[PATCH v2 4/4] x86: Ignore stack unwinding in KCOV

[Dmitry Vyukov <dvyukov@google.com>]

Stack unwinding produces large amounts of uninteresting coverage.
It's called from KASAN kmalloc/kfree hooks, fault injection, etc.
It's not particularly useful and is not a function of system call args.
Ignore that code.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: syzkaller@googlegroups.com
---
 arch/x86/kernel/Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 20a0dd51700a..cd49ebfae984 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -39,6 +39,14 @@ KMSAN_SANITIZE_sev.o					:= n
 # first second.
 KCOV_INSTRUMENT_head$(BITS).o				:= n
 KCOV_INSTRUMENT_sev.o					:= n
+# These are called from save_stack_trace() on debug paths,
+# and produce large amounts of uninteresting coverage.
+KCOV_INSTRUMENT_stacktrace.o				:= n
+KCOV_INSTRUMENT_dumpstack.o				:= n
+KCOV_INSTRUMENT_dumpstack_$(BITS).o			:= n
+KCOV_INSTRUMENT_unwind_orc.o				:= n
+KCOV_INSTRUMENT_unwind_frame.o				:= n
+KCOV_INSTRUMENT_unwind_guess.o				:= n
 
 CFLAGS_irq.o := -I $(src)/../include/asm/trace
 
-- 
2.45.2.505.gda0bf45e8d-goog