From c09306ffd894f95be195723327d5b17dca73ebd1 Mon Sep 17 00:00:00 2001 From: Felix Rath Date: Fri, 22 May 2020 14:09:10 +0200 Subject: Implemented support for C++ Exceptions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We implement the Itanium ABI unwinding base-API, and leave the C++-specific parts to libcxxabi. Co-authored-by: Lukas Wölfer --- runtime/CMakeLists.txt | 14 ++ runtime/Makefile.cmake.bitcode | 4 + runtime/Makefile.cmake.bitcode.config.in | 5 + runtime/klee-eh-cxx/Makefile.cmake.bitcode | 13 ++ runtime/klee-eh-cxx/klee_eh_cxx.cpp | 218 +++++++++++++++++++++++++++++ 5 files changed, 254 insertions(+) create mode 100644 runtime/klee-eh-cxx/Makefile.cmake.bitcode create mode 100644 runtime/klee-eh-cxx/klee_eh_cxx.cpp (limited to 'runtime') diff --git a/runtime/CMakeLists.txt b/runtime/CMakeLists.txt index e3619f3d..8e7e7226 100644 --- a/runtime/CMakeLists.txt +++ b/runtime/CMakeLists.txt @@ -32,6 +32,12 @@ else() set(BUILD_POSIX_RUNTIME 0) endif() +if (ENABLE_KLEE_LIBCXX) + set(BUILD_KLEE_EH_CXX 1) +else() + set(BUILD_KLEE_EH_CXX 0) +endif() + # Configure the bitcode build system configure_file("Makefile.cmake.bitcode.config.in" "Makefile.cmake.bitcode.config" @@ -48,6 +54,9 @@ set(BITCODE_LIBRARIES "Intrinsic" "klee-libc" "FreeStanding") if (ENABLE_POSIX_RUNTIME) list(APPEND BITCODE_LIBRARIES "POSIX") endif() +if (ENABLE_KLEE_LIBCXX) + list(APPEND BITCODE_LIBRARIES "klee-eh-cxx") +endif() foreach (bl ${BITCODE_LIBRARIES}) configure_file("${bl}/Makefile.cmake.bitcode" "${CMAKE_CURRENT_BINARY_DIR}/${bl}/Makefile.cmake.bitcode" @@ -136,6 +145,11 @@ if (ENABLE_POSIX_RUNTIME) "${KLEE_RUNTIME_DIRECTORY}/libkleeRuntimePOSIX.bca") endif() +if (ENABLE_KLEE_LIBCXX) + list(APPEND RUNTIME_FILES_TO_INSTALL + "${KLEE_RUNTIME_DIRECTORY}/libklee-eh-cxx.bca") +endif() + install(FILES ${RUNTIME_FILES_TO_INSTALL} DESTINATION "${KLEE_INSTALL_RUNTIME_DIR}") diff --git a/runtime/Makefile.cmake.bitcode b/runtime/Makefile.cmake.bitcode index 03da435e..1dfdfde6 100644 --- a/runtime/Makefile.cmake.bitcode +++ b/runtime/Makefile.cmake.bitcode @@ -17,4 +17,8 @@ ifneq ($(ENABLE_POSIX_RUNTIME),0) DIRS += POSIX endif +ifneq ($(BUILD_KLEE_EH_CXX),0) + DIRS += klee-eh-cxx +endif + include $(LEVEL)/Makefile.cmake.bitcode.rules diff --git a/runtime/Makefile.cmake.bitcode.config.in b/runtime/Makefile.cmake.bitcode.config.in index 5916d79a..4e2354b8 100644 --- a/runtime/Makefile.cmake.bitcode.config.in +++ b/runtime/Makefile.cmake.bitcode.config.in @@ -11,6 +11,7 @@ # #===------------------------------------------------------------------------===# LLVMCC := @LLVMCC@ +LLVMCXX := @LLVMCXX@ LLVM_LINK := @LLVM_LINK@ LLVM_AR := @LLVM_AR@ LLVM_VERSION_MAJOR := @LLVM_VERSION_MAJOR@ @@ -31,6 +32,10 @@ RUNTIME_CONFIG_STRING := @KLEE_RUNTIME_BUILD_TYPE@ # Optional features ENABLE_POSIX_RUNTIME := @BUILD_POSIX_RUNTIME@ +BUILD_KLEE_CXXABI := @BUILD_KLEE_CXXABI@ +KLEE_LIBCXX_INCLUDE_DIR := @KLEE_LIBCXX_INCLUDE_DIR@ +KLEE_LIBCXXABI_DIR := @KLEE_LIBCXXABI_DIR@ +KLEE_INCLUDE_DIR := @CMAKE_SOURCE_DIR@/include # Commands MKDIR := mkdir diff --git a/runtime/klee-eh-cxx/Makefile.cmake.bitcode b/runtime/klee-eh-cxx/Makefile.cmake.bitcode new file mode 100644 index 00000000..f29b947d --- /dev/null +++ b/runtime/klee-eh-cxx/Makefile.cmake.bitcode @@ -0,0 +1,13 @@ +include ../Makefile.cmake.bitcode.config + +SRC_DIR=$(ROOT_SRC)/klee-eh-cxx + +ARCHIVE_FILE=$(ARCHIVE_DEST)/libklee-eh-cxx.bca + +all: $(ARCHIVE_FILE) + +klee_eh_cxx.bc: $(SRC_DIR)/klee_eh_cxx.cpp + $(LLVMCXX) -nostdinc++ -emit-llvm -c -I$(KLEE_INCLUDE_DIR) -I $(KLEE_LIBCXXABI_DIR)/include -I $(KLEE_LIBCXXABI_DIR)/src -I $(KLEE_LIBCXX_INCLUDE_DIR) $(SRC_DIR)/klee_eh_cxx.cpp -o $@ + +$(ARCHIVE_FILE): klee_eh_cxx.bc + $(LLVM_AR) rcs $@ $< diff --git a/runtime/klee-eh-cxx/klee_eh_cxx.cpp b/runtime/klee-eh-cxx/klee_eh_cxx.cpp new file mode 100644 index 00000000..8eafac2c --- /dev/null +++ b/runtime/klee-eh-cxx/klee_eh_cxx.cpp @@ -0,0 +1,218 @@ +#include +#include +#include +#include +#include + +#include + +#include + +// from libcxxabi +#include +#include + +// implemented in the SpecialFunctionHandler +extern "C" std::uint32_t klee_eh_typeid_for(const void *); + +// we use some internals of libcxxabi, so we make our life easier here +using __shim_type_info = __cxxabiv1::__shim_type_info; +using __cxa_exception = __cxxabiv1::__cxa_exception; + +namespace { +// Used to determine whether a catch-clause can catch an exception +bool _klee_eh_can_catch(const void *catcherType, + const __shim_type_info *exceptionType, + void *&adjustedPtr) { + return static_cast(catcherType) + ->can_catch(exceptionType, adjustedPtr); +} + +// Some utility functions to convert between the different exception +// representations. These are mostly copied from libcxxabi, except +// for small adjustments so they work in our code as well. + +// Copied from libcxxabi/cxa_exception.cpp (including comments) +inline +__cxa_exception* +cxa_exception_from_thrown_object(void* thrown_object) +{ + return static_cast<__cxa_exception*>(thrown_object) - 1; +} + +// Copied from libcxxabi/cxa_exception.cpp (including comments) +// +// Get the exception object from the unwind pointer. +// Relies on the structure layout, where the unwind pointer is right in +// front of the user's exception object +inline +__cxa_exception* +cxa_exception_from_exception_unwind_exception(_Unwind_Exception* unwind_exception) +{ + return cxa_exception_from_thrown_object(unwind_exception + 1); +} + +// Copied from libcxxabi/cxa_personality.cpp (including comments) +void* +get_thrown_object_ptr(_Unwind_Exception* unwind_exception) +{ + // added for usage inside KLEE (i.e., outside of libcxxabi) + using namespace __cxxabiv1; + + // Even for foreign exceptions, the exception object is *probably* at unwind_exception + 1 + // Regardless, this library is prohibited from touching a foreign exception + void* adjustedPtr = unwind_exception + 1; + if (__getExceptionClass(unwind_exception) == kOurDependentExceptionClass) + adjustedPtr = ((__cxa_dependent_exception*)adjustedPtr - 1)->primaryException; + return adjustedPtr; +} +} // namespace + +// Our implementation of a personality function for handling +// libcxxabi-exceptions. Follows how libcxxabi's __gxx_personality_v0 handles +// exceptions. +[[gnu::used]] extern "C" std::int32_t +_klee_eh_cxx_personality(_Unwind_Exception *exceptionPointer, + const std::size_t num_bytes, + const unsigned char *lp_clauses) { + assert(__cxxabiv1::__isOurExceptionClass(exceptionPointer) && + "unexpected exception class found"); + + __cxa_exception *exception = + cxa_exception_from_exception_unwind_exception(exceptionPointer); + const __shim_type_info *exceptionType = + static_cast(exception->exceptionType); + void *const exceptionObjectPtr = get_thrown_object_ptr(exceptionPointer); + + const unsigned char *cur_pos = lp_clauses; + const unsigned char *lp_clauses_end = lp_clauses + num_bytes; + + while (cur_pos < lp_clauses_end) { + const unsigned char type = *cur_pos; + cur_pos += 1; + if (type == 0) { // catch-clause + const void *catcherType = *reinterpret_cast(cur_pos); + cur_pos += sizeof(const void *); + if (catcherType == NULL) { + // catch-all clause + exception->adjustedPtr = exceptionObjectPtr; + return klee_eh_typeid_for(catcherType); + } + void *adjustedPtr = exceptionObjectPtr; + if (_klee_eh_can_catch(catcherType, exceptionType, adjustedPtr)) { + exception->adjustedPtr = adjustedPtr; + return klee_eh_typeid_for(catcherType); + } + } else { // filter-clause + unsigned char num_filters = type - 1; + while (num_filters > 0) { + const void *catcher = *reinterpret_cast(cur_pos); + cur_pos += sizeof(const void *); + if (catcher == NULL) { + // catch-all filter clause, should always be entered + exception->adjustedPtr = exceptionObjectPtr; + return -1; + } + void *adjustedPtr = exceptionObjectPtr; + if (_klee_eh_can_catch(catcher, exceptionType, adjustedPtr)) { + exception->adjustedPtr = adjustedPtr; + break; + } + num_filters -= 1; + } + if (num_filters == 0) { + // exception was not one of the given ones -> filter it out + return -1; + } + } + } + + // no handling clause found + return 0; +} + +// Implemented in the SpecialFunctionHandler +extern "C" void _klee_eh_Unwind_RaiseException_impl(void *); + +// Provide an implementation of the Itanium unwinding base-API +// (https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html#base-abi) +// These functions will be called by language-specific exception handling +// implementations, such as libcxxabi. +extern "C" { +// The main entry point for stack unwinding. This function performs the 2-phase +// unwinding process, calling the personality function as required. We implement +// this mostly inside KLEE as it requires direct manipulation of the state's +// stack. +_Unwind_Reason_Code +_Unwind_RaiseException(struct _Unwind_Exception *exception_object) { + // this will either unwind the stack if a handler is found, or return if not + _klee_eh_Unwind_RaiseException_impl(exception_object); + + // if we couldn't find a handler, return an error + return _URC_END_OF_STACK; +} + +// According to the Itanium ABI: +// "Deletes the given exception object. If a given runtime resumes normal +// execution after catching a foreign exception, it will not know how to delete +// that exception. Such an exception will be deleted by calling +// _Unwind_DeleteException. This is a convenience function that calls the +// function pointed to by the exception_cleanup field of the exception header." +void _Unwind_DeleteException(struct _Unwind_Exception *exception_object) { + // Implemented in the same way as LLVM's libunwind version + if (exception_object->exception_cleanup != NULL) + exception_object->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, + exception_object); +} + +// At the LLVM IR level we will encounter the `resume`-Instruction instead of +// calls to this function. LLVM lowers `resume` to a call to `_Unwind_Resume` +// during later compilation stages. +void _Unwind_Resume(struct _Unwind_Exception *exception_object) { + klee_report_error(__FILE__, __LINE__, "_Unwind_Resume should not appear", + "unexpected.err"); +} + +// The rest of these assume a binary execution environment and thus aren't +// supported. While ForcedUnwind could be called by users, it is never actually +// called inside of libcxxabi. The others are usually called by the personality +// function, but we implement that ourselves. +_Unwind_Reason_Code +_Unwind_ForcedUnwind(struct _Unwind_Exception *exception_object, + _Unwind_Stop_Fn stop, void *stop_parameter) { + klee_report_error(__FILE__, __LINE__, "_Unwind_ForcedUnwind not supported", + "unsupported.err"); +} + +_Unwind_Word _Unwind_GetGR(struct _Unwind_Context *context, int index) { + klee_report_error(__FILE__, __LINE__, "_Unwind_GetGR not supported", + "unsupported.err"); +} + +void _Unwind_SetGR(struct _Unwind_Context *context, int index, + _Unwind_Word new_value) { + klee_report_error(__FILE__, __LINE__, "_Unwind_SetGR not supported", + "unsupported.err"); +} + +_Unwind_Word _Unwind_GetIP(struct _Unwind_Context *context) { + klee_report_error(__FILE__, __LINE__, "_Unwind_GetIP not supported", + "unsupported.err"); +} + +void _Unwind_SetIP(struct _Unwind_Context *context, _Unwind_Word new_value) { + klee_report_error(__FILE__, __LINE__, "_Unwind_SetIP not unsupported", + "unsupported.err"); +} + +void *_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) { + klee_report_error(__FILE__, __LINE__, + "_Unwind_GetLanguageSpecificData not supported", + "unsupported.err"); +} + +_Unwind_Ptr _Unwind_GetRegionStart(struct _Unwind_Context *context) { + klee_report_error(__FILE__, __LINE__, "_Unwind_GetRegionStart not supported", + "unsupported.err"); +} +} \ No newline at end of file -- cgit 1.4.1