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authorAndrey Konovalov <andreyknvl@google.com>2016-10-27 17:46:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-27 18:43:42 -0700
commitb274c0bb394c6a69ac12feac7c2db81f5aff5a55 (patch)
treec383709eb747685e42ace2ab17f9b78be6d36045 /kernel/kcov.c
parent86d9f48534e800e4d62cdc1b5aaf539f4c1d47d6 (diff)
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kcov: properly check if we are in an interrupt
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(). As a result of this change, kcov will start to collect coverage from within local_bh_disable()/local_bh_enable() sections. Link: http://lkml.kernel.org/r/1476115803-20712-1-git-send-email-andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Nicolai Stange <nicstange@gmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Kees Cook <keescook@chromium.org> Cc: James Morse <james.morse@arm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/kcov.c')
-rw-r--r--kernel/kcov.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/kernel/kcov.c b/kernel/kcov.c
index 8d44b3fea9d0..30e6d05aa5a9 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) {