From patchwork Wed Nov 8 14:24:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13450147 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 63F7E19BA8; Wed, 8 Nov 2023 14:24:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="F2uVbebR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37F78C433C9; Wed, 8 Nov 2023 14:24:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699453477; bh=n4E0j8qzABvMFqw3IzKBJQSoLeU/goeaPocNkQ11XcM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F2uVbebRxB1ylSqQ+t2SN5QROmqMPIEbhnk6ue4Qptu9V2AUiYTKdQzHkbX62FwaO u2KyezDq8u4weG+TMuchcAPQh4uxsEjZRCpyq6K/T0QFMONZbq8kiUPhzKCRLwWpiJ dz35a+3226RvbHYlgfR2j6DIEpTtQVBFZ6lYJ3PIup9iWhTMUtfGrFnort9P92eWKI 0QcnS8msS4bdMDUYzVSHyknYYurSNMZ2iCuCZIlX0nEvgCbYI/IfMeTZrdCEj2N6pH sMXig9A9lUqHaREe3hkU3okeoMS+cVg0unevvOSjiZ+2qibn+n3yeAqclnDPdDiDOD srXFhtl+Ifq7Q== 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: [RFC PATCH v2 01/31] tracing: Add a comment about ftrace_regs definition Date: Wed, 8 Nov 2023 23:24:32 +0900 Message-Id: <169945347160.55307.1488323435914144870.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <169945345785.55307.5003201137843449313.stgit@devnote2> References: <169945345785.55307.5003201137843449313.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC 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 v2: - newly added. --- include/linux/ftrace.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index e8921871ef9a..b174af91d8be 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -118,6 +118,31 @@ extern int ftrace_enabled; #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS +/** + * 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 return including the frame pointer + * (the frame pointer is architecture/config dependent) + * (e.g. 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. + * On the function exit, onlu 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; };