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 C584FC433E6 for ; Sat, 29 Aug 2020 13:08:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A11142076D for ; Sat, 29 Aug 2020 13:08:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598706491; bh=c6aHLTXA8+bAd28taNJRYdsVPrpGYfT7NmXPwefOwaM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=j2E893Qaiuld9nzeCYS4nr8t1aQ+s2B4o3eHPdemvT6uhI9f8LNc4JJs3gCfK1wKy mZFjD+0QjoQUihNNsYRVb95tuSdPzJvGUdDTZv6+gNtjbhacaI9XNz/6NlNpm960XN SbmqCiHSHc/8CnjFVkR4lwXISWFCav0WtmAFaPGM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728087AbgH2NHd (ORCPT ); Sat, 29 Aug 2020 09:07:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:54134 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728202AbgH2NC5 (ORCPT ); Sat, 29 Aug 2020 09:02:57 -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 1568A207BB; Sat, 29 Aug 2020 13:02:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598706177; bh=c6aHLTXA8+bAd28taNJRYdsVPrpGYfT7NmXPwefOwaM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KgE/K2IvGetKfhiPHtBF5TEJ5O1PhpzIPFaNqbEUnylRIrcZ4Ph0T+Am5Mb1Gtq/4 TN6Sr+iuAwh4IQI9Y8KcF52S4PLYt8in1VWh3KJG4M0csoyimH6sK6F/GfVpncoSlH k9wozdni+m/lR48n+Bb3oIpEzU6FMLXw9D0oN9Bk= From: Masami Hiramatsu To: linux-kernel@vger.kernel.org, Peter Zijlstra Cc: Eddy_Wu@trendmicro.com, x86@kernel.org, davem@davemloft.net, rostedt@goodmis.org, naveen.n.rao@linux.ibm.com, anil.s.keshavamurthy@intel.com, linux-arch@vger.kernel.org, cameron@moodycamel.com, oleg@redhat.com, will@kernel.org, paulmck@kernel.org, mhiramat@kernel.org Subject: [PATCH v5 15/21] kprobes: Free kretprobe_instance with rcu callback Date: Sat, 29 Aug 2020 22:02:47 +0900 Message-Id: <159870616685.1229682.11978742048709542226.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <159870598914.1229682.15230803449082078353.stgit@devnote2> References: <159870598914.1229682.15230803449082078353.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 c6a913e608b7..663be8debf25 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 211138225fa5..0676868f1ac2 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, *last = NULL; - struct hlist_head *head, empty_rp; + struct hlist_head *head; struct hlist_node *tmp; unsigned long flags; kprobe_opcode_t *correct_ret_addr = NULL; bool skipped = false; - INIT_HLIST_HEAD(&empty_rp); kretprobe_hash_lock(current, &head, &flags); /* @@ -2011,7 +2003,7 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, __this_cpu_write(current_kprobe, prev); } - recycle_rp_inst(ri, &empty_rp); + recycle_rp_inst(ri); if (ri == last) break; @@ -2019,11 +2011,6 @@ 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 (unsigned long)correct_ret_addr; } NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)