Bring back LX zones.

*** 1158,1167 ****
--- 1158,1209 ----
          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.
   */