Kernel: Generally improve signals

kernel/arch/x86_64/IDT.cpp

@@ -189,12 +189,22 @@ namespace IDT
 				break;
 			}
 
-			Kernel::Thread::current().handle_signal(-signal);
+			Kernel::Thread::current().handle_signal(signal);
 		}
 		else
 		{
 			Kernel::panic("Unhandled exception");
 		}
+
+		switch (Kernel::Thread::current().state())
+		{
+		case Kernel::Thread::State::Terminating:
+			ASSERT_NOT_REACHED();
+		case Kernel::Thread::State::Terminated:
+			Kernel::Scheduler::get().execute_current_thread();
+		default:
+			break;
+		}
 	}
 
 	extern "C" void cpp_irq_handler(uint64_t irq, Kernel::InterruptStack& interrupt_stack)
@@ -222,6 +232,16 @@ namespace IDT
 			InterruptController::get().eoi(irq);
 
 		Kernel::Scheduler::get().reschedule_if_idling();
+
+		switch (Kernel::Thread::current().state())
+		{
+		case Kernel::Thread::State::Terminating:
+			ASSERT_NOT_REACHED();
+		case Kernel::Thread::State::Terminated:
+			Kernel::Scheduler::get().execute_current_thread();
+		default:
+			break;
+		}
 	}
 
 	static void flush_idt()

kernel/include/kernel/Scheduler.h

@@ -30,6 +30,7 @@ namespace Kernel
 
 		static bool is_valid_tid(pid_t tid);
 
+		[[noreturn]] void execute_current_thread();
 		[[noreturn]] void delete_current_process_and_thread();
 
 	private:
@@ -39,7 +40,6 @@ namespace Kernel
 		[[nodiscard]] bool save_current_thread();
 		void remove_and_advance_current_thread();
 		void advance_current_thread();
-		[[noreturn]] void execute_current_thread();
 
 		BAN::ErrorOr<void> add_thread(Thread*);
 
@@ -75,7 +75,6 @@ namespace Kernel
 
 		uint64_t m_last_reschedule = 0;
 
-		friend class Thread;
 		friend class Process;
 	};
 

kernel/kernel/Process.cpp

@@ -418,9 +418,9 @@ namespace Kernel
 			m_userspace_info.argc = str_argv.size();
 
 			asm volatile("cli");
-			m_threads.front()->setup_exec();
 		}
 
+		m_threads.front()->setup_exec();
 		Scheduler::get().execute_current_thread();
 		ASSERT_NOT_REACHED();
 	}
@@ -867,8 +867,8 @@ namespace Kernel
 		ASSERT(this == &Process::current());
 		
 		CriticalScope _;
-		Thread::current().handle_signal(-signal);
-		ASSERT_NOT_REACHED();
+		Thread::current().handle_signal(signal);
+		return 0;
 	}
 
 	BAN::ErrorOr<long> Process::sys_tcsetpgrp(int fd, pid_t pgid)

kernel/kernel/Scheduler.cpp

@@ -86,7 +86,6 @@ namespace Kernel
 
 	void Scheduler::reschedule()
 	{
-		VERIFY_STI();
 		DISABLE_INTERRUPTS();
 
 		if (save_current_thread())
@@ -247,7 +246,7 @@ namespace Kernel
 				current->set_started();
 				start_thread(current->rsp(), current->rip());
 			case Thread::State::Executing:
-				while (current->has_signal_to_execute() && current->state() == Thread::State::Executing)
+				while (current->has_signal_to_execute())
 					current->handle_signal();
 				// fall through
 			case Thread::State::Terminating:

kernel/kernel/Syscall.cpp

@@ -1,6 +1,7 @@
 #include <kernel/Debug.h>
 #include <kernel/InterruptStack.h>
 #include <kernel/Process.h>
+#include <kernel/Scheduler.h>
 #include <kernel/Syscall.h>
 
 #include <termios.h>
@@ -172,6 +173,16 @@ namespace Kernel
 
 		asm volatile("cli");
 
+		switch (Thread::current().state())
+		{
+		case Thread::State::Terminating:
+			ASSERT_NOT_REACHED();
+		case Thread::State::Terminated:
+			Scheduler::get().execute_current_thread();
+		default:
+			break;
+		}
+
 		if (ret.is_error())
 			return -ret.error().get_error_code();
 		return ret.value();

kernel/kernel/Thread.cpp

@@ -218,7 +218,7 @@ namespace Kernel
 
 	bool Thread::has_signal_to_execute() const
 	{
-		if (!m_process || m_handling_signal)
+		if (!is_userspace() || m_handling_signal || m_state != State::Executing)
 			return false;
 		uint64_t full_pending_mask = m_signal_pending_mask | m_process->m_signal_pending_mask;
 		return full_pending_mask & ~m_signal_block_mask;
@@ -229,10 +229,14 @@ namespace Kernel
 		ASSERT(!interrupts_enabled());
 		if (m_handling_signal == 0)
 			derrorln("set_signal_done called while not handling singal");
-		if (m_handling_signal != signal)
+		else if (m_handling_signal != signal)
 			derrorln("set_signal_done called with invalid signal");
 		else
 			m_handling_signal = 0;
+
+		if (m_handling_signal == 0)
+			while (has_signal_to_execute())
+				handle_signal();
 	}
 
 	void Thread::handle_signal(int signal)
@@ -240,6 +244,7 @@ namespace Kernel
 		ASSERT(!interrupts_enabled());
 		ASSERT(&Thread::current() == this);
 		ASSERT(is_userspace());
+		ASSERT(!m_handling_signal);
 
 		if (signal == 0)
 		{
@@ -252,16 +257,10 @@ namespace Kernel
 			}
 			ASSERT(signal <= _SIGMAX);
 		}
-		else if (signal > 0)
-		{
-			uint64_t full_pending_mask = m_signal_pending_mask | process().m_signal_pending_mask;
-			uint64_t mask = 1ull << signal;
-			ASSERT(full_pending_mask & mask);
-			ASSERT(!(m_signal_block_mask & mask));
-		}
 		else
 		{
-			signal = -signal;
+			ASSERT(signal >= _SIGMIN);
+			ASSERT(signal <= _SIGMAX);
 		}
 
 		uintptr_t& return_rsp = this->return_rsp();
@@ -284,7 +283,6 @@ namespace Kernel
 			write_to_stack(return_rsp, signal);
 			write_to_stack(return_rsp, signal_handler);
 			return_rip = (uintptr_t)signal_trampoline;
-			return;
 		}
 		else
 		{