//===------------------------- UnwindLevel1.c -----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//
// Implements C++ ABI Exception Handling Level 1 as documented at:
// http://mentorembedded.github.io/cxx-abi/abi-eh.html
// using libunwind
//
//===----------------------------------------------------------------------===//
// ARM EHABI does not specify _Unwind_{Get,Set}{GR,IP}(). Thus, we are
// defining inline functions to delegate the function calls to
// _Unwind_VRS_{Get,Set}(). However, some applications might declare the
// function protetype directly (instead of including <unwind.h>), thus we need
// to export these functions from libunwind.so as well.
#define _LIBUNWIND_UNWIND_LEVEL1_EXTERNAL_LINKAGE 1
#include <inttypes.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "libunwind.h"
#include "unwind.h"
#include "config.h"
#if !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__)
#ifndef _LIBUNWIND_SUPPORT_SEH_UNWIND
static _Unwind_Reason_Code
unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) {
unw_init_local(cursor, uc);
// Walk each frame looking for a place to stop.
bool handlerNotFound = true;
while (handlerNotFound) {
// Ask libunwind to get next frame (skip over first which is
// _Unwind_RaiseException).
int stepResult = unw_step(cursor);
if (stepResult == 0) {
_LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): unw_step() reached "
"bottom => _URC_END_OF_STACK",
(void *)exception_object);
return _URC_END_OF_STACK;
} else if (stepResult < 0) {
_LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): unw_step failed => "
"_URC_FATAL_PHASE1_ERROR",
(void *)exception_object);
return _URC_FATAL_PHASE1_ERROR;
}
// See if frame has code to run (has personality routine).
unw_proc_info_t frameInfo;
unw_word_t sp;
if (unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
_LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): unw_get_proc_info "
"failed => _URC_FATAL_PHASE1_ERROR",
(void *)exception_object);
return _URC_FATAL_PHASE1_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(cursor, functionBuf, sizeof(functionBuf),
&offset) != UNW_ESUCCESS) ||
(frameInfo.start_ip + offset > frameInfo.end_ip))
functionName = ".anonymous.";
unw_word_t pc;
unw_get_reg(cursor, UNW_REG_IP, &pc);
_LIBUNWIND_TRACE_UNWINDING(
"unwind_phase1(ex_ojb=%p): pc=0x%" PRIxPTR ", start_ip=0x%" PRIxPTR
", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "",
(void *)exception_object, pc, frameInfo.start_ip, functionName,
frameInfo.lsda, frameInfo.handler);
}
// If there is a personality routine, ask it if it will want to stop at
// this frame.
if (frameInfo.handler != 0) {
__personality_routine p =
(__personality_routine)(uintptr_t)(frameInfo.handler);
_LIBUNWIND_TRACE_UNWINDING(
"unwind_phase1(ex_ojb=%p): calling personality function %p",
(void *)exception_object, (void *)(uintptr_t)p);
_Unwind_Reason_Code personalityResult =
(*p)(1, _UA_SEARCH_PHASE, exception_object->exception_class,
exception_object, (struct _Unwind_Context *)(cursor));
switch (personalityResult) {
case _URC_HANDLER_FOUND:
// found a catch clause or locals that need destructing in this frame
// stop search and remember stack pointer at the frame
handlerNotFound = false;
unw_get_reg(cursor, UNW_REG_SP, &sp);
exception_object->private_2 = (uintptr_t)sp;
_LIBUNWIND_TRACE_UNWINDING(
"unwind_phase1(ex_ojb=%p): _URC_HANDLER_FOUND",
(void *)exception_object);
return _URC_NO_REASON;
case _URC_CONTINUE_UNWIND:
_LIBUNWIND_TRACE_UNWINDING(
"unwind_phase1(ex_ojb=%p): _URC_CONTINUE_UNWIND",
(void *)exception_object);
// continue unwinding
break;
default:
// something went wrong
_LIBUNWIND_TRACE_UNWINDING(
"unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR",
(void *)exception_object);
return _URC_FATAL_PHASE1_ERROR;
}
}
}
return _URC_NO_REASON;
}
static _Unwind_Reason_Code
unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) {
unw_init_local(cursor, uc);
_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)",
(void *)exception_object);
// Walk each frame until we reach where search phase said to stop.
while (true) {
// Ask libunwind to get next frame (skip over first which is
// _Unwind_RaiseException).
int stepResult = unw_step(cursor);
if (stepResult == 0) {
_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): unw_step() reached "
"bottom => _URC_END_OF_STACK",
(void *)exception_object);
return _URC_END_OF_STACK;
} else if (stepResult < 0) {
_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): unw_step failed => "
"_URC_FATAL_PHASE1_ERROR",
(void *)exception_object);
return _URC_FATAL_PHASE2_ERROR;
}
// Get info about this frame.
unw_word_t sp;
unw_proc_info_t frameInfo;
unw_get_reg(cursor, UNW_REG_SP, &sp);
if (unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): unw_get_proc_info "
"failed => _URC_FATAL_PHASE1_ERROR",
(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(cursor, functionBuf, sizeof(functionBuf),
&offset) != UNW_ESUCCESS) ||
(frameInfo.start_ip + offset > frameInfo.end_ip))
functionName = ".anonymous.";
_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIxPTR
", func=%s, sp=0x%" PRIxPTR ", lsda=0x%" PRIxPTR
", personality=0x%" PRIxPTR,
(void *)exception_object, frameInfo.start_ip,
functionName, sp, frameInfo.lsda,
frameInfo.handler);
}
// If there is a personality routine, tell it we are unwinding.
if (frameInfo.handler != 0) {
__personality_routine p =
(__personality_routine)(uintptr_t)(frameInfo.handler);
_Unwind_Action action = _UA_CLEANUP_PHASE;
if (sp == exception_object->private_2) {
// Tell personality this was the frame it marked in phase 1.
action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME);
}
_Unwind_Reason_Code personalityResult =
(*p)(1, action, exception_object->exception_class, exception_object,
(struct _Unwind_Context *)(cursor));
switch (personalityResult) {
case _URC_CONTINUE_UNWIND:
// Continue unwinding
_LIBUNWIND_TRACE_UNWINDING(
"unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND",
(void *)exception_object);
if (sp == exception_object->private_2) {
// Phase 1 said we would stop at this frame, but we did not...
_LIBUNWIND_ABORT("during phase1 personality function said it would "
"stop here, but now in phase2 it did not stop here");
}
break;
case _URC_INSTALL_CONTEXT:
_LIBUNWIND_TRACE_UNWINDING(
"unwind_phase2(ex_ojb=%p): _URC_INSTALL_CONTEXT",
(void *)exception_object);
// Personality routine says to transfer control to landing pad.
// We may get control back if landing pad calls _Unwind_Resume().
if (_LIBUNWIND_TRACING_UNWINDING) {
unw_word_t pc;
unw_get_reg(cursor, UNW_REG_IP, &pc);
unw_get_reg(cursor, UNW_REG_SP, &sp);
_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering "
"user code with ip=0x%" PRIxPTR
", sp=0x%" PRIxPTR,
(void *)exception_object, pc, sp);
}
unw_resume(cursor);
// unw_resume() only returns if there was an error.
return _URC_FATAL_PHASE2_ERROR;
default:
// Personality routine returned an unknown result code.
_LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d",
personalityResult);
return _URC_FATAL_PHASE2_ERROR;
}
}
}
// Clean up phase did not resume at the frame that the search phase
// said it would...
return _URC_FATAL_PHASE2_ERROR;
}
static _Unwind_Reason_Code
unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
_Unwind_Exception *exception_object,
_Unwind_Stop_Fn stop, void *stop_parameter) {
unw_init_local(cursor, uc);
// Walk each frame until we reach where search phase said to stop
while (unw_step(cursor) > 0) {
// Update info about this frame.
unw_proc_info_t frameInfo;
if (unw_get_proc_info(cursor, &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(cursor, 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%" PRIxPTR
", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR,
(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 *)(cursor), 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 *)(cursor));
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(cursor);
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 *)(cursor), 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 __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);
unw_context_t uc;
unw_cursor_t cursor;
unw_getcontext(&uc);
// Mark that this is a non-forced unwind, so _Unwind_Resume()
// can do the right thing.
exception_object->private_1 = 0;
exception_object->private_2 = 0;
// phase 1: the search phase
_Unwind_Reason_Code phase1 = unwind_phase1(&uc, &cursor, exception_object);
if (phase1 != _URC_NO_REASON)
return phase1;
// phase 2: the clean up phase
return unwind_phase2(&uc, &cursor, exception_object);
}
/// When _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 _Unwind_Resume() to continue with the
/// unwinding. Note: the call to _Unwind_Resume() is from compiler
/// geneated user code. All other _Unwind_* routines are called
/// by the C++ runtime __cxa_* routines.
///
/// Note: re-throwing an exception (as opposed to continuing the unwind)
/// is implemented by having the code call __cxa_rethrow() which
/// in turn calls _Unwind_Resume_or_Rethrow().
_LIBUNWIND_EXPORT void
_Unwind_Resume(_Unwind_Exception *exception_object) {
_LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)", (void *)exception_object);
unw_context_t uc;
unw_cursor_t cursor;
unw_getcontext(&uc);
if (exception_object->private_1 != 0)
unwind_phase2_forced(&uc, &cursor, exception_object,
(_Unwind_Stop_Fn) exception_object->private_1,
(void *)exception_object->private_2);
else
unwind_phase2(&uc, &cursor, exception_object);
// 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 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_cursor_t cursor;
unw_getcontext(&uc);
// Mark that this is a forced unwind, so _Unwind_Resume() can do
// the right thing.
exception_object->private_1 = (uintptr_t) stop;
exception_object->private_2 = (uintptr_t) stop_parameter;
// do it
return unwind_phase2_forced(&uc, &cursor, 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) {
unw_cursor_t *cursor = (unw_cursor_t *)context;
unw_proc_info_t frameInfo;
uintptr_t result = 0;
if (unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
result = (uintptr_t)frameInfo.lsda;
_LIBUNWIND_TRACE_API(
"_Unwind_GetLanguageSpecificData(context=%p) => 0x%" PRIxPTR,
(void *)context, result);
if (result != 0) {
if (*((uint8_t *)result) != 0xFF)
_LIBUNWIND_DEBUG_LOG("lsda at 0x%" PRIxPTR " does not start with 0xFF",
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) {
unw_cursor_t *cursor = (unw_cursor_t *)context;
unw_proc_info_t frameInfo;
uintptr_t result = 0;
if (unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
result = (uintptr_t)frameInfo.start_ip;
_LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%" PRIxPTR,
(void *)context, result);
return result;
}
#endif // !_LIBUNWIND_SUPPORT_SEH_UNWIND
/// Called by personality handler during phase 2 if a foreign exception
// is caught.
_LIBUNWIND_EXPORT void
_Unwind_DeleteException(_Unwind_Exception *exception_object) {
_LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)",
(void *)exception_object);
if (exception_object->exception_cleanup != NULL)
(*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT,
exception_object);
}
/// Called by personality handler during phase 2 to get register values.
_LIBUNWIND_EXPORT uintptr_t
_Unwind_GetGR(struct _Unwind_Context *context, int index) {
unw_cursor_t *cursor = (unw_cursor_t *)context;
unw_word_t result;
unw_get_reg(cursor, index, &result);
_LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d) => 0x%" PRIxPTR,
(void *)context, index, result);
return (uintptr_t)result;
}
/// Called by personality handler during phase 2 to alter register values.
_LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index,
uintptr_t value) {
_LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%0" PRIxPTR
")",
(void *)context, index, value);
unw_cursor_t *cursor = (unw_cursor_t *)context;
unw_set_reg(cursor, index, value);
}
/// Called by personality handler during phase 2 to get instruction pointer.
_LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
unw_cursor_t *cursor = (unw_cursor_t *)context;
unw_word_t result;
unw_get_reg(cursor, UNW_REG_IP, &result);
_LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIxPTR,
(void *)context, result);
return (uintptr_t)result;
}
/// Called by personality handler during phase 2 to alter instruction pointer,
/// such as setting where the landing pad is, so _Unwind_Resume() will
/// start executing in the landing pad.
_LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
uintptr_t value) {
_LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%0" PRIxPTR ")",
(void *)context, value);
unw_cursor_t *cursor = (unw_cursor_t *)context;
unw_set_reg(cursor, UNW_REG_IP, value);
}
#endif // !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__)