167 lines
4.5 KiB
C++
167 lines
4.5 KiB
C++
/*
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* \brief Implementation of the Thread API via Linux threads
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* \author Norman Feske
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* \author Martin Stein
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* \date 2006-06-13
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*/
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/*
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* Copyright (C) 2006-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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/* Genode includes */
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#include <base/env.h>
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#include <base/thread.h>
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#include <base/snprintf.h>
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#include <base/sleep.h>
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#include <base/log.h>
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#include <linux_native_cpu/client.h>
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#include <cpu_thread/client.h>
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/* base-internal includes */
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#include <base/internal/stack.h>
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#include <base/internal/globals.h>
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/* Linux syscall bindings */
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#include <linux_syscalls.h>
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using namespace Genode;
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extern int main_thread_futex_counter;
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static void empty_signal_handler(int) { }
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static Lock &startup_lock()
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{
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static Lock lock(Lock::LOCKED);
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return lock;
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}
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/**
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* Signal handler for killing the thread
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*/
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static void thread_exit_signal_handler(int) { lx_exit(0); }
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void Thread::_thread_start()
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{
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Thread * const thread = Thread::myself();
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/* use primary stack as alternate stack for fatal signals (exceptions) */
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void *stack_base = (void *)thread->_stack->base();
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size_t stack_size = thread->_stack->top() - thread->_stack->base();
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lx_sigaltstack(stack_base, stack_size);
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if (stack_size < 0x1000)
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raw("small stack of ", stack_size, " bytes for \"", thread->name(),
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"\" may break Linux signal handling");
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/*
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* Set signal handler such that canceled system calls get not
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* transparently retried after a signal gets received.
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*/
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lx_sigaction(LX_SIGUSR1, empty_signal_handler, false);
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/* inform core about the new thread and process ID of the new thread */
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Linux_native_cpu_client native_cpu(thread->_cpu_session->native_cpu());
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native_cpu.thread_id(thread->cap(), thread->native_thread().pid, thread->native_thread().tid);
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/* wakeup 'start' function */
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startup_lock().unlock();
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thread->entry();
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/* unblock caller of 'join()' */
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thread->_join_lock.unlock();
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sleep_forever();
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}
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void Thread::_init_platform_thread(size_t weight, Type type)
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{
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/* if no cpu session is given, use it from the environment */
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if (!_cpu_session)
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_cpu_session = env_deprecated()->cpu_session();
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/* for normal threads create an object at the CPU session */
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if (type == NORMAL) {
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_thread_cap = _cpu_session->create_thread(env_deprecated()->pd_session_cap(),
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_stack->name().string(),
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Affinity::Location(),
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Weight());
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return;
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}
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/* adjust initial object state for main threads */
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native_thread().futex_counter = main_thread_futex_counter;
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_thread_cap = main_thread_cap();
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}
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void Thread::_deinit_platform_thread()
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{
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/*
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* Kill thread until it is really really dead
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*
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* We use the 'tgkill' system call to kill the thread. This system call
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* returns immediately and just flags the corresponding signal at the
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* targeted thread context. However, the thread still lives until the
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* signal flags are evaluated. When leaving this function, however, we want
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* to be sure that the thread is no more executing any code such that we
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* an safely free and unmap the thread's stack. So we call 'tgkill' in a
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* loop until we get an error indicating that the thread does not exists
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* anymore.
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*/
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for (;;) {
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/* destroy thread locally */
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int ret = lx_tgkill(native_thread().pid, native_thread().tid, LX_SIGCANCEL);
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if (ret < 0) break;
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/* if thread still exists, wait a bit and try to kill it again */
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struct timespec ts = { 0, 500 };
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lx_nanosleep(&ts, 0);
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}
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/* inform core about the killed thread */
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_cpu_session->kill_thread(_thread_cap);
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}
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void Thread::start()
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{
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/* synchronize calls of the 'start' function */
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static Lock lock;
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Lock::Guard guard(lock);
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/*
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* The first time we enter this code path, the 'start' function is
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* called by the main thread as there cannot exist other threads
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* without executing this function. When first called, we initialize
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* the thread lib here.
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*/
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static bool threadlib_initialized = false;
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if (!threadlib_initialized) {
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lx_sigaction(LX_SIGCANCEL, thread_exit_signal_handler, false);
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threadlib_initialized = true;
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}
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native_thread().tid = lx_create_thread(Thread::_thread_start, stack_top(), this);
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native_thread().pid = lx_getpid();
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/* wait until the 'thread_start' function got entered */
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startup_lock().lock();
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}
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void Thread::cancel_blocking()
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{
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Cpu_thread_client(_thread_cap).cancel_blocking();
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}
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