svn commit: r255844 - head/sys/amd64/amd64

[Konstantin Belousov]

Author: kib
Date: Tue Sep 24 12:24:48 2013
New Revision: 255844
URL: http://svnweb.freebsd.org/changeset/base/255844

Log:
  Ensure that the ERESTART return from the syscall reloads the
  registers, to make the restarted syscall instruction pass the correct
  arguments.
  
  PR:	kern/182161
  Reported by:	Russ Cox <rsc at swtch.com>
  Sponsored by:	The FreeBSD Foundation
  MFC after:	3 days
  Approved by:	re (marius)

Modified:
  head/sys/amd64/amd64/vm_machdep.c

Modified: head/sys/amd64/amd64/vm_machdep.c
==============================================================================
--- head/sys/amd64/amd64/vm_machdep.c	Tue Sep 24 11:49:04 2013	(r255843)
+++ head/sys/amd64/amd64/vm_machdep.c	Tue Sep 24 12:24:48 2013	(r255844)
@@ -400,9 +400,13 @@ 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: