->isStateSwitchForbidden() && !state->isZombie()) {
return state;
}
ExecutionState *nstate = selectSearcherState(state);
if (nstate == nullptr) {
return nullptr;
}
// This assertion must go before the cast to S2EExecutionState.
// In case the searcher returns a bogus state, this allows
// spotting it immediately. The dynamic cast however, might cause
// memory corruptions.
assert(states.find(nstate) != states.end());
S2EExecutionState *newState = dynamic_cast<S2EExecutionState *>(nstate);
assert(newState);
assert(!newState->isZombie());
newState->setYieldState(false);
if (!state->m_active) {
/* Current state might be switched off by merge method */
state = nullptr;
}
if (newState != state) {
doStateSwitch(state, newState);
g_s2e->getCorePlugin()->onStateSwitch.emit(state, newState);
}
// We can't free the state immediately if it is the current state.
// Do it now.
foreach2 (it, m_deletedStates.begin(), m_deletedStates.end()) {
S2EExecutionState *s = *it;
assert(s != newState);
delete s;
}
m_deletedStates.clear();
updateConcreteFastPath(newState);
return newState;
}
/** Simulate start of function execution, creating KLEE structs of required */
void S2EExecutor::prepareFunctionExecution(S2EExecutionState *state, llvm::Function *function,
const std::vector<klee::ref<klee::Expr>> &args) {
auto kf = kmodule->bindFunctionConstants(globalAddresses, function);
/* Emulate call to a TB function */
state->prevPC = state->pc;
state->pushFrame(state->pc, kf);
state->pc = kf->getInstructions();
/* Pass argument */
for (unsigned i = 0; i < args.size(); ++i) {
state->bindArgument(kf, i, args[i]);
}
}
inline bool S2EExecutor::executeInstructions(S2EExecutionState *state, unsigned callerStackSize) {
try {
while (state->stack.size() != callerStackSize) {
assert(!g_s2e_fast_concrete_invocation);
KInstruction *ki = state->pc;
if (PrintLLVMInstructions) {
m_s2e->getDebugStream(state)
<< "executing " << ki->inst->getParent()->getParent()->getName().str() << ": " << *ki->inst << '\n';
}
state->stepInstruction();
executeInstruction(*state, ki);
updateStates(state);
// Handle the case where we killed the current state inside processFork