On 10/27/25 20:42, Kuniyuki Iwashima wrote:
While writing a selftest with kselftest_harness.h, I often want to check which paths are actually exercised.Let's support generating KCOV coverage data. We can specify the output directory via the KCOV_OUTPUT environment variable, and the number of instructions to collect via the KCOV_SLOTS environment variable. # KCOV_OUTPUT=$PWD/kcov KCOV_SLOTS=$((4096 * 2)) \ ./tools/testing/selftests/net/af_unix/scm_inq Both variables can also be specified as the make variable. # make -C tools/testing/selftests/ \ KCOV_OUTPUT=$PWD/kcov KCOV_SLOTS=$((4096 * 4)) \ kselftest_override_timeout=60 TARGETS=net/af_unix run_tests The coverage data can be simply decoded with addr2line: $ cat kcov/* | sort | uniq | addr2line -e vmlinux | grep unix net/unix/af_unix.c:1056 net/unix/af_unix.c:3138 net/unix/af_unix.c:3834 net/unix/af_unix.c:3838 net/unix/af_unix.c:311 (discriminator 2) ... or more nicely with a script embedded in vock [0]: $ cat kcov/* | sort | uniq > local.log $ python3 ~/kernel/tools/vock/report.py \ --kernel-src ./ --vmlinux ./vmlinux \ --mode local --local-log local.log --filter unix ... ------------------------------- Coverage Report -------------------------------- 📄 net/unix/af_unix.c (276 lines) ... 942 | static int unix_setsockopt(struct socket *sock, int level, int optname, 943 | sockptr_t optval, unsigned int optlen) 944 | { ... 961 | switch (optname) { 962 | case SO_INQ: 963 > if (sk->sk_type != SOCK_STREAM) 964 | return -EINVAL; 965 | 966 > if (val > 1 || val < 0) 967 | return -EINVAL; 968 | 969 > WRITE_ONCE(u->recvmsg_inq, val); 970 | break; Link: https://github.com/kzall0c/vock/blob/f3d97de9954f9df758c0ab287ca7e24e654288c7/report.py #[0] Signed-off-by: Kuniyuki Iwashima <[email protected]> --- v2: Support TEST() v1: https://lore.kernel.org/linux-kselftest/[email protected]/ --- Documentation/dev-tools/kselftest.rst | 41 ++++++ tools/testing/selftests/Makefile | 14 ++- tools/testing/selftests/kselftest_harness.h | 133 +++++++++++++++++++- 3 files changed, 178 insertions(+), 10 deletions(-)
I am okay with kcov support being added. You probably have to fix a few things. kernel test robot is still complaining on v2. thanks, -- Shuah
