From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B5DCFC433EF for ; Wed, 11 May 2022 15:16:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=K+nj7ij2B4PEzJLrzaSaVNSRbXPPYtyFmON4VtrlTc4=; b=0DHeS/+toue1H+ UK3mEKbvM/9RjzNnc7w0T2HwnnbDHbYWllMb5lCncdn7sqbYVgSxrXXQCogqIjMFcG5TPKdiFpv+4 x70GE+hMXztmphZHpl+Xu0YMvU/cXbnBgrJtV2OZGPXtO7rf4N309K1v0U3VQ+RRBdoVFMHrJ4FCV CzzxvNEEWjBNhZy7dzCVWVGwRSdMugM/0UaOXcchyza5GvclmryUn+56SZY6a9KxUrPWR4+6l5qS1 FgRZ7gRZw3zmrVZY6t6SNELEApYftA2y1ScjkXLh+KOLk1DTSGfrGAYG0j8yzWvgIpQLBeH/Pf6xZ ZKUDGrYCPzZ2Ie+h//yg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1noo3N-007Tg1-LU; Wed, 11 May 2022 15:15:05 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1noo0a-007SOi-PO for linux-arm-kernel@lists.infradead.org; Wed, 11 May 2022 15:12:15 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5C19861868; Wed, 11 May 2022 15:12:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6AB63C340EE; Wed, 11 May 2022 15:12:09 +0000 (UTC) Date: Wed, 11 May 2022 11:12:07 -0400 From: Steven Rostedt To: Masami Hiramatsu Cc: Mark Rutland , Wang ShaoBo , cj.chengjian@huawei.com, huawei.libin@huawei.com, xiexiuqi@huawei.com, liwei391@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, zengshun.wu@outlook.com, Jiri Olsa Subject: Re: [RFC PATCH -next v2 3/4] arm64/ftrace: support dynamically allocated trampolines Message-ID: <20220511111207.25d1a693@gandalf.local.home> In-Reply-To: <20220511233450.40136cdf6a53eb32cd825be8@kernel.org> References: <20220421100639.03c0d123@gandalf.local.home> <20220421114201.21228eeb@gandalf.local.home> <20220421130648.56b21951@gandalf.local.home> <20220422114541.34d71ad9@gandalf.local.home> <20220426174749.b5372c5769af7bf901649a05@kernel.org> <20220505121538.04773ac98e2a8ba17f675d39@kernel.org> <20220509142203.6c4f2913@gandalf.local.home> <20220510181012.d5cba23a2547f14d14f016b9@kernel.org> <20220510104446.6d23b596@gandalf.local.home> <20220511233450.40136cdf6a53eb32cd825be8@kernel.org> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220511_081212_924726_1C88A483 X-CRM114-Status: GOOD ( 15.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 11 May 2022 23:34:50 +0900 Masami Hiramatsu wrote: > OK, so fregs::regs will have a subset of pt_regs, and accessibility of > the registers depends on the architecture. If we can have a checker like > > ftrace_regs_exist(fregs, reg_offset) Or something. I'd have to see the use case. > > kprobe on ftrace or fprobe user (BPF) can filter user's requests. > I think I can introduce a flag for kprobes so that user can make a > kprobe handler only using a subset of registers. > Maybe similar filter code is also needed for BPF 'user space' library > because this check must be done when compiling BPF. Is there any other case without full regs that the user would want anything other than the args, stack pointer and instruction pointer? That is, have a flag that says "only_args" or something, that says they will only get the registers for arguments, a stack pointer, and the instruction pointer (note, the fregs may not have the instruction pointer as that is passed to the the caller via the "ip" parameter. If the fregs needs that, we can add a "ftrace_regs_set_ip()" before calling the callback registered to the fprobe). -- Steve _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel