Draft: lab 5 failed

userprog/lib/syscall.S

@@ -0,0 +1,13 @@
+.global syscall
+syscall:
+	mov x8, x0
+	mov x0, x1
+	mov x1, x2
+	mov x2, x3
+	mov x3, x4
+	mov x4, x5
+	mov x5, x6
+	mov x6, x7
+
+	svc 0
+	ret

userprog/lib/syscall.c

@@ -0,0 +1,25 @@
+#include <syscall.h>
+
+int32_t getpid()
+{ return (int32_t)syscall(0); }
+
+size_t uart_read(char buf[], size_t size)
+{ return (size_t)syscall(1, buf, size); }
+
+size_t uart_write(const char buf[], size_t size)
+{ return (size_t)syscall(2, buf, size); }
+
+int32_t exec(const char *name, char *const argv[])
+{ return (int32_t)syscall(3, name, argv); }
+
+int32_t fork(void)
+{ return (int32_t)syscall(4); }
+
+void exit(int32_t status)
+{ syscall(5); __builtin_unreachable(); }
+
+int32_t mbox_call(uint8_t ch, uint32_t *mbox)
+{ return (int32_t)syscall(6, ch, mbox); }
+
+void kill(int32_t pid)
+{ syscall(7, pid); }