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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 E682AC43603 for ; Thu, 5 Dec 2019 14:29:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1D2E24651 for ; Thu, 5 Dec 2019 14:29:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729633AbfLEO3G (ORCPT ); Thu, 5 Dec 2019 09:29:06 -0500 Received: from mga18.intel.com ([134.134.136.126]:12291 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729530AbfLEO3C (ORCPT ); Thu, 5 Dec 2019 09:29:02 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Dec 2019 06:29:02 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,281,1571727600"; d="scan'208";a="209170931" Received: from black.fi.intel.com (HELO black.fi.intel.com.) ([10.237.72.28]) by fmsmga007.fm.intel.com with ESMTP; 05 Dec 2019 06:29:00 -0800 From: Alexander Shishkin To: Peter Zijlstra Cc: Arnaldo Carvalho de Melo , Ingo Molnar , linux-kernel@vger.kernel.org, Jiri Olsa , Alexander Shishkin Subject: [PATCH 2/2] perf/x86/intel/bts: Fix the use of page_private() Date: Thu, 5 Dec 2019 17:28:53 +0300 Message-Id: <20191205142853.28894-3-alexander.shishkin@linux.intel.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191205142853.28894-1-alexander.shishkin@linux.intel.com> References: <20191205142853.28894-1-alexander.shishkin@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") uses page_private(page) without checking the PagePrivate(page) first, which seems like a potential bug, considering that page->private aliases with other stuff in struct page. Fix this by checking PagePrivate() first. Signed-off-by: Alexander Shishkin Fixes: 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") --- arch/x86/events/intel/bts.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c index d53b4fb86d87..9e4da1c5a129 100644 --- a/arch/x86/events/intel/bts.c +++ b/arch/x86/events/intel/bts.c @@ -63,9 +63,17 @@ struct bts_buffer { static struct pmu bts_pmu; +static int buf_nr_pages(struct page *page) +{ + if (!PagePrivate(page)) + return 1; + + return 1 << page_private(page); +} + static size_t buf_size(struct page *page) { - return 1 << (PAGE_SHIFT + page_private(page)); + return 1 << (PAGE_SHIFT + buf_nr_pages(page)); } static void * @@ -83,7 +91,7 @@ bts_buffer_setup_aux(struct perf_event *event, void **pages, /* count all the high order buffers */ for (pg = 0, nbuf = 0; pg < nr_pages;) { page = virt_to_page(pages[pg]); - pg += 1 << page_private(page); + pg += buf_nr_pages(page); nbuf++; } @@ -107,7 +115,7 @@ bts_buffer_setup_aux(struct perf_event *event, void **pages, unsigned int __nr_pages; page = virt_to_page(pages[pg]); - __nr_pages = PagePrivate(page) ? 1 << page_private(page) : 1; + __nr_pages = buf_nr_pages(page); buf->buf[nbuf].page = page; buf->buf[nbuf].offset = offset; buf->buf[nbuf].displacement = (pad ? BTS_RECORD_SIZE - pad : 0); -- 2.24.0