Re: [PATCH v7 23/23] selftests: Include tools Makefile.include

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Including `tools/scripts/Makefile.include` inside `tools/testing/selftests/lib.mk` breaks normal assignments to `EXTRA_CFLAGS` in selftest Makefiles, causing silent loss of compiler flags and test coverage.
--

commit 969534670ab7ca5eb2e61c1ef0a49417bd7e304d
Author: Leo Yan <leo.yan@arm.com>

selftests: Include tools Makefile.include

This commit includes tools/scripts/Makefile.include from selftests/lib.mk
to reuse LLVM cross-build validation and flags. It aims to improve Clang
cross builds by deriving cross-compile options directly from the GCC
cross toolchain.

> diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk
> index f02cc8a2e4ae3..e2e2d8aa57280 100644
> --- a/tools/testing/selftests/lib.mk
> +++ b/tools/testing/selftests/lib.mk
> @@ -1,11 +1,17 @@
[ ... ]
> +selfdir = $(realpath $(dir $(filter %/lib.mk,$(MAKEFILE_LIST))))
> +top_srcdir = $(selfdir)/../../..
> +
> +include $(top_srcdir)/tools/scripts/Makefile.include

[Severity: Medium]
Does including Makefile.include here break EXTRA_CFLAGS assignments in
individual selftest makefiles?

tools/scripts/Makefile.include modifies EXTRA_CFLAGS using the override
directive:

override EXTRA_CFLAGS += $(FLAG_ZERO_INIT)

According to GNU Make semantics, once a variable has been appended using
override, any subsequent normal assignments without override are ignored.

For example, tools/testing/selftests/x86/Makefile attempts to append
flags later:

EXTRA_CFLAGS += -DCAN_BUILD_32

Because of the earlier override, this normal assignment is silently dropped.
Consequently, tests like single_step_syscall.c evaluate #ifdef CAN_BUILD_32
as false in main(), silently skipping 32-bit specific test coverage.

Could this be resolved by either removing the override in Makefile.include
or updating selftest makefiles to also use override for EXTRA_CFLAGS?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260602-tools_build_fix_zero_init-v7-0-631baf679fe7@arm.com?part=23