X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/39236c6e673c41db228275375ab7fdb0f837b292..cc8bc92ae4a8e9f1a1ab61bf83d34ad8150b3405:/osfmk/kern/syscall_subr.c diff --git a/osfmk/kern/syscall_subr.c b/osfmk/kern/syscall_subr.c index da2fe9e74..e944c79d9 100644 --- a/osfmk/kern/syscall_subr.c +++ b/osfmk/kern/syscall_subr.c @@ -68,18 +68,22 @@ #include #include #include +#include + #include #include #include #include - +#include +#include #ifdef MACH_BSD extern void workqueue_thread_yielded(void); extern sched_call_t workqueue_get_sched_callback(void); #endif /* MACH_BSD */ +extern wait_result_t thread_handoff_reason(thread_t thread, ast_t reason); /* Called from commpage to take a delayed preemption when exiting * the "Preemption Free Zone" (PFZ). @@ -98,25 +102,18 @@ __unused struct pfz_exit_args *args) * swtch and swtch_pri both attempt to context switch (logic in * thread_block no-ops the context switch if nothing would happen). * A boolean is returned that indicates whether there is anything - * else runnable. - * - * This boolean can be used by a thread waiting on a - * lock or condition: If FALSE is returned, the thread is justified - * in becoming a resource hog by continuing to spin because there's - * nothing else useful that the processor could do. If TRUE is - * returned, the thread should make one more check on the - * lock and then be a good citizen and really suspend. + * else runnable. That's no excuse to spin, though. */ static void swtch_continue(void) { - register processor_t myprocessor; - boolean_t result; + processor_t myprocessor; + boolean_t result; - disable_preemption(); + disable_preemption(); myprocessor = current_processor(); - result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0; + result = SCHED(thread_should_yield)(myprocessor, current_thread()); enable_preemption(); thread_syscall_return(result); @@ -127,12 +124,12 @@ boolean_t swtch( __unused struct swtch_args *args) { - register processor_t myprocessor; + processor_t myprocessor; boolean_t result; disable_preemption(); myprocessor = current_processor(); - if (SCHED(processor_queue_empty)(myprocessor) && rt_runq.count == 0) { + if (!SCHED(thread_should_yield)(myprocessor, current_thread())) { mp_enable_preemption(); return (FALSE); @@ -145,7 +142,7 @@ swtch( disable_preemption(); myprocessor = current_processor(); - result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0; + result = SCHED(thread_should_yield)(myprocessor, current_thread()); enable_preemption(); return (result); @@ -154,14 +151,14 @@ swtch( static void swtch_pri_continue(void) { - register processor_t myprocessor; - boolean_t result; + processor_t myprocessor; + boolean_t result; thread_depress_abort_internal(current_thread()); - disable_preemption(); + disable_preemption(); myprocessor = current_processor(); - result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0; + result = SCHED(thread_should_yield)(myprocessor, current_thread()); mp_enable_preemption(); thread_syscall_return(result); @@ -172,12 +169,12 @@ boolean_t swtch_pri( __unused struct swtch_pri_args *args) { - register processor_t myprocessor; + processor_t myprocessor; boolean_t result; disable_preemption(); myprocessor = current_processor(); - if (SCHED(processor_queue_empty)(myprocessor) && rt_runq.count == 0) { + if (!SCHED(thread_should_yield)(myprocessor, current_thread())) { mp_enable_preemption(); return (FALSE); @@ -194,44 +191,30 @@ __unused struct swtch_pri_args *args) disable_preemption(); myprocessor = current_processor(); - result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0; + result = SCHED(thread_should_yield)(myprocessor, current_thread()); enable_preemption(); return (result); } -static int +static boolean_t thread_switch_disable_workqueue_sched_callback(void) { sched_call_t callback = workqueue_get_sched_callback(); - thread_t self = current_thread(); - if (!callback || self->sched_call != callback) { - return FALSE; - } - spl_t s = splsched(); - thread_lock(self); - thread_sched_call(self, NULL); - thread_unlock(self); - splx(s); - return TRUE; + return thread_disable_sched_call(current_thread(), callback) != NULL; } static void thread_switch_enable_workqueue_sched_callback(void) { sched_call_t callback = workqueue_get_sched_callback(); - thread_t self = current_thread(); - spl_t s = splsched(); - thread_lock(self); - thread_sched_call(self, callback); - thread_unlock(self); - splx(s); + thread_reenable_sched_call(current_thread(), callback); } static void thread_switch_continue(void) { - register thread_t self = current_thread(); + thread_t self = current_thread(); int option = self->saved.swtch.option; boolean_t reenable_workq_callback = self->saved.swtch.reenable_workq_callback; @@ -255,7 +238,8 @@ kern_return_t thread_switch( struct thread_switch_args *args) { - register thread_t thread, self = current_thread(); + thread_t thread = THREAD_NULL; + thread_t self = current_thread(); mach_port_name_t thread_name = args->thread_name; int option = args->option; mach_msg_timeout_t option_time = args->option_time; @@ -303,11 +287,11 @@ thread_switch( /* * Translate the port name if supplied. */ - if (thread_name != MACH_PORT_NULL) { - ipc_port_t port; + if (thread_name != MACH_PORT_NULL) { + ipc_port_t port; if (ipc_port_translate_send(self->task->itk_space, - thread_name, &port) == KERN_SUCCESS) { + thread_name, &port) == KERN_SUCCESS) { ip_reference(port); ip_unlock(port); @@ -315,16 +299,11 @@ thread_switch( ip_release(port); if (thread == self) { - (void)thread_deallocate_internal(thread); + thread_deallocate(thread); thread = THREAD_NULL; } } - else - thread = THREAD_NULL; } - else - thread = THREAD_NULL; - if (option == SWITCH_OPTION_OSLOCK_DEPRESS || option == SWITCH_OPTION_OSLOCK_WAIT) { if (thread != THREAD_NULL) { @@ -336,16 +315,18 @@ thread_switch( * a thread in another task) */ - (void)thread_deallocate_internal(thread); + thread_deallocate(thread); thread = THREAD_NULL; } else { /* * Attempt to kick the lock owner up to our same IO throttling tier. * If the thread is currently blocked in throttle_lowpri_io(), * it will immediately break out. + * + * TODO: SFI break out? */ int new_policy = proc_get_effective_thread_policy(self, TASK_POLICY_IO); - + set_thread_iotier_override(thread, new_policy); } } @@ -355,59 +336,43 @@ thread_switch( * Try to handoff if supplied. */ if (thread != THREAD_NULL) { - processor_t processor; - spl_t s; - - s = splsched(); - thread_lock(thread); - - /* - * Check that the thread is not bound - * to a different processor, and that realtime - * is not involved. - * - * Next, pull it off its run queue. If it - * doesn't come, it's not eligible. - */ - processor = current_processor(); - if (processor->current_pri < BASEPRI_RTQUEUES && - thread->sched_pri < BASEPRI_RTQUEUES && - (thread->bound_processor == PROCESSOR_NULL || - thread->bound_processor == processor) && - thread_run_queue_remove(thread) ) { - /* - * Hah, got it!! - */ - thread_unlock(thread); - - (void)thread_deallocate_internal(thread); + spl_t s = splsched(); + + /* This may return a different thread if the target is pushing on something */ + thread_t pulled_thread = thread_run_queue_remove_for_handoff(thread); + + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_THREAD_SWITCH)|DBG_FUNC_NONE, + thread_tid(thread), thread->state, + pulled_thread ? TRUE : FALSE, 0, 0); + + if (pulled_thread != THREAD_NULL) { + /* We can't be dropping the last ref here */ + thread_deallocate_safe(thread); if (wait_option) assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, - option_time, scale_factor); - else - if (depress_option) + option_time, scale_factor); + else if (depress_option) thread_depress_ms(option_time); self->saved.swtch.option = option; self->saved.swtch.reenable_workq_callback = reenable_workq_callback; - thread_run(self, (thread_continue_t)thread_switch_continue, NULL, thread); + thread_run(self, (thread_continue_t)thread_switch_continue, NULL, pulled_thread); /* NOTREACHED */ + panic("returned from thread_run!"); } - thread_unlock(thread); splx(s); thread_deallocate(thread); } - + if (wait_option) assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, scale_factor); - else - if (depress_option) + else if (depress_option) thread_depress_ms(option_time); - + self->saved.swtch.option = option; self->saved.swtch.reenable_workq_callback = reenable_workq_callback; @@ -422,6 +387,88 @@ thread_switch( return (KERN_SUCCESS); } +/* Returns a +1 thread reference */ +thread_t +port_name_to_thread_for_ulock(mach_port_name_t thread_name) +{ + thread_t thread = THREAD_NULL; + thread_t self = current_thread(); + + /* + * Translate the port name if supplied. + */ + if (thread_name != MACH_PORT_NULL) { + ipc_port_t port; + + if (ipc_port_translate_send(self->task->itk_space, + thread_name, &port) == KERN_SUCCESS) { + ip_reference(port); + ip_unlock(port); + + thread = convert_port_to_thread(port); + ip_release(port); + + if (thread == THREAD_NULL) { + return thread; + } + + if ((thread == self) || (thread->task != self->task)) { + thread_deallocate(thread); + thread = THREAD_NULL; + } + } + } + + return thread; +} + +/* This function is called after an assert_wait(), therefore it must not + * cause another wait until after the thread_run() or thread_block() + * + * Consumes a ref on thread + */ +wait_result_t +thread_handoff(thread_t thread) +{ + thread_t deallocate_thread = THREAD_NULL; + thread_t self = current_thread(); + + /* + * Try to handoff if supplied. + */ + if (thread != THREAD_NULL) { + spl_t s = splsched(); + + thread_t pulled_thread = thread_run_queue_remove_for_handoff(thread); + + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_THREAD_SWITCH)|DBG_FUNC_NONE, + thread_tid(thread), thread->state, + pulled_thread ? TRUE : FALSE, 0, 0); + + if (pulled_thread != THREAD_NULL) { + /* We can't be dropping the last ref here */ + thread_deallocate_safe(thread); + + int result = thread_run(self, THREAD_CONTINUE_NULL, NULL, pulled_thread); + + splx(s); + return result; + } + + splx(s); + + deallocate_thread = thread; + thread = THREAD_NULL; + } + + int result = thread_block(THREAD_CONTINUE_NULL); + if (deallocate_thread != THREAD_NULL) { + thread_deallocate(deallocate_thread); + } + + return result; +} + /* * Depress thread's priority to lowest possible for the specified interval, * with a value of zero resulting in no timeout being scheduled. @@ -430,7 +477,7 @@ void thread_depress_abstime( uint64_t interval) { - register thread_t self = current_thread(); + thread_t self = current_thread(); uint64_t deadline; spl_t s; @@ -440,7 +487,16 @@ thread_depress_abstime( processor_t myprocessor = self->last_processor; self->sched_pri = DEPRESSPRI; + + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY), + (uintptr_t)thread_tid(self), + self->base_pri, + self->sched_pri, + 0, /* eventually, 'reason' */ + 0); + myprocessor->current_pri = self->sched_pri; + myprocessor->current_perfctl_class = thread_get_perfcontrol_class(self); self->sched_flags |= TH_SFLAG_DEPRESS; if (interval != 0) { @@ -479,7 +535,7 @@ thread_depress_expire( thread_lock(thread); if (--thread->depress_timer_active == 0) { thread->sched_flags &= ~TH_SFLAG_DEPRESSED_MASK; - SCHED(compute_priority)(thread, FALSE); + thread_recompute_sched_pri(thread, FALSE); } thread_unlock(thread); splx(s); @@ -500,7 +556,7 @@ thread_depress_abort_internal( if (!(thread->sched_flags & TH_SFLAG_POLLDEPRESS)) { if (thread->sched_flags & TH_SFLAG_DEPRESSED_MASK) { thread->sched_flags &= ~TH_SFLAG_DEPRESSED_MASK; - SCHED(compute_priority)(thread, FALSE); + thread_recompute_sched_pri(thread, FALSE); result = KERN_SUCCESS; } @@ -535,7 +591,16 @@ thread_poll_yield( thread_lock(self); if (!(self->sched_flags & TH_SFLAG_DEPRESSED_MASK)) { self->sched_pri = DEPRESSPRI; + + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY), + (uintptr_t)thread_tid(self), + self->base_pri, + self->sched_pri, + 0, /* eventually, 'reason' */ + 0); + myprocessor->current_pri = self->sched_pri; + myprocessor->current_perfctl_class = thread_get_perfcontrol_class(self); } self->computation_epoch = abstime; self->computation_metered = 0; @@ -544,10 +609,11 @@ thread_poll_yield( abstime += (total_computation >> sched_poll_yield_shift); if (!timer_call_enter(&self->depress_timer, abstime, TIMER_CALL_USER_CRITICAL)) self->depress_timer_active++; - thread_unlock(self); - if ((preempt = csw_check(myprocessor)) != AST_NONE) + if ((preempt = csw_check(myprocessor, AST_NONE)) != AST_NONE) ast_on(preempt); + + thread_unlock(self); } } splx(s); @@ -562,7 +628,7 @@ thread_yield_internal( disable_preemption(); myprocessor = current_processor(); - if (SCHED(processor_queue_empty)(myprocessor) && rt_runq.count == 0) { + if (!SCHED(thread_should_yield)(myprocessor, current_thread())) { mp_enable_preemption(); return; @@ -576,3 +642,40 @@ thread_yield_internal( thread_depress_abort_internal(current_thread()); } +/* + * This yields to a possible non-urgent preemption pending on the current processor. + * + * This is useful when doing a long computation in the kernel without returning to userspace. + * + * As opposed to other yielding mechanisms, this does not drop the priority of the current thread. + */ +void +thread_yield_to_preemption() +{ + /* + * ast_pending() should ideally be called with interrupts disabled, but + * the check here is fine because csw_check() will do the right thing. + */ + ast_t *pending_ast = ast_pending(); + ast_t ast = AST_NONE; + processor_t p; + + if (*pending_ast & AST_PREEMPT) { + thread_t self = current_thread(); + + spl_t s = splsched(); + + p = current_processor(); + thread_lock(self); + ast = csw_check(p, AST_YIELD); + ast_on(ast); + thread_unlock(self); + + if (ast != AST_NONE) { + (void)thread_block_reason(THREAD_CONTINUE_NULL, NULL, ast); + } + + splx(s); + } +} +