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 47476C46464 for ; Thu, 9 Aug 2018 12:03:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 06DF62150A for ; Thu, 9 Aug 2018 12:03:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06DF62150A 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 S1731205AbeHIO1t (ORCPT ); Thu, 9 Aug 2018 10:27:49 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47154 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730261AbeHIO1s (ORCPT ); Thu, 9 Aug 2018 10:27:48 -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 2061C7A7EE; Thu, 9 Aug 2018 12:03:14 +0000 (UTC) Received: from krava.brq.redhat.com (unknown [10.43.17.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6475410B7C95; Thu, 9 Aug 2018 12:03:12 +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 2/5] perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set Date: Thu, 9 Aug 2018 14:03:02 +0200 Message-Id: <20180809120305.20693-3-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 [10.11.55.2]); Thu, 09 Aug 2018 12:03:14 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Thu, 09 Aug 2018 12:03:14 +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 We need to change the breakpoint even if the attr with new fields has disabled set to true. Current code prevents following user code to change the breakpoint address: ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[0]), addr_1) ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[0]), addr_2) ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[7]), dr7) The first PTRACE_POKEUSER creates the breakpoint with attr.disabled set to true: ptrace_set_breakpoint_addr(nr = 0) struct perf_event *bp = t->ptrace_bps[nr]; ptrace_register_breakpoint(..., disabled = true) ptrace_fill_bp_fields(..., disabled) register_user_hw_breakpoint So the second PTRACE_POKEUSER will be omitted: ptrace_set_breakpoint_addr(nr = 0) struct perf_event *bp = t->ptrace_bps[nr]; struct perf_event_attr attr = bp->attr; modify_user_hw_breakpoint(bp, &attr) if (!attr->disabled) modify_user_hw_breakpoint_check Acked-by: Oleg Nesterov Reported-by: Milind Chabbi Link: http://lkml.kernel.org/n/tip-yjhgplc28gk5gfzt7ceooe6z@git.kernel.org Signed-off-by: Jiri Olsa --- kernel/events/hw_breakpoint.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index b3814fce5ecb..fb229d9c7f3c 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -509,6 +509,8 @@ modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *a */ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) { + int err; + /* * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it * will not be possible to raise IPIs that invoke __perf_event_disable. @@ -520,11 +522,11 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att else perf_event_disable(bp); - if (!attr->disabled) { - int err = modify_user_hw_breakpoint_check(bp, attr, false); + err = modify_user_hw_breakpoint_check(bp, attr, false); + if (err) + return err; - if (err) - return err; + if (!attr->disabled) { perf_event_enable(bp); bp->attr.disabled = 0; } -- 2.17.1