Commit bdab42df authored Apr 28, 2016 by James Morse Committed by Linus Torvalds Apr 28, 2016

kcov: don't trace the code coverage code



Kcov causes the compiler to add a call to __sanitizer_cov_trace_pc() in
every basic block.  Ftrace patches in a call to _mcount() to each
function it has annotated.

Letting these mechanisms annotate each other is a bad thing.  Break the
loop by adding 'notrace' to __sanitizer_cov_trace_pc() so that ftrace
won't try to patch this code.

This patch lets arm64 with KCOV and STACK_TRACER boot.

Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent fd901c95

kernel/kcov.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -43,7 +43,7 @@ struct kcov {
		* Entry point from instrumented code.
		* This is called once per basic-block/edge.
		*/
		void __sanitizer_cov_trace_pc(void)
		void notrace __sanitizer_cov_trace_pc(void)
		{
		struct task_struct *t;
		enum kcov_mode mode;