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=-10.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,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 B769DC47404 for ; Wed, 9 Oct 2019 13:28:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C55A21848 for ; Wed, 9 Oct 2019 13:28:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="VfC1q4L/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731547AbfJIN2w (ORCPT ); Wed, 9 Oct 2019 09:28:52 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38160 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731178AbfJIN2w (ORCPT ); Wed, 9 Oct 2019 09:28:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=gHIhwkOGTyUWJ1ds4Grb/2Fv2sxTh2+8y7kBcVqDK7w=; b=VfC1q4L/4310KKHZb9OqOufFH QQ7mJVQekbdoXWSyJgQX8loaj7NvL6bmReTPMPBQFcPQHSoL0bJf61mO3r16EEbUpFa3uJdBKfExp laeHtyrKA1tx++/aBnH9QLV6vSGWMnlLa7Y3hQGx72HzH0nQhaJKawPJ6IXKs+3CJFHCRR0URoIrH tknIEAcY4EfpnpFhPH0RnXs0lYzVyz4WckNplk9JgzJtCu1+JBWwY/WQeAHybC4qJvHBfLIq+d0+i jT0M7ZLRTR+ADtlJ86FoR3vJvgurPfbKhjR1oaB5XpQMVSxa5ma+Sxj0ioXy0pEqP2jZOc7K5Rk2j nsWlF0d4g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.2 #3 (Red Hat Linux)) id 1iIC1G-0001XD-5d; Wed, 09 Oct 2019 13:28:46 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 806503008C1; Wed, 9 Oct 2019 15:27:52 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5213A209D5B27; Wed, 9 Oct 2019 15:28:44 +0200 (CEST) Date: Wed, 9 Oct 2019 15:28:44 +0200 From: Peter Zijlstra To: Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Nadav Amit , Andy Lutomirski , Dave Hansen , Song Liu , Steven Rostedt , Daniel Bristot de Oliveira , paulmck@kernel.org Subject: Re: x86/kprobes bug? (was: [PATCH 1/3] x86/alternatives: Teach text_poke_bp() to emulate instructions) Message-ID: <20191009132844.GG2359@hirez.programming.kicks-ass.net> References: <20190827180622.159326993@infradead.org> <20190827181147.053490768@infradead.org> <20191003140050.1d4cf59d3de8b5396d36c269@kernel.org> <20191003082751.GQ4536@hirez.programming.kicks-ass.net> <20191003110106.GI4581@hirez.programming.kicks-ass.net> <20191004224540.766dc0fd824bcd5b8baa2f4c@kernel.org> <20191009130754.GL2311@hirez.programming.kicks-ass.net> <20191009132639.GF2359@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191009132639.GF2359@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 09, 2019 at 03:26:39PM +0200, Peter Zijlstra wrote: > So I suppose I'm suggesting we do something like the below on top of > what I already have here: > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git x86/ftrace > > All it needs are a few comments ;-) Also note how this nicely gets rid > of the one text_poke_bp(.emulate) user, so we can go and remove that as > well. > > --- > arch/x86/include/asm/text-patching.h | 1 + > arch/x86/kernel/alternative.c | 11 ++++++++--- > arch/x86/kernel/kprobes/core.c | 1 + > arch/x86/kernel/kprobes/opt.c | 12 ++++-------- > 4 files changed, 14 insertions(+), 11 deletions(-) > > diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h > index d553175212b3..d3269558e5b5 100644 > --- a/arch/x86/include/asm/text-patching.h > +++ b/arch/x86/include/asm/text-patching.h > @@ -42,6 +42,7 @@ extern void text_poke_early(void *addr, const void *opcode, size_t len); > * an inconsistent instruction while you patch. > */ > extern void *text_poke(void *addr, const void *opcode, size_t len); > +extern void text_poke_sync(void); > extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len); > extern int poke_int3_handler(struct pt_regs *regs); > extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate); > diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c > index 34a08bc68e9a..9e81ab542190 100644 > --- a/arch/x86/kernel/alternative.c > +++ b/arch/x86/kernel/alternative.c > @@ -936,6 +936,11 @@ static void do_sync_core(void *info) > sync_core(); > } > > +void text_poke_sync(void) > +{ > + on_each_cpu(do_sync_core, NULL, 1); > +} > + > struct text_poke_loc { > s32 rel_addr; /* addr := _stext + rel_addr */ > s32 rel32; > @@ -1089,7 +1094,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries > for (i = 0; i < nr_entries; i++) > text_poke(text_poke_addr(&tp[i]), &int3, sizeof(int3)); > > - on_each_cpu(do_sync_core, NULL, 1); > + text_poke_sync(); > > /* > * Second step: update all but the first byte of the patched range. > @@ -1111,7 +1116,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries > * not necessary and we'd be safe even without it. But > * better safe than sorry (plus there's not only Intel). > */ > - on_each_cpu(do_sync_core, NULL, 1); > + text_poke_sync(); > } > > /* > @@ -1127,7 +1132,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries > } > > if (do_sync) > - on_each_cpu(do_sync_core, NULL, 1); > + text_poke_sync(); > > /* > * sync_core() implies an smp_mb() and orders this store against diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 7e4a8a1c9d9a..04858ea7cd76 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -498,11 +498,13 @@ int arch_prepare_kprobe(struct kprobe *p) void arch_arm_kprobe(struct kprobe *p) { text_poke(p->addr, ((unsigned char []){INT3_INSN_OPCODE}), 1); + text_poke_sync(); } void arch_disarm_kprobe(struct kprobe *p) { text_poke(p->addr, &p->opcode, 1); + text_poke_sync(); } void arch_remove_kprobe(struct kprobe *p) > void arch_remove_kprobe(struct kprobe *p) > diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c > index 36d7249f2145..30a2646cfc8a 100644 > --- a/arch/x86/kernel/kprobes/opt.c > +++ b/arch/x86/kernel/kprobes/opt.c > @@ -446,14 +446,10 @@ void arch_optimize_kprobes(struct list_head *oplist) > /* Replace a relative jump with a breakpoint (int3). */ > void arch_unoptimize_kprobe(struct optimized_kprobe *op) > { > - u8 insn_buff[JMP32_INSN_SIZE]; > - > - /* Set int3 to first byte for kprobes */ > - insn_buff[0] = INT3_INSN_OPCODE; > - memcpy(insn_buff + 1, op->optinsn.copied_insn, DISP32_SIZE); > - > - text_poke_bp(op->kp.addr, insn_buff, JMP32_INSN_SIZE, > - text_gen_insn(JMP32_INSN_OPCODE, op->kp.addr, op->optinsn.insn)); > + arch_arm_kprobe(&op->kp); > + text_poke(op->kp.addr + INT3_INSN_SIZE, > + op->optinsn.copied_insn, DISP32_SIZE); > + text_poke_sync(); > } > > /*