Bring back LX zones.

@@ -1158,10 +1158,52 @@
         SET_SIZE(_sys_sysenter_post_swapgs)
         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 other entry points, 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)
+        SWAPGS                          /* kernel gsbase */
+        XPV_TRAP_POP
+        BRAND_CALLBACK(BRAND_CB_INT80, BRAND_URET_FROM_INTR_STACK())
+        SWAPGS                          /* user gsbase */
+        jmp     nopop_int80
+
+        ENTRY_NP(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 %rip to point before the INT, push the expected error
+         * code and fake a GP fault. Note on 64-bit hypervisor we need
+         * to undo the XPV_TRAP_POP and push rcx and r11 back on the stack
+         * because gptrap will pop them again with its own XPV_TRAP_POP.
+         */
+        XPV_TRAP_POP
+nopop_int80:
+        subq    $2, (%rsp)      /* int insn 2-bytes */
+        pushq   $_CONST(_MUL(T_INT80, GATE_DESC_SIZE) + 2)
+#if defined(__xpv)
+        push    %r11
+        push    %rcx
+#endif
+        jmp     gptrap                  / GP fault
+        SET_SIZE(sys_int80)
+        SET_SIZE(brand_sys_int80)
+#endif  /* __lint */
+
+
 /*
  * This is the destination of the "int $T_SYSCALLINT" interrupt gate, used by
  * the generic i386 libc to do system calls. We do a small amount of setup
  * before jumping into the existing sys_syscall32 path.
  */