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pthread: remove use of private Native_config API
Former Native_config::context_area_virtual_base() was used to identify the main, which is not desired as the Native_config is rather low-level (almost private to the base libs). The commit uses a library constructor to retrieve the main-thread Thread_base pointer, which can be used later to distinguish main and other threads.
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@ -44,6 +44,19 @@ static Lock pthread_cleanup_list_lock;
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static List<thread_cleanup> pthread_cleanup_list;
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/*
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* We initialize the main-thread pointer in a constructor depending on the
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* assumption that libpthread is loaded on application startup by ldso. During
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* this stage only the main thread is executed.
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*/
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static __attribute__((constructor)) Thread_base * main_thread()
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{
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static Thread_base *thread = Thread_base::myself();
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return thread;
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}
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extern "C" {
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/* Thread */
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@ -105,6 +118,13 @@ extern "C" {
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}
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/* special non-POSIX function (for example used in libresolv) */
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int _pthread_main_np(void)
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{
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return (Thread_base::myself() == main_thread());
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}
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pthread_t pthread_self(void)
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{
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Thread_base *myself = Thread_base::myself();
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@ -113,39 +133,36 @@ extern "C" {
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if (pthread)
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return pthread;
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/* either it is the main thread, an alien thread or a bug */
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/*
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* We pass here if the main thread or an alien thread calls
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* pthread_self(). So check for aliens (or other bugs) and opt-out
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* early.
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*/
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/* determine name of thread */
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if (!_pthread_main_np()) {
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char name[Thread_base::Context::NAME_LEN];
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myself->name(name, sizeof(name));
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/* determine if stack is in first context area slot */
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addr_t stack = reinterpret_cast<addr_t>(&myself);
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bool is_main = Native_config::context_area_virtual_base() <= stack &&
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stack < Native_config::context_area_virtual_base() +
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Native_config::context_virtual_size();
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/* check that stack and name is of main thread */
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if (is_main && !strcmp(name, "main")) {
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/* create a pthread object containing copy of main Thread_base */
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static struct pthread_attr main_thread_attr;
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static struct pthread *main = nullptr;
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if (!main) {
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/*
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* The pthread object does not get deleted, because this would
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* also delete the 'Thread_base' of the main thread.
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*/
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main = new (Genode::env()->heap()) struct pthread(*myself, &main_thread_attr);
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}
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return main;
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}
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PERR("pthread_self() called from alien thread named '%s'", name);
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return nullptr;
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}
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/*
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* We create a pthread object containing a copy of main thread's
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* Thread_base object. Therefore, we ensure the pthread object does not
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* get deleted by allocating it in heap via new(). Otherwise, the
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* static destruction of the pthread object would also destruct the
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* 'Thread_base' of the main thread.
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*/
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static struct pthread_attr main_thread_attr;
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static struct pthread *main = new (Genode::env()->heap())
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struct pthread(*myself, &main_thread_attr);
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return main;
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}
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int pthread_attr_getstack(const pthread_attr_t *attr,
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void **stackaddr,
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@ -182,12 +199,6 @@ extern "C" {
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}
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int _pthread_main_np(void)
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{
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return (Thread_base::myself() == 0);
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}
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/* Mutex */
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