diff options
| -rw-r--r-- | arch/x86/Kconfig | 1 | ||||
| -rw-r--r-- | include/linux/sched.h | 3 | ||||
| -rw-r--r-- | kernel/Kconfig.preempt | 12 | ||||
| -rw-r--r-- | kernel/entry/common.c | 14 | ||||
| -rw-r--r-- | kernel/signal.c | 40 |
5 files changed, 69 insertions, 1 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 9f5bd41bf660..d557ac29b6cd 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -120,6 +120,7 @@ config X86 select ARCH_WANTS_NO_INSTR select ARCH_WANT_HUGE_PMD_SHARE select ARCH_WANT_LD_ORPHAN_WARN + select ARCH_WANTS_RT_DELAYED_SIGNALS select ARCH_WANTS_THP_SWAP if X86_64 select ARCH_HAS_PARANOID_L1D_FLUSH select BUILDTIME_TABLE_SORT diff --git a/include/linux/sched.h b/include/linux/sched.h index 75ba8aa60248..098e37fd770a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1087,6 +1087,9 @@ struct task_struct { /* Restored if set_restore_sigmask() was used: */ sigset_t saved_sigmask; struct sigpending pending; +#ifdef CONFIG_RT_DELAYED_SIGNALS + struct kernel_siginfo forced_info; +#endif unsigned long sas_ss_sp; size_t sas_ss_size; unsigned int sas_ss_flags; diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index ce77f0265660..5644abd5f8a8 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -132,4 +132,14 @@ config SCHED_CORE which is the likely usage by Linux distributions, there should be no measurable impact on performance. - +config ARCH_WANTS_RT_DELAYED_SIGNALS + bool + help + This option is selected by architectures where raising signals + can happen in atomic contexts on PREEMPT_RT enabled kernels. This + option delays raising the signal until the return to user space + loop where it is also delivered. X86 requires this to deliver + signals from trap handlers which run on IST stacks. + +config RT_DELAYED_SIGNALS + def_bool PREEMPT_RT && ARCH_WANTS_RT_DELAYED_SIGNALS diff --git a/kernel/entry/common.c b/kernel/entry/common.c index bad713684c2e..0543a2c92f20 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -148,6 +148,18 @@ static void handle_signal_work(struct pt_regs *regs, unsigned long ti_work) arch_do_signal_or_restart(regs, ti_work & _TIF_SIGPENDING); } +#ifdef CONFIG_RT_DELAYED_SIGNALS +static inline void raise_delayed_signal(void) +{ + if (unlikely(current->forced_info.si_signo)) { + force_sig_info(¤t->forced_info); + current->forced_info.si_signo = 0; + } +} +#else +static inline void raise_delayed_signal(void) { } +#endif + static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, unsigned long ti_work) { @@ -162,6 +174,8 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, if (ti_work & _TIF_NEED_RESCHED) schedule(); + raise_delayed_signal(); + if (ti_work & _TIF_UPROBE) uprobe_notify_resume(regs); diff --git a/kernel/signal.c b/kernel/signal.c index 9b04631acde8..e93de6daa188 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1308,6 +1308,43 @@ enum sig_handler { }; /* + * On some archictectures, PREEMPT_RT has to delay sending a signal from a + * trap since it cannot enable preemption, and the signal code's + * spin_locks turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME + * which will send the signal on exit of the trap. + */ +#ifdef CONFIG_RT_DELAYED_SIGNALS +static inline bool force_sig_delayed(struct kernel_siginfo *info, + struct task_struct *t) +{ + if (!in_atomic()) + return false; + + if (WARN_ON_ONCE(t->forced_info.si_signo)) + return true; + + if (is_si_special(info)) { + WARN_ON_ONCE(info != SEND_SIG_PRIV); + t->forced_info.si_signo = info->si_signo; + t->forced_info.si_errno = 0; + t->forced_info.si_code = SI_KERNEL; + t->forced_info.si_pid = 0; + t->forced_info.si_uid = 0; + } else { + t->forced_info = *info; + } + set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); + return true; +} +#else +static inline bool force_sig_delayed(struct kernel_siginfo *info, + struct task_struct *t) +{ + return false; +} +#endif + +/* * Force a signal that the process can't ignore: if necessary * we unblock the signal and change any SIG_IGN to SIG_DFL. * @@ -1327,6 +1364,9 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, struct k_sigaction *action; int sig = info->si_signo; + if (force_sig_delayed(info, t)) + return 0; + spin_lock_irqsave(&t->sighand->siglock, flags); action = &t->sighand->action[sig-1]; ignored = action->sa.sa_handler == SIG_IGN; |