diff options
Diffstat (limited to 'include/linux/rseq.h')
| -rw-r--r-- | include/linux/rseq.h | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/include/linux/rseq.h b/include/linux/rseq.h index ded4baa34586..b5e4803c4ebe 100644 --- a/include/linux/rseq.h +++ b/include/linux/rseq.h @@ -42,7 +42,7 @@ static inline void rseq_signal_deliver(struct ksignal *ksig, struct pt_regs *reg static inline void rseq_raise_notify_resume(struct task_struct *t) { - set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); + set_tsk_thread_flag(t, TIF_RSEQ); } /* Invoked from context switch to force evaluation on exit to user */ @@ -114,17 +114,25 @@ static inline void rseq_force_update(void) /* * KVM/HYPERV invoke resume_user_mode_work() before entering guest mode, - * which clears TIF_NOTIFY_RESUME. To avoid updating user space RSEQ in - * that case just to do it eventually again before returning to user space, - * the entry resume_user_mode_work() invocation is ignored as the register - * argument is NULL. + * which clears TIF_NOTIFY_RESUME on architectures that don't use the + * generic TIF bits and therefore can't provide a separate TIF_RSEQ flag. * - * After returning from guest mode, they have to invoke this function to - * re-raise TIF_NOTIFY_RESUME if necessary. + * To avoid updating user space RSEQ in that case just to do it eventually + * again before returning to user space, because __rseq_handle_slowpath() + * does nothing when invoked with NULL register state. + * + * After returning from guest mode, before exiting to userspace, hypervisors + * must invoke this function to re-raise TIF_NOTIFY_RESUME if necessary. */ static inline void rseq_virt_userspace_exit(void) { if (current->rseq.event.sched_switch) + /* + * The generic optimization for deferring RSEQ updates until the next + * exit relies on having a dedicated TIF_RSEQ. + */ + if (!IS_ENABLED(CONFIG_HAVE_GENERIC_TIF_BITS) && + current->rseq.event.sched_switch) rseq_raise_notify_resume(current); } |