From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753070AbcJJQTU (ORCPT ); Mon, 10 Oct 2016 12:19:20 -0400 Received: from mail-qk0-f171.google.com ([209.85.220.171]:32955 "EHLO mail-qk0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752793AbcJJQTT (ORCPT ); Mon, 10 Oct 2016 12:19:19 -0400 From: Andrey Konovalov To: Andrew Morton , Dmitry Vyukov , Nicolai Stange , Andrey Ryabinin , Kees Cook , James Morse , linux-kernel@vger.kernel.org, vegard.nossum@oracle.com, quentin.casasnovas@oracle.com, ryabinin.a.a@gmail.com Cc: Andrey Konovalov Subject: [PATCH v2] kcov: properly check if we are in an interrupt Date: Mon, 10 Oct 2016 18:10:03 +0200 Message-Id: <1476115803-20712-1-git-send-email-andreyknvl@google.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org in_interrupt() returns a nonzero value when we are either in an interrupt or have bh disabled via local_bh_disable(). Since we are interested in only ignoring coverage from actual interrupts, do a proper check instead of just calling in_interrupt(). Signed-off-by: Andrey Konovalov --- Changes in v2: - Add a comment explaining why the check is open-coded. kernel/kcov.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/kcov.c b/kernel/kcov.c index 8d44b3f..30e6d05 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -53,8 +53,15 @@ void notrace __sanitizer_cov_trace_pc(void) /* * We are interested in code coverage as a function of a syscall inputs, * so we ignore code executed in interrupts. + * The checks for whether we are in an interrupt are open-coded, because + * 1. We can't use in_interrupt() here, since it also returns true + * when we are inside local_bh_disable() section. + * 2. We don't want to use (in_irq() | in_serving_softirq() | in_nmi()), + * since that leads to slower generated code (three separate tests, + * one for each of the flags). */ - if (!t || in_interrupt()) + if (!t || (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_OFFSET + | NMI_MASK))) return; mode = READ_ONCE(t->kcov_mode); if (mode == KCOV_MODE_TRACE) { -- 2.8.0.rc3.226.g39d4020