| Message ID | 20240722223726.194658-1-andrey.konovalov@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kcov: don't instrument lib/find_bit.c | expand |
On Tue, 23 Jul 2024 at 00:37, <andrey.konovalov@linux.dev> wrote: > > From: Andrey Konovalov <andreyknvl@gmail.com> > > This file produces large amounts of flaky coverage not useful for the > KCOV's intended use case (guiding the fuzzing process). > > Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> > --- > > I noticed this while running one of the syzkaller's programs. > > In one run of the program, the number of KCOV entries amounts to ~300k, > with the top ones: > > 117285 /home/user/src/lib/find_bit.c:137 (discriminator 10) > 116752 /home/user/src/lib/find_bit.c:137 (discriminator 3) > 2455 /home/user/src/lib/vsprintf.c:2559 > 2033 /home/user/src/fs/kernfs/dir.c:317 > 1662 /home/user/src/fs/kernfs/kernfs-internal.h:72 > ... > > In another run (that triggers exactly the same behavior in the kernel), > the amount of entries drops to ~110k: > > 7141 /home/user/src/lib/find_bit.c:137 (discriminator 10) > 7110 /home/user/src/lib/find_bit.c:137 (discriminator 3) > 2455 /home/user/src/lib/vsprintf.c:2559 > 2033 /home/user/src/fs/kernfs/dir.c:317 > 1662 /home/user/src/fs/kernfs/kernfs-internal.h:72 > ... > > With this patch applied, the amount of KCOV entries for the same program > remains somewhat stable at ~100k. > --- > lib/Makefile | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/Makefile b/lib/Makefile > index 322bb127b4dc..0fde1c360f32 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -14,6 +14,7 @@ KCOV_INSTRUMENT_list_debug.o := n > KCOV_INSTRUMENT_debugobjects.o := n > KCOV_INSTRUMENT_dynamic_debug.o := n > KCOV_INSTRUMENT_fault-inject.o := n > +KCOV_INSTRUMENT_find_bit.o := n > > # string.o implements standard library functions like memset/memcpy etc. > # Use -ffreestanding to ensure that the compiler does not try to "optimize" > -- > 2.25.1 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20240722223726.194658-1-andrey.konovalov%40linux.dev.
diff --git a/lib/Makefile b/lib/Makefile index 322bb127b4dc..0fde1c360f32 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -14,6 +14,7 @@ KCOV_INSTRUMENT_list_debug.o := n KCOV_INSTRUMENT_debugobjects.o := n KCOV_INSTRUMENT_dynamic_debug.o := n KCOV_INSTRUMENT_fault-inject.o := n +KCOV_INSTRUMENT_find_bit.o := n # string.o implements standard library functions like memset/memcpy etc. # Use -ffreestanding to ensure that the compiler does not try to "optimize"