From nobody Wed Dec 17 14:10:41 2025 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 06524C4167B for ; Mon, 27 Nov 2023 13:53:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233294AbjK0NxL (ORCPT ); Mon, 27 Nov 2023 08:53:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233286AbjK0NxH (ORCPT ); Mon, 27 Nov 2023 08:53:07 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF3A3D56 for ; Mon, 27 Nov 2023 05:53:12 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69C9DC433C7; Mon, 27 Nov 2023 13:53:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701093192; bh=HAB8fcsYhkztOqkqxJN8HQ+Use/Y/czjonQXwZoidcQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uIZrQVq+lXnVL0iTGzyTMigq0VYprpHHea7QEp0DUwqMa/mw57jtjUHOuti+awSJI Je9LXpbgbtOLePDnB/Qz/KxfFX0yg5V4HRpbz28in5M48FLLl9mdf1LW4JVfeXuIwS WN6aWPwufQbpYnFM+zX77ASxb2IhAm9VHFafxmf7FUTMeZPiQQETk7gTUmELI16Gfb 6mFoEcALesSrJHfNdtncl1RuVu8+Eto6THI5tIWy+ss28SCcMHqCy48yIg2PPoKYUR sNGBfgYDxoGWi3j9rPKiz88S5awEMyujyg4PCrRmq8UkIbad/nrr/ThSG+BXKYUMFG QE+Aeg8ZUhFKA== From: "Masami Hiramatsu (Google)" To: Alexei Starovoitov , Steven Rostedt , Florent Revest Cc: linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Mark Rutland , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: [PATCH v3 01/33] tracing: Add a comment about ftrace_regs definition Date: Mon, 27 Nov 2023 22:53:05 +0900 Message-Id: <170109318538.343914.8426711105240287815.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <170109317214.343914.4784420430328654397.stgit@devnote2> References: <170109317214.343914.4784420430328654397.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu (Google) To clarify what will be expected on ftrace_regs, add a comment to the architecture independent definition of the ftrace_regs. Signed-off-by: Masami Hiramatsu (Google) --- Changes in v3: - Add instruction pointer Changes in v2: - newly added. --- include/linux/ftrace.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index e8921871ef9a..8b48fc621ea0 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -118,6 +118,32 @@ extern int ftrace_enabled; =20 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS =20 +/** + * ftrace_regs - ftrace partial/optimal register set + * + * ftrace_regs represents a group of registers which is used at the + * function entry and exit. There are three types of registers. + * + * - Registers for passing the parameters to callee, including the stack + * pointer. (e.g. rcx, rdx, rdi, rsi, r8, r9 and rsp on x86_64) + * - Registers for passing the return values to caller. + * (e.g. rax and rdx on x86_64) + * - Registers for hooking the function call and return including the + * frame pointer (the frame pointer is architecture/config dependent) + * (e.g. rip, rbp and rsp for x86_64) + * + * Also, architecture dependent fields can be used for internal process. + * (e.g. orig_ax on x86_64) + * + * On the function entry, those registers will be restored except for + * the stack pointer, so that user can change the function parameters + * and instruction pointer (e.g. live patching.) + * On the function exit, only registers which is used for return values + * are restored. + * + * NOTE: user *must not* access regs directly, only do it via APIs, because + * the member can be changed according to the architecture. + */ struct ftrace_regs { struct pt_regs regs; };