From nobody Thu Apr 2 14:41:08 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76359C6FA82 for ; Fri, 23 Sep 2022 08:51:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230387AbiIWIvQ (ORCPT ); Fri, 23 Sep 2022 04:51:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230487AbiIWIu5 (ORCPT ); Fri, 23 Sep 2022 04:50:57 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47CF8126B7E; Fri, 23 Sep 2022 01:50:55 -0700 (PDT) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MYm4j0QwHzpT3m; Fri, 23 Sep 2022 16:47:49 +0800 (CST) Received: from huawei.com (10.67.174.53) by kwepemi500012.china.huawei.com (7.221.188.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 23 Sep 2022 16:50:39 +0800 From: Liao Chang To: , , , , , , , , , , , CC: , , , Subject: [PATCH 1/3] riscv/kprobe: Optimize the performance of patching single-step slot Date: Fri, 23 Sep 2022 16:46:56 +0800 Message-ID: <20220923084658.99304-2-liaochang1@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220923084658.99304-1-liaochang1@huawei.com> References: <20220923084658.99304-1-liaochang1@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.53] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemi500012.china.huawei.com (7.221.188.12) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Single-step slot would not be used until kprobe is enabled, that means no race condition occurs on it under SMP, hence it is safe to pacth ss slot without stopping machine. Acked-by: Masami Hiramatsu (Google) Signed-off-by: Liao Chang --- arch/riscv/kernel/probes/kprobes.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/= kprobes.c index e6e950b7cf32..bc1f39b96e41 100644 --- a/arch/riscv/kernel/probes/kprobes.c +++ b/arch/riscv/kernel/probes/kprobes.c @@ -24,12 +24,14 @@ post_kprobe_handler(struct kprobe *, struct kprobe_ctlb= lk *, struct pt_regs *); static void __kprobes arch_prepare_ss_slot(struct kprobe *p) { unsigned long offset =3D GET_INSN_LENGTH(p->opcode); + kprobe_opcode_t slot[MAX_INSN_SIZE]; =20 p->ainsn.api.restore =3D (unsigned long)p->addr + offset; =20 - patch_text(p->ainsn.api.insn, p->opcode); - patch_text((void *)((unsigned long)(p->ainsn.api.insn) + offset), - __BUG_INSN_32); + memcpy(slot, &p->opcode, offset); + *(kprobe_opcode_t *)((unsigned long)slot + offset) =3D __BUG_INSN_32; + patch_text_nosync(p->ainsn.api.insn, slot, + offset + GET_INSN_LENGTH(__BUG_INSN_32)); } =20 static void __kprobes arch_prepare_simulate(struct kprobe *p) --=20 2.17.1