The patch titled
Subject: kcov: properly check if we are in an interrupt
has been added to the -mm tree. Its filename is
kcov-properly-check-if-we-are-in-an-interrupt.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kcov-properly-check-if-we-are-in-an-interrupt.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kcov-properly-check-if-we-are-in-an-interrupt.patch
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: 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().
Link: http://lkml.kernel.org/r/1476115803-20712-1-git-send-email-andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Nicolai Stange <nicstange@xxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kcov.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff -puN kernel/kcov.c~kcov-properly-check-if-we-are-in-an-interrupt kernel/kcov.c
--- a/kernel/kcov.c~kcov-properly-check-if-we-are-in-an-interrupt
+++ a/kernel/kcov.c
@@ -53,8 +53,15 @@ void notrace __sanitizer_cov_trace_pc(vo
/*
* 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) {
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kcov-properly-check-if-we-are-in-an-interrupt.patch
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