[kernel] Add userspace threading

Implement the syscalls necessary for threads to create other threads in
their same process. This involved rearranging a number of syscalls, as
well as implementing object_wait and a basic implementation of a
process' list of handles.

src/drivers/nulldrv/main.cpp

@@ -3,32 +3,53 @@
 
 #include "j6/types.h"
 #include "j6/errors.h"
+#include "j6/signals.h"
 
 extern "C" {
-	j6_status_t get_process_koid(j6_koid_t *koid);
-	j6_status_t sleep(uint64_t til);
-	j6_status_t debug();
-	j6_status_t message(const char *msg);
+	j6_status_t system_log(const char *msg);
+
+	j6_status_t object_wait(j6_handle_t obj, j6_signal_t sig, j6_signal_t *out);
+
+	j6_status_t process_koid(j6_koid_t *koid);
+
+	j6_status_t thread_koid(j6_koid_t *koid);
+	j6_status_t thread_create(void (*koid)(), j6_handle_t *handle);
+	j6_status_t thread_sleep(uint64_t til);
+	j6_status_t thread_exit(int64_t status);
 
 	int main(int, const char **);
 }
 
+void
+thread_proc()
+{
+	system_log("sub thread starting");
+	for (int i = 1; i < 5; ++i)
+		thread_sleep(i*10);
+
+	system_log("sub thread exiting");
+	thread_exit(0);
+}
 
 int
 main(int argc, const char **argv)
 {
-	uint64_t pid = 0;
-	uint64_t child = 0;
-	j6_koid_t process = 0;
+	j6_handle_t child = 0;
+	j6_signal_t out = 0;
 
-	j6_status_t result = get_process_koid(&process);
+	system_log("main thread starting");
+
+	j6_status_t result = thread_create(&thread_proc, &child);
 	if (result != j6_status_ok)
 		return result;
 
-	message("hello from nulldrv!");
+	system_log("main thread waiting on child");
 
-	for (int i = 1; i < 5; ++i)
-		sleep(i*10);
+	result = object_wait(child, -1ull, &out);
+	if (result != j6_status_ok)
+		return result;
 
-	return pid;
+	system_log("main thread done, exiting");
+	return 0;
 }
+

src/drivers/nulldrv/main.s

@@ -6,52 +6,30 @@ extern main
 extern exit
 
 section .text
-global get_process_koid
-get_process_koid:
-	push rbp
-	mov rbp, rsp
 
-	; address of out var should already be in rdi
-	mov rax, 0x10  ; getpid syscall
-	syscall        ; result is now already in rax, so just return
+%macro SYSCALL 2
+	global %1
+	%1:
+		push rbp
+		mov rbp, rsp
 
-	pop rbp
-	ret
+		; address of args should already be in rdi, etc
+		mov rax, %2
+		syscall
+		; result is now already in rax, so just return
 
-global debug
-debug:
-	push rbp
-	mov rbp, rsp
-
-	mov rax, 0x00  ; debug syscall
-	syscall
-
-	pop rbp
-	ret
-
-global sleep
-sleep:
-	push rbp
-	mov rbp, rsp
-
-	mov rax, 0x14  ; sleep syscall
-	syscall
-
-	pop rbp
-	ret
-
-global message
-message:
-	push rbp
-	mov rbp, rsp
-
-	; message should already be in rdi
-	mov rax, 0x12
-	syscall
-
-	pop rbp
-	ret
+		pop rbp
+		ret
+%endmacro
 
+SYSCALL system_log, 0x00
+SYSCALL object_wait, 0x09
+SYSCALL process_koid, 0x10
+SYSCALL thread_koid, 0x18
+SYSCALL thread_create, 0x19
+SYSCALL thread_exit, 0x1a
+SYSCALL thread_pause, 0x1b
+SYSCALL thread_sleep, 0x1c
 
 global _start
 _start: