• Chris Lalancette's avatar
    x86: Make sure get_user_desc() doesn't sign extend. · 2c75910f
    Chris Lalancette authored
    The current implementation of get_user_desc() sign extends the return
    value because of integer promotion rules.  For the most part, this
    doesn't matter, because the top bit of base2 is usually 0.  If, however,
    that bit is 1, then the entire value will be 0xffff...  which is
    probably not what the caller intended.
    
    This patch casts the entire thing to unsigned before returning, which
    generates almost the same assembly as the current code but replaces the
    final "cltq" (sign extend) with a "mov %eax %eax" (zero-extend).  This
    fixes booting certain guests under KVM.
    Signed-off-by: default avatarChris Lalancette <clalance@redhat.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    2c75910f
desc.h 9.85 KB