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=-14.1 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,USER_AGENT_GIT autolearn=unavailable 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 00544C433DF for ; Thu, 27 Aug 2020 16:40:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF89522BEA for ; Thu, 27 Aug 2020 16:40:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598546455; bh=99qlixoES1XGgdUzUQy3aMnH6fHb80jko6dmcJ0RG6Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NOcljxK7qG63/mS+/bKpI1kASh78rDuJIs1wj/AGpESNPrb0iYFBVEhKoIpVQBdZe G0lFWA4sKIHRL3a5TCK3eUk6Wx9vOeJkzbsMbGLddgAIruHJ+awZAZEhob6C2eNeuo hHbK/LOB9K6cDMEY1wr/R0hyZSnsp30XFHRIsqQI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728155AbgH0Qkx (ORCPT ); Thu, 27 Aug 2020 12:40:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:48080 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728141AbgH0Qku (ORCPT ); Thu, 27 Aug 2020 12:40:50 -0400 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 33CAA2177B; Thu, 27 Aug 2020 16:40:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598546449; bh=99qlixoES1XGgdUzUQy3aMnH6fHb80jko6dmcJ0RG6Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h4720MpCI+wDtv2Tq0YmEcQtKV2f2tCV1nU7+ITLPRxaOHm3/PdsklTcNC7Gw3rzt Te4FWzhPSYNWT3gw1OS5p7OjPi0i2zF1SET/xAmG2YR5PfPAT7Tl/DpcC7opaAMavL +H7wEOxPylob5iYZQt1vePcKlS3PZpGTbaOJqR3g= From: Masami Hiramatsu To: linux-kernel@vger.kernel.org, Peter Zijlstra Cc: Eddy Wu , x86@kernel.org, "David S . Miller" , Steven Rostedt , Ingo Molnar , "Naveen N . Rao" , Anil S Keshavamurthy , linux-arch@vger.kernel.org, guoren@kernel.org Subject: [PATCH v3 15/16] kprobes: Free kretprobe_instance with rcu callback Date: Fri, 28 Aug 2020 01:40:46 +0900 Message-Id: <159854644641.736475.2495205002588583050.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <159854631442.736475.5062989489155389472.stgit@devnote2> References: <159854631442.736475.5062989489155389472.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Free kretprobe_instance with rcu callback instead of directly freeing the object in the kretprobe handler context. This will make kretprobe run safer in NMI context. Signed-off-by: Masami Hiramatsu --- Changes in v3: - Stick the rcu_head with hlist_node in kretprobe_instance - Make recycle_rp_inst() static --- include/linux/kprobes.h | 6 ++++-- kernel/kprobes.c | 25 ++++++------------------- 2 files changed, 10 insertions(+), 21 deletions(-) diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 46a7afcf5ec0..b4388abedecf 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -156,7 +156,10 @@ struct kretprobe { }; struct kretprobe_instance { - struct hlist_node hlist; + union { + struct hlist_node hlist; + struct rcu_head rcu; + }; struct kretprobe *rp; kprobe_opcode_t *ret_addr; struct task_struct *task; @@ -395,7 +398,6 @@ int register_kretprobes(struct kretprobe **rps, int num); void unregister_kretprobes(struct kretprobe **rps, int num); void kprobe_flush_task(struct task_struct *tk); -void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head); int disable_kprobe(struct kprobe *kp); int enable_kprobe(struct kprobe *kp); diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 311033e4b8e4..ce788574883b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1223,8 +1223,7 @@ void kprobes_inc_nmissed_count(struct kprobe *p) } NOKPROBE_SYMBOL(kprobes_inc_nmissed_count); -void recycle_rp_inst(struct kretprobe_instance *ri, - struct hlist_head *head) +static void recycle_rp_inst(struct kretprobe_instance *ri) { struct kretprobe *rp = ri->rp; @@ -1236,8 +1235,7 @@ void recycle_rp_inst(struct kretprobe_instance *ri, hlist_add_head(&ri->hlist, &rp->free_instances); raw_spin_unlock(&rp->lock); } else - /* Unregistering */ - hlist_add_head(&ri->hlist, head); + kfree_rcu(ri, rcu); } NOKPROBE_SYMBOL(recycle_rp_inst); @@ -1313,7 +1311,7 @@ void kprobe_busy_end(void) void kprobe_flush_task(struct task_struct *tk) { struct kretprobe_instance *ri; - struct hlist_head *head, empty_rp; + struct hlist_head *head; struct hlist_node *tmp; unsigned long hash, flags = 0; @@ -1323,19 +1321,14 @@ void kprobe_flush_task(struct task_struct *tk) kprobe_busy_begin(); - INIT_HLIST_HEAD(&empty_rp); hash = hash_ptr(tk, KPROBE_HASH_BITS); head = &kretprobe_inst_table[hash]; kretprobe_table_lock(hash, &flags); hlist_for_each_entry_safe(ri, tmp, head, hlist) { if (ri->task == tk) - recycle_rp_inst(ri, &empty_rp); + recycle_rp_inst(ri); } kretprobe_table_unlock(hash, &flags); - hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { - hlist_del(&ri->hlist); - kfree(ri); - } kprobe_busy_end(); } @@ -1936,13 +1929,12 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, void *frame_pointer) { struct kretprobe_instance *ri = NULL; - struct hlist_head *head, empty_rp; + struct hlist_head *head; struct hlist_node *tmp; unsigned long flags, orig_ret_address = 0; kprobe_opcode_t *correct_ret_addr = NULL; bool skipped = false; - INIT_HLIST_HEAD(&empty_rp); kretprobe_hash_lock(current, &head, &flags); /* @@ -2009,7 +2001,7 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, __this_cpu_write(current_kprobe, &kprobe_busy); } - recycle_rp_inst(ri, &empty_rp); + recycle_rp_inst(ri); if (orig_ret_address != trampoline_address) /* @@ -2022,11 +2014,6 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, kretprobe_hash_unlock(current, &flags); - hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { - hlist_del(&ri->hlist); - kfree(ri); - } - return orig_ret_address; } NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)