Branch data     Line data    Source code

       1                 :            : /* SPDX-License-Identifier: GPL-2.0 */
       2                 :            : //
       3                 :            : // Code shared between 32 and 64 bit
       4                 :            : 
       5                 :            : #include <asm/spec-ctrl.h>
       6                 :            : 
       7                 :            : void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p);
       8                 :            : 
       9                 :            : /*
      10                 :            :  * This needs to be inline to optimize for the common case where no extra
      11                 :            :  * work needs to be done.
      12                 :            :  */
      13                 :     790756 : static inline void switch_to_extra(struct task_struct *prev,
      14                 :            :                                    struct task_struct *next)
      15                 :            : {
      16         [ -  + ]:     790756 :         unsigned long next_tif = task_thread_info(next)->flags;
      17                 :     790756 :         unsigned long prev_tif = task_thread_info(prev)->flags;
      18                 :            : 
      19                 :     790756 :         if (IS_ENABLED(CONFIG_SMP)) {
      20                 :            :                 /*
      21                 :            :                  * Avoid __switch_to_xtra() invocation when conditional
      22                 :            :                  * STIBP is disabled and the only different bit is
      23                 :            :                  * TIF_SPEC_IB. For CONFIG_SMP=n TIF_SPEC_IB is not
      24                 :            :                  * in the TIF_WORK_CTXSW masks.
      25                 :            :                  */
      26   [ -  +  +  - ]:     790756 :                 if (!static_branch_likely(&switch_to_cond_stibp)) {
      27                 :     790756 :                         prev_tif &= ~_TIF_SPEC_IB;
      28                 :     790756 :                         next_tif &= ~_TIF_SPEC_IB;
      29                 :            :                 }
      30                 :            :         }
      31                 :            : 
      32                 :            :         /*
      33                 :            :          * __switch_to_xtra() handles debug registers, i/o bitmaps,
      34                 :            :          * speculation mitigations etc.
      35                 :            :          */
      36   [ +  -  -  + ]:     790756 :         if (unlikely(next_tif & _TIF_WORK_CTXSW_NEXT ||
      37                 :            :                      prev_tif & _TIF_WORK_CTXSW_PREV))
      38                 :          0 :                 __switch_to_xtra(prev, next);
      39                 :     790756 : }