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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9EE20C43332 for ; Tue, 2 Mar 2021 15:16:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C7B160200 for ; Tue, 2 Mar 2021 15:16:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1574267AbhCBPOs (ORCPT ); Tue, 2 Mar 2021 10:14:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:57186 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1447312AbhCBMwL (ORCPT ); Tue, 2 Mar 2021 07:52:11 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A196261606; Tue, 2 Mar 2021 12:51:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614689488; bh=cLGqDIf77u6TyKAWg+j9rtHNr24QDQWpZ4UWpzj0/s0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kN9VxKlKEhMJKdpj3QsdnfktbriGFjxGvJWL2oIJ5yVYt3tZD6sR/ilWHwrRGDP0f c3ICCpKgrmU78gp6ZaGYiibLWCTug3xsm21cgpJSx2yEu+2U7HVGN7G7Uqx3ksSB/7 gDWpZjmVpuDIKLC5mkkkbPE3fDmTgF9cEym++ozXnmxJhLu6SbUa4/0c0TCWpxWqEt 99SRz1r3udcrkRzZRA0ZzVGQboa/gmZb6GVRER3r4buCh+Xhl0DGCSLpxvmXjSm8Fu DilgBmCVt/YUPfoXr+V082BaQmIpc7wVaIwPpoLm5naq+0pc1Bs6VzwB4TBVOrocsI tMgOR+PpZJcxA== Date: Tue, 2 Mar 2021 21:51:24 +0900 From: Masami Hiramatsu To: Peter Zijlstra Cc: Andy Lutomirski , Ingo Molnar , Oleg Nesterov , LKML , Anil S Keshavamurthy , "David S . Miller" , X86 ML , Andrew Cooper , Steven Rostedt Subject: Re: [RFC PATCH 1/1] x86/kprobes: Use int3 instead of debug trap for single-step Message-Id: <20210302215124.2614a36fdf084d514dabfc4d@kernel.org> In-Reply-To: References: <161460768474.430263.18425867006584111900.stgit@devnote2> <161460769556.430263.12936080446789384938.stgit@devnote2> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2 Mar 2021 09:54:43 +0100 Peter Zijlstra wrote: > On Tue, Mar 02, 2021 at 09:41:32AM +0100, Peter Zijlstra wrote: > > > Aside of a few nits: > > something like so.. Thanks Peter, I completely agree with that change! Let me update the patch. > > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -457,13 +457,20 @@ static void kprobe_emulate_call(struct k > } > NOKPROBE_SYMBOL(kprobe_emulate_call); > > -static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs) > +static __always_inline > +void __kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs, bool cond) > { > unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; > > - ip += p->ainsn.rel32; > + if (cond) > + ip += p->ainsn.rel32; > int3_emulate_jmp(regs, ip); > } > + > +static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs) > +{ > + __kprobe_emulate_jmp(p, regs, true); > +} > NOKPROBE_SYMBOL(kprobe_emulate_jmp); > > static const unsigned long jcc_mask[6] = { > @@ -488,10 +495,7 @@ static void kprobe_emulate_jcc(struct kp > if (p->ainsn.jcc.type >= 0xe) > match = match && (regs->flags & X86_EFLAGS_ZF); > } > - if ((match && !invert) || (!match && invert)) > - kprobe_emulate_jmp(p, regs); > - else > - regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; > + __kprobe_emulate_jmp(p, regs, (match && !invert) || (!match && invert)); > } > NOKPROBE_SYMBOL(kprobe_emulate_jcc); > > @@ -524,10 +528,7 @@ static void kprobe_emulate_loop(struct k > else if (p->ainsn.loop.type == 1) /* LOOPE */ > match = match && (regs->flags & X86_EFLAGS_ZF); > > - if (match) > - kprobe_emulate_jmp(p, regs); > - else > - regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; > + __kprobe_emulate_jmp(p, regs, match); > } > NOKPROBE_SYMBOL(kprobe_emulate_loop); > > @@ -613,6 +614,12 @@ static int prepare_emulation(struct kpro > else > p->ainsn.rel32 = *(s32 *)&insn->immediate.value; > break; > + case 0x70 ... 0x7f: > + /* 1 byte conditional jump */ > + p->ainsn.emulate_op = kprobe_emulate_jcc; > + p->ainsn.jcc.type = opcode & 0xf; > + p->ainsn.rel32 = *(char *)insn->immediate.bytes; > + break; > case 0x0f: > opcode = insn->opcode.bytes[1]; > if ((opcode & 0xf0) == 0x80) { > @@ -667,12 +674,7 @@ static int prepare_emulation(struct kpro > #endif > break; > default: > - if ((opcode & 0xf0) == 0x70) { > - /* 1 byte conditional jump */ > - p->ainsn.emulate_op = kprobe_emulate_jcc; > - p->ainsn.jcc.type = opcode & 0xf; > - p->ainsn.rel32 = *(char *)insn->immediate.bytes; > - } > + break; > } > p->ainsn.size = insn->length; > -- Masami Hiramatsu