Commit 99463c81 authored May 08, 2017 by Dmitry Vyukov Committed by Paul Lawrence Dec 18, 2017

UPSTREAM: kcov: simplify interrupt check

in_interrupt() semantics are confusing and wrong for most users as it
also returns true when bh is disabled.  Thus we open coded a proper
check for interrupts in __sanitizer_cov_trace_pc() with a lengthy
explanatory comment.

Use the new in_task() predicate instead.

Link: http://lkml.kernel.org/r/20170321091026.139655-1-dvyukov@google.com


Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: James Morse <james.morse@arm.com>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Bug: 64145065
(cherry-picked from f61e869d519c0c11a8d80a503cfdfb4897df855a)
Change-Id: Ice260535314238c8f82ddc578ecaeea6177d28fc
Signed-off-by: Paul Lawrence <paullawrence@google.com>

parent 5fc77d00

kernel/kcov.c

+1 −8

Original line number	Diff line number	Diff line
		@@ -60,15 +60,8 @@ 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 \|\| (preempt_count() & (HARDIRQ_MASK \| SOFTIRQ_OFFSET
		\| NMI_MASK)))
		if (!t \|\| !in_task())
		return;
		mode = READ_ONCE(t->kcov_mode);
		if (mode == KCOV_MODE_TRACE) {