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 2CF04C4332F for ; Sun, 18 Dec 2022 01:39:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230019AbiLRBjQ (ORCPT ); Sat, 17 Dec 2022 20:39:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229480AbiLRBjO (ORCPT ); Sat, 17 Dec 2022 20:39:14 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF3B5E028 for ; Sat, 17 Dec 2022 17:39:12 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 823ABB80939 for ; Sun, 18 Dec 2022 01:39:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A6A7C433EF; Sun, 18 Dec 2022 01:39:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671327550; bh=vdPLodPjptqDtKrS8yKtZZdfufplFpLS9GpzIhaHVY0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kAgnnvwd0uDcZbYhpyT+e1C84in7/u77RbxpTGLADa3vOxA+AKtbZNsa1KRhBxKMW 2AQkSJb4K8TnJtKxkXl6xvMWR58YdiIq2O/Uvunssm8pTe6nV4llzfBhiscW7gQQpp phck4l5h42UggKKYvAq9F44NDMFYBLp/f9rkvJp9xk6BvdXS6nZp4/ZbCpyXqcv3m5 8oAg7jzcCZQd1+hXZ/wRVAvH7LSXfv5iQdB35aVsOQqHkqOMYcp/6DGXJsHpudYZ8K oTZ44hLXpTyiTPT6IhgvbTm4j/PnIBZuv2SYgJi7Lsd2M3fvxh7EyqJCsi1d3Cj9iU /Qhj8vEHNLghQ== Date: Sun, 18 Dec 2022 10:39:07 +0900 From: Masami Hiramatsu (Google) To: Donglin Peng Cc: rostedt@goodmis.org, mhiramat@kernel.org, xiehuan09@gmail.com, linux-kernel@vger.kernel.org, kernel test robot Subject: Re: [PATCH v4] tracing/probe: add a char type to show the character value of traced arguments Message-Id: <20221218103907.61bdd5a2ef5c2d175f585931@kernel.org> In-Reply-To: <20221215091346.33710-1-dolinux.peng@gmail.com> References: <20221215091346.33710-1-dolinux.peng@gmail.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=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Donglin, Thanks for updating you patch. And can you also send a test code update (tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_type.tc)? Thank you, On Thu, 15 Dec 2022 01:13:46 -0800 Donglin Peng wrote: > There are scenes that we want to show the character value of traced > arguments other than a decimal or hexadecimal or string value for debug > convinience. Add a new type named 'char' to do it. > > For example: > > The to be traced function is 'void demo_func(char type, char *name);', we > can add a kprobe event as follows to show argument values as we want: > > echo 'p:myprobe demo_func $arg1:char +0($arg2):char[2]' > kprobe_events > > we will get the following trace log: > > ... 95.451350: myprobe: (demo_func+0x0/0x29) arg1=A arg2={b,p} > > Signed-off-by: Donglin Peng > Acked-by: Masami Hiramatsu (Google) > Reported-by: kernel test robot > --- > Changes in v4: >  - update the example in the commit log > > Changes in v3: >  - update readme_msg > > Changes in v2: >  - fix build warnings reported by kernel test robot >  - modify commit log > --- > Documentation/trace/kprobetrace.rst | 3 ++- > kernel/trace/trace.c | 2 +- > kernel/trace/trace_probe.c | 2 ++ > kernel/trace/trace_probe.h | 1 + > 4 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst > index 4274cc6a2f94..007972a3c5c4 100644 > --- a/Documentation/trace/kprobetrace.rst > +++ b/Documentation/trace/kprobetrace.rst > @@ -58,7 +58,7 @@ Synopsis of kprobe_events > NAME=FETCHARG : Set NAME as the argument name of FETCHARG. > FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types > (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types > - (x8/x16/x32/x64), "string", "ustring" and bitfield > + (x8/x16/x32/x64), "char", "string", "ustring" and bitfield > are supported. > > (\*1) only for the probe on function entry (offs == 0). > @@ -80,6 +80,7 @@ E.g. 'x16[4]' means an array of x16 (2bytes hex) with 4 elements. > Note that the array can be applied to memory type fetchargs, you can not > apply it to registers/stack-entries etc. (for example, '$stack1:x8[8]' is > wrong, but '+8($stack):x8[8]' is OK.) > +Char type can be used to show the character value of traced arguments. > String type is a special type, which fetches a "null-terminated" string from > kernel space. This means it will fail and store NULL if the string container > has been paged out. "ustring" type is an alternative of string for user-space. > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 5cfc95a52bc3..a64e206f94e6 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -5615,7 +5615,7 @@ static const char readme_msg[] = > "\t $stack, $stack, $retval, $comm,\n" > #endif > "\t +|-[u](), \\imm-value, \\\"imm-string\"\n" > - "\t type: s8/16/32/64, u8/16/32/64, x8/16/32/64, string, symbol,\n" > + "\t type: s8/16/32/64, u8/16/32/64, x8/16/32/64, char, string, symbol,\n" > "\t b@/, ustring,\n" > "\t \\[\\]\n" > #ifdef CONFIG_HIST_TRIGGERS > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c > index 36dff277de46..a4abf7f6c295 100644 > --- a/kernel/trace/trace_probe.c > +++ b/kernel/trace/trace_probe.c > @@ -50,6 +50,7 @@ DEFINE_BASIC_PRINT_TYPE_FUNC(x8, u8, "0x%x") > DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x") > DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x") > DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx") > +DEFINE_BASIC_PRINT_TYPE_FUNC(char, u8, "%c") > > int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent) > { > @@ -93,6 +94,7 @@ static const struct fetch_type probe_fetch_types[] = { > ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0), > ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0), > ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0), > + ASSIGN_FETCH_TYPE_ALIAS(char, u8, u8, 0), > ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0), > > ASSIGN_FETCH_TYPE_END > diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h > index de38f1c03776..8c86aaa8b0c9 100644 > --- a/kernel/trace/trace_probe.h > +++ b/kernel/trace/trace_probe.h > @@ -164,6 +164,7 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(x16); > DECLARE_BASIC_PRINT_TYPE_FUNC(x32); > DECLARE_BASIC_PRINT_TYPE_FUNC(x64); > > +DECLARE_BASIC_PRINT_TYPE_FUNC(char); > DECLARE_BASIC_PRINT_TYPE_FUNC(string); > DECLARE_BASIC_PRINT_TYPE_FUNC(symbol); > > -- > 2.25.1 > -- Masami Hiramatsu (Google)