Draft: start lab 3

kernel/include/utils.h

@@ -36,3 +36,15 @@ void exit(int);
   (ptr = (orig_type*)((bump_type*)ptr + 1)), \
   ((bump_type*)ptr - 1) \
 )
+
+#define R_SYSREG(ret, reg) \
+  asm volatile( \
+    "mrs %[a], " #reg \
+    : [a] "=r" (ret) \
+  )
+
+#define W_SYSREG(val, reg) \
+  asm volatile( \
+    "msr " #reg ", %[a]" \
+    : [a] "r" (val) \
+  )