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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 117A0FC6197 for ; Fri, 8 Nov 2019 21:35:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E11BF2178F for ; Fri, 8 Nov 2019 21:34:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733145AbfKHVe6 (ORCPT ); Fri, 8 Nov 2019 16:34:58 -0500 Received: from mail.kernel.org ([198.145.29.99]:34946 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732960AbfKHVex (ORCPT ); Fri, 8 Nov 2019 16:34:53 -0500 Received: from gandalf.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 369B721882; Fri, 8 Nov 2019 21:34:52 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.92.2) (envelope-from ) id 1iTBu7-0007zz-5F; Fri, 08 Nov 2019 16:34:51 -0500 Message-Id: <20191108213451.044504936@goodmis.org> User-Agent: quilt/0.65 Date: Fri, 08 Nov 2019 16:28:44 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , X86 ML , Nadav Amit , Andy Lutomirski , Dave Hansen , Song Liu , Masami Hiramatsu , Peter Zijlstra , Daniel Bristot de Oliveira , Alexei Starovoitov , Josh Poimboeuf Subject: [PATCH 10/10] ftrace/x86: Add a counter to test function_graph with direct References: <20191108212834.594904349@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" As testing for direct calls from the function graph tracer adds a little overhead (which is a lot when tracing every function), add a counter that can be used to test if function_graph tracer needs to test for a direct caller or not. It would have been nicer if we could use a static branch, but the static branch logic fails when used within the function graph tracer trampoline. Signed-off-by: Steven Rostedt (VMware) --- arch/x86/kernel/ftrace.c | 8 +++++--- include/linux/ftrace.h | 2 ++ kernel/trace/ftrace.c | 4 ++++ 3 files changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index fef283f6341d..060a361d9d11 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -1049,9 +1049,11 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, * return address is actually off by one word, and we * need to adjust for that. */ - if (ftrace_find_direct_func(self_addr + MCOUNT_INSN_SIZE)) { - self_addr = *parent; - parent++; + if (ftrace_direct_func_count) { + if (ftrace_find_direct_func(self_addr + MCOUNT_INSN_SIZE)) { + self_addr = *parent; + parent++; + } } /* diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 2bc7bd6b8387..55647e185141 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -247,10 +247,12 @@ static inline void ftrace_free_mem(struct module *mod, void *start, void *end) { #endif /* CONFIG_FUNCTION_TRACER */ #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +extern int ftrace_direct_func_count; int register_ftrace_direct(unsigned long ip, unsigned long addr); int unregister_ftrace_direct(unsigned long ip, unsigned long addr); struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr); #else +# define ftrace_direct_func_count 0 static inline int register_ftrace_direct(unsigned long ip, unsigned long addr) { return -ENODEV; diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index f57ab704dc2d..0e18ec707a88 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2367,6 +2367,7 @@ ftrace_find_tramp_ops_new(struct dyn_ftrace *rec) /* Protected by rcu_tasks for reading, and direct_mutex for writing */ static struct ftrace_hash *direct_functions = EMPTY_HASH; static DEFINE_MUTEX(direct_mutex); +int ftrace_direct_func_count; /* * Search the direct_functions hash to see if the given instruction pointer @@ -5059,6 +5060,7 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr) direct->addr = addr; direct->count = 0; list_add_rcu(&direct->next, &ftrace_direct_funcs); + ftrace_direct_func_count++; } entry->ip = ip; @@ -5084,6 +5086,7 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr) if (free_hash) free_ftrace_hash(free_hash); free_hash = NULL; + ftrace_direct_func_count--; } } else { if (!direct->count) @@ -5144,6 +5147,7 @@ int unregister_ftrace_direct(unsigned long ip, unsigned long addr) list_del_rcu(&direct->next); synchronize_rcu_tasks(); kfree(direct); + ftrace_direct_func_count--; } } out_unlock: -- 2.23.0