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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 CC971C4338F for ; Wed, 11 Aug 2021 07:51:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB4D360EB5 for ; Wed, 11 Aug 2021 07:51:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235731AbhHKHve (ORCPT ); Wed, 11 Aug 2021 03:51:34 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:13263 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235092AbhHKHvd (ORCPT ); Wed, 11 Aug 2021 03:51:33 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Gl27K4lcmz1CV4S; Wed, 11 Aug 2021 15:50:53 +0800 (CST) Received: from dggema757-chm.china.huawei.com (10.1.198.199) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Wed, 11 Aug 2021 15:51:08 +0800 Received: from [127.0.0.1] (10.69.38.203) by dggema757-chm.china.huawei.com (10.1.198.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Wed, 11 Aug 2021 15:51:07 +0800 Subject: Re: [PATCH v3 2/2] arm64: kprobe: Enable OPTPROBE for arm64 To: Masami Hiramatsu , Linuxarm CC: , , , , , , , , , , References: <20210810055330.18924-1-liuqi115@huawei.com> <20210810055330.18924-3-liuqi115@huawei.com> <20210811162004.9b3349e6bda68e74e0a3a4ad@kernel.org> From: "liuqi (BA)" Message-ID: Date: Wed, 11 Aug 2021 15:51:07 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20210811162004.9b3349e6bda68e74e0a3a4ad@kernel.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.38.203] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggema757-chm.china.huawei.com (10.1.198.199) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Masmi, On 2021/8/11 15:20, Masami Hiramatsu wrote: > Hi Qi, > > Thanks for updating. > > On Tue, 10 Aug 2021 13:53:30 +0800 > Qi Liu wrote: > [...] >> +void arch_optimize_kprobes(struct list_head *oplist) >> +{ >> + struct optimized_kprobe *op, *tmp; >> + >> + list_for_each_entry_safe(op, tmp, oplist, list) { >> + u32 insn; >> + >> + WARN_ON(kprobe_disabled(&op->kp)); >> + >> + /* >> + * Backup instructions which will be replaced >> + * by jump address >> + */ >> + memcpy(op->optinsn.copied_insn, op->kp.addr, >> + RELATIVEJUMP_SIZE); >> + insn = aarch64_insn_gen_branch_imm((unsigned long)op->kp.addr, >> + (unsigned long)op->optinsn.insn, >> + AARCH64_INSN_BRANCH_NOLINK); >> + >> + WARN_ON(insn == 0); >> + >> + aarch64_insn_patch_text((void *)&(op->kp.addr), &insn, 1); > > Can you also reduce the number of aarch64_insn_patch_text() here? > Since arch_optimize_kprobes() running in the workqueue context, you can > allocate memory. Thus, you can do something like this(not cleaned) > > #define OPTPROBE_BATCH_SIZE 64 > > void arch_optimize_kprobes(struct list_head *oplist) > { > struct optimized_kprobe *op, *tmp; > void **addrs; > u32 *insns; > int i = 0; > > addrs = kcalloc(OPTPROBE_BATCH_SIZE, sizeof(*addrs), GFP_KERNEL); > insns = kcalloc(OPTPROBE_BATCH_SIZE, sizeof(*insns), GFP_KERNEL); > > list_for_each_entry_safe(op, tmp, oplist, list) { > memcpy(op->optinsn.copied_insn, op->kp.addr, > RELATIVEJUMP_SIZE); > addrs[i] = op->kp.addr; > insns[i] = aarch64_insn_gen_branch_imm((unsigned long)op->kp.addr, > (unsigned long)op->optinsn.insn, > AARCH64_INSN_BRANCH_NOLINK); > list_del_init(&op->list); > if (++i == OPTPROBE_BATCH_SIZE) > break; > } > aarch64_insn_patch_text(addrs, insns, i); > > kfree(addrs); > kfree(insns); > } > > Since the stop_machine() penalty is heavier than you think (especially, > if the machine has many cores), it must be avoided as much as possible. > got it, I'll fix this next time. > >> + >> + list_del_init(&op->list); >> + } >> +} >> + >> +void arch_unoptimize_kprobe(struct optimized_kprobe *op) >> +{ >> + arch_arm_kprobe(&op->kp); >> +} >> + >> +/* >> + * Recover original instructions and breakpoints from relative jumps. >> + * Caller must call with locking kprobe_mutex. >> + */ >> +void arch_unoptimize_kprobes(struct list_head *oplist, >> + struct list_head *done_list) >> +{ >> + struct optimized_kprobe *op, *tmp; >> + >> + list_for_each_entry_safe(op, tmp, oplist, list) { >> + arch_unoptimize_kprobe(op); >> + list_move(&op->list, done_list); >> + } >> +} > > Ditto. > You don't need to use arch_arm_kprobe() in this case. > > Thank you, > thanks, will change this next time. Qi >> + >> +void arch_remove_optimized_kprobe(struct optimized_kprobe *op) >> +{ >> + if (op->optinsn.insn) { >> + free_optinsn_slot(op->optinsn.insn, 1); >> + op->optinsn.insn = NULL; >> + } >> +} >> diff --git a/arch/arm64/kernel/probes/optprobe_trampoline.S b/arch/arm64/kernel/probes/optprobe_trampoline.S >> new file mode 100644 >> index 000000000000..24d713d400cd >> --- /dev/null >> +++ b/arch/arm64/kernel/probes/optprobe_trampoline.S >> @@ -0,0 +1,37 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * trampoline entry and return code for optprobes. >> + */ >> + >> +#include >> +#include >> +#include >> + >> + .global optprobe_template_entry >> +optprobe_template_entry: >> + sub sp, sp, #PT_REGS_SIZE >> + save_all_base_regs >> + /* Get parameters to optimized_callback() */ >> + ldr x0, 1f >> + mov x1, sp >> + /* Branch to optimized_callback() */ >> + .global optprobe_template_call >> +optprobe_template_call: >> + nop >> + restore_all_base_regs >> + ldr lr, [sp, #S_LR] >> + add sp, sp, #PT_REGS_SIZE >> + .global optprobe_template_restore_orig_insn >> +optprobe_template_restore_orig_insn: >> + nop >> + .global optprobe_template_restore_end >> +optprobe_template_restore_end: >> + nop >> + .global optprobe_template_end >> +optprobe_template_end: >> + .global optprobe_template_val >> +optprobe_template_val: >> + 1: .long 0 >> + .long 0 >> + .global optprobe_template_max_length >> +optprobe_template_max_length: >> -- >> 2.17.1 >> > >