• O
    x86/fpu: Introduce restore_init_xstate() · 8f4d8186
    Oleg Nesterov 提交于
    Extract the "use_eager_fpu()" code from drop_init_fpu() into a new,
    simple helper restore_init_xstate(). The next patch adds another user.
    
    - It is not clear why we do not check use_fxsr() like fpu_restore_checking()
      does. eager_fpu_init_bp() calls setup_init_fpu_buf() too, and we have the
      "eagerfpu=on" kernel option.
    
    - Ignoring the fact that init_xstate_buf is "struct xsave_struct *", not
      "union thread_xstate *", it is not clear why we can not simply use
      fpu_restore_checking() and avoid the code duplication.
    
    - It is not clear why we can't call setup_init_fpu_buf() unconditionally
      to always create init_xstate_buf(). Then do_device_not_available() path
      (at least) could use restore_init_xstate() too. It doesn't need to init
      fpu->state, its content doesn't matter until unlazy_fpu()/__switch_to()/etc
      which overwrites this memory anyway.
    Signed-off-by: NOleg Nesterov <oleg@redhat.com>
    Signed-off-by: NBorislav Petkov <bp@suse.de>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Pekka Riikonen <priikone@iki.fi>
    Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Suresh Siddha <sbsiddha@gmail.com>
    Link: http://lkml.kernel.org/r/20150311173429.GD5032@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
    8f4d8186
fpu-internal.h 15.9 KB