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Diffstat (limited to 'src/Unwind-seh.cpp')
| -rw-r--r-- | src/Unwind-seh.cpp | 468 |
1 files changed, 468 insertions, 0 deletions
diff --git a/src/Unwind-seh.cpp b/src/Unwind-seh.cpp new file mode 100644 index 0000000..aaf2e98 --- /dev/null +++ b/src/Unwind-seh.cpp @@ -0,0 +1,468 @@ +//===--------------------------- Unwind-seh.cpp ---------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Implements SEH-based Itanium C++ exceptions. +// +//===----------------------------------------------------------------------===// + +#include "config.h" + +#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) + +#include <unwind.h> + +#include <stdint.h> +#include <stdbool.h> +#include <stdlib.h> + +#include <windef.h> +#include <excpt.h> +#include <winnt.h> +#include <ntstatus.h> + +#include "libunwind_ext.h" +#include "UnwindCursor.hpp" + +using namespace libunwind; + +#define STATUS_USER_DEFINED (1u << 29) + +#define STATUS_GCC_MAGIC (('G' << 16) | ('C' << 8) | 'C') + +#define MAKE_CUSTOM_STATUS(s, c) \ + ((NTSTATUS)(((s) << 30) | STATUS_USER_DEFINED | (c))) +#define MAKE_GCC_EXCEPTION(c) \ + MAKE_CUSTOM_STATUS(STATUS_SEVERITY_SUCCESS, STATUS_GCC_MAGIC | ((c) << 24)) + +/// SEH exception raised by libunwind when the program calls +/// \c _Unwind_RaiseException. +#define STATUS_GCC_THROW MAKE_GCC_EXCEPTION(0) // 0x20474343 +/// SEH exception raised by libunwind to initiate phase 2 of exception +/// handling. +#define STATUS_GCC_UNWIND MAKE_GCC_EXCEPTION(1) // 0x21474343 + +/// Class of foreign exceptions based on unrecognized SEH exceptions. +static const uint64_t kSEHExceptionClass = 0x434C4E4753454800; // CLNGSEH\0 + +/// Exception cleanup routine used by \c _GCC_specific_handler to +/// free foreign exceptions. +static void seh_exc_cleanup(_Unwind_Reason_Code urc, _Unwind_Exception *exc) { + if (exc->exception_class != kSEHExceptionClass) + _LIBUNWIND_ABORT("SEH cleanup called on non-SEH exception"); + free(exc); +} + +static int _unw_init_seh(unw_cursor_t *cursor, CONTEXT *ctx); +static DISPATCHER_CONTEXT *_unw_seh_get_disp_ctx(unw_cursor_t *cursor); +static void _unw_seh_set_disp_ctx(unw_cursor_t *cursor, DISPATCHER_CONTEXT *disp); + +/// Common implementation of SEH-style handler functions used by Itanium- +/// style frames. Depending on how and why it was called, it may do one of: +/// a) Delegate to the given Itanium-style personality function; or +/// b) Initiate a collided unwind to halt unwinding. +_LIBUNWIND_EXPORT EXCEPTION_DISPOSITION +_GCC_specific_handler(PEXCEPTION_RECORD ms_exc, PVOID frame, PCONTEXT ms_ctx, + DISPATCHER_CONTEXT *disp, __personality_routine pers) { + unw_context_t uc; + unw_cursor_t cursor; + _Unwind_Exception *exc; + _Unwind_Action action; + struct _Unwind_Context *ctx = nullptr; + _Unwind_Reason_Code urc; + uintptr_t retval, target; + bool ours = false; + + _LIBUNWIND_TRACE_UNWINDING("_GCC_specific_handler(%#010x(%x), %p)", ms_exc->ExceptionCode, ms_exc->ExceptionFlags, frame); + if (ms_exc->ExceptionCode == STATUS_GCC_UNWIND) { + if (IS_TARGET_UNWIND(ms_exc->ExceptionFlags)) { + // Set up the upper return value (the lower one and the target PC + // were set in the call to RtlUnwindEx()) for the landing pad. +#ifdef __x86_64__ + disp->ContextRecord->Rdx = ms_exc->ExceptionInformation[3]; +#elif defined(__arm__) + disp->ContextRecord->R1 = ms_exc->ExceptionInformation[3]; +#endif + } + // This is the collided unwind to the landing pad. Nothing to do. + return ExceptionContinueSearch; + } + + if (ms_exc->ExceptionCode == STATUS_GCC_THROW) { + // This is (probably) a libunwind-controlled exception/unwind. Recover the + // parameters which we set below, and pass them to the personality function. + ours = true; + exc = (_Unwind_Exception *)ms_exc->ExceptionInformation[0]; + if (!IS_UNWINDING(ms_exc->ExceptionFlags) && ms_exc->NumberParameters > 1) { + ctx = (struct _Unwind_Context *)ms_exc->ExceptionInformation[1]; + action = (_Unwind_Action)ms_exc->ExceptionInformation[2]; + } + } else { + // Foreign exception. + exc = (_Unwind_Exception *)malloc(sizeof(_Unwind_Exception)); + exc->exception_class = kSEHExceptionClass; + exc->exception_cleanup = seh_exc_cleanup; + memset(exc->private_, 0, sizeof(exc->private_)); + } + if (!ctx) { + _unw_init_seh(&cursor, disp->ContextRecord); + _unw_seh_set_disp_ctx(&cursor, disp); + unw_set_reg(&cursor, UNW_REG_IP, disp->ControlPc-1); + ctx = (struct _Unwind_Context *)&cursor; + + if (!IS_UNWINDING(ms_exc->ExceptionFlags)) { + if (ours && ms_exc->NumberParameters > 1) + action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_FORCE_UNWIND); + else + action = _UA_SEARCH_PHASE; + } else { + if (ours && ms_exc->ExceptionInformation[1] == (ULONG_PTR)frame) + action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME); + else + action = _UA_CLEANUP_PHASE; + } + } + + _LIBUNWIND_TRACE_UNWINDING("_GCC_specific_handler() calling personality function %p(1, %d, %llx, %p, %p)", pers, action, exc->exception_class, exc, ctx); + urc = pers(1, action, exc->exception_class, exc, ctx); + _LIBUNWIND_TRACE_UNWINDING("_GCC_specific_handler() personality returned %d", urc); + switch (urc) { + case _URC_CONTINUE_UNWIND: + // If we're in phase 2, and the personality routine said to continue + // at the target frame, we're in real trouble. + if (action & _UA_HANDLER_FRAME) + _LIBUNWIND_ABORT("Personality continued unwind at the target frame!"); + return ExceptionContinueSearch; + case _URC_HANDLER_FOUND: + // If we were called by __libunwind_seh_personality(), indicate that + // a handler was found; otherwise, initiate phase 2 by unwinding. + if (ours && ms_exc->NumberParameters > 1) + return 4 /* ExecptionExecuteHandler in mingw */; + // This should never happen in phase 2. + if (IS_UNWINDING(ms_exc->ExceptionFlags)) + _LIBUNWIND_ABORT("Personality indicated exception handler in phase 2!"); + exc->private_[1] = (ULONG_PTR)frame; + if (ours) { + ms_exc->NumberParameters = 4; + ms_exc->ExceptionInformation[1] = (ULONG_PTR)frame; + } + // FIXME: Indicate target frame in foreign case! + // phase 2: the clean up phase + RtlUnwindEx(frame, (PVOID)disp->ControlPc, ms_exc, exc, ms_ctx, disp->HistoryTable); + _LIBUNWIND_ABORT("RtlUnwindEx() failed"); + case _URC_INSTALL_CONTEXT: { + // If we were called by __libunwind_seh_personality(), indicate that + // a handler was found; otherwise, it's time to initiate a collided + // unwind to the target. + if (ours && !IS_UNWINDING(ms_exc->ExceptionFlags) && ms_exc->NumberParameters > 1) + return 4 /* ExecptionExecuteHandler in mingw */; + // This should never happen in phase 1. + if (!IS_UNWINDING(ms_exc->ExceptionFlags)) + _LIBUNWIND_ABORT("Personality installed context during phase 1!"); + exc->private_[2] = disp->TargetIp; +#ifdef __x86_64__ + unw_get_reg(&cursor, UNW_X86_64_RAX, &retval); + unw_get_reg(&cursor, UNW_X86_64_RDX, &exc->private_[3]); +#elif defined(__arm__) + unw_get_reg(&cursor, UNW_ARM_R0, &retval); + unw_get_reg(&cursor, UNW_ARM_R1, &exc->private_[3]); +#endif + unw_get_reg(&cursor, UNW_REG_IP, &target); + ms_exc->ExceptionCode = STATUS_GCC_UNWIND; + ms_exc->ExceptionInformation[2] = disp->TargetIp; + ms_exc->ExceptionInformation[3] = exc->private_[3]; + // Give NTRTL some scratch space to keep track of the collided unwind. + // Don't use the one that was passed in; we don't want to overwrite the + // context in the DISPATCHER_CONTEXT. + CONTEXT new_ctx; + RtlUnwindEx(frame, (PVOID)target, ms_exc, (PVOID)retval, &new_ctx, disp->HistoryTable); + _LIBUNWIND_ABORT("RtlUnwindEx() failed"); + } + // Anything else indicates a serious problem. + default: return ExceptionContinueExecution; + } +} + +/// Personality function returned by \c unw_get_proc_info() in SEH contexts. +/// This is a wrapper that calls the real SEH handler function, which in +/// turn (at least, for Itanium-style frames) calls the real Itanium +/// personality function (see \c _GCC_specific_handler()). +extern "C" _Unwind_Reason_Code +__libunwind_seh_personality(int version, _Unwind_Action state, + uint64_t klass, _Unwind_Exception *exc, + struct _Unwind_Context *context) { + EXCEPTION_RECORD ms_exc; + bool phase2 = (state & (_UA_SEARCH_PHASE|_UA_CLEANUP_PHASE)) == _UA_CLEANUP_PHASE; + ms_exc.ExceptionCode = STATUS_GCC_THROW; + ms_exc.ExceptionFlags = 0; + ms_exc.NumberParameters = 3; + ms_exc.ExceptionInformation[0] = (ULONG_PTR)exc; + ms_exc.ExceptionInformation[1] = (ULONG_PTR)context; + ms_exc.ExceptionInformation[2] = state; + DISPATCHER_CONTEXT *disp_ctx = _unw_seh_get_disp_ctx((unw_cursor_t *)context); + EXCEPTION_DISPOSITION ms_act = disp_ctx->LanguageHandler(&ms_exc, + (PVOID)disp_ctx->EstablisherFrame, + disp_ctx->ContextRecord, + disp_ctx); + switch (ms_act) { + case ExceptionContinueSearch: return _URC_CONTINUE_UNWIND; + case 4 /*ExceptionExecuteHandler*/: + return phase2 ? _URC_INSTALL_CONTEXT : _URC_HANDLER_FOUND; + default: + return phase2 ? _URC_FATAL_PHASE2_ERROR : _URC_FATAL_PHASE1_ERROR; + } +} + +static _Unwind_Reason_Code +unwind_phase2_forced(unw_context_t *uc, + _Unwind_Exception *exception_object, + _Unwind_Stop_Fn stop, void *stop_parameter) { + unw_cursor_t cursor2; + unw_init_local(&cursor2, uc); + + // Walk each frame until we reach where search phase said to stop + while (unw_step(&cursor2) > 0) { + + // Update info about this frame. + unw_proc_info_t frameInfo; + if (unw_get_proc_info(&cursor2, &frameInfo) != UNW_ESUCCESS) { + _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): unw_step " + "failed => _URC_END_OF_STACK", + (void *)exception_object); + return _URC_FATAL_PHASE2_ERROR; + } + + // When tracing, print state information. + if (_LIBUNWIND_TRACING_UNWINDING) { + char functionBuf[512]; + const char *functionName = functionBuf; + unw_word_t offset; + if ((unw_get_proc_name(&cursor2, functionBuf, sizeof(functionBuf), + &offset) != UNW_ESUCCESS) || + (frameInfo.start_ip + offset > frameInfo.end_ip)) + functionName = ".anonymous."; + _LIBUNWIND_TRACE_UNWINDING( + "unwind_phase2_forced(ex_ojb=%p): start_ip=0x%" PRIx64 + ", func=%s, lsda=0x%" PRIx64 ", personality=0x%" PRIx64, + (void *)exception_object, frameInfo.start_ip, functionName, + frameInfo.lsda, frameInfo.handler); + } + + // Call stop function at each frame. + _Unwind_Action action = + (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE); + _Unwind_Reason_Code stopResult = + (*stop)(1, action, exception_object->exception_class, exception_object, + (struct _Unwind_Context *)(&cursor2), stop_parameter); + _LIBUNWIND_TRACE_UNWINDING( + "unwind_phase2_forced(ex_ojb=%p): stop function returned %d", + (void *)exception_object, stopResult); + if (stopResult != _URC_NO_REASON) { + _LIBUNWIND_TRACE_UNWINDING( + "unwind_phase2_forced(ex_ojb=%p): stopped by stop function", + (void *)exception_object); + return _URC_FATAL_PHASE2_ERROR; + } + + // If there is a personality routine, tell it we are unwinding. + if (frameInfo.handler != 0) { + __personality_routine p = + (__personality_routine)(intptr_t)(frameInfo.handler); + _LIBUNWIND_TRACE_UNWINDING( + "unwind_phase2_forced(ex_ojb=%p): calling personality function %p", + (void *)exception_object, (void *)(uintptr_t)p); + _Unwind_Reason_Code personalityResult = + (*p)(1, action, exception_object->exception_class, exception_object, + (struct _Unwind_Context *)(&cursor2)); + switch (personalityResult) { + case _URC_CONTINUE_UNWIND: + _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): " + "personality returned " + "_URC_CONTINUE_UNWIND", + (void *)exception_object); + // Destructors called, continue unwinding + break; + case _URC_INSTALL_CONTEXT: + _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): " + "personality returned " + "_URC_INSTALL_CONTEXT", + (void *)exception_object); + // We may get control back if landing pad calls _Unwind_Resume(). + unw_resume(&cursor2); + break; + default: + // Personality routine returned an unknown result code. + _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): " + "personality returned %d, " + "_URC_FATAL_PHASE2_ERROR", + (void *)exception_object, personalityResult); + return _URC_FATAL_PHASE2_ERROR; + } + } + } + + // Call stop function one last time and tell it we've reached the end + // of the stack. + _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): calling stop " + "function with _UA_END_OF_STACK", + (void *)exception_object); + _Unwind_Action lastAction = + (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE | _UA_END_OF_STACK); + (*stop)(1, lastAction, exception_object->exception_class, exception_object, + (struct _Unwind_Context *)(&cursor2), stop_parameter); + + // Clean up phase did not resume at the frame that the search phase said it + // would. + return _URC_FATAL_PHASE2_ERROR; +} + +/// Called by \c __cxa_throw(). Only returns if there is a fatal error. +_LIBUNWIND_EXPORT _Unwind_Reason_Code +_Unwind_RaiseException(_Unwind_Exception *exception_object) { + _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)", + (void *)exception_object); + + // Mark that this is a non-forced unwind, so _Unwind_Resume() + // can do the right thing. + memset(exception_object->private_, 0, sizeof(exception_object->private_)); + + // phase 1: the search phase + // We'll let the system do that for us. + RaiseException(STATUS_GCC_THROW, 0, 1, (ULONG_PTR *)&exception_object); + + // If we get here, either something went horribly wrong or we reached the + // top of the stack. Either way, let libc++abi call std::terminate(). + return _URC_END_OF_STACK; +} + +/// When \c _Unwind_RaiseException() is in phase2, it hands control +/// to the personality function at each frame. The personality +/// may force a jump to a landing pad in that function; the landing +/// pad code may then call \c _Unwind_Resume() to continue with the +/// unwinding. Note: the call to \c _Unwind_Resume() is from compiler +/// geneated user code. All other \c _Unwind_* routines are called +/// by the C++ runtime \c __cxa_* routines. +/// +/// Note: re-throwing an exception (as opposed to continuing the unwind) +/// is implemented by having the code call \c __cxa_rethrow() which +/// in turn calls \c _Unwind_Resume_or_Rethrow(). +_LIBUNWIND_EXPORT void +_Unwind_Resume(_Unwind_Exception *exception_object) { + _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)", (void *)exception_object); + + if (exception_object->private_[0] != 0) { + unw_context_t uc; + + unw_getcontext(&uc); + unwind_phase2_forced(&uc, exception_object, + (_Unwind_Stop_Fn) exception_object->private_[0], + (void *)exception_object->private_[4]); + } else { + // Recover the parameters for the unwind from the exception object + // so we can start unwinding again. + EXCEPTION_RECORD ms_exc; + CONTEXT ms_ctx; + UNWIND_HISTORY_TABLE hist; + + ms_exc.ExceptionCode = STATUS_GCC_THROW; + ms_exc.ExceptionFlags = EXCEPTION_NONCONTINUABLE; + ms_exc.NumberParameters = 4; + ms_exc.ExceptionInformation[0] = (ULONG_PTR)exception_object; + ms_exc.ExceptionInformation[1] = exception_object->private_[1]; + ms_exc.ExceptionInformation[2] = exception_object->private_[2]; + ms_exc.ExceptionInformation[3] = exception_object->private_[3]; + RtlUnwindEx((PVOID)exception_object->private_[1], + (PVOID)exception_object->private_[2], &ms_exc, + exception_object, &ms_ctx, &hist); + } + + // Clients assume _Unwind_Resume() does not return, so all we can do is abort. + _LIBUNWIND_ABORT("_Unwind_Resume() can't return"); +} + +/// Not used by C++. +/// Unwinds stack, calling "stop" function at each frame. +/// Could be used to implement \c longjmp(). +_LIBUNWIND_EXPORT _Unwind_Reason_Code +_Unwind_ForcedUnwind(_Unwind_Exception *exception_object, + _Unwind_Stop_Fn stop, void *stop_parameter) { + _LIBUNWIND_TRACE_API("_Unwind_ForcedUnwind(ex_obj=%p, stop=%p)", + (void *)exception_object, (void *)(uintptr_t)stop); + unw_context_t uc; + unw_getcontext(&uc); + + // Mark that this is a forced unwind, so _Unwind_Resume() can do + // the right thing. + exception_object->private_[0] = (uintptr_t) stop; + exception_object->private_[4] = (uintptr_t) stop_parameter; + + // do it + return unwind_phase2_forced(&uc, exception_object, stop, stop_parameter); +} + +/// Called by personality handler during phase 2 to get LSDA for current frame. +_LIBUNWIND_EXPORT uintptr_t +_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) { + uintptr_t result = (uintptr_t)_unw_seh_get_disp_ctx((unw_cursor_t *)context)->HandlerData; + _LIBUNWIND_TRACE_API( + "_Unwind_GetLanguageSpecificData(context=%p) => 0x%" PRIxPTR, + (void *)context, result); + return result; +} + +/// Called by personality handler during phase 2 to find the start of the +/// function. +_LIBUNWIND_EXPORT uintptr_t +_Unwind_GetRegionStart(struct _Unwind_Context *context) { + DISPATCHER_CONTEXT *disp = _unw_seh_get_disp_ctx((unw_cursor_t *)context); + uintptr_t result = (uintptr_t)disp->FunctionEntry->BeginAddress + disp->ImageBase; + _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%" PRIxPTR, + (void *)context, result); + return result; +} + +static int +_unw_init_seh(unw_cursor_t *cursor, CONTEXT *context) { +#ifdef _LIBUNWIND_TARGET_X86_64 + new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_x86_64>( + context, LocalAddressSpace::sThisAddressSpace); + auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor); + co->setInfoBasedOnIPRegister(); + return UNW_ESUCCESS; +#elif defined(_LIBUNWIND_TARGET_ARM) + new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_arm>( + context, LocalAddressSpace::sThisAddressSpace); + auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor); + co->setInfoBasedOnIPRegister(); + return UNW_ESUCCESS; +#else + return UNW_EINVAL; +#endif +} + +static DISPATCHER_CONTEXT * +_unw_seh_get_disp_ctx(unw_cursor_t *cursor) { +#ifdef _LIBUNWIND_TARGET_X86_64 + return reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_x86_64> *>(cursor)->getDispatcherContext(); +#elif defined(_LIBUNWIND_TARGET_ARM) + return reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm> *>(cursor)->getDispatcherContext(); +#else + return nullptr; +#endif +} + +static void +_unw_seh_set_disp_ctx(unw_cursor_t *cursor, DISPATCHER_CONTEXT *disp) { +#ifdef _LIBUNWIND_TARGET_X86_64 + reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_x86_64> *>(cursor)->setDispatcherContext(disp); +#elif defined(_LIBUNWIND_TARGET_ARM) + reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm> *>(cursor)->setDispatcherContext(disp); +#endif +} + +#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) |