40 lines
1.1 KiB
C
40 lines
1.1 KiB
C
|
/* SPDX-License-Identifier: GPL-2.0 */
|
||
|
|
//
|
||
|
|
// Code shared between 32 and 64 bit
|
||
|
|
|
||
|
|
#include <asm/spec-ctrl.h>
|
||
|
|
|
||
|
|
void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This needs to be inline to optimize for the common case where no extra
|
||
|
|
* work needs to be done.
|
||
|
|
*/
|
||
|
|
static inline void switch_to_extra(struct task_struct *prev,
|
||
|
|
struct task_struct *next)
|
||
|
|
{
|
||
|
|
unsigned long next_tif = read_task_thread_flags(next);
|
||
|
|
unsigned long prev_tif = read_task_thread_flags(prev);
|
||
|
|
|
||
|
|
if (IS_ENABLED(CONFIG_SMP)) {
|
||
|
|
/*
|
||
|
|
* Avoid __switch_to_xtra() invocation when conditional
|
||
|
|
* STIBP is disabled and the only different bit is
|
||
|
|
* TIF_SPEC_IB. For CONFIG_SMP=n TIF_SPEC_IB is not
|
||
|
|
* in the TIF_WORK_CTXSW masks.
|
||
|
|
*/
|
||
|
|
if (!static_branch_likely(&switch_to_cond_stibp)) {
|
||
|
|
prev_tif &= ~_TIF_SPEC_IB;
|
||
|
|
next_tif &= ~_TIF_SPEC_IB;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* __switch_to_xtra() handles debug registers, i/o bitmaps,
|
||
|
|
* speculation mitigations etc.
|
||
|
|
*/
|
||
|
|
if (unlikely(next_tif & _TIF_WORK_CTXSW_NEXT ||
|
||
|
|
prev_tif & _TIF_WORK_CTXSW_PREV))
|
||
|
|
__switch_to_xtra(prev, next);
|
||
|
|
}
|