git: vkernel - Fix FP corruption from preemptive thread switch

[Matthew Dillon]

commit eaaa6d6031b7b67f3b067023af0d99386a1d6d9b
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Fri Oct 2 15:53:17 2009 -0700

    vkernel - Fix FP corruption from preemptive thread switch
    
    * Recent work on the vkernel enabled preemptive interrupt thread switching.
      This introduced a race where the floating point state could change
      out from under the vkernel's go_user() function, causing the FP state
      in the virtual user process to become corrupt.
    
    * Fixed by introducing a critical section which essentially defers any
      preemptive thread switches inside go_user().
    
    Reported-by: YONETANI Tomokazu <qhwt+dfly at les.ath.cx>
    Test-cases-by: YONETANI Tomokazu <qhwt+dfly at les.ath.cx>

Summary of changes:
 sys/platform/vkernel/i386/trap.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/eaaa6d6031b7b67f3b067023af0d99386a1d6d9b


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