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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 19149C388F7 for ; Tue, 10 Nov 2020 04:01:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF3252063A for ; Tue, 10 Nov 2020 04:01:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="PDiOn1pX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732649AbgKJEBi (ORCPT ); Mon, 9 Nov 2020 23:01:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:56898 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733066AbgKJDzb (ORCPT ); Mon, 9 Nov 2020 22:55:31 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4263221D91; Tue, 10 Nov 2020 03:55:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604980531; bh=ccViNF9rlUQkeH+89rx7H+w/4vI3jc3FmSmcT5V74EM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PDiOn1pXpCAs1zKd4BuHC0jYzwj6SgAMvRI7KRLQUASn41hqKhpyKmkhsrkz2YJQz 5WuzJbIwgssiYVkjWWukSFb08XprPN154voYToLriMA+Sx3JOW2nF1wdDTWdqfhKsP az6jwWVHfJy1VnhXFhz6d4ja/M187FDu0Wfnk5Bo= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Steven Rostedt (VMware)" , Peter Zijlstra , Masami Hiramatsu , Sasha Levin Subject: [PATCH AUTOSEL 5.4 36/42] kprobes: Tell lockdep about kprobe nesting Date: Mon, 9 Nov 2020 22:54:34 -0500 Message-Id: <20201110035440.424258-36-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201110035440.424258-1-sashal@kernel.org> References: <20201110035440.424258-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" [ Upstream commit 645f224e7ba2f4200bf163153d384ceb0de5462e ] Since the kprobe handlers have protection that prohibits other handlers from executing in other contexts (like if an NMI comes in while processing a kprobe, and executes the same kprobe, it will get fail with a "busy" return). Lockdep is unaware of this protection. Use lockdep's nesting api to differentiate between locks taken in INT3 context and other context to suppress the false warnings. Link: https://lore.kernel.org/r/20201102160234.fa0ae70915ad9e2b21c08b85@kernel.org Cc: Peter Zijlstra Acked-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/kprobes.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 283c8b01ce789..2a38e3553c80b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1215,7 +1215,13 @@ __acquires(hlist_lock) *head = &kretprobe_inst_table[hash]; hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_lock_irqsave(hlist_lock, *flags); + /* + * Nested is a workaround that will soon not be needed. + * There's other protections that make sure the same lock + * is not taken on the same CPU that lockdep is unaware of. + * Differentiate when it is taken in NMI context. + */ + raw_spin_lock_irqsave_nested(hlist_lock, *flags, !!in_nmi()); } NOKPROBE_SYMBOL(kretprobe_hash_lock); @@ -1224,7 +1230,13 @@ static void kretprobe_table_lock(unsigned long hash, __acquires(hlist_lock) { raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_lock_irqsave(hlist_lock, *flags); + /* + * Nested is a workaround that will soon not be needed. + * There's other protections that make sure the same lock + * is not taken on the same CPU that lockdep is unaware of. + * Differentiate when it is taken in NMI context. + */ + raw_spin_lock_irqsave_nested(hlist_lock, *flags, !!in_nmi()); } NOKPROBE_SYMBOL(kretprobe_table_lock); @@ -1911,7 +1923,12 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) /* TODO: consider to only swap the RA after the last pre_handler fired */ hash = hash_ptr(current, KPROBE_HASH_BITS); - raw_spin_lock_irqsave(&rp->lock, flags); + /* + * Nested is a workaround that will soon not be needed. + * There's other protections that make sure the same lock + * is not taken on the same CPU that lockdep is unaware of. + */ + raw_spin_lock_irqsave_nested(&rp->lock, flags, 1); if (!hlist_empty(&rp->free_instances)) { ri = hlist_entry(rp->free_instances.first, struct kretprobe_instance, hlist); @@ -1922,7 +1939,7 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) ri->task = current; if (rp->entry_handler && rp->entry_handler(ri, regs)) { - raw_spin_lock_irqsave(&rp->lock, flags); + raw_spin_lock_irqsave_nested(&rp->lock, flags, 1); hlist_add_head(&ri->hlist, &rp->free_instances); raw_spin_unlock_irqrestore(&rp->lock, flags); return 0; -- 2.27.0