From 43e76af85fa7e75ac9b71fc2fcc250abb1889bff Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Thu, 30 Jan 2020 22:17:35 -0800 Subject: [PATCH] kcov: ignore fault-inject and stacktrace Don't instrument 3 more files that contain debugging facilities and produce large amounts of uninteresting coverage for every syscall. The following snippets are sprinkled all over the place in kcov traces in a debugging kernel. We already try to disable instrumentation of stack unwinding code and of most debug facilities. I guess we did not use fault-inject.c at the time, and stacktrace.c was somehow missed (or something has changed in kernel/configs). This change both speeds up kcov (kernel doesn't need to store these PCs, user-space doesn't need to process them) and frees trace buffer capacity for more useful coverage. should_fail lib/fault-inject.c:149 fail_dump lib/fault-inject.c:45 stack_trace_save kernel/stacktrace.c:124 stack_trace_consume_entry kernel/stacktrace.c:86 stack_trace_consume_entry kernel/stacktrace.c:89 ... a hundred frames skipped ... stack_trace_consume_entry kernel/stacktrace.c:93 stack_trace_consume_entry kernel/stacktrace.c:86 Link: http://lkml.kernel.org/r/20200116111449.217744-1-dvyukov@gmail.com Signed-off-by: Dmitry Vyukov Reviewed-by: Andrey Konovalov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/Makefile | 1 + lib/Makefile | 1 + mm/Makefile | 1 + 3 files changed, 3 insertions(+) diff --git a/kernel/Makefile b/kernel/Makefile index f2cc0d118a0b..4cb4130ced32 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -27,6 +27,7 @@ KCOV_INSTRUMENT_softirq.o := n # and produce insane amounts of uninteresting coverage. KCOV_INSTRUMENT_module.o := n KCOV_INSTRUMENT_extable.o := n +KCOV_INSTRUMENT_stacktrace.o := n # Don't self-instrument. KCOV_INSTRUMENT_kcov.o := n KASAN_SANITIZE_kcov.o := n diff --git a/lib/Makefile b/lib/Makefile index 5fb02b93b1dc..23ca78d43d24 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -16,6 +16,7 @@ KCOV_INSTRUMENT_rbtree.o := n KCOV_INSTRUMENT_list_debug.o := n KCOV_INSTRUMENT_debugobjects.o := n KCOV_INSTRUMENT_dynamic_debug.o := n +KCOV_INSTRUMENT_fault-inject.o := n # Early boot use of cmdline, don't instrument it ifdef CONFIG_AMD_MEM_ENCRYPT diff --git a/mm/Makefile b/mm/Makefile index 1937cc251883..32f08e22e824 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -20,6 +20,7 @@ KCOV_INSTRUMENT_kmemleak.o := n KCOV_INSTRUMENT_memcontrol.o := n KCOV_INSTRUMENT_mmzone.o := n KCOV_INSTRUMENT_vmstat.o := n +KCOV_INSTRUMENT_failslab.o := n CFLAGS_init-mm.o += $(call cc-disable-warning, override-init) CFLAGS_init-mm.o += $(call cc-disable-warning, initializer-overrides)