diff options
Diffstat (limited to 'arch/x86/kernel/process.h')
-rw-r--r-- | arch/x86/kernel/process.h | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/arch/x86/kernel/process.h b/arch/x86/kernel/process.h new file mode 100644 index 000000000..76b547b83 --- /dev/null +++ b/arch/x86/kernel/process.h @@ -0,0 +1,39 @@ +/* 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); +} |