From: James Morse <>

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 <>
Acked-by: Dmitry Vyukov <>
Cc: Alexander Potapenko <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>

(cherry picked from commit bdab42dfc974d15303afbf259f340f374a453974)
Signed-off-by: Andrey Ryabinin <>
 kernel/kcov.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kcov.c b/kernel/kcov.c
index 9ea7a05..f963fca 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -44,7 +44,7 @@ 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;

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