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 <[email protected]>
  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:
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