From: Andy Lutomirski <luto@kernel.org> To: X86 ML <x86@kernel.org> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Borislav Petkov <bpetkov@suse.de>, Vince Weaver <vincent.weaver@maine.edu>, Andy Lutomirski <luto@kernel.org>, stable@vger.kernel.org Subject: [PATCH 1/2] x86/perf: Fix CR4.PCE propagation to use active_mm instead of mm Date: Thu, 16 Mar 2017 12:59:39 -0700 Message-ID: <0c5b38a76ea50e405f9abe07a13dfaef87c173a1.1489694270.git.luto@kernel.org> (raw) In-Reply-To: <cover.1489694270.git.luto@kernel.org> In-Reply-To: <cover.1489694270.git.luto@kernel.org> If one thread mmaps a perf event while another thread in the same mm is in some context where active_mm != mm (which can happen in the scheduler, for example), refresh_pce() would write the wrong value to CR4.PCE. This broke some PAPI tests. Cc: stable@vger.kernel.org Fixes: 7911d3f7af14 ("perf/x86: Only allow rdpmc if a perf_event is mapped") Reported-and-tested-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 349d4d17aa7f..4f564df73b8f 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2101,8 +2101,8 @@ static int x86_pmu_event_init(struct perf_event *event) static void refresh_pce(void *ignored) { - if (current->mm) - load_mm_cr4(current->mm); + if (current->active_mm) + load_mm_cr4(current->active_mm); } static void x86_pmu_event_mapped(struct perf_event *event) -- 2.9.3
next prev parent reply index Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-16 19:59 [PATCH 0/2] x86/perf: A CR4.PCE bugfix and clarification Andy Lutomirski 2017-03-16 19:59 ` Andy Lutomirski [this message] 2017-03-17 10:16 ` [tip:perf/urgent] x86/perf: Fix CR4.PCE propagation to use active_mm instead of mm tip-bot for Andy Lutomirski 2017-03-16 19:59 ` [PATCH 2/2] x86/perf: Clarify why x86_pmu_event_mapped() isn't racy Andy Lutomirski 2017-03-17 10:17 ` [tip:perf/urgent] " tip-bot for Andy Lutomirski
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=0c5b38a76ea50e405f9abe07a13dfaef87c173a1.1489694270.git.luto@kernel.org \ --to=luto@kernel.org \ --cc=bpetkov@suse.de \ --cc=linux-kernel@vger.kernel.org \ --cc=stable@vger.kernel.org \ --cc=vincent.weaver@maine.edu \ --cc=x86@kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
LKML Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \ linux-kernel@vger.kernel.org public-inbox-index lkml Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel AGPL code for this site: git clone https://public-inbox.org/public-inbox.git