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| author | Andrey Konovalov <andreyknvl@google.com> | 2016-10-27 17:46:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-10-27 18:43:42 -0700 |
| commit | b274c0bb394c6a69ac12feac7c2db81f5aff5a55 (patch) | |
| tree | c383709eb747685e42ace2ab17f9b78be6d36045 /kernel/kcov.c | |
| parent | 86d9f48534e800e4d62cdc1b5aaf539f4c1d47d6 (diff) | |
| download | lwn-b274c0bb394c6a69ac12feac7c2db81f5aff5a55.tar.gz lwn-b274c0bb394c6a69ac12feac7c2db81f5aff5a55.zip | |
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.c | 9 |
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) { |