//===-- MachException.cpp ---------------------------------------*- 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
//
//===----------------------------------------------------------------------===//
//
// Created by Greg Clayton on 6/18/07.
//
//===----------------------------------------------------------------------===//
#include "MachException.h"
#include "DNB.h"
#include "DNBError.h"
#include "DNBLog.h"
#include "MachProcess.h"
#include "PThreadMutex.h"
#include "SysSignal.h"
#include <cerrno>
#include <sys/ptrace.h>
#include <sys/types.h>
// Routine mach_exception_raise
extern "C" kern_return_t
catch_mach_exception_raise(mach_port_t exception_port, mach_port_t thread,
mach_port_t task, exception_type_t exception,
mach_exception_data_t code,
mach_msg_type_number_t codeCnt);
extern "C" kern_return_t catch_mach_exception_raise_state(
mach_port_t exception_port, exception_type_t exception,
const mach_exception_data_t code, mach_msg_type_number_t codeCnt,
int *flavor, const thread_state_t old_state,
mach_msg_type_number_t old_stateCnt, thread_state_t new_state,
mach_msg_type_number_t *new_stateCnt);
// Routine mach_exception_raise_state_identity
extern "C" kern_return_t catch_mach_exception_raise_state_identity(
mach_port_t exception_port, mach_port_t thread, mach_port_t task,
exception_type_t exception, mach_exception_data_t code,
mach_msg_type_number_t codeCnt, int *flavor, thread_state_t old_state,
mach_msg_type_number_t old_stateCnt, thread_state_t new_state,
mach_msg_type_number_t *new_stateCnt);
extern "C" boolean_t mach_exc_server(mach_msg_header_t *InHeadP,
mach_msg_header_t *OutHeadP);
// Note: g_message points to the storage allocated to catch the data from
// catching the current exception raise. It's populated when we catch a raised
// exception which can't immediately be replied to.
//
// If it becomes possible to catch exceptions from multiple threads
// simultaneously, accesses to g_message would need to be mutually exclusive.
static MachException::Data *g_message = NULL;
extern "C" kern_return_t catch_mach_exception_raise_state(
mach_port_t exc_port, exception_type_t exc_type,
const mach_exception_data_t exc_data, mach_msg_type_number_t exc_data_count,
int *flavor, const thread_state_t old_state,
mach_msg_type_number_t old_stateCnt, thread_state_t new_state,
mach_msg_type_number_t *new_stateCnt) {
if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {
DNBLogThreaded("::%s ( exc_port = 0x%4.4x, exc_type = %d ( %s ), exc_data "
"= 0x%llx, exc_data_count = %d)",
__FUNCTION__, exc_port, exc_type,
MachException::Name(exc_type), (uint64_t)exc_data,
exc_data_count);
}
return KERN_FAILURE;
}
extern "C" kern_return_t catch_mach_exception_raise_state_identity(
mach_port_t exc_port, mach_port_t thread_port, mach_port_t task_port,
exception_type_t exc_type, mach_exception_data_t exc_data,
mach_msg_type_number_t exc_data_count, int *flavor,
thread_state_t old_state, mach_msg_type_number_t old_stateCnt,
thread_state_t new_state, mach_msg_type_number_t *new_stateCnt) {
if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {
DNBLogThreaded("::%s ( exc_port = 0x%4.4x, thd_port = 0x%4.4x, tsk_port = "
"0x%4.4x, exc_type = %d ( %s ), exc_data[%d] = { 0x%llx, "
"0x%llx })",
__FUNCTION__, exc_port, thread_port, task_port, exc_type,
MachException::Name(exc_type), exc_data_count,
(uint64_t)(exc_data_count > 0 ? exc_data[0] : 0xBADDBADD),
(uint64_t)(exc_data_count > 1 ? exc_data[1] : 0xBADDBADD));
}
return KERN_FAILURE;
}
extern "C" kern_return_t
catch_mach_exception_raise(mach_port_t exc_port, mach_port_t thread_port,
mach_port_t task_port, exception_type_t exc_type,
mach_exception_data_t exc_data,
mach_msg_type_number_t exc_data_count) {
if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {
std::vector<uint64_t> exc_datas;
uint64_t tmp;
for (unsigned i = 0; i < exc_data_count; ++i) {
// Perform an unaligned copy.
memcpy(&tmp, &exc_data[i], sizeof(uint64_t));
exc_datas.push_back(tmp);
}
DNBLogThreaded("::%s ( exc_port = 0x%4.4x, thd_port = 0x%4.4x, tsk_port = "
"0x%4.4x, exc_type = %d ( %s ), exc_data[%d] = { 0x%llx, "
"0x%llx })",
__FUNCTION__, exc_port, thread_port, task_port, exc_type,
MachException::Name(exc_type), exc_data_count,
(uint64_t)(exc_data_count > 0 ? exc_datas[0] : 0xBADDBADD),
(uint64_t)(exc_data_count > 1 ? exc_datas[1] : 0xBADDBADD));
}
g_message->exc_type = 0;
g_message->exc_data.clear();
if (task_port == g_message->task_port) {
g_message->task_port = task_port;
g_message->thread_port = thread_port;
g_message->exc_type = exc_type;
g_message->AppendExceptionData(exc_data, exc_data_count);
return KERN_SUCCESS;
} else if (!MachTask::IsValid(g_message->task_port)) {
// Our original exception port isn't valid anymore check for a SIGTRAP
if (exc_type == EXC_SOFTWARE && exc_data_count == 2 &&
exc_data[0] == EXC_SOFT_SIGNAL && exc_data[1] == SIGTRAP) {
// We got a SIGTRAP which indicates we might have exec'ed and possibly
// lost our old task port during the exec, so we just need to switch over
// to using this new task port
g_message->task_port = task_port;
g_message->thread_port = thread_port;
g_message->exc_type = exc_type;
g_message->AppendExceptionData(exc_data, exc_data_count);
return KERN_SUCCESS;
}
}
return KERN_FAILURE;
}
void MachException::Message::Dump() const {
DNBLogThreadedIf(LOG_EXCEPTIONS, " exc_msg { bits = 0x%8.8x size = 0x%8.8x "
"remote-port = 0x%8.8x local-port = 0x%8.8x "
"reserved = 0x%8.8x id = 0x%8.8x } ",
exc_msg.hdr.msgh_bits, exc_msg.hdr.msgh_size,
exc_msg.hdr.msgh_remote_port, exc_msg.hdr.msgh_local_port,
exc_msg.hdr.msgh_reserved, exc_msg.hdr.msgh_id);
DNBLogThreadedIf(LOG_EXCEPTIONS, "reply_msg { bits = 0x%8.8x size = 0x%8.8x "
"remote-port = 0x%8.8x local-port = 0x%8.8x "
"reserved = 0x%8.8x id = 0x%8.8x }",
reply_msg.hdr.msgh_bits, reply_msg.hdr.msgh_size,
reply_msg.hdr.msgh_remote_port,
reply_msg.hdr.msgh_local_port, reply_msg.hdr.msgh_reserved,
reply_msg.hdr.msgh_id);
state.Dump();
}
bool MachException::Data::GetStopInfo(
struct DNBThreadStopInfo *stop_info) const {
// Zero out the structure.
memset(stop_info, 0, sizeof(struct DNBThreadStopInfo));
if (exc_type == 0) {
stop_info->reason = eStopTypeInvalid;
return true;
}
#if defined(__arm64__) || defined(__aarch64__)
if (exc_type == EXC_BREAKPOINT && exc_data[0] == EXC_ARM_DA_DEBUG &&
exc_data.size() > 1) {
stop_info->reason = eStopTypeWatchpoint;
stop_info->details.watchpoint.mach_exception_addr = exc_data[1];
stop_info->details.watchpoint.addr = INVALID_NUB_ADDRESS;
if (exc_data.size() > 2) {
stop_info->details.watchpoint.hw_idx = exc_data[2];
}
return true;
}
#endif
// We always stop with a mach exceptions
stop_info->reason = eStopTypeException;
// Save the EXC_XXXX exception type
stop_info->details.exception.type = exc_type;
// Fill in a text description
const char *exc_name = MachException::Name(exc_type);
char *desc = stop_info->description;
const char *end_desc = desc + DNB_THREAD_STOP_INFO_MAX_DESC_LENGTH;
if (exc_name)
desc +=
snprintf(desc, DNB_THREAD_STOP_INFO_MAX_DESC_LENGTH, "%s", exc_name);
else
desc +=
snprintf(desc, DNB_THREAD_STOP_INFO_MAX_DESC_LENGTH, "%i", exc_type);
stop_info->details.exception.data_count = exc_data.size();
int soft_signal = SoftSignal();
if (soft_signal) {
if (desc < end_desc) {
const char *sig_str = SysSignal::Name(soft_signal);
snprintf(desc, end_desc - desc, " EXC_SOFT_SIGNAL( %i ( %s ))",
soft_signal, sig_str ? sig_str : "unknown signal");
}
} else {
// No special disassembly for exception data, just
size_t idx;
if (desc < end_desc) {
desc += snprintf(desc, end_desc - desc, " data[%llu] = {",
(uint64_t)stop_info->details.exception.data_count);
for (idx = 0;
desc < end_desc && idx < stop_info->details.exception.data_count;
++idx)
desc += snprintf(
desc, end_desc - desc, "0x%llx%c", (uint64_t)exc_data[idx],
((idx + 1 == stop_info->details.exception.data_count) ? '}' : ','));
}
}
// Copy the exception data
size_t i;
for (i = 0; i < stop_info->details.exception.data_count; i++)
stop_info->details.exception.data[i] = exc_data[i];
return true;
}
void MachException::Data::DumpStopReason() const {
int soft_signal = SoftSignal();
if (soft_signal) {
const char *signal_str = SysSignal::Name(soft_signal);
if (signal_str)
DNBLog("signal(%s)", signal_str);
else
DNBLog("signal(%i)", soft_signal);
return;
}
DNBLog("%s", Name(exc_type));
}
kern_return_t MachException::Message::Receive(mach_port_t port,
mach_msg_option_t options,
mach_msg_timeout_t timeout,
mach_port_t notify_port) {
DNBError err;
const bool log_exceptions = DNBLogCheckLogBit(LOG_EXCEPTIONS);
mach_msg_timeout_t mach_msg_timeout =
(options & MACH_RCV_TIMEOUT) ? timeout : 0;
if (log_exceptions && ((options & MACH_RCV_TIMEOUT) == 0)) {
// Dump this log message if we have no timeout in case it never returns
DNBLogThreaded("::mach_msg ( msg->{bits = %#x, size = %u remote_port = "
"%#x, local_port = %#x, reserved = 0x%x, id = 0x%x}, option "
"= %#x, send_size = 0, rcv_size = %llu, rcv_name = %#x, "
"timeout = %u, notify = %#x)",
exc_msg.hdr.msgh_bits, exc_msg.hdr.msgh_size,
exc_msg.hdr.msgh_remote_port, exc_msg.hdr.msgh_local_port,
exc_msg.hdr.msgh_reserved, exc_msg.hdr.msgh_id, options,
(uint64_t)sizeof(exc_msg.data), port, mach_msg_timeout,
notify_port);
}
err = ::mach_msg(&exc_msg.hdr,
options, // options
0, // Send size
sizeof(exc_msg.data), // Receive size
port, // exception port to watch for exception on
mach_msg_timeout, // timeout in msec (obeyed only if
// MACH_RCV_TIMEOUT is ORed into the
// options parameter)
notify_port);
// Dump any errors we get
if (log_exceptions) {
err.LogThreaded("::mach_msg ( msg->{bits = %#x, size = %u remote_port = "
"%#x, local_port = %#x, reserved = 0x%x, id = 0x%x}, "
"option = %#x, send_size = %u, rcv_size = %u, rcv_name = "
"%#x, timeout = %u, notify = %#x)",
exc_msg.hdr.msgh_bits, exc_msg.hdr.msgh_size,
exc_msg.hdr.msgh_remote_port, exc_msg.hdr.msgh_local_port,
exc_msg.hdr.msgh_reserved, exc_msg.hdr.msgh_id, options, 0,
sizeof(exc_msg.data), port, mach_msg_timeout, notify_port);
}
return err.Status();
}
bool MachException::Message::CatchExceptionRaise(task_t task) {
bool success = false;
state.task_port = task;
g_message = &state;
// The exc_server function is the MIG generated server handling function
// to handle messages from the kernel relating to the occurrence of an
// exception in a thread. Such messages are delivered to the exception port
// set via thread_set_exception_ports or task_set_exception_ports. When an
// exception occurs in a thread, the thread sends an exception message to
// its exception port, blocking in the kernel waiting for the receipt of a
// reply. The exc_server function performs all necessary argument handling
// for this kernel message and calls catch_exception_raise,
// catch_exception_raise_state or catch_exception_raise_state_identity,
// which should handle the exception. If the called routine returns
// KERN_SUCCESS, a reply message will be sent, allowing the thread to
// continue from the point of the exception; otherwise, no reply message
// is sent and the called routine must have dealt with the exception
// thread directly.
if (mach_exc_server(&exc_msg.hdr, &reply_msg.hdr)) {
success = true;
} else if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {
DNBLogThreaded("mach_exc_server returned zero...");
}
g_message = NULL;
return success;
}
kern_return_t MachException::Message::Reply(MachProcess *process, int signal) {
// Reply to the exception...
DNBError err;
// If we had a soft signal, we need to update the thread first so it can
// continue without signaling
int soft_signal = state.SoftSignal();
if (soft_signal) {
int state_pid = -1;
if (process->Task().TaskPort() == state.task_port) {
// This is our task, so we can update the signal to send to it
state_pid = process->ProcessID();
soft_signal = signal;
} else {
err = ::pid_for_task(state.task_port, &state_pid);
}
assert(state_pid != -1);
if (state_pid != -1) {
errno = 0;
if (::ptrace(PT_THUPDATE, state_pid,
(caddr_t)((uintptr_t)state.thread_port), soft_signal) != 0)
err.SetError(errno, DNBError::POSIX);
else
err.Clear();
if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail())
err.LogThreaded("::ptrace (request = PT_THUPDATE, pid = 0x%4.4x, tid = "
"0x%4.4x, signal = %i)",
state_pid, state.thread_port, soft_signal);
}
}
DNBLogThreadedIf(
LOG_EXCEPTIONS, "::mach_msg ( msg->{bits = %#x, size = %u, remote_port = "
"%#x, local_port = %#x, reserved = 0x%x, id = 0x%x}, "
"option = %#x, send_size = %u, rcv_size = %u, rcv_name = "
"%#x, timeout = %u, notify = %#x)",
reply_msg.hdr.msgh_bits, reply_msg.hdr.msgh_size,
reply_msg.hdr.msgh_remote_port, reply_msg.hdr.msgh_local_port,
reply_msg.hdr.msgh_reserved, reply_msg.hdr.msgh_id,
MACH_SEND_MSG | MACH_SEND_INTERRUPT, reply_msg.hdr.msgh_size, 0,
MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
err = ::mach_msg(&reply_msg.hdr, MACH_SEND_MSG | MACH_SEND_INTERRUPT,
reply_msg.hdr.msgh_size, 0, MACH_PORT_NULL,
MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
if (err.Fail()) {
if (err.Status() == MACH_SEND_INTERRUPTED) {
if (DNBLogCheckLogBit(LOG_EXCEPTIONS))
err.LogThreaded("::mach_msg() - send interrupted");
// TODO: keep retrying to reply???
} else {
if (state.task_port == process->Task().TaskPort()) {
DNBLogThreaded("error: mach_msg() returned an error when replying to a "
"mach exception: error = %u",
err.Status());
} else {
if (DNBLogCheckLogBit(LOG_EXCEPTIONS))
err.LogThreaded("::mach_msg() - failed (child of task)");
}
}
}
return err.Status();
}
void MachException::Data::Dump() const {
const char *exc_type_name = MachException::Name(exc_type);
DNBLogThreadedIf(
LOG_EXCEPTIONS, " state { task_port = 0x%4.4x, thread_port = "
"0x%4.4x, exc_type = %i (%s) ...",
task_port, thread_port, exc_type, exc_type_name ? exc_type_name : "???");
const size_t exc_data_count = exc_data.size();
// Dump any special exception data contents
int soft_signal = SoftSignal();
if (soft_signal != 0) {
const char *sig_str = SysSignal::Name(soft_signal);
DNBLogThreadedIf(LOG_EXCEPTIONS,
" exc_data: EXC_SOFT_SIGNAL (%i (%s))",
soft_signal, sig_str ? sig_str : "unknown signal");
} else {
// No special disassembly for this data, just dump the data
size_t idx;
for (idx = 0; idx < exc_data_count; ++idx) {
DNBLogThreadedIf(LOG_EXCEPTIONS, " exc_data[%llu]: 0x%llx",
(uint64_t)idx, (uint64_t)exc_data[idx]);
}
}
}
// The EXC_MASK_ALL value hard-coded here so that lldb can be built
// on a new OS with an older deployment target . The new OS may have
// an addition to its EXC_MASK_ALL that the old OS will not recognize -
// <mach/exception_types.h> doesn't vary the value based on the deployment
// target. So we need a known set of masks that can be assumed to be
// valid when running on an older OS. We'll fall back to trying
// PREV_EXC_MASK_ALL if the EXC_MASK_ALL value lldb was compiled with is
// not recognized.
#define PREV_EXC_MASK_ALL (EXC_MASK_BAD_ACCESS | \
EXC_MASK_BAD_INSTRUCTION | \
EXC_MASK_ARITHMETIC | \
EXC_MASK_EMULATION | \
EXC_MASK_SOFTWARE | \
EXC_MASK_BREAKPOINT | \
EXC_MASK_SYSCALL | \
EXC_MASK_MACH_SYSCALL | \
EXC_MASK_RPC_ALERT | \
EXC_MASK_RESOURCE | \
EXC_MASK_GUARD | \
EXC_MASK_MACHINE)
#define LLDB_EXC_MASK EXC_MASK_ALL
kern_return_t MachException::PortInfo::Save(task_t task) {
DNBLogThreadedIf(LOG_EXCEPTIONS | LOG_VERBOSE,
"MachException::PortInfo::Save ( task = 0x%4.4x )", task);
// Be careful to be able to have debugserver built on a newer OS than what
// it is currently running on by being able to start with all exceptions
// and back off to just what is supported on the current system
DNBError err;
mask = LLDB_EXC_MASK;
count = (sizeof(ports) / sizeof(ports[0]));
err = ::task_get_exception_ports(task, mask, masks, &count, ports, behaviors,
flavors);
if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail())
err.LogThreaded("::task_get_exception_ports ( task = 0x%4.4x, mask = 0x%x, "
"maskCnt => %u, ports, behaviors, flavors )",
task, mask, count);
if (err.Status() == KERN_INVALID_ARGUMENT && mask != PREV_EXC_MASK_ALL) {
mask = PREV_EXC_MASK_ALL;
count = (sizeof(ports) / sizeof(ports[0]));
err = ::task_get_exception_ports(task, mask, masks, &count, ports,
behaviors, flavors);
if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail())
err.LogThreaded("::task_get_exception_ports ( task = 0x%4.4x, mask = "
"0x%x, maskCnt => %u, ports, behaviors, flavors )",
task, mask, count);
}
if (err.Fail()) {
mask = 0;
count = 0;
}
return err.Status();
}
kern_return_t MachException::PortInfo::Restore(task_t task) {
DNBLogThreadedIf(LOG_EXCEPTIONS | LOG_VERBOSE,
"MachException::PortInfo::Restore( task = 0x%4.4x )", task);
uint32_t i = 0;
DNBError err;
if (count > 0) {
for (i = 0; i < count; i++) {
err = ::task_set_exception_ports(task, masks[i], ports[i], behaviors[i],
flavors[i]);
if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail()) {
err.LogThreaded("::task_set_exception_ports ( task = 0x%4.4x, "
"exception_mask = 0x%8.8x, new_port = 0x%4.4x, "
"behavior = 0x%8.8x, new_flavor = 0x%8.8x )",
task, masks[i], ports[i], behaviors[i], flavors[i]);
// Bail if we encounter any errors
}
if (err.Fail())
break;
}
}
count = 0;
return err.Status();
}
const char *MachException::Name(exception_type_t exc_type) {
switch (exc_type) {
case EXC_BAD_ACCESS:
return "EXC_BAD_ACCESS";
case EXC_BAD_INSTRUCTION:
return "EXC_BAD_INSTRUCTION";
case EXC_ARITHMETIC:
return "EXC_ARITHMETIC";
case EXC_EMULATION:
return "EXC_EMULATION";
case EXC_SOFTWARE:
return "EXC_SOFTWARE";
case EXC_BREAKPOINT:
return "EXC_BREAKPOINT";
case EXC_SYSCALL:
return "EXC_SYSCALL";
case EXC_MACH_SYSCALL:
return "EXC_MACH_SYSCALL";
case EXC_RPC_ALERT:
return "EXC_RPC_ALERT";
#ifdef EXC_CRASH
case EXC_CRASH:
return "EXC_CRASH";
#endif
case EXC_RESOURCE:
return "EXC_RESOURCE";
#ifdef EXC_GUARD
case EXC_GUARD:
return "EXC_GUARD";
#endif
#ifdef EXC_CORPSE_NOTIFY
case EXC_CORPSE_NOTIFY:
return "EXC_CORPSE_NOTIFY";
#endif
#ifdef EXC_CORPSE_VARIANT_BIT
case EXC_CORPSE_VARIANT_BIT:
return "EXC_CORPSE_VARIANT_BIT";
#endif
default:
break;
}
return NULL;
}
// Returns the exception mask for a given exception name.
// 0 is not a legit mask, so we return that in the case of an error.
exception_mask_t MachException::ExceptionMask(const char *name) {
static const char *exception_prefix = "EXC_";
static const int prefix_len = strlen(exception_prefix);
// All mach exceptions start with this prefix:
if (strstr(name, exception_prefix) != name)
return 0;
name += prefix_len;
std::string name_str = name;
if (name_str == "BAD_ACCESS")
return EXC_MASK_BAD_ACCESS;
if (name_str == "BAD_INSTRUCTION")
return EXC_MASK_BAD_INSTRUCTION;
if (name_str == "ARITHMETIC")
return EXC_MASK_ARITHMETIC;
if (name_str == "EMULATION")
return EXC_MASK_EMULATION;
if (name_str == "SOFTWARE")
return EXC_MASK_SOFTWARE;
if (name_str == "BREAKPOINT")
return EXC_MASK_BREAKPOINT;
if (name_str == "SYSCALL")
return EXC_MASK_SYSCALL;
if (name_str == "MACH_SYSCALL")
return EXC_MASK_MACH_SYSCALL;
if (name_str == "RPC_ALERT")
return EXC_MASK_RPC_ALERT;
#ifdef EXC_CRASH
if (name_str == "CRASH")
return EXC_MASK_CRASH;
#endif
if (name_str == "RESOURCE")
return EXC_MASK_RESOURCE;
#ifdef EXC_GUARD
if (name_str == "GUARD")
return EXC_MASK_GUARD;
#endif
#ifdef EXC_CORPSE_NOTIFY
if (name_str == "CORPSE_NOTIFY")
return EXC_MASK_CORPSE_NOTIFY;
#endif
return 0;
}
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