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UPSTREAM: kcov: don't trace the code coverage code

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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>

Bug: 64145065
(cherry-picked from bdab42dfc9)
Change-Id: If7708ca761f81e0645d709b263e61493fc016e01
Signed-off-by: Paul Lawrence <paullawrence@google.com>
This commit is contained in:
James Morse 2016-04-28 16:18:52 -07:00 committed by Amit Pundir
parent 8c8a5ee21a
commit 318c10553b
1 changed files with 1 additions and 1 deletions
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2
kernel/kcov.c
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@ -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;