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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9C47C38A2D for ; Wed, 26 Oct 2022 15:42:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233722AbiJZPmj (ORCPT ); Wed, 26 Oct 2022 11:42:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232842AbiJZPmj (ORCPT ); Wed, 26 Oct 2022 11:42:39 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5197DD88F; Wed, 26 Oct 2022 08:42:38 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5BA8761FAD; Wed, 26 Oct 2022 15:42:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB704C433C1; Wed, 26 Oct 2022 15:42:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666798957; bh=JVjHGhtOduan1YHejgdu5cvny0hpSJ1Ttt+TrgSzmx0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=QnBjOq5qqhBq2AHOTu1JO4o1st3C5s+ONPm4KBesyA4YS4EpKKrw9OXBaTaiWYXRb cvsIo9twFbcblerwE5wRD6EZ0N/JpwoAdQb3l5jRjNwkJaaj+74USs51AJ10k/M93S iOrXCrgmPtrvSoP93uqt1+syHxrUM1pZPIXXG8wUvEC9plnpeWoxkbXsmd2ZFOZ2h7 h9O6yG47mgiTVir4fRqgw37JB1FHgPki1AZ80bZ1/1ZNEpiCOe5VqfR+Rl3a9hNfHO 4yTDY5WWDdA4i+cHR0wrZPnMAudpeByOGGq3tY3wfKHt2gjRyWVuTzNcAHBDCxkQiM SXxr7QKAMk/cQ== Date: Thu, 27 Oct 2022 00:42:34 +0900 From: Masami Hiramatsu (Google) To: "Masami Hiramatsu (Google)" Cc: LKML , Steven Rostedt , Linux Trace Kernel , Primiano Tucci Subject: Re: [PATCH 1/2] tracing/probes: Add symstr type for dynamic events Message-Id: <20221027004234.6f3097f4bf4a18dfddf9ae56@kernel.org> In-Reply-To: <166642073074.718058.9841757174640040227.stgit@mhiramat.roam.corp.google.com> References: <166642072204.718058.1479401089273534841.stgit@mhiramat.roam.corp.google.com> <166642073074.718058.9841757174640040227.stgit@mhiramat.roam.corp.google.com> X-Mailer: Sylpheed 3.8.0beta1 (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-trace-kernel@vger.kernel.org On Sat, 22 Oct 2022 15:38:50 +0900 "Masami Hiramatsu (Google)" wrote: > From: Masami Hiramatsu (Google) > > Add 'symstr' type for storing the kernel symbol as a string data > instead of the symbol address. This allows us to filter the > events by wildcard symbol name. > > e.g. > # echo 'e:wqfunc workqueue.workqueue_execute_start symname=$function:symstr' >> dynamic_events > # cat events/eprobes/wqfunc/format > name: wqfunc > ID: 2110 > format: > field:unsigned short common_type; offset:0; size:2; signed:0; > field:unsigned char common_flags; offset:2; size:1; signed:0; > field:unsigned char common_preempt_count; offset:3; size:1; signed:0; > field:int common_pid; offset:4; size:4; signed:1; > > field:__data_loc char[] symname; offset:8; size:4; signed:1; > > print fmt: " symname=\"%s\"", __get_str(symname) > > Note that there is already 'symbol' type which just change the > print format (so it still stores the symbol address in the tracing > ring buffer.) On the other hand, 'symstr' type stores the actual > "symbol+offset/size" data as a string. > > Signed-off-by: Masami Hiramatsu (Google) > --- [...] > diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h > index b3bdb8ddb862..d57a3143929a 100644 > --- a/kernel/trace/trace_probe_tmpl.h > +++ b/kernel/trace/trace_probe_tmpl.h > @@ -67,6 +67,37 @@ probe_mem_read(void *dest, void *src, size_t size); > static nokprobe_inline int > probe_mem_read_user(void *dest, void *src, size_t size); > > +static nokprobe_inline int > +fetch_store_symstrlen(unsigned long addr) > +{ > + char namebuf[KSYM_SYMBOL_LEN]; > + int ret; > + > + ret = sprint_symbol(namebuf, addr); > + if (ret < 0) > + return 0; > + > + return strlen(namebuf) + 1; Ah, sprint_symbol() returns the length. This strlen() is redundant. Let me update the patch. Thank you, -- Masami Hiramatsu (Google)