Bring back LX zones.

@@ -629,10 +629,40 @@
         popl    %ecx                    / sysexit: %ecx -> %esp
         sti
         sysexit
         SET_SIZE(sys_sysenter)
         SET_SIZE(brand_sys_sysenter)
+#endif  /* __lint */
+
+#if defined(__lint)
+/*
+ * System call via an int80.  This entry point is only used by the Linux
+ * application environment.  Unlike the sysenter path, there is no default
+ * action to take if no callback is registered for this process.
+ */
+void
+sys_int80()
+{}
+
+#else   /* __lint */
+
+        ENTRY_NP(brand_sys_int80)
+        BRAND_CALLBACK(BRAND_CB_INT80)
+
+        ALTENTRY(sys_int80)
+        /*
+         * We hit an int80, but this process isn't of a brand with an int80
+         * handler.  Bad process!  Make it look as if the INT failed.
+         * Modify %eip to point before the INT, push the expected error
+         * code and fake a GP fault.
+         * 
+         */
+        subl    $2, (%esp)      /* int insn 2-bytes */
+        pushl   $_CONST(_MUL(T_INT80, GATE_DESC_SIZE) + 2)
+        jmp     gptrap                  / GP fault
+        SET_SIZE(sys_int80)
+        SET_SIZE(brand_sys_int80)
 
 /*
  * Declare a uintptr_t which covers the entire pc range of syscall
  * handlers for the stack walkers that need this.
  */