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 4059D1E4A4; Mon, 9 Dec 2024 06:36:56 +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=1733726217; cv=none; b=dhOUlLQa1YqwV+ou8BV2VwW5aFngta6PJuGl8bIDnmUYfcwIBb8/2tWoW/gjRFcpeyur7AK3vvYaG13NWaH1ebaEqLs5XZGlcVirTrnOfjiumumQIdbyS2gYREyWYKb8IaEi0mYQBgAkSkurJHPSW1Jh2DlzoISBERpgfhVl7ZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733726217; c=relaxed/simple; bh=SYyIX6eA60eKqyZW7rdqkdSCaHJa4XapYTOvdomFIfs=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=I+Bi7IgymWezmos3myyWF8nk+YbOO5qhXh6suDqilyuptMUOgXhpLg6QjsCy+MIOl0aWat+dQawjWfyC5SDAfOsDJndm9c+pzOBGe5954IY1Xjjjgyo8fRXZ8oVQTGRlJhC52tHbVz9RNjz0gT/ElIVTXbP1OOVgflsNqe3Zvik= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=brtgIYGR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="brtgIYGR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 197ABC4CED1; Mon, 9 Dec 2024 06:36:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733726216; bh=SYyIX6eA60eKqyZW7rdqkdSCaHJa4XapYTOvdomFIfs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=brtgIYGRJlhbiTK4WXsZwVjCivRBUknX+E7lOIhWPu4ITfqEDnuGiANKJ0stgvAgR e39J5KempFvX7NlCtDJ4BqFwUNQ/CYr0u9wvQmsHnYjMio6nKLVvJ+PU5ZSpCdX35E nLtmOfoBFZp3DtApZaJCpuddjyVusf9Xy88LSQ48IUTfWPSc/BzrO3V9Cqi77Jjq7T QMtpITcKE9+cwnKd6SI4Klipc07yyP1ooGJZ6LqaWMqMJrkgskU2Mnf6DzVU4hmHwh AEWr1cXLVUuPmceXqRJJV0AraCBGsRZpOeL34D+qxX7pfldH9Nzzp+cMhaAvod5KXm mJiFo+Q0WfujQ== Date: Mon, 9 Dec 2024 15:36:51 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Alexei Starovoitov , Florent Revest , linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Alexei Starovoitov , Jiri Olsa , Alan Maguire , Mark Rutland , linux-arch@vger.kernel.org Subject: Re: [PATCH v20 00/19] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Message-Id: <20241209153651.c622af218b5d4b2c2da76158@kernel.org> In-Reply-To: <20241207094710.21cdaceb@rorschach.local.home> References: <173344373580.50709.5332611753907139634.stgit@devnote2> <20241206172003.21af8b50ceed0b5e93a7771c@kernel.org> <20241207155136.dd69fbace1ae248c38b27d4b@kernel.org> <20241207094710.21cdaceb@rorschach.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-arch@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 Sat, 7 Dec 2024 09:47:10 -0500 Steven Rostedt wrote: > On Sat, 7 Dec 2024 15:51:36 +0900 > Masami Hiramatsu (Google) wrote: > > > This checks the handler is called with preempt off. > > > > On x86_64, the ftrace_graph_func calls function_graph_enter_regs() with > > ftrace_test_recursion_trylock() as below; > > > > void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, > > struct ftrace_ops *op, struct ftrace_regs *fregs) > > { > > struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs; > > unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs); > > unsigned long return_hooker = (unsigned long)&return_to_handler; > > unsigned long *parent = (unsigned long *)stack; > > int bit; > > > > if (unlikely(skip_ftrace_return())) > > return; > > > > bit = ftrace_test_recursion_trylock(ip, *parent); > > if (bit < 0) > > return; > > > > if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs)) > > *parent = return_hooker; > > > > ftrace_test_recursion_unlock(bit); > > } > > > > However, arm64 version does not; > > Hmm, I think we can move that recursion check out of the arch/x86 code > and into ftrace_graph_enter_regs(). OK, that's reasonable. Thanks, > > -- Steve -- Masami Hiramatsu (Google)