From patchwork Mon Dec 16 21:46:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13910627 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 CA2461B87E0; Mon, 16 Dec 2024 21:46:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734385561; cv=none; b=rXNZUfgXIgqXAAON/WQ62ikW35dz1063GgD/pwIRBOrnhZWonNaf6Ibngbjobq4ukexQ/CjFu1QinjYfvFpUXDdGSIeKSXHBN9efA35MonqTuj6vBJIw5NIukGFErDWRMLbAVQO+GCzFfBNLO4yKNGshu/7063yZtxchYuxMvP8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734385561; c=relaxed/simple; bh=nZYfZErGXFFaOfoXBYO5Ut9hZ2ETjfjWqO7Od6pEiWw=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=l5f2yy7fwUCTMa1etM/LzP7OG/z4dyfS1zkudjauOyZyChtdfEhn1M8WxV1SzN0yuQRxzbxExyn8A646oFv+ENf+j9rIwF9GMhwkhU0xyUzmitqaB7UBNEv2za1TdL8CDGnKx3FSIDk/4AM7epXpsaOx6a1St4rWCptsXgvWnRk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3BF36C4CED0; Mon, 16 Dec 2024 21:46:00 +0000 (UTC) Date: Mon, 16 Dec 2024 16:46:33 -0500 From: Steven Rostedt To: LKML , Linux Trace Kernel Cc: Masami Hiramatsu , Mathieu Desnoyers , Mark Rutland , Al Viro , Michal Simek , Jeff Xie Subject: [PATCH v1] ftrace: Do not find "true_parent" if HAVE_DYNAMIC_FTRACE_WITH_ARGS is not set Message-ID: <20241216164633.6df18e87@gandalf.local.home> X-Mailer: Claws Mail 3.20.0git84 (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 From: Steven Rostedt When function tracing and function graph tracing are both enabled (in different instances) the "parent" of some of the function tracing events is "return_to_handler" which is the trampoline used by function graph tracing. To fix this, ftrace_get_true_parent_ip() was introduced that returns the "true" parent ip instead of the trampoline. To do this, the ftrace_regs_get_stack_pointer() is used, which uses kernel_stack_pointer(). The problem is that microblaze does not implement kerenl_stack_pointer() so when function graph tracing is enabled, the build fails. But microblaze also does not enabled HAVE_DYNAMIC_FTRACE_WITH_ARGS. That option has to be enabled by the architecture to reliably get the values from the fregs parameter passed in. When that config is not set, the architecture can also pass in NULL, which is not tested for in that function and could cause the kernel to crash. Fixes: 60b1f578b578 ("ftrace: Get the true parent ip for function tracer") Reported-by: Al Viro Signed-off-by: Steven Rostedt (Google) --- Changes since v1: https://lore.kernel.org/20241211153634.69c75afa@batman.local.home - The issue with Microblaze was that it does not implement HAVE_DYNAMIC_FTRACE_WITH_ARGS and not that it didn't have kernel_stack_pointer() implemented. With the above config option implemented, function_get_true_parent_ip() will not work at all. kernel/trace/trace_functions.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c index 74c353164ca1..d358c9935164 100644 --- a/kernel/trace/trace_functions.c +++ b/kernel/trace/trace_functions.c @@ -176,7 +176,8 @@ static void function_trace_start(struct trace_array *tr) tracing_reset_online_cpus(&tr->array_buffer); } -#ifdef CONFIG_FUNCTION_GRAPH_TRACER +/* fregs are guaranteed not to be NULL if HAVE_DYNAMIC_FTRACE_WITH_ARGS is set */ +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) static __always_inline unsigned long function_get_true_parent_ip(unsigned long parent_ip, struct ftrace_regs *fregs) {