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 22051C4363A for ; Mon, 5 Oct 2020 15:05:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D03E420674 for ; Mon, 5 Oct 2020 15:05:03 +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="nAIDX9/B" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727090AbgJEPFC (ORCPT ); Mon, 5 Oct 2020 11:05:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727068AbgJEPEx (ORCPT ); Mon, 5 Oct 2020 11:04:53 -0400 Received: from mail-io1-xd41.google.com (mail-io1-xd41.google.com [IPv6:2607:f8b0:4864:20::d41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3E19C0613AD for ; Mon, 5 Oct 2020 08:04:51 -0700 (PDT) Received: by mail-io1-xd41.google.com with SMTP id u6so9461957iow.9 for ; Mon, 05 Oct 2020 08:04:51 -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=Ii95YAmxsR+HgUSEM40q9HyLP82YkIrTtWRY6tj6XKA=; b=nAIDX9/BdTq6VeJCKeMZcBw7nGz2yhGVdsicoPdXtbanu/guAngS7qgLAVBz6l6vkr sYmEwWx5JYOfO8GYgjyY0RcoYEXfAJpFcqd4mPPoy6710wWwD/xsFCgYJAYEeQH7gfM3 CL0v+6I8sofRV4d065ioHpXqrXWMk8BTey8hOVQ7dLFl8kbNjyyZPa02VbqQiEfzdfoq pvVi36rPFRhXLlmVKulsj6woHUhGg/RVVfXxRgBeSgQla6OMdFvCZ4c1gFtS61WLt+Lf KIu8GsDyzg5JhxSMfDhs8rPhcmVYH559zodEUXitSlMWqooyZpZJ9U8XMI5Mj8BrrQbo Zukg== 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=Ii95YAmxsR+HgUSEM40q9HyLP82YkIrTtWRY6tj6XKA=; b=k3l5cGpMwUqSXRCFRxL0Wh619cCBxatz5F4gKGlL9rUaskoIZZOdvVty0TIXhvzDeA mv+jVuGG7ZuZ9IzI+KGhn5QywYMQxFidV2rVJqwOoRyxHWoGmp9wt75RFfRGOSDaqX6F sMgV8iKkMVcMfJ9wZB0kkl3lhGasbwEgJtFWWRtOqVZrYDpbFEW7oNSdcjy600fU2T1e jNfb9h/ybY9M8JX+KgJGTkiMnkC6djW9Zzesw2c34CjWtulIe9wYVroPPLG8An2CoY9l l+XmkO+gUiFW0HGR/wO+hvUwLBWpKvZnl3vQtA4uJYbvRX9Pi9ZHUpM25pn/lQudi2En osHg== X-Gm-Message-State: AOAM533HeccONdrhr6Ljo+TPKvH678PXzjMsZ4UfglIHV6DeTK925l30 k8ciAG8nvlVek0qRMfpst5LHFpTs9A4BGQ== X-Google-Smtp-Source: ABdhPJy7/TJEUjF2NrxpmbDLU9aJ/Ak31e+0juJNyKzsYMCKQTUt5Vus6jdA0/UnyfWcwE7HiYIgqQ== X-Received: by 2002:a5d:96c1:: with SMTP id r1mr182313iol.147.1601910287866; Mon, 05 Oct 2020 08:04:47 -0700 (PDT) Received: from p1.localdomain ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id 15sm33140ilz.66.2020.10.05.08.04.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Oct 2020 08:04:47 -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 4/6] kernel: add support for TIF_NOTIFY_SIGNAL Date: Mon, 5 Oct 2020 09:04:36 -0600 Message-Id: <20201005150438.6628-5-axboe@kernel.dk> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201005150438.6628-1-axboe@kernel.dk> References: <20201005150438.6628-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 --- include/linux/entry-common.h | 6 +++++- include/linux/entry-kvm.h | 4 ++-- include/linux/sched/signal.h | 19 +++++++++++++++++-- include/linux/tracehook.h | 27 +++++++++++++++++++++++++++ kernel/entry/common.c | 5 ++++- kernel/entry/kvm.c | 3 +++ 6 files changed, 58 insertions(+), 6 deletions(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index ccfcc4769925..0929385b9d8d 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) /** 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 e6f34d8fbf4d..3117ff205a14 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) { +#ifdef 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); } @@ -506,10 +515,16 @@ extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize); static inline void restore_saved_sigmask_unless(bool interrupted) { - if (interrupted) + if (interrupted) { +#ifdef TIF_NOTIFY_SIGNAL + WARN_ON(!test_thread_flag(TIF_SIGPENDING) && + !test_thread_flag(TIF_NOTIFY_SIGNAL)); +#else WARN_ON(!test_thread_flag(TIF_SIGPENDING)); - else +#endif + } else { restore_saved_sigmask(); + } } static inline sigset_t *sigmask_to_save(void) diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index b480e1a07ed8..bec952f51439 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) +{ +#ifdef 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) +{ +#ifdef 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 0c0cc3cf3eba..6cf9f4fa0f6e 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -140,7 +140,7 @@ bool __weak arch_do_signal(struct pt_regs *regs) { return true; } static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, unsigned long ti_work) { - bool restart_sys = ti_work & _TIF_SIGPENDING; + bool restart_sys = ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL); /* * Before returning to user space ensure that all pending work @@ -159,6 +159,9 @@ 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_NOTIFY_SIGNAL) + tracehook_notify_signal(); + if ((ti_work & _TIF_SIGPENDING) && arch_do_signal(regs)) restart_sys = false; 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