Fix syscall in thinpad.

kernel/src/arch/mipsel/context.rs

@@ -133,6 +133,37 @@ impl Debug for TrapFrame {
             .field("epc", &self.epc)
             .field("cause", &self.cause.bits)
             .field("vaddr", &self.vaddr)
+            .field("at", &self.at)
+            .field("v0", &self.v0)
+            .field("v1", &self.v1)
+            .field("a0", &self.a0)
+            .field("a1", &self.a1)
+            .field("a2", &self.a2)
+            .field("a3", &self.a3)
+            .field("t0", &self.t0)
+            .field("t1", &self.t1)
+            .field("t2", &self.t2)
+            .field("t3", &self.t3)
+            .field("t4", &self.t4)
+            .field("t5", &self.t5)
+            .field("t6", &self.t6)
+            .field("t7", &self.t7)
+            .field("s0", &self.s0)
+            .field("s1", &self.s1)
+            .field("s2", &self.s2)
+            .field("s3", &self.s3)
+            .field("s4", &self.s4)
+            .field("s5", &self.s5)
+            .field("s6", &self.s6)
+            .field("s7", &self.s7)
+            .field("t8", &self.t8)
+            .field("t9", &self.t9)
+            .field("k0", &self.k0)
+            .field("k1", &self.k1)
+            .field("gp", &self.gp)
+            .field("sp", &self.sp)
+            .field("fp", &self.fp)
+            .field("ra", &self.ra)
             .finish()
     }
 }

kernel/src/arch/mipsel/interrupt.rs

@@ -154,7 +154,14 @@ fn timer() {
 fn syscall(tf: &mut TrapFrame) {
     tf.epc += 4; // Must before syscall, because of fork.
     let arguments = [tf.a0, tf.a1, tf.a2, tf.a3, tf.t0, tf.t1];
-    trace!("MIPS syscall {} invoked with {:?}", tf.v0, arguments);
+    trace!("MIPS syscall {} invoked with {:x?}, epc = {:x?}", tf.v0, arguments, tf.epc);
+
+
+    // temporary solution for ThinPad
+    if(tf.v0 == 0) {
+        warn!("Syscall ID = 0");
+        tf.v0 = unsafe { *((tf.sp + 28) as *const usize) };
+    }
 
     let ret = crate::syscall::syscall(tf.v0, arguments, tf) as isize;
     // comply with mips n32 abi, always return a positive value