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 666D6C433F5 for ; Wed, 20 Apr 2022 18:12:55 +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=ClnYho1AKG6JhuQjd6ES8I+qfjAySBxzTTAAHBaJLmA=; b=hHAB8uBzx9fGlX H1hLKxE+ytFg3SgSxYwZ2PzGLzMC7blhQq4AWeET56/yGwuoYHmAb1/YZmQGvhJyJW+AZ1bKa4Tw8 O/640Lq9OVk0pGFYtn7o1YKVehtSQeX1n9HRFy0CLaemec2o4V4AwU3onwlJXVmcYC+8ynh9Nb29n pFPu7EKDEyC4zJEo4y/aGiK9IXCKNaVQk0yFZJmbCAh+isGYUQvFOY/izXBgRDpvFt4ocN2I7FZy2 iqsYcfgz4ukkJo9zat2sQ+gjri8qBINYR7q6/asLX6y/m3XdJN0L5kUbV48c5zQFRQYUHuhU80IYp HaSZ5tzo5ahKb+sT9U6g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nhEnx-00A1hi-Bz; Wed, 20 Apr 2022 18:11:53 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nhEnu-00A1h6-8w for linux-arm-kernel@lists.infradead.org; Wed, 20 Apr 2022 18:11:52 +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 ams.source.kernel.org (Postfix) with ESMTPS id E8FD6B81EB7; Wed, 20 Apr 2022 18:11:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3CF01C385A0; Wed, 20 Apr 2022 18:11:45 +0000 (UTC) Date: Wed, 20 Apr 2022 14:11:43 -0400 From: Steven Rostedt To: Wang ShaoBo Cc: , , , , , , , , , Subject: Re: [RFC PATCH -next v2 0/4] arm64/ftrace: support dynamic trampoline Message-ID: <20220420141143.23286faa@gandalf.local.home> In-Reply-To: <20220316100132.244849-1-bobo.shaobowang@huawei.com> References: <20220316100132.244849-1-bobo.shaobowang@huawei.com> 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-20220420_111150_664395_5BA05A18 X-CRM114-Status: GOOD ( 18.85 ) 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 Is this going anywhere? -- Steve On Wed, 16 Mar 2022 18:01:28 +0800 Wang ShaoBo wrote: > This implements dynamic trampoline in ARM64, as reference said, we > complete whole design of supporting long jump in dynamic trampoline: > > .text section: > funcA: | funcA(): funcB():| > `-> +-----+ | | ... mov x9 | > | ... | | | adrp <- bl <> | > | nop | | | mov > | nop | | | br x16 ---+ > funcB | nop | | | ftrace_(regs_)caller_tramp: > `-> +-----+ | `--> +---------------------+ > | nop | | | ... | > | nop | | ftrace callsite +---------------------+ > | ... | | `-----> | PLT entry: | > | nop | | | adrp | > | nop | | | add | > funcC: | nop | | ftrace graph callsite | br x16 | > `-> +-----+ | `-----> +---------------------+ > | nop | | | ... | > | nop | | +---------------------+ > > But there is still a tricky problem that is how to adjust tracing ip, > waiting to be solved: > > For ARM64, somecases there may be extra instructions inserted into the > head of tracable functions(but not all) by compiler, for instance BTI[1]. > > This dump vmlinux with CONFIG_BTI=y: > > (1) function gic_handle_irq has bti in its head, so we adjust rec->ip+=5 to last nop > ffffffc0080100e0: d53cd042 mrs x2, tpidr_el2 > ... > ffffffc0080100f0: d503201f nop //__mcount_loc tells the rec->ip > ffffffc0080100f4: d503201f nop > ffffffc0080100f8: d503201f nop > > ffffffc0080100fc : > ffffffc0080100fc: d503245f bti c > ffffffc008010100: d503201f nop > ffffffc008010104: d503201f nop //we adjust origin rec->ip+5 to here > ffffffc008010108: d503233f paciasp > (2) name_to_dev_t.part.0 do not has bti in its head, so we should adjust rec->ip+=4 to last nop > ffff8000080137d4: d503201f nop > ffff8000080137d8: d503201f nop > ffff8000080137dc: d503201f nop > > ffff8000080137e0 : > ffff8000080137e0: d503201f nop > ffff8000080137e4: d503201f nop > ffff8000080137e8: d503233f paciasp > > So at this time we have no idea to identify rec->ip for each tracable function. > > we are looking forward to follow-up discussions. > > References: > [1] https://developer.arm.com/documentation/100076/0100/a64-instruction-set-reference/a64-general-instructions/bti > [2] https://lore.kernel.org/linux-arm-kernel/20200109142736.1122-1-cj.chengjian@huawei.com/ > > Cheng Jian (4): > arm64: introduce aarch64_insn_gen_load_literal > arm64/ftrace: introduce ftrace dynamic trampoline entrances > arm64/ftrace: support dynamically allocated trampolines > arm64/ftrace: implement long jump for dynamic trampolines > > arch/arm64/Makefile | 2 +- > arch/arm64/include/asm/ftrace.h | 10 +- > arch/arm64/include/asm/insn.h | 6 + > arch/arm64/include/asm/module.h | 9 + > arch/arm64/kernel/entry-ftrace.S | 88 ++++++-- > arch/arm64/kernel/ftrace.c | 366 ++++++++++++++++++++++++++++--- > arch/arm64/kernel/module-plts.c | 50 +++++ > arch/arm64/lib/insn.c | 49 +++++ > 8 files changed, 532 insertions(+), 48 deletions(-) > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel