259 lines
10 KiB
C++
259 lines
10 KiB
C++
// Copyright 2014 The Crashpad Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "client/simulate_crash_mac.h"
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#include <string.h>
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#include <sys/types.h>
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#include <iterator>
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#include "base/check_op.h"
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#include "base/logging.h"
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#include "base/mac/mach_logging.h"
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#include "base/mac/scoped_mach_port.h"
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#include "build/build_config.h"
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#include "util/mach/exc_client_variants.h"
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#include "util/mach/exception_behaviors.h"
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#include "util/mach/exception_ports.h"
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#include "util/mach/mach_extensions.h"
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#include "util/misc/implicit_cast.h"
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namespace crashpad {
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namespace {
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//! \brief Sends an exception message to an exception port in accordance with
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//! the behavior and thread state flavor it’s registered to receive.
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//!
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//! \param[in] thread, task, exception, code, code_count These parameters will
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//! be passed to the exception handler as appropriate.
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//! \param[in] cpu_context The value to use for the thread state, if \a behavior
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//! indicates that the handler should receive a thread state and if the
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//! supplied thread state matches or can be converted to \a flavor. If \a
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//! behavior requires a thread state but this argument cannot be converted
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//! to match \a flavor, `thread_get_state()` will be called to obtain a
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//! suitable thread state value.
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//! \param[in] handler The Mach exception handler to deliver the exception to.
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//! \param[in] set_state If `true` and \a behavior indicates that the handler
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//! should receive and return a thread state, a new thread state will be set
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//! by `thread_set_state()` upon successful completion of the exception
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//! handler. If `false`, this will be suppressed, even when \a behavior
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//! indicates that the handler receives and returns a thread state.
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//!
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//! \return `true` if the exception was delivered to the handler and the handler
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//! indicated success. `false` otherwise, with a warning message logged.
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bool DeliverException(thread_t thread,
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task_t task,
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exception_type_t exception,
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const mach_exception_data_t code,
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mach_msg_type_number_t code_count,
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const NativeCPUContext& cpu_context,
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const ExceptionPorts::ExceptionHandler& handler,
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bool set_state) {
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kern_return_t kr;
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bool handler_wants_state = ExceptionBehaviorHasState(handler.behavior);
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if (!handler_wants_state) {
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// Regardless of the passed-in value of |set_state|, if the handler won’t be
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// dealing with any state at all, no state should be set.
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set_state = false;
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}
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// old_state is only used if the context already captured doesn’t match (or
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// can’t be converted to) what’s registered for the handler.
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thread_state_data_t old_state;
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thread_state_flavor_t flavor = handler.flavor;
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ConstThreadState state;
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mach_msg_type_number_t state_count;
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switch (flavor) {
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#if defined(ARCH_CPU_X86_FAMILY)
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case x86_THREAD_STATE:
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state = reinterpret_cast<ConstThreadState>(&cpu_context);
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state_count = x86_THREAD_STATE_COUNT;
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break;
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#if defined(ARCH_CPU_X86)
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case x86_THREAD_STATE32:
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state = reinterpret_cast<ConstThreadState>(&cpu_context.uts.ts32);
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state_count = cpu_context.tsh.count;
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break;
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#elif defined(ARCH_CPU_X86_64)
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case x86_THREAD_STATE64:
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state = reinterpret_cast<ConstThreadState>(&cpu_context.uts.ts64);
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state_count = cpu_context.tsh.count;
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break;
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#endif
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#elif defined(ARCH_CPU_ARM64)
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case ARM_UNIFIED_THREAD_STATE:
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state = reinterpret_cast<ConstThreadState>(&cpu_context);
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state_count = ARM_UNIFIED_THREAD_STATE_COUNT;
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break;
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case ARM_THREAD_STATE64:
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state = reinterpret_cast<ConstThreadState>(&cpu_context.ts_64);
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state_count = cpu_context.ash.count;
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break;
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#else
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#error Port to your CPU architecture
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#endif
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case THREAD_STATE_NONE:
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// This is only acceptable if the handler doesn’t have one of the “state”
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// behaviors. Otherwise, if the kernel were attempting to send an
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// exception message to this port, it would call thread_getstatus() (known
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// outside the kernel as thread_get_state()) which would fail because
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// THREAD_STATE_NONE is not a valid state to get. See 10.9.5
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// xnu-2422.115.4/osfmk/kern/exception.c exception_deliver() and
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// xnu-2422.115.4/osfmk/i386/pcb.c machine_thread_get_state().
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if (!handler_wants_state) {
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state = nullptr;
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state_count = 0;
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break;
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}
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LOG(WARNING) << "exception handler has unexpected state flavor" << flavor;
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return false;
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default:
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if (!handler_wants_state) {
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// Don’t bother getting any thread state if the handler’s not actually
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// going to use it.
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state = nullptr;
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state_count = 0;
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} else {
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state = old_state;
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state_count = THREAD_STATE_MAX;
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kr = thread_get_state(thread, flavor, old_state, &state_count);
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if (kr != KERN_SUCCESS) {
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MACH_LOG(WARNING, kr) << "thread_get_state";
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return false;
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}
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}
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break;
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}
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// new_state is supposed to be an out parameter only, but in case the handler
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// doesn't touch it, make sure it's initialized to a valid thread state.
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// Otherwise, the thread_set_state() call below would set a garbage thread
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// state.
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thread_state_data_t new_state;
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size_t state_size =
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sizeof(natural_t) *
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std::min(state_count, implicit_cast<unsigned int>(THREAD_STATE_MAX));
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memcpy(new_state, state, state_size);
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mach_msg_type_number_t new_state_count = THREAD_STATE_MAX;
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kr = UniversalExceptionRaise(handler.behavior,
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handler.port,
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thread,
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task,
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exception,
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code,
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code_count,
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&flavor,
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state,
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state_count,
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new_state,
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&new_state_count);
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// The kernel treats a return value of MACH_RCV_PORT_DIED as successful,
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// although it will not set a new thread state in that case. See 10.9.5
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// xnu-2422.115.4/osfmk/kern/exception.c exception_deliver(), and the more
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// elaborate comment at util/mach/exc_server_variants.h
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// ExcServerSuccessfulReturnValue(). Duplicate that behavior.
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bool success = kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED;
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MACH_LOG_IF(WARNING, !success, kr) << "UniversalExceptionRaise";
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if (kr == KERN_SUCCESS && set_state) {
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kr = thread_set_state(thread, flavor, new_state, new_state_count);
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MACH_LOG_IF(WARNING, kr != KERN_SUCCESS, kr) << "thread_set_state";
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}
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return success;
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}
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} // namespace
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void SimulateCrash(const NativeCPUContext& cpu_context) {
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#if defined(ARCH_CPU_X86)
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DCHECK_EQ(implicit_cast<thread_state_flavor_t>(cpu_context.tsh.flavor),
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implicit_cast<thread_state_flavor_t>(x86_THREAD_STATE32));
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DCHECK_EQ(implicit_cast<mach_msg_type_number_t>(cpu_context.tsh.count),
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x86_THREAD_STATE32_COUNT);
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#elif defined(ARCH_CPU_X86_64)
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DCHECK_EQ(implicit_cast<thread_state_flavor_t>(cpu_context.tsh.flavor),
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implicit_cast<thread_state_flavor_t>(x86_THREAD_STATE64));
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DCHECK_EQ(implicit_cast<mach_msg_type_number_t>(cpu_context.tsh.count),
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x86_THREAD_STATE64_COUNT);
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#elif defined(ARCH_CPU_ARM64)
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DCHECK_EQ(implicit_cast<thread_state_flavor_t>(cpu_context.ash.flavor),
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implicit_cast<thread_state_flavor_t>(ARM_THREAD_STATE64));
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DCHECK_EQ(implicit_cast<mach_msg_type_number_t>(cpu_context.ash.count),
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ARM_THREAD_STATE64_COUNT);
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#else
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#error Port to your CPU architecture
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#endif
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base::mac::ScopedMachSendRight thread(mach_thread_self());
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exception_type_t exception = kMachExceptionSimulated;
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mach_exception_data_type_t codes[] = {0, 0};
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mach_msg_type_number_t code_count = std::size(codes);
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// Look up the handler for EXC_CRASH exceptions in the same way that the
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// kernel would: try a thread handler, then a task handler, and finally a host
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// handler. 10.9.5 xnu-2422.115.4/osfmk/kern/exception.c exception_triage().
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static constexpr ExceptionPorts::TargetType kTargetTypes[] = {
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ExceptionPorts::kTargetTypeThread,
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ExceptionPorts::kTargetTypeTask,
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// This is not expected to succeed, because mach_host_self() doesn’t
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// return the host_priv port to non-root users, and this is the port
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// that’s required for host_get_exception_ports().
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//
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// See 10.9.5 xnu-2422.115.4/bsd/kern/kern_prot.c set_security_token(),
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// xnu-2422.115.4/osfmk/kern/task.c host_security_set_task_token(), and
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// xnu-2422.115.4/osfmk/kern/ipc_host.c host_get_exception_ports().
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ExceptionPorts::kTargetTypeHost,
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};
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bool success = false;
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for (size_t target_type_index = 0;
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!success && target_type_index < std::size(kTargetTypes);
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++target_type_index) {
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ExceptionPorts::ExceptionHandlerVector handlers;
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ExceptionPorts exception_ports(kTargetTypes[target_type_index],
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MACH_PORT_NULL);
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if (exception_ports.GetExceptionPorts(EXC_MASK_CRASH, &handlers)) {
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DCHECK_LE(handlers.size(), 1u);
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if (handlers.size() == 1) {
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DCHECK(handlers[0].mask & EXC_MASK_CRASH);
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success = DeliverException(thread.get(),
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mach_task_self(),
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exception,
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codes,
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code_count,
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cpu_context,
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handlers[0],
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false);
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}
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}
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}
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LOG_IF(WARNING, !success)
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<< "SimulateCrash did not find an appropriate exception handler";
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}
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} // namespace crashpad
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