svn commit: r255906 - stable/8/sys/amd64/amd64

[Konstantin Belousov]

Author: kib
Date: Fri Sep 27 07:02:48 2013
New Revision: 255906
URL: http://svnweb.freebsd.org/changeset/base/255906

Log:
  MFC r255844:
  Ensure that the ERESTART return from the syscall reloads the registers,
  to make the restarted syscall instruction pass the correct arguments.
  
  PR:	kern/182161

Modified:
  stable/8/sys/amd64/amd64/vm_machdep.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/   (props changed)

Modified: stable/8/sys/amd64/amd64/vm_machdep.c
==============================================================================
--- stable/8/sys/amd64/amd64/vm_machdep.c	Fri Sep 27 06:56:58 2013	(r255905)
+++ stable/8/sys/amd64/amd64/vm_machdep.c	Fri Sep 27 07:02:48 2013	(r255906)
@@ -395,9 +395,13 @@ cpu_set_syscall_retval(struct thread *td
 		 * for the next iteration.
 		 * %r10 restore is only required for freebsd/amd64 processes,
 		 * but shall be innocent for any ia32 ABI.
+		 *
+		 * Require full context restore to get the arguments
+		 * in the registers reloaded at return to usermode.
 		 */
 		td->td_frame->tf_rip -= td->td_frame->tf_err;
 		td->td_frame->tf_r10 = td->td_frame->tf_rcx;
+		set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
 		break;
 
 	case EJUSTRETURN: