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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 620B8C282DD for ; Tue, 7 Jan 2020 21:21:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 31D512077B for ; Tue, 7 Jan 2020 21:21:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578432075; bh=BDI6/WTSkk2GpBJxGXBqEQbdfqRIM0rGrvfopXGfmMc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WiD2klIzdl1PtF1fDgx43KXWlZe6JOKuvQhon1/TbhC2hArwJ1WIZxJJsWiYJCyoU yEFnBgcpPsmf58Lh24VG/jUhIYtn2x1wbL9NzS9vI/BGIvsW+hMfJ71fVMm5Osfgun SmXAZ+XB1woo+9BVwHKgF38qZ9eeJRHsisdvCbw8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728916AbgAGVDa (ORCPT ); Tue, 7 Jan 2020 16:03:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:45342 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728724AbgAGVD1 (ORCPT ); Tue, 7 Jan 2020 16:03:27 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 126C82077B; Tue, 7 Jan 2020 21:03:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578431005; bh=BDI6/WTSkk2GpBJxGXBqEQbdfqRIM0rGrvfopXGfmMc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kKStGFheJ//jkRIFQVpX4ISKqIM/UMlKBdnMqnFjbkF7qty8mppt0/2YQFHgYhFtq MNV7E13rOQ181kvnH2rSuW785Rfb2NsyYPP2SHGF4LraHF5QbCv5wJMnytxvGA0/y8 gx5l0PX8EbQIR4ZLfa5NqIroqcE+Rcdrfuwg/uP4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Shishkin , "Peter Zijlstra (Intel)" , Jiri Olsa , Vince Weaver , Ingo Molnar , Arnaldo Carvalho de Melo , Sasha Levin Subject: [PATCH 5.4 186/191] perf/x86/intel/bts: Fix the use of page_private() Date: Tue, 7 Jan 2020 21:55:06 +0100 Message-Id: <20200107205342.943849559@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200107205332.984228665@linuxfoundation.org> References: <20200107205332.984228665@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexander Shishkin [ Upstream commit ff61541cc6c1962957758ba433c574b76f588d23 ] Commit 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") brought in a warning with the BTS buffer initialization that is easily tripped with (assuming KPTI is disabled): instantly throwing: > ------------[ cut here ]------------ > WARNING: CPU: 2 PID: 326 at arch/x86/events/intel/bts.c:86 bts_buffer_setup_aux+0x117/0x3d0 > Modules linked in: > CPU: 2 PID: 326 Comm: perf Not tainted 5.4.0-rc8-00291-gceb9e77324fa #904 > RIP: 0010:bts_buffer_setup_aux+0x117/0x3d0 > Call Trace: > rb_alloc_aux+0x339/0x550 > perf_mmap+0x607/0xc70 > mmap_region+0x76b/0xbd0 ... It appears to assume (for lost raisins) that PagePrivate() is set, while later it actually tests for PagePrivate() before using page_private(). Make it consistent and always check PagePrivate() before using page_private(). Fixes: 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Jiri Olsa Cc: Vince Weaver Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Link: https://lkml.kernel.org/r/20191205142853.28894-2-alexander.shishkin@linux.intel.com Signed-off-by: Sasha Levin --- arch/x86/events/intel/bts.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c index 5ee3fed881d3..741540d849f3 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 buf_nr_pages(page) * PAGE_SIZE; } static void * @@ -83,9 +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]); - if (WARN_ON_ONCE(!PagePrivate(page) && nr_pages > 1)) - return NULL; - pg += 1 << page_private(page); + pg += buf_nr_pages(page); nbuf++; } @@ -109,7 +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); -- 2.20.1