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 64A6B1D0E18; Wed, 2 Oct 2024 14:31:13 +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=1727879473; cv=none; b=iXAm0aIrv3Bp1YTWC5MIzXLyFQwRyHVaXFgqvgDtG0yI17fMtsdet+WRFqpKtetcggo45xjV/Ec4GZ8PBUfWr9gXDxy9MUlbNIlO0nuzCJ4+2z7UcNCkwdj/xV4YGXSTyKQHt7uYtqckyNogzZ4+ylcxnfntnEaQF4mKWZvjuxg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727879473; c=relaxed/simple; bh=7QrNOvyhNom77KQGrs/t7eMr6qYJYQNHCPzn2XeEmZk=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=kCxRUoQiV1zqztNS9IBZcGjVGJnmlJmIiXTeH+yS13szFwDqQzYGZUi95eIzLKKUgM+43jzpBvJPjFHwdsdHWyzO8+4yO7iWZNBFs4LgPLGobtzD2cRZLV+AU9XcND2Slsgaf9wcDEtMo2WcDlLgwHAC8Tu9L/wx2YDS6I/kWXM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eJKQKjtw; 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="eJKQKjtw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67049C4CEC5; Wed, 2 Oct 2024 14:31:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727879473; bh=7QrNOvyhNom77KQGrs/t7eMr6qYJYQNHCPzn2XeEmZk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=eJKQKjtwuljUQETX3A01ZIMibs/ViHavZ74RNwceIvmWzOaQ5RnRGKG22YgnKlBut vfkpP2b4ZfHgZDr9i84lgp1trq+pD9VcWU9K8c9xat9EGT1pKlx2JHYN17t/UOiYOw iRM2aHuwdZ0ejp+4auqwjM2QJIEtyUxSybw/9523lYeYAACGiy5beFokFcCYXBAw3O sgbQ2QwIuR+W1/VO3diF34mCXir9CSb8JA5gNBZZmczNq3dYMPXic59LnyC7N/oyof 6Xx0Y5o1XX92jex1p1VnXPdcPsj7nYOGV6SU28hWvfk/it08ZluzzWtO6p1R7382I8 jSFURQZ7W0GNQ== Date: Wed, 2 Oct 2024 23:31:08 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Will Deacon , Catalin Marinas , linux-arm-kernel@lists.infradead.org, Florent Revest , linux-trace-kernel@vger.kernel.org, LKML , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Mark Rutland Subject: Re: [PATCH v14 04/19] function_graph: Replace fgraph_ret_regs with ftrace_regs Message-Id: <20241002233108.9e4c2aaa09b8532870016dc0@kernel.org> In-Reply-To: <20241001193234.2acb6147@gandalf.local.home> References: <172615368656.133222.2336770908714920670.stgit@devnote2> <172615373091.133222.1812791604518973124.stgit@devnote2> <20240915051144.445681c2@rorschach.local.home> <20240917095538.GA27384@willie-the-truck> <20240930145548.08c8f666@gandalf.local.home> <20241002081037.e9b825f7456ce4815eccad1b@kernel.org> <20241001193234.2acb6147@gandalf.local.home> 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 Tue, 1 Oct 2024 19:32:34 -0400 Steven Rostedt wrote: > On Wed, 2 Oct 2024 08:10:37 +0900 > Masami Hiramatsu (Google) wrote: > > > > > > I may add some compiler hacks to enforce this. Something like: > > > > > > struct ftrace_regs { > > > void *nothing_to_see_here; > > > }; > > > > Yeah, OK. But sizeof(fregs) may be changed. (Shouldn't we do too?) > > Honestly, I don't think anything should be doing a sizeof(struct ftrace_regs) > > Heck, perhaps we should make it totally zero! > > struct ftrace_regs { > long nothing_here[]; > }; > > If someone needs to allocate, then we could provide a: > > ftrace_regs_size() > > helper function. Ah, Indeed. > > > > > > > > > And then change the arch code to be something like: > > > > > > // in arch/arm64/include/asm/ftrace.h: > > > > > > struct arch_ftrace_regs { > > > /* x0 - x8 */ > > > unsigned long regs[9]; > > > > > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS > > > unsigned long direct_tramp; > > > #else > > > unsigned long __unused; > > > #endif > > > > > > unsigned long fp; > > > unsigned long lr; > > > > > > unsigned long sp; > > > unsigned long pc; > > > }; > > > > And if it is pt_regs compatible, > > > > #define arch_ftrace_regs pt_regs > > > > ? > > > > Only if it is fully pt_regs compatible. Yeah, OK, this is good idea. Thank you, > > -- Steve -- Masami Hiramatsu (Google)