Author: kib
Date: Thu Jan 11 12:54:33 2018
New Revision: 327819
URL: https://svnweb.freebsd.org/changeset/base/327819

Log:
  Do not clear %RFLAGS.DF on fast syscall entry.
  
  Hardware already did it for us due to the mask loaded into the
  MSR_SF_MASK msr register.
  
  Reviewed by:  jhb
  Sponsored by: The FreeBSD Foundation
  MFC after:    1 week
  Differential revision:        https://reviews.freebsd.org/D13838

Modified:
  head/sys/amd64/amd64/exception.S

Modified: head/sys/amd64/amd64/exception.S
==============================================================================
--- head/sys/amd64/amd64/exception.S    Thu Jan 11 12:40:43 2018        
(r327818)
+++ head/sys/amd64/amd64/exception.S    Thu Jan 11 12:54:33 2018        
(r327819)
@@ -410,7 +410,6 @@ IDTVEC(fast_syscall)
        movq    %r14,TF_R14(%rsp)       /* C preserved */
        movq    %r15,TF_R15(%rsp)       /* C preserved */
        movl    $TF_HASSEGS,TF_FLAGS(%rsp)
-       cld
        FAKE_MCOUNT(TF_RIP(%rsp))
        movq    PCPU(CURTHREAD),%rdi
        movq    %rsp,TD_FRAME(%rdi)
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