Add sys_hello and testbin/hellotest

`sys_hello` is a new syscall that just prints some text in the terminal.

`testbin/hellotest` is a userland binary that just calls `sys_hello`

kern/arch/mips/syscall/syscall.c

@@ -104,6 +104,9 @@ void syscall(struct trapframe *tf) {
   case SYS___time:
     err = sys___time((userptr_t)tf->tf_a0, (userptr_t)tf->tf_a1);
     break;
+  case SYS_hello:
+    err = sys_hello();
+    break;
 
   case SYS__exit:
     err = 0;

kern/conf/conf.kern

@@ -379,6 +379,7 @@ file      vfs/devnull.c
 file      syscall/loadelf.c
 file      syscall/runprogram.c
 file      syscall/time_syscalls.c
+file      syscall/hello.c
 
 #
 # Startup and initialization

kern/include/kern/syscall.h

@@ -94,6 +94,7 @@
 // #define SYS_getpriority 38
 // #define SYS_setpriority 39
 //                               (process groups, sessions, and job control)
+#define SYS_hello 41
 // #define SYS_getpgid    40
 // #define SYS_setpgid    41
 // #define SYS_getsid     42

kern/include/syscall.h

@@ -57,4 +57,6 @@ __DEAD void enter_new_process(int argc, userptr_t argv, userptr_t env,
 int sys_reboot(int code);
 int sys___time(userptr_t user_seconds, userptr_t user_nanoseconds);
 
+int sys_hello(void);
+
 #endif /* _SYSCALL_H_ */

kern/syscall/hello.c

@@ -0,0 +1,7 @@
+#include <types.h>
+#include <lib.h>
+#include <syscall.h>
+int sys_hello(void) {
+  kprintf("Hello CSE4001!\n");
+  return 0;
+}

userland/include/unistd.h

@@ -156,4 +156,6 @@ int execvp(const char *prog, char *const *args); /* calls execv */
 char *getcwd(char *buf, size_t buflen);          /* calls __getcwd */
 time_t time(time_t *seconds);                    /* calls __time */
 
+int hello(void);
+
 #endif /* _UNISTD_H_ */

userland/testbin/Makefile

@@ -7,7 +7,7 @@ TOP=../..
 
 SUBDIRS=add argtest badcall bigexec bigfile bigfork bigseek bloat conman \
 	crash ctest dirconc dirseek dirtest f_test factorial farm faulter \
-	filetest forkbomb forktest frack hash hog huge \
+	filetest forkbomb forktest frack hash hellotest hog huge \
 	malloctest matmult multiexec palin parallelvm poisondisk psort \
 	randcall redirect rmdirtest rmtest \
 	sbrktest schedpong sort sparsefile tail tictac triplehuge \

userland/testbin/hellotest/Makefile

@@ -0,0 +1,11 @@
+# Makefile for hello
+
+TOP=../../..
+.include "$(TOP)/mk/os161.config.mk"
+
+PROG=hellotest
+SRCS=hello.c
+BINDIR=/testbin
+
+.include "$(TOP)/mk/os161.prog.mk"
+

userland/testbin/hellotest/hello.c

@@ -0,0 +1,8 @@
+#include <unistd.h>
+
+extern int hello(void);
+
+int main() {
+  hello();
+  return 0;
+}