From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F375C7FBD3 for ; Wed, 13 Dec 2023 23:02:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="K/JIejC/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3535C433C7; Wed, 13 Dec 2023 23:02:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702508534; bh=ck0Wks3vinKRdAVQfZzby7MfciSNYq3TfXc0lwo7c7A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=K/JIejC/pPEqia4F7UFTTZiVgdmB/Q0wjqZ3W3Smm4+CbfCCwQ2bsJS9PoPiygCXx lRG4cOzO4386tW05bwNOlI+nIt2nBf8z7LpLDqoSRq2FMaVKqLy3Od2uGmwvharY44 h6zJsJRBPjWsBuVdQDN6MPlB5ibtLO4moElRt+VnKl3VhdRKBX0Hm2ua+MNXgd19kD 3JfUrVyqDCBUiwH0XFeR2pKzRmY5WtlgOe22AURlyuLdv+vGiySD6fBAUMRbgk/oDR g9kNXDcFcnA96XE+M5Zx9usubzLFYY2QRbsxRcDgCl1jgzf/RKsGY4P5mPGbNdBdue QXK9GjskOT3qA== Date: Thu, 14 Dec 2023 08:02:10 +0900 From: Masami Hiramatsu (Google) To: Naveen N Rao Cc: , , Steven Rostedt , Masami Hiramatsu , Srikar Dronamraju Subject: Re: [PATCH v3] trace/kprobe: Display the actual notrace function when rejecting a probe Message-Id: <20231214080210.99ff94d956307b036208520d@kernel.org> In-Reply-To: <20231213143914.1591175-1-naveen@kernel.org> References: <20231213143914.1591175-1-naveen@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 13 Dec 2023 20:09:14 +0530 Naveen N Rao wrote: > Trying to probe update_sd_lb_stats() using perf results in the below > message in the kernel log: > trace_kprobe: Could not probe notrace function _text > > This is because 'perf probe' specifies the kprobe location as an offset > from '_text': > $ sudo perf probe -D update_sd_lb_stats > p:probe/update_sd_lb_stats _text+1830728 > > However, the error message is misleading and doesn't help convey the > actual notrace function that is being probed. Fix this by looking up the > actual function name that is being probed. With this fix, we now get the > below message in the kernel log: > trace_kprobe: Could not probe notrace function update_sd_lb_stats.constprop.0 > > Signed-off-by: Naveen N Rao > --- > v3: Remove tk parameter from within_notrace_func() as suggested by > Masami > > kernel/trace/trace_kprobe.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 3d7a180a8427..dc36c6ed6131 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -449,9 +449,8 @@ static bool __within_notrace_func(unsigned long addr) > return !ftrace_location_range(addr, addr + size - 1); > } > > -static bool within_notrace_func(struct trace_kprobe *tk) > +static bool within_notrace_func(unsigned long addr) > { > - unsigned long addr = trace_kprobe_address(tk); > char symname[KSYM_NAME_LEN], *p; > > if (!__within_notrace_func(addr)) > @@ -471,12 +470,14 @@ static bool within_notrace_func(struct trace_kprobe *tk) > return true; > } > #else > -#define within_notrace_func(tk) (false) > +#define within_notrace_func(addr) (false) > #endif > > /* Internal register function - just handle k*probes and flags */ > static int __register_trace_kprobe(struct trace_kprobe *tk) > { > + unsigned long addr = trace_kprobe_address(tk); > + char symname[KSYM_NAME_LEN]; > int i, ret; > > ret = security_locked_down(LOCKDOWN_KPROBES); > @@ -486,9 +487,9 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) > if (trace_kprobe_is_registered(tk)) > return -EINVAL; > > - if (within_notrace_func(tk)) { > + if (within_notrace_func(addr)) { > pr_warn("Could not probe notrace function %s\n", > - trace_kprobe_symbol(tk)); > + lookup_symbol_name(addr, symname) ? trace_kprobe_symbol(tk) : symname); Can we just use %ps and (void *)trace_kprobe_address(tk) here? That will be simpler. Thank you, > return -EINVAL; > } > > > base-commit: 4758560fa268cecfa1144f015aa9f2525d164b7e > -- > 2.43.0 > -- Masami Hiramatsu (Google)