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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>
This commit is contained in:
Andrey Konovalov 2016-10-27 17:46:21 -07:00 committed by Linus Torvalds
parent 86d9f48534
commit b274c0bb39
1 changed files with 8 additions and 1 deletions
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9
kernel/kcov.c
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@ -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) {