From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51772C43457 for ; Thu, 15 Oct 2020 13:17:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE74822268 for ; Thu, 15 Oct 2020 13:17:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="p2zoKyk3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727921AbgJONRL (ORCPT ); Thu, 15 Oct 2020 09:17:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728521AbgJONRK (ORCPT ); Thu, 15 Oct 2020 09:17:10 -0400 Received: from mail-il1-x144.google.com (mail-il1-x144.google.com [IPv6:2607:f8b0:4864:20::144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E724C0613D5 for ; Thu, 15 Oct 2020 06:17:09 -0700 (PDT) Received: by mail-il1-x144.google.com with SMTP id t12so4028562ilh.3 for ; Thu, 15 Oct 2020 06:17:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=gcXNClmvNGT0ZcZm/PYa3YKMmvRI86wf/VrdveKe5Mw=; b=p2zoKyk3R6z74d2ZY5D871Cu1F02mngcKJyOWn17rMhYy5EiMaVsG4JqN6BMDvUkyi MW1ntb2dtVwNaHwRmLvPS0Kwr6RJxASfuWcMx17kduWHnPamufK/xEzNypxHnXnTSJLU HaYMAbkZFgeqYohoFCnLvOHF+VIu7QbdFU5Im9afMOsn43+ttk5z5Sn0guB66mXR13/V Rjtarkfx0E4sHMCkBHW17HI82TKlGVXZfrQHgqS3NW5P/ez5JMITSEJDdwE/DcqOtR/4 yq6mh/+D48mxwri70hGcSPx9DHdNhge9o9jzuvZYweDGlqnw03Zo0dJmdar1wK1VqJ8T L3OA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=gcXNClmvNGT0ZcZm/PYa3YKMmvRI86wf/VrdveKe5Mw=; b=j+LpkVPVzmq1RD0zjHjGr2li2X4uO8U+Eq0V26UxU0Kl1y+F6zNKXDldws5/o6iL3o cDJn5nt5sByAtfzAHQjvdrALMBuXCw/P783qbzbCTxS8FaqYIdQq0xA/ixf3RLdWWb0K +Tb2VN7YpV+u66I7KtipvbFKjTgdfiRGVUwqKSQMzt812/uN3w7GlMWoWPSDfG5+Sv4T koFFQThCoPqN+f0UP1x7ogP4LBwEYO1H9XE0AoPNnBdQumTA1d9o6rkfLFAFnjouWVsC D9HwPmCWLmjK8W1m/MaVs+s5/GDuALdCwpVzxYECN4GzsvaHgF3pID241TJeQaFJTrS1 xLJw== X-Gm-Message-State: AOAM533xWPe+SPulJrT8ETeftdXg5bHgD/zK74YRzeGiC992XH3U3eEF JYvxFSAcbF8ZKPrxl8Thm/gu+Q== X-Google-Smtp-Source: ABdhPJxBC5rES6GTgDbiJXq/23LwRSUv6LcM0o2cMCuuEo5j5D/RP8V783dkwu/3FOnDOFdyDUoN8A== X-Received: by 2002:a05:6e02:cf:: with SMTP id r15mr885977ilq.90.1602767828325; Thu, 15 Oct 2020 06:17:08 -0700 (PDT) Received: from p1.localdomain ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id m13sm2486736ioo.9.2020.10.15.06.17.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Oct 2020 06:17:07 -0700 (PDT) From: Jens Axboe To: linux-kernel@vger.kernel.org, io-uring@vger.kernel.org Cc: peterz@infradead.org, oleg@redhat.com, tglx@linutronix.de, Jens Axboe Subject: [PATCH 3/5] kernel: add support for TIF_NOTIFY_SIGNAL Date: Thu, 15 Oct 2020 07:16:59 -0600 Message-Id: <20201015131701.511523-4-axboe@kernel.dk> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201015131701.511523-1-axboe@kernel.dk> References: <20201015131701.511523-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org This adds TIF_NOTIFY_SIGNAL handling in the generic code, which if set, will return true if signal_pending() is used in a wait loop. That causes an exit of the loop so that notify_signal tracehooks can be run. If the wait loop is currently inside a system call, the system call is restarted once task_work has been processed. Signed-off-by: Jens Axboe --- arch/x86/kernel/signal.c | 2 +- include/linux/entry-common.h | 9 +++++++-- include/linux/entry-kvm.h | 4 ++-- include/linux/sched/signal.h | 11 ++++++++++- include/linux/tracehook.h | 27 +++++++++++++++++++++++++++ kernel/entry/common.c | 6 +++--- kernel/entry/kvm.c | 3 +++ 7 files changed, 53 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index be0d7d4152ec..d18304e84c09 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -804,7 +804,7 @@ static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) * want to handle. Thus you cannot kill init even with a SIGKILL even by * mistake. */ -void arch_do_signal(struct pt_regs *regs) +void arch_do_signal(struct pt_regs *regs, unsigned long ti_work) { struct ksignal ksig; diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 159c7476b11b..42e899b3b4a1 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -37,6 +37,10 @@ # define _TIF_UPROBE (0) #endif +#ifndef _TIF_NOTIFY_SIGNAL +# define _TIF_NOTIFY_SIGNAL (0) +#endif + /* * TIF flags handled in syscall_enter_from_usermode() */ @@ -69,7 +73,7 @@ #define EXIT_TO_USER_MODE_WORK \ (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ - _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | \ + _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \ ARCH_EXIT_TO_USER_MODE_WORK) /** @@ -261,10 +265,11 @@ static __always_inline void arch_exit_to_user_mode(void) { } /** * arch_do_signal - Architecture specific signal delivery function * @regs: Pointer to currents pt_regs + * @ti_work: task thread info work flags * * Invoked from exit_to_user_mode_loop(). */ -void arch_do_signal(struct pt_regs *regs); +void arch_do_signal(struct pt_regs *regs, unsigned long ti_work); /** * arch_syscall_exit_tracehook - Wrapper around tracehook_report_syscall_exit() diff --git a/include/linux/entry-kvm.h b/include/linux/entry-kvm.h index 0cef17afb41a..9b93f8584ff7 100644 --- a/include/linux/entry-kvm.h +++ b/include/linux/entry-kvm.h @@ -11,8 +11,8 @@ # define ARCH_XFER_TO_GUEST_MODE_WORK (0) #endif -#define XFER_TO_GUEST_MODE_WORK \ - (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ +#define XFER_TO_GUEST_MODE_WORK \ + (_TIF_NEED_RESCHED | _TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL | \ _TIF_NOTIFY_RESUME | ARCH_XFER_TO_GUEST_MODE_WORK) struct kvm_vcpu; diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 404145dc536e..b2ecc34284b0 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -360,6 +360,15 @@ static inline int task_sigpending(struct task_struct *p) static inline int signal_pending(struct task_struct *p) { +#if defined(CONFIG_GENERIC_ENTRY) && defined(TIF_NOTIFY_SIGNAL) + /* + * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same + * behavior in terms of ensuring that we break out of wait loops + * so that notify signal callbacks can be processed. + */ + if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL))) + return 1; +#endif return task_sigpending(p); } @@ -507,7 +516,7 @@ extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize); static inline void restore_saved_sigmask_unless(bool interrupted) { if (interrupted) - WARN_ON(!test_thread_flag(TIF_SIGPENDING)); + WARN_ON(!signal_pending(current)); else restore_saved_sigmask(); } diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index b480e1a07ed8..0a5bb866e7a6 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -198,4 +198,31 @@ static inline void tracehook_notify_resume(struct pt_regs *regs) blkcg_maybe_throttle_current(); } +/* + * called by exit_to_user_mode_loop() if ti_work & _TIF_NOTIFY_SIGNAL. This + * is currently used by TWA_SIGNAL based task_work, which requires breaking + * wait loops to ensure that task_work is noticed and run. + */ +static inline void tracehook_notify_signal(void) +{ +#if defined(CONFIG_GENERIC_ENTRY) && defined(TIF_NOTIFY_SIGNAL) + clear_thread_flag(TIF_NOTIFY_SIGNAL); + smp_mb__after_atomic(); + if (current->task_works) + task_work_run(); +#endif +} + +/* + * Called when we have work to process from exit_to_user_mode_loop() + */ +static inline void set_notify_signal(struct task_struct *task) +{ +#if defined(CONFIG_GENERIC_ENTRY) && defined(TIF_NOTIFY_SIGNAL) + if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) && + !wake_up_state(task, TASK_INTERRUPTIBLE)) + kick_process(task); +#endif +} + #endif /* */ diff --git a/kernel/entry/common.c b/kernel/entry/common.c index d20ab4ac7183..bd3cf6279e94 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -135,7 +135,7 @@ static __always_inline void exit_to_user_mode(void) } /* Workaround to allow gradual conversion of architecture code */ -void __weak arch_do_signal(struct pt_regs *regs) { } +void __weak arch_do_signal(struct pt_regs *regs, unsigned long ti_work) { } static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, unsigned long ti_work) @@ -157,8 +157,8 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, if (ti_work & _TIF_PATCH_PENDING) klp_update_patch_state(current); - if (ti_work & _TIF_SIGPENDING) - arch_do_signal(regs); + if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) + arch_do_signal(regs, ti_work); if (ti_work & _TIF_NOTIFY_RESUME) { tracehook_notify_resume(regs); diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c index b6678a5e3cf6..49972ee99aff 100644 --- a/kernel/entry/kvm.c +++ b/kernel/entry/kvm.c @@ -8,6 +8,9 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work) do { int ret; + if (ti_work & _TIF_NOTIFY_SIGNAL) + tracehook_notify_signal(); + if (ti_work & _TIF_SIGPENDING) { kvm_handle_signal_exit(vcpu); return -EINTR; -- 2.28.0