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 DA213C433E2 for ; Fri, 28 Aug 2020 12:32:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ACCCE2078A for ; Fri, 28 Aug 2020 12:32:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598617926; bh=acFyl9JrDMCmoEbbJea4CsEvyDU1jq2VHmQ0xKYxWfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CHrhJL3Q+QcFtWG6LuFrRLdroq3+b2HqqJcuvpGhZAVeM344XvwbNl4RrS7mBLjsX Sp7SDWcU2Q8WfeBF/32pSop+4zUBpwLJ2ko/7YzOLWsQtkS5NvCI2t8GdPSZi2h9xC EwQM1MJAfAzofaXW0+hJrRGVNZR24qyVbXKAygc0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729199AbgH1McB (ORCPT ); Fri, 28 Aug 2020 08:32:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:40692 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729402AbgH1M32 (ORCPT ); Fri, 28 Aug 2020 08:29:28 -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 C673820872; Fri, 28 Aug 2020 12:29:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598617767; bh=acFyl9JrDMCmoEbbJea4CsEvyDU1jq2VHmQ0xKYxWfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Xtc3eOzlOZs+CHz2uQcpWu/uMo8dc4HGcuHccA6/4rd1wRvkDkrEYilIvOVoJpmph 0ak3njtJuhfNnIr78n4sx0YngP1zqsXDvTFXnOucoO9o0QICHPk52W3EkKADsSqOLn qLPWxLDHQnqKk++AXIiCZls8cV+jlm0WUElg/rTI= 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 v4 15/23] kprobes: Free kretprobe_instance with rcu callback Date: Fri, 28 Aug 2020 21:29:22 +0900 Message-Id: <159861776262.992023.16481397943804064199.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <159861759775.992023.12553306821235086809.stgit@devnote2> References: <159861759775.992023.12553306821235086809.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 c8de76d230e3..807d4429e8a2 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); /* @@ -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 (ri == last) break; @@ -2017,11 +2009,6 @@ 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)