overflow: disable failing tests for older clang versions
authorNick Desaulniers <ndesaulniers@google.com>
Thu, 6 Oct 2022 17:17:51 +0000 (10:17 -0700)
committerKees Cook <keescook@chromium.org>
Tue, 25 Oct 2022 21:57:42 +0000 (14:57 -0700)
commit0e5b9f25b27a7a92880f88f5dba3edf726ec5f61
treeb75a8d60cf459b3a8d55752161e4931f0ae86738
parent31970608a6d3796c3adbfbfd379fa3092de65c5d
overflow: disable failing tests for older clang versions

Building the overflow kunit tests with clang-11 fails with:

$ ./tools/testing/kunit/kunit.py run --arch=arm --make_options LLVM=1 \
overflow
...
ld.lld: error: undefined symbol: __mulodi4
...

Clang 11 and earlier generate unwanted libcalls for signed output,
unsigned input.

Disable these tests for now, but should these become used in the kernel
we might consider that as justification for dropping clang-11 support.
Keep the clang-11 build alive a little bit longer.

Avoid -Wunused-function warnings via __maybe_unused. To test W=1:

$ make LLVM=1 -j128 defconfig
$ ./scripts/config -e KUNIT -e KUNIT_ALL
$ make LLVM=1 -j128 olddefconfig lib/overflow_kunit.o W=1

Link: https://github.com/ClangBuiltLinux/linux/issues/1711
Link: https://github.com/llvm/llvm-project/commit/3203143f1356a4e4e3ada231156fc6da6e1a9f9d
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221006171751.3444575-1-ndesaulniers@google.com
lib/overflow_kunit.c