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=-1.0 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS 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 ED1C6C46460 for ; Thu, 9 Aug 2018 12:03:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7D042150A for ; Thu, 9 Aug 2018 12:03:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7D042150A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732036AbeHIO1z (ORCPT ); Thu, 9 Aug 2018 10:27:55 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:48516 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730261AbeHIO1y (ORCPT ); Thu, 9 Aug 2018 10:27:54 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1063C83221; Thu, 9 Aug 2018 12:03:20 +0000 (UTC) Received: from krava.brq.redhat.com (unknown [10.43.17.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5300C10B7C95; Thu, 9 Aug 2018 12:03:18 +0000 (UTC) From: Jiri Olsa To: Arnaldo Carvalho de Melo Cc: lkml , Ingo Molnar , Namhyung Kim , David Ahern , Alexander Shishkin , Peter Zijlstra , Milind Chabbi , Oleg Nesterov , Frederic Weisbecker Subject: [PATCH 5/5] perf/hw_breakpoint: Add fallback code for ptrace_set_breakpoint_addr Date: Thu, 9 Aug 2018 14:03:05 +0200 Message-Id: <20180809120305.20693-6-jolsa@kernel.org> In-Reply-To: <20180809120305.20693-1-jolsa@kernel.org> References: <20180809120305.20693-1-jolsa@kernel.org> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Thu, 09 Aug 2018 12:03:20 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Thu, 09 Aug 2018 12:03:20 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jolsa@kernel.org' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Restoring the breakpoint after unsuccesfull address change, so following user code no longer produces disabled breakpoint. ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[0]), addr_1) ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[7]), dr7) ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[0]), -1) The first 2 ptrace calls set breakpoint on addr_1. The 3rd ptrace call tries to set it to bogus address (-1). This would normaly end up with disabled breakpoint. This patch adds the code that restores the breakpoint to its original state. Link: http://lkml.kernel.org/n/tip-h9ut835vl297roen0v163zg6@git.kernel.org Signed-off-by: Jiri Olsa --- arch/x86/kernel/ptrace.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index e2ee403865eb..22c06d0a38d1 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -693,9 +693,14 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, t->ptrace_bps[nr] = bp; } else { struct perf_event_attr attr = bp->attr; + bool disabled = attr.disabled; attr.bp_addr = addr; err = modify_user_hw_breakpoint(bp, &attr); + if (err && !disabled) { + bp->attr.disabled = false; + WARN_ON(modify_user_hw_breakpoint(bp, &bp->attr)); + } } return err; -- 2.17.1