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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62990C433E0 for ; Sat, 11 Jul 2020 01:32:34 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2B74A2075F for ; Sat, 11 Jul 2020 01:32:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="DJZiejK4"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bMfSdxB7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B74A2075F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:To:Subject:Message-ID:Date:From:In-Reply-To: References:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=4zFWFbkiMb8qzNNTrKVqCIua3t8F8kZdSzXXwqEa410=; b=DJZiejK4/yFEZpynzYuc/7Lvw WKD6ktlp/AdyVGjrIB16ld0RI5P09COTOvXLiXbbp071D5c0IZxIuH4jCI+gm+FNeNMLTCI/Fc2bu iRXcKfVBqNKa1UJp7vqDWMtvBIGCA3JxQN11MdPLviUdI4Eqq64zK8gAig34tksE9hnRxF6qiMlu4 6ZZkgKzcxtRv7rpZSvOYZsqPMJLH60vvMLtWZxybJjU5J0Rwv3W0J9WhTuGRtCYpPj4rPDX8Vkoud B9wbYTMbQMiY4z4l7+IKJtJO+GM9DYZ6bT8j15N8b8Iy7HyLYrRX1u9FzIQEYQkOQZUy621ucAyly q5ok4YnIg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ju4NH-0005Sq-Fq; Sat, 11 Jul 2020 01:32:19 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ju4NE-0005SG-86 for linux-riscv@lists.infradead.org; Sat, 11 Jul 2020 01:32:17 +0000 Received: from mail-lj1-f169.google.com (mail-lj1-f169.google.com [209.85.208.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DB22B2075F for ; Sat, 11 Jul 2020 01:32:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594431135; bh=JHAq849TrDR2TO0YVgHnBwsgpBJXggDvOdSCDOO9Mhg=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=bMfSdxB7MrcYqYQa7ldPOwQ86Zvf7PpQlWpXfKwWn1cLEuXE64jZUFUYBu6rYOzyI iW9WNDqwkrk0sgSJttDTT1OJ/ku53mvBNojP8dEQQR8KaZXPa7y6EUoPqUh/FVz9eG YFLH08D+jTSwcQCN2Sb1ues3kIAJ8EMD9qUmzR5A= Received: by mail-lj1-f169.google.com with SMTP id q4so8455724lji.2 for ; Fri, 10 Jul 2020 18:32:14 -0700 (PDT) X-Gm-Message-State: AOAM532Exi973FSKcq+orVXlBSCTv6R4nAAjN4VERI39Dlg83a2h/dE8 nr4RQoiqNZ9IlcDouvgsTO7iVyZuQ50sxbQed5Y= X-Google-Smtp-Source: ABdhPJyp9YYFId4+bHFEau35i4Dd+Jo03McSql50a82wua8FHQxiDnZqzZ8IFMQAFMi/x1kxYJ6SWwlxiHASFRW9a30= X-Received: by 2002:a2e:b0ed:: with SMTP id h13mr31505047ljl.250.1594431133218; Fri, 10 Jul 2020 18:32:13 -0700 (PDT) MIME-Version: 1.0 References: <1594261154-69745-1-git-send-email-guoren@kernel.org> <1594261154-69745-7-git-send-email-guoren@kernel.org> <20200710225017.5ce329485e911f99e17cd483@kernel.org> In-Reply-To: <20200710225017.5ce329485e911f99e17cd483@kernel.org> From: Guo Ren Date: Sat, 11 Jul 2020 09:32:01 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 6/6] riscv: Add KPROBES_ON_FTRACE supported To: Masami Hiramatsu X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200710_213216_744859_F8ACA4E8 X-CRM114-Status: GOOD ( 19.01 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?Q?Patrick_St=C3=A4hlin?= , Guo Ren , Anup Patel , Palmer Dabbelt , Linux Kernel Mailing List , linux-csky@vger.kernel.org, penberg@kernel.org, Atish Patra , Zong Li , Paul Walmsley , Greentime Hu , linux-riscv , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Thx Masami, On Fri, Jul 10, 2020 at 9:50 PM Masami Hiramatsu wrote: > > Hi Guo, > > On Thu, 9 Jul 2020 02:19:14 +0000 > guoren@kernel.org wrote: > > > +/* Ftrace callback handler for kprobes -- called under preepmt disabed */ > > +void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, > > + struct ftrace_ops *ops, struct pt_regs *regs) > > +{ > > + struct kprobe *p; > > + struct kprobe_ctlblk *kcb; > > + > > + p = get_kprobe((kprobe_opcode_t *)ip); > > + if (unlikely(!p) || kprobe_disabled(p)) > > + return; > > + > > + kcb = get_kprobe_ctlblk(); > > + if (kprobe_running()) { > > + kprobes_inc_nmissed_count(p); > > + } else { > > + /* > > + * The regs->epc hasn't been saved by SAVE_ALL in mcount-dyn.S > > + * So no need to resume it, just for kprobe handler. > > + */ > > + instruction_pointer_set(regs, ip); > > + __this_cpu_write(current_kprobe, p); > > + kcb->kprobe_status = KPROBE_HIT_ACTIVE; > > + if (!p->pre_handler || !p->pre_handler(p, regs)) { > > + /* > > + * Emulate singlestep (and also recover regs->pc) > > + * as if there is a nop > > + */ > > + instruction_pointer_set(regs, > > + (unsigned long)p->addr + MCOUNT_INSN_SIZE); > > + if (unlikely(p->post_handler)) { > > + kcb->kprobe_status = KPROBE_HIT_SSDONE; > > + p->post_handler(p, regs, 0); > > + } > > Hmm, don't you need restoring the previous instruction pointer here? look at riscv mcount-dyn.S SAVE_ALL function, sp frame lay out like this: ----------------------- | return address | ----------------------- | frame pointer | ----------------------- | pt_regs x1-x31| ----------------------- It's not a complete pt_regs for the handler, so modifing regs->ip is no use. > If you don't support modifying the instruction pointer in the handler, We can modify ip like this if necessary: *(unsigned long *)((unsigned long)regs + sizeof(struct pt_regs) + 8) = xxx; > it must not be compatible with kprobes. Why, can you show related codes? thank you very much. > > Now BPF function override and function error injection depends on > this behevior, so could you consider to support it in the "ftrace" > implementation at first? (And if it is enabled, you can enable the > livepatch on RISCV too) Great message! But can you show me codes that bpf and err-jnject using the behavior? Thx I'll try to fix up it :) -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/ _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv