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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 9A0CBC433FE for ; Tue, 14 Sep 2021 21:41:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7BD40610A6 for ; Tue, 14 Sep 2021 21:41:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234971AbhINVm7 (ORCPT ); Tue, 14 Sep 2021 17:42:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:45770 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232891AbhINVm7 (ORCPT ); Tue, 14 Sep 2021 17:42:59 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AD86F60F46; Tue, 14 Sep 2021 21:41:40 +0000 (UTC) Date: Tue, 14 Sep 2021 17:41:34 -0400 From: Steven Rostedt To: Jiri Olsa Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Subject: Re: [PATCH 7/8] ftrace: Add multi direct modify interface Message-ID: <20210914174134.1d8fd944@oasis.local.home> In-Reply-To: <20210831095017.412311-8-jolsa@kernel.org> References: <20210831095017.412311-1-jolsa@kernel.org> <20210831095017.412311-8-jolsa@kernel.org> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 31 Aug 2021 11:50:16 +0200 Jiri Olsa wrote: > Adding interface to modify registered direct function > for ftrace_ops. Adding following function: > > modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) > > The function changes the currently registered direct > function for all attached functions. > > Signed-off-by: Jiri Olsa > --- > include/linux/ftrace.h | 6 ++++++ > kernel/trace/ftrace.c | 43 ++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 49 insertions(+) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index e40b5201c16e..f3ba6366f7af 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -318,6 +318,8 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry, > unsigned long ftrace_find_rec_direct(unsigned long ip); > int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr); > int unregister_ftrace_direct_multi(struct ftrace_ops *ops); > +int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr); > + > #else > struct ftrace_ops; > # define ftrace_direct_func_count 0 > @@ -357,6 +359,10 @@ static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops) > { > return -ENODEV; > } > +static inline int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) > +{ > + return -ENODEV; > +} > #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ > > #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 7243769493c9..59940a6a907c 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -5518,6 +5518,49 @@ int unregister_ftrace_direct_multi(struct ftrace_ops *ops) > return err; > } > EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi); > + Needs kernel doc comments. > +int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) > +{ > + struct ftrace_hash *hash = ops->func_hash->filter_hash; > + struct ftrace_func_entry *entry, *iter; > + int i, size; > + int err; > + > + if (check_direct_multi(ops)) > + return -EINVAL; > + if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) > + return -EINVAL; > + > + mutex_lock(&direct_mutex); > + mutex_lock(&ftrace_lock); > + > + /* > + * Shutdown the ops, change 'direct' pointer for each > + * ops entry in direct_functions hash and startup the > + * ops back again. > + */ > + err = ftrace_shutdown(ops, 0); This needs to be commented that there's going to be a rather large time frame that there will be no callbacks happening while this update occurs. A better solution, that prevents having to do this, is to first change the function fentry's to call the ftrace list loop function, that calls the ftrace_ops list, and will call the direct call via the ops in the loop. Have the ops->func call the new direct function (all will be immediately affected). Update the entries, and then switch from the loop back to the direct caller. -- Steve > + if (err) > + goto out_unlock; > + > + size = 1 << hash->size_bits; > + for (i = 0; i < size; i++) { > + hlist_for_each_entry(iter, &hash->buckets[i], hlist) { > + entry = __ftrace_lookup_ip(direct_functions, iter->ip); > + if (!entry) > + continue; > + entry->direct = addr; > + } > + } > + > + err = ftrace_startup(ops, 0); > + > + out_unlock: > + mutex_unlock(&ftrace_lock); > + mutex_unlock(&direct_mutex); > + return err; > +} > +EXPORT_SYMBOL_GPL(modify_ftrace_direct_multi); > #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ > > /**